[Diagnostic performance of bone scintigraphy and (11)C-Choline PET/CT in the detection of bone metastases in patients with biochemical recurrence of prostate cancer]

AIM

To compare bone scan (BS) with (11)C-Choline PET/CT for the detection of bone metastases in patients with biochemical recurrence of prostate cancer (PC).

MATERIAL AND METHODS

A total of 169 patients with biochemical recurrence of PC(PSA:2.4-58 ng/ml) who were referred for both exams (0-15 days-in-between) were included. Lesion-detection-rate per patients and lesions were analyzed for both BS and (11)C-Choline PET/CT. Metastasis diagnosis was reached by: biopsy, CT/(18)F-Fluoride PET/MRI confirmation, or evidence of progression in subsequent imaging procedures.

RESULTS

A total of 91 lesions were found to be active in BS and/or (11)C-choline PET/CT (40 patients), with 78 of which were metastatic. BS detected 38 blastic, 2 lytic and 10 non-CT-evident lesions. (11)C-Choline PET/CT detected 41 blastic, 4 lytic and 29 non-CT-evident lesions. BS and (11)C-Choline PET/CT sensitivities were 65.4% and 96.1%; specificities ere 38.5 and 92.3% (χ(2) 8.27, p<0.04). Both imaging techniques were negative in 118 patients. Tracer avid lesions were found in 51 patients: with 30/51 being BS and (11)C-Choline PET/CT concordant; in 21/51 patients had discordant lesions (kappa 0.712, p=0.00). Lesions were absolutely discordant in 10/19 patients,: 5 FN BS, 2 FP BS (degenerative changes; dysplasia), 1 FN (11)C-Choline PET/CT (blastic), 1 FP (11)C-Choline PET/CT (degenerative), 1 out of field-of-view lesion with (11)C-Choline PET/CT (tibia alone). (11)C-Choline PET/CT showed extraosseous involvement in 26/51 patients with bone metastases: 9 local recurrences, 5 infra-diaphragmatic-lymph-nodes, 2 supra-diaphragmatic, 5 local and infra-diaphragmatic, 4 infra- and supra-diaphragmatic, 1 supra-diaphragmatic and lung metastases.

CONCLUSION

(11)C-Choline PET/CT yielded better sensitivity and specificity than BS for the detection of bone involvement in patients with biochemical recurrence of PC and allowed extraosseous restaging, with an impact in the clinical management of these patients.

Partner associations across sympatric broad-headed bug species and their environmentally acquired bacterial symbionts

Many organisms have intimate associations with beneficial microbes acquired from the environment. These host-symbiont associations can be specific and stable, but they are prone to lower partner specificity and more partner-switching than vertically transmitted mutualisms. To investigate partner specificity in an environmentally acquired insect symbiosis, we used 16S rRNA gene and multilocus sequencing to survey the bacterial population in the bacteria-harbouring organ (crypts) of 49 individuals across four sympatric broad-headed bug species (Alydus calcaratus, A. conspersus, A. tomentosus and Megalotomus quinquespinosus). Similar to other insect-bacteria associations, Burkholderia spp. were the most common residents of the crypts in all four insect species (77.2% of recovered sequences). Burkholderia presence was associated with prolonged survival to adulthood in A. tomentosus, suggesting a beneficial role of these specialized associations. Burkholderia were also found in environmental reservoirs in the insects' habitat, which may facilitate acquisition by insects by increasing Burkholderia-insect encounters. Symbiont establishment could also be facilitated by resistance to insect defences; zone of inhibition assays demonstrated that Burkholderia and other bacteria isolated from crypts are resistant to insect defences that limit growth of Escherichia coli. Alternatively, the insects' defences may not efficiently kill a broad range of bacteria. Although the symbiosis is targeted to Burkholderia, the insects' crypts housed other bacteria, including non-Burkholderiaceae species. There is no significant effect of host insect species on Burkholderia distribution, suggesting a lack of strong partner specificity at finer scales. The presence of frequent partner-switching between sympatric insects and their symbionts likely prevents tight co-evolutionary dynamics.

An analysis of geothermal and carbonic springs in the western United States sustained by deep fluid inputs

Hydrothermal springs harbor unique microbial communities that have provided insight into the early evolution of life, expanded known microbial diversity, and documented a deep Earth biosphere. Mesothermal (cool but above ambient temperature) continental springs, however, have largely been ignored although they may also harbor unique populations of micro-organisms influenced by deep subsurface fluid mixing with near surface fluids. We investigated the microbial communities of 28 mesothermal springs in diverse geologic provinces of the western United States that demonstrate differential mixing of deeply and shallowly circulated water. Culture-independent analysis of the communities yielded 1966 bacterial and 283 archaeal 16S rRNA gene sequences. The springs harbored diverse taxa and shared few operational taxonomic units (OTUs) across sites. The Proteobacteria phylum accounted for most of the dataset (81.2% of all 16S rRNA genes), with 31 other phyla/candidate divisions comprising the remainder. A small percentage (~6%) of bacterial 16S rRNA genes could not be classified at the phylum level, but were mostly distributed in those springs with greatest inputs of deeply sourced fluids. Archaeal diversity was limited to only four springs and was primarily composed of well-characterized Thaumarchaeota. Geochemistry across the dataset was varied, but statistical analyses suggested that greater input of deeply sourced fluids was correlated with community structure. Those with lesser input contained genera typical of surficial waters, while some of the springs with greater input may contain putatively chemolithotrophic communities. The results reported here expand our understanding of microbial diversity of continental geothermal systems and suggest that these communities are influenced by the geochemical and hydrologic characteristics arising from deeply sourced (mantle-derived) fluid mixing. The springs and communities we report here provide evidence for opportunities to understand new dimensions of continental geobiological processes where warm, highly reduced fluids are mixing with more oxidized surficial waters.

[Detection of tumors in the central zone of the prostate with 11C-Choline PET/CT]

Prostate tumors originate 68% in the peripheral region and 24% in the transitional region where tumors originating in the central zone are rare (8%). However, diagnosis of the tumors in the central zone is important since they exhibit greater aggressiveness conditioned by their location and different biological behavior. Magnetic resonance imaging shows problems in identifying lesions in the central prostate zone, since this region has a heterogeneous signal, mainly after the primary treatment. Ultrasound guided sextant biopsy shows a negative result in 28% of prostate tumors. Therefore, it is advisable to repeat or even to perform saturation biopsies. We present two patients, one of them with suspected biochemical prostate cancer and one with biochemical recurrence after radical treatment. In both, (11)C-Choline PET/CT allowed detection of the tumor focus in the central zone of the prostate, with negative complementary diagnostic test and biopsies.

[Incidence of focal myocardial (18)F-FDG uptake and correlation with coronary calcifications by PET/CT]

OBJECTIVE

To evaluate the incidence of (18)F-FDG focal uptake in the myocardium as well as its correlation with coronary vessel calcifications.

MATERIAL AND METHODS

A total of 130 patients who underwent an oncological PET/CT study were reviewed retrospectively. Sixty-five had undergone a myocardial perfusion study because of clinical suspicion of coronary artery disease (group 1). There were no significant differences in age and gender regarding another group of the same series (n=65; group 2). Focal myocardial (18)F-FDG uptake and the presence of coronary vessel calcifications were identified by 2 independent observers.

RESULTS

Group 1: in 18 out of 65 patients (28%) focal myocardial (18)F-FDG uptake was identified (5 had 2 foci; total: 23 foci). In 43 out of 65 studies (66%), calcification was identified in the coronary vessels. Group 2: in 6 out of 65 patients (9%) focal myocardial (18)F-FDG uptake was identified (1 had 2 foci; total: 7 foci). In 17 out of 65 studies (26%), calcification was identified in the coronary vessels. Comparative analysis: focal myocardial (18)F-FDG uptake and coronary vessel calcifications were more frequent in the group 1 patients (p<0.01). There was no correlation between the presence of coronary vessel calcifications and focal myocardial (18)F-FDG uptake in individual patients in both groups (group 1: p=0.7; group 2: p=0.163).

CONCLUSIONS

PET/CT allows simultaneous assessment of focal myocardial (18)F-FDG uptake and myocardial vessel calcifications. Patients with clinical suspicion of coronary artery disease have a higher incidence of focal myocardial (18)F-FDG uptake and coronary calcifications. However, (18)F-FDG focal uptake is often observed in sites remote from those with calcification.

Corneal disease in patients with chronic renal insufficiency undergoing hemodialysis

PURPOSE

To evaluate alterations of the corneal endothelium in patients undergoing hemodialysis for renal insufficiency.

METHODS

Sixty-six patients undergoing hemodialysis received a complete ophthalmologic examination. The state of the endothelium was assessed using pachymetry and specular microscopy. The group of patients undergoing dialysis was divided according to the time of dialysis, aluminum, product of calcium and phosphate in blood, and parathyroid hormone to analyze the influence of these factors. The possible presence of iron and aluminum in the aqueous humor of patients who underwent and those who did not undergo hemodialysis was also estimated.

RESULTS

Patients undergoing hemodialysis did not have significant corneal edema. Cell density was significantly lower in patients undergoing dialysis than in patients not undergoing dialysis; this reduction appeared to be associated with length of dialysis and was unrelated to serum aluminum and calcium levels. Patients undergoing dialysis did not have cell polymorphism or polymegethism, although there was a tendency toward increased polymegethism with length of dialysis. Aluminum and iron were not increased in the aqueous humor of patients undergoing dialysis.

CONCLUSIONS

The alteration of the endothelium that we found is not related to the elements studied. It is possibly the result of another product dissolved in the anterior chamber or to the alterations of the anterior segment that these patients are known to have.

Macrophages transfer [14C]-labelled fatty acids to pancreatic islets in culture

Macrophages are able to produce, export, and transfer fatty acids to lymphocytes in culture. The purpose of this study was to examine if labelled fatty acids could be transferred from macrophages to pancreatic islets in co-culture. We found that after 3 h of co-culture the transfer of fatty acids to pancreatic islets was: arachidonic >> oleic > linoleic = palmitic. Substantial amounts of the transferred fatty acids were found in the phospholipid fraction; 87.6% for arachidonic, 59.9% for oleic, 53.1% for palmitic, and 36.9% for linoleic acids. The remaining radioactivity was distributed among the other lipid fractions analysed (namely polar lipids, cholesterol, fatty acids, triacylglycerol and cholesterol ester), varying with the fatty acid used. For linoleic acid, a significant proportion (63.1%) was almost equally distributed in these lipid fractions. Also, it was observed that transfer of fatty acids from macrophages to pancreatic islets is time-dependent up to 24 h, being constant and linear with time for palmitic acid and remaining constant after 12 h for oleic acid. These results lead us to postulate that in addition to the serum, circulating monocytes may also be a source of fatty acids to pancreatic islets, mainly arachidonic acid.

Value of SPECT imaging of the thoracolumbar spine in cancer patients

The purpose of this study was to evaluate the usefulness of SPECT bone imaging in targeting the precise location of vertebral abnormalities to ascertain whether such knowledge would help in differentiating between metastatic and benign lesions. SPECT images of the thoracolumbar spine in 50 patients were correlated with plain x-rays, CT, MRI, PET, and bone scans and 6-month clinical follow-ups. SPECT images revealed 110 lesions, 35 of which were metastases. Twenty-four of 25 lesions involving the vertebral body with extension into posterior elements were metastases, as well as 10 of 39 lesions found in the vertebral body and 1 of 4 found in the spinous process. All lesions limited to the anterior aspect of the vertebral body (13/13), facet joints (23/23), and intervertebral disk space (6/6) were benign. In conclusion, SPECT imaging of the thoracolumbar spine is helpful in determining the precise anatomic location of vertebral abnormalities, and knowledge of the location can be used to determine whether these abnormalities in cancer patients are benign entities or metastases.

Protein reverse staining: high-efficiency microanalysis of unmodified proteins detected on electrophoresis gels

A methodology is presented for efficiently gaining structural information from electrophoresed proteins after on-gel detection by imidazole-sodium dodecyl sulfate-zinc reverse staining. As a consequence of reverse staining, (a) protein bands arise transparent against a deep white-stained background, limits of detection being in the femtomole range; (b) there is no loss of image when the gel is kept in distilled water (even during years); and (c) protein bands result immobilized, i.e., they do not diffuse upon gel storage. To recover reverse-stained proteins or fragments thereof from the gel, the immobilization of bands must first be abrogated by chelating the zinc ions from stain (protein mobilization). We had originally described mobilization at low pH by using citric acid. Here, we improve this procedure regarding the protein electrotransfer. We demonstrate that mobilization is efficiently done at neutral to alkaline pH by short-term (5 to 10 min) incubation of the gel in a buffer containing glycine or dithiothreitol prior to transfer. Moreover, mobilization was most simply performed by just adding the zinc chelating agent to the transfer buffer. Reverse staining and the new mobilization procedure made electrotransferring single protein bands from gel onto small-sized (13 x 5 mm2) PVDF membrane pieces in mini sandwich-like assemblies practical. Equipment is described for the protein electroblotting in such minisandwiches. Microsequence analysis of the electroblotted proteins showed initial yields in the range of those achieved when the transfer was done from unstained control gels. Protein bands kept in the reverse-stained gel for prolonged time periods (even for as long as 2 years) could be similarly analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

The impact of HLA mismatches on the survival of first cadaveric kidney transplants

BACKGROUND

The benefits of HLA-A, B, and DR matching of cadaveric kidney grafts and recipients remain controversial when viewed from the perspective of social equity and graft survival.

METHODS

We estimated graft survival using proportional-hazards techniques, adjusting for patient and donor characteristics, for a series of 30,564 Medicare patients receiving a first cadaveric kidney transplant between 1984 and 1990. The effects of minimal achievable HLA mismatches and maximal matching on graft survival were estimated by simulated allocation of a sample of organs to a sample of 20,000 candidates for transplantation.

RESULTS

The adjusted one-year graft survival was 84.3 percent for grafts with no mismatches and 77.0 percent for grafts with four mismatches. National rationing of donor organs to achieve minimal mismatching and maximal matching could potentially decrease the average number of HLA mismatches from 3.6 to 1.2, with a corresponding increase in the number of matches. As a consequence, projected five-year graft survival could potentially increase from 58.5 percent to 62.9 percent. This would be associated with a decrease in the proportion of kidneys allocated to black recipients from 22.2 to 15.0 percent.

CONCLUSIONS

Under ideal circumstances, a policy of maximal matching of cadaveric renal transplants would increase five-year graft survival by a comparatively small 4.4 percentage points, but the actual benefit is likely to be smaller.

Direct blotting, sequencing and immunodetection of proteins after five-minute staining of SDS and SDS-treated IEF gels with Nile red

The non-covalent dye Nile red allows the fast and simple fluorescent staining of protein bands in sodium dodecyl sulfate (SDS)-polyacrylamide gels. This procedure has been extended to polyacrylamide isoelectric focusing gels that do not contain SDS. Unlike the current methods using Coomassie blue or silver for gel staining, Nile red staining does not preclude the direct electroblotting of protein bands onto polyvinylidene difluoride membranes, and the transferred proteins can be used directly for immunoblotting analysis and for N-terminal microsequencing.