Dendronized Porphyrins: Molecular Design and Synthesis

Abstract:

In this review, we report different methods and strategies to synthesize flexible and rigid dendronized porphyrins. We will focus on porphyrin dendrimers that have been reported in the last 10 years. Particularly, in our research group, we have designed and synthesized different series of dendronized porphyrins (free base and metallated) with pyrene units at the periphery and Fréchet-type dendritic arms. The Lindsey methodology has allowed the synthesis of meso-substituted porphyrins with various substitution patterns, such as symmetric, dissymmetric, or unsymmetric. Porphyrin dendrimers have been prepared by different synthetic methodologies; one of the most reported being the convergent method, where the dendrons are first prepared and further linked to a meso-substituted functionalized porphyrin unit, which will constitute the core of the dendrimer. Another interesting synthetic approach is the use of a reactive dendron bearing a terminal aldehyde functional group to form the final porphyrin core. In this way, a two-armed dendronized dissymmetric porphyrin core can be prepared from a dendritic precursor and a dipyrromethene derivative. This strategy is very convenient to prepare low-generation dendritic porphyrins. The divergent approach is another well-known methodology for porphyrin dendrimer synthesis, mostly used for the obtainment of high-generation dendrimers. Click chemistry reaction has been advantageous for the development of more complex porphyrin dendritic structures. This reaction presents important advantages, such as high yields and mild reaction conditions which permit the assembly of different multiporphyrin dendritic structures. In the constructs presented in this review, the emission of the porphyrin moiety has been observed, leading to potential applications in artificial photosynthesis, sensing, nanomedicine, and biological sciences.

Intensity-modulated Radiotherapy for Rectal Cancer in the UK in 2020

AIMS

Preoperative (chemo)radiotherapy followed by total mesorectal excision is the current standard of care for patients with locally advanced rectal cancer. The use of intensity-modulated radiotherapy (IMRT) for rectal cancer is increasing in the UK. However, the extent of IMRT implementation and current practice was not previously known. A national survey was commissioned to investigate the landscape of IMRT use for rectal cancer and to inform the development of national rectal cancer IMRT guidance.

MATERIALS AND METHODS

A web-based survey was developed by the National Rectal Cancer IMRT Guidance working group in collaboration with the Royal College of Radiologists and disseminated to all UK radiotherapy centres. The survey enquired about the implementation of IMRT with a focus on the following aspects of the workflow: dose fractionation schedules and use of a boost; pre-treatment preparation and simulation; target volume/organ at risk definition; treatment planning and treatment verification. A descriptive statistical analysis was carried out.

RESULTS

In total, 44 of 63 centres (70%) responded to the survey; 30/44 (68%) and 36/44 (82%) centres currently use IMRT to treat all patients and selected patients with rectal cancer, respectively. There was general agreement concerning several aspects of the IMRT workflow, including patient positioning, use of intravenous contrast and bladder protocols. Greater variation in practice was identified regarding rectal protocols; use of a boost to primary/nodal disease; target volume delineation; organ at risk delineation and dose constraints and treatment verification. Delineation of individual small bowel loops and daily volumetric treatment verification were considered potentially feasible by most centres.

CONCLUSION

This survey identified that IMRT is already used to treat rectal cancer in many UK radiotherapy centres, but there is heterogeneity between centres in its implementation and practice. These results have been a valuable aid in framing the recommendations within the new National Rectal Cancer IMRT Guidance.

Blood CD9+ B cell, a biomarker of bronchiolitis obliterans syndrome after lung transplantation

Bronchiolitis obliterans syndrome is the main limitation for long-term survival after lung transplantation. Some specific B cell populations are associated with long-term graft acceptance. We aimed to monitor the B cell profile during early development of bronchiolitis obliterans syndrome after lung transplantation. The B cell longitudinal profile was analyzed in peripheral blood mononuclear cells from patients with bronchiolitis obliterans syndrome and patients who remained stable over 3 years of follow-up. CD24^hi CD38^hi transitional B cells were increased in stable patients only, and reached a peak 24 months after transplantation, whereas they remained unchanged in patients who developed a bronchiolitis obliterans syndrome. These CD24^hi CD38^hi transitional B cells specifically secrete IL-10 and express CD9. Thus, patients with a total CD9⁺ B cell frequency below 6.6% displayed significantly higher incidence of bronchiolitis obliterans syndrome (AUC = 0.836, PPV = 0.75, NPV = 1). These data are the first to associate IL-10-secreting CD24^hi CD38^hi transitional B cells expressing CD9 with better allograft outcome in lung transplant recipients. CD9-expressing B cells appear as a contributor to a favorable environment essential for the maintenance of long-term stable graft function and as a new predictive biomarker of bronchiolitis obliterans syndrome-free survival.

[Selection of lung transplant candidates in France in 2019]

INTRODUCTION

In 2015, the International Society for Heart and Lung Transplantation (ISHLT) published a consensus document for the selection of lung transplant candidates. In the absence of recent French recommendations, this guideline is useful in order to send lung transplant candidates to the transplantation centers and to list them for lung transplantation at the right time.

BACKGROUND

The main indications for lung transplantation in adults are COPD and emphysema, idiopathic pulmonary fibrosis and interstitial diseases, cystic fibrosis and pulmonary arterial hypertension (PAH). The specific indications for each underlying disease as well as the general contraindications have been reviewed in 2015 by the ISHLT. For cystic fibrosis, the main factors are forced expiratory volume in one second, 6-MWD, PAH and clinical deterioration characterized by increased frequency of exacerbations; for emphysema progressive disease, the BODE score, hypercapnia and FEV1; for PAH progressive disease or the need of specific intravenous therapy and NYHA classification. Finally, the diagnosis of fibrosing interstitial lung disease is usually a sufficient indication for lung transplantation assessment.

OUTLOOK AND CONCLUSION

These new recommendations, close to French practices, help clinicians to find the right time for referral of patients to transplantation centers. This is crucial for the prognosis of lung transplantation.

Synthesis and photophysical properties of novel pyrene–metalloporphyrin dendritic systems

Energy transfer studies were performed on a series of new pyrene–metalloporphyrin (Zn, Cu, Mg and Mn) dendritic constructs.

Energy Transfer in Dendritic Systems Having Pyrene Peripheral Groups as Donors and Different Acceptor Groups

In this feature article, a specific overview of resonance energy transfer (FRET) in dendritic molecules was performed. We focused mainly on constructs bearing peripheral pyrene groups as donor moieties using different acceptor groups, such as porphyrin, fullerene C60, ruthenium-bipyridine complexes, and cyclen-core. We have studied the effect of all the different donor-acceptor pairs in the energy transfer efficiency (FRET). In all cases, high FRET efficiency values were observed.

Retrospective study of thoracotomy performed in a French level 1-trauma center

OBJECTIVE

Resuscitative thoracotomy, a potentially life-saving procedure, is used exceptionally, and essentially for penetrating trauma. Most of the available literature is American while reports from Europe are sparse. We report our experience in a French level 1-trauma center.

MATERIAL AND METHODS

Patient records (patient age, gender, mechanism of injury, indication for emergency thoracotomy, anatomic injuries, interventions and survival) for all patients who underwent emergency thoracotomy between January 2005 and December 2015 were analyzed.

RESULTS

Twenty-two patients (19 males) underwent emergency thoracotomy. Median age was 27.5 (12-67) years. Twelve were performed for blunt trauma (55%) and 10 for penetrating injuries (45%). Thirteen patients presented with cardiac arrest, while nine had deep and refractory hypotension. Overall, survival was 32% (n=7). There were no survivors in the blunt trauma group while seven of ten with penetrating injuries survived. All patients presenting with cardiac arrest died.

CONCLUSION

The survival rate in this French retrospective study was in accordance with the literature.

Global patterns of care in advanced stage mycosis fungoides/Sezary syndrome: a multicenter retrospective follow-up study from the Cutaneous Lymphoma International Consortium

BACKGROUND

Advanced-stage mycosis fungoides (MF)/Sézary syndrome (SS) patients are weighted by an unfavorable prognosis and share an unmet clinical need of effective treatments. International guidelines are available detailing treatment options for the different stages but without recommending treatments in any particular order due to lack of comparative trials. The aims of this second CLIC study were to retrospectively analyze the pattern of care worldwide for advanced-stage MF/SS patients, the distribution of treatments according to geographical areas (USA versus non-USA), and whether the heterogeneity of approaches has potential impact on survival.

PATIENTS AND METHODS

This study included 853 patients from 21 specialist centers (14 European, 4 USA, 1 each Australian, Brazilian, and Japanese).

RESULTS

Heterogeneity of treatment approaches was found, with up to 24 different modalities or combinations used as first-line and 36% of patients receiving four or more treatments. Stage IIB disease was most frequently treated by total-skin-electron-beam radiotherapy, bexarotene and gemcitabine; erythrodermic and SS patients by extracorporeal photochemotherapy, and stage IVA2 by polychemotherapy. Significant differences were found between USA and non-USA centers, with bexarotene, photopheresis and histone deacetylase inhibitors most frequently prescribed for first-line treatment in USA while phototherapy, interferon, chlorambucil and gemcitabine in non-USA centers. These differences did not significantly impact on survival. However, when considering death and therapy change as competing risk events and the impact of first treatment line on both events, both monochemotherapy (SHR = 2.07) and polychemotherapy (SHR = 1.69) showed elevated relative risks.

CONCLUSION

This large multicenter retrospective study shows that there exist a large treatment heterogeneity in advanced MF/SS and differences between USA and non-USA centers but these were not related to survival, while our data reveal that chemotherapy as first treatment is associated with a higher risk of death and/or change of therapy and thus other therapeutic options should be preferable as first treatment approach.

Sex differences in the outcome of juvenile social isolation on HPA axis function in rats

Women are more likely than men to suffer from anxiety disorders and major depression. These disorders share hyperresponsiveness to stress as an etiological factor. Thus, sex differences in brain arousal systems and their regulation by chronic stress may account for the increased vulnerability to these disorders in women. Social isolation is a model of early life stress that results in neurobiological alterations leading to increased anxiety-like and depressive-like behaviors. Here we investigated the sex difference in the effects of post-weaning social isolation on acute stress sensitivity and behavior in rats. In both sexes, social isolation at weaning reduced basal levels of the neuroactive steroid allopregnanolone in the brain and of corticosterone in plasma. Moreover, acute stress increased plasma corticosterone levels in both group-housed and socially isolated male and female rats; however this effect was greater in male than female rats subjected to social isolation. Intriguingly, group-housed female rats showed no change in plasma and brain levels of allopregnanolone after acute foot-shock stress. The absence of stress-induced effects on allopregnanolone synthesis might be due to the physiologically higher levels of this hormone in females vs. males. Accordingly, increasing allopregnanolone levels in male rats blunted the response to foot-shock stress in these animals. Socially isolated male, but not female, rats also display depressive-like behavior and increased hippocampal brain-derived neurotrophic factor (BDNF). The ovarian steroids could "buffer" the effect of this adverse experience in females on these parameters. Finally, the dexamethasone (DEX) suppression test indicated that the chronic stress associated with social isolation impairs feedback inhibition in both sexes in which an increase in the abundance of glucocorticoid receptors (GRs) in the hippocampus was found. Altogether, these results demonstrate that social isolation affects neuroendocrine reactivity to stress, plasticity and emotionality in a sexually dimorphic manner.

Is intra-aortic balloon pump absolutely contraindicated in type A aortic dissection?

AIM

Circulatory failure following surgery for type A aortic dissection is frequent and associated with a high mortality rate. The intra-aortic balloon pump (IABP) is used to treat postcardiotomy cardiogenic shock but aortic dissection is traditionally a contraindication. In 10 patients we used IABP for severe cardiogenic shock following aortic dissection surgery, here we report on the short and midterm results.

METHODS

From January 2000 to April 2008, among 151 patients with type A aortic dissection 10 received a postoperative IABP. False lumen extension was limited to the ascending aorta for 3 patients, reached the arch for 1 and the descending aorta for 6.

RESULTS

The device was placed in the operative room (7 patients), intensive care unit (2) and preoperatively (1). IABP was introduced percutaneously except for one who required surgical placement. The mean duration of IABP therapy was 3.8 days. Four patients died, but no death was directly related to IABP. Improvement in hemodynamics allowed 8 patients to be weaned off IABP. None suffered extension of the dissection. Two patients developed IABP-related complications. Six required extrarenal purification. Among the survivors, one died of a stroke at 38 months, 2 recovered the same quality of life and 3 had neurological sequelae without loss of autonomy.

CONCLUSION

IABP should only be used as a salvage option in cases of severe cardiogenic shock following type A aortic dissection. No patient suffered device-related aortic rupture or extension of the dissection. High mortality and morbidity underline the gravity of cardiogenic shock in this setting.

Neonatal exposure to estradiol decreases hypothalamic allopregnanolone concentrations and alters agonistic and sexual but not affective behavior in adult female rats

Exposure of developing female rats to estradiol during the perinatal period induced long-lasting dysregulation of gonadal axis and decreased cerebrocortical and plasma concentrations of allopregnanolone. We have now examined the effects of neonatal estradiol administration in female rats on hypothalamic allopregnanolone concentrations and on exploratory, affective, agonistic and sexual behaviors as well as social learning. A single administration of β-estradiol 3-benzoate (EB, 10μg) on the day of birth resulted in a delay of vaginal opening, acyclicity and ovarian failure. These alterations were associated with a significant decrease in the concentrations of allopregnanolone in the hypothalamus at 21 and 60days, but not at 7days, after birth. Neonatal administration of EB also increased agonistic behaviors in adult rats, such as dominant behaviors and following of an ovariectomized intruder, while living attacks unaffected. EB-treated rats showed also an increase in anogenital investigation, associated with a drastic reduction in spontaneous and induced female sexual behaviors (receptivity and proceptivity). In contrast, neonatal administration of EB did not affect locomotor activity, anxiety- and mood-related behaviors, the social transmission of flavor preferences, and seizures sensitivity. These effects of estradiol suggest that it plays a major role in regulation of both the abundance of allopregnanolone and the expression of agonistic and sexual behaviors, while failing to influence affective behaviors and social learning. Thus, the pronounced and persistent decrease in hypothalamic allopregnanolone concentration may be related to the manifestation of agonistic and sexual behaviors.

Association of pre-transplantation positron emission tomography/computed tomography and outcome in mantle cell lymphoma

Positron emission tomography/computed tomography (PET/CT)-positive findings before autologous SCT (auto-SCT) are associated with inferior PFS and OS in patients with relapsed Hodgkin's and diffuse large B-cell lymphoma. We classified pre-transplant PET/CT performed before auto-SCT as positive or negative to evaluate the impact of pre-transplant PET/CT in mantle cell lymphoma (MCL). In 29 patients, 17 were PET/CT(-) and 12 were PET/CT(+). PET/CT(+) patients were younger (P=0.04), had lower MCL International Prognostic Index (MIPI, P=0.04) scores, but increased bulky adenopathy >5 cm (45% vs 13%, P=0.09). With a median follow-up of 27 months (range: 5-55 months), 7 patients relapsed (4 in the PET/CT(-) group and 3 in the PET/CT(+) group) with 2 deaths in the PET/CT(+) group without a documented relapse. The estimated 2-year PFS was 64% (95% confidence interval (CI): 0.30-0.85) vs 87% (95% CI: 0.57-0.97) in PET/CT(+) and PET/CT(-) patients, respectively (P=0.054). OS was significantly decreased in PET/CT(+) patients (P=0.007), with 2-year estimates of 60% (95% CI: 0.23-0.84) vs 100% in PET/CT(-) patients. A positive pre-transplant PET/CT is associated with a poor prognosis in patients with MCL. Additional factors may impact the prognostic value of PET/CT, as several PET/CT(+) patients remain in remission.

Phase I trial of subcutaneous (SQ) alemtuzumab (A) and CHOP in T-cell lymphoma: Preliminary results

7594

Background: T-cell lymphomas are highly chemoresistant. Cure rates with combination chemotherapy do not exceed 25–30%. We showed that A, a humanized IgG1 targeting the CD52 antigen expressed on most human leukocytes, is cytotoxic for malignant T-cells in vitro and in vivo, regardless of p53 mutational status (Blood 106, 3380, 2005). Thus, we initiated a Phase I study with A and CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) in T-cell lymphoma. Methods: Accrual goal: 15–18 patients (pts) with untreated (u) or relapsed (r) peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL), excluding ALK-1-positive anaplastic large cell lymphoma. Primary objective: maximal tolerated dose (MTD). All pts receive single agent SQ A loading (3, 10, 30 mg) over 5 days, followed by one SQ A dose with each CHOP every 21 days for a total of 8 cycles. A dose levels: 3, 10, 20 and 30 mg. All pts receive valacyclovir and trimethoprim-sulfamethoxasole, plus G-CSF and erythropoietin according to guidelines. Results: Eight of the nine enrolled pts on cohort 1 (A=3 mg) and cohort 2 (A=10 mg) are evaluable for toxicity (uPTCL= 4, rPTCL=1, rCTCL=3). All pts completed single agent A loading on time and tolerated well further SQ A. No cycle was delayed due to myelosuppression. There were no opportunistic infections or neutropenic fevers. Four pts completed all planned therapy. Three pts did not complete therapy due to progression (2) or toxicity (1). One pt remains on study after 4 cycles. There were no Grade 4 adverse events (AEs). Grade 3 AEs included fatigue (1), anemia (1), dyspnea (1) and emesis (1). Cohort 1 was expanded due asymptomatic cytomegalovirus [CMV] reactivation requiring hospitalization for thrice daily foscarnet, thus resulting in Grade 3 AE. Protocol was amended and subsequent asymptomatic CMV reactivations (2) were treated with oral valganciclovir. No symptomatic CMV reactivation occurred. Conclusions: At current dose levels, SQ A can be easily and safely administered with CHOP chemotherapy and growth factor support, without excessive myelosuppression or infectious AEs. Asymptomatic CMV reactivation can be managed with oral valganciclovir. Further A dose escalation is in progress.

[Table: see text]