First Hour Of Observation Research Articles

Ectoparasitism of the Flightless Drosophila melanogaster and D. hydei by the Mite Blattisocius mali (Acari: Blattisociidae).

Predatory mites dispersing by means of insects are often ectoparasites and may use various tactics to get onto the host, counteract its defenses, and diminish its survival. Blattisocius mali is a promising biological control agent which has been reported as transported by several drosophilid species. Our goal was to determine the type of relationship between this mite and fruit flies. We used flightless females of Drosophila melanogaster and D. hydei, which were commercially raised as live pet food. The predatory females mostly attacked the tarsi of the flies and then preferentially moved to the cervix or close to coxa III, where they eventually drilled their chelicerae and started feeding. Although both fly species used similar defensive tactics, more B. mali females did not attack D. hydei or did so with a delay, and a higher percentage of mites fell off the D. hydei tarsi during the first hour of observation. After 24 h, we noted the increased mortality of flies exposed to the presence of mites. Our study indicates the ectoparasitic relationship of B. mali with drosophilids. However, further research is needed to confirm the transport of this mite on wild D. hydei and D. melanogaster, both in the laboratory and under natural conditions.

A Comparison of Sloth Bear (Melursus ursinus) Diurnal Activity Between Winter and Summer Seasons in Captivity

Studies on captive animals provide information in terms of their welfare, health, management and exposition of natural behavior. A comparative study on diurnal activity of a captive male Sloth bear (Melursus ursinus) between winter and summer was carried out from November 2016 to May 2017 at Sajjangarh Biological Park, Udaipur (Rajasthan), India. The daily activity pattern of Sloth bear exhibited two peaks; the first initial peak was between first hour of observation i.e. 1000–1100 h, while second lower peak was between 0400 and 0500 h. Mid-day hours were reduced activity period. Most of activities showed similar daily routine in both seasons except basking, drinking and bathing (P < 0.05) and was seen possibly related to thermoregulation of animal in summer. Animal was found more active during winter (41.85%) then summer (38.07%), while overall majority of time was spend in resting (29.1%) and walking (22.6%). Resting was accounted highest in summer while walking was highest in winter season. No stereotypic behaviour was observed during the study.

A LOFAR observation of ionospheric scintillation from two simultaneous travelling ionospheric disturbances

This paper presents the results from one of the first observations of ionospheric scintillation taken using the Low-Frequency Array (LOFAR). The observation was of the strong natural radio source Cassiopeia A, taken overnight on 18–19 August 2013, and exhibited moderately strong scattering effects in dynamic spectra of intensity received across an observing bandwidth of 10–80 MHz. Delay-Doppler spectra (the 2-D FFT of the dynamic spectrum) from the first hour of observation showed two discrete parabolic arcs, one with a steep curvature and the other shallow, which can be used to provide estimates of the distance to, and velocity of, the scattering plasma. A cross-correlation analysis of data received by the dense array of stations in the LOFAR “core” reveals two different velocities in the scintillation pattern: a primary velocity of ~20–40 ms−1 with a north-west to south-east direction, associated with the steep parabolic arc and a scattering altitude in the F-region or higher, and a secondary velocity of ~110 ms−1 with a north-east to south-west direction, associated with the shallow arc and a scattering altitude in the D-region. Geomagnetic activity was low in the mid-latitudes at the time, but a weak sub-storm at high latitudes reached its peak at the start of the observation. An analysis of Global Navigation Satellite Systems (GNSS) and ionosonde data from the time reveals a larger-scale travelling ionospheric disturbance (TID), possibly the result of the high-latitude activity, travelling in the north-west to south-east direction, and, simultaneously, a smaller-scale TID travelling in a north-east to south-west direction, which could be associated with atmospheric gravity wave activity. The LOFAR observation shows scattering from both TIDs, at different altitudes and propagating in different directions. To the best of our knowledge this is the first time that such a phenomenon has been reported.

The Neuroprotective Effects of Histamine H3 Receptor Antagonist E177 on Pilocarpine-Induced Status Epilepticus in Rats.

Epilepsy is a multifaceted neurological disorder which severely affects neuronal function. Some patients may experience status epilepticus (SE), a life-threatening state of ongoing seizure activity linked to cognitive dysfunction, necessitating an immediate intervention. The potential of histamine H3 receptors in several neuropsychiatric diseases including epilepsy is well recognized. In the current study, we aimed to explore the effect of H3R antagonist E177 on prevention and termination of pilocarpine (PLC)-induced SE in rats as well as evaluating the effects of E177 on the levels of oxidative stress in hippocampus tissues. The results showed that the survival rate of animals pretreated with E177 (5 and 10 mg/kg, intraperitoneal (i.p.)) was significantly increased during the first hour of observation, and animals were protected from SE incidence and showed a prolonged average of latency to the first seizure when compared with animals pretreated with PLC (400 mg/kg, i.p.). Moreover, the protective effect of E177 (10 mg/kg) on SE was partially reversed when rats were co- administered with H3R agonist R-(α)-methylhistamine (RAM) and with the H2R antagonist zolantidine (ZOL), but not with the H1R antagonist pyrilamine (PYR). Furthermore, pretreatment with E177 (5 and 10 mg/kg) significantly decreased the abnormal levels of malondialdehyde (MDA), and increased levels of glutathione (GSH) in the hippocampal tissues of the treated rats. However, E177 failed to modulate the levels of catalase (CAT), superoxide dismutase (SOD), or acetylcholine esterase activity (AChE). Our findings suggest that the newly developed H3R antagonist E177 provides neuroprotection in a preclinical PLC-induced SE in rats, highlighting the histaminergic system as a potential therapeutic target for the therapeutic management of SE.

Productivity of spring grain crops depending on the method of basic treatment of the soil in the grain-cultivated crop rotation

Three-year scientific observations showed that in the arid conditions of the Saratov Trans-Volga region on dark chestnut soils in a grain-cultivated crop rotation before sowing spring wheat and barley, the highest soil density was after the minimum cultivation - 1.25 g/cm3. Plowing to a depth of 23–25 cm contributed to a decrease in the density of addition in the arable layer compared to subsurface cultivation by 9%, and compared to the minimal one – by 13%. Minimal treatment with a disc harrow BDM 7 Ch 3 to a depth of 10–12 cm reduced the permeability of dark chestnut soil by 38% in the first hour of observation and by 51% after the fourth hour compared to plowing. Before sowing spring early-ripening crops, the maximum moisture accumulation in the soil in a layer of 50–100 and 0–100 cm was after deep non-dump cultivation (13.9 and 15.7%), which was 1.5 and 0.5% more than the control values. During the tillering phase of spring wheat and barley, the maximum moisture content of the upper soil layer was noted in the control and after combined treatment (15.7–15.8%). The combined main processing of dark chestnut soils of the Saratov Trans-Volga region provided an increase in the yield of spring early crops by 0.8–3.0%. Minimization of soil cultivation reduced the productivity of barley and spring wheat by 23.3–28.2%, subsurface cultivation by 8.3–9.4% compared with the control. The coefficient of variation in the yield of spring wheat and barley by the main processing methods in 2017 was average and amounted to 11.3–15.2%, in 2018 it was insignificant - 6.3–6.9%, and in 2019 it was significant - 23, 5–40.9%.

Male guppies differ in daily frequency but not diel pattern of display under daily light changes

Sexually signalling animals must trade off the benefits of attracting mates with the consequences of attracting predators. For male guppies, predation risk depends on their behaviour, colouration, environmental conditions and changing intensity of predation throughout the day. Theoretically, this drives diel patterns of display behaviour in native Trinidadian populations, where males display more under low-light conditions when their most dangerous predator is less active. Here, we observed Australian guppies in a laboratory setting to investigate their diel display pattern, and if this pattern is controlled by ambient light intensity. We also quantified individual variation in both the daily frequency and diel pattern of displays, and if such variation relates to body size, colouration and a non-sexual behaviour. Under a typical daily light regime, male guppies displayed mostly in the first hour of observation. Extending the duration of dawn-like lighting, however, resulted in an extended period of high display, demonstrating that light intensity per se is an important cue for this behaviour. These findings mirror those obtained for Trinidadian populations, suggesting that male courtship timing is likely shaped by broad, potentially generalizable features of guppy ecology. The effect of acclimation to captive conditions on male behaviour is also discussed. Whereas the temporal pattern of display appeared consistent, individuals varied in their daily display frequency, and this was correlated with variation in colour phenotype and a measure of non-sexual risk acceptance behaviour. Such relationships pose promising avenues for integrating behavioural and sensory ecology with contemporary work on behavioural syndromes and animal personality. To limit the costs of their conspicuous colour patterns, male guppies should alter their behaviour to avoid predation. However, our understanding of how different individuals deal with this problem is lacking. Following individuals in the laboratory, we demonstrated individual variation in the daily frequency of male displays, and this was correlated with variation in colour phenotypes and non-sexual behaviour. However, all male guppies displayed more in the early hours of the day and extending the period of low lighting also extended this period of elevated display. These findings replicate and expand experiments on native populations, suggesting that male courtship timing is likely shaped by broad, potentially generalizable features of guppy ecology.

Prospective Evaluation of Safe Observation Period after Asymptomatic Penetrating Thoracic Injury: 1 Hour is Enough.

Introduction:The observation period was recently challenged by some studies; and it has been suggested that a 1-hour observation period may be sufficient to allow safe discharge in asymptomatic patients with penetrating thoracic injury (PTI) and normal initial Chest X-Ray (CXR).Objective:The current study was performed to investigate if in asymptomatic and hemodynamically stable patients with PTIs who has an initial normal evaluation, 1-hour observation interval is safe to detect clinically significant injuries and is it possible to discharge these patients safely after a negative Extended – Focused Assessment with Sonography in Trauma (E-FAST) at hour1 instead of hour 3.Method:This cross-sectional study was performed on asymptomatic patients with penetrating thoracic injury, referred to emergency department (ED) and normal initial CXR and the Extended Focused Assessment with Sonography in Trauma (E-FAST). The second E-FAST was done 1 hour after the first one and the third repeat E-FAST and control CXR then performed 3 hours post-injury. 24 hours follow up by phone call was done for each patient after discharge.Results:Finally, 117 patients with the average ages of 25.9 ± 7.8 years were enrolled of whom 92.5% were male. Eight patients developed PTX or HTX during first hour of observation that were diagnosed by E-FAST or CT scan requested by the in-charge physician. One hundred-nine patient completed E-FAST and radiograph studies at times zero, 1 h, and 3 h. One patient had a normal initial evaluation but demonstrated a PTX on the 3-h managed without intervention. The rate of delayed abnormality after an initially normal study was 7.7 % (9/117). No discharged patients returned to our ED with delayed manifestations of either PTX or HTX.Conclusion:The results of our study have shown that asymptomatic patients with PTI with negative initial evaluation and no deterioration at intervals, about 1 hour may be sufficient for detection of clinically significant pathology, considered for safe and early discharge.

Use of a standardized asthma severity score to determine emergency department disposition for paediatric asthma: A cohort study.

We recently introduced a clinical practice pathway for the management of asthma that uses the Pediatric Respiratory Assessment Measure (PRAM) to guide emergency department (ED) treatment and disposition. The pathway recommends discharge for patients who achieve improvement to PRAM <4 at 1 hour after the last bronchodilator. We evaluated practice variation and patient outcomes associated with PRAM-directed disposition recommendations. We conducted a retrospective cohort study of children aged 2 to 17 years treated for moderate asthma (PRAM score 4-7) using our asthma clinical pathway. We measured 1) the proportion of children discharged per pathway criteria who returned to our ED within 24 hours and 2) the proportion of children observed beyond the pathway discharge criteria who deteriorated (PRAM ≥4). We analyzed 385 patient records from September 2013 to February 2015. Among 145 (37.7%) patients discharged per pathway criteria, 4 (4/145; 2.8%) returned within 24 hours. The remaining 240 (62.2%) were observed beyond the pathway discharge criteria; 76/240 (31.7%) had a subsequent deterioration (PRAM score ≥ 4) and 25/240 (10.4%) were hospitalized. Of those who deteriorated, 46/76 (60.5%) worsened within the first additional hour of observation. We observed significant deviation from our PRAM-directed pathway discharge criteria and that a significant proportion of observed patients experienced clinical deterioration beyond the first hour of observation. We recommend observing children with moderate asthma for 2 or 3 hours from last bronchodilator therapy if PRAM < 4 is maintained, to capture the majority (97.7% or 99.7%) of patients who require further intervention and hospitalization.

Ketosis Level as a Factor Determining Addictive Behavior of Alcoholized Rats

A group of 20 rats was subjected to long-lasting alcoholization (90-day-long forced consumption of 10% aqueous ethanol solution, ES). Every day at 17.00, the ES volume consumed by the animals per day was measured, and the level of ketone bodies in the urine was estimated in points using a semiquantitative quick ketone test. Then, rats were divided into two equivalent groups, experimental and control ones (n = 10 in each group). During the subsequent three-day-long main stage of the experiment, animals of the experimental group were preliminarily (at 17.00 of the preceding day) subjected to peroral administration of 1.0 ml of solution of unithiol, i.e., an agent neutralizing ketone bodies. Within three days of the mentioned period, the level of ketonuria was estimated within a 9.00–17.00 observation period with one-hour-long intervals. This time, free access of rats to water or ES was provided. We found that rats of the experimental group consumed more than one-third of the daily ES norm within the first hour of observation; i.e., within the interval where the level of ketonuria was minimum (0.17 points, on average). After this, the amount of the consumed ES decreased, while the level of ketonuria increased significantly in a parallel manner. In control rats throughout the observation period, hourly consumption of ES and the level of ketonuria demonstrated no significant dynamics. We hypothesize that there is a causal relationship between the ketosis level and the behavioral reaction of alcohol consumption (the lower the ketosis, the higher the consumption). Under conditions of alcoholization resulting in the development of hypoglycemia, ketone bodies begin to be used in the brain as an energy substrate, and the brain becomes dependent on the level of ketonemia to a significant extent. These level is a rather important factor determining alcohol addiction; direct factors initiating a situational drive for alcohol consumption are hypoketonemia episodes.

Observation period for asymptomatic penetrating chest trauma: 1 or 3 h?

Current recommendations for evaluation and safe discharge of penetrating chest trauma patients regarding pneumothorax (PTX) include a Chest X Ray (CXR) at the Emergency Department (ED) upon arrival and second CXR after 3h if the first one is negative. To compare CXRs taken at the first and third hours of ED arrival and evaluate a 1h period of observation instead of 3h for safe discharge of patients with penetrating chest trauma. In this cross-sectional study, all asymptomatic patients with penetrating chest trauma referred to a level 1 trauma center with negative initial Postero-Anterior (PA) CXRs (hour 0) were enrolled. Those with intoxication, tube thoracostomy, chest computed tomography, evidence of abdominal penetration, an overall elapsed timed of more than 1h for admission to the ED, and refusal to take part in the study were excluded. Patients underwent subsequent PA CXRs at hours 1 and 3. A phone call follow up after 24h was organized for each patient. A total of 68 patients were enrolled. There was 100% concordance among CXRs performed at hours 1 and 3 in the study population. None of the patients showed clinical deterioration or PTX in CXR at hour 1 if remained asymptomatic during the first hour of observation. Asymptomatic patients with penetrating chest trauma, negative initial PA CXR, no signs of intoxication, and no deterioration during the first hour of observation may be considered for discharge. Further evidence is required to make recommendations based on these findings.

Prehospital Atrial Fibrillation: Clinical and Economic Aspects

Objective: to retrospectively study the results of emergency medical care for patients with uncomplicated attacks of atrial fibrillation and to provide a clinical and economic assessment of their prehospital management tactics. Material and methods. A comparative retrospective study was conducted to examine the results of emergency medical care rendered to 1200 patients with uncomplicated atrial fibrillation attacks lasting as long as 24 hours. Ambulance call and outpatient cards and inpatient case reports were used. A clinical and economic assessment of the prehospital management tactics for the patients was made. Results. The prehospital therapy of atrial fibrillation was found to be ineffective in the first hour of observation. In more than 90% of cases, an atrial fibrillation attack was eliminated by the end of the first 24 hours regardless of which antiarrhythmic agent had been used. Conclusion. The proposed prehos-pital management tactics for patients with uncomplicated atrial fibrillation attacks lasting as long as 24 hours make it possible to decrease the length of stay of a called ambulance team and to enhance its efficiency, without reducing the clinical effect of performed antiarrhythmic therapy. Key words: atrial fibrillation, emergency medical care, prehospi-tal stage, clinical and economic analysis.

Anticonvulsant effect of phytol in a pilocarpine model in mice

The present study investigated the effects of phytol in pilocarpine-induced seizures. The latency for development of convulsions and mortality rate was recorded in this model using mice. The results revealed that phytol (25, 50 and 75mg/kg, i.p.) increased latency to first seizure and decreased percentage of these seizures. Moreover, phytol also protected the animals against status epilepticus induced by pilocarpine, and decreased the mortality rate. Mice treated with pilocarpine (n=24) presented 100% of mortality during the first hour of observation. In turn, phytol-pretreated animals within 30min before the administration of pilocarpine (400mg/kg) remained alive during the first hour of observation. On the other hand, 6–8h after administration of pilocarpine it was observed that 10 (41.66%), 8 (33.33%) and 4 (16.66%) animals died (respectively). Thus, the pretreatment with phytol was able to block mortality rate during the first hour in acute phase of seizures, and significantly reduced this rate in a dose-dependent manner (p<0.05), suggesting an anticonvulsant effect. In addition, none of the phytol effects was blocked by pre-treatment with flumazenil, an antagonist of benzodiazepine receptors. In conclusion, phytol exhibits anticonvulsant activity by modulating of neurotransmitter systems, but further investigations are in progress to confirm this pharmacological property.

Peculiarities of the emergency care rendering for the patients with atrial fibrillation at a pre-admission stage: clinic-economic aspects

Comparative retrospective study of emergency care rendering results for 1200 patients with uncomplicated fibrillation attacks was carried out and their management tactics clinic-economic assessment at a pre-admission stage was done. It has been found that therapy for atrial fibrillation is unproductive in the first hour of observation at a pre-admission stage. Atrial fibrillation attack was eliminated to the end of the first day regardless of used antiarrhythmic preparation in more than 90% of the cases. Proposed management tactics for patients with uncomplicated atrial fibrillation attacks until 24 hours of duration at a pre-admission stage allows by cost lowering and clinical effect of conducting antiarrhythmic therapy maintenance to shorten an emergency team stay time and increase its operative turnover.

A mini-survey of ultracool dwarfs at 4.9 GHz

A selection of ultracool dwarfs are known to be radio active, with both gyrosynchrotron emission and the electron cyclotron maser instability being given as likely emission mechanisms. To explore whether ultracool dwarfs previously undetected at 8.5 GHz may be detectable at a lower frequency. We select a sample of fast rotating ultracool dwarfs with no detectable radio activity at 8.5 GHz, observing each of them at 4.9 GHz. From the 8 dwarfs in our sample, we detect emission from 2MASS J07464256+2000321, with a mean flux level of 286 $\pm$ 24 $\mu Jy$. The light-curve of 2MASS J07464256+2000321, is dominated towards the end of the observation by a very bright, $\approx $100 % left circularly polarized burst during which the flux reached 2.4 mJy. The burst was preceded by a raise in the level of activity, with the average flux being $\approx$ 160 $\mu Jy$ in the first hour of observation rising to $\approx$ 400 $\mu Jy$ in the 40 minutes before the burst. During both periods, there is significant variability. The detection of 100% circular polarization in the emission at 4.9 GHz points towards the electron cyclotron maser as the emission mechanism. However, the observations at 4.9 GHz and 8.5 GHz were not simultaneous, thus the actual fraction of dwarfs capable of producing radio emission, as well as the fraction of those that show periodic pulsations is still unclear, as indeed are the relative roles played by the electron cyclotron maser instability versus gyrosynchrotron emission, therefore we cannot assert if the previous non-detection at 8.5 GHz was due to a cut-off in emission between 4.9 and 8.4 GHz, or due to long term variability.

Not So Mural Thrombus

A 64-year-old man with type 2 diabetes mellitus was admitted to our emergency department for a 12-hour history of waxing and waning chest pain. During the first hour of observation, he complained about a new episode of chest pain accompanied by ST elevation in leads V2 and V3. The patient underwent emergency coronary angiography that showed 80% stenosis of the proximal left anterior descending artery with subocclusive thrombotic lesion …

Different effects of chronic exposure to ELF magnetic field on spontaneous and amphetamine-induced locomotor and stereotypic activities in rats

The effects of chronic (7 days) exposure to an extremely low frequency magnetic field (ELF-MF, 50 Hz, 0.5 mT) on spontaneous and amphetamine-induced (1.5 mg/kg, i.p.) locomotor and stereotypic activities in adult rats were examined by open field test for 2 h on exposure days 1, 3, and 7. After 1 day of exposure to ELF-MF, the spontaneous locomotor activity was increased clearly at the first hour of observation and significantly at the second one as compared to the corresponding values in other series with ELF-MF and sham-exposed animals. After 7 days of exposure to ELF-MF, an amphetamine enhancing effect on the locomotor activity was significantly reduced at the second hour of observation as compared to that in 1-day- and sham-exposed rats treated with amphetamine. In contrast to the locomotor activity, the amphetamine-induced stereotypic behaviour in 7-day pre-exposed rats was significantly reduced at the first hour versus sham-exposed rats. While at the second hour of observation this effect was significant as compared to 1- and 3-day exposed animals (but not sham-exposed rats). Our results indicate that an extremely low frequency magnetic field is able to affect differently two types of behaviour, which are dependent on both the time course of exposure and the imbalance in the brain mediatory systems.

Evaluation of meiotic spindles in thawed oocytes after vitrification using polarized light microscopy

To investigate the efficacy of the PolScope on imaging the spindle morphology in oocytes at the metaphase II stage before vitrification and after thawing. In vitro study. University infertility clinic and academic research laboratory. Oocytes at the metaphase II stage that were obtained from superovulating mice were vitrified and then thawed. Morphological features of the spindle in oocytes were evaluated by both the PolScope and immunofluorescent staining. Using the PolScope, the morphological features of the spindle of intact thawed oocytes were undetected by 3 hours of thawing in only 25% of cases. Most of the spindle images were recognized during the first hour of observation. Additionally, the statistical analysis of agreement of spindle morphology by both the PolScope and fluorescent staining showed a weighted Kappa value of 0.70, indicating good agreement. Oocytes with good spindle morphology verified by the PolScope before vitrification had a higher survival rate of intact oocytes after thawing compared with those with poor or undetected spindle images. The morphological features of the spindle in oocytes evaluated by the PolScope before freezing and after thawing are significantly correlated with those assessed by immunofluorescent staining after fixation. With the assistance of the PolScope, thawed oocytes with good spindle morphology can be verified and selected for further manipulation without fixation and staining.

Larval predation by Chrysomya albiceps on Cochliomyia macellaria, Chrysomya megacephala and Chrysomya putoria

Abstract Chrysomya albiceps, the larvae of which are facultative predators of larvae of other dipteran species, has been introduced to the Americas over recent years along with other Old World species of blowflies, including Chrysomya megacephala, Chrysomya putoria and Chrysomya rufifacies. An apparent correlate of this biological invasion has been a sudden decline in the population numbers of Cochliomyia macellaria, a native species of the Americas. In this study, we investigated predation rates on third instar larvae of C. macellaria, C. putoria and C. megacephala by third instar larvae of C. albiceps in no‐choice, two‐choice and three‐choice situations. Most attacks by C. albiceps larvae occurred within the first hour of observation and the highest predation rate occurred on C. macellaria larvae, suggesting that C. albiceps was more dangerous to C. macellaria than to C. megacephala and C. putoria under these experimental conditions. The rates of larvae killed as a result of the predation, as well as its implications to population dynamics of introduced and native species are discussed.

Epidemic meningococcemia and purpura fulminans with induced protein C deficiency.

Patients with epidemic infections caused by Neisseria meningitidis serogroup C were studied to assess the relationship of abnormal coagulation parameters to prognosis. Patients were categorized into stages within the first hour of observation according to severity of illness. During the epidemic years 1986 through 1991, 113 patients with bacteriologically proven N. meningitidis infection were observed, 15 of whom died. Purpura fulminans was seen in 28 patients, of whom 14 (50%) died. Among the 14 surviving patients who had purpura fulminans, 10 suffered gangrene with deforming autoamputation secondary to the dermal microvascular thrombosis and hemorrhagic necrosis. Evaluation of the induced diffuse intravascular coagulation in 59 patients included studies of the naturally occurring anticoagulants, focusing on protein C and protein S. The magnitude of the declining levels of protein C, the degree of thrombocytopenia, and the presence of fibrin split products are directly related to the clinical severity of the illness (P = .0053). Thus, in individuals with severe disease expression, the risk of purpura fulminans with death or deformity was significantly increased when the platelet count was < 50,000 cells/mm3 (P = .0001) and protein C levels were low (P = .0158). The immaturity of the protein C system in children who are < 4 years of age may contribute to the rapid and more frequent pathogenesis of purpura fulminans. Therapy directed at replacement of the naturally occurring anticoagulants, such as protein C, may ultimately improve the prognosis for individuals with purpura fulminans.

In vitro characteristics of spontaneous airway tone in the guinea-pig.

Spontaneous airway tone has been demonstrated in the guinea-pig and man in vitro but little data on the magnitude and time-course of this phenomenon is available. Moreover, the literature on possible mediators is conflicting. In the present in vitro study, spontaneous airway tone (measured as spontaneous active tension) was examined in frontally-opened guinea-pig airway rings (n = 4-8). The examination related to magnitude, time-course and segmental differences as well as the role of eicosanoids, acetylcholine and adrenergic mechanisms. Spontaneous active tension of considerable magnitude (approximately 40% of maximum active tension) and stability was recorded during the second hour of the experiments. An initial small segmental difference between the trachea and the main bronchus gradually decreased during the first hour of observation. Cyclooxygenase inhibition by indomethacin completely abolished the spontaneous active tension. The leukotriene antagonist FPL 55712 reduced the active tension, whereas the leukotriene antagonist L-648,051 did not significantly affect it. Muscarinic blockade and adrenergic depletion had no effect. We conclude that the spontaneous active tension is of such a large magnitude and stability that it may play an important role in maintaining normal airway tone and that there are no pronounced segmental differences. The complete inhibition by indomethacin and the lack of effect by L-648,051 indicate that the spontaneous airway tone is primarily maintained by prostanoids and suggest that leukotriene D4 is of minor importance. The effect of FPL 55712 was probably due to inhibition of phosphodiesterase.