Effects of temperature on metabolic rate during metamorphosis in the alfalfa leafcutting bee

Spring conditions, especially in temperate regions, may fluctuate abruptly and drastically. Environmental variability can expose organisms to temperatures outside of their optimal thermal ranges. For ectotherms, sudden changes in temperature may cause short- and long-term physiological effects, including changes in respiration, morphology, and reproduction. Exposure to variable temperatures during active development, which is likely to occur for insects developing in spring, can cause detrimental effects. Using the alfalfa leafcutting bee, Megachile rotundata, we aimed to determine if oxygen consumption could be measured using a new system and to test the hypothesis that female and male M. rotundata have a thermal performance curve with a wide optimal range. Oxygen consumption of M. rotundata pupae was measured across a large range of temperatures (6-48°C) using an optical oxygen sensor in a closed respirometry system. Absolute and mass-specific metabolic rates were calculated and compared between bees that were extracted from their brood cells and those remaining in the brood cell to determine whether pupae could be accurately measured inside their brood cells. The metabolic response to temperature was non-linear, which is an assumption of a thermal performance curve; however, the predicted negative slope at higher temperatures was not observed. Despite sexual dimorphism in body mass, sex differences only occurred in mass-specific metabolic rates. Higher metabolic rates in males may be attributed to faster development times, which could explain why there were no differences in absolute metabolic rate measurements. Understanding the physiological and ecological effects of thermal environmental variability on M. rotundata will help to better predict their response to climate change.

Physiological responses to cryoprotectant treatment in an early larval stage of the malaria mosquito, Anopheles gambiae

The development of cryopreservation protocols for Anopheles gambiae could significantly improve research and control efforts. Cryopreservation of any An. gambiae life stage has yet to be successful. The unique properties of embryos have proven to be resistant to any practical cryoprotectant loading. Therefore, we have chosen to investigate early non-feeding first instar larvae as a potential life stage for cryopreservation. In order to determine an appropriate cryoprotective compound, larvae were treated with progressively better glass-forming cryoprotective mixtures. Toxicity evaluation in combination with calorimetry-based water content and supercooling point depression assessments were used to determine the cryoprotectants that could be used for cryostorage of viable larvae. Approximately 35-75% of the larvae were viable after reasonably high osmotic and biochemical challenge. This study provides ample evidence for an active osmoregulatory response in the Anopheles larvae to counter the permeation of cryoprotectants from the surrounding medium. The data show a strong correlation between the larval mortality and water content, indicating an osmoregulatory crisis in the larva due to certain cryoprotectants such as the higher concentrations of ethane diol (ED). The observations also indicate that the ability of the larvae to regulate permeation and water balance ceases at or within 20 min of cryoprotectant exposure, but this is strongly influenced by the treatment temperature. Among the compound cryoprotectants tested, 25% ED + 10% dimethyl sulfoxide (DMSO) and 40% ED + 0.5 M trehalose seem to present a compromise between viability, larval water content, supercooling point depression, and glass forming abilities.

Metabolomics of anoxia tolerance in Drosophila melanogaster: evidence against substrate limitation and for roles of protective metabolites and paralytic hypometabolism

Animals vary tremendously in their capacities to survive anoxia, and the mechanisms responsible are poorly understood. Adult Drosophila melanogaster are rapidly paralyzed and survive up to 12 h of anoxia, whereas larvae vigorously attempt escape but then die if anoxia exceeds 2 h. Here we use nuclear magnetic resonance methods to compare the metabolome of larvae and adult D. melanogaster under normoxic conditions and after various anoxic durations up to 1 h. Glucose increased during anoxia in both larvae and adults, so anoxic death by carbohydrate limitation is unlikely for either stage. Lactate and alanine were the primary anaerobic end products in both adults and larvae. During the first 30 min of anoxia, larvae accumulated anaerobic end products (predominately lactate) at a higher rate, suggesting that larvae may experience greater initial acid-base disruption during anoxic exposures. Adult Drosophila did not possess higher levels of putative protective metabolites; however, these increased during anoxia in adults and decreased in larvae. Metabolites that decreased during anoxia in larvae included mannitol, xylitol, glycerol, betaine, serine, and tyrosine, perhaps due to use as fuels, antioxidants, or binding to denatured proteins. Adults showed significant increases in glycine, taurine, and the polyols glycerol, mannitol, and xylitol, suggesting that adults upregulate protective metabolites to prevent damage. Our results suggest that lower initial metabolic demand due to paralytic hypometabolism and capacities to upregulate protective metabolites may assist the better anoxia tolerance of adult Drosophila.

Effects of anoxia on ATP, water, ion and pH balance in an insect (Locusta migratoria)

When exposed to anoxia, insects rapidly go into a hypometabolic coma from which they can recover when exposed to normoxia again. However, prolonged anoxic bouts eventually lead to death in most insects, although some species are surprisingly tolerant. Anoxia challenges ATP, ion, pH and water homeostasis, but it is not clear how fast and to what degree each of these parameters is disrupted during anoxia, nor how quickly they recover. Further, it has not been investigated which disruptions are the primary source of the tissue damage that ultimately causes death. Here, we show, in the migratory locust (Locusta migratoria), that prolonged anoxic exposures are associated with increased recovery time, decreased survival, rapidly disrupted ATP and pH homeostasis and a slower disruption of ion ([K⁺] and [Na⁺]) and water balance. Locusts could not fully recover after 4 h of anoxia at 30°C, and at this point hemolymph [K⁺] was elevated 5-fold and [Na⁺] was decreased 2-fold, muscle [ATP] was decreased to ≤3% of normoxic values, hemolymph pH had dropped 0.8 units from 7.3 to 6.5, and hemolymph water content was halved. These physiological changes are associated with marked tissue damage in vivo and we show that the isolated and combined effects of hyperkalemia, acidosis and anoxia can all cause muscle tissue damage in vitro to equally large degrees. When locusts were returned to normoxia after a moderate (2 h) exposure of anoxia, ATP recovered rapidly (15 min) and this was quickly followed by recovery of ion balance (30 min), while pH recovery took 2-24 h. Recovery of [K⁺] and [Na⁺] coincided with the animals exiting the comatose state, but recovery to an upright position took ∼90 min and was not related to any of the physiological parameters examined.

Paralytic hypo-energetic state facilitates anoxia tolerance despite ionic imbalance in adult Drosophila melanogaster

Oxygen limitation plays a key role in many pathologies; yet, we still lack a fundamental understanding of the mechanisms responsible for variation in anoxia tolerance. Most vertebrate studies suggest that anoxia tolerance involves the ability to maintain cellular ATP despite the loss of aerobic metabolism. However, insects such as adult Drosophila melanogaster are able to survive long periods of anoxia (LT₅₀: ∼8 h) in a hypo-energetic state characterized by low [ATP]. In this study, we tested for possible mechanisms that allow D. melanogaster adults to survive long periods of anoxia. Adults are paralyzed within 30 s, and after 2 h of anoxia, ATP was 3% of normal, extracellular potassium concentration ([K⁺]_o) increased threefold, pH dropped 1 unit, yet survival was 100%. With 0.5-6 h of anoxia, adults maintained low but constant ATP levels while [K⁺]_o and pH_o continued to change. When returned to normoxia, adults restored [K⁺]_o and activity. With longer durations of anoxia, ATP levels decreased and [K⁺]_o rose further, and both correlated tightly with decreased survival. This response contrasts with the anoxia-sensitive larval stage (LT₅₀: ∼1 h). During anoxia, larvae attempted escape for up to 30 min and after 2 h of anoxia, ATP was <1% of resting, [K⁺]_o increased by 50%, hemolymph pH fell by 1 unit, and survival was zero. The superior anoxia tolerance of adult D. melanogaster appears to be due to the capacity to maintain a paralytic hypometabolic state with low but non-zero ATP levels, and to be able to tolerate extreme extracellular ionic variability.

Larval starvation improves metabolic response to adult starvation in honey bees (Apis mellifera L.)

Environmental changes during development have long-term effects on adult phenotypes in diverse organisms. Some of the effects play important roles in helping organisms adapt to different environments, such as insect polymorphism. Others, especially those resulting from an adverse developmental environment, have a negative effect on adult health and fitness. However, recent studies have shown that those phenotypes influenced by early environmental adversity have adaptive value under certain (anticipatory) conditions that are similar to the developmental environment, though evidence is mostly from morphological and behavioral observations and it is still rare at physiological and molecular levels. In the companion study, we applied a short-term starvation treatment to fifth instar honey bee larvae and measured changes in adult morphology, starvation resistance, hormonal and metabolic physiology and gene expression. Our results suggest that honey bees can adaptively respond to the predicted nutritional stress. In the present study, we further hypothesized that developmental starvation specifically improves the metabolic response of adult bees to starvation instead of globally affecting metabolism under well-fed conditions. Here, we produced adult honey bees that had experienced a short-term larval starvation, then we starved them for 12 h and monitored metabolic rate, blood sugar concentrations and metabolic reserves. We found that the bees that experienced larval starvation were able to shift to other fuels faster and better maintain stable blood sugar levels during starvation. However, developmental nutritional stress did not change metabolic rates or blood sugar levels in adult bees under normal conditions. Overall, our study provides further evidence that early larval starvation specifically improves the metabolic responses to adult starvation in honey bees.

Inter-rater reliability of the APD, SFU and UTD grading systems in fetal sonography and MRI

INTRODUCTION

Antenatal hydronephrosis (ANH) is frequently detected on screening obstetric ultrasonography. Common ANH grading systems include the anterior-posterior diameter (APD) and the Society for Fetal Urology (SFU) grading system. Recent developments in the management of ANH include the use of fetal magnetic resonance imaging (MRI), and a new grading system - Urinary Tract Dilation (UTD). This study reviewed patients who underwent fetal MRI and ultrasound, and compared the grading systems across these imaging modalities.

MATERIALS AND METHODS

Patients who underwent paired fetal MRI and ultrasound studies between January 2012 and January 2014 were included. Two pediatric urologists and a pediatric radiologist reviewed the studies. Data collected included APD, SFU grade, and UTD grade. Fleiss' kappa statistic determined the inter-rater reliability (IRR) of the SFU and UTD grading within each imaging modality. Intra-class correlation assessed the consistency of the APD measurements.

RESULTS

Forty-seven patients and 88 renal units were evaluated. Median gestational age was 22 weeks. Kappa values of the SFU grading system indicated fair IRR for ultrasound imaging and moderate IRR for MRI imaging, while the UTD grading system reached moderate IRR for both. The IRR of the SFU grading system was improved with the use of MRI, while the UTD grading system was no different. The APD intraclass correlation coefficient improved significantly when measured by MRI. As the ultrasound SFU grade increased, the odds of the MRI SFU grade being scored higher increased by a factor of 3.7. There was no difference between ultrasound and MRI when using the UTD grading system.

DISCUSSION

This study was the first to assess the UTD system in a cohort of patients who underwent paired ultrasound and MRI studies. The results suggested that the UTD system might improve IRR, compared with the SFU system. The use of fetal MRI may improve the IRR of the SFU grading system. It also found that the proportion of SFU grades was affected by the imaging modality, raising the possibility that MRI 'overcalls' the SFU grade, compared with ultrasound. This difference was not observed using the UTD grading system. The most important limitation was the selection bias favoring complex pathology with severe ANH diagnosed at an early gestational age.

CONCLUSIONS

In this unique cohort, the UTD system improved IRR when compared to the SFU grading system. Fetal MRI improved the IRR of the SFU grading system, and improved the APD intraclass correlation. The SFU grading was likely to be higher when assessed by MRI vs ultrasound, but the UTD grade was not affected by the imaging modality.

Temperature and the Ventilatory Response to Hypoxia in Gromphadorhina portentosa (Blattodea: Blaberidae)

In general, insects respond to hypoxia by increasing ventilation frequency, as seen in most other animals. Higher body temperatures usually also increase ventilation rates, likely due to increases in metabolic rates. In ectothermic air-breathing vertebrates, body temperatures and hypoxia tend to interact significantly, with an increasing responsiveness of ventilation to hypoxia at higher temperatures. Here, we tested whether the same is true in insects, using the Madagascar hissing cockroach, Gromphadorhina portentosa (Schaum) (Blattodea: Blaberidae). We equilibrated individuals to a temperature (beginning at 20 °C), and animals were exposed to step-wise decreases in PO2 (21, 15, 10, and 5 kPa, in that order), and we measured ventilation frequencies from videotapes of abdominal pumping after 15 min of exposure to the test oxygen level. We then raised the temperature by 5 °C, and the protocol was repeated, with tests run at 20, 25, 30, and 35 °C. The 20 °C animals had high initial ventilation rates, possibly due to handling stress, so these animals were excluded from subsequent analyses. Across all temperatures, ventilation increased in hypoxia, but only significantly at 5 kPa PO2 Surprisingly, there was no significant interaction between temperature and oxygen, and no significant effect of temperature on ventilation frequency from 25 to 35 °C. Plausibly, the rise in metabolic rates at higher temperatures in insects is made possible by increasing other aspects of gas exchange, such as decreasing internal PO2, or increases in tidal volume, spiracular opening (duration or amount), or removal of fluid from the tracheoles.

The fungicide Pristine® inhibits mitochondrial function in vitro but not flight metabolic rates in honey bees

Honey bees and other pollinators are exposed to fungicides that act by inhibiting fungal mitochondria. Here we test whether a common fungicide (Pristine®) inhibits the function of mitochondria of honeybees, and whether consumption of ecologically-realistic concentrations can cause negative effects on the mitochondria of flight muscles, or the capability for flight, as judged by CO2 emission rates and thorax temperatures during flight. Direct exposure of mitochondria to Pristine® levels above 5 ppm strongly inhibited mitochondrial oxidation rates in vitro. However, bees that consumed pollen containing Pristine® at ecologically-realistic concentrations (≈ 1 ppm) had normal flight CO2 emission rates and thorax temperatures. Mitochondria isolated from the flight muscles of the Pristine®-consuming bees had higher state 3 oxygen consumption rates than control bees, suggesting that possibly Pristine®-consumption caused compensatory changes in mitochondria. It is likely that the lack of a strong functional effect of Pristine®-consumption on flight performance and the in vitro function of flight muscle mitochondria results from maintenance of Pristine® levels in the flight muscles at much lower levels than occur in the food, probably due to metabolism and detoxification. As Pristine® has been shown to negatively affect feeding rates and protein digestion of honey bees, it is plausible that Pristine® consumption negatively affects gut wall function (where mitochondria may be exposed to higher concentrations of Pristine®).

Developmental changes in hypoxic exposure and responses to anoxia in Drosophila melanogaster

Holometabolous insects undergo dramatic morphological and physiological changes during ontogeny. In particular, the larvae of many holometabolous insects are specialized to feed in soil, water or dung, inside plant structures, or inside other organisms as parasites where they may commonly experience hypoxia or anoxia. In contrast, holometabolous adults usually are winged and live with access to air. Here we show that larval Drosophila experience severe hypoxia in their normal laboratory environments; third instar larvae feed by tunneling into a medium without usable oxygen. Larvae move strongly in anoxia for many minutes, while adults (like most other adult insects) are quickly paralyzed. Adults survive anoxia nearly an order of magnitude longer than larvae (LT50: 8.3 vs. 1 h). Plausibly, the paralysis of adults is a programmed response to reduce ATP need and enhance survival. In support of that hypothesis, larvae produce lactate at 3x greater rates than adults in anoxia. However, when immobile in anoxia, larvae and adults were similarly able to decrease their metabolic rate in anoxia, to about 3% of normoxic conditions. These data suggest that Drosophila larvae and adults have been differentially selected for behavioral and metabolic responses to anoxia, with larvae exhibiting vigorous escape behavior likely enabling release from viscous anoxic media to predictably normoxic air, while the paralysis behavior of adults maximizes chances of survival of flooding events of unpredictable duration. Developmental remodeling of behavioral and metabolic strategies to hypoxia/anoxia is a previously unrecognized major attribute of holometabolism.

Dispersal of stable flies (Diptera: Muscidae) from larval development sites in a Nebraska landscape

Seven mark-recapture studies were conducted over 3 yr to assess dispersal of newly emerging adult stable flies, Stomoxys calcitrans L., from larval development sites in a mixed agricultural environment in northeastern Nebraska. Infested hay debris piles were marked by dusting their surfaces with fluorescent pigments, adults were captured with surrounding grids of Alsynite sticky traps, and specimens were dissected to determine feeding histories and reproductive age. Distances and directions of 3,889 marked specimens indicated males and females dispersed equally and in all directions. Midguts of males and females were equally likely to contain blood-meal remnants. Percentage with blood remnants and percentage of females with yolk increased with distance from mark origin, indicating survival and spread were positively associated with host finding success. A time-integrated diffusion model fit to results from the seven studies indicated 50% of stable fly adults had dispersed beyond 1.6 km of their natal site, but only 5% had dispersed beyond 5.1 km. These results indicate that stable fly adults on cattle in a given area are most likely to have originated from larval development sites within an ≈ 5 km radius of the subject cattle.

Effects of stable flies (Diptera: Muscidae) on weight gains of grazing yearling cattle

Differences in weight gains caused by stable flies, Stomoxys calcitrans (L.), on grazing yearling steer/calves averaged 0.2 kg per steer in a 3-yr study on canyon range pastures in West Central Nebraska, Stable fly numbers averaged 0.85 per front leg on treated calves and 3.64 per front leg on control calves. In 2 of the 3 yr after the grazing trials were completed, the calves were placed in a feedlot and fed a finishing ration. Compensatory gain did not occur in the feedlot after the stable fly stress was removed.

Comparative efficacy of several insecticides for control of cattle lice (Mallophaga: Trichodectidae and Anoplura: Haematopinidae)

Several insecticides were applied to cattle at various rates, mixtures, application methods and numbers of treatments and evaluated for control of cattle lice. The insecticides included permethrin at various rates as a pour-on with and without the synergist piperonyl butoxide (PBO), and also at various rates as a spray with and without PBO. Pirimiphos-methyl was evaluated as a pour-on at various rates and with one or two applications. Lambda cyhalothrin in microencapsulated formulation was compared to a non-microencapsulated formulation. Rabon(R) was applied as a pour-on at two rates and at one or two treatments for each rate. Dimilin(R) was applied as a pour-on at two rates and mixed with permethrin and applied at two rates. Five endectocides, Eprinex(R), Ivomec(R), Dectomax(R), Cydectin(R) and Phoenectin(R) were all applied at the same rate. The cattle utilized in this research were all infested with a mixture of lice species. The species included: Bovicola (Damalinia) bovis (L.), Haematopinus eurysternus (Nitzsch), Linognthus vituli (L.) and Solenoptes capillatus (Enderlein). Most of the cattle were infested with at least two species and some had three or all four species present. All of the treatments except permethrin 1.0%+5% PBO, at a rate of 3ml/45.4kgwt. provided acceptable lice control with one application. Data indicated that applying the insecticides in early January should provide enough control to render the need for a second treatment unnecessary.

Chiropractors and vaccination: A historical perspective

Although there is overwhelming evidence to show that vaccination is a highly effective method of controlling infectious diseases, a vocal element of the chiropractic profession maintains a strongly antivaccination bias. Reasons for this are examined. The basis seems to lie in early chiropractic philosophy, which, eschewing both the germ theory of infectious disease and vaccination, considered disease the result of spinal nerve dysfunction caused by misplaced (subluxated) vertebrae. Although rejected by medical science, this concept is still accepted by a minority of chiropractors. Although more progressive, evidence-based chiropractors have embraced the concept of vaccination, the rejection of it by conservative chiropractors continues to have a negative influence on both public acceptance of vaccination and acceptance of the chiropractic profession by orthodox medicine.

Jansen type of spondylometaphyseal dysplasia

Metaphyseal dysplasia, type Jansen (JMD), is a rare skeletal dysplasia with characteristic radiographic abnormalities. Of the various types of metaphyseal dysplasia, JMD shows the most severe alteration in metaphyseal architecture. All of the long tubular bones, including those of the hands and feet, show metaphyseal irregularity with a fragmented appearance and slight widening. The adjacent physes are abnormally widened, while the epiphyses tend to be slightly enlarged, rounded but otherwise normal. The spine in infancy and childhood usually appears normal. This report describes a young girl with metaphyseal changes typical of JMD except for the hands and feet, which appeared normal. She also showed very unusual abnormalities of the spine. This appears, therefore, to represent a unique osteochondrodysplasia for which we propose the term spondylometaphyseal dysplasia, type Jansen.

Hepatic pulmonary fusion in neonates

OBJECTIVE

This report discusses the relationship of supradiaphragmatic hepatic tissue that is fused to the lung (through a diaphragmatic defect) with pulmonary hypoplasia-a new constellation of findings.

CONCLUSION

Hepatic pulmonary fusion should be suspected in instances of apparent diaphragmatic hernia characterized by mediastinal shift towards the hypoplastic lung or when the mediastinum does not shift away from the mass.

Metaphyseal chondrodysplasia, type Jansen

The Jansen type of metaphyseal dysplasia is a rare disorder with significant clinical and radiographic variability. Two cases of classical Jansen disease and one with some distinctive features suggestive of the Jansen variant are reported.

Fibrogenesis imperfecta ossium: imaging correlation in three new patients

OBJECTIVE

Fibrogenesis imperfecta ossium is an extremely rare disorder that can easily be misdiagnosed. We retrospectively reviewed the clinical and imaging data of three confirmed cases of fibrogenesis imperfecta.

DESIGN AND PATIENTS

The patients consisted of two men and one woman, ranging in age from 40 to 53 years. Radiography was performed in all the patients. One patient had a 3-year follow-up of the thoracolumbar spine with conventional radiography and thoracolumbar magnetic resonance (MR) imaging. Open biopsy was performed in all cases, confirming the diagnosis of fibrogenesis imperfecta ossium.

RESULTS

All our cases demonstrated "fishnet" trabecular pattern by conventional radiographs, and a pelvis radiograph of one patient showed an equivocal sclerosis pattern. Multiple fractures were noted in two patients. A pseudoexostosis was present in the ilium in one patient. Thoracolumbar MR imaging demonstrated diffuse low signal intensity within the medullary space on both T1-weighed and T2-weighted images, except for a region of increased signal intensity in the L1 and L2 vertebral bodies on T2-weighed images due to edema from acute collapse.

CONCLUSIONS

Although uncommon, fibrogenesis imperfecta ossium should be considered in a previously healthy patient with a combination of progressive bone pain, unexplained fractures, a radiologic pattern of fishnet osteopenia and MR imaging of low signal intensity bone marrow on both T1-weighted and T2-weighted images.

Use of nonprescription medications by patients with congestive heart failure

OBJECTIVE

To define the utilization pattern of nonprescription therapies in patients with congestive heart failure (CHF) and to compare this pattern with that of an age- and gender-matched control group without any self-reported heart conditions.

DESIGN

Survey questionnaire completed by participants at home.

SETTING

Ambulatory CHF clinic in a tertiary care hospital.

SUBJECTS

Patients attending the clinic between July 1995 and May 1996 who agreed to participate. Control subjects were age- and gender-matched participants identified and approached by participating patients.

OUTCOME MEASURES

Nonprescription therapies used at least once weekly.

RESULTS

Completed questionnaires were received from 180 (75%) of the 239 patients who agreed to participate and from 133 controls. Mean age of responding patients was 69 years (63% men). Controls were younger, with a mean age of 64 years (63% men). The most commonly used nonprescription medication categories for both patients and controls, with no significant intergroup differences, were vitamins and minerals (59% patients, 50% controls), pain relievers (48% and 43%, respectively), herbal or health food products (38% and 38%), antacids (26% and 28%), and laxatives (24% and 21%). Significantly fewer patients than controls used cough and cold products (9% vs. 17%; p < 0.05), specifically oral decongestants (0.6% vs. 5%; p < 0.01), and more patients than controls used nutritional supplements (17% vs. 4%; p < 0.01).

CONCLUSIONS

Overall, use of nonprescription therapies by our CHF clinic patients is similar to that of an age- and gender-matched population without a self-reported heart condition. The differences in medication use observed between patients and controls included cough and cold products that might be harmful. This likely reflects appropriate caution with which CHF patients approach nonprescription therapies.

Malignancies in pediatric patients with ataxia telangiectasia

BACKGROUND

Patients with ataxia telangiectasia (AT), known to have an inherent increased susceptibility to the development of cancer, may present with malignancies that are unusual for the patient's age, are often difficult to diagnose clinically and radiographically and respond poorly to conventional therapy.

MATERIALS AND METHODS

We reviewed the clinical presentation and imaging studies of 12 AT patients who developed malignancies.

RESULTS

Eight of the twelve patients developed non-Hodgkin's lymphoma (CNS, thorax, bone), two developed Hodgkin's disease, and two were diagnosed with gastrointestinal mucinous adenocarcinoma.

CONCLUSION

The lymphomas were commonly extra nodal, and infiltrative rather than mass-like. The recognition of the tumors was often delayed due to confusion with the known infectious complications in AT patients.

Upper extremity and rib stress fractures in a child

Stress fractures in children are rare compared with the incidence in adults. This report describes an 11-year-old girl with stress fractures of the acromion, clavicle, and first rib on the left and contralateral fractures of the first and second ribs. It was eventually discovered that these fractures were caused by a nervous tic consisting of repetitive, vigorous shrugging and translation of the shoulders.

Chylothorax as a manifestation of child abuse

OBJECTIVE

Chylothorax presenting in a child without a well defined etiology may be a manifestation of child abuse. We recently observed a child with bilateral chylothoraces who demonstrated coexisting nonaccidental injuries. It is our intention to alert physicians to the association of chylothorax with nonaccidental trauma and review the prior medical literature.

DESIGN

Case report.

SETTING

Pediatric emergency department and intensive care unit.

PATIENT

An 18-month-old female child who presented with respiratory distress and failure to thrive.

INTERVENTIONS

Diagnostic and therapeutic thoracentesis. Skeletal survey and radionuclide bone scan. Nutritional support.

OUTCOME MEASURES

Pleural fluid is characterized as chylous if it contains significant numbers of lymphocytes and lipid. Unexplained fractures of the ribs and long bones in varying stages of healing are considered nonaccidental. Failure to thrive may be considered nonorganic when nutritional support alone results in significant weight gain.

RESULTS

Our patient presented with respiratory distress of one-week duration and failure to gain weight during the prior five months. The chest radiograph demonstrated bilateral pleural effusions, which were aspirated. The aspirate contained 1733 cells/mm3 (98% lymphocytes), which were lipid laden. The triglyceride concentration was 806 mg/dl. A skeletal survey demonstrated bilateral first rib, clavicle, and ulnar fractures. A radionuclide bone scan additionally revealed multiple vertebral body fractures. Nutritional support alone resulted in significant weight gain. The patient was reported to local authorities as having been abused.

CONCLUSION

Child abuse should be considered as an etiology for cryptogenic chylothorax. Further studies should be undertaken in this circumstance to search for coexisting injuries, which may indicate nonaccidental trauma.

Susceptibility of stable flies (Diptera:Muscidae) from southeastern Nebraska beef cattle feedlots to selected insecticides and comparison of 3 bioassay techniques

Insecticide susceptibility of field populations of stable flies, Stomoxys calcitrans (L.), was assayed using 3 exposure techniques: treated filter papers, treated glass petri dishes, and topical applications. Both topical applications and residual exposure to treated glass surfaces were suitable for testing susceptibility of stable flies to permethrin, stirofos, or methoxychlor. Residues on filter papers yielded inconsistent results with stirofos and methoxychlor. Significant concentration-mortality regression lines were generated with permethrin residues on filter papers, but approximately 1,000 times more insecticide was required to produce a toxic response when compared with permethrin residues on glass. Because of higher variability in response and the greater amount of insecticide required, residues on filter papers do not appear appropriate to test insecticide susceptibility in stable flies. Paired comparisons of field (F) and susceptible (S) stable flies resulted in field to susceptible ratios significantly > 1.0 only when the flies were treated topically, which suggests that topical application is more sensitive than residues on glass for the insecticides tested. Topical treatment with permethrin resulted in one FS(LD90) of 1.8-fold. Topical treatment with methoxychlor resulted in one FS(LD90) of 3.4-fold. However, the magnitude of these ratios is not larger than the significant differences observed within the susceptible laboratory colony from one generation to another. Intense exposure to insecticides is not known to have occurred in these field populations, indicating that the observed differences are the result of natural variation among stable fly populations and unrelated to prior selection with insecticides.

Calculating economic injury levels for stable flies (Diptera:Muscidae) on feeder heifers

A procedure for calculating the economic injury levels for stable flies, Stomoxys calcitrans (L.), on feeder heifers was developed from reduction of average daily weight gain-stable fly population level data in 8 independent replicated experiments over 17 yr. A negative exponential was fitted to the data using nonlinear regression. Regression coefficients were then used to derive a simple predictive equation for calculating the economic injury level in relation to cost of controlling stable flies in the feedlot, and the market value of heifers. Examples for calculating the economic injury level under practical feedlot situations are presented. Also included are recommendations for a simple random sampling design for stable flies in feedlots.

The effects of disposable daily wear contact lenses on goblet cell count

PURPOSE

The number of goblet cells on the inferior bulbar conjunctiva increases in response to daily wear contact lens use. We conducted a study to examine whether daily wear soft contact lenses worn on a 2-week disposable schedule would also induce the same goblet cell response.

METHODS

Twenty-eight subjects who had never worn contact lenses were fit with 38% water polymacon lenses. The lenses were worn on a daily wear basis and replaced every two weeks over a 6-month period. Goblet cell count was determined by impression cytology of the inferior bulbar conjunctiva.

RESULTS

No significant increase in goblet cell count was observed in the subjects during the 6 months period; the 3.23% baseline goblet cell count was never exceeded. In our previous study, after 6 months of conventional daily wear lens use, the goblet cell count increased from a baseline of 4.19% to 8.0%.

CONCLUSIONS

It appears that wearing daily wear soft contact lenses on a disposable basis may be less irritating to the ocular surface than wearing soft contact lenses on a conventional daily wear basis.

Duration of immunity in foxes vaccinated orally with ERA vaccine in a bait

Red foxes (Vulpes vulpes) vaccinated orally with the ERA strain of rabies vaccine in a bait were challenged after 83 mo. Ten of 11 foxes that had seroconverted following vaccination resisted challenge with a virulent rabies virus which produced clinical signs of rabies in 6 of 6 unvaccinated foxes. Five of 11 vaccinated animals retained titers of rabies virus neutralizing antibody throughout the period. Although 6 of 11 had no detectable antibody at the time of challenge, 5 of these 6 resisted challenge and had an anamnestic response, as indicated by elevated titers of antibody when measured at day 77 postchallenge. These results show that foxes can be immunized successfully with a single oral dose of ERA vaccine, probably with protection against a lethal rabies challenge, for at least 7 y.

Human adenovirus type 5 vectors expressing rabies glycoprotein

The prevalence of wildlife rabies throughout the world and the continued spread of this disease in North America highlights the need for oral vaccines which may be used safely and effectively to vaccinate a number of species that are reservoirs or vectors of rabies. We have previously shown that AdRG1, a replication competent recombinant human adenovirus type 5 (Ad5) expressing a rabies glycoprotein (RG), can induce immunity to rabies in rodent, canine, and skunk model systems. To improve the Ad5 vector system as a potential oral vaccine, we have constructed additional Ad5 recombinant vectors and compared RG expression in cell culture and immunogenicity in animals. Two new replication competent vectors are compared. AdRG1.3, which carries RG with accompanying SV40 poly A addition sequences within an E3 deletion, and AdRG4, which has RG in the E3 deletion but under the control of an exogenous Ad2 major late promoter, both express higher levels of RG in permissive cell culture than did AdRG1 and both elicit high levels of serum anti-rabies antibodies by parenteral or oral routes in animals. AdRG1.3 may be a more effective vaccine vector in species which are non-permissive for the replication of human Ad5.

Cause-specific noncardiac mortality in patients with congestive heart failure--a contemporary Canadian audit. Clinical Quality Improvement Network (CQIN) Investigators

BACKGROUND

Noncardiac mortality in congestive heart failure (CHF) is substantial.

OBJECTIVE

To define the specific causes of noncardiac mortality among hospitalized CHF patients.

DESIGN

Retrospective medical record audit.

SETTING

Three hospitals in British Columbia and Alberta, 1992-93.

PATIENTS

A total of 2216 consecutive patients admitted with CHF.

MAIN RESULTS

The overall mortality rate was 404 of 2216 (18%). Cause of death was cardiac in 290 of 404 (72%) patients, with an average age of 76 years. However, 114 of 404 (28%) deaths, in patients with an average age of 69 years, had noncardiac causes. Four causes accounted for almost 70%, of the noncardiac deaths: cancer (24%); pneumonia (16%); other pulmonary diseases, including embolism (15%); and cerebrovascular disease (11%). Renal disease (9%), gastrointestinal disorders (9%), non-pulmonic sepsis (7%), multiple system failure (5%) and trauma or surgical complications (4%) accounted for most of the remaining noncardiac deaths.

CONCLUSIONS

Noncardiac causes produce a substantial proportion of deaths among elderly and sick CHF patients. As the survival of patients with CHF improves, the relative risk of noncardiac mortality in this population will likely increase. However, since hospitalized CHF patients so closely reflect their general population counterparts in terms of cause-specific mortality risk, the search for an ideal therapy might be viewed as a quixotic search for the cure of death.

Synthesis of the four isomers of 4-aminopyrrolidine-2,4-dicarboxylate: identification of a potent, highly selective, and systemically-active agonist for metabotropic glutamate receptors negatively coupled to adenylate cyclase

The four isomers of 4-aminopyrrolidine-2,4-dicarboxylate (APDC) were prepared and evaluated for their effects at glutamate receptors in vitro. (2R,4R)-APDC (2a), an aza analog of the nonselective mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylate (1S,3R)-ACPD, 1), was found to possess relatively high affinity for metabotropic glutamate receptors (mGluRs) (ACPD-sensitive [3H]glutamate binding IC50 = 6.49 +/- 1.21 microM) with no effects on radioligand binding to NMDA, AMPA, or kainate receptors up to 100 microM. None of the other APDC isomers showed significant mGluR binding affinity, indicating that this interaction is highly stereospecific. Both 1 and 2a were effective in decreasing forskolin-stimulated cAMP formation in the adult rat cerebral cortex (EC50 = 8.17 +/- 2.21 microM for 1; EC50 = 14.51 +/- 5.54 microM for 2a); however, while 1 was also effective in stimulating basal tritiated inositol monophosphate production in the neonatal rat cerebral cortex (EC50 = 27.7 +/- 5.2 microM), 2a (up to 100 microM) was ineffective in stimulating phosphoinositide hydrolysis in this tissue preparation, further supporting our previous observations that 2a is a highly selective agonist for mGluRs negatively coupled to adenylate cyclase. Microelectrophoretic application of either 1 or 2a to intact rat spinal neurons produced an augmentation of AMPA-induced excitation (95 +/- 10% increase for 1, 52 +/- 6% increase for 2a). Intracerebral injection of 1 (400 nmol) produced characteristic limbic seizures in mice which are not mimicked by 2a (200-1600 nmol, ic). However, the limbic seizures induced by 1 were blocked by systemically administered 2a in a dose-dependent manner (EC50 = 271 mg/kg, ip). It is concluded that (2R,4R)-APDC (2a) is a highly selective, systemically-active agonist of mGluRs negatively coupled to adenylate cyclase and that selective activation of these receptors in vivo can result in anticonvulsant effects.

Comparison of core sampling and pupal traps for monitoring immature stable flies and house flies (Diptera: Muscidae) in beef feedlot pens

Core samples and cylindrical pupal traps were used to monitor immature stages of the stable fly, Stomoxys calcitrans (L.), and house fly, Musca domestica L., from 5 sample areas in beef feedlot pens: the feed apron-soil interface, the back fence, the side (pen dividing) fence, the mound, and the general lot. One feedlot was sampled during 1986, two feedlots were sampled in 1987, and three samples were taken at random from each sample area on each sample date. Core samples showed that both populations were highest from the feed apron sample area. Pupal traps tended to show the same result but differences between sample areas were not significant for immature stable flies. Both sampling methods generally indicated similar population trends of the 2 fly species over the season; correlation coefficients between the 2 sampling methods were generally significant but few correlations were strong and large divergences between population trends were present. Only approximately 69% of the total number of pupal traps placed were recovered; the loss of traps could have contributed to differences between the 2 sampling methods. Core sampling would be preferred if lower variance of samples is important; if collecting pupae of known age is important, then pupal traps may be useful if they are protected from trampling by cattle.

Scheduled sanitation to reduce stable fly (Diptera: Muscidae) populations in beef cattle feedlots

Sanitation has been long recommended as a means of reducing stable fly, Stomoxys calcitrans (L.), populations at cattle feedlots, but there is little published research to support this recommendation. In each of the 2 yr of this study, 4 feedlots received complete sanitation and 4 feedlots received no cleaning. The objective was to have the initial cleaning done before 1 June and then to reclean as needed every 2 wk thereafter. The feedlots that were cleaned had significantly fewer flies than the uncleaned feedlots, with 50.9% fewer stable flies during the 1st yr and 36.2% fewer flies in the 2nd yr. These reductions were realized even though initial cleaning was not done by 1 June in either year: bad weather delayed completion until 20 June the 1st yr and 29 June the 2nd yr. Sanitation at cattle feedlots significantly reduces stable fly populations and sanitation may have been more effective if initial cleaning was done by 1 June.

Should nasopharyngeal biopsy be mandatory in adult unilateral glue ear?

Unilateral secretory otitis media is a recognized presenting feature of nasopharyngeal neoplasia. In the two cases presented, biopsy from the nasopharynx revealed an unsuspected underlying adenocarcinoma. The need to biopsy the normal looking post-nasal space is highlighted.

Synthesis, antimicrobial activity and in vivo fluorine NMR of a hexafluorinated derivative of tilmicosin

A new fluorinated analog of tilmicosin was synthesized by the reductive amination of desmycosin with 3,5-bis(trifluoromethyl)piperidine. Despite an apparently small change in structure, the fluorinated analog had much less in vitro antimicrobial activity than tilmicosin and it failed to protect 3-day old chicks against a Pasteurella multocida challenge at 64 mg/kg sc. In a preliminary in vivo fluorine NMR experiment in a female Sprague-Dawley rat, a 19F NMR signal was detected in the liver one hour after ip administration of the fluorinated compound. Therefore, although this fluorinated derivative had less antimicrobial activity than tilmicosin, it may nevertheless provide a suitable model of tilmicosin for pharmacokinetic studies using in vivo fluorine NMR.

Atomic force microscope observations of otoconia in the newt

Calcitic and aragonitic otoconia from the Japanese red-bellied newt, Cynops pyrrhogaster, were examined using an atomic force microscope. The surface structure of both otoconial polymorphs consisted of arrays of elements approximately 50 nm in diameter. Elements were generally round and were separated by shallow depressions of no more than 20 nm. The elements are suggested to be single crystals of calcium carbonate. The relationship of these observations to theories of otoconial genesis is discussed.

Genetic homogeneity of cartilage-hair hypoplasia

Cartilage-hair hypoplasia (CHH) is an autosomal recessive metaphyseal chondrodysplasia characterized by short stature and hypoplasia of the hair. Associated pleiotropic features include deficient erythrogenesis, impaired T-cell mediated immunity, Hirschsprung's disease, and an increased risk of malignancies. CHH is most prevalent among the Old Order Amish in the United States and among the Finns, but sporadic families have been described among many other populations. We have previously mapped the gene for CHH to the short arm of chromosome 9 in Finnish and Amish families. The CHH locus resides close to D9S163 within an interval of 1.5 cM flanked by D9S165 and D9S50. In order to investigate the genetic homogeneity of CHH in various populations, we studied nine families with no genealogical connections to either Amish or Finns. No recombinants were detected between the CHH gene and any of the three closest marker loci studied, suggesting that CHH in these families results from mutation(s) at the same locus as in the Amish and Finnish families.

Overwintering of the stable fly (Diptera: Muscidae) in southeastern Nebraska

Adult stable flies, Stomoxys calcitrans (L.), were monitored during three winters at two, four, and 13 locations with Alsynite fiberglass traps and by examination of the interiors of buildings. No stable flies were found inside buildings during the winter. Adult stable flies were consistently caught on Alsynite traps at one location during two winters and at two other locations during one winter. Distribution and physiological age of these flies indicate that they emerged from pupae that had developed at or near the location where they were captured. Potential breeding sites were examined. A few third instars were found in silage in midwinter, but silage should not be considered a major source for overwintering stable flies.

The effects of daily wear contact lenses on goblet cell density

BACKGROUND

Some patients can wear contact lenses with a low tear breakup time while others with an identical tear breakup time cannot wear lenses. This suggests the current method of tear film assessment is inadequate at differentiating between these two types of patients. The study attempts to expand our knowledge of the tear film with special attention directed to a critical yet little studied component: mucin. Mucin is vital to maintenance of the tear film and functions as a tear film stabilizer. The condition of the precorneal tear film is a major determinant in the success of contact lens wear.

METHODS

Eighteen subjects free of ocular surface disease who had never worn contact lenses had the goblet cell density of their inferior bulbar conjunctiva determined by impression cytology. The subjects were then fit in a 38 percent water polymacon lens and their goblet cell density determined on a monthly basis for 6 months.

RESULTS

Nearly a 2-fold increase in goblet cell density was observed in 88 percent of the subjects over the 6-month period. The first statistically significant increase occurred 5 months after the initiation of lens wear when the goblet cell density rose from 4.19-7.84 percent.

CONCLUSIONS

We speculate the increase in goblet cells is an adaptive response of the ocular surface to a coated daily wear contact lens.

Inundative releases of pteromalid parasitoids (Hymenoptera: Pteromalidae) for the control of stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae) at confined cattle installations in west central Nebraska

Fly pupal parasitoids, primarily Muscidifurax raptor Girault and Sanders and Spalangia nigroaenea Curtis, purchased from commercial insectaries, failed to reduce numbers of stable fly, Stomoxys calcitrans (L.), significantly despite weekly releases of high numbers at one feedlot and one dairy during 1990 and a different feedlot and dairy in 1991. Parasitoid emergence from stable fly puparia were not significantly greater in the confinements where releases were made compared with confinements where no releases were made. The level of parasitism increased at all four confinements during and following parasitoid releases. Shipments of parasitoids contained neither the number requested or the species purity that had been anticipated. Both quantity and quality of parasitoids improved the second year of the research. The most numerous naturally occurring parasitoid species were also present at a new, relatively isolated feedlot by mid-July.

The clinical efficacy of Rev-Eyes in reversing the effects of pupillary dilation

BACKGROUND

Pupillary dilation to perform binocular indirect ophthalmoscopy has become a routine part of optometric practice. Many patients find the resulting photophobia and incapacity of near vision to be an inconvenience. Rev-Eyes (0.5% dapiprazole HCl) is a new alpha-antagonist reported to reverse the effects of pupillary dilation in approximately one hour. This study was designed to evaluate the usefulness of Rev-Eyes in a routine clinical setting.

METHODS

Seventy-nine subjects free of eye disease that ranged in age from 21 to 40 years received 0.5% proparacaine, 2.5% phenylephrine, and 1.0% tropicamide in each eye. Rev-Eyes was administered to 61 subjects. Eighteen control subjects received 5% NaCl. Effects on pupil diameter, accommodation, and distance and near visual acuity were measured. Conjunctival vasodilation, corneal stippling, patient comfort, and intraocular pressure (IOP) were also evaluated.

RESULTS

Our results confirm that a statistically significant reduction in pupil diameter is achieved 60 minutes after installation of Rev-Eyes. However, no significant improvement was obtained in any of the other functional aspects measured

CONCLUSIONS

Our data suggest limited utility for Rev-Eyes with a young population. The recovery rate of near visual acuity and amplitude of accommodation is identical with or without Rev-Eyes.

Average daily gains of Brahman-crossbred and English x exotic feeder heifers exposed to low, medium, and high levels of stable flies (Diptera: Muscidae)

Brahman-crossbred and English x Exotic feeder heifers were exposed to low (5 per leg), medium (12 per leg), and high (30 per leg) stable fly, Stomoxys calcitrans (L.), population levels to test relative tolerance of these cattle breeds to stable flies. The Brahman-crossbred heifers were tolerant to stable flies only when they were 12-13 mo old. At the same age, the English x Exotic heifers sustained reductions in average daily gain (ADG) at all three stable fly population levels of 0.22 kg/d (11.2%). At 14-15 mo of age, both breeds were affected only by the high stable fly level. The reduction in ADG was approximately 0.16 kg/d (10.6%) for both breeds. Stable fly numbers on the heifers varied with time of day. Both breeds appeared equally attractive to stable flies. With or without stable flies, the Brahman-crossbred heifers consistently gained less weight than the English x Exotic heifers by 0.24 kg/d (15%).

Does the location of the laryngectomy stoma influence its ultimate size?

The stoma following laryngectomy may be placed either within the incision or separately. To determine if this variation had a bearing on its ultimate size, measurements of the stoma size were carried out in 61 patients who underwent laryngectomy by one of these methods. It was found that the stoma was nearly twice the size in patients in whom the stoma had been sited within the main wound and that there was a minimal need for the use of a tube or stoma button post-operatively in these patients.

Renal derived epistaxis

A solitary metastasis to the nose from a renal cell carcinoma is extremely rare. One such case is presented and the argument for aggressive therapy to these lesions is reviewed.