Phylodynamic approaches to studying avian influenza virus.

Avian influenza viruses can cause severe disease in domestic and wild birds and are a pandemic threat. Phylodynamics is the study of how epidemiological, evolutionary, and immunological processes can interact to shape viral phylogenies. This review summarizes how phylodynamic methods have and could contribute to the study of avian influenza viruses. Specifically, we assess how phylodynamics can be used to examine viral spread within and between wild or domestic bird populations at various geographical scales, identify factors associated with virus dispersal, and determine the order and timing of virus lineage movement between geographic regions or poultry production systems. We discuss factors that can complicate the interpretation of phylodynamic results and identify how future methodological developments could contribute to improved control of the virus.

Establishment and cryptic transmission of Zika virus in Brazil and the Americas.

Transmission of Zika virus (ZIKV) in the Americas was first confirmed in May 2015 in northeast Brazil. Brazil has had the highest number of reported ZIKV cases worldwide (more than 200,000 by 24 December 2016) and the most cases associated with microcephaly and other birth defects (2,366 confirmed by 31 December 2016). Since the initial detection of ZIKV in Brazil, more than 45 countries in the Americas have reported local ZIKV transmission, with 24 of these reporting severe ZIKV-associated disease. However, the origin and epidemic history of ZIKV in Brazil and the Americas remain poorly understood, despite the value of this information for interpreting observed trends in reported microcephaly. Here we address this issue by generating 54 complete or partial ZIKV genomes, mostly from Brazil, and reporting data generated by a mobile genomics laboratory that travelled across northeast Brazil in 2016. One sequence represents the earliest confirmed ZIKV infection in Brazil. Analyses of viral genomes with ecological and epidemiological data yield an estimate that ZIKV was present in northeast Brazil by February 2014 and is likely to have disseminated from there, nationally and internationally, before the first detection of ZIKV in the Americas. Estimated dates for the international spread of ZIKV from Brazil indicate the duration of pre-detection cryptic transmission in recipient regions. The role of northeast Brazil in the establishment of ZIKV in the Americas is further supported by geographic analysis of ZIKV transmission potential and by estimates of the basic reproduction number of the virus.

H9N2 avian influenza virus dispersal along Bangladeshi poultry trading networks.

Avian influenza virus subtype H9N2 is endemic in Bangladesh's poultry population. The subtype affects poultry production and poses a potential zoonotic risk. Insufficient understanding of how the poultry trading network shapes the dissemination of avian influenza viruses has hindered the design of targeted interventions to reduce their spread. Here, we use phylodynamic analyses of haemagglutinin sequences to investigate the spatial spread and dispersal patterns of H9N2 viruses in Bangladesh's poultry population, focusing on its two largest cities (Dhaka and Chattogram) and their poultry production and distribution networks. Our analyses suggest that H9N2 subtype avian influenza virus lineage movement occurs relatively less frequently between Bangladesh's two largest cities than within each city. H9N2 viruses detected in single markets are often more closely related to viruses from other markets in the same city than to each other, consistent with close epidemiological connectivity between markets. Our analyses also suggest that H9N2 viruses may spread more frequently between chickens of the three most commonly sold types (sunali-a cross-bred of Fayoumi hen and Rhode Island Red cock, deshi-local indigenous, and exotic broiler) in Dhaka than in Chattogram. Overall, this study improves our understanding of how Bangladesh's poultry trading system impacts avian influenza virus spread and should contribute to the design of tailored surveillance that accommodates local heterogeneity in virus dispersal patterns.

Heme-heme orientation and electron transfer kinetic behavior of multisite oxidation-reduction enzymes.

Analysis of the polarized single-crystal absorption spectra of cytochrome cd1 of Pseudomonas aeruginosa shows that the heme c and heme d1 groups in each subunit are oriented perpendicularly to each other in both oxidized and reduced forms of the enzyme. These results, together with those of previous kinetic studies, indicate that a perpendicular heme-heme orientation may be an important factor in specifying kinetically slow steps in a sequential series of electron transfer reactions.

Smoking in the home and children's health.

OBJECTIVES: We estimate for young children the annual excess health service use, healthcare expenditures, and disability bed days for respiratory conditions associated with exposure to smoking in the home in the United States. METHODS: Health service use, healthcare expenditures and disability bed days data come from the 1999 and 2001 Medical Expenditure Panel Survey (MEPS). Reported smoking in the home comes from the linked National Health Interview Survey, from which the MEPS sample is drawn. Multivariate statistical analysis controls for potential confounding factors. The sample is 2759 children aged 0-4. RESULTS: Smoking in the home is associated with an increase in the probability of emergency department visits for respiratory conditions by five percentage points and the probability of inpatient use for these conditions by three percentage points. There is no relation between indoor smoking by adults and either ambulatory visits or prescription drug expenditures. Overall, indoor smoking is associated with $117 in additional healthcare expenditures for respiratory conditions for each exposed child aged 0-4. Indoor smoking is also associated with an eight percentage point increase in the probability of having a bed day because of respiratory illness for children aged 1-4. CONCLUSIONS: Despite the significant progress made in tobacco control, many children are still exposed to secondhand smoke in their home. Reducing exposure to smoking in the home would probably reduce healthcare expenditures for respiratory conditions and improve children's health.

Genomic and epidemiological monitoring of yellow fever virus transmission potential.

The yellow fever virus (YFV) epidemic in Brazil is the largest in decades. The recent discovery of YFV in Brazilian Aedes species mosquitos highlights a need to monitor the risk of reestablishment of urban YFV transmission in the Americas. We use a suite of epidemiological, spatial, and genomic approaches to characterize YFV transmission. We show that the age and sex distribution of human cases is characteristic of sylvatic transmission. Analysis of YFV cases combined with genomes generated locally reveals an early phase of sylvatic YFV transmission and spatial expansion toward previously YFV-free areas, followed by a rise in viral spillover to humans in late 2016. Our results establish a framework for monitoring YFV transmission in real time that will contribute to a global strategy to eliminate future YFV epidemics.

Failure of alpha-methyltyrosine to prevent hypertensive crisis in pheochromocytoma.

Sudden onset of a hypertensive crisis occurred shortly after induction of anesthesia in a patient with malignant pheochromocytoma, despite preoperative medical preparation with alpha-methyltyrosine (alpha-methyl-p-tyrosine) and propranolol hydrochloride. Other investigators have advocated alpha-methyltyrosine as the medical therapy of choice in the preoperative preparation of patients with pheochromocytoma. This case emphasizes the caution that should be exercised when using alpha-methyltyrosine preoperatively, without concurrent alpha-adrenergic blocking agents, to prevent intraoperative hypertensive crisis.

Acute interstitial nephritis associated with mezlocillin, nafcillin, and gentamicin treatment for Pseudomonas infection.

Two patients developed acute interstitial nephritis (AIN) following treatment with mezlocillin sodium. Diagnosis was made by renal biopsy. Gallium 67 citrate scanning was abnormal in both. All patients were receiving multiple-drug therapy, but AIN has either not been described with the other drugs, or the temporal relationship between the AIN and termination of other drug therapy makes a causative relationship unlikely. All were infected with Pseudomonas aeruginosa. A role for the infecting organism or drug synergism in contributing to the renal disease cannot be excluded.

Glucocorticoid excess during adolescence leads to a major persistent deficit in bone mass and an increase in central body fat.

Endogenous Cushing's syndrome (CS) in children causes growth retardation, decreased bone mass, and increased total body fat. No prospective controlled studies have been performed in children to determine the long-term sequelae of CS on peak bone mass and body composition. A 15-year-old girl with Cushing disease (CD), and her healthy identical co-twin, were followed for 6 years after the CD was cured. At the 6-year follow-up both twins had areal bone mineral density (BMD) and body composition determined by dual-energy X-ray absorptiometry (DXA) and three-dimensional quantitative computed tomography (3DQCT). Z scores for height, weight, and body mass index (BMI) were -2.3, -0.8 and 0.2, and 1.2, 0.2, and -0.6, in the twin with CD and her co-twin, respectively. In the twin with CD, areal BMD and bone mineral apparent density (BMAD) at different sites varied from 0.7 to 3 SD below her co-twin. Volumetric lumbar spine bone density Z score was -0.75 and 1.0, and total body, abdominal visceral, and subcutaneous fat (%) was 42, 10, and 41 versus 26, 4, and 17 in the twin with CD and her co-twin, respectively. The relationship between total body fat and L2-L4 BMAD was inverse in the twin with CD (p < 0.05), which by contrast in her co-twin was opposite and direct (p < 0.001). In the twin with CD, despite cure, there was a persistent deficit in bone mass and increase in total and visceral body fat. These observations suggest that hypercortisolism (exogenous or endogenous) during adolescence may have persistent adverse effects on bone and fat mass.

Six-year results of spironolactone and testolactone treatment of familial male-limited precocious puberty with addition of deslorelin after central puberty onset.

Short term treatment with spironolactone, testolactone, and, after the onset of central puberty, deslorelin can normalize the rate of growth and bone maturation in boys with familial male-limited precocious puberty. To test the hypothesis that this treatment can achieve long term normalization of the growth and development of these children, we examined the growth rate, bone maturation rate (change in bone age/change in chronological age), and predicted adult height of 10 boys who were treated with spironolactone (5.7 mg/kg x day) and testolactone (40 mg/kg x day) for at least 6 yr. Deslorelin (4 microg/kg x day) treatment was initiated 2.6 +/- 1.3 yr after beginning spironolactone and testolactone treatment. The growth rate normalized within 1 yr of starting treatment and remained normal during the next 5 yr of treatment (P < 0.001). The rate of bone maturation normalized during the second year of treatment and remained normal thereafter (P < 0.001). Predicted height increased from 160.7 +/- 14.7 centimeters at baseline to 173.6 +/- 10.1 centimeters after 6 yr of treatment (P < 0.05 during the fourth through the sixth year of treatment compared to baseline). We conclude that long term treatment with spironolactone, testolactone, and, after central puberty, deslorelin normalizes the growth rate and bone maturation and improves the predicted height in boys with familial male-limited precocious puberty. The ultimate effect of this approach on adult height will require further study.

Low growth hormone levels are related to increased body mass index and do not reflect impaired growth in luteinizing hormone-releasing hormone agonist-treated children with precocious puberty.

To test the hypothesis that GH deficiency might explain the low growth velocity of some LHRH agonist (LHRHa)-treated children with central precocious puberty, we measured stimulated (n = 81) and spontaneous (n = 32) GH levels during or after LHRHa treatment. GH stimulation tests in the children who were receiving LHRHa treatment were performed after 2 days of ethinyl estradiol administration. Thirty-one of 81 children (38%) who underwent GH stimulation tests had subnormal responses (less than or equal to 7 micrograms/L) to all tests administered (at least 2 stimuli), including 22 of 67 (33%) who had precocious puberty that was idiopathic or associated with hypothalamic hamartoma. Eleven of 32 children (34%) who underwent measurement of the mean nighttime spontaneous GH level had levels below the normal range for prepubertal children (less than 1.2 microgram/L). Despite the high incidence of subnormal GH levels, there appeared to be no relationship between the GH levels of these children and their growth characteristics. The height, growth velocity, bone maturation rate, predicted height, and insulin-like growth factor-I levels were not different between the children with low GH levels and the children with normal GH levels. Conversely, the GH levels were not different between the children with subnormal growth rates and the children with normal growth rates. Thus, variation in the growth rates of these LHRHa-treated children with central precocious puberty could not be explained by variation in the stimulated or spontaneous secretion of GH. In attempting to understand the high incidence of low GH levels in children with precocious puberty, we examined the relationship between GH level and body mass index (BMI). Both the stimulated (r = -0.33; P less than 0.002) and the spontaneous (r = -0.61; P less than 0.0002) GH levels were inversely related to BMI. Moreover, the children with precocious puberty as a group had significantly elevated BMI [1.2 +/- 0.1 (+/- SE) SD units] compared to normal children of the same age (P less than 0.0001). Thus, increased body mass may explain the high incidence of subnormal GH levels in these patients, and normative GH levels adjusted for body mass are needed before it can be concluded that the apparently subnormal GH levels in LHRHa-treated children with precocious puberty are in fact low.

Resumption of puberty after long term luteinizing hormone-releasing hormone agonist treatment of central precocious puberty.

To determine whether puberty resumes normally after long term LHRH agonist (LHRHa) treatment, we studied 16 children with central precocious puberty treated with LHRHa (D-Trp6,Pro9,NEt-LHRH) for 1-4 yr (mean, 3.3 yr). Treatment was discontinued at a mean age of 11.6 +/- 1.3 (+/- SD) yr. Plasma hormone levels, growth velocity, rate of bone maturation, and pubertal stage were assessed at the end of treatment and 3 and 12 months later. Basal plasma sex steroid and basal and LHRH-stimulated gonadotropin levels returned to near-pretreatment levels 3 months after discontinuation of therapy and were fully restored to pretreatment levels at 12 months. Growth velocity, which had been 7.8 cm/yr before treatment, was stable after discontinuation of treatment at approximately 2.6 cm/yr. The predicted height, which had increased during treatment (P less than 0.01), remained stable at approximately 5 cm above the pretreatment predicted height. The rate of bone age advancement (delta bone age/delta chronological age) increased gradually from 0.4 at the end of treatment to the normal value of 0.9 12 months posttreatment. Breast and pubic hair pubertal stages, which were stable throughout treatment and were 4.0 +/- 0.8 (+/- SD) and 3.6 +/- 1.0 at the end of treatment, increased to 4.9 +/- 0.2 and 4.5 +/- 1.0. This approximated the normal rate of 1 stage/yr. Menses occurred in 8 of 12 girls within 1 yr after treatment and in an additional 3 by 20 months after treatment. Six of the girls had menstruated before treatment, and all of these menstruated within 14 months after discontinuing therapy. We conclude that gonadotropin and sex steroid secretion and the clinical progression through puberty appear to resume normally after discontinuation of long term LHRHa treatment of central precocious puberty. Long term follow-up will be required, however, to determine whether the improvement in predicted height of these patients will be achieved, and whether adult reproductive function will be normal.

The effect of Cushing's disease on bone mineral density, body composition, growth, and puberty: a report of an identical adolescent twin pair.

As endogenous Cushing's syndrome (CS) in children occurs during a critical developmental period, when the majority of peak bone mass is acquired, we hypothesized that children with CS might be at an increased risk of osteoporosis. To determine the effects of CS on bone density, bone metabolism, and growth, we studied a 15-yr-old female identical twin pair, one of whom had CS (twin A), and the other of whom was healthy (twin B). Before therapy for CS, twin A showed a severe loss of bone mineral density [BMD; -3.2SD at the lumbar spine (LS)] compared to twin B (-0.1 SD), which in twin A was associated with low serum osteocalcin levels and urinary pyridinium cross-link excretion. Cure of CS in twin A led to a marked increase in these bone markers, suggesting a state of active bone remodeling. After 27 months of follow-up, even though twin A's BMD improved significantly, it still remained abnormal [-1.9 SD at LS compared with that of twin B (0 SD)], suggesting that twin A continued to be at increased long term risk of osteoporosis. In addition, as a consequence of CS, twin A's final height was 21 cm less than that of her identical twin. We recommend that all children with CS should have BMD monitored after treatment to determine the long term risk of osteoporosis.

Power deposition patterns in magnetically-induced hyperthermia: a two-dimensional low-frequency numerical analysis.

The electric fields and power deposition patterns generated in two-dimensional inhomogenous models exposed to the axially directed uniform magnetic fields of an infinitely long solenoid are calculated numerically. The fields are calculated using the method of moments (Galerkin procedure) with linear basis and weighting functions. This low-frequency analysis is useful for studying the power deposition patterns attributable to solenoidal inductive applicators operated at frequencies up to 13.56 MHz. For the models we have studied, the ratio of power per volume deposited into the tumor to power per volume deposited into the immediately surrounding tissue is largest for tumors in the lung, although the power per volume deposited into the outermost layer is still much larger than the power per volume deposited into the tumor; it may be possible, however, to cool this region adequately from the body surface. When the complex permittivity of the tumor model is similar to that of the region in which it is embedded, the currents in the torso and tumor circulate primarily around the center of the body, as has been previously calculated for concentric cylinders. When the complex permittivity of the tumor is much greater than the region in which it is embedded, the currents in the tumor circulate primarily around the center of the tumor.

Theoretical temperature profiles for concentric coil induction heating devices in a two-dimensional, axi-asymmetric, inhomogeneous patient model.

In this paper we report on theoretical calculations for the temperature distributions produced by an rf magnetic induction device that is placed concentrically about the long axis of the patient. A two-dimensional, axi-asymmetric, inhomogeneous patient model was used in conjunction with a numerical moment method for calculating the electric fields in the tissues of the model and a numerical finite element method for calculating the resulting temperature distributions. The electric fields and the absorbed power per unit volume of tissue were calculated for both a thorax and viscera model, each of which included a tumor volume. The absorbed power values were input into the bioheat transfer equation and the temperature distributions were calculated for a wide range of blood flow rates. Based on the steady-state and transient results, our computer simulations predict poor therapeutic temperature profiles for tumors embedded deeply in the thorax and viscera. This heating technique appears to produce significant therapeutic volumes in superficial tumors located not greater than 7 cm in depth. These theoretical calculations should aid the clinician in the evaluation of induction heating devices for their effectiveness in heating deep-seated and superficial tumors.

Enzyme replacement therapy for Gaucher disease: skeletal responses to macrophage-targeted glucocerebrosidase.

OBJECTIVES: Reversal of the hematologic and visceral abnormalities characteristic of Gaucher disease, the most common lipid storage disorder, with biweekly infusions of macrophage-targeted glucocerebrosidase (glucosylceramidase) is well documented. The extent to which the skeleton responds to enzyme replacement therapy has not been systematically investigated. METHODS: To assess the skeletal response to enzyme replacement therapy, we treated 12 patients with type 1 Gaucher disease, who had intact spleens, with macrophage-targeted glucocerebrosidase. The initial dose of enzyme was 60 U/kg body weight every 2 weeks for 24 months, followed by reduction in dosage to 30 and then 15 U/kg body weight every 2 weeks, each for 9 months. RESULTS: The lipid composition of bone marrow, determined by direct chemical analysis, began to improve after 6 months of treatment at a time when noninvasive imaging studies showed no significant changes. By 42 months, improvement in marrow composition was demonstrable on all noninvasive, quantitative imaging modalities (magnetic resonance score, quantitative xenon scintigraphy, and quantitative chemical shift imaging) used in this study. Quantitative chemical shift imaging, the most sensitive technique, demonstrated a dramatic normalization of the marrow fat content in all patients. Net increases in either cortical or trabecular bone mass, as assessed by combined cortical thickness measurements and dual-energy quantitative computed tomography, respectively, occurred in 10 patients. CONCLUSIONS: Prolonged treatment over 3 1/2 years with macrophage-targeted glucocerebrosidase produces objective reversal of disease in both the axial and appendicular skeleton in patients with Gaucher disease. Marked improvement occurs in marrow composition and bone mass in both children and adults.

Cranial CT findings in sclerosteosis.

Sclerosteosis or Van Buchem's disease is a rare genetic craniotubular hyperostosis that becomes evident in early childhood and is associated with progressive involvement of the skull. The pathologic changes in the cranium noted on CT are described in three cases. Although the disease is incurable, CT is useful to display the morbid anatomy of the cranium before palliative surgery.

Testing the HMO competitive strategy: an analysis of its impact on medical resources.

Competitive approaches to health care reform, including managed competition, are hypothesized to reduce health care expenditures and the resources devoted to medical care. Empirical evidence has been limited. The short- and long-run effects of an experiment closely resembling managed competition are analyzed. We examine effects on hospitals, technology diffusion, physicians, and health insurance premiums. The strategy reduces capital in hospitals, has minor effects on physicians and technology, and has only initial effects on average premiums.

Numerical optimization of 3-D SAR distributions in cylindrical models for electromagnetic hyperthermia.

Numerically optimized SAR (specific absorption rate) distributions in a source free 3-D multilayered concentric cylindrical (MCC) model are presented. The fields were expanded in the modes of the MCC. Cost functions which specify mathematically the relative weight assigned to differences between an SAR distribution and a desired SAR distribution were defined. The coefficients of the modes, which minimize the cost function, were obtained using gradient search optimization methods. The optimized SAR distributions shown were computed using three different cost functions and two different radial locations for the center of the region where the desired SAR is largest. A five-layered model, including the outer water layer for cooling and improved matching with the source, was used. The frequency was 70 MHz. The current and charge distributions computed on a perfectly conducting cylindrical surface just outside the model are also shown. The surface current and charge distributions depend strongly on the relative importance of the cost for acute heat and systemic heat. A technique is developed for generating a new set of basis functions for reducing the number of unknowns to be optimized. We suggest that the approach shown could be useful in designing hyperthermia applicators.

Use of a microcomputer to store information on radiology cases.

A microcomputer program for storage of qualitative patient data has been applied to CT and special procedures case data. Different vocabularies have been established and utilised for these two case categories. Experience over two years involving more than 10,000 cases is discussed. Utility for statistical, research, and patient care purposes is demonstrated.