Supplementation of organic and inorganic selenium to late gestation and early lactation beef cows effect on cow and preweaning calf performance

Angus × Simmental cows ( = 48; BW = 595 ± 17.4 kg, BCS = 5.26 ± 0.05, and age = 2.3 ± 0.07 yr), pregnant with male fetuses, were used to determine the effect of Se source during the last 80 d of gestation and first 108 d of lactation on cow and calf performance. At 203 d in gestation, cows were blocked by BW, breed composition, age, and calf sire and randomly allotted to organic Se, inorganic Se, or no Se treatments. Diets contained corn silage, corn stover, haylage, dried distillers' grains with solubles, and minerals and were formulated to contain 10.4% CP and 0.90 Mcal/kg NEg during gestation and 12.1% CP and 1.01 Mcal/kg NEg during lactation. Diets were fed daily as a total mixed ration and none, 3 mg/d Se as sodium selenite, or 3 mg/d Se as Sel-Plex were top-dressed daily. At 68 d postpartum (DPP), milk production was calculated using the weigh-suckle-weigh procedure and a milk sample was collected to determine composition. At 108 DPP, cow-calf pairs were commingled until weaning at 210 DPP. Cow BW and BCS ( ≥ 0.56) did not differ between treatments at any time point during the study. Milk production, milk fat, and total solids ( ≥ 0.38) did not differ among treatments. Milk protein tended to increase in cows fed inorganic Se compared with cows fed organic Se ( = 0.07) and milk lactose tended to be greatest in cows fed organic Se ( = 0.10). Conception to AI and overall pregnancy rates did not differ between treatments ( ≥ 0.39). Calf weights and ADG did not differ through 108 DPP ( ≥ 0.77) or for the preweaning period ( ≥ 0.33). Plasma Se concentration was adequate for all cows and did not differ among treatments for cows ( ≥ 0.37) or calves ( ≥ 0.90). Liver Se concentrations in cows fed inorganic or organic Se were greater than in control cows ( < 0.01). Longissimus muscles biopsies taken from progeny at 108 DPP also did not differ between treatments ( = 0.45). In conclusion, dietary Se source did not affect cow performance, milk production, or reproductive efficiency. Organic Se decreased milk protein and increased milk lactose but did not alter preweaning performance of progeny from Se-adequate cows.

Relationships between residual feed intake and hepatic mitochondrial function in growing beef cattle

The objective of this study was to evaluate the relationship between hepatic mitochondrial function and residual feed intake (RFI) in growing beef cattle. In Trial 1, RFI was measured in 29 Angus heifers (initial BW = 258.0 ± 24.9 kg) from divergent IGF-I selection lines created at the Eastern Agricultural Research Station (The Ohio State University) fed a grain-based diet (calculated ME = 2.85 Mcal/kg DM). In Trial 2, RFI was measured in 119 Santa Gertrudis steers (initial BW = 308.4 ± 28.1 kg) fed a roughage-based diet (calculated ME = 2.21 Mcal/kg DM). At the end of the RFI measurement period, cattle in Trial 1 (n = 7 low RFI and n = 7 high RFI) and in Trial 2 (n = 6 low RFI and n = 8 high RFI) with measures of RFI exceeding 0.5 (Trial 1) or 1.0 (Trial 2) SD from the mean RFI were selected to measure mitochondrial function. Overall ADG, DMI, and RFI were 1.19 ± 0.15, 9.31 ± 1.12, and 0.00 ± 0.63 kg/d and 0.83 ± 0.16, 9.48 ± 1.00, and 0.00 ± 0.86 kg/d in Trial 1 and 2, respectively. Cattle with low RFI consumed 13 and 24% less (P < 0.05) DM and had 14 and 56% greater (P < 0.05) G:F than cattle with high RFI in Trial 1 and 2, respectively, even though ADG and BW were similar (P > 0.10). In Trial 1, cattle with low RFI tended (P = 0.06) to have greater state 3 respiration rates than cattle with high RFI, but state 3 respiration rates were similar (P > 0.10) between cattle with low and high RFI in Trial 2. In both trials, cattle with low RFI had greater (P < 0.05) acceptor control ratios than their high RFI counterparts. The respiratory control ratio tended (P = 0.09) to be greater for cattle with low RFI compared with high RFI cattle in Trial 1, but no difference (P > 0.10) was observed in Trial 2. Proton-leak kinetics were similar (P > 0.05) between cattle with low and high RFI in both trials. These data suggest that ADP has greater control of oxidative phosphorylation in liver mitochondrial of cattle with low RFI compared to their high RFI counterparts.

Recovery of insulin sensitivity in mature horses after a 3 week course of dexamethasone therapy

REASONS FOR PERFORMING THE STUDY

Dexamethasone is an anti-inflammatory drug commonly used in equine medicine. Insulin sensitivity decreases with prolonged dexamethasone administration, but little information is available about the duration of this side effect after long-term treatment ends.

OBJECTIVES

To determine how long it takes for blood glucose, insulin and markers of insulin sensitivity to return to normal ranges after extended dexamethasone treatment has ceased.

STUDY DESIGN

Experimental study.

METHODS

Eight healthy, mature, mixed-breed horses received 0.04 mg/kg bwt/day oral dexamethasone for 21 days. Blood samples were taken weekly during dexamethasone treatment (Days -21, -14 and -7). Following the final dose of dexamethasone on Day 0, blood samples were taken on Days 1-6, 8, 10, 12, 15 and 22. Day -21 represents baseline or normal blood predexamethasone.

RESULTS

On Day 1, plasma glucose and insulin concentrations and the modified insulin-to-glucose ratio (a proxy for pancreatic β cell responsiveness) were higher and the reciprocal of the square root of insulin (a proxy for the estimate of insulin sensitivity) was lower, in comparison with Day -21 values. Blood glucose concentrations dropped and returned to Day -21 values by Day 2. Insulin concentrations remained elevated until Day 3. Values for the modified insulin-to-glucose ratio decreased and returned to Day -21 concentrations by Day 4. Values for the reciprocal of the square root of insulin did not return to Day -21 values until Day 15.

CONCLUSIONS

These results indicate that, in contrast to blood glucose concentrations, which return to normal quickly (within 2 days after treatment ends), the pancreatic insulin-secreting response has a delayed recovery.

Organic trace mineral levels in the first 96-h post-hatch impact growth performance and intestinal gene expression in broiler chicks

Alterations in nutrient intake in the avian neonatal posthatch period can impact development, performance, and metabolism in adulthood. Very little is known about how mineral levels during the post-hatch period affect or “program” gene expression patterns later in life. The objective of this study was to determine the effect of post-hatch (0 to 96 h) dietary mineral supplementation on performance, tissue mineral content, and intestinal gene expression profiles in 21-day-old broiler chicks. One-day-old chicks were randomly assigned to one of two treatment groups consisting of N (organic Zn, Cu, and Mn provided at 100 % of recommendations (National Research Council 1994)) and/or L (organic Zn, Cu, and Mn provided at 20 % of recommendations (National Research Council 1994)) diets fed in two intervals (days 1–4, days 5–21) as follows: (1)N–Lor (2)L–L. Performance parameters did not differ between treatments except that body weight gain was greater (P < 0.05) in L–L birds than N–L birds over the experimental period. Bone mineral content was similar for both treatments at day 21. Intestinal gene expression profiling was examined using the Affymetrix GeneChip Chicken genome array. Ingenuity pathway analysis revealed differences in gene expression profiles between N and L treatments at day 5. At day 21, profiles were unique between N–L and L–L, suggesting that the diet fed until day 4 had an impact on gene expression patterns at day 21 even when birds were fed the same diets day 5–day 21. In this study, we demonstrated that diets fed for the 96 h post-hatch had long-term effects on gene expression, providing unique information as to why post-hatch diets are so important for the longterm bird health and productivity.

Comparison of gene expression profiles of the jejunum of broilers supplemented with a yeast cell wall-derived mannan oligosaccharide versus bacitractin methylene disalicylate

1. The addition of yeast cell wall (YCW) mannan fractions or low concentrations of antibiotics to the diet of broilers positively affects gut health by improving intestinal cell morphology and improves feed efficiency and performance; however the exact mechanisms are unclear. Based on these production responses, the objective of this study was to compare the effects of supplementing YCW and bacitracin methylene disalicylate (BMD) in the diet on mRNA levels in the jejunum of 6-week-old broilers. 2. Dietary treatments were a maize-soya control diet and the control diet with the addition of YCW or BMD. Birds (n = 7) from each dietary treatment were randomly selected and killed at d 42. Whole jejunum (with serosa) samples were collected for RNA isolation. Gene expression analysis was performed using the AffymetrixGeneChip Chicken Genome Array (Santa Clara, CA, USA). 3. Supplementation with YCW resulted in 928 genes that were significantly changed (456 down-regulated, 472 up-regulated) and supplementation with BMD resulted in 857 genes that significantly changed (408 down-regulated, 449 up-regulated). In addition, 316 genes were significantly changed by both YCW and BMD (146 down-regulated, 170 up-regulated). 4. BMD increased the expression of genes involved in lipid and carbohydrate metabolism and decreased expression of genes associated with T-helper cell pathways. Gene expression profiles from birds fed on diets containing YCW showed changes on a genomic level that correspond to slower gut cell turnover and therefore increased energy preservation for growth. 5. In conclusion, supplementation with BMD or YCW had similar influences on the number of differentially expressed genes in the jejunum. Biological functions common to both YCW and BMD with positive activation scores included antiviral response and antimicrobial response. Genes that were affected by BMD or YCW classified into both different and common biological functions and pathways related to improved metabolism and health in the jejunum.

Antibodies to heteromeric glycolipid complexes in multifocal motor neuropathy

BACKGROUND

Measurement of anti-GM1 IgM antibodies in multifocal motor neuropathy (MMN) sera is confounded by relatively low sensitivity that limits clinical usefulness. Combinatorial assay methods, in which antibodies react to heteromeric complexes of two or more glycolipids, are being increasingly applied to this area of diagnostic testing.

METHODS

A newly developed combinatorial glycoarray able to identify antibodies to 45 different heteromeric glycolipid complexes and their 10 individual glycolipid components was applied to a randomly selected population of 33 MMN cases and 57 normal or disease controls. Comparison with an enzyme-linked immunosorbent assay (ELISA) was conducted for selected single glycolipids and their complexes.

RESULTS

By ELISA, 22/33 MMN cases had detectable anti-GM1 IgM antibodies, whereas 19/33 MMN samples were positive for anti-GM1 antibodies by glycoarray. Analysis of variance (anova) revealed that of the 55 possible single glycolipids and their 1:1 complexes, antibodies to the GM1:galactocerebroside (GM1:GalC) complex were most significantly associated with MMN, returning 33/33 MMN samples as positive by glycoarray and 29/33 positive by ELISA. Regression analysis revealed a high correlation in absolute values between ELISA and glycoarray. Receiver operator characteristic analysis revealed insignificantly different diagnostic performance between the two methods. However, the glycoarray appeared to offer slightly improved sensitivity by identifying antibodies in four ELISA-negative samples.

CONCLUSIONS

The use of combinatorial glycoarray or ELISA increased the diagnostic sensitivity of anti-glycolipid antibody testing in this cohort of MMN cases, without significantly affecting specificity, and may be a useful assay modification for routine clinical screening.

Effects of organic and inorganic dietary selenium supplementation on gene expression profiles in oviduct tissue from broiler-breeder hens

Selenium (Se) is an essential component of at least 25 selenoproteins involved in a multitude of physiological functions, including reproduction. However, relatively little is known about the mechanisms by which Se exerts its physiological effects in reproductive tissue. The objective of this study was to compare the effect of long-term inorganic Se (sodium selenite, SS) and organic yeast-derived Se (Sel-Plex(®), SP) supplementations on tissue Se content and gene expression patterns in the oviduct of broiler-breeder hens. Hens were randomly assigned at 6 weeks of age to one of the three treatments: basal semi-purified diet (control), basal diet+0.3 ppm Se as SP or basal diet+0.3 ppm Se as SS. At 49 weeks, oviduct tissue from hens randomly selected from each treatment (n=7) was analyzed for Se content and gene expression profiles using the Affymetrix Chicken genome array. Gene expression data were evaluated using GeneSpring GX 10.0 (Silicon Genetics, Redwood, CA) and Ingenuity Pathways Analysis software (Ingenuity Systems, Redwood City, CA). Oviduct Se concentration was greater with Se supplementation compared with the control (P≤0.05) but did not differ between SS- and SP-supplemented groups. Gene expression analysis revealed that the quantity of gene transcripts associated with energy production and protein translation were greater in the oviduct with SP but not SS supplementation. Targets up-regulated by SP, but not SS, included genes encoding several subunits of the mitochondrial respiratory complexes, ubiquinone production and ribosomal subunits. SS hens showed a decrease in transcripts of genes involved in respiratory complexes, ATP synthesis and protein translation and metabolism in oviduct relative to control hens. In this study, although tissue Se concentrations did not differ between hens fed SS- and SP-supplemented diets, expression patterns of genes involved in energy production and protein synthesis pathways differed between treatments. These variations may partially explain the differences in reproductive performance reported in hens fed different forms of Se.

A comparative transcriptomic study of vitamin E and an algae-based antioxidant as antioxidative agents: investigation of replacing vitamin E with the algae-based antioxidant in broiler diets

Previous study indicated that inclusion of an algae-based antioxidant as an antioxidative agent [EconomasE, Alltech, Nicholasville, KY; EcoE] significantly reduced the amount of vitamin E (VE) required in broiler diets without compromising performance and meat quality. To assess the mechanisms related to the VE-saving activity of EcoE, as well as other potential functions related to EcoE and VE supplementation, we analyzed gene expression profiles of breast muscle from broilers fed a control diet, the control diet + 50 IU of VE/kg, the control diet + 100 IU of VE/kg, or the control diet + 200 g of EcoE/ton. Evaluation of the serum antioxidant capacity indicated that dietary supplementation of either a high level of VE (50 or 100 IU of VE/kg) or EcoE significantly improved bird antioxidant status. Analysis of gene expression profiles indicated that expression of 542 genes of the breast muscle were altered (P < 0.05, fold change >1.2) by dietary treatments, of which a significant part were commonly regulated by EcoE and VE (especially the control diet + 50 IU of VE/kg). In addition to the process of cellular oxidation, gene ontology analysis indicated the involvement of EcoE and VE on cell morphology, skeletal and muscular system development and function, immune response, and multiple metabolic processes, including lipid, carbohydrate, and drug metabolism. Results of this experiment indicate that the biological roles of high VE, including its activity as an antioxidant, can be greatly mimicked at the transcriptional level by EcoE, and they suggest a relationship of functional redundancy between VE and EcoE in the broiler diets.

Expression of the hypothalamic transcription factor Nhlh2 is dependent on energy availability

Mice with a deletion of the hypothalamic basic helix-loop-helix transcription factor Nhlh2 display adult onset obesity, implicating Nhlh2 in the neuronal circuits regulating energy availability. Nhlh2 colocalises with the hypothalamic thyrotrophin-releasing hormone (TRH) neurones in the paraventricular nucleus (PVN) and pro-opiomelanocortin (POMC) neurones in the arcuate nucleus. We show that Nhlh2 expression is significantly reduced in response to 24-h food deprivation in the arcuate nucleus, PVN, lateral hypothalamus, ventromedial hypothalamus (VMH) and dorsomedial hypothalamus (DMH). Food intake for 2 h following deprivation stimulates Nhlh2 expression in the arcuate nucleus and the PVN, and leptin injection following deprivation results in increased Nhlh2 expression in the arcuate nucleus, PVN, lateral hypothalamus, VMH, and DMH. Hypothalamic Nhlh2 expression in response to leptin injection is maximal by 2 h. Following leptin injection, Nhlh2 mRNA colocalises in POMC neurones in the arcuate nucleus and TRH neurones in the PVN. Nhlh2 mRNA expression in POMC neurones in the arcuate nucleus and TRH neurones in the PVN is reduced with energy deprivation and is stimulated with food intake and leptin injection. Modulation of POMC expression in response to changes in energy availability is not affected in mice with a targeted deletion of Nhlh2. However, deletion of Nhlh2 does result in loss of normal TRH mRNA expression in mice exposed to food deprivation and leptin stimulation. These data implicate Nhlh2 as a regulatory target of the leptin-mediated energy availability network of the hypothalamus, and TRH as a putative downstream target of Nhlh2.

Genetic analysis of NHLH2 and its putative role in bovine body weight control

The control of energy balance is fundamental to adult animals and is necessary for weight gain/loss, reproductive capacity and general health. In mice, targeted deletion of the neuronal transcription factor Nhlh2 results in adult-onset obesity because of reduced exercise and infertility because of reduced sexual behaviour. Nhlh2 (NHLH2 for humans) is expressed in the hypothalamus, particularly in neurons that have been shown to regulate energy balance. We have cloned the bovine Nhlh2 gene (bNHLH2) and we have shown that bNHLH2 is also expressed in the hypothalamus. Phylogenetic analysis of Nhlh2 reveals that it is very highly conserved in humans, mice, chimps and cattle, and found in organisms with simpler nervous systems, including Caenorhabditis elegans and Drosophila. Using a cattle-human comparative map and online databases, we have evidence that bNHLH2 is located near a quantitative trait locus for marbling on bovine chromosome 3 between microsatellite markers BM723 and BMS963. Cloning of the bNHLH2 gene from Holstein cattle and a mixed breed individual and comparison with Hereford sequences shows that the gene is highly conserved among bovine breeds.

Building a vision for the future: strategic planning in a shared governance nursing organization

Today's health care delivery environment is marked by extreme turbulence and ever-increasing complexity. Now, more than ever, an organization's strategic plan must do more than outline a business plan. Rather, the strategic plan is a fundamental tool for building and sustaining an organizational vision for the future. The strong, dynamic strategic plan (1) represents a long-range vision for improving organizational performance, (2) provides a model for planning and implementing structures and processes for the management of outcomes, (3) reflects and shapes the organizational culture and customer focus, (4) provides decision support for difficult operational choices made day to day, and (5) integrates and aligns the work of the organization. This article describes the development, implementation, and evaluation of a methodology for strategic planning within a shared governance nursing organization. Built upon the strategic plan of the hospital, the process undertaken by the nursing organization reflects the following commitments: (1) to develop a strategic plan that is meaningful and part of daily work life at all levels of the nursing organization, (2) to make the plan practical and realistic through incremental building, (3) to locate and articulate accountability for each step, and (4) to build in a process for checking progress toward goal achievement and readjusting the plan as necessary.

In vivo NMR and MRI using injection delivery of laser-polarized xenon

Because xenon NMR is highly sensitive to the local environment, laser-polarized xenon could be a unique probe of living tissues. Realization of clinical and medical science applications beyond lung airspace imaging requires methods of efficient delivery of laser-polarized xenon to tissues, because of the short spin-lattice relaxation times and relatively low concentrations of xenon attainable in the body. Preliminary results from the application of a polarized xenon injection technique for in vivo 129Xe NMR/MRI are extrapolated along with a simple model of xenon transit to show that the peak local concentration of polarized xenon delivered to tissues by injection may exceed that delivered by respiration by severalfold.

Temperature determination in the frozen region during cryosurgery of rabbit liver using MR image analysis

Cryosurgery currently is being used clinically to treat tumors in internal organs such as the liver and prostate. Although performed at present under ultrasound monitoring, magnetic resonance imaging (MRI)-guidance of these procedures not only permits monitoring of the frozen region during cryosurgery but also makes it possible to determine the temperature distribution in the frozen region, which is not possible using ultrasound monitoring. A good estimate of the region of destruction in the tissue can be obtained from correlating the temperature distribution and the time course of the freezing with the image of the frozen region. Unfortunately, MR pulse sequence-based temperature determination techniques such as diffusion, relaxation time, and chemical shift cannot be used for measuring the temperature in the frozen region because the T2 of the frozen regions is so short that there is effectively no RF signal from the frozen region. This paper describes a numerical technique for determining the two dimensional temperature distribution in the frozen region during MR image-guided cryosurgery of normal liver in rabbits. The technique involves solving the energy equation numerically in the frozen region to determine the temperature distribution there. The boundary conditions needed to solve the equation are determined from MR images of the frozen tissue during cryosurgery and from the measured temperature of the cryoprobe. The calculated temperature in the frozen region is then correlated with the damaged region (cryolesion) determined from post mortem histologic evaluation.

Advances in positron tomography for oncology

Development of PET instrumentation over the past 42 years has moved from simple dual-detector coincidence scanners, to proposed systems having 60,000 detectors and simultaneous coverage of 15-cm regions of the body with spatial resolutions better than 4 mm. The principal determinants of positron emission tomography (PET) instrumentation advances are positron range, noncollinearity of the annihilation photons, scattering, random event rates, detector size, efficiency, speed and light output; capability to correct for depth of crystal interaction, attenuation compensation, axial coverage, and rapid data analysis and presentation. While general-purpose systems with 2-mm resolution are expected, special-purpose PET devices are being built for breast and brain tumor studies with resolutions from 1.7 to 5 mm.

Iodine-123-5-iodo-6-nitroquipazine: SPECT radiotracer to image the serotonin transporter

Because serotonergic function has been implicated in the pathophysiology of a number of diseases of the nervous system, efforts to image this system in vivo have received considerable recent attention. Promising preliminary results with the tracer 5-iodo-6-nitroquipazine (INQUIP) have prompted us to perform further studies designed to validate the use of the tracer as an in vivo ligand for the serotonin transporter.

METHODS

We studied six adult macaca mulatta in eight experiments which involved SPECT imaging at 17 to 24 hr post-tracer injection, including three experiments with coinjection of the 123I-and 125I-radiolabeled tracer for direct comparison of autoradiography and SPECT, and three experiments in which animals were lesioned with the serotonergic neurotoxin (+/-)3,4-methyl-enedioxymethamphetamine (MDMA). In addition, we evaluated the metabolism of the tracer in the brain and periphery.

RESULTS

SPECT images obtained at 17 and 24 hr reflected the known pattern of distribution of serotonin transporters and also showed close correspondence to the autoradiograms. Ratios of binding in the brain-stem to binding in the cerebellum were close to 3 at 17 hr. autoradiograms from an MDMA-treated animal showed up to 95% reductions of binding, while the SPECT data showed smaller reductions. Virtually all of the tracer in the brain stem was in the form of unmetabolized parent compound, but plasma showed rapid peripheral metabolism of the tracer.

CONCLUSION

These results demonstrate that INQUIP SPECT images are sensitive measures of in vivo binding to the serotonin transporter, and support the further development of the tracer as a method for the in vivo study of serotonergic neurons in humans.

PET studies of cerebral glucose metabolism in conscious rhesus macaques

A growing body of evidence suggests that rhesus macaques may be a good model of human brain aging. We used positron emission tomography (PET) and 18F-fluorodeoxyglucose (FDG) to measure regional cerebral metabolic rates for glucose (rCMRglc) in young and aged rhesus macaques to determine if age-related decreases, such as those reported in humans, also occur in macaques. Whereas the aged animals had lower metabolic rates in every brain region studied, the largest differences were in left temporal cortex. The largest differences were also observed in left temporal cortex when relative rCMRglc values were used. Both rCMRglc and relative rCMRglc were marked by substantial individual variation within the aged group. This variation may parallel the variation observed in behavioral studies. Future studies that include both PET and behavioral measures should help determine if there is a relationship between age-related changes in rCMRglc and behavior.

A comparison of topical diclofenac with prednisolone for postcataract inflammation

OBJECTIVE

To compare diclofenac sodium with prednisolone acetate for the control of postoperative inflammation after cataract surgery.

DESIGN

Fifty-two patients undergoing phacoemulsification with posterior chamber intraocular lens implantation were randomly assigned to receive either 0.1% diclofenac eye drops or 1% prednisolone eye drops as their postoperative anti-inflammatory medication. The patients were examined 1 day (baseline), 1 week, and 1 month after surgery. Postoperative inflammation was evaluated subjectively by slit-lamp assessment of cell and flare and objectively by measurement of cell and flare with a laser cell and flare meter.

RESULTS

At each visit, there was no statistically significant difference in postoperative inflammation either by slit-lamp assessment or with the laser cell and flare meter for the two treatment groups.

CONCLUSION

In the dosage used, diclofenac was as effective an anti-inflammatory agent for uncomplicated post-cataract inflammation as prednisolone.

Variability and reproducibility of rubidium-82 kinetic parameters in the myocardium of the anesthetized canine

Kinetic analysis of 82Rb dynamic PET data produces quantitative measures which could be used to evaluate ischemic heart disease. These measures have the potential to generate objective comparisons of different patients or the same patient at different times. To achieve this potential, it is essential to determine the variability and reproducibility of the kinetic parameters.

METHODS

A total of 48 82Rb dynamic PET datasets were acquired from two pure bred beagles. Each animal underwent eight 82Rb PET studies with essentially the same protocol for three successive weeks. Data were acquired with the Donner 600-Crystal Positron Tomograph (PET600). In each week, single-slice dynamic 82Rb PET datasets were collected with the animal at rest at three different gantry positions separated by 5 mm. Additional dataset were collected after dipyridamole infusion and after administration of aminophylline to induce a return to rest. A two-compartment kinetic model with correction for myocardial vasculature and spillover from the left ventricular blood pool was used to analyze the dynamic datasets. Model parameters for uptake (k1), washout (k2) and vascular fraction (fv) were estimated in 11-14 myocardial regions of interest (ROIs) using a weighted least-squares criterion. Statistical fluctuation due to the PET acquisition process was minimized by using a relatively high 82Rb dose (about 30 mCi) to take advantage of the high count rate capacity of the PET600.

RESULTS

The variation in mean k1, where the mean is taken over the myocardial ROIs was 10%-20% (Dog 1) and 15%-50% (Dog 2) among the rest studies conducted on the same date. Similar variation was evident in comparing studies in the same animal for different weeks.

CONCLUSION

Spatial and temporal variation in estimates of the uptake rate (k1) of 82Rb in the resting myocardium of the anesthetized canine are small in relation to the functional increase in k1 following dipyridamole infusion.

In vivo imaging of the 5-hydroxytryptamine reuptake site in primate brain using single photon emission computed tomography and [123I]5-iodo-6-nitroquipazine

Previous experiments have demonstrated that 5-iodo-6-nitro-2-piperazinylquinoline (5-I-6-NQP) is a potent and selective ligand for studying brain 5-hydroxytryptamine (5-HT) reuptake sites. We performed in vivo imaging in non-human primates using single photon emission computed tomography (SPECT) and the 123I-labeled compound [123I]5-I-6-NQP. These studies showed rapid brain uptake, with slow egress of the tracer from the brainstem, a region rich in 5-HT reuptake sites. Loss of the tracer from regions with a lower density of these sites, such as cerebellum, was relatively more rapid. Pretreatment of animals with paroxetine increased the washout of tracer from the brainstem to rates similar to that seen in cerebellum. Brainstem to cerebellar ratios of tracer accumulation were > 2 by 8 h after injection, and in paroxetine pretreated animals remained close to 1. These results indicate that the radiotracer has characteristics suitable for use as a SPECT imaging agent of serotonin reuptake sites.

Monitoring cryosurgery in the brain and in the prostate with proton NMR

This brief communication reports the results of preliminary studies performed to evaluate the feasibility of using NMR imaging to monitor the freezing of tissue during cryosurgery. Two tissues were studied, rabbit brain and dog prostate. NMR imaging of these tissues provided a clear distinction between frozen and unfrozen tissue and an accurate assessment of the extent of freezing in real time.

A comparison of topical non-steroidal anti-inflammatory drugs to steroids for control of post cataract inflammation

Fifty patients undergoing phacoemulsification with posterior chamber intraocular lens implantation were randomly assigned to receive either diclofenac sodium 0.1% eye drops (Voltaren Ophthalmic, CibaVision Ophthalmics, Duluth, GA) or prednisolone acetate 1.0% eye drops (Pred Forte, Allergan Pharmaceuticals, Irvine, CA) as their postoperative anti-inflammatory medication. The patients were examined one day, one week, and one month after surgery, and their postoperative inflammation was evaluated both by slit lamp assessment of cell and flare, and by objective measurement of cell and flare with the Kowa FC-1000 laser cell and flare meter. At each visit, the level of postoperative inflammation was the same for the two study groups. Thus diclofenac sodium was as effective an anti-inflammatory agent for postoperative inflammation as prednisolone acetate.

A study of radiation necrosis and edema in the canine brain using positron emission tomography and magnetic resonance imaging

Radiation injury, a major hazard of central nervous system (CNS) radiotherapy, was investigated using sequential studies with positron emission tomography (PET) and magnetic resonance imaging (MRI) in beagle dogs with both helium and neon-ion hemibrain irradiation. All dogs receiving 7.5-11 Gy of neon showed no signs of radiation injury to 3 years after irradiation. Dogs receiving > or = 13 Gy neon or helium succumbed to radiation necrosis and died 21-32 weeks after irradiation. The findings of imaging studies for all dogs who succumbed to radiation necrosis were normal until 3-6 weeks before death. Sequential studies were performed using 0.5 T MRI spin-echo and inversion recovery imaging sequences, and high-resolution (2-3 mm) PET with 18F deoxyglucose and 82Rb. The same axial slices (within 1-2 mm) were imaged repeatedly (weekly) after irradiation until death. The earliest CNS changes were seen as decreased metabolic activity in the cortex of the irradiated hemisphere with PET or an increase in signal intensity in the periventricular white matter on T2-weighted spin-echo imaging on MRI. From the time this increase in signal intensity was first observed, T1 and T2 values increased steadily in both the gray and white matter until death. The changes in white matter were consistently greater than those in gray matter. The results of PET, MRI, and histopathological examinations support the theory that both cellular and vascular mechanisms are involved in radiation necrosis.

MRI-monitored cryosurgery in the rabbit brain

The inability to observe the transient, irregular shape of the frozen region that develops during cryosurgery has inhibited the application of this surgical technique to the treatment of tumors in the brain and deep in visceral organs. We used proton NMR spin-echo and spoiled gradient-echo imaging to monitor the development of frozen lesions during cryosurgery in the rabbit brain and the resulting postcryosurgical changes up to 4 hr after freezing. Spoiled gradient-echo images (TE = 14 ms; TR = 50 ms) were acquired during freezing and thawing at a rate of 15 s/slice. Although the frozen region itself is invisible in MR images, its presence is distinguished easily from the surrounding unfrozen soft tissue because of the large contrast difference between frozen and unfrozen regions. T2-weighted spin-echo images (TE = 100 ms, TR = 2 s) obtained after thawing suggest that edema forms first at the margin of the region that was frozen (cryolesion) and then moves into the region's core. Histological examination showed complete necrosis in the cryolesion and a sharp transition to undamaged tissue at the margin of the lesion and its image. Blood-brain barrier (BBB) damage was investigated using gadolinium-DTPA. The region of edema in the T2-weighted spin-echo images was coincident with the area of BBB damage in the Gd-DTPA-enhanced T1-weighted spin-echo images (TE = 33 ms, TR = 400 ms) and both were distinguishable as areas of high signal relative to the surrounding normal tissue. The results of these experiments indicate that MR can both effectively monitor the cryosurgical freezing and thawing cycle and characterize the postcryosurgical changes in tissue during follow-up.

Synthesis and evaluation of high affinity, aryl-substituted [18F]fluoropropylbenzamides for dopamine D-2 receptor studies

The potent dopamine D-2 ligands (S)-2,3-dimethoxy-N-[(1-ethyl-2-pyrrolidinyl)methyl]-5(3- [18F]fluoropropyl)benzamide (18F-1) and (S)-2,3-dimethoxy-N-[(1-ethyl-2-pyrrolidinyl)methyl]-5-(3- [18F]fluoropropyl)-6-hydroxybenzamide (18F-2) were prepared in high specific activity and 5-25% overall radiochemical yields. Benzamide 1 possessed a lower in vitro binding affinity for the D-2 receptor than salicylamide 2, but the in vivo striatal-to-cerebellar radioactivity concentration ratios (St/Cb) in rats and dogs were nearly identical for the two compounds. Compound 18F-2 was more lipophilic than 18F-1, and its increased penetration into and retention by striatal tissue was matched by an increase in non-specific binding in the cerebellum. Cerebral cortex radioactivity concentration levels in dogs were similar to cerebellum levels. The binding of 18F-labelled 1 and 2 displayed regional brain distribution patterns consistent with known dopamine D-2 receptor densities and was selectively blocked in the striatum of rats by dopamine D-2 antagonists. The binding of 18F-1 was found to be stereoselective, as the 18F-labelled (R)-enantiomer displayed no selective retention in the striatum of dogs. High levels of radioactivity were found in the bones of rats following the injection of 18F-1 and 18F-2, indicating that in vivo defluorination had occurred; however, no bone radioactivity was observed in dogs following the injection of these radioligands. Compound 18F-1 was displaced from the striatum of dogs by both d-amphetamine-stimulated dopamine release and haloperidol at doses of 1 and 0.5 mg/kg, respectively, while compound 18F-2 was displaced from the dog striatum only by haloperidol at these doses. The radioligand 18F-2 holds promise for positron emission tomography studies of the dopamine D-2 receptor system based upon its selective, potent binding and resistance to displacement by endogenous dopamine.

MRI and PET of delayed heavy-ion radiation injury in the rabbit brain

Magnetic resonance imaging (MRI) and positron emission tomography (PET) techniques were used to obtain in vivo scans of delayed (30 GyE helium ion, 230 MeV/u) radiation injury in rabbit brain. T2-weighted (T2W) MRI scans demonstrated alterations that were restricted primarily to the white matter tracts and the deep perithalamic and thalamic regions. Quantitative measurements of T2 and T1 values demonstrated wide variations in absolute values. However, paired comparisons in hemibrain-irradiated rabbits revealed significant increases in T2 (p less than 0.001) and T1 (p less than 0.01) in irradiated versus unirradiated brain. Gadolinium DTPA (GdDTPA) enhanced MRI and 82Rubidium (82Rb) PET detected focal regions of blood-brain barrier (BBB) disruption restricted to the deep white matter and thalamic regions. Sequential GdDTPA enhanced MRI scans showed the spreading of the tracer from the initial site of contrast enhancement. 18Fluorodeoxyglucose (18FDG) PET studies demonstrated the markedly depressed metabolic profiles of irradiated brain. Histological findings of tissue edema and necrosis correlated well with the in vivo imaging abnormalities. These initial studies demonstrate that the irradiated rabbit brain is a suitable animal model for examining the delayed effects of radiation injury in the brain.

Cerebrovascular and metabolic perturbations in delayed heavy charged particle radiation injury

Focal heavy charged particle irradiation of the rabbit brain created defined lesions which were observable by nuclear magnetic resonance (NMR) and positron emission tomography (PET) imaging techniques. The lesions appeared approximately 9-11 months after left partial hemibrain irradiation with 30 Gy (230 MeV/u helium ions), and were restricted to the white matter tracts and deep perithalamic and thalamic regions. 82Rubidium PET and Gadolinium DTPA enhanced NMR imaging were used to detect blood-brain barrier perturbations. 18Fluordeoxyglucose PET studies demonstrated widespread decreases in cerebral glucose uptake in the cortex and thalamus of the irradiated hemisphere. NMR and PET imaging results correlated well with histological findings. Rabbits irradiated with 15 Gy did not demonstrate any abnormalities in the brain with sequential NMR scans through 14 months post-irradiation.

Synthesis and in vivo evaluation of 122I- and 131I-labelled iodoperidol, a potential agent for the tomographic assessment of cerebral perfusion

Iodoperidol (IP), an iodinated analogue of the antipsychotic drug haloperiodol, was evaluated as a cerebral blood flow radiopharmaceutical for PET or SPECT. IP was labelled with 131I or 122I (76% beta +, t1/2 = 3.6 min) in greater than 75% radiochemical yield via electrophilic aromatic iododestannylation. [131I]IP showed high cerebral uptake (1.9% of injected dose after 5 min) and good brain retention for the rat, with very low blood levels (brain/blood ratio = 35 at 2 h post injection). PET imaging of a dog demonstrated that [122I]IP has high selectivity for brain localization and good retention, and indicates that this class of compounds holds promise for development as perfusion radiopharmaceuticals.

Gallium-68 lipophilic complexes for labeling platelets

Generator produced 68Ga-labeled platelets could be useful for positron emission tomographic (PET) studies of thrombosis or atherosclerosis. To label platelets with 68Ga, we have studied the effects of trace metals in elutions of 68Ga from 68Ge. Studies were conducted on the formation of lipophilic 68Ga complexes 8-hydroxyquinoline, tropolone, and mercaptopyridine-N-oxide (MPO). Parameters such as pH, buffers, concentration of ligand, and stability with time were investigated. High performance liquid chromatography and instant thin layer chromatography were used to quantitate formation of the 68Ga complex. Platelets from human, dog, and rabbit plasma were incubated with the 68Ga complexes and the percent labeling determined. Accumulation of platelets in the catheter scraped aorta of the rabbit was determined by PET imaging, tissue counting, and autoradiography. Gallium-68 MPO gave 40-60% labeling of rabbit platelets with higher accumulation in the scraped aorta compared to the normal.