Partial volume correction incorporating Rb-82 positron range for quantitative myocardial perfusion PET based on systolic-diastolic activity ratios and phantom measurements.

BACKGROUND: Quantitative myocardial PET perfusion imaging requires partial volume corrections. METHODS: Patients underwent ECG-gated, rest-dipyridamole, myocardial perfusion PET using Rb-82 decay corrected in Bq/cc for diastolic, systolic, and combined whole cycle ungated images. Diastolic partial volume correction relative to systole was determined from the systolic/diastolic activity ratio, systolic partial volume correction from phantom dimensions comparable to systolic LV wall thicknesses and whole heart cycle partial volume correction for ungated images from fractional systolic-diastolic duration for systolic and diastolic partial volume corrections. RESULTS: For 264 PET perfusion images from 159 patients (105 rest-stress image pairs, 54 individual rest or stress images), average resting diastolic partial volume correction relative to systole was 1.14 ± 0.04, independent of heart rate and within ±1.8% of stress images (1.16 ± 0.04). Diastolic partial volume corrections combined with those for phantom dimensions comparable to systolic LV wall thickness gave an average whole heart cycle partial volume correction for ungated images of 1.23 for Rb-82 compared to 1.14 if positron range were negligible as for F-18. CONCLUSION: Quantitative myocardial PET perfusion imaging requires partial volume correction, herein demonstrated clinically from systolic/diastolic absolute activity ratios combined with phantom data accounting for Rb-82 positron range.

Interplay between temperature, fish partial migration and trophic dynamics

Whereas many studies have addressed the mechanisms driving partial migration, few have focused on the consequences of partial migration on trophic dynamics, and integrated studies combining the two approaches are virtually nonexistent. Here we show that temperature affects seasonal partial migration of cyprinid fish from lakes to predation refuges in streams during winter and that this migration in combination with temperature affects the characteristics and phenology of lower trophic levels in the lake ecosystem. Specifically, our six-year study showed that the proportion of fish migrating was positively related to lake temperature during the pre-migration growth period, i.e. during summer. Migration from the lake occurred later when autumn water temperatures were high, and timing of return migration to the lake occurred earlier at higher spring water temperatures. Moreover, the winter mean size of zooplankton in the lake increased with the proportion of fish being away from the lake, likely as a consequence of decreased predation pressure. Peak biomass of phytoplankton in spring occurred earlier at higher spring water temperatures and with less fish being away from the lake. Accordingly, peak zooplankton biomass occurred earlier at higher spring water temperature, but relatively later if less fish were away from the lake. Hence, the time between phyto- and zooplankton peaks depended only on the amount of fish being away from the lake, and not on temperature. The intensity of fish migration thereby had a major effect on plankton spring dynamics. These results significantly contribute to our understanding of the interplay between partial migration and trophic dynamics, and suggest that ongoing climate change may significantly affect such dynamics.

$\beta\sb2$-adrenergic receptor desensitization, internalization and phosphorylation in response to full and partial agonists

The objective of this study is to test the hypothesis that partial agonists produce less desensitization because they generate less of the active conformation of the $\beta\sb2$-adrenergic receptor ($\beta$AR) (R*) and in turn cause less $\beta$AR phosphorylation by beta adrenergic receptor kinase ($\beta$ARK) and less $\beta$AR internalization. In the present work, rates of desensitization, internalization, and phosphorylation caused by a series of $\beta$AR agonists were correlated with a quantitative measure, defined as coupling efficiency, of agonist-dependent $\beta$AR activation of adenylyl cyclase. These studies were preformed in HEK-293 cells overexpressing the $\beta$AR with hemagglutinin (HA) and 6-histidine (6HIS) epitopes introduced into the N- and C-termini respectively. Agonists chosen provided a 95-fold range of coupling efficiencies, and, relative to epinephrine, the best agonist, (100%) were fenoterol (42%), albuterol (4.9%), dobutamine (2.5%) and ephedrine (1.1%). At concentrations of these agonists yielding $>$90% receptor occupancy, the rate and extent of the rapid phase (0-30 min) of agonist induced desensitization of adenylyl cyclase followed the same order as coupling efficiency, that is, epinephrine $\ge$ fitnoterol $>$ albuterol $>$ dobutamine $>$ ephedrine. The rate of internalization, measured by a loss of surface receptors during desensitization, with respect to these agonists also followed the same order as the desensitization and exhibited a slight lag. Like desensitization and internalization, $\beta$AR phosphorylation exhibited a dependency on agonist strength. The two strongest agonists epinephrine and fenoterol provoked 11 to 13 fold increases in the level of $\beta$AR phosphorylation after just 1 min, whereas the weakest agonists dobutamine and ephedrine caused only 3 to 4 fold increases in phosphorylation. With longer treatment times, the level of $\beta$AR phosphorylation declined with the strong agonists, but progressively increased with the weaker partial agonists. The major conclusion drawn from this study is that the occupancy-dependent rate of receptor phosphorylation increases with agonist coupling efficiencies and that this is sufficient to explain the desensitization, internalization, and phosphorylation data obtained.^ The mechanism of activation and desensitization by the partial $\beta$AR agonist salmeterol was also examined in this study. This drug is extremely hydrophobic and its study presents possibly unique problems. To determine whether salmeterol induces desensitization of the $\beta$AR its action has been studied using our system. Employing the use of reversible antagonists it was found that salmeterol, which has an estimated coupling efficiency near that of albuterol caused $\beta$AR desensitization. This desensitization was much reduced relative to epinephrine. Consistent with its coupling efficiency, it was found to be similar to albuterol in its ability to induce internalization and phosphorylation of the $\beta$AR. (Abstract shortened by UMI.) ^

A nonparametric method of comparing the partial areas under two correlated receiver operating characteristic curves

A non-parametric method was developed and tested to compare the partial areas under two correlated Receiver Operating Characteristic curves. Based on the theory of generalized U-statistics the mathematical formulas have been derived for computing ROC area, and the variance and covariance between the portions of two ROC curves. A practical SAS application also has been developed to facilitate the calculations. The accuracy of the non-parametric method was evaluated by comparing it to other methods. By applying our method to the data from a published ROC analysis of CT image, our results are very close to theirs. A hypothetical example was used to demonstrate the effects of two crossed ROC curves. The two ROC areas are the same. However each portion of the area between two ROC curves were found to be significantly different by the partial ROC curve analysis. For computation of ROC curves with large scales, such as a logistic regression model, we applied our method to the breast cancer study with Medicare claims data. It yielded the same ROC area computation as the SAS Logistic procedure. Our method also provides an alternative to the global summary of ROC area comparison by directly comparing the true-positive rates for two regression models and by determining the range of false-positive values where the models differ. ^

Apoptosis of ligamentous cells of the cranial cruciate ligament from stable stifle joints of dogs with partial cranial cruciate ligament rupture

OBJECTIVE To describe the presence and amount of apoptotic ligamentous cells in different areas of partially ruptured canine cranial cruciate ligaments (prCCLs) and to compare these findings with apoptosis of ligamentous cells in totally ruptured cranial cruciate ligaments (trCCLs). ANIMALS 20 dogs with prCCLs and 14 dogs with trCCLs. PROCEDURES Dogs with prCCLs or trCCLs were admitted to the veterinary hospital for stifle joint treatment. Biopsy specimens of the intact area of prCCLs (group A) and the ruptured area of prCCLs (group B) as well as specimens from trCCLs (group C) were harvested during arthroscopy. Caspase-3 and poly (ADP-ribose) polymerase (PARP) detection were used to detect apoptotic ligamentous cells by immunohistochemistry. RESULTS No difference was found in the degree of synovitis or osteophytosis between prCCLs and trCCLs. No difference was found in degenerative changes in ligaments between groups A and B. A substantial amount of apoptotic cells could be found in > 90% of all stained slides. A correlation (r(s) = 0.71) was found between the number of caspase-3-and PARP-positive cells. No significant difference was found in the amount of apoptotic cells among the 3 groups. No significant correlation could be detected between the degree of synovitis and apoptotic cells or osteophyte production and apoptotic cells. CONCLUSIONS AND CLINICAL RELEVANCE The lack of difference between the 3 groups indicates that apoptosis could be a factor in the internal disease process leading to CCL rupture and is not primarily a consequence of the acute rupture of the ligament.

Neurologic outcome after thoracolumbar partial lateral corpectomy for intervertebral disc disease in 72 dogs

OBJECTIVE To determine neurologic outcome and factors influencing outcome after thoracolumbar partial lateral corpectomy (PLC) in dogs with intervertebral disc disease (IVDD) causing ventral spinal cord compression. STUDY DESIGN Retrospective case series. ANIMALS Dogs with IVDD (n = 72; 87 PLC). METHODS Dogs with IVDD between T9 and L5 were included if treated by at least 1 PLC. Exclusion criteria were: previous spinal surgery, combination of PLC with another surgical procedure. Neurologic outcome was assessed by: (1) modified Frankel score (MFS) based on neurologic examinations at 4 time points (before surgery, immediately after PLC, at discharge and 4 weeks after PLC); and (2) owner questionnaire. The association of the following factors with neurologic outcome was analyzed: age, body weight, duration of current neurologic dysfunction (acute, chronic), IVDD localization, breed (chondrodystrophic, nonchondrodystrophic), number of PLCs, degree of presurgical spinal cord compression and postsurgical decompression, slot depth, presurgical MFS. Presurgical spinal cord compression was determined by CT myelography (71 dogs) or MRI (1 dog), whereas postsurgical decompression and slot depth were determined on CT myelography (69 dogs). RESULTS MFS was improved in 18.7%, 31.7%, and 64.2% of dogs at the 3 postsurgical assessments, whereas it was unchanged in 62.6%, 52.8%, and 32.0% at corresponding time points. Based on owner questionnaire, 91.4% of dogs were ambulatory 6 months postsurgically with 74.5% having a normal gait. Most improvement in neurologic function developed within 6 months after surgery. Presurgical MFS was the only variable significantly associated with several neurologic outcome measurements (P < .01). CONCLUSIONS PLC is an option for decompression in ventrally compressing thoracolumbar IVDD. Prognosis is associated with presurgical neurologic condition.

Perineal incision into the corpus spongiosum penis to resolve persistent post urination haemorrhage after partial phallectomy

Partial phallectomy or en bloc resection are surgical methods to address pathological conditions of the penis and/or prepuce including neoplasia, trauma, habronemiasis, chronic paraphimosis or permanent penile paralysis, and priapism. Haemorrhage associated with urination is a common complication observed after penile surgery but usually resolves spontaneously without specific treatment. This report describes a case of post urination haemorrhage (PUH) that recurred with each urination and persisted without significant improvement for a period of 2 weeks following en bloc resection of the penis and the prepuce. A perineal incision (PI) into the corpus spongiosum of the penis (CSP) resolved PUH by decreasing the blood pressure in the CSP distal to the PI. We propose that PI of the CSP can be an effective method to address PUH after penile surgery and may decrease time of hospitalisation for horses affected with PUH after phallectomy procedures.

Cloning, sequencing and partial functional characterization of the 5' region of the human p75 tumor necrosis factor receptor-encoding gene (TNF-R)

A 1887-bp region at the 5' flank of the human p75 tumor necrosis factor receptor (p75 TNF-R)-encoding gene was found to be active in driving expression of the luc (luciferase-encoding) reporter gene, suggesting that it contains the promoter for the receptor. Rather unexpectedly, a 1827-bp region at the 3' end of the first intron of the p75 TNF-R gene also displayed promoter activity. This activity may be artefactual, reflecting only the presence of an enhancer in this region; yet it also raises the possibility that p75 TNF-R is controlled by more than one promoter and that it encodes various forms of the receptor, or even other proteins. We present here the nucleotide sequences of the 5' flanking and intron regions. Possible implications for the transcriptional regulation of the p75 TNF-R gene are discussed.

Elevated liver regeneration in response to pharmacological reduction of elevated portal venous pressure by terlipressin after partial hepatectomy.

BACKGROUND Liver regeneration is of crucial importance for patients undergoing living liver transplantations or extended liver resections and can be associated with elevated portal venous pressure, impaired hepatic regeneration, and postoperative morbidity. The aim of this study was to assess whether reduction of portal venous pressure by terlipressin improves postoperative liver regeneration in normal and steatotic livers after partial hepatectomy in a rodent model. METHODS Portal venous pressure was assessed after minor (30%), standard (60%), or extended (80%) partial hepatectomy (PH) in mice with and without liver steatosis. Liver regeneration was assessed by BrdU incorporation and Ki-67 immunostaining. RESULTS Portal venous pressure was significantly elevated post-PH in mice with normal and steatotic livers compared to sham-operated mice. Reduction of elevated portal pressure after 80% PH by terlipressin was associated with an increase of hepatocellular proliferation. In steatotic livers, animals treated with terlipressin had an increase in liver regeneration after 30% PH and increased survival after 60% PH. Mechanistically, terlipressin alleviated IL-6 mRNA expression following PH and down-regulated p21 and GADD45 mRNA suggesting a reduction of cell cycle inhibition and cellular stress. CONCLUSIONS Reduction of elevated portal pressure post-PH by the use of terlipressin improves liver regeneration after PH in lean and steatotic mouse livers.

Fully Adaptive Newton--Galerkin Methods for Semilinear Elliptic Partial Differential Equations

In this paper we develop an adaptive procedure for the numerical solution of general, semilinear elliptic problems with possible singular perturbations. Our approach combines both prediction-type adaptive Newton methods and a linear adaptive finite element discretization (based on a robust a posteriori error analysis), thereby leading to a fully adaptive Newton–Galerkin scheme. Numerical experiments underline the robustness and reliability of the proposed approach for various examples