A fixed-duration immunochemotherapy approach in CLL: 5.5-year results from the phase 2 ICLL-07 FILO trial

In previously untreated, medically fit patients with chronic lymphocytic leukemia (CLL), research is focused on developing fixed-duration strategies to improve long-term outcomes while sparing patients from serious toxicities. The ICLL-07 trial evaluated a fixed-duration (15-month) immunochemotherapy approach in which after obinutuzumab-ibrutinib induction for 9 months, patients (n = 10) in complete remission (CR) with bone marrow (BM) measurable residual disease (MRD) <0.01% continued only ibrutinib 420 mg/day for 6 additional months (I arm), whereas the majority (n = 115) received up to 4 cycles of fludarabine/cyclophosphamide-obinutuzumab 1000 mg alongside the ibrutinib (I-FCG arm). Primary analysis at month 16 showed that 84 of 135 (62.2%) patients enrolled achieved CR with a BM MRD <0.01%. Here, we report follow-up at median 63 months. Peripheral blood (PB) MRD was assessed 6 monthly beyond the end of treatment using a highly sensitive (10-6) flow cytometry technique. In the I-FCG arm, the PB MRD <0.01% rate (low-level positive <0.01% or undetectable with limit of detection ≤10-4) in evaluable patients was still 92.5% (74/80) at month 40 and 80.6% (50/62) at month 64. No differences in the PB MRD status were apparent per to the IGHV mutational status. In the overall population, 4-year progression-free and overall survival rates were 95.5% and 96.2%, respectively. Twelve deaths occurred overall. Fourteen serious adverse events occurred beyond the end of treatment. Thus, our fixed-duration immunochemotherapy approach produced deep and sustained PB MRD responses, high survival rates, and low long-term toxicity. A randomized trial is needed to compare our immunochemotherapy approach with a chemotherapy-free strategy. This trial was registered at www.clinicaltrials.gov as #NCT02666898.

Clinical outcome of therapy-related acute myeloid leukemia patients. Real-life experience in a University Hospital and a Cancer Center in France

BACKGROUND

t-AML occurs after a primary malignancy treatment and retains a poor prognosis.

AIMS

To determine the impact of primary malignancies, therapeutic strategies, and prognostic factors on clinical outcomes of t-AML.

RESULTS

A total of 112 adult patients were included in this study. Fifty-Five patients received intensive chemotherapy (IC), 33 non-IC, and 24 best supportive care. At t-AML diagnosis, 42% and 44% of patients presented an unfavorable karyotype and unfavorable 2010 ELN risk profile, respectively. Among treated patients (n = 88), 43 (49%) achieved complete remission: four out of 33 (12%) and 39 out of 55 (71%) in non-IC and IC groups, respectively. With a median follow-up of 5.5 months, the median overall survival (OS) and disease-free survival (DFS) for the whole population were 9 months and 6.3 months, respectively, and for the 88 treated patients 13.5 months and 8.2 months, respectively. Univariate analysis on OS and DFS showed a significant impact of high white blood cells (WBC) and blast counts at diagnosis, unfavorable karyotype and ELN classification. Multivariate analysis showed a negative impact of WBC count at diagnosis and a positive impact of chemotherapy on OS and DFS in the whole population. It also showed a negative impact of previous auto-HCT and high WBC count on OS and DFS and of IC on OS in treated patients which disappeared when we considered only confounding variables (age, previous cancers, marrow blasts, and 2010 ELN classification). In a pair-matched analysis comparing IC treated t-AML with de novo AML, there was no difference of OS and DFS between the two populations.

CONCLUSION

We showed, in this study that t-AML patients with unfavorable features represented almost half of the population. Best outcomes obtained in patients receiving IC must be balanced by known confounding variables and should be improved by using new innovative agents and therapeutic strategies.

Progressive erythrocytosis under lenvatinib treatment in patients with advanced hepatocellular carcinoma

PURPOSE

This manuscript reports on the occurrence of early and frequent erythrocytosis in advanced hepatocellular carcinoma (HCC) patients treated with lenvatinib.

METHODS

A cohort of 23 patients with advanced HCC, treated with this antiangiogenic drug for at least one month, was retrospectively analyzed.

RESULTS

These patients (82.7% men, median age 58.3, cirrhosis in 60.8%) were treated between October 2019 and September 2020 with lenvatinib, as first-line systemic therapy for 82.6% of them. For 20 patients (87%), an early and significant increase in hemoglobin (Hb) level, up to 1.41 g/dL (p < 0.001) was reported and remained elevated. Ten patients (43.5%), all men, reached erythrocytosis (Hb > 16.5 g/dL), 7 were treated with low-dose aspirin for primary thromboprophylaxis and 2 needed phlebotomy. None underwent thromboembolic complications. A significant Hb decrease was observed after treatment discontinuation (p < 0.05). Erythropoietin (EPO) serum levels also increased, which was attributed to HCC after immunostaining for EPO in liver biopsies. The Naranjo adverse drug reaction probability scale documented the relationship between erythrocytosis and lenvatinib and regression at treatment discontinuation. Erythrocytosis was hypothesized to be a class effect of anti-VEGF therapies, the magnitude of which might depend on the IC50 value of each molecule.

CONCLUSION

This report documents the frequent occurrence of erythrocytosis during lenvatinib treatment for advanced HCC, likely secondary to EPO secretion by tumor cells through the antiangiogenic activity levatinib. An early and close monitoring of hematologic parameters is, thus, recommended, together with thromboprophylaxis by low-dose aspirin and phlebotomy in case of symptomatic erythrocytosis.

Outcome after allogeneic stem cell transplantation with haploidentical versus HLA-matched donors in patients with higher-risk MDS

Allogeneic hematopoietic stem cell transplantation remains the best curative option for higher-risk myelodysplastic syndrome. The presence of monosomal karyotype and/or complex karyotype abnormalities predicts inferior survival after allo-SCT in MDS patients. Haploidentical allo-SCT has been increasingly used in acute leukemia (AL) and has similar results as using HLA-matched donors, but data on higher-risk MDS is sparse. We compared outcomes in 266 patients with higher-risk MDS after HLA-matched sibling donor (MSD, n = 79), HLA-matched unrelated donor (MUD, n = 139) and HLA haploidentical donor (HID, n = 48) from 2010 to 2019. Median donor age differed between the three groups (p < 0.001). The overall survival was significantly different between the three groups with a better OS observed in the MUD group (p = 0.014). This observation could be explained by a higher progression-free survival with MUD (p = 0.014). The cumulative incidence of grade 2-4 acute GvHD was significantly higher in the HID group (p = 0.051). However, in multivariable analysis, patients transplanted using an HID had comparable mortality to patients transplanted using a MUD (subdistribution hazard ratio [sHR]: 0.58 [0.32-1.07]; p = 0.080) and a MSD ([sHR]: 0.56 [0.28-1.11]; p = 0.094). MUD do not remain a significant positive predictor of survival, suggesting that beyond the donor-recipient HLA matching, the donor age might impact recipient outcome.

Machine-learning score using stress CMR for death prediction in patients with suspected or known CAD

Background

In patients with suspected or known coronary artery disease (CAD), traditional prognostic risk assessment is based upon a limited selection of clinical and imaging findings. Machine learning (ML) methods can take into account a greater number and complexity of variables.

Purpose

To investigate the feasibility and accuracy of ML using stress CMR and clinical data to predict 10-year all-cause mortality in patients with suspected or known CAD, and compared its performance to existing clinical or CMR scores.

Methods

Between 2008 and 2018, a retrospective cohort study with a median follow-up of 6.0 years (interquartile range: 5.0–8.0) included all consecutive patients referred for stress CMR. Twenty-three clinical and 11 stress CMR parameters were evaluated. Machine learning involved automated feature selection by random survival forest, model building with a multiple fractional polynomial algorithm, and 5 repetitions of 10-fold stratified cross-validation. The primary outcome was all-cause death based on the electronic National Death Registry. The external validation cohort of the ML score was performed in another center.

Results

Of 31,752 consecutive patients (mean age 63.7±12.1 years and 65.7% males), 2,679 (8.4%) died with 206,453 patient-years of follow-up. ML score (ranging 0 to 10 points) exhibited a higher area-under-the-curve compared with C-CMR-10-score, ESC-score, QRISK3-score, FRS and stress CMR data alone for prediction of 10-year all-cause mortality (ML: 0.76 vs. C-CMR-10-score: 0.68, ESC-score: 0.66, QRISK3-score: 0.64, FRS: 0.63, extent of inducible ischemia: 0.66, extent of LGE: 0.65, all p&lt;0.001). The ML score exhibited also a good area-under-the-curve in the external cohort (AUC: 0.75).

Conclusions

The ML score including clinical and stress CMR data exhibited a higher prognostic value to predict 10-year death compared with all traditional clinical or CMR scores.

Funding Acknowledgement

Type of funding sources: None.

Kinetics of early and late molecular recurrences after first-line imatinib cessation in chronic myeloid leukemia: updated results from the STIM2 trial

Discontinuation of tyrosine kinase inhibitors in chronic phase chronic myeloid leukemia is feasible in clinical practice based on recently published international recommendations. Nevertheless, factors predictive of molecular recurrence have not been fully elucidated and long-term follow-up of patients enrolled in clinical studies are required in order to update knowledge on discontinuation attempts particularly in terms of the safety and durability of treatment-free remission (TFR). In the current study, we updated results from the STIM2 study in the light of the consensual criterion of molecular recurrence reported in different international recommendations. Among the 199 patients included in the perprotocol study, 108 patients lost a major molecular response. With a median follow-up of 40.8 months (5.5-111 months), the probability of treatment-free remission was 43.4% [36.3-50.4] at 5 years, 40.9% [32.8-47.3] at 7 years and 34.5% [25.6- 43.3] at 9 years. Molecular recurrence occurred between 0 to 6 months, 6 to 24 months and after 24 months in 75 patients (69%), 15 patients (14%) and 18 patients (17%), respectively. Notably, the kinetics of molecular recurrence differed significantly between these three subgroups with a median time from loss of MR4 (BCR::ABL1 IS≤0.01%) to loss of major molecular response of 1, 7 and 22 months, respectively. Predictive factors of molecular recurrence differed according to the time of occurrence of the molecular recurrence. Durations of imatinib treatment and deep molecular response as well as BCR::ABL1/ABL1 levels at cessation of tyrosine kinase inhibitor treatment, as quantified by reverse transcriptase droplet digital polymerase chain reaction, are involved in molecular recurrence occurring up to 24 months but not beyond. (ClinicalTrial. gov Identifier NCT#0134373).

Antifungal Prophylaxis in AML Patients Receiving Intensive Induction Chemotherapy: A Prospective Observational Study From the Acute Leukaemia French Association (ALFA) Group

BACKGROUND

Although recommended in patients with acute myeloblastic leukaemia (AML) after induction chemotherapy, real-life use of antifungal prophylaxis (AFP) is different among centres.

MATERIALS AND METHODS

This is an ancillary study to a randomized trial on intensive induction chemotherapy in AML patients (ALFA-0702/NCT00932412), where AFP with posaconazole was recommended. IFIs were graded by investigators and by central reviewers according to the revised EORTC definitions. Experts conclusions were compared to the investigators' ones.

RESULTS

A total of 677 patients were included. Four AFP strategies were reported: Group-1: no AFP (n = 203, 30%), Group-2: posaconazole (n = 241, 36%), Group-3: posaconazole with other AFP (n = 142, 21%), Group-4: other AFP (n = 91, 13%). Experts graded more IFI than investigators: proven/probable IFI, 9.0% (n = 61) versus 6.2% (n = 42). The cumulative incidence at day60 of probable/proven IFI was 13.9% (Group-1); 7.9% (Group-2); 5.6% (Group-3); and 6.6% (Group-4). IFI onset was 26 (19-31) days after induction in Groups 2-3, versus 16 (9-25) days in Group 1 and 20 (12-24) days in Group 4 (P< .001). After a median follow-up of 27.5 months (0.4-73.4), the mortality rate was 38.3%, with 5.4% attributed to IFI. In multivariate analysis, IFI occurrence was an independent risk of death (HR5.63, 95%-CI 2.62-12.08, P< .001). EORTC recommendations were applied in only 57% of patients. In patients without IFI, the rate of AML complete remission was higher.

CONCLUSIONS

In AML patients, AFP delayed the onset of IFI in addition of decreasing their rate. The frequent misidentification of IFI impacts their appropriate management according to recommendations. hematological remission was more frequent in patients without IFI.

Machine-learning score using stress CMR for death prediction in patients with suspected or known CAD

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND

In patients with suspected or known coronary artery disease (CAD), traditional prognostic risk assessment is based upon a limited selection of clinical and imaging findings. Machine learning (ML) methods can take into account a greater number and complexity of variables.

PURPOSE

To investigate the feasibility and accuracy of ML using stress CMR and clinical data to predict 10-year all-cause mortality in patients with suspected or known CAD, and compared its performance to existing clinical or CMR scores.

METHODS

Between 2008 and 2018, a retrospective cohort study with a median follow-up of 6.0 years (interquartile range: 5.0-8.0) included all consecutive patients referred for stress CMR. Twenty-three clinical and 11 stress CMR parameters were evaluated. Machine learning involved automated feature selection by random survival forest, model building with a multiple fractional polynomial algorithm, and 5 repetitions of 10-fold stratified cross-validation. The primary outcome was all-cause death based on the electronic National Death Registry.

RESULTS

Of 31,752 consecutive patients (mean age 63.7 ± 12.1 years and 65.7% males), 2,679 (8.4%) died with 206,453 patient-years of follow-up. ML score (ranging 0 to 10 points) exhibited a higher area-under-the-curve compared with C-CMR-10-score, ESC-score, QRISK3-score, FRS and stress CMR data alone for prediction of 10-year all-cause mortality (ML: 0.76 vs. C-CMR-10-score: 0.68, ESC-score: 0.66, QRISK3-score: 0.64, FRS: 0.63, extent of inducible ischemia: 0.66, extent of LGE: 0.65, all p &lt; 0.001).

CONCLUSIONS

The ML score including clinical and stress CMR data exhibited a higher prognostic value to predict 10-year death compared with all traditional clinical or CMR scores. Abstract Figure. Random survival Forest: ML score  Abstract Figure. Prognostic Value of ML score

Long-term prognostic value of stress CMR-related coronary revascularization to predict death: a large registry with &gt; 200,000 patient-years of follow-up

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND

While the benefit of coronary revascularization in patients with stable coronary artery disease (CAD) is debated, data assessing the potential interest of stress CMR to guide coronary revascularization are limited.

PURPOSE

To assess the long-term prognostic value of stress CMR-related coronary revascularization in consecutive patients from a large registry.

METHODS

Between 2008 and 2018, a retrospective cohort study with a median follow-up of 6.0 years (interquartile range: 5.0-8.0) included all consecutive patients referred for stress CMR. Stress CMR-related coronary revascularization was defined by any coronary revascularization performed within 90 days after CMR. The primary outcome was all-cause death based on the electronic National Death Registry.

RESULTS

Among the 31,752 consecutive patients (mean age 63.7 ± 12.1 years and 65.7% males), 2,679 (8.4%) died at 206,453 patient-years of follow-up. Inducible ischemia and late gadolinium enhancement (LGE) by CMR were associated with death (both p &lt; 0.001). In multivariable Cox regression, inducible ischemia and LGE were independent predictors of death (HR = 1.61; 99.5%CI 1.41-1.84; HR = 1.62; 99.5%CI 1.41-1.86, respectively; p &lt; 0.001). CMR-related coronary revascularization was an independent predictor of greater survival (HR: 0.66; 99.5%CI: 0.52-0.84; p &lt; 0.001). CMR-related revascularization was associated with a lower incidence of death in patients with severe inducible ischemia (p &lt; 0.001), but showed no benefit in patients with mild or moderate ischemia (p = 0.109).

CONCLUSIONS

In this large observational series of consecutive patients, stress perfusion CMR had important incremental long-term prognostic value to predict death over traditional risk factors. CMR-related revascularization was associated with a lower incidence of death in patients with severe ischemia.

Relationship between sensitive skin and sleep disorders, fatigue, dust, sweating, food, tobacco consumption or female hormonal changes: Results from a worldwide survey of 10 743 individuals

BACKGROUND

Sensitive skin is related to environmental factors.

OBJECTIVES

We aimed to investigate the roles of poorly known associated and triggering factors on sensitive skin in a large global population.

METHODS

A survey was administrated to a representative sample of the adult population aged 18-75 years in five different countries (Brazil, China, France Russia, and the United States). All participants answered a web-based questionnaire on sociodemographic characteristics, sensitive skin and environmental factors.

RESULTS

Among the 10 743 included individuals (5285 men and 5458 women), 48.2% declared that they had sensitive skin. The group with sensitive skin reported significant increases in fatigue, dust or sweating and to a lesser extent food or tobacco consumption. The members of this group also declared that they experienced more sleep disorders than individuals without sensitive skin. Sensitive skin was very frequent in pregnant women, women with painful menstruations or women using contraceptive pills.

CONCLUSIONS

This large cohort study identified new factors, including female hormonal status, fatigue, sleep disorders and food, associated with sensitive skin. These associations suggest that sensitive skin is not restricted to an epidermal disorder but may be included in a larger context. The identified factors are potential upstream drivers of neurogenic inflammation in sensitive skin.

Impact of second decline rate of BCR-ABL1 transcript on clinical outcome of chronic phase chronic myeloid leukemia patients on imatinib first-line

Early molecular response has been associated with clinical outcome in chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors. The BCR-ABL1 transcript rate decline from baseline to 3 months has been demonstrated to be more predictive than a single BCR-ABL1 level at 3 months (M3). However, it cannot be used routinely because ABL1, as an internal gene control, is not reliable for BCR-ABL1 quantification above 10%. This study aimed to compare clinical outcome and molecular response of chronic phase CML patients, depending on the percentage of BCR-ABL1 transcript decrease from month 3 to month 6 using ABL1 as an internal control gene. Two hundred sixteen chronic phase CML patients treated with imatinib 400 mg for whom M3 and month 6 molecular data were available were included in the study. Associations with event-free (EFS), failure-free (FFS), progression-free (PFS), and overall survivals (OS) molecular response 4 log and 4.5 log were assessed. The percentage of BCR-ABL1 decline from month 3 to month 6 was significantly linked to the EFS and the FFS (p < 0.001). A common cut-off of 67% of decline predicted the better risk of event. Patients with a decrease below 67% have worse EFS and FFS as compared to those having a higher decrease (p < 0.001). The impact was confirmed by multivariate analysis. Since the slope between diagnosis and 3 months cannot be reliable using ABL1 as an internal gene control, the second decline rate of BCR-ABL1 transcript between month 3 and month 6 could efficiently identify patients at higher risk of event.

Chronic disseminated candidiasis and acute leukemia: Impact on survival and hematopoietic stem cell transplantation agenda

OBJECTIVES

To study the management of chronic disseminated candidiasis (CDC) in patients presenting with acute leukemia.

PATIENTS AND METHODS

Single-center retrospective study of acute leukemia patients (2006-2015) to investigate three aspects of CDC: its impact on the time interval between diagnosis and hematopoietic stem cell transplantation, when required (non-parametric Wilcoxon-Mann-Whitney test); its impact on overall survival (Cox proportional hazard regression model); antifungal therapeutic strategies implemented.

RESULTS

A total of 639 patients presenting with acute leukemia were included; 144 were transplanted and 29 developed CDC. CDC did not significantly increase the time interval between diagnosis and transplantation, nor did it impact the overall survival of recipients. An improved overall survival was observed in non-transplanted acute leukemia patients presenting with CDC.

CONCLUSION

CDC should not postpone transplantation if antifungal treatment is optimized.

The impact of HLA matching on long-term transplant outcome after allogeneic hematopoietic stem cell transplantation for CLL: a retrospective study from the EBMT registry

We analyzed 368 chronic lymphocytic leukemia patients who underwent allogeneic hematopoietic stem cell transplantation reported to the EBMT registry between 1995 and 2007. There were 198 human leukocyte antigen (HLA)-identical siblings; among unrelated transplants, 31 were well matched in high resolution ('well matched' unrelated donor, WMUD), and 139 were mismatched (MM), including 30 matched in low resolution; 266 patients (72%) received reduced-intensity conditioning and 102 (28%) received standard. According to the EBMT risk score, 11% were in scores 1-3, 23% in score 4, 40% in score 5, 22% in score 6 and 4% in score 7. There was no difference in overall survival (OS) at 5 years between HLA-identical siblings (55% (48-64)) and WMUD (59% (41-84)), P=0.82. In contrast, OS was significantly worse for MM (37% (29-48) P=0.005) due to a significant excess of transplant-related mortality. Also OS worsened significantly when EBMT risk score increased. HLA matching had no significant impact on relapse (siblings: 24% (21-27); WMUD: 35% (26-44), P=0.11 and MM: 21% (18-24), P=0.81); alemtuzumab T-cell depletion and stem cell source (peripheral blood) were associated with an increased risk. Our findings support the use of WMUD as equivalent alternative to HLA-matched sibling donors for allogeneic HSCT in CLL, and justify the application of EBMT risk score in this disease.

Autoregulation of McA-RH7777 hepatoma cell proliferation by histamine H3 receptors

Previous studies have suggested that histamine (HA) acts as an autocrine growth factor. We have explored the modulation of cell proliferation by HA using McA-RH7777 hepatoma cells. High L-histidine decarboxylase (HDC) expression and HA synthesis were found in McA-RH7777 cells. Whereas extracellular HA reached submicromolar concentrations, intracellular levels were very low, indicating that HA was secreted by the cells. McA-RH7777 cells also express H3-receptor (H3R) transcripts and proteins. Reverse transcriptase-polymerase chain reaction analysis detected only transcripts for the long isoform. Immunocytochemistry performed with a selective H3R antibody showed that most cells were immunoreactive. H3R binding sites (Bmax approximately 30 fmol/mg protein) were identified when [125I] iodoproxyfan binding was displaced by the agonist imetit. High-affinity binding also occurred at cytochrome P450 enzymes. This binding was not inhibited by HA, H3R agonists, or by a nonimidazole H3R antagonist but was displaced by imidazole H3R antagonists or by ketoconazole, a imidazole-containing cytochrome inhibitor. HA inhibited proliferation of McA-RH7777 hepatoma cells. The absence of uptake system, its much higher potency at H3Rs, and its low intracellular levels suggested that HA interacted with H3Rs rather than cytochromes. In agreement, both imidazole H3R antagonists, a nonimidazole H3R antagonist, and the HDC inhibitor alpha-monofluoromethyl histidine increased cell proliferation (up to approximately 60%), revealing a H3R-mediated inhibition by endogenous HA. Moreover, exogenous HA inhibited the increase induced by alpha-FMH or H3R antagonists with a nanomolar potency. In conclusion, our findings show that HA regulates proliferation of McA-RH7777 hepatoma cells by interacting with autoinhibitory H3Rs.

Ultrasound-guided coxofemoral arthrocentesis in horses

REASON FOR PERFORMING STUDY

Coxofemoral joint pain is probably underestimated due to difficulties in identifying hip pain. The deep location of the joint and proximity of the sciatic nerve make arthrocentesis based on external landmarks a difficult and potentially risky procedure in mature horses.

OBJECTIVES

To describe an ultrasound-guided injection technique of the coxofemoral joint in standing horses and to evaluate its accuracy and potential difficulties/complications.

METHODS

Nine mature horses had both pelvic areas prepared for sterile ultrasound examination (3.5 MHz curvilinear probe). Coxofemoral joints were located and penetrated at their craniodorsolateral aspect under ultrasonographic guidance and injected with sterile contrast medium. A standing ventrodorsal radiographic view of each hemipelvis centred on the hip was obtained for each horse to assess the injection site. Horses were evaluated for 10 days following injection for possible complications.

RESULTS

Intra-articular injection was successful in all 18 joints. The procedure was well tolerated by horses under minimal restraint. Mean +/- s.d. needle repositionings required before accurate placement was 1.5 +/- 1.3 per joint. Once the needle was in the joint, synovial fluid was obtained in 7/18 joints. Minimal periarticular contrast medium was detected in 2/18 joints. Mean +/- s.d. ultrasonographic examination time required for coxofemoral localisation, accurate needle positioning and injection was 4.3 +/- 2.1 min. No complications were observed in the 10 days following injection.

CONCLUSION

The ultrasound-guided coxofemoral arthrocentesis is an accurate, reliable and safe technique that offers a real time evaluation of needle introduction into the deep and narrow coxofemoral joint space.

POTENTIAL RELEVANCE

Although this technique remains to be tested on clinical cases, it is a promising tool to facilitate diagnosis of coxofemoral pain, septic arthritis or administration of intra-articular medication.

Wave-packet study of H2 formation on a graphite surface through the Langmuir–Hinshelwood mechanism

We have studied the formation of the H2 molecule on a graphite surface, when both H atoms are initially physisorbed. The graphite surface is assumed to be planar. The interaction potential is modeled to reproduce the experimental properties of H physisorption on graphite. Extending our previous work [S. Morisset, F. Aguillon, M. Sizun, and V. Sidis, J. Chem. Phys. 121, 6493 (2004)], full-dimensionality quantum calculations are presented for collision energies ranging from 4 to 50 meV. It is shown that the reaction occurs with a large cross section and produces the H2 molecule with a considerable amount of vibrational energy. The mechanism is either direct or involves the formation of an intermediate complex.

Quantum dynamics of H2 formation on a graphite surface through the Langmuir Hinshelwood mechanism

We have studied the formation of the H2 molecule on a graphite surface, when both H atoms are initially physisorbed. The graphite surface is assumed to be planar, and a model potential is obtained in a semiempirical way to reproduce the experimental properties of H physisorption on graphite. The reaction probability has been computed in the case when the angular momentum of the relative H-H motion lies parallel to the surface plane. Three-dimensional wave packet calculations have been performed for collision energies ranging from 2 to 50 meV. It is shown that the reaction occurs with a significant probability and produces the H2 molecule with a considerable amount of vibrationnal energy. A simple mechanical model is presented, where desorption of the nascent H2 molecule results from two successive binary elastic collisions.

Therapeutic implications of constitutive activity of receptors: the example of the histamine H3 receptor

Some G-protein-coupled receptors display constitutive activity, that is spontaneous activity in the absence of agonist: a proportion of the receptor population adopts a conformation that can bind and activate G proteins. Whereas this was mainly shown to occur with recombinant or pathologically mutated receptors, the physiological relevance of the process has remained debated. We have adressed this question in the case of the histamine H3 receptor, a presynaptic inhibitory receptor regulating histamine release in brain. Having identified a neutral antagonist and inverse agonists with variable intrinsic activity, we show that the native H3 receptor in brain displays high constitutive activity in vitro and, in vivo, controls the release of endogenous histamine. This implies that inverse agonists with high intrinsic activity should be preferred for therapeutic application as "cognitive enhancers" in several psychiatric disorders.

Effects of histamine H3 receptor agonist and antagonist on histamine co-transmitter expression in rat brain

The histaminergic H3-receptor (H3R) controls histamine synthesis and release in the tuberomamillary nucleus. We evaluated the effects of stimulating or blocking of H(3)R on glutamate-decarboxylase 67 kDa (GAD-67) and galanin mRNA expression, two histamine co-transmitters.After in situ hybridization histochemistry (ISHH), we observed a colocalization of 100% between histidine decarboxylase (HDC) and GAD-67 or H3R and of 80 to 97% with galanin. Adult rats received an H3R agonist ((R)alpha-Methylhistamine) or antagonist (ciproxifan) and were sacrificed 1 or 3 hours later. Treatment effects on HDC, galanin and GAD-67 mRNA were studied by quantitative ISHH on serial sections. Treatment with the H3R agonist known to decrease histamine neuron activity initially reduced HDC and galanin gene expression but an inverse change, presumably reflecting a compensatory mechanism, was observed after 3 h on both markers. In contrast, the H3R antagonist known to activate histamine neurons, had opposite effects on the two markers, suggesting that co-transmitters are submitted to independent control mechanisms. Furthermore, GAD-67 mRNA levels were not significantly modified by these treatments.

Acute and chronic effects of methamphetamine on tele-methylhistamine levels in mouse brain: selective involvement of the D(2) and not D(3) receptor

We have explored the role of endogenous dopamine in the control of histaminergic neuron activity in mouse brain regions evaluated by changes in tele-methylhistamine (t-MeHA) levels. In vitro, methamphetamine released [(3)H]noradrenaline but failed to release [(3)H]histamine from synaptosomes. In vivo, methamphetamine enhanced t-MeHA levels by about 2-fold with ED(50) values of approximately 1 mg/kg in caudate putamen, nucleus accumbens, cerebral cortex, and hypothalamus. This response selectively involved the D(2) and not the D(3) receptor as indicated by its blockade by haloperidol and by its persistence after administration of nafadotride, a D(3) receptor preferential ligand, or in (-/-) D(3) receptor-deficient mice. The t-MeHA response to methamphetamine was delayed compared with the locomotor-activating effect of this drug, suggesting that it is of compensatory nature. In agreement, ciproxifan, an inverse agonist known to enhance histamine neuron activity, decreased the hyperlocomotion induced by methamphetamine. Repeated methamphetamine administration resulted in the expected sensitization to the hyperlocomotor effect of the drug but did not modify either the ED(50) or the E(max) regarding t-MeHA levels. However, it resulted in an enhanced basal t-MeHA level (+30-40%), which was sustained for at least 11 days after withdrawal in hypothalamus, striatum, and cerebral cortex and suppressed by haloperidol. Hence, both the acute and chronic administration of methamphetamine enhance histamine neuron activity, presumably in a compensatory manner. Repeated methamphetamine administration also resulted in a modified balance in the opposite influences of dopamine and serotonin on histaminergic neurons as revealed by the enhanced response to haloperidol and abolished response to ketanserin, respectively.

Histamine H3-receptor-mediated [35S]GTP gamma[S] binding: evidence for constitutive activity of the recombinant and native rat and human H3 receptors

Constitutive activity of the recombinant and native rat and human H(3) receptors (H(3)Rs) was studied using H(3)R-mediated [(35)S]GTPgamma[S] binding and [(3)H]-arachidonic acid release. Ciproxifan, an inverse agonist at the rat H(3)R (rH(3)R), decreased [(3)H]arachidonic acid release from CHO cells expressing moderate densities (approximately 200 - 300 fmol mg(-1) protein) of the human H(3)R (hH(3)R). This effect occurred with the same magnitude than at the rH(3)R. The expression of the hH(3)R was associated with an increase in [(35)S]GTPgamma[S] binding to membranes of CHO cells. Ciproxifan decreased [(35)S]GTPgamma[S] binding to membranes of CHO (hH(3)R) cells. Both effects were correlated to receptor density and revealed that constitutive activity of the hH(3)R, although lower than that of the rH(3)R in this assay, was again observed at physiological densities (<500 fmol mg(-1) protein). Ciproxifan was less potent at the human than the rat receptor, not only as an antagonist (K(i)=45 nM), but also as an inverse agonist (EC(50)=15 nM). Constitutive activity of the hH(3)R was also evidenced using inhibition of [(35)S]GTPgamma[S] binding by unlabelled GTPgammaS. The expression of the hH(3)R generated a high affinity binding for GTPgammaS which was increased by imetit, but partially decreased by ciproxifan, therefore acting as a partial inverse agonist. [(35)S]GTPgamma[S] binding to rat brain membranes was decreased in several regions by thioperamide, ciproxifan and FUB 465, three inverse agonists at the H(3)R, whose effects were blocked by proxyfan, a neutral antagonist. [(35)S]GTPgamma[S] binding was also decreased by an A(1)-adenosine receptor inverse agonist, but remained unchanged in the presence of inverse agonists at D(2)/D(3) dopamine, H(1) and H(2) histamine, alpha(2)-adrenergic and delta opioid receptors. In conclusion, the present study shows that the recombinant rat and human H(3) receptors expressed at physiological densities display constitutive activity and suggests that constitutive activity of native H(3)Rs is one of the highest among G-protein-coupled receptors present in rat brain.

Application of genomics to drug design: the example of the histamine H3 receptor

The histamine H(3) receptor was characterized in the 1980s as an autoreceptor regulating histamine release in brain. Since then, selective drugs have been designed, many of them displaying a high potency in vivo, and used in many studies to delineate the implications of cerebral histaminergic systems in physiological functions such as arousal or cognitive functions. The recent cloning of the H(3) receptor, more than 15 years later, has allowed to start molecular studies that led to important findings for optimization of drug design. In agreement some ligands display distinct affinities for the recombinant rat and human H(3) receptors, a difference that we assign to two amino acids in the third transmembrane domain. In addition, H(3) autoreceptors present in the brain display high constitutive activity including in vivo. As a consequence, inverse agonists enhance histamine neuron activity and constitute a novel potential therapeutic approach to schizophrenia and Alzheimer's disease.

Chromosomal mapping and organization of the human histamine H3 receptor gene

The histamine H3 receptor (H3R) was recently cloned, and two isoforms, termed H3L and H3S, differing in the third intracytosolic loop, were isolated but the chromosomal mapping and organization of its gene remained unknown. PCR analysis of a human x rodent cell hybrid panel indicated that the H3R gene is located in the telomeric region of chromosome 20q. Alignment of human H3R cDNA sequences with DNA sequences of this chromosome revealed that its coding region comprises three exons interrupted by two introns located in the second transmembrane domain (TM2) and second intracytosolic loop, respectively. Thus the organization of the H3R gene indicates that the H3L and H3S isoforms, that we characterized not only in rodents but also in humans, are generated by retention and deletion, respectively, of a pseudo-intron located in the third intracytosolic loop.

The rat H3 receptor: gene organization and multiple isoforms

Genomic DNA analysis revealed that the coding region of the rat histamine H3 receptor comprises three exons interrupted by two introns of approximately 1 kb each. Several H3 receptor mRNA variants were identified by PCR and cDNA cloning and sequencing. Four variants generated by pseudo-intron retention/deletion at the level of the third intracellular loop were designated H3(445), H3(413), H3(410), and H3(397), according to the length of their deduced amino acid sequence and display differential tissue expression. When expressed in CHO-K1 or Cos-1 cells, the H3(445), H3(413), and H3(397) were found to generate specific 125I iodoproxyfan binding of similar pharmacological profile. In addition, we identified two short variants, termed H3(nf1) and H3(nf2), which correspond to frame shift and stop codon interposition, respectively, and are presumably nonfunctional, among which H3(nf2) displays brain expression similar to that of the longer isoforms.

High constitutive activity of native H3 receptors regulates histamine neurons in brain

Some G-protein-coupled receptors display 'constitutive activity', that is, spontaneous activity in the absence of agonist. This means that a proportion of the receptor population spontaneously undergoes an allosteric transition, leading to a conformation that can bind G proteins. The process has been shown to occur with recombinant receptors expressed at high density, and/or mutated, but also non-mutated recombinant receptors expressed at physiological concentrations. Transgenic mice that express a constitutively active mutant of the beta2-adrenergic receptor display cardiac anomalies; and spontaneous receptor mutations leading to constitutive activity are at the origin of some human diseases. Nevertheless, this process has not previously been found to occur in animals expressing normal levels of receptor. Here we show that two isoforms of the recombinant rat H3 receptor display high constitutive activity. Using drugs that abrogate this activity ('inverse agonists') and a drug that opposes both agonists and inverse agonists ('neutral antagonist'), we show that constitutive activity of native H3 receptors is present in rodent brain and that it controls histaminergic neuron activity in vivo. Inverse agonists may therefore find therapeutic applications, even in the case of diseases involving non-mutated receptors expressed at normal levels.

Distinct pharmacology of rat and human histamine H(3) receptors: role of two amino acids in the third transmembrane domain

Starting from the sequence of the human histamine H(3) receptor (hH(3)R) cDNA, we have cloned the corresponding rat cDNA. Whereas the two deduced proteins show 93.5% overall homology and differ only by five amino acid residues at the level of the transmembrane domains (TMs), some ligands displayed distinct affinities. Thioperamide and ciproxifan were about 10 fold more potent at the rat than at the human receptor, whereas FUB 349 displayed a reverse preference. Histamine, (R)alpha-methylhistamine, proxyfan or clobenpropit were nearly equipotent at H(3) receptors of both species. The inverse discrimination patterns of ciproxifan and FUB 349 were partially changed by mutation of one amino acid (V122A), and fully abolished by mutation of two amino acids (A119T and V122A), in TM3 of the rH(3)R located in the vicinity of Asp(114) purported to salt-link the ammonium group of histamine. Therefore, these two residues appear to be responsible for the distinct pharmacology of the H(3)R in the two species.

Pancreatic inflammation, apoptosis, and growth: sequential events after partial pancreatectomy in pigs

Positive signs of pancreas regeneration were observed in rats after induced pancreatitis and partial pancreatectomy (1,2). Although the human pancreas did not regenerate after partial anatomic resection (3), the pig pancreas exhibited growth responses to bombesin after partial pancreatectomy (4). This study was undertaken to establish the time course of pancreatic inflammation, apoptosis, and hypertrophy and/or hyperplasia after partial pancreatectomy in pigs.

In vitro comparison of the use of two large-animal, centrally threaded, positive-profile transfixation pin designs in the equine third metacarpal bone

OBJECTIVE

To compare the in vitro holding power and associated microstructural damage of 2 large-animal centrally threaded positive-profile transfixation pins in the diaphysis of the equine third metacarpal bone.

SAMPLE POPULATION

25 pairs of adult equine cadaver metacarpal bones.

PROCEDURE

Centrally threaded positive-profile transfixation pins of 2 different designs (ie, self-drilling, self-tapping [SDST] vs nonself-drilling, nonself-tapping [NDNT] transfixation pins) were inserted into the middiaphysis of adult equine metacarpal bones. Temperature of the hardware was measured during each step of insertion with a surface thermocouple. Bone and cortical width, transfixation pin placement, and cortical damage were assessed radiographically. Resistance to axial extraction before and after cyclic loading was measured using a material testing system. Microstructural damage caused by transfixation pin insertion was evaluated by scanning electron microscopy.

RESULTS

The temperature following pin insertion was significantly higher for SDST transfixation pins. Periosteal surface cortical fractures were found in 50% of the bones with SDST transfixation pins and in none with NDNT transfixation pins. The NDNT transfixation pins were significantly more resistant to axial extraction than SDST transfixation pins. Grossly and microscopically, NDNT transfixation pins created less damage to the bone and a more consistent thread pattern.

CONCLUSIONS AND CLINICAL RELEVANCE

In vitro analysis revealed that insertion of NDNT transfixation pins cause less macroscopic and microscopic damage to the bone than SDST transfixation pins. The NDNT transfixation pins have a greater pull out strength, reflecting better initial bone transfixation pin stability.

Cloning and cerebral expression of the guinea pig histamine H3 receptor: evidence for two isoforms

We cloned the full length guinea pig H3 receptor cDNA using RT-PCR amplification with primers from the human receptor and templates from brain areas. Evidence was obtained for two isoforms, designated H3L and H3S, differing by a 30 amino acid stretch within the third cytosolic loop, presumably generated by alternative splicing. In situ hybridization using a selective cRNA probe showed the gene transcripts to be highly expressed in discrete neuronal populations, e.g. pyramidal cells in the cerebral cortex or cerebellar Purkinje cells, in some instances already known to express other histamine receptor subtypes.

Histamine H2 receptor gene variants: lack of association with schizophrenia

A role of histaminergic neuronal systems in schizophrenia was suggested by an association with several polymorphisms located in the coding region of the histamine H2-receptor (H2R) gene (Orange et al, Mol Psychiatry 1996; 1: 466-469). Using either the reference method of direct sequencing or restriction endonuclease digestion of PCR products amplified from DNA, we could not confirm the existence of these polymorphisms in 53 Swedish controls, 52 French controls and 88 French schizophrenics. In contrast, we detected a G543A transition in the coding region of the gene that was not found in the British population. This allelic variation, which was observed in 15% of the controls with no homozygotes, did not change the amino acid sequence of the receptor. We also analyzed a 1.8-kb nucleotide sequence of the promoter region in which we detected two additional polymorphisms that may modulate the expression of the H2R gene. The first one was a A-592G transition located in the minimal promoter of the gene and found in;10% of controls with no homozygotes. The second one was a G-1018A transition located in an enhancer element of the promoter and was found in;20-30% of controls (with;2-4% homozygotes). DNA analysis of the 88 French schizophrenic subjects revealed that the incidence of the three polymorphisms was not significantly different in this population. In conclusion, the present findings may suggest a surprisingly high variability of the H2R gene polymorphisms in different geographical areas but do not support an association of these allelic variations with schizophrenia.

Changes in histamine H3 receptor responsiveness in mouse brain

Changes in various histamine (HA) H3 receptor-mediated responses and H3 receptor binding in brain were investigated in mice receiving single or repeated administration of ciproxifan, a potent brain-penetrating and selective H3 receptor antagonist. Blockade of the H3 autoreceptor was nearly as effective in enhancing levels of tele-methylhistamine (t-MeHA), a major HA metabolite, in brain areas when ciproxifan was administered once either at 7 a.m. or 8 p.m., in spite of the large differences of basal levels at these two phases of the circadian cycle. Blockade after a single ciproxifan administration was, however, followed by a transient decrease in striatal t-MeHA levels, possibly reflecting rapid development of autoreceptor hypersensitivity. Following a 5-day administration of ciproxifan and a 2-day drug-free period, basal t-MeHA levels were significantly decreased (approximately -20%) in three brain areas, and the ED50 values of the drug to enhance t-MeHA levels were increased by 5-15 times without significant change in maximal response, indicating that H3 autoreceptor hypersensitivity had developed. However, in synaptosomes from the cerebral cortex of these animals, the H3 receptor-mediated inhibition of K+-induced [3H]HA release was not significantly modified. Subchronic administration of ciproxifan for 10 days also resulted in an increased binding of [125I]iodoproxyfan to the H3 receptor of striatal and hypothalamic membranes by 40-54%. Hypersensitivity at H3 somatodendritic autoreceptors and at heteroreceptors attributable to an increased number of HA binding sites could account for the various changes observed in this study.

High intraosseous pressure as a cause of lameness in a horse with a degloving injury of the metatarsus

A 6-year-old Paint mare undergoing treatment for a degloving injury of the right metatarsus developed a non-weight-bearing lameness 19 days after admission. Diagnostic nerve blocks localized the source of pain to the area between the tarsus and the metatarsophalangeal joint. Radiography of the metatarsus and metatarsophalangeal joint, arthrocentesis of the metatarsophalangeal joint, and ultrasonography of the flexor tendons, flexor tendon sheath, and suspensory ligament failed to identify the cause of the lameness. The horse was anesthetized and intraosseous pressure was measured in the left and right third metatarsal bones, using a self-tapping cannulated screw attached to a pressure transducer. Pressure in the affected limb (46 mm Hg) was 3.5 times as high as pressure in the unaffected limb (13 mm Hg). The day after pressures were measured and fenestration was performed, signs of lameness were substantially improved. High intraosseous pressure in the affected limb was most likely secondary to edema, inflammation, and partial venous thrombosis, in combination with bone neovascularization, that impaired intraosseous venous drainage from the medullary cavity. Fenestration of the affected bone relieved the excessive pressure and allowed for resolution of pain.