Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit

Animals using sound for communication emit directional signals, focusing most acoustic energy in one direction. Echolocating bats are listening for soft echoes from insects. Therefore, a directional biosonar sound beam greatly increases detection probability in the forward direction and decreases off-axis echoes. However, high directionality has context-specific disadvantages: at close range the detection space will be vastly reduced, making a broad beam favorable. Hence, a flexible system would be very advantageous. We investigated whether bats can dynamically change directionality of their biosonar during aerial pursuit of insects. We trained five Myotis daubentonii and one Eptesicus serotinus to capture tethered mealworms and recorded their echolocation signals with a multimicrophone array. The results show that the bats broaden the echolocation beam drastically in the terminal phase of prey pursuit. M. daubentonii increased the half-amplitude angle from approximately 40° to approximately 90° horizontally and from approximately 45° to more than 90° vertically. The increase in beam width is achieved by lowering the frequency by roughly one octave from approximately 55 kHz to approximately 27.5 kHz. The E. serotinus showed beam broadening remarkably similar to that of M. daubentonii. Our results demonstrate dynamic control of beam width in both species. Hence, we propose directionality as an explanation for the frequency decrease observed in the buzz of aerial hawking vespertilionid bats. We predict that future studies will reveal dynamic control of beam width in a broad range of acoustically communicating animals.     

Factors increasing the caries risk of second primary molars in 5‐year‐old Dutch children

International Journal of Paediatric Dentistry 2010; 20: 151–157 Background. Caries is still a prevalent condition in 5‐year‐old children. At present, knowledge regarding some aetiological factors, like deciduous molar hypomineralization (DMH), is limited. Aim. To investigate aetiological factors both directly and indirectly associated with caries in second primary molars. Design. Of 974 children invited to participate in the study, 386 children were examined clinically with visual detection of caries. Only carious lesions determined to have reached the dentine were recorded. Information about tooth brushing frequency, education level of the mother, and country of birth of mother and child, was collected by means of a multiple‐choice questionnaire. Parents of 452 children filled in the questionnaire. Complete clinical and questionnaire data were available for 242 children. Statistical analysis of the effect of the independent variables was undertaken using the Pearson’s chi‐squared test. Results. Deciduous molar hypomineralization (P = 0.02) and the country of birth of the mother (P < 0.001) were positively associated with caries prevalence. Conclusions. Deciduous molar hypomineralization and the country of birth of the mother play a role in the prevalence of dental caries. These aetiological factors associated with childhood dental caries need to be investigated further in longitudinal clinical trials.     

One-day versus 3-day suprapubic catheterization after vaginal prolapse surgery: a prospective randomized trial

Introduction and hypothesis  

For prolonged catheterization after vaginal prolapse surgery with anterior colporrhaphy, the optimal duration to prevent overdistention of the bladder remains unknown. We designed this study to determine the optimal length of catheterization.     

Influence of chemical structure on hypersensitivity reactions induced by antiepileptic drugs: the role of the aromatic ring.

OBJECTIVE: Antiepileptic drugs (AEDs) can cause various 'idiosyncratic' hypersensitivity reactions, i.e. the mechanism by which AEDs induce hypersensitivity is unknown. The aim of this study was to assess whether the presence of an aromatic ring as a commonality in chemical structures of AEDs can explain symptoms of hypersensitivity. METHODS: Between January 1985 and January 2007, all adverse drug reactions (ADRs) reported to the Netherlands Pharmacovigilance Centre Lareb related to AEDs as suspected drugs were included in this study. ADRs were analysed using a case/non-case design. Cases were defined as those patients with ADRs involving symptoms of hypersensitivity. Non-cases were patients with all other ADR reports. Symptoms of hypersensitivity were classified according to the Gell and Coombs classification (type I-IV) and the organ involved (e.g. cutaneous, hepatic). AEDs were classified as aromatic anticonvulsant if their chemical structure contained at least one aromatic ring. All other AEDs were classified as non-aromatic. We assessed the strength of the association between aromatic AEDs versus non-aromatic AEDs and reported hypersensitivity reactions with logistic regression analysis and expressed these as reporting odds ratios (RORs). RESULTS: In total, 303 cases of hypersensitivity associated with the use of AEDs were reported. Aromatic AEDs were suspected in 64.4% of these reports versus 41.3% (574/1389) of the non-hypersensitivity reports. A significant ROR of 2.15 (95% CI 1.63, 2.82) was found for aromatic AEDs and all hypersensitivity reactions. Aromatic AEDs were significantly associated with immunoglobin E-mediated type I hypersensitivity reactions (ROR 2.15; 95% CI 1.23, 3.78) and T-cell-mediated type IV reactions (ROR 6.06; 95% CI 3.41, 10.75). Type II and III reactions did not show an association. Cutaneous symptoms represented 39.9% of the hypersensitivity-related ADRs. Aromatic AEDs were significantly associated with cutaneous hypersensitivity reactions (ROR 5.81; 95% CI 3.38, 9.99). CONCLUSION: This study confirms that the presence of an aromatic ring as a common feature in chemical structures of AEDs partly explains apparent 'idiosyncratic' hypersensitivity reactions. Symptoms of hypersensitivity were reported twice as frequently with aromatic AEDs than with non-aromatic AEDs. Strong associations for aromatic AEDs versus non-aromatic AEDs were found for T-cell-mediated (type IV) reactions, as well as for cutaneous reactions.     

Recombinant factor VIIa reduces bleeding in severely thrombocytopenic rabbits

Severe thrombocytopenia is a common complication to intensive chemotherapeutic regimens. For bleeding episodes associated with severe thrombocytopenia, the current standard treatment is platelet transfusion. However, due to several transfusion complications such as transfusion-transmitted diseases, platelet refractoriness and immunomodulation, as well as increasing problems with sufficient supply of platelet products, it is imperative to search for alternatives to platelet transfusion. To test the efficacy of recombinant activated human coagulation factor VII (rFVIIa, NovoSeven) in thrombocytopenia, a preclinical study was conducted in thrombocytopenic rabbits. Thrombocytopenia was induced by a combination of gamma-irradiation and the use of platelet antibodies, and the effect of rFVIIa on nail cuticle bleeding was determined. Administration of rFVIIa at 2 mg/kg significantly shortened the prolonged bleeding time in thrombocytopenic animals (rFVIIa vs. control, median 23 min 41 s vs. 60 min, p=0.016) as well as significantly reducing the blood loss (rFVIIa vs. control, median: 8.8 vs. 12.2 nmol hemoglobin/ml, p=0.016). This effect was also reflected by a significant reduction of the prothrombin time, activated partial thromboplastin time, as well as improvement in clotting parameters in an in vitro thromboelastography thrombocytopenia model. Histopathological evaluation of kidney biopsies for the presence of micro thrombi did not reveal evidence of prothrombotic effects of rFVIIa in this model. These data demonstrate the haemostatic efficacy of rFVIIa in a rabbit model of severe thrombocytopenia. Clinical trials will be needed to further explore the potential of NovoSeven as a haemostatic agent in thrombocytopenic patients.     

Salter innominate osteotomy for the treatment of developmental dysplasia of the hip in children: results of seventy-three consecutive osteotomies after twenty-six to thirty-five years of follow-up

BACKGROUND: Reorientation of the acetabulum may be necessary in the treatment of an unstable hip in children with developmental dysplasia of the hip. In 1961, Salter described the innominate osteotomy for stabilizing the reduced hip in the position of function by redirection of the acetabulum as one piece. In the present study, we describe our long-term results with this procedure. METHODS: We reviewed the cases of sixty-one patients who had seventy-three Salter innominate osteotomies. At the time of the operation, the mean age of the patients was 4.1 years (range, 1.3 to 8.8 years). Radiographs made preoperatively, postoperatively, and at the time of the most recent follow-up visit were evaluated. Clinical evaluation was performed with use of the Merle d'Aubigné and Postel system as well as the Harris hip score. RESULTS: The mean duration of follow-up was 30.9 years (range, 26.2 to 35.4 years). There were seven true revisions (one acetabuloplasty, one triple osteotomy, and five total hip arthroplasties). With true revision as the end point, the cumulative survival rate at 35.3 years was 0.90. Fifteen of the seventy-three hips were considered a failure, which was defined as a revision or a Harris hip score of <70 points and/or a Merle d'Aubigné and Postel score of <13 points. The long-term clinical outcome was significantly influenced by the grade of dislocation on the radiographs made at the first examination (p = 0.0388) and on those made immediately preoperatively (p < 0.0001), the postoperative summarized hip factor (the radiographic grade of dysplasia) (p = 0.0002), the preoperative (p = 0.0392) and postoperative (p = 0.0072) grades of avascular necrosis of the femoral head, and the technique of reduction (p < 0.0001). CONCLUSIONS: When an acetabulum can be most closely restored to a normal configuration without the development of avascular necrosis, good long-term results (lasting for more than thirty years) can be expected. When open reduction is necessary, it is preferable to perform it separately prior to the Salter innominate osteotomy. The grade of dislocation at the time of the first examination and immediately preoperatively, the grade of avascular necrosis of the femoral head, and the adequacy of surgical correction are important prognostic factors for the long-term clinical result.     

Circulating DNA: a new diagnostic gold mine?

The recent discovery that cell-free DNA can be shed into the bloodstream as a result of tumour cell death has generated great interest. Numerous studies have demonstrated tumour-specific alterations in DNA recovered from plasma or serum of patients with various malignancies, a finding that has potential for molecular diagnosis and prognosis. The implication is that tumour-derived nucleic acids of human or viral origin can be retrieved from blood by a minimally invasive procedure, and used as a surrogate tumour marker to monitor the course of the disease or aid in early diagnosis. The present review will describe the main areas of ongoing investigation, with particular emphasis on technical issues and available data of clinical relevance.     

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.