Incidence rate, predictors and outcomes of interruption of HIV care: nationwide results from the Belgian HIV cohort.

OBJECTIVES: We aimed to study the incidence rate, predictors and outcomes of HIV care interruption (HCI) in Belgium. METHODS: We analysed data for adult patients with at least two HIV care records in the Belgian HIV cohort between 1 January 2007 and 31 December 2016. An HCI episode was defined as 1 year without an HIV care record. The HCI incidence rate was analysed using Poisson regression, return to HIV care using a cumulative incidence function with death as a competing risk, and viral load (VL) status upon return to HIV care using logistic regression. RESULTS: We included 16 066 patients accounting for 78 625 person-years of follow-up. The incidence rate of HCI was 5.3/100 person-years [95% confidence interval (CI) 5.1-5.4/100 person-years]. The incidence of return to HIV care after HCI was estimated at 77.5% (95% CI 75.7-79.2%). Of those who returned to care, 43.7% had a VL ≤ 200 HIV-1 RNA copies/mL, suggesting care abroad or suboptimal care (without an HIV-related care record) in Belgium during the HCI, and 56.3% returned without controlled VL and were therefore considered as having experienced a real gap in HIV care; they represented 2.3/100 person-years of follow-up. Factors individually associated with HCI were no antiretroviral therapy (ART) uptake, lower age, injecting drug use, non-Belgian nationality, male gender, not being a man who has sex with men, a shorter time since HIV diagnosis, no high blood pressure and CD4 count < 350 cells/µL. CONCLUSIONS: This study highlights the need to investigate return to care and viral status at return, to better understand HCI. Identified predictors can help health care workers to target patients at higher risk of HCI for awareness and support.

Transmission of HIV Drug Resistance and the Predicted Effect on Current First-line Regimens in Europe.

BACKGROUND: Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001. METHODS: Demographic, clinical, and virological data from 4140 antiretroviral-naive human immunodeficiency virus (HIV)-infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002 to 2007. Baseline susceptibility to antiretroviral drugs was predicted using the Stanford HIVdb program version 7.0. RESULTS: The overall prevalence of TDR did not change significantly over time and was 8.3% (95% confidence interval, 7.2%-9.5%) in 2008-2010. The most frequent indicators of TDR were nucleoside reverse transcriptase inhibitor (NRTI) mutations (4.5%), followed by nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations (2.9%) and protease inhibitor mutations (2.0%). Baseline mutations were most predictive of reduced susceptibility to initial NNRTI-based regimens: 4.5% and 6.5% of patient isolates were predicted to have resistance to regimens containing efavirenz or rilpivirine, respectively, independent of current NRTI backbones. CONCLUSIONS: Although TDR was highest for NRTIs, the impact of baseline drug resistance patterns on susceptibility was largest for NNRTIs. The prevalence of TDR assessed by epidemiological surveys does not clearly indicate to what degree susceptibility to different drug classes is affected.

Late presentation to HIV testing is overestimated when based on the consensus definition.

OBJECTIVES: In 2011, a consensus was reached defining "late presenters" (LPs) as individuals presenting for care with a CD4 count < 350 cells/µL or with an AIDS-defining event, regardless of CD4 count. However, a transient low CD4 count is not uncommon in recent infections. The objective of this study was to investigate how measurements of late presentation change if the clinical stage at the time of diagnosis is taken into account. METHODS: Case surveillance data for newly diagnosed patients in Belgium in 1998-2012 were analysed, including CD4 count at diagnosis, the presence of AIDS-defining events, and recent infections (< 6 months) as reported by clinicians in the case of acute illness or a recent negative test. First, proportions of LPs were calculated according to the consensus definition. Secondly, LPs were reclassified as "nonlate" if infections were reported as recent. RESULTS: A total of 7949 HIV diagnoses were included in the study. Recent infections were increasingly reported over time, accounting for 8.2% of new infections in 1998 and 37.5% in 2012. The consideration of clinical stage significantly modified the proportion of LPs: 18.2% of men who have sex with men (MSM) diagnosed in 2012 would be classified as LPs instead of 30.9% using the consensus definition (P < 0.001). The proportion of patients misclassified as LPs increased significantly over time: 5% in MSM in 1998 vs. 41% in 2012. CONCLUSIONS: This study suggests that low CD4 counts in recent infections may lead to overestimation of late presentation when applying the consensus definition. The impact of transient CD4 count on late presentation estimates should be assessed and, if relevant, the introduction of clinical stage in the definition of late presentation should be considered.

Good continuum of HIV care in Belgium despite weaknesses in retention and linkage to care among migrants.

BACKGROUND: The Belgian HIV epidemic is largely concentrated among men who have sex with men and Sub-Saharan Africans. We studied the continuum of HIV care of those diagnosed with HIV living in Belgium and its associated factors. METHODS: Data on new HIV diagnoses 2007-2010 and HIV-infected patients in care in 2010-2011 were analysed. Proportions were estimated for each sequential stage of the continuum of HIV care and factors associated with attrition at each stage were studied. RESULTS: Of all HIV diagnosed patients living in Belgium in 2011, an estimated 98.2% were linked to HIV care, 90.8% were retained in care, 83.3% received antiretroviral therapy and 69.5% had an undetectable viral load (<50 copies/ml). After adjustment for sex, age at diagnosis, nationality and mode of transmission, we found lower entry into care in non-Belgians and after preoperative HIV diagnoses; lower retention in non-Belgians and injecting drug users; higher retention in men who have sex with men and among those on ART. Younger patients had lower antiretroviral therapy uptake and less viral suppression; those with longer time from diagnosis had higher ART uptake and more viral suppression; Sub-Saharan Africans on ART had slightly less viral suppression. CONCLUSIONS: The continuum of HIV care in Belgium presents low attrition rates over all stages. The undiagnosed HIV-infected population, although not precisely estimated, but probably close to 20% based on available survey and surveillance results, could be the weakest stage of the continuum of HIV care. Its identification is a priority along with improving the HIV care continuum of migrants.

Benefit of inhalation aromatherapy as a complementary treatment for stress and anxiety in a clinical setting - A systematic review.

OBJECTIVE: The purpose of this systematic review is to ascertain the impact of inhalation aromatherapy on stress and anxiety in clinical settings. METHODS: A search strategy was developed using various databases. Randomised Controlled Trials (RCTs) as well as single and double-blind pilot clinical studies (non-RCT) using inhalation aromatherapy with an essential oil blend or a single essential oil were examined. All studies included a control intervention and use of a validated measurement tool. The time period under review was years 2000-2021. Due to the high level of heterogeneity and element of bias, a narrative synthesis was conducted. RESULTS: The search strategy initially retrieved 628 studies and through application of the selection criteria and the removal of duplicates, 76 studies were selected for review with a total of 6539 patients. In 42% of the RCTs, physiological measures including vital signs and/or salivary cortisol were used in addition to questionnaires. Over 70% of the studies reported a positive effect on anxiety levels in the aromatherapy intervention groups compared with the control. However, in many cases this is limited by the absence of safety data, imprecise reporting of plant species and dosage of essential oil. CONCLUSION: Inhalation aromatherapy has the potential to reduce stress and anxiety with data emerging to further support this result across a wide modality of clinical treatments. However, there is a clear need for the development of standard protocols for research in this area, generating measurable results which will create the opportunity for more rigorous evidence-based outcomes.

Retinal astrocytomas: long-term follow-up.

BACKGROUND: Retinal astrocytomas are exceedingly rare benign tumours of the retina. Their occurrence can be solitary or multiple, uni- or bilateral, isolated or in association with a phakomatosis such as tuberous sclerosis or neurofibromatosis type 1. PATIENTS AND METHODS: We report the long-term follow-up in three patients with retinal astrocytomas. RESULTS: Over many years of follow-up all astrocytomas showed very little progression and no deterioration of visual function. Subtle changes occurred inside the lesions. CONCLUSIONS: Even after long-term follow-up the natural course of retinal astrocytic hamartomas seems to be favourable, with visual loss and significant growth being unlikely to occur. A thorough ophthalmological and general evaluation, in order to rule out an underlying systemic disease and to document the ocular status, are needed initially. Thereafter eye examinations can be scheduled in long intervals.

HIV infections and STI co-infections in men who have sex with men in Belgium: sustained increase in HIV diagnoses.

Belgium is currently experiencing an upward trend in the number of new HIV diagnoses characterised by a continuous increase in the number of cases among men who have sex with men (MSM). Based on surveillance data, in the past decade the yearly number of newly diagnosed HIV cases in MSM increased more than threefold, from 101 cases diagnosed in 1999 to 332 cases in 2008. During this period, the majority of new HIV infections in MSM were diagnosed among Belgian citizens (72%), followed by other European nationalities (13%). The increase in HIV diagnoses does not reflect an increase in HIV testing since the number of tests performed nationwide remained remarkably stable over time. The steady increase in the number of newly diagnosed HIV cases among MSM, and the high proportion of MSM among HIV-positive patients co-infected with other sexually transmitted infections (STI) (95.6% in 2008) indicate increases in unsafe sex practices in this group. Development of behavioural surveillance and more qualitative research on reasons for unsafe sex are needed in order to develop more effective prevention strategies.

Lymphogranuloma venereum in Europe, 2003-2008.

Lymphogranuloma venereum, caused by the L serovars of Chlamydia trachomatis, emerged in Europe in 2003 and a series of outbreaks were reported in different countries. The infection presents as a severe proctitis in men who have sex with men, many of whom are co-infected with HIV and other sexually transmitted infections. This paper reviews the number of cases reported over a five year period, from 2003 to 2008, from countries that were part of the European Surveillance of Sexually Transmitted Infections (ESSTI) network. Reports were received from Belgium, Denmark, France, Germany, the Netherlands, Portugal, Spain, Sweden, and the United Kingdom. It appears that after five years the characteristics of the patients infected has overall remained unchanged, although the total number of cases has increased and more countries in Europe have now identified cases of LGV.

[Incidence of Neisseria gonorrhoeae infections in Belgium: trends 2000-2006]. / Incidence des infections à Neisseria gonorrhoeae en Belgique: tendances 2000-2006.

In Belgium, three registration systems collect epidemiological information on N. gonorrhoeae infections. The descriptive analysis of the data presented in this article allows describing the epidemiology of N. gonorrhoeae infections in Belgium in terms of trends in time, describing the characteristics of the patients, and providing information on resistance to antibiotics. The results on the incidence of N. gonorrhoeae infections show an important increase since the year 2000, and this increase is even more pronounced between 2005 and 2006. The majority of the patients reside in big cities, mainly in the district of Antwerp and in the Brussels-Capital region. Among the N. gonorrhoeae specimens that were sent to the reference laboratory, the proportion of specimens resistant to ciprofloxacine increases each year; this proportion reaches 61.4% in 2006. The increase in the incidence of N. gonorrhoeae infections and in antimicrobial resistance is also observed in other European countries. The increase in incidence may be partly related to the important increase of resistance to ciprofloxacine. It is very important to continue the surveillance of antimicrobial resistance, to adapt treatment in function of the recent evolutions and to inform physicians at a regular basis. The results show that homo- and bisexual men are most at risk for N. gonorrhoeae infections. The prevention campaigns for sexually transmitted infections and screening policy have to be reinforced, particularly among homo- and bisexual men.

Chemoimmunotherapy versus chemotherapy for metastatic malignant melanoma.

BACKGROUND: Malignant melanoma, one of the most aggressive of all skin cancers, is increasing in incidence throughout the world. Surgery remains the cornerstone of curative treatment in earlier stages. Metastatic disease is incurable in most affected people, because melanoma does not respond to most systemic treatments. A number of novel approaches are under evaluation and have shown promising results, but they are usually associated with increased toxicity and cost. The combination of chemotherapy and immunotherapy has been reported to improve treatment results, but it is still unclear whether evidence exists to support this choice, compared with chemotherapy alone. No language restrictions were imposed. OBJECTIVES: To compare the effects of therapy with chemotherapy and immunotherapy (chemoimmunotherapy) versus chemotherapy alone in people with metastatic malignant melanoma. SEARCH STRATEGY: We searched the Cochrane Skin Group Specialised Register (14 February 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2005), MEDLINE (2003 to 30 January 2006 ), EMBASE (2003 to 20 July 2005) and LILACS (1982 to 20 February 2006). References, conference proceedings, and databases of ongoing trials were also used to locate trials. SELECTION CRITERIA: All randomised controlled trials that compared the use of chemotherapy versus chemoimmunotherapy on people of any age, diagnosed with metastatic melanoma. DATA COLLECTION AND ANALYSIS: Two authors independently assessed each study to determine whether it met the pre-defined selection criteria, with differences being resolved through discussion with the review team. Two authors independently extracted the data from the articles using data extraction forms. Quality assessment included an evaluation of various components associated with biased estimates of treatment effect. Whenever possible, a meta-analysis was performed on the extracted data, in order to calculate a weighed treatment effect across trials. MAIN RESULTS: Eighteen studies met our criteria and were included in the meta-analysis, with a total of 2625 participants. We found evidence of an increase of objective response rates in people treated with chemoimmunotherapy, in comparison with people treated with chemotherapy. Nevertheless, the impact of these increased response rates was not translated into a survival benefit. We found no difference in survival to support the addition of immunotherapy to chemotherapy in the systemic treatment of metastatic melanoma, with a hazard ratio of 0.89 (95% CI 0.72 to 1.11, p=0.31). Additionally, we found increased hematological and non-hematological toxicities in people treated with chemoimmunotherapy. AUTHORS' CONCLUSIONS: We failed to find any clear evidence that the addition of immunotherapy to chemotherapy increases survival of people with metastatic melanoma. Further use of combined immunotherapy and chemotherapy should only be done in the context of clinical trials.

High HIV prevalence among patients choosing anonymous and free testing in Belgium, 1990-2002.

From 1990 through 2002, 25,250 anonymous and free HIV tests were performed at a testing site, which carried out the majority (85%) of anonymous testing in Belgium. During the same period, approximately 7.3 million confidential tests were registered nationwide. The rate of new HIV infections diagnosed at the anonymous testing site was 11.1/1000 tests; it was significantly higher than the rate observed among confidential tests (relative risk = 7.41; P < 0.0001). New HIV cases diagnosed through anonymous testing include a higher proportion of young adults (42.0% versus 32.5% in confidential testing; P < 0.001) and a higher proportion of men who have sex with men (32.7% vs. 25.9% in confidential testing; P < 0.02). Anonymous and free HIV testing was particularly sought by persons with higher infection risk, and efficiently contributed to HIV diagnosis in this population. Anonymous and free testing should be and remain an accessible alternative integrated in HIV testing policies.

Myocardial viability assessment by endocardial electroanatomic mapping: comparison with metabolic imaging and functional recovery after coronary revascularization.

OBJECTIVES: The objective of this study was to compare electroanatomic mapping for the assessment of myocardial viability with nuclear metabolic imaging using positron emission computed tomography (PET) and with data on functional recovery after successful myocardial revascularization. BACKGROUND: Animal experiments and first clinical studies suggested that electroanatomic endocardial mapping identifies the presence and absence of myocardial viability. METHODS: Forty-six patients with prior (> or =2 weeks) myocardial infarction underwent fluorine-18 fluorodeoxyglucose (FDG) PET and Tc-99m sestamibi single-photon emission computed tomography (SPECT) before mapping and percutaneous coronary revascularization. The left ventricular endocardium was mapped and divided into 12 regions, which were assigned to corresponding nuclear regions. Functional recovery using the centerline method was assessed in 25 patients with a follow-up angiography. RESULTS: Regional unipolar electrogram amplitude was 11.0 mV +/- 3.6 mV in regions with normal perfusion, 9.0 mV +/- 2.8 mV in regions with reduced perfusion and preserved FDG-uptake and 6.5 mV +/- 2.6 mV in scar regions (p < 0.001 for all comparisons). At a threshold amplitude of 7.5 mV, the sensitivity and specificity for detecting viable (by PET/SPECT) myocardium were 77% and 75%, respectively. In infarct areas with electrogram amplitudes >7.5 mV, improvement of regional wall motion (RWM) from -2.4 SD/chord +/- 1.0 SD/chord to -1.5 SD/chord +/- 1.1 SD/chord (p < 0.01) was observed, whereas, in infarct areas with amplitudes <7.5 mV, RWM remained unchanged at follow-up (-2.3 SD/chord +/- 0.7 SD/chord to -2.4 SD/chord +/- 0.7 SD/chord). CONCLUSIONS: These data suggest that the regional unipolar electrogram amplitude is a marker for myocardial viability and that electroanatomic mapping can be used for viability assessment in the catheterization laboratory.

Colony stimulating factors for prevention of myelosupressive therapy induced febrile neutropenia in children with acute lymphoblastic leukaemia.

BACKGROUND: Acute lymphoblastic leukaemia (ALL) is the most common cancer in childhood and febrile neutropenia is a potentially life-threatening side effect of its treatment. Current treatment consists of supportive care plus antibiotics. Clinical trials have attempted to evaluate the use of colony-stimulating factors (CSF) as additional therapy to prevent febrile neutropenia in children with ALL. The individual trials do not show whether there is significant benefit or not. Systematic review provides the most reliable assessment and the best recommendations for practice. OBJECTIVES: To evaluate the safety and effectiveness of the addition of G-CSF or GM-CSF to myelosuppressive chemotherapy in children with ALL, in an effort to prevent the development of febrile neutropenia. Evaluation of number of febrile neutropenia episodes, length to neutrophil count recovery, incidence and length of hospitalisation, number of infectious disease episodes, incidence and length of treatment delays, side effects (flu-like syndrome, bone pain and allergic reaction), relapse and overall mortality (death). SEARCH STRATEGY: The search covered the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CANCERLIT, LILACS, and SciElo. We manually searched records of conference proceedings of ASCO and ASH from 1985 to 2003 as well as databases of ongoing trials. We consulted experts and scanned references from the relevant articles. SELECTION CRITERIA: We looked for randomised controlled trials (RCTs) comparing CSF with placebo or no treatment as primary or secondary prophylaxis to prevent febrile neutropenia in children with ALL. DATA COLLECTION AND ANALYSIS: Two authors independently selected, critically appraised studies and extracted relevant data. The end points of interest were:* Primary end points: number of febrile neutropenia episodes and overall mortality (death) * Secondary end points: time to neutrophil count recovery, incidence and length of hospitalisation, number of infectious diseases episodes, incidence and length of treatment delays, side effects (flu-like syndrome, bone pain and allergic reaction) and relapse. We conducted a meta-analysis of these end points and expressed the results as Peto odds ratios. For continuous outcomes we calculated a weighted mean difference and a standardised mean difference. For count data, meta-analysis of the logarithms of the rate ratios using generic inverse variance was employed. MAIN RESULTS: We scanned more than 5500 citations and included six studies with a total of 332 participants in the analysis. There were insufficient data to assess the effect on survival. The use of CSF significantly reduced the number of episodes of febrile neutropenia episodes (Rate Ratio = 0.63; 95% confidence interval (CI) 0.46 to 0.85; p =0.003, with substantial heterogeneity), the length of hospitalisation (weighted mean difference (WMD) = -1.58; 95% CI -3.00 to -0.15; p = 0.03), and number of infectious diseases episodes (Rate Ratio=0.44; 95%CI 0.24 to 0.80; p=0.002). In spite of these results, CSF did not influence the length of episodes of neutropenia (WMD = -1.11; 95% CI -3.55 to 1.32; p = 0.4) or delays in chemotherapy courses (Rate Ratio=0.77; 95%CI 0.49 to 1,23; p=0.28) . AUTHORS' CONCLUSIONS: Children with ALL treated with CSF benefit from shorter hospitalisation and fewer infections. However, there was no evidence for a shortened duration of neutropenia nor fewer treatment delays, and no useful information about survival. The role of CSF regarding febrile neutropenia episodes is still uncertain. Although current data shows statistical benefit for CSF use, substantial heterogeneity between included trials does not allow this conclusion.

Corticotropin-releasing factor (CRF) agonists stimulate testosterone production in mouse leydig cells through CRF receptor-1.

The influence of CRF on testosterone production in primary mouse Leydig cell cultures was studied, and the type of CRF receptor (CRF-R) involved in this activity was determined. CRF directly stimulated testosterone production in mouse Leydig cells, but did not influence the maximum human (h)CG-induced testosterone production. The effect was time- and dose-dependent, saturable with an EC50 of 2.84 nM for hCRF, antagonized by the CRF antagonist alpha-helical CRF9-41, and accompanied by intracellular cAMP elevation. The rank order of potency of the natural CRF agonists, hCRF, ovine CRF, sauvagine, and urotensin, corresponded to that of their activities on CRF-R1 in rat pituitary cells and also to that reported for this receptor, but not for CRF-R2, when transfected into various cell lines. Furthermore, the difference in response of mouse Leydig cells to [11-D-Thr,12-D-Phe]- and [13-D-His,14-D-Leu]-ovine CRF corresponded to that measured when COS cells expressing CRF-R1 were activated, but was considerably smaller than that observed for activation of COS cells expressing CRF-R2alpha or -R2beta. The messenger RNA encoding the mouse CRF-R1 was detected by RT-PCR in mouse Leydig cell preparations. In contrast to mouse Leydig cells, CRF agonists had no influence on the basal testosterone and cAMP production by rat Leydig cells, nor did the agonists or antagonist change the hCG-stimulated testosterone and cAMP production by these cells. It is concluded that mouse Leydig cells express CRF-R1, mediating elevation of testosterone production by CRF agonists through cAMP. Because potencies of CRF agonists in activating mouse Leydig cells were more than 10-fold lower compared with their potencies in stimulating rat pituitary cells, it is suggested that the coupling of the CRF-R1 to intracellular signaling in Leydig cells is different from that in corticotropic pituitary cells, at least in quantitative terms.

Novel partial agonists for the histamine H(3) receptor with high in vitro and in vivo activity.

Novel branched N-alkylcarbamates and aliphatic ethers derived from 3-(1H-imidazol-4-yl)propanol were prepared. The compounds were investigated on two functional histamine H(3)-receptor assays. Some compounds displayed partial agonist activity on synaptosomes of rat brain cortex but behaved as pure competitive antagonists on the guinea pig ileum. Under in vivo conditions after po application to mice, some of the compounds showed partial or full agonist activity. Highest in vivo potency was found for the 3,3-dimethylbutyl ether 10 (ED(50) = 0.29 mg/kg, full intrinsic activity). These novel agonists are structurally diverse from classical aminergic histamine H(3)-receptor agonists (e.g., (R)-alpha-methylhistamine, imetit) as they lack a basic moiety in the side chain, which is supposed to be important for the activation of the receptor protein. The selectivity for the histamine H(3) receptor was proven by determination of H(1)- and H(2)-receptor activity on functional assays of the guinea pig.

Development of chiral N-alkylcarbamates as new leads for potent and selective H3-receptor antagonists: synthesis, capillary electrophoresis, and in vitro and oral in vivo activity.

Novel carbamates as derivatives of 3-(1H-imidazol-4-yl)propanol with an N-alkyl chain were prepared as histamine H3-receptor antagonists. Branching of the N-alkyl side chain with methyl groups led to chiral compounds which were synthesized stereospecifically by a Mitsunobu protocol adapted Gabriel synthesis. The optical purity of some of the chiral compounds was determined (ee > 95%) by capillary electrophoresis (CE). The investigated compounds showed pronounced to high antagonist activity (Ki values of 4.1-316 nM) in a functional test for histamine H3 receptors on rat cerebral cortex synaptosomes. Similar H3-receptor antagonist activities were observed in a peripheral model on guinea pig ileum. No stereoselective discrimination for the H3 receptor for the chiral antagonists was found with the in vitro assays. All compounds were also screened for central H3-receptor antagonist activity in vivo in mice after po administration. Most compounds were potent agents of the H3-receptor-mediated enhancement of brain Ntau-methylhistamine levels. The enantiomers of the N-2-heptylcarbamate showed a stereoselective differentiation in their pharmacological effect in vivo (ED50 of 0.39 mg/kg for the (S)-derivative vs 1.5 mg/kg for the (R)-derivative) most probably caused by differences in pharmacokinetic parameters. H1- and H2-receptor activities were determined for some of the novel carbamates, demonstrating that they have a highly selective action at the histamine H3 receptor.

New histamine H(3)-receptor ligands of the proxifan series: imoproxifan and other selective antagonists with high oral in vivo potency.

Histamine H(3)-receptor antagonists of the proxifan series are described. The novel compounds possess a 4-(3-(phenoxy)propyl)-1H-imidazole structure and various functional groups, e.g., an oxime moiety, on the phenyl ring. Synthesis of the novel compounds and X-ray crystallography of one highly potent oxime derivative, named imoproxifan (4-(3-(1H-imidazol-4-yl)propyloxy)phenylethanone oxime), are described. Most of the title compounds possess high antagonist potency in histamine H(3)-receptor assays in vitro as well as in vivo in mouse CNS following po administration. Structure-activity relationships are discussed. Imoproxifan displays subnanomolar potency on a functional assay on synaptosomes of rat cerebral cortex (K(i) = 0.26 nM). In vivo, imoproxifan increases the central N(tau)-methylhistamine level with an ED(50) of 0.034 mg/kg po. A receptor profile on several functional in vitro assays was determined for imoproxifan, demonstrating high selectivity toward the histamine H(3) receptor for this promising candidate for further development.

Novel histamine H(3)-receptor antagonists and partial agonists with a non-aminergic structure.

We determined the affinities of eight novel histamine H(3)-receptor ligands (ethers and carbamates) for H(3)-receptor binding sites and their agonistic/antagonistic effects in two functional H(3)-receptor models. The compounds differ from histamine in that the ethylamine chain is replaced by a propyloxy chain; in the three ethers mentioned below (FUB 335, 373 and 407), R is n-pentyl, 3-methylbutyl and 3,3-dimethylbutyl, respectively. The compounds monophasically inhibited [(3)H]-N(alpha)-methylhistamine binding to mouse cerebral cortex membranes (pK(i) 7.51 - 9.53). The concentration-response curve of histamine for its inhibitory effect on the electrically evoked [(3)H]-noradrenaline overflow from mouse cortex slices was shifted to the right by these compounds (apparent pA(2) 6.61 - 8.00). Only FUB 373 and 407 inhibited the evoked overflow by themselves (intrinsic activities 0.3 and 0.4); these effects were counteracted by the H(3)-receptor antagonist clobenpropit. [(35)S]-GTPgammaS binding to mouse cortex membranes was stimulated by the H(3)-receptor agonist (R)-alpha-methylhistamine in a manner sensitive to clobenpropit. Among the novel compounds only FUB 373 and 407 stimulated [(35)S]-GTPgammaS binding (intrinsic activities 0.6 and 0.4). In conclusion, the novel compounds are partial H(3)-receptor agonists (FUB 373 and 407) or H(3)-receptor antagonists; comparison with FUB 335 shows that the transition from antagonist to agonist is caused by a slight structural change. A protonated N atom in the side chain is not necessary for agonism at H(3) receptors, proposing a receptor-ligand interaction different from that of classical agonists.

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.

Tissue-specific regulation of IRS-1 in unilaterally nephrectomized rats.

Insulin stimulates the tyrosine kinase activity of its receptor, resulting in the phosphorylation of its cytosolic substrate, insulin receptor substrate 1 (IRS-1). IRS-1 is also a substrate for different peptides and growth factors, and a transgenic mouse "knockout" for this protein does not have normal growth. However, the role of IRS-1 in kidney hypertrophy and/or hyperplasia was not investigated. In the present study we investigated IRS-1 protein and tyrosine phosphorylation levels in the remnant kidney after unilateral nephrectomy (UNX) in 6-week-old male Wistar rats. After insulin stimulation the levels of insulin receptor and IRS-1 tyrosine phosphorylation were reduced to 79 +/- 5% (P < 0.005) and 58 +/- 6% (P < 0.0001), respectively, of the control (C) levels, in the remnant kidney. It is possible that a circulating factor and/or a local (paracrine) factor playing a role in kidney growth can influence the early steps of insulin action in parallel. To investigate the hypothesis of a circulating factor, we studied the early steps of insulin action in liver and muscle of unilateral nephrectomized rats. There was no change in pp185 tyrosine phosphorylation levels in liver (C 100 +/- 12% vs UNX 89 +/- 9%, NS) and muscle (C 100 +/- 22% vs UNX 91 +/- 17%, NS), and also there was no change in IRS-1 phosphorylation levels in both tissues. These data demonstrate that after unilateral nephrectomy there is a decrease in insulin-induced insulin receptor and IRS-1 tyrosine phosphorylation levels in kidney but not in liver and muscle. It will be of interest to investigate which factors, probably paracrine ones, regulate these early steps of insulin action in the contralateral kidney of unilaterally nephrectomized rats.