The Acute Toxicity of Selected Alkylphenols to Young and AdultDaphnia magna

Differences in sensitivity toward toxicants between young and adult individuals in a population are assumed to be primarily associated with their difference in body size. This assumption plays a key role in the modeling of effects of variable concentrations of toxicants on nonhomogeneous populations. The hazard-based no-effect-concentrations (NECs), killing rates, and elimination rates, estimated from the survival data of a series of acute toxicity tests with young and adults ofDaphnia magnaand six alkylphenols, were used to evaluate this assumption. The results lead to the conclusion that young and adultD. magnawere equally sensitive in terms of NEC and killing rate and that the observed differences in elimination rates could be explained on the basis of a difference in body size. Furthermore, it was found that elimination rates estimated on the basis of the survival data were consistently smaller than those expected on the basis of a QSAR forDaphnia pulex, a comparable species. This discrepancy was likely due to a decreased uptake and elimination during a period of immobilization prior to death. Since it is unknown to what extent immobilized individuals are able to recover from short-term exposures, the observed deviation clearly identifies a complicating factor in the modeling of effects of variable concentrations of toxicants.     

A new technique for preparing precision-cut slices from small intestine and colon for drug biotransformation studies

INTRODUCTION: A new technique was developed to prepare precision-cut slices from small intestine and colon with the object of studying the biotransformation of drugs in these organs. METHODS: Rat intestinal slices were prepared in two different ways. In the first method, slices were punched out of the small intestine. In the second method, precision-cut slices were made from agarose-filled and -embedded intestines, using the Krumdieck tissue slicer. This method was also applied to colon tissue. Viability of the slices was determined by analysis of intracellular ATP and RNA levels and morphology. Drug metabolizing activity was studied using lidocaine, testosterone, and 7-ethoxycoumarin (7-EC) as phase I substrates, and 7-hydroxycoumarin (7-HC) as a phase II substrate. RESULTS: Precision-cut slices made from agarose-filled and -embedded intestine better preserved ATP levels than tissue that was punched out of the intestinal wall. After 24 h of incubation, morphology in precision cut-slices showed was quite well preserved while punched out tissue was almost completely autolytic after incubation. In addition, total RNA amount and quality was much better maintained in precision-cut slices, when compared to punched out tissue. Both intestinal slices and punched-out tissue showed high, and comparable, phase I and phase II biotransformation activities. DISCUSSION: It is concluded that preparing precision-cut 0.25 mm slices out of agarose-filled and -embedded intestine provides an improvement, compared with punched-out tissue, and that both intestinal and colon slices are useful preparations for in vitro biotransformation studies.     

Knowing the diagnosis and counselling the relatives of a person with dementia: the perspective of home nurses and home care workers in Belgium

Home nurses and home care workers share the care for a person with dementia with family caregivers, and are confronted with their needs for medical and service-related information, for advice on how to cope with the behaviour changes, and for emotional support. The first objective of the present study was to describe some of the conditions for effective counselling, such as the perception that knowing the diagnosis has positive consequences for the formal caregivers. A second objective was to describe the formal caregivers' counselling practice, and ascertain its relationship with the psychological variables of attitudes, self-efficacy and subjective norm. A postal questionnaire was sent to 287 home nurses and 1259 home care workers in a defined region of Belgium; the questionnaire was returned by 169 home nurses (58.9% response) and 665 home care workers (52.8% response). The Theory of Planned Behaviour was the organising framework which underpinned the development of the instruments. Only the 168 home nurses and 601 home care workers reporting experience with caregiving to people with dementia were included in the analysis. Formal caregivers indicated that knowing the diagnosis was important, but it could facilitate or hinder caregiving. They were able to describe behavioural characteristics which are indicative of dementia, but only in a limited way, and their strategies to uncover the diagnosis were also limited. Formal caregivers reported that they supported family members emotionally, advised about communication with the person with dementia and informed family caregivers about services. However, providing family caregivers with information about dementia lagged behind these forms of support. In general, nurses scored higher than home care workers. Multiple linear regression analysis was used to investigate the relationships between self-reported practice and the concepts of the model. In both professions, attitudes and self-efficacy were found to be strong independent predictors, and the implications for practice are discussed.     

High-throughput purification of viral RNA based on novel aqueous chemistry for nucleic acid isolation

BACKGROUND: Extraction protocols using magnetic solid phases offer a high potential for automation. However, commercially available magnetic-bead-based assays either lack the sensitivity required for viral diagnostics or are disproportionately expensive. METHODS: We developed an aqueous chemistry for extraction of viral nucleic acids from plasma samples by use of common magnetic silica beads. Nucleic acids were bound to the beads at acidic conditions in the presence of a kosmotropic salt and were eluted at a slightly alkaline pH. The method was implemented on a standard pipetting workstation for fully automated extraction of up to 48 samples of 240 muL plasma in 1 batch. RESULTS: The detection limit of the method was comparable to the spin-column-based QIAamp Viral RNA Mini Kit, which relies on chaotropic salts and binding to a silica membrane, as the comparison method. The 95% detection limit was 23.1 IU per PCR for HIV-1 and 10.7 IU per PCR for hepatitis C virus (HCV). Suitability for clinical routine testing was confirmed in a total of 178 HIV-1- or HCV-positive plasma samples. The method linearity (R(2)) was >0.99 for the viruses evaluated. CONCLUSIONS: Use of reagents without organic solvents allows simple and cost-effective automation of this method on common pipetting robots with low risk of contamination. Performance characteristics of the novel extraction method make it suitable for use in diagnosis of infectious diseases and viral load determinations.     

Criteria for early extubation after intracardiac surgery in adults

Of 142 adult patients undergoing open-heart surgery, 123 were extubated either in the operating room or within 3 hours after admission to the recovery room, to avoid the discomfort and risks of prolonged mechanical ventilation. The remaining 19 patients, who had impaired cardiac function, were mechanically ventilated for 1 to 7 days postoperatively. The most important criteria for cardiopulmonary malfunction indicating the need for continued mechnical ventilation were a low mixed venous O2 saturation (SVO2) of less than 60% and a high left atrial pressure (greater than 20 torr). Of the 123 patients, 118, had an uneventful postoperative recovery and 5 needed reintubation, 2 because of low SVO2 and 3 because of complications unrelated to respiratory management. Most adult patients can spontaneously breathe adequately immediately after or within 3 hours of completed open-heart surgery, but a thorough physiologic and clinical evaluation should precede extubation, to identify those who need prolonged mechanical ventilation in the postoperative phase. Criteria for selection of patients for early extubation are presented.     

IgM and IgG responses during chronic relapsing experimental allergic encephalomyelitis (r-EAE)

During chronic relapsing experimental allergic encephalomyelitis (r-EAE) in guinea pigs, serum IgM and IgG concentrations increased markedly early in disease. Serum IgM and IgG increased similarly in control animals immunized with Freund's incomplete adjuvant (FIA) and Mycobacterium tuberculosis (MT). In the chronic phase of r-EAE but not in control animals, elevated IgM was also found in central nervous system (CNS) extracts, suggesting intrathecal IgM synthesis. IgG antibodies against myelin and myelin basic protein (MBP) were regularly detected in r-EAE sera from day 21 post inoculation (p.i.), reaching maximum levels in the early chronic phase. IgG antibodies against galactocerebroside (GC) and galactose appeared in some r-EAE sera. Oligoclonal IgG bands were demonstrated in all r-EAE guinea pig sera 21-26 days p.i. The bands in serum decreased in number and strength in the chronic phase. They could be traced to antibodies against MT in 4 of 10 animals, but not to antibodies against myelin, MBP, GC or galactose. Oligoclonal IgG bands were also regularly visualized in r-EAE CNS 124 days p.i., suggesting persistent intrathecal IgG synthesis. They varied in number and migration between different regions of individual CNS. Oligoclonal CNS IgG was related to antibodies against MT in only one of 7 animals, and in no case to antibodies against myelin.     

Appearance of an interhemispheric cyst associated with agenesis of the corpus callosum

We describe a fetus with agenesis of the corpus callosum (ACC) and Dandy-Walker malformation that developed a frontal paramidline cyst late in gestation. The interval appearance of the cyst occurred in concert with increasing size of the lateral ventricles, which supports the hypothesis that cysts associated with ACC can develop with increasing intraventricular pressure. Recognition of the potential for a changing appearance of neurologic abnormalities is important to providing appropriate patient counseling.