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A novel β-carotene hydroxylase catalyzes the formation of rhodoxanthin, an unusual carotenoid in red honeysuckle berries., Rhodoxanthin is a vibrant red carotenoid found across the plant kingdom and in certain birds and fish. It is a member of the atypical retro class of carotenoids, which contain an additional double bond and a concerted shift of the conjugated double bonds relative to the more widely occurring carotenoid pigments, and whose biosynthetic origins have long remained elusive. Here, we identify LHRS (Lonicera hydroxylase rhodoxanthin synthase), a variant β-carotene hydroxylase (BCH)–type integral membrane diiron enzyme that mediates the conversion of β-carotene into rhodoxanthin. We identify residues that are critical to rhodoxanthin formation by LHRS. Substitution of only three residues converts a typical BCH into a multifunctional enzyme that mediates a multistep pathway from β-carotene to rhodoxanthin via a series of distinct oxidation steps in which the product of each step becomes the substrate for the next catalytic cycle. We propose a biosynthetic pathway from β-carotene to rhodoxanthin.

Imaging and therapy using radiolabelled somatostatin analogues are methods successfully used in patients with somatostatin receptor (SSTR)-expressing neuroendocrine tumours. Since these techniques were first introduced, many improvements have been made. SSTR expression has also been reported on breast cancer (BC). Currently mammography, magnetic resonance imaging and ultrasound are the most frequent methods used for BC imaging. Since SSTR expression on BC was demonstrated, clinical studies examining the feasibility of visualizing primary BC using SSTR radioligands have been performed. However, to date SSTR-mediated nuclear imaging is not used clinically in BC patients. The aim of this review is to assess whether recent improvements made within nuclear medicine may enable SSTR-mediated imaging to play a role in BC management. For this we critically analysed results of past studies and discussed the potential of the improvements made within nuclear medicine on SSTR-mediated nuclear imaging of BC. Seven databases were searched for publications on BC imaging with SSTR radioligands. The papers found were analysed by 3 individual observers to identify whether the studies met the pre-set inclusion criteria defined as studies in which nuclear imaging using radiolabelled SST analogues was performed in patients with breast lesions. Twenty-four papers were selected for this review including studies on SSTR-mediated nuclear imaging in BC, neuroendocrine BC and other breast lesions. The analysed studies were heterogeneous with respect to the imaging method, imaging protocol, patient groups and the radiolabelled SST analogues used. Despite the fact that the analysed studies were heterogeneous, sensitivity for primary BC ranged from 36-100%. In a subset of the studies LN lesions were visualized, but sensitivity was lower compared to that for primary tumours. A part of the studies included benign lesions and specificity ranged from 22-100%. Furthermore, false negatives and false positives were reported. In the majority of the studies scan outcome was not associated with BC subtype. (C) 2016 Elsevier Inc. All rights reserved.

Introduction: Factors determining the in vivo uptake of radiolabeled somatostatin analogs by neuroendocrine tumors are poorly known. The aim is to evaluate in vivo tumor perfusion and regulation of somatostatin receptors (sstr) following acute exposure to octreotide, in an animal model of neuroendocrine tumor. Methods: (H2O)-O-15 flow studies were performed in 8 CA20948 tumor-bearing rats and another 36 rats underwent three [Ga-68]-DOTA-Tyr(3)-octreotate imaging sessions at 24-h intervals. After baseline (Day 0) imaging, scanning was repeated on Day 1 after octreotide injection (175 mu g/kg), with a variable delay: no injection (controls, n=7), coinjection (n=6), and octreotide injection 20 min (n=7), 2 h (n=8) and 4 h (n=8) before imaging. Repeat images without octreotide was performed at Day 2 followed by sacrifice and tumor counting. Results: (H2O)-O-15 studies failed to measure quantitative tumor perfusion in this model. On Day 1, ratio of tumor uptake to Day 0 was 1.2 +/- 0.3 in controls; 0.6 +/- 0.2 in the coinjection group; 0.9 +/- 0.2, 1.1 +/- 0.1 and 1.2 +/- 0.2 in the other groups, respectively. Uptake in the coinjection group showed a statistically significant reduction of tumor uptake (P < .0001). All groups showed increased uptake on Day 2, without statistical differences between groups. In vivo tumor counts showed good correlation with ex vivo countings (R-2=0.946). Conclusion: Acute exposure to unlabeled octreotide in this neuroendocrine tumor model results in a rapid recycling or resynthesis of sstr. Positron emission tomography (PET) allowed to reliably assess quantitative uptake of [Ga-68]-DOTA-Tyr(3)-octreotate over time in the same animal, but failed in this model to measure tumor perfusion. (C) 2010 Elsevier Inc. All rights reserved.

Peptide receptor scintigraphy with the radioactive somatostatin analogue 111In-DTPA-octreotide is a sensitive and specific technique to show in vivo the presence of somatostatin receptors on various tumours. Since 111In emits not only gamma rays but also therapeutic Auger and internal conversion electrons with a medium to short tissue penetration (0.02-10 microm and 200-550 microm, respectively), 111In-DTPA-octreotide is also being used for peptide receptor radionuclide therapy (PRRT). In this study we investigated the therapeutic effects of 111In-DTPA-octreotide in tumours of various sizes. Regrowth of a tumour despite PRRT with 111In-DTPA-octreotide may be due to the lack of crossfire from 111In, whereby any possible receptor-negative tumour cell can multiply. We therefore also investigated the somatostatin receptor status of the tumour before and after PRRT.The radiotherapeutic effects of different doses of 111In-DTPA-octreotide in vivo were investigated in Lewis rats bearing small (or = 1 cm2) or large (or = 8 cm2) somatostatin receptor-positive rat pancreatic CA20948 tumours expressing the somatostatin receptor subtype 2 (sst2). In addition, the somatostatin receptor density on the tumour after injection of a therapeutic labelled somatostatin analogue was investigated when the tumour was either declining in size or regrowing after an initial reduction in size. To initiate a partial response of the tumour (so that regrowth would follow) and not a complete response, a relatively low dose was administered.Impressive radiotherapeutic effects of 111In-labelled octreotide were observed in this rat tumour model. Complete responses (up to 50%) were found in the animals bearing small (or 1 cm2) tumours after at least three injections of 111 MBq or a single injection of 370 MBq 111In-DTPA-octreotide, leading to a dose of 6.3-7.8 mGy/MBq (1-10 g tumour). In the rats bearing the larger (or = 8 cm2) tumours, the effects were much less pronounced and only partial responses were achieved in these groups. Clear sst2 expression was found in the control as well as in the treated tumours. A significantly higher tumour receptor density (p0.001) was found when the tumours regrew after an initial decline in size after low-dose PRRT in comparison with the untreated tumours.Therapy with 111In-labelled somatostatin analogues is feasible but should preferably start as early as possible during tumour development. One might also consider the use of radiolabelled somatostatin analogues in an adjuvant setting after surgery of somatostatin receptor-positive tumours in order to eradicate occult metastases. We showed that PRRT led to an increase in the density of somatostatin receptors when the tumours regrew after an initial decline in size because of PRRT. Upregulation of the somatostatin receptor may lead to higher uptake of radiolabelled peptides in therapeutic applications, which would probably make repeated injections of radiolabelled peptides more effective.

The rat pancreatic CA20948 tumor cell line is widely used in receptor-targeted preclinical studies because many different peptide receptors are expressed on the cell membrane. The response of the tumor cells to peptide radionuclide therapy, however, is dependent on the cell line's radiosensitivity. Therefore, we measured the radiosensitivity of the CA20948 tumor cells by using clonogenic survival assays after high-energy external-beam radiotherapy (XRT) in vitro. It can, however, be expected that results of high-dose-rate XRT are not representative for those after low-dose-rate radionuclide therapy (RT), such as peptide-receptor radionuclide therapy. Therefore, we compared clonogenic survival in vitro in CA20948 tumor cells after increasing doses of XRT or RT, the latter using (131)I.Survival of CA20948 cells was investigated using a clonogenic survival assay after RT by incubation with increasing amounts of (131)I, leading to doses of 1-10 Gy after 12 days of incubation (maximum dose rate, 0.92 mGy/min), or with doses of 1-10 Gy using an X-ray machine (dose rate, 0.66 Gy/min). Colonies were scored after a 12-day-incubation period. Also, the doubling time of this cell line was calculated.We observed a dose-dependent reduction in tumor-cell survival, which, at low doses, was similar for XRT and RT. For high-dose-rate XRT, the quadratic over linear component ratio (alpha/beta) for CA20948 was 8.3 Gy, whereas that ratio for low-dose-rate RT was calculated to be 86.5 Gy. The calculated doubling time of CA20948 cells was 22 hours.Despite the huge differences in dose rate, RT tumor cell-killing effects were approximately as effective as those of XRT at doses of 1 and 2 Gy, the latter being the common daily dose given in fractionated external-beam therapies. At higher doses, RT was less effective than XRT.

textabstractBACKGROUND: Coronary atherectomy provides a unique opportunity to obtain plaque tissue from a wide variety of clinical syndromes. We investigated the relation between the clinical status and histopathological substrate of tissue retrieved during directional coronary atherectomy and the proliferative and migratory potential of smooth-muscle cells judged from successful outgrowth during cell culture. METHODS: After directional coronary atherectomy, tissue samples were examined macroscopically, divided into two equal pieces, and separately subjected to cell culture and histopathological study. Cell culture was performed using an explant technique. In-vitro smooth-muscle cell outgrowth was related to clinical and histological variables. RESULTS: Atherosclerotic tissue was obtained from 98 consecutive atherectomy procedures. Histological examination revealed a broad spectrum of appearances, ranging from complex atheroma containing dense fibrous tissue, calcium deposits, macrophages, and necrotic debris to neointimal proliferation and organized thrombi. Smooth-muscle cell outgrowth was observed in 43 of the 98 samples (44%). Although not affected by any of the clinical variables, cell outgrowth was influenced by histological variables, in particular the presence of organizing thrombi. Outgrowth was successful in eight out of 10 samples with thrombus (80%) and in only 35 out of 88 (40%) without (P = 0.03). CONCLUSION: The presence of organizing thrombi in the retrieved tissue facilitates smooth-muscle cell outgrowth and suggests an enhanced proliferative and migratory potential. These findings may be relevant to the understanding of neointimal proliferation in coronary syndromes where mural thrombosis is likely to occur.

Unstable angina is an acute coronary syndrome associated with substantial short- and medium-term morbidity and mortality.1 The understanding of the pathogenesis of this syndrome has been based largely on postmortem studies of coronary arteries2 and supported by indirect evidence of coronary thrombosis in relation to the syndrome.3–5 Because directional coronary atherectomy is unique in extracting intact atheromatous tissue during coronary recanalization, it may facilitate the study of the processes taking place in the vessel in different coronary syndromes. In the present study the histopathologic characteristics of atherectomy samples retrieved in 93 patients with stable or unstable angina pectoris were compared and related to different clinical variables.

Z. Bardy GH, Troutman C, Johnson G, Mehra R, Poole JE, Dolack GE, Kudenchuk P J, Gartman DM. Electrode system influence on biphasic waveform defibrillation efficacy in h~urnax~s. Circulation 1991; 84:665-71. 2. Kavanagh KM, Tang ASL, Rollins DL, Smith WM, Ideker RE. Comparison of the internal defibrillation thresholds for monophasic and double and single capacitor biphasic waveforms. J Am Coll Cardiol 1989;14:1343-9. 3. Swartz JF, Fletcher RD, Karasik PE. Optimization of biphasic waveforms for human nonthoracotomy defibrillation. Circulation 1993; 88:2646-54. 4. Neuzner J, Pitschner HF, Huth C, Schlepper M. Effect of biphasic waveform pulse on endocardial defibrillation efficacy in humans. PACE 1994;17:207-12. 5. Block M, HammeI D, Bocker D, Borgreffe M, Budde T, Isbruch F, Wietholt D, Scheld HH, Breithardt G. A prospective randomized crossover comparison of monoand biphasic defibrillation using nonthoracotomy lead configurations in humans. J Cardiovasc Electrophysiol 1994;5:581-90. 6. Natale A, Deshpande S, Budziszewski M. Defibrillation threshoid with three different biphasic shapes incorporated in commercially available devices [Abstract]. Circulation 1994;90(part 2):I-499.

Objectives. The purpose of this study was to examine the proliferative capacity and extracellular matrix synthesis of human coronary plaque cells in vitro. Background. Common to both primary atherosclerosis and restenosis are vascular smooth muscle cell proliferation and production of extracellular matrix proteins. The applicability to humans of experimental animal models of these processes has been questioned. Methods. Primary atherosclerotic and restenotic lesions were excised by percutaneous directional coronary atherectomy in 93 patients. Smooth muscle cells were cultivated by an explant technique and identified by their morphology in culture, ultrastructural features under electron microscopy and immunostaining using monoclonal antibodies to smooth muscle cell alpha-actin. Proliferation in secondary culture was assessed with growth curves and the synthesis of collagen and sulfated glycosaminoglycans by the incorporation of 3H-proline and 35S-sulfate, respectively. These studies were also performed in cells derived from human umbilical artery media. Results. Success rates for primary (45%) and secondary (12%) culture of coronary cells were not influenced by clinical variables or lesion category. Primary culture success was improved by the presence of organized thrombus in the plaque and in relation to increased maximal cell density of the atherectomy specimen. Restenotic cells displayed more rapid growth than did cells of primary atherosclerotic origin, which grew in a manner similar to that of umbilical artery cells. Mean calculated population-doubling for the three cell groups were 52 h (95% confidence interval [CI] 48 to 58 h), 71 h (95% CI 62 to 83 h) and 74 h (95% CI 65 to 84 h), respectively. Restenotic and primary atherosclerotic cells did not differ in the synthesis of collagen ([mean ± SEM] 0.034 ± 0.004 vs. 0.033 ± 0.004 nmol isotope· μg protein−1, p = NS) or sulfated glycosaminoglycans (11.47 ± 1.07 vs. 15.37 ± 3.10 nmol isotope· μg protein−1, p = NS), but the coronary cells synthesized significantly more collagen and sulfated glycosaminoglycans than did umbilical artery cells (0.019 ± 0.004 and 5.43 ± 1.00 nmol isotope· μg protein−1, respectively, both p < 0.05). Conclusions. These data indicate that increased smooth muscle cell proliferation contributes to coronary restenosis in humans and support the concept that the extracellular matrix synthesis of adult smooth muscle cells is important to lesion formation.

The influence of mechanical stimulation by intermittent compressive force (ICF) of physiologic magnitude on osteoclastic bone resorption was investigated in cultures of fetal mouse cartilaginous long bones. Exposure to ICF resulted in a significant decrease in mineral resorption, as indicated by the decreased release of 45Ca and a decreased number of osteoclasts in the diaphysis. Conditioned medium (CM) from ICF-exposed periosteum-free cultures (ICF-CM), but not from control cultures (Co-CM), inhibited mineral resorption in fresh bones cultured under control conditions. Co-CM increased, but ICF-CM decreased, the number of tartrate-resistant acid phosphatase-positive cells in 7-day bone marrow cultures. Direct exposure of bone marrow cultures to ICF yielded the same results. Thus, osteoclastic bone resorption in cartilaginous long bones is inhibited by ICF in vitro. A soluble factor(s) acting on tartrate-resistant acid phosphatase-positive, osteoclast precursor-like cells seems to play a role in this effect.