Green Foxtail (Setaria viridis), A Naturally Infected Grass Host of Iris yellow spot virus in Utah

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) is a serious virus pathogen in onion bulb and seed crops in the United States and several parts of the world (1). The virus is exclusively transmitted by onion thrips (Thrips tabaci). Besides onion and other susceptible crops such as garlic, leek, chives, and several ornamentals, weeds could be serving as potential reservoir sources of virus inoculum. There are reports of several weeds found naturally infected with IYSV (1,2,4). However, there is no report of IYSV infection of a grass species. Leaves of green foxtail (Setaria viridis (L.) Beauv.) were collected from two naturally occurring plants approximately 30 m apart in a weed trial conducted in commercial onions grown in Box Elder County, UT on 24 September 2008. Notes of IYSV symptoms on green foxtail were made only on the two grass plants sampled. Density of green foxtail in the weed trial was low and was not recorded. Leaves on both plants displayed a range of symptoms that included streaking, purpling, and chlorotic and necrotic lesions along leaf margins oriented along the axis of longitudinal venation. Samples were positive for IYSV by double-antibody sandwich-ELISA with a commercially available kit (Agdia Inc., Elkhart, IN). ELISA values of the grass samples were 2.64 and 2.23 for each plant sampled. Negative and positive control readings were 0.24 and 4.33, respectively. All absorbance readings were made at 405 nm. To provide a contrast of the grass data in context to the onion field where the weed trial was located, final visual assessments of onions in the field were made on 4 September 2009. Approximately 300 onion plants were assessed for incidence and severity of disease. Incidence of the disease among onions was 100% and the severity of iris yellow spot on leaves was 20 lesions per leaf. The average ELISA value over 30 individual onions arbitrarily sampled from the field on the same day was 3.50, and the ELISA values among the samples ranged from 1.37 to 4.38. The negative and positive controls were 0.19 and 4.40, respectively. To further verify the presence of IYSV in the grass specimen, reverse transcription-PCR was performed on total nucleic acid extracts obtained from the symptomatic parts of the leaves. Primers specific to the nucleocapsid (N) gene coded by the small (S)-RNA of IYSV were used (3). The forward and reverse primer pairs, 5'-TCAGAAATCGAGAAACTT-3' and 5'-CACCAATGTCTTCAACAATCTT-3', respectively, amplify a 751-nt fragment of the N gene (3). An amplicon of expected size was obtained, cloned, and sequenced. The nucleotide sequence analysis and comparison with known IYSV S-RNA sequences showed that the amplicon from foxtail (GenBank Accession No. FJ652594) samples had the highest nucleotide sequence identity (98%) with the corresponding region of an IYSV isolate from Jefferson County, OR (GenBank Accession No. DQ233479). To our knowledge, this is the first report of natural infection of a grass species by IYSV and the first report of a Tospovirus infecting a grass species. The data suggests grasses may serve as a new host reservoir for IYSV. The increasing number of weed hosts of IYSV warrants further study on the role of these weeds as hosts for onion thrips and in IYSV epidemiology. References: (1) D. Gent et al. Plant Dis. 90:1468, 2006. (2) C. Nischwitz et al. Plant Dis. 91:1518, 2007. (3) H. R. Pappu et al. Arch. Virol. 151:1015, 2006. (4) R. Sampangi et al. Plant Dis. 91:1683, 2007.

Natural Infection of Iris yellow spot virus in Twoscale Saltbush (Atriplex micrantha) Growing in Utah

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) continues to be an economically important pathogen affecting onion bulb and seed production in several parts of the world and the United States (1). Several weeds were reported naturally infected with IYSV (1,2,4). Leaves of Atriplex micrantha Ledeb. (synonym A. heterosperma Bunge) were collected from naturally occurring plants in a weed trial conducted in commercial onions grown in Box Elder County, UT on 24 September 2008. Leaves displayed a range of symptoms including spotting, chlorosis, and necrosis. Symptomatic leaves were preferentially selected for subsequent diagnostic analyses. Samples were positive for IYSV when tested by double-antibody sandwich-ELISA using a commercially available kit (Agdia Inc., Elkhart, IN). For further confirmation, total nucleic acid extracts from the symptomatic parts of the leaves were prepared and tested for the presence of IYSV by reverse transcription-PCR with primers specific to the nucleocapsid (N) gene coded by the small (S)-RNA of IYSV. The forward and reverse primer pair, 5'-TCAGAAATCGAGAAACTT-3' and 5'-CACCAATGTCTTCAACAATCTT-3', respectively, amplifies a 751-nt fragment of the N gene (3). An amplicon of expected size was obtained, cloned, and sequenced. The nucleotide sequence analysis and comparison with known IYSV S-RNA sequences showed that the sequence of the amplicon from A. micrantha (GenBank Accession No. FJ493541) shared more than 84% nt sequence identity with the corresponding region of IYSV isolates available in GenBank, confirming the IYSV infection of the new host weed. The highest sequence identity (98%) was with an IYSV isolate from Jefferson County, OR (GenBank Accession No. DQ233479). To our knowledge, this is the first report of IYSV infection of A. micrantha under natural conditions. The role of A. micrantha and other weeds in IYSV epidemiology needs further investigation. References: (1) D. Gent et al. Plant Dis. 90:1468, 2006. (2) C. Nischwitz et al. Plant Dis. 91:1518, 2007. (3) H. R. Pappu et al. Arch. Virol. 151:1015, 2006. (4) R. Sampangi et al. Plant Dis. 91:1683, 2007.

Rapid small-animal dual-energy X-ray absorptiometry using digital radiography

Although dual-energy X-ray absorptiometry (DEXA) is an established technique for clinical assessment of areal bone mineral density (BMD), the spatial resolution, signal-to-noise ratio, scan time, and availability of clinical DEXA systems may be limiting factors for small-animal investigations using a large number of specimens. To avoid these limitations, we have implemented a clinical digital radiography system to perform rapid area DEXA analysis on in vitro rat bone specimens. A crossed step-wedge (comprised of epoxy-based materials that mimic the radiographic properties of tissue and bone) was used to calibrate the system. Digital radiographs of bone specimens (pelvis, spine, femur, and tibia from sham-ovariectomized [SHAM] and ovariectomized [OVX] rats) were obtained at 40 kilovolt peak (kVp) and 125 kVp, and the resulting areal BMD values were compared with those obtained with a clinical fan-beam DEXA system (Hologics QDR 4500). Our investigation indicates that the cross-wedge calibrated (CWC) DEXA technique provides high-precision measurements of bone mineral content (BMC; CV = 0.6%) and BMD (CV = 0.8%) within a short acquisition time (<30 s). Areal BMD measurements reported by the CWC-DEXA system are within 8.5% of those reported by a clinical fan-beam scanner, and BMC values are within 5% of the known value of test specimens. In an in vivo application, the CWC-DEXA system is capable of reporting significant differences between study groups (SHAM and OVX) that are not reported by a clinical fan-beam DEXA system, because of the reduced variance and improved object segmentation provided by the CWC-DEXA system.

Simultaneous MRI measurement of blood flow, blood volume, and capillary permeability in mammary tumors using two different contrast agents

A technique for the simultaneous measurement of three vascular parameters: blood flow (Frho), blood volume (v(b)), and the capillary permeability-surface area product (PSrho) in breast tumors using dynamic contrast-enhanced magnetic resonance imaging (MRI) is presented. Features of the technique include measurement of precontrast tumor T(1), rapid temporal sampling, measurement of the arterial input function, and use of a distributed parameter tracer kinetic model. Parameter measurements are compared that were determined using two contrast agents of different molecular weights, gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA; 0.6 kDa) and Gadomer-17 (17 kDa), in 18 spontaneous canine mammary tumors. Measurements of Frho and v(b) corresponded well with literature values, and the mean PSrho measured using Gd-DTPA was a factor of 15 higher than that measured using Gadomer-17. J. Magn. Reson. Imaging 2000;12:991-1003.

Assessment of maintenance therapy with reduced doses of PTH(1-34) in combination with a raloxifene analogue (LY117018) following anabolic therapy in the ovariectomized rat

This experiment was designed to evaluate the ability of a raloxifene analogue (RA), LY117018, with or without reduced dosing of human parathyroid hormone (hPTH)(1-34) to maintain gains in bone mass after a fully anabolic treatment regimen given to aging osteopenic rats. Six-month-old rats were ovariectomized (ovx) or sham-operated (sham). After 1 month, ovx rats were treated with an anabolic regimen consisting of subcutaneous hPTH(1-34) 80 microg/kg/day and oral raloxifene 3 mg/kg/day, each given 5 days/week for 3 months. Thereafter, the treated ovx rats went on to an 8 week maintenance phase of treatment with either RA alone at the same dose, hPTH(1-34) at a reduced dosing interval (twice a week), or a combination of the two. Bone mineral density (BMD) was measured ex vivo at four skeletal sites, lumbar spine (L2-4), proximal hemipelvis, whole femur, and tibia, by dual-energy X-ray densitometry. All four sites showed a similar pattern of response. After the 3 month anabolic phase, the sham group had significantly higher BMD values than ovx rats at all skeletal sites (p < or = 0.002). The ovx rats treated with PTH + RA during the anabolic phase of the protocol had significantly higher BMD than the sham group in the femur, tibia, and spine (p < or = 0.02) and higher but not significantly different values in the pelvis. Following the 2 month maintenance phase, comparisons were made with the PTH-RA group at the end of the anabolic phase. Decrements in BMD were seen in all three maintenance therapy groups, but they were not statistically significant in the RA plus reduced PTH dose group. However, reduced hPTH(1-34) dosing and RA alone resulted in significant reductions of bone mass measurements at several skeletal sites during the maintenance phase. We conclude that the raloxifene analogue LY117018 may be useful in maintaining bone mass in aging ovx rats following anabolic therapy with hPTH(1-34) and raloxifene analogue, but that this strategy only allows for dose reduction of hPTH(1-34) rather than its discontinuation.

The addition of a raloxifene analog (LY117018) allows for reduced PTH(1-34) dosing during reversal of osteopenia in ovariectomized rats

To test the hypothesis that an antiresorptive agent might reduce the dosing requirement for an anabolic drug during reversal of osteopenia due to estrogen deficiency, the following experiment was conducted in 6-month-old female rats. Ovariectomy or sham surgery was performed and the following six experimental groups were studied. Untreated (SHAM) or ovariectomized (OVX) animals served as control groups. Four weeks post-OVX, osteopenic rats (now 7 months old), were treated in one of four experimental protocols: human parathyroid hormone (hPTH(1-34)), 80 microg/kg/day, given by subcutaneous injection 5 days/week; a selective estrogen receptor modulator (SERM), raloxifene analog LY117018 (RA), 3 mg/kg/day, given by gavage 5 days/week; and two combinations of LY117018 at the same dose and frequency with hPTH(1-34) (same dose, 5 times/week) and a reduced dosing interval of hPTH(1-34) (same dose, 2 times/week). After 12 weeks of treatment, the four experimental groups were sacrificed at age 10 months. SHAM and OVX controls were also studied at 7 and 10 months of age. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry at four skeletal sites: two mixed cortical/trabecular sites (femur and tibia) and two predominantly trabecular sites (lumbar spine and pelvis). The differences in BMD were consistent at all four sites. RA alone maintained BMD at all skeletal sites, but the results were not significantly improved over OVX controls, at age 10 months. hPTH(1-34) injections given 5 days/week resulted in BMD increments significantly higher than in either OVX or SHAM controls (p < 0.001). While the RA did not enhance the anabolic effects of full doses of hPTH(1-34), the addition of RA treatment to twice-weekly hPTH(1-34) dosing resulted in BMD increments at all four skeletal sites that were similar to the more intensive anabolic regimen of hPTH(1-34) therapy given 5 times/week. Therefore, an antiresorptive agent such as SERMs may potentially reduce the pharmacologic doses of PTH needed to reverse estrogen deficiency-induced osteopenia.

A randomized controlled trial to compare the efficacy of cyclical parathyroid hormone versus cyclical parathyroid hormone and sequential calcitonin to improve bone mass in postmenopausal women with osteoporosis

Short cycles of human (h) PTH-(1-34) may have an anabolic effect to increase bone mass in patients with osteoporosis. As PTH also stimulates bone resorption, it is theoretically possible to enhance the anabolic effects of PTH by using a sequential antiresorptive agent in the treatment cycle. To test this hypothesis, 30 women with osteoporosis, aged 67 +/- 8 yr, completed a 2-yr protocol that comprised 28-day courses of hPTH-(1-34) (800 U) given by daily sc injections; each course was repeated at 3-month intervals. By random allocation, patients either received sequential calcitonin (CT) immediately following the cycle of hPTH-(1-34) (75 U/day, sc; PTH + CT; n = 16) or placebo CT (PTH alone; n = 14) for 42 days. Baseline bone mineral density (BMD) at the lumbar spine site revealed t scores of -3.7 +/- 1.2 (+/-SD) for the PTH alone group and -3.0 +/- 1.4 for the PTH + CT groups, who had 2.0 +/- 2.3 and 1.8 +/- 2.4 vertebral fractures, respectively, at entry to the study. At the end of the 2 yr, the lumbar spine BMD increased from 0.720 +/- 0.130 to 0.793 +/- 0.177 g/cm2 (10.2%) in the PTH group and from 0.760 +/- 0.168 to 0.820 +/- 0.149 g/cm2 (7.9%) in the PTH + CT group. These changes were significant over time in both groups (P < 0.001). Although the final 2-yr lumbar spine BMD was not significantly different between the two treatment groups, those patients receiving sequential CT injections gained bone mass at a consistently slower rate. Changes in BMD at the femoral neck averaged +2.4% and -1.8% in the PTH and PTH + CT groups, respectively, neither of which was significant. In the group receiving only cyclical hPTH-(1-34), the observed 2-yr vertebral fracture incidence was 4.5 compared to 23.0/100 patient yr in the PTH + CT group (P = 0.078). During the first two cycles, changes in biochemical markers of bone formation (serum total alkaline phosphatase, bone-specific alkaline phosphatase, and osteocalcin) and bone resorption (fasting urinary hydroxyproline and N-telopeptide excretion) were significantly increased over pretreatment values after 28 days of hPTH-(1-34) injections (P < 0.05 to P < 0.01 for both groups). Even end of cycle values remained elevated over the study baseline across time (P < 0.01). There were no significant differences for any outcome parameter between the two treatment groups. We conclude that short cycles (28 days) of daily hPTH-(1-34) injections result in significant increases in lumbar spine BMD, without significant changes in cortical bone mass at the femoral neck. Very low incident vertebral fracture rates were documented over 2 yr. However, there is no evidence that sequential antiresorptive therapy with CT is of any benefit over that conferred by cyclical PTH alone.

31P magnetic resonance spectroscopy studies in schizophrenia

Phospholipid metabolism abnormalities have been suggested by a number of postmortem brain and red blood cell studies in schizophrenia. 31P magnetic resonance spectroscopy enables the examination of phospholipid metabolism in living patients. These in vivo studies have demonstrated that schizophrenic patients have lower prefrontal levels of phosphomonoesters and higher levels of phosphodiesters compared to matched controls. Patients with psychotic depression also seem to show lower levels of phosphomonoesters compared to controls. This suggests that membrane phospholipid differences may not be specific to schizophrenia. Preliminary 31P magnetic resonance spectroscopy studies at high field strength on postmortem temporal lobe samples show no differences between treated schizophrenic patients and controls for phosphoethanolamine and phosphocholine which are the main constituents of the phosphomonoester peak. Further studies are underway in the prefrontal region. While 31P magnetic resonance spectroscopy studies have demonstrated membrane phospholipid abnormalities in schizophrenia, it is not clear whether these findings are specific to schizophrenia or part of a generalized membrane phospholipid abnormality.

Bone mineral density and the risk of fracture in patients receiving long-term inhaled steroid therapy for asthma

To determine whether high-dose or prolonged inhaled steroid therapy for asthma increases a patient's risk of osteoporosis and fracture, we measured bone density in 26 men and 43 women (41 postmenopausal, all of whom had received supplemental estrogen therapy) after treatment with an inhaled steroid for 10.1 +/- 5.5 years and oral prednisone for 10.7 +/- 9.7 years (mean +/- SD). Most had stopped receiving prednisone since commencing the inhaled steroid therapy. We found that bone densities (adjusted for age and sex to yield a z score) were lower in association with higher daily doses of inhaled steroid (p = 0.013 ANCOVA) and with the duration of past prednisone therapy (p = 0.032). Larger cumulative inhaled steroid doses were associated with higher bone densities (p = 0.002) and a reduction in the numbers of patients at risk of fracture. Bone density also increased with the amount of supplemental estrogen therapy (p = 0.058) and, at equivalent levels of inhaled and oral steroid use, women showed higher bone density z scores than did men. Women with a lifetime dose of inhaled steroid greater than 3 gm had normal bone density regardless of the amount of past or current prednisone use or the current dose of inhaled steroid. These data indicate that the daily dose, but not the duration, of inhaled steroid therapy may adversely affect bone density, and that estrogen therapy may offset this bone-depleting effect in postmenopausal women.

A questionnaire to evaluate disability in osteoporotic patients with vertebral compression fractures

BACKGROUND

Few studies have reported on the functional disability due to vertebral compression factors in osteoporosis. The Osteoporosis Functional Disability Questionnaire (OFDQ) was developed to assess disability in patients with osteoporosis and back pain due to vertebral fractures. The domains of the OFDQ include: quantitative indices of pain, a standard 20-item depression scale, 26 items relating to functional abilities, a scale of social activities, and confidence in the ability of prescribed osteoporosis treatment to reverse disability.

METHODS

Reliability of the OFDQ was assessed using test-retest and internal consistency methods. Criterion validity was demonstrated by correlating disability against radiographic evidence of vertebral fractures. Construct validity was demonstrated through comparisons of 81 patients with osteoporosis and fractures to 37 healthy age-matched controls. Additional evidence was found in comparing 45 of the 81 cases who were actively engaged in an exercise program with 36 cases who were sedentary.

RESULTS

The test-retest reliabilities ranged from .76 to .93, with internal consistencies from .57 to .96. The OFDQ correlated significantly with relevant spinal pathology, and showed significant improvements in activities of daily living and socialization when active exercisers were compared to inactive patients with osteoporosis.

CONCLUSIONS

The OFDQ is a reliable instrument which correlates well with objective measures of osteoporotic spinal damage. It is also sensitive to changes in disability brought about by participation in our aerobic exercise program. The OFDQ may be a useful adjunct to measuring outcomes in other osteoporotic treatment protocols.

Measurement of the extraction efficiency and distribution volume for Gd-DTPA in normal and diseased canine myocardium

We have previously shown that the myocardial Gd-DTPA concentration ([Gd-DTPA]t(t)) after a bolus injection of Gd-DTPA can be predicted by the Modified Kety Equation (MKE). If [Gd-DTPA]t(t) can be determined by MRI and the data fit to the MKE, then the distribution volume (lambda) of Gd-DTPA and the myocardial flow (F) times the extraction efficiency (E), i.e., the FE product, can be determined. Therefore F can only be quantified if E is known. We measured the global E in vivo in normal canine myocardium, and measured E and lambda, in vitro, locally in normal, acute ischemic (n = 5; coronary artery occlusion < 4 h), infarcted (n = 4; coronary artery occlusion, 6 days) and reperfused (n = 4; coronary artery occlusion 2 h, and reperfusion 2 h and 6 days) myocardium. Results indicate that E differs with F and with individuals and consequently, F cannot be quantified using the MKE unless the local E is also determined in vivo.

Frontal, temporal, and striatal proton relaxation times in schizophrenic patients and normal comparison subjects

Spin-lattice (T1) and spin-spin (T2) magnetic resonance relaxation times were examined in frontal, temporal, and striatal regions of 24 patients with schizophrenia and 10 normal comparison subjects. The schizophrenic patients had more prolonged T2 values than did the comparison subjects, particularly in the left temporal cortex and white matter, suggesting tissue pathology.

Magnetic resonance imaging increases the blood-brain barrier permeability to 153-gadolinium diethylenetriaminepentaacetic acid in rats

In a qualitative electron microscopy study we initially reported that exposure of rats to a standard clinical magnetic resonance imaging (MRI) procedure temporarily increased the blood-brain barrier (BBB) permeability to horseradish peroxidase. In this study, we quantitatively support our initial finding. Rats were injected intracardially with radio-labelled diethylenetriaminepentaacetic acid [( 153Gd]DTPA) in the middle of two sequential 23.2 min MRI exposures. Exposed rats (n = 21) showed significantly greater (29%, P = 0.006) retention of [153 Gd]DTPA than sham-exposed rats (n = 22) 1 h after the end of the last 23.2 min exposure. These findings suggest that magnetic fields may alter BBB permeability.

Factors influencing the caffeine test for cytochrome P 448-dependent liver function

Liver functions in patients with liver disease can be estimated by caffeine clearance. Our data, however, demonstrate the additional influence of factors other than liver disease on the caffeine test. Smoking enhances caffeine clearance in both healthy volunteers and patients with severe hepatic disorders, whereas co-medication with mexiletine strongly inhibits caffeine elimination.