Comprehensive genomic features indicative for Notch responsiveness

Transcription factor RBPJ is the central component in Notch signal transduction and directly forms a coactivator complex together with the Notch intracellular domain (NICD). While RBPJ protein levels remain constant in most tissues, dynamic expression of Notch target genes varies depending on the given cell-type and the Notch activity state. To elucidate dynamic RBPJ binding genome-wide, we investigated RBPJ occupancy by ChIP-Seq. Surprisingly, only a small set of the total RBPJ sites show a dynamic binding behavior in response to Notch signaling. Compared to static RBPJ sites, dynamic sites differ in regard to their chromatin state, binding strength and enhancer positioning. Dynamic RBPJ sites are predominantly located distal to transcriptional start sites (TSSs), while most static sites are found in promoter-proximal regions. Importantly, gene responsiveness is preferentially associated with dynamic RBPJ binding sites and this static and dynamic binding behavior is repeatedly observed across different cell types and species. Based on the above findings we used a machine-learning algorithm to predict Notch responsiveness with high confidence in different cellular contexts. Our results strongly support the notion that the combination of binding strength and enhancer positioning are indicative of Notch responsiveness.

The structure, binding and function of a Notch transcription complex involving RBPJ and the epigenetic reader protein L3MBTL3

The Notch pathway transmits signals between neighboring cells to elicit downstream transcriptional programs. Notch is a major regulator of cell fate specification, proliferation, and apoptosis, such that aberrant signaling leads to a pleiotropy of human diseases, including developmental disorders and cancers. The pathway signals through the transcription factor CSL (RBPJ in mammals), which forms an activation complex with the intracellular domain of the Notch receptor and the coactivator Mastermind. CSL can also function as a transcriptional repressor by forming complexes with one of several different corepressor proteins, such as FHL1 or SHARP in mammals and Hairless in Drosophila. Recently, we identified L3MBTL3 as a bona fide RBPJ-binding corepressor that recruits the repressive lysine demethylase LSD1/KDM1A to Notch target genes. Here, we define the RBPJ-interacting domain of L3MBTL3 and report the 2.06 Å crystal structure of the RBPJ-L3MBTL3-DNA complex. The structure reveals that L3MBTL3 interacts with RBPJ via an unusual binding motif compared to other RBPJ binding partners, which we comprehensively analyze with a series of structure-based mutants. We also show that these disruptive mutations affect RBPJ and L3MBTL3 function in cells, providing further insights into Notch mediated transcriptional regulation.

Notch-dependent and -independent functions of transcription factor RBPJ

Signal transduction pathways often involve transcription factors that promote activation of defined target gene sets. The transcription factor RBPJ is the central player in Notch signaling and either forms an activator complex with the Notch intracellular domain (NICD) or a repressor complex with corepressors like KYOT2/FHL1. The balance between these two antagonizing RBPJ-complexes depends on the activation state of the Notch receptor regulated by cell-to-cell interaction, ligand binding and proteolytic cleavage events. Here, we depleted RBPJ in mature T-cells lacking active Notch signaling and performed RNA-Seq, ChIP-Seq and ATAC-seq analyses. RBPJ depletion leads to upregulation of many Notch target genes. Ectopic expression of NICD1 activates several Notch target genes and enhances RBPJ occupancy. Based on gene expression changes and RBPJ occupancy we define four different clusters, either RBPJ- and/or Notch-regulated genes. Importantly, we identify early (Hes1 and Hey1) and late Notch-responsive genes (IL2ra). Similarly, to RBPJ depletion, interfering with transcriptional repression by squelching with cofactor KYOT2/FHL1, leads to upregulation of Notch target genes. Taken together, RBPJ is not only an essential part of the Notch co-activator complex but also functions as a repressor in a Notch-independent manner.

Hydroxylation of the NOTCH1 intracellular domain regulates Notch signaling dynamics

Notch signaling plays a pivotal role in the development and, when dysregulated, it contributes to tumorigenesis. The amplitude and duration of the Notch response depend on the posttranslational modifications (PTMs) of the activated NOTCH receptor - the NOTCH intracellular domain (NICD). In normoxic conditions, the hydroxylase FIH (factor inhibiting HIF) catalyzes the hydroxylation of two asparagine residues of the NICD. Here, we investigate how Notch-dependent gene transcription is regulated by hypoxia in progenitor T cells. We show that the majority of Notch target genes are downregulated upon hypoxia. Using a hydroxyl-specific NOTCH1 antibody we demonstrate that FIH-mediated NICD1 hydroxylation is reduced upon hypoxia or treatment with the hydroxylase inhibitor dimethyloxalylglycine (DMOG). We find that a hydroxylation-resistant NICD1 mutant is functionally impaired and more ubiquitinated. Interestingly, we also observe that the NICD1-deubiquitinating enzyme USP10 is downregulated upon hypoxia. Moreover, the interaction between the hydroxylation-defective NICD1 mutant and USP10 is significantly reduced compared to the NICD1 wild-type counterpart. Together, our data suggest that FIH hydroxylates NICD1 in normoxic conditions, leading to the recruitment of USP10 and subsequent NICD1 deubiquitination and stabilization. In hypoxia, this regulatory loop is disrupted, causing a dampened Notch response.

SUMOylated non-canonical polycomb PRC1.6 complex as a prerequisite for recruitment of transcription factor RBPJ

BACKGROUND

Notch signaling controls cell fate decisions in many contexts during development and adult stem cell homeostasis and, when dysregulated, leads to carcinogenesis. The central transcription factor RBPJ assembles the Notch coactivator complex in the presence of Notch signaling, and represses Notch target gene expression in its absence.

RESULTS

We identified L3MBTL2 and additional members of the non-canonical polycomb repressive PRC1.6 complex in DNA-bound RBPJ associated complexes and demonstrate that L3MBTL2 directly interacts with RBPJ. Depletion of RBPJ does not affect occupancy of PRC1.6 components at Notch target genes. Conversely, absence of L3MBTL2 reduces RBPJ occupancy at enhancers of Notch target genes. Since L3MBTL2 and additional members of the PRC1.6 are known to be SUMOylated, we investigated whether RBPJ uses SUMO-moieties as contact points. Indeed, we found that RBPJ binds to SUMO2/3 and that this interaction depends on a defined SUMO-interaction motif. Furthermore, we show that pharmacological inhibition of SUMOylation reduces RBPJ occupancy at Notch target genes.

CONCLUSIONS

We propose that the PRC1.6 complex and its conjugated SUMO-modifications provide a favorable environment for binding of RBPJ to Notch target genes.

HDAC3 functions as a positive regulator in Notch signal transduction

Aberrant Notch signaling plays a pivotal role in T-cell acute lymphoblastic leukemia (T-ALL) and chronic lymphocytic leukemia (CLL). Amplitude and duration of the Notch response is controlled by ubiquitin-dependent proteasomal degradation of the Notch1 intracellular domain (NICD1), a hallmark of the leukemogenic process. Here, we show that HDAC3 controls NICD1 acetylation levels directly affecting NICD1 protein stability. Either genetic loss-of-function of HDAC3 or nanomolar concentrations of HDAC inhibitor apicidin lead to downregulation of Notch target genes accompanied by a local reduction of histone acetylation. Importantly, an HDAC3-insensitive NICD1 mutant is more stable but biologically less active. Collectively, these data show a new HDAC3- and acetylation-dependent mechanism that may be exploited to treat Notch1-dependent leukemias.

Clinical, histomorphological and therapeutic features of the Van der Woude Syndrome: literature review and presentation of an unusual case

BACKGROUND

Van der Woude syndrome (VWS), an autosomal dominant condition associated with lower lip pits and/or cleft palate, is caused by mutations in the interferon regulatory factor 6 gene (lRF6 gene). The genetic alterations identified to date that contribute to expression of the syndrome are chiefly mutations located on chromosome 1 (the largest of our chromosomes), mutations at p36 that codifies the gene GRHL (grainy-head transcriptor factor) and mutations involving IRF6 (interferon regulatory factor). With frequency ranging from 1:35,000 to 1:100,000, depending on ethnicity, gender, and socio-economic status, the syndrome accounts for about 2% of orofacial clefts. The clinical and histomorphological aspects of VWS are studied, and a case of heterozygous female twins of whom only one was affected with VWS is reported.

CONCLUSION

This very rare case (no similar case has been reported to date) contributes further evidence on modifying factors in the expression of this condition.

Histone variant H2A.Z deposition and acetylation directs the canonical Notch signaling response

A fundamental as yet incompletely understood feature of Notch signal transduction is a transcriptional shift from repression to activation that depends on chromatin regulation mediated by transcription factor RBP-J and associated cofactors. Incorporation of histone variants alter the functional properties of chromatin and are implicated in the regulation of gene expression. Here, we show that depletion of histone variant H2A.Z leads to upregulation of canonical Notch target genes and that the H2A.Z-chaperone TRRAP/p400/Tip60 complex physically associates with RBP-J at Notch-dependent enhancers. When targeted to RBP-J-bound enhancers, the acetyltransferase Tip60 acetylates H2A.Z and upregulates Notch target gene expression. Importantly, the Drosophila homologs of Tip60, p400 and H2A.Z modulate Notch signaling response and growth in vivo. Together, our data reveal that loading and acetylation of H2A.Z are required to assure tight control of canonical Notch activation.

Loss of the transcription factor RBPJ induces disease-promoting properties in brain pericytes

Sufficient vascular supply is indispensable for brain development and function, whereas dysfunctional blood vessels are associated with human diseases such as vascular malformations, stroke or neurodegeneration. Pericytes are capillary-associated mesenchymal cells that limit vascular permeability and protect the brain by preserving blood-brain barrier integrity. Loss of pericytes has been linked to neurodegenerative changes in genetically modified mice. Here, we report that postnatal inactivation of the Rbpj gene, encoding the transcription factor RBPJ, leads to alteration of cell identity markers in brain pericytes, increases local TGFβ signalling, and triggers profound changes in endothelial behaviour. These changes, which are not mimicked by pericyte ablation, imperil vascular stability and induce the acquisition of pathological landmarks associated with cerebral cavernous malformations. In adult mice, loss of Rbpj results in bigger stroke lesions upon ischemic insult. We propose that brain pericytes can acquire deleterious properties that actively enhance vascular lesion formation and promote pathogenic processes.

Pericytes are perivascular cells essential for blood-brain barrier maintenance. Here Diéguez-Hurtado et al. show that depletion of the transcription factor RBPJ in pericytes affects their molecular identity and disturbs endothelial cell behaviour, inducing the formation of vascular lesions in the brain.

The histone variant H2A.Z in gene regulation

The histone variant H2A.Z is involved in several processes such as transcriptional control, DNA repair, regulation of centromeric heterochromatin and, not surprisingly, is implicated in diseases such as cancer. Here, we review the recent developments on H2A.Z focusing on its role in transcriptional activation and repression. H2A.Z, as a replication-independent histone, has been studied in several model organisms and inducible mammalian model systems. Its loading machinery and several modifying enzymes have been recently identified, and some of the long-standing discrepancies in transcriptional activation and/or repression are about to be resolved. The buffering functions of H2A.Z, as supported by genome-wide localization and analyzed in several dynamic systems, are an excellent example of transcriptional control. Posttranslational modifications such as acetylation and ubiquitination of H2A.Z, as well as its specific binding partners, are in our view central players in the control of gene expression. Understanding the key-mechanisms in either turnover or stabilization of H2A.Z-containing nucleosomes as well as defining the H2A.Z interactome will pave the way for therapeutic applications in the future.

Cardiotoxicity during Chemotherapy for Advanced Gastroenteric Tumors

The authors report two cases of patients with advanced gastroenteric carcinoma, which developed different cardiotoxicity patterns after the administration of cytotoxic drugs. The firsts patient showed a picture of dilatative cardiomyopathy with associated symptoms of angina pectoris and congestive heart failure; the second patient presented a cardiac arrhythmia after several administrations of S-fluorouracil. The possible mechanisms of these toxic effects, as well as the drug interactions are briefly discussed. Cardiotoxicity of cytotoxic drugs should be considered by oncologists even in patients with no previous history of cardiac disease.

Abstract WP145: Depression in Stroke and TIA Survivors With Minimal or No Residual Deficits

Background: Depression after stroke can severely inhibit a patient’s recovery. While it affects roughly a third of all stroke survivors, there is a lack of literature evaluating depression in patients with minimal or no residual deficits.

Objectives: To evaluate variables associated with depression in patients with minimal or no residual deficits.

Methods: A retrospective analysis of patients with mild stroke, intracerebral hemorrhage (ICH) or TIA at our institution who presented to the stroke clinic from December 2016-July 2017 was conducted. A questionnaire gathering clinical and sociodemographic information, as well as levels of depression, was administered. Patients were assessed using the PHQ-2 and PHQ-9 depression scales. A Wilcoxon Ranked Sum test was used to analyze variables affecting depression. Statistical significance was set at 0.05.

Results: In total, 72 patients (58 ischemic, 5 ICH and 9 TIA) were identified. Approximately 4% (n=3) presented to clinic <6 weeks, 66.7% (n=48) 6-12 weeks, 23.6% (n=17) 12-24 weeks, and 5.6% (n=4) > 24 weeks from discharge. The median discharge NIH score was 1.5. Roughly 24% of patients (n=17) reported depression via the PHQ-9. Of these patients, 59% (n=10) reported depression prior to stroke and 41% (n=7) developed new depression. The median age was 62.5 years, 63.9% were female, and 70.8% Caucasian. Diabetic and unmarried patients reported significantly more depression ( p=0.005, 0.03) while patients attending occupational therapy were less depressed ( p=0.010 ). Age ( p=0.23 ), history of cancer ( p=0.95 ), prior stroke ( p=0.55 ), incontinence ( p=0. 27), stroke location (Right: p=0.72 ; Left: p=0.244 ), ability to return to work ( p=0.64 ), driving status ( p= 0.36), and discharge destination ( p=0. 09) did not significantly affect depression levels. Of the patients with no prior depression, 11.2% developed new depression after stroke.

Conclusion: In our study, a quarter of stroke and TIA patients with little to no residual deficits reported depression and roughly 1 in 10 reported new depressive symptoms. Depression is still a prevalent and concerning outcome that can have a major effect on a patient’s functional status. Further studies of depression in patients with minimal to no symptoms are needed.

Abstract TP155: Cognitive Impairment in Mild Stroke

Background: Cognitive symptoms are easily overlooked despite its effect on quality of life after stroke. In patients with minimal physical residual symptoms, the true burden of cognitive impairment is unknown.

Objective: To evaluate the risk factors and burden associated with cognitive impairment after mild stroke.

Methods: A retrospective observational cohort study of 56 patients (51 ischemic, 5 hemorrhagic) evaluated at the stroke clinic between July 2016 and June 2017 was performed. Patients completed a questionnaire including demographics and history including previously known cognitive impairment. Cognition was evaluated with the Montreal Cognitive Assessment Score (MOCA).

Results: The median age of the group studied was 61.5 years. Sixty-six percent (66.1%) patients were men and 76.8% Caucasian. The median discharge NIH score was 1. This study group did not have a previous diagnosis of dementia. About 4% (n=2) of patients presented to clinic <6 weeks, 71.4% (n=40) 6-12 weeks, 17.9% (n=10) 12-24weeks and 7.1% (n=4) >24 weeks from discharge. Cognitive assessment at the stroke clinic after discharge identified 19.6% patients with mild impairment, 16.1% with moderate impairment and 14.3% with dementia. MOCA scores were lower in those greater than 65 years of age ( p =0.022), living in facilities post-stroke ( p =0.007), have history of stroke and diabetes mellitus ( p =0.011, 0.019). Education level did not show significant difference in MOCA scores ( p =0.283). Those who were employed prior to their stroke have a higher MOCA score compared to those who were unemployed ( p =0.001). Of those previously working, 50% were able to return to work and this group had higher MOCA scores ( p =0.011). Of those who stopped driving, 19.6% was due to cognitive concerns.

Conclusion: In our study, about 50% of the mild stroke patients were found to have some degree of cognitive impairment. Factors that may suggest a higher risk for cognitive impairment after stroke include those age greater than 65, history of stroke and diabetes, unemployment and living in a facility. Post-stroke cognitive impairment was found to be associated with inability to return to work and drive. Since cognitive impairment can impact life quality, screening even in mild stroke could be beneficial.

Abstract WP286: Code Status Prior to Admission Dose Not Influence Timing of Transition to Inpatient Hospice in Devastating Stroke

Background: The transition of care from an aggressive disease-directed plan to comfort focused hospice care is a difficult choice for patients with devastating stroke and their family members particularly in the absence of advance directives. However, it is not clear if preexisting Do Not Resuscitate (DNR) status influences the timing of this decision.

Objectives: To evaluate factors associated with transfer time to hospice for patients with devastating stroke and, particularly, the influence of defined code status prior to admission.

Methods: A retrospective analysis of patients with stroke admitted to inpatient hospice from January 2013-December 2014 at our institution was conducted yielding 71 patients. The group was dichotomized to those with a preexisting DNR (n=19) or not (n=52). Clinical variables and sociodemographic factors were collected and compared using chi-square tests of proportion and t-tests for independent groups. Specifically, median time from admission to inpatient hospice for both groups was compared using a Wilcoxon Ranked Sum test set at 0.05 to test statistical significance.

Results: For all patients, the mean age was 82.01 +/- 9.64 years, 60.6% female and 84.5% Caucasian. Approximately 66% of strokes were ischemic and 34% hemorrhagic with a mean NIH score of 21.45 +/- 6.03. Age (83.7 +/- 9.8 vs. 81.4 +/- 9.6; p=0.377 ), ethnicity (% Caucasian: 84.2 vs. 84.6; p= 0.967 ), stroke subtype (% ischemic: 73.7 vs. 61.5; p= 0.343 ), severity (NIH: 21.2 +/- 8.8 vs. 20.9 +/- 4.6; p=0.852 ), insurance status (% Medicare Plus: 73.7 vs. 57.7; p=0.219 ), history of prior stroke (26.3% vs. 23.1%; p=0.777 ), dementia (21.1% vs. 28.9%; p=0.511 ), malignancy (10.53% vs. 13.46%; p=0.742 ), and living arrangement (% living with family: 73.7 vs. 51.9; p=0.132 ) were not statistically different in the DNR and no DNR cohorts respectively. The median time from admission to inpatient hospice for preexisting DNR vs. no DNR did not differ (3.0 vs. 4.5 days ; p=0.176 ).

Conclusion: In our study, there were no significant factors, including preexisting DNR status, that influenced transition time to inpatient hospice. Code status on admission is not an indicator of goals of care. Future studies are needed to validate these findings

Abstract TP151: Higher Than Expected Fatigue Among Mild Stroke and TIA Survivors

Background: A growing body of research indicates that fatigue is a common and debilitating sequel of both ischemic and hemorrhagic stroke affecting roughly half of all survivors. However, in patients with minimal to no residual symptoms (mild stroke and TIA) the prevalence and impact is unknown.

Objective: To evaluate the prevalence and functional impact of fatigue among patients with mild stroke and TIA.

Design/methods: A retrospective observational cohort questionnaire-based study from July 2016-July 2017 was conducted on patients presenting to stroke clinic for the first-time after hospital discharge and completed during the visit. A total of 72 patients (58 ischemic, 5 ICH and 9 TIA) were analyzed. Chart review of clinical data including demographics, stroke type, NIHSS, mRS, level of education, work status, living situation, vascular risk factors, and history of depression was completed. The Fatigue Assessment Scale (FAS) was utilized to determine level of fatigue. A score of 22 or higher indicated fatigue. Statistical significance was calculated using Pearson’s Chi-square and Fisher’s exact testing.

Result: Among all patients, median age was 62.5 years 64% were men and 70.8% Caucasian. The median discharge NIH score was 1.5 and 90% were evaluated within the first 12 weeks of hospital discharge. Approximately 42% of patients reported fatigue (n=30) and 19% (n=14) reported new fatigue since their event. Concomitant depression was observed in 45% of fatigued patients (n=13). Fatigue was most commonly observed among patients with an ischemic MCA territory infarction (p=.007). Patients with fatigue were less likely to drive a car (p=.04) and a trend towards being less likely to have returned to work was observed (p=.053).

Conclusions: A higher than expected proportion of patients with mild stroke or TIA report fatigue and roughly 1 in 5 reported new fatigue since their event despite only half of patients experiencing depression. Continued research is needed to better understand predictors of fatigue and its long term impact among these patients.

RBPJ/CBF1 interacts with L3MBTL3/MBT1 to promote repression of Notch signaling via histone demethylase KDM1A/LSD1

Notch signaling is an evolutionarily conserved signal transduction pathway that is essential for metazoan development. Upon ligand binding, the Notch intracellular domain (NOTCH ICD) translocates into the nucleus and forms a complex with the transcription factor RBPJ (also known as CBF1 or CSL) to activate expression of Notch target genes. In the absence of a Notch signal, RBPJ acts as a transcriptional repressor. Using a proteomic approach, we identified L3MBTL3 (also known as MBT1) as a novel RBPJ interactor. L3MBTL3 competes with NOTCH ICD for binding to RBPJ. In the absence of NOTCH ICD, RBPJ recruits L3MBTL3 and the histone demethylase KDM1A (also known as LSD1) to the enhancers of Notch target genes, leading to H3K4me2 demethylation and to transcriptional repression. Importantly, in vivo analyses of the homologs of RBPJ and L3MBTL3 in Drosophila melanogaster and Caenorhabditis elegans demonstrate that the functional link between RBPJ and L3MBTL3 is evolutionarily conserved, thus identifying L3MBTL3 as a universal modulator of Notch signaling in metazoans.

Chromatin Immunoprecipitation (ChIP) in Mouse T-cell Lines

Signaling pathways regulate gene expression programs via the modulation of the chromatin structure at different levels, such as by post-translational modifications (PTMs) of histone tails, the exchange of canonical histones with histone variants, and nucleosome eviction. Such regulation requires the binding of signal-sensitive transcription factors (TFs) that recruit chromatin-modifying enzymes at regulatory elements defined as enhancers. Understanding how signaling cascades regulate enhancer activity requires a comprehensive analysis of the binding of TFs, chromatin modifying enzymes, and the occupancy of specific histone marks and histone variants. Chromatin immunoprecipitation (ChIP) assays utilize highly specific antibodies to immunoprecipitate specific protein/DNA complexes. The subsequent analysis of the purified DNA allows for the identification the region occupied by the protein recognized by the antibody. This work describes a protocol to efficiently perform ChIP of histone proteins in a mature mouse T-cell line. The presented protocol allows for the performance of ChIP assays in a reasonable timeframe and with high reproducibility.

Tongue-tie assessment: clinical aspects and a new diode laser technique for its management

BACKGROUND Often breastfeeding problems experienced by mothers and their babies may be attributed to the abnormal attachment of the infant's tongue (ankyloglossia) and/or maxillary lip-tie. Proper breastfeeding depends upon an infant's ability to correctly latch onto its mother's breast. If born with oral soft tissue abnormalities such as tongue-tie or lip-tie, it may be almost impossible for the infant to breastfeed. During the oral evaluation of an infant presenting with breastfeeding problems, one factor that is often overlooked and undiagnosed - and thus untreated - is the attachment of the upper lip to the maxillary gingival tissue.

CASE REPORT

The case is reported of tongue-tie and breastfeeding difficulties, treated with a novel technique: the diode laser (980 nm).

A phospho-dependent mechanism involving NCoR and KMT2D controls a permissive chromatin state at Notch target genes

The transcriptional shift from repression to activation of target genes is crucial for the fidelity of Notch responses through incompletely understood mechanisms that likely involve chromatin-based control. To activate silenced genes, repressive chromatin marks are removed and active marks must be acquired. Histone H3 lysine-4 (H3K4) demethylases are key chromatin modifiers that establish the repressive chromatin state at Notch target genes. However, the counteracting histone methyltransferase required for the active chromatin state remained elusive. Here, we show that the RBP-J interacting factor SHARP is not only able to interact with the NCoR corepressor complex, but also with the H3K4 methyltransferase KMT2D coactivator complex. KMT2D and NCoR compete for the C-terminal SPOC-domain of SHARP. We reveal that the SPOC-domain exclusively binds to phosphorylated NCoR. The balance between NCoR and KMT2D binding is shifted upon mutating the phosphorylation sites of NCoR or upon inhibition of the NCoR kinase CK2β. Furthermore, we show that the homologs of SHARP and KMT2D in Drosophila also physically interact and control Notch-mediated functions in vivo. Together, our findings reveal how signaling can fine-tune a committed chromatin state by phosphorylation of a pivotal chromatin-modifier.

Mucocele of the minor salivary glands in an infant: treatment with diode laser

BACKGROUND

Mucoceles are benign lesions that develop as a result of retention or extravasation of mucous material from minor salivary glands. Very uncommon in newborns and infants, they rarely may interfere with breastfeeding and compromise the respiratory function.

CASE REPORT

We report a case of mucocele in a three-month-old infant in the right labial commissure excised by diode laser of different wavelengths (635-980 nm), with an average power of 1.8 W, in continuous wave mode, using 300 to 320 micron optical fibers. The healing occurred in 10 days. There were no adverse effects and the patient was carefully followed-up until complete healing.

CONCLUSION

T he diode laser is not only a valuable tool for mucocele eradication but it also reduces relapses, thanks to the characteristics of the laser light.

Site-specific methylation of Notch1 controls the amplitude and duration of the Notch1 response

Physiologically, Notch signal transduction plays a pivotal role in differentiation; pathologically, Notch signaling contributes to the development of cancer. Transcriptional activation of Notch target genes involves cleavage of the Notch receptor in response to ligand binding, production of the Notch intracellular domain (NICD), and NICD migration into the nucleus and assembly of a coactivator complex. Posttranslational modifications of the NICD are important for its transcriptional activity and protein turnover. Deregulation of Notch signaling and stabilizing mutations of Notch1 have been linked to leukemia development. We found that the methyltransferase CARM1 (coactivator-associated arginine methyltransferase 1; also known as PRMT4) methylated NICD at five conserved arginine residues within the C-terminal transactivation domain. CARM1 physically and functionally interacted with the NICD-coactivator complex and was found at gene enhancers in a Notch-dependent manner. Although a methylation-defective NICD mutant was biochemically more stable, this mutant was biologically less active as measured with Notch assays in embryos of Xenopus laevis and Danio rerio. Mathematical modeling indicated that full but short and transient Notch signaling required methylation of NICD.

Salivary α-amylase and cortisol after exercise in menopause: influence of long-term HRT

OBJECTIVES

This observational prospective study analyzed the effect of an incremental cardiopulmonary exercise test (CPET) on the secretion of salivary biomarkers of the adrenergic nervous system and hypothalamus-pituitary-adrenal (HPA) axis activity by measuring salivary α-amylase and cortisol diurnal trajectories in the setting of long-term hormone replacement therapy (HRT).

METHODS

Fifteen healthy sedentary postmenopausal women who were current HRT users and 15 women who had never used HRT were consecutively recruited. α-Amylase and cortisol were measured in salivary samples collected on the CPET day and on a rest day. Cardiovascular and respiratory fitness parameters were recorded during the CPET challenge.

RESULTS

The participants had very homogeneous somatic characteristics, and they were all in generally good health. The postmenopausal never-HRT users presented an abnormal diurnal pattern of α-amylase at baseline and a flattened response to CPET. In contrast, women on HRT had a physiological α-amylase diurnal pattern and increased salivary α-amylase production during the CPET-induced challenge. The CPET challenge physiologically activated the HPA axis activity, as shown by the increase in the concentration of salivary cortisol during the effort test. HPA axis activity was not affected by long-term HRT. Postmenopausal women using HRT exhibited a cardiorespiratory functional capacity that was significantly (p < 0.05) higher than that of non-users.

CONCLUSIONS

Our findings show that healthy postmenopausal women present an asymmetry between adrenergic nervous system and HPA axis activities under both basal and stress conditions. HRT was able to modify the abnormal adrenergic nervous system activity, most likely by reducing the sympathetic hyperactivity that characterizes menopause.

Interaction between catechol-O-methyltransferase (COMT) Val158Met genotype and genetic vulnerability to schizophrenia during explicit processing of aversive facial stimuli

BACKGROUND

Emotion dysregulation is a key feature of schizophrenia, a brain disorder strongly associated with genetic risk and aberrant dopamine signalling. Dopamine is inactivated by catechol-O-methyltransferase (COMT), whose gene contains a functional polymorphism (COMT Val158Met) associated with differential activity of the enzyme and with brain physiology of emotion processing. The aim of the present study was to investigate whether genetic risk for schizophrenia and COMT Val158Met genotype interact on brain activity during implicit and explicit emotion processing.

METHOD

A total of 25 patients with schizophrenia, 23 healthy siblings of patients and 24 comparison subjects genotyped for COMT Val158Met underwent functional magnetic resonance imaging during implicit and explicit processing of facial stimuli with negative emotional valence.

RESULTS

We found a main effect of diagnosis in the right amygdala, with decreased activity in patients and siblings compared with control subjects. Furthermore, a genotype × diagnosis interaction was found in the left middle frontal gyrus, such that the effect of genetic risk for schizophrenia was evident in the context of the Val/Val genotype only, i.e. the phenotype of reduced activity was present especially in Val/Val patients and siblings. Finally, a complete inversion of the COMT effect between patients and healthy subjects was found in the left striatum during explicit processing.

CONCLUSIONS

Overall, these results suggest complex interactions between genetically determined dopamine signalling and risk for schizophrenia on brain activity in the prefrontal cortex during emotion processing. On the other hand, the effects in the striatum may represent state-related epiphenomena of the disorder itself.

DAT by perceived MC interaction on human prefrontal activity and connectivity during emotion processing

BACKGROUND

Maternal care (MC) and dopamine modulate brain activity during emotion processing in inferior frontal gyrus (IFG), striatum and amygdala. Reuptake of dopamine from the synapse is performed by the dopamine transporter (DAT), whose abundance is predicted by variation in its gene (DAT 3'VNTR; 10 > 9-repeat alleles). Here, we investigated the interaction between perceived MC and DAT 3'VNTR genotype on brain activity during processing of aversive facial emotional stimuli.

METHODS

Sixty-one healthy subjects were genotyped for DAT 3'VNTR and categorized in low and high MC individuals. They underwent functional magnetic resonance imaging while performing a task requiring gender discrimination of facial stimuli with angry, fearful or neutral expressions.

RESULTS

An interaction between facial expression, DAT genotype and MC was found in left IFG, such that low MC and homozygosity for the 10-repeat allele are associated with greater activity during processing of fearful faces. This greater activity was also inversely correlated with a measure of emotion control as scored with the Big Five Questionnaire. Moreover, MC and DAT genotype described a double dissociation on functional connectivity between IFG and amygdala.

CONCLUSION

These findings suggest that perceived early parental bonding may interact with DAT 3'VNTR genotype in modulating brain activity during emotionally relevant inputs.

Quantitative analysis of elastography images in the detection of breast cancer

PURPOSE

The aim of this study was to develop a quantitative method for breast cancer diagnosis based on elastosonography images in order to reduce whenever possible unnecessary biopsies. The proposed method was validated by correlating the results of quantitative analysis with the diagnosis assessed by histopathologic exam.

MATERIAL AND METHODS

109 images of breast lesions (50 benign and 59 malignant) were acquired with the traditional B-mode technique and with elastographic modality. Images in Digital Imaging and COmmunications in Medicine format (DICOM) were exported into a software, written in Visual Basic, especially developed to perform this study. The lesion was contoured and the mean grey value and softness inside the region of interest (ROI) were calculated. The correlations between variables were investigated and receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic accuracy of the proposed method. Pathologic results were used as standard reference.

RESULTS

Both the mean grey value and the softness inside the ROI resulted statistically different at the t test for the two populations of lesions (i.e., benign versus malignant): p<0.0001. The area under the curve (AUC) was 0.924 (0.834-0.973) and 0.917 (0.826-0.970) for the mean grey value and for the softness respectively.

CONCLUSIONS

Quantitative elastosonography is a promising ultrasound technique in the detection of breast cancer but large prospective trials are necessary to determine whether quantitative analysis of images can help to overcome some pitfalls of the methodic.

Combined hyperlipidaemia as a presenting sign of cholesteryl ester storage disease

Lysosomal acid lipase (LAL) deficiency results in Wolman disease and cholesteryl ester storage disease (CESD), a more benign form. CESD is a recessive disorder characterized by hypercholesterolaemia, hypertriglyceridaemia, low blood HDL and variable phenotype, while hepatomegaly is usually evident during childhood or adolescence. An 11-year-old girl was referred to our department for combined hyperlipidaemia (total cholesterol 323, triglycerides 259 mg/dl). All family members had normal lipid profile and liver function tests. At 8 years she was admitted for acute Epstein-Barr virus infection, with hepatosplenomegaly and elevation of liver enzymes. Liver-spleen enlargement resolved, but serum alanine aminotransferase and aspartate aminotransferase were persistently twice the upper limits, with other liver function tests within the normal range. Ultrasonography showed normal liver and spleen size and minimal hepatic steatosis. Infectious, autoimmune and metabolic causes of elevated liver enzymes were ruled out, including glycogen storage disease. Dysbetalipoproteinaemia was also ruled out (ApoE phenotype: E3E3). In the following 2 years the girl was symptom-free, BMI was at the 50th-75th centile for age and lipid profile was unchanged despite a low-fat diet. At 13 years of age, low acid lipase activity was demonstrated in leukocytes (10 nmol/h/ per mg protein, normal 140-380) and cultured skin fibroblasts (181 nmol/h per mg protein, normal 1100-2400), leading to diagnosis of CESD. CESD usually progresses to hepatic fibrosis, with high risk of premature atherosclerosis. CESD prevalence may be underestimated in the general population. The diagnosis may be considered in all subjects with atypical combined hyperlipidaemia (usually dominant in transmission or related to metabolic syndrome) and atypical 'fatty liver disease', in the absence of overweight.

Long term effects of bosentan treatment in adult patients with pulmonary arterial hypertension related to congenital heart disease (Eisenmenger physiology): safety, tolerability, clinical, and haemodynamic effect

BACKGROUND

Oral bosentan is an established treatment for pulmonary arterial hypertension (PAH).

OBJECTIVE

To evaluate safety, tolerability, and clinical and haemodynamic effects of bosentan in patients with PAH related to congenital heart disease (CHD).

PATIENTS

22 patients with CHD related PAH (8 men, 14 women, mean (SD) age 38 (10) years) were treated with oral bosentan (62.5 mg x 2/day for the first 4 weeks and then 125 mg x 2/day).

MAIN OUTCOME MEASURES

Clinical status, liver enzymes, World Health Organisation (WHO) functional class, resting oxygen saturations and 6-min walk test (6MWT) were assessed at baseline and at 1, 3, 6, and 12 months. Haemodynamic evaluation with cardiac catheterisation was performed at baseline and at 12 month follow-up.

RESULTS

12 patients had ventricular septal defect, 5 atrioventricular canal, 4 single ventricle, and 1 atrial septal defect. All patients tolerated bosentan well. No major side effects were seen. After a year of treatment, an improvement was seen in WHO functional class (2.5 (0.7) v 3.1 (0.7); p<0.05), oxygen saturation at rest (87 (6%) v 81 (9); p<0.001), heart rate at rest (81 (10) v 87 (14) bpm; p<0.05), distance travelled in the 6MWT (394 (73) v 320 (108) m; p<0.001), oxygen saturation at the end of the 6MWT (71 (14) v 63 (17%); p<0.05), Borg index (5.3 (1.8) v 6.5 (1.3); p<0.001), pulmonary vascular resistances index (14 (9) v 22 (12) WU m(2); p<0.001), systemic vascular resistances index (23 (11) v 27 (10) WU.m(2); p<0.01), pulmonary vascular resistances index/systemic vascular resistances index (0.6 (0.5) v 0.9 (0.6); p<0.05); pulmonary (4.0 (1.3) v 2.8 (0.9) l/min/m2; p<0.001) and systemic cardiac output (4.2 (1.4) v 3.4 (1.1) l/min/m2; p<0.05).

CONCLUSIONS

Bosentan was safe and well tolerated in adults with CHD related PAH during 12 months of treatment. Clinical status, exercise tolerance, and pulmonary haemodynamics improved considerably.

Influenza vaccination in patients on long-term anticoagulant therapy

The study evaluates the risk/benefit of influenza vaccination in patients on stable long-term oral anticoagulant therapy (OAT). One hundred and four consecutive patients with indication for influenza vaccination were randomized to receive one dose of 2004/2005 influenza vaccine followed by placebo after 6 weeks, or vice versa, in a cross-over blinded trial. All patients were tested for anticoagulation levels and for hemagglutination inhibiting antibody titres against the influenza vaccine antigens. The highly protective antibody titres induced by influenza vaccination and the absence of statistically relevant interactions between vaccination and OAT suggest that influenza vaccination can be used safely and successfully in elderly patients on OAT.

Performance comparison of three assay methods used in fasting and postmethionine load plasma homocysteine determinations from patients with vascular disease

Several methods have been developed for measurement of plasma total homocysteine (tHcy), a proven graded risk factor for cardiovascular diseases. The aim of the study was to compare 3 commonly used clinical methods (enzyme immunoassay, Axis Biochemicals, Oslo, Norway; and fluorescence polarization immunoassay [FPIA], Axis, on the Abbott IMx System, Abbott Laboratories, Abbott Park, IL; and BioRad high-performance liquid chromatography [HPLC], Laboratories, Munich, Germany) for tHcy determination in samples from cardiovascular patients also undergoing methionine load measurement. Only HPLC reached the required coefficient of variation (<6%) for desirable performance for tHcy concentrations ranging between 0.68 and 5.41 mg/L (5 and 40 micromol/L). A higher variability was observed for postmethionine load vs fasting samples, which reached statistical significance for FPIA (P = .0013). The closest agreement between methods was observed between HPLC and FPIA for fasting tHcy concentrations (-0.23 mg/L [-1.69 micromol/L], -30% to 8%).Both immunoassays could be suitable alternatives for laboratories with high workloads when HPLC is not available. Differences among tHcy values must be taken into account when these methods will be used interchangeably for diagnosis and monitoring of treatment.

Safety and Efficacy of Ximelagatran: Meta-Analysis of the Controlled Randomized Trials for the Prophylaxis or Treatment of Venous Thromboembolism

BACKGROUND

Ximelagatran has been approved in Europe for VTE prophylaxis in orthopedic surgery at fixed doses and without laboratory monitoring. Aim of the study was to evaluate safety and efficacy of ximelagatran in a meta-analysis of prophylaxis and/or treatment randomized controlled trials.

METHODS

Absolute risk of events for ximelagatran and OR for its comparison with LMWH and coumarins were calculated. Subgroup analysis was performed for ximelagatran regimen, comparator agent, type of surgery, starting time of prophylaxis.

RESULTS

Twelve studies and 16,992 patients were meta-analysed. Ximelagatran showed an absolute risk of major VTE of 4.04% and 1.69% and of major bleedings of 1.68% and 1.03% in prophylaxis and treatment trials, respectively. In prophylaxis trials, a significant excess mortality (OR: 2.5; 95% CI: 1.02 - 6.13) and an excess in major bleedings (OR: 1.41; 95% CI: 0.93 - 2.14) was found in the whole ximelagatran group. No evidence of treatment effect for major VTE was seen in the comparison with LMWH (OR: 1.01; 95% CI: 0.52 - 1.97). The cohort of patients treated with 24 mg b.i.d. showed similar results. An increase in the absolute risk of bleeding (from 1.04% to 3.03%) was found between post and preoperative administration of ximelagatran. Major VTE risk was increased when ximelagatran was compared to b.i.d. LMWH.

CONCLUSIONS

Ximelagatran can be considered for its potential advantages for prevention and treatment of VTE. Future efforts are needed by researchers to prospectively investigate the best postoperatively starting time and by clinicians to monitor overall mortality in prophylactic use.

Sildenafil increases cerebrovascular reactivity: A transcranial Doppler study

The authors performed a double-blind, placebo-controlled study in 28 patients to evaluate the effects of sildenafil on cerebral hemodynamics. A significant improvement of cerebrovascular reactivity, without any modification of other variables, was recorded 1 hour after the administration of 50 mg sildenafil. Further investigations are needed to evaluate whether cerebrovascular reactivity improvement could contribute to triggering sildenafil-induced migraine.

CagA-positive Helicobacter pylori strains may influence the natural history of atherosclerotic stroke

OBJECTIVE

To test the hypothesis that infection with virulent cytotoxin-associated gene-A (CagA)-bearing Helicobacter pylori strains influences the atherosclerotic process and the clinical course in atherosclerotic stroke patients.

METHODS

ELISA was used to assess the seroprevalence of infection by H. pylori and CagA-positive strains in 185 patients. Intima-media thickness (IMT) was determined by Doppler ultrasound. Baseline, 1-week, and 1-month NIH Stroke Scale (NIHSS) scores were used to evaluate the short-term clinical course.

RESULTS

H. pylori infection was found in 79% of patients; 58% of these tested positive for CagA. IMT was higher among CagA-positive patients than among CagA-negative ones (1.13 +/- 0.26 mm vs 0.97 +/- 0.15 mm; univariate analysis, p = 0.0001; multivariate analysis, odds ratio [OR], 2.36; 95% CI, 1.57 to 3.54; p = 0.0001) or H. pylori-negative ones (1.01 +/- 0.17 mm; univariate analysis, p = 0.007; multivariate analysis, OR, 1.90; 95% CI, 1.22 to 2.97; p = 0.005). CagA-positive patients had poorer initial outcomes based on serial measurements of the NIHSS score (repeated measures analysis of variance, p < 0.0001). No significant difference in IMT and NIHSS score was found between H. pylori-positive and H. pylori-negative patients.

CONCLUSIONS

Infection with cytotoxin-associated gene-A-positive Helicobacter pylori strains in atherosclerotic stroke patients is associated with greater intima-media thickness and poorer short-term outcome compared with cytotoxin-associated gene-A-negative patients.

Fragmentations and reactions of the organophosphate insecticide Diazinon and its oxygen analog Diazoxon studied by electrospray ionization ion trap mass spectrometry

The fragmentations and reactions of Diazinon and related compounds have been studied by electrospray ionization ion trap mass spectrometry. Several novel fragmentation and rearrangements have been observed, including an intramolecular thiono-thiolo rearrangement. The stability, in the gas-phase, of the protomers of 2-isopropyl-4-methyl-6-pyrimidinol has been demonstrated. The complexity of the gas phase ion processes observed suggest that, at present, caution should be exercised in using this approach for the analysis of environmental and other samples until our understanding of these processes increases considerably.

Phyto-oestrogens in the prophylaxis of menstrual migraine

BACKGROUND

Falling levels of estrogen is the major provocative factor in migraine associated with menstruation.

OBJECTIVE

We assessed the efficacy of the combination of two phyto-oestrogens, as perimenstrual, prophylactic treatment of menstrual migraine and tested their effect on cerebral haemodynamic.

SUBJECTS AND METHODS

Women with a history of menstrual migraine (i.e., attacks occurring exclusively on day 1+/-2 days of menstruation and at no other time of the cycle) were included in the study. Eleven women fulfilling the inclusion criteria underwent to a 3-month cyclic treatment with 56 mg of genisteine and 20 mg of diadzeine per day. Transcranial doppler evaluation (TCD) was performed at baseline and after treatment.

RESULTS

Among the ten women who completed the study the average number of days with migraine during the baseline period decreased significantly after 3 months of therapy (P < 0.005). There were no major side-effects. Therapy did not affect cerebral blood flow velocities.

CONCLUSIONS

Phyto-oestrogens appear to be an effective treatment in menstrual migraine prophylaxis. This effect seems to be unrelated to cerebral hemodynamic. Placebo-controlled trials on larger number of patients are necessary to confirm our findings.

Hernia repair in the Lombardy region in 2000: Preliminary results

Hernia repair is the most common surgical procedure in general surgery in Italy and in the Lombardy region. In the last decade, the use of mesh, the concept of a tension-free technique, and the postoperative rate of recurrences after Bassini or Shouldice operations have completely changed the surgical approach to hernia repair. For this reason, we sent a questionnaire to 148 surgical departments in the Lombardy region to investigate about total hernia operations performed in 2000 in Lombardy, the surgical approach, the surgical techniques used, the type of anesthesia and the hospital stay. One hundred five out of 148 surgical departments returned the questionnaire, and we collected information on a total of 16,935 surgical operations for hernia: 16,494 were performed using tension-free techniques. The inguinal anterior approach is the one of choice for primary and recurrent inguinal hernia, whereas the open preperitoneal and laparoscopic approaches are limited to bilateral and recurrent hernias. The majority of cases were treated under locoregional anesthesia and with a hospital stay of two nights.

Carotid artery intima-media thickness and lacunar versus nonlacunar infarcts

BACKGROUND AND PURPOSE

Increases in the thickness of the intima and media of the carotid artery have been associated with an increased risk of myocardial infarction and stroke in subjects without a history of cardiovascular disease. Lacunar infarcts, one of the most common subtype of ischemic stroke, show unique pathological and clinicoradiological characteristics. The present study examines the relationship between vascular risk factors, including carotid artery intima-media thickness (IMT), and lacunar versus nonlacunar infarcts.

METHODS

We collected data from patients with acute ischemic stroke admitted to hospital. Patients and 129 control subjects underwent B-mode ultrasonographic measurements of IMT of the common carotid artery. We examined the association of lacunar and nonlacunar infarcts with age, sex, and potential vascular risk factors.

RESULTS

Of 292 adult patients with an acute first-ever ischemic stroke, 96 were considered lacunar and 196 were considered nonlacunar strokes. We did not find a significantly different percentage of diabetes, smoking, hypertension, dyslipidemia, myocardial infarction, and previous transient ischemic attack between the 2 groups of patients. The multinomial logistic regression procedure selected carotid artery IMT and atrial fibrillation as the only independent factors able to discriminate between lacunar and nonlacunar patients. IMT values were significantly higher in patients with nonlacunar stroke versus both those with lacunar stroke and control subjects.

CONCLUSIONS

The present results indicate the usefulness of noninvasive measurement of IMT with ultrasonic techniques as a diagnostic tool that may help to identify different subtypes of ischemic stroke patients. The noninvasive measurements may have predictive power with respect to lacunar versus nonlacunar infarcts.

[Small bowel diverticula in adults: clinical and therapeutic features. Report of 2 cases and review of the literature]

The true diverticula of the small bowell are a very rare observation in clinical practice; they have a malformative origin and, occasionally, are acquired, contrary to what observed in the colon, where they are frequently an acquired pathology. They can involve the small bowel as a single lesion (Meckel's diverticulum), or as a segmentary disease (duodenal diverticula), or as a diffused diverticulosis. Generally they are asymptomatic and rarely they produce a true pathology. The symptomatic disease is primarily found in pediatric age and it requires a surgical procedure. This makes even more rare the diverticular pathology in the adult. The authors report 1 case of intestinal occlusion due to ileoileo-colic invagination arising from a Meckel's diverticulum and 1 case of intestinal occlusion in presence of a severe and acute diffuse diverticulosis of the small bowell, both in adult patients.

[Late post-traumatic diaphragmatic hernia: unusual cause of colonic occlusion]

Traumatic diaphragmatic rupture is not an uncommon problem, particularly in the last few years because of the increasing number of road accidents, improved diagnostic techniques and resuscitation techniques after serious traumas. In a certain number of cases, post-traumatic diaphragmatic hernias may become clinically manifest only months or years after thoracic or abdominal trauma and are still a challenge to surgeons because of the vague clinical symptoms and the diagnostic difficulties involved. The Authors report a case of acute colon occlusion due to diaphragmatic hernia 24 months after thoraco-abdominal trauma. None of the radiological or endoscopic examinations demonstrated the presence of diaphragmatic hernia. Laparoscopy showed a diaphragmatic rupture with incarceration of the left colonic segment. The laparoscopic procedure was converted for technical reasons and the diaphragmatic defect was closed with a primary suture.

Influence of physiologic oscillation of estrogens on cerebral hemodynamics

The interactions between estrogens and the cerebrovascular system are complex and not fully understood. There are evidences suggesting that the hormones confer protection against cerebral ischemia. Our aim in this study was to investigate the effects of physiological variations of estradiol plasmatic concentration on cerebral hemodynamics. We investigated cerebrovascular reactivity to hypercapnia with transcranial Doppler ultrasonography and the breath-holding index method in the right middle cerebral artery of 20 young women during the menstrual and the ovulatory phase. Data were compared with those of 20 men matched for age. The mean value of the breath-holding index was significantly higher (p<0.001) in females during the ovulatory phase than in the menstrual phase. In men, values were similar to those of women during the menstrual phase. These results suggest that estrogens influence the adaptation capacity of the cerebrovascular system. The possible pathophysiological implications of the relationships between sex hormones and cerebral hemodynamics deserve further investigation.

Ca2+ channels of the L-type in peripheral blood lymphocytes of essential hypertensives

Ca2+ channels of the L-type were assayed in human peripheral blood lymphocytes of normotensive control subjects and of essential hypertensives using radioligand binding assay techniques. The dihydropyridine Ca2+ channel blocker [3H](+)-PN 200-110 [isopropyll-4-(2,1,3-benzoxadiazol-4-yl)1,4-dihydro-5-methox ycarbonyl-2,6-dimethyl-3-pyridine carboxylate] was used as a ligand. [3H](+)-PN 200 110 was bound specifically to human peripheral blood lymphocytes in a manner consistent with the labeling of Ca2+ channels of the L-type. No significant differences in the dissociation constant (Kd), in the maximum density of binding sites (Bmax) or in the pharmacological profile of [3H](+)-PN 200 110 binding were found between normotensive subjects and different degree essential hypertensives. Analysis of the intralymphocytic free Ca2+ concentration did not reveal differences between normotensive subjects and essential hypertensives. Although hypertension is associated with altered membrane handling of Ca2+, no changes in the expression of peripheral blood lymphocyte Ca2+ channels of the L-type or in intralymphocytic Ca2+ concentrations were found in essential hypertensives. Human peripheral blood lymphocytes therefore cannot represent a peripheral marker of altered Ca2+ handling in hypertension.

Density and localization of calcium channels of the L-type in human pulmonary artery

The pharmacological profile and the anatomical localization of Ca2+ channels of the L-type were investigated in the human pulmonary artery to identify possible mechanisms involved in the regulation of the pulmonary vascular tone. Analysis was performed on slide-mounted frozen sections of human pulmonary artery using radioligand binding assay techniques associated with light microscope autoradiography. [3H]-Nicardipine was used as ligand. Human renal and right coronary arteries also were used as systemic reference arteries. Binding of [3H]-nicardipine to sections of human pulmonary artery was time-, temperature- and concentration-dependent, saturable and reversible. In the human pulmonary artery, the apparent equilibrium dissociation constant (Kd) was 0.12+/-0.02 nM and the maximum density of binding sites (Bmax) was 38.15+/-2.25 fmol/mg tissue. Kd values were 0.3+/-0.01 nM and 0.5+/-0.02 in the human renal artery and right coronary artery respectively. Bmax values were 248+/-16 fmol/mg tissue and 173+/-9.5 fmol/mg tissue in the human renal artery and right coronary artery respectively. The pharmacological profile of [3H]-nicardipine binding to sections of human pulmonary artery was consistent with the labeling of Ca2+ channels of the L-type. It was similar in the pulmonary artery and in the human renal and right coronary arteries. Light microscope autoradiography revealed a high density of [3H]-nicardipine binding sites within smooth muscle of the tunica media of human pulmonary artery as well as of human renal and right coronary arteries. A lower accumulation of the radioligand occurred in the tunica adventitia. No specific binding was noticeable in the tunica intima. Our data suggest that human pulmonary artery expresses Ca2+ channels of the L-type sensitive to dihydropyridines. These sites have similar affinity and lower density than those expressed by systemic arteries. The presence of Ca2+ channels of the L-type in human pulmonary artery suggests that their pharmacological manipulation may be considered in the treatment of pulmonary hypertension.

Pharmacological characterization and autoradiographic localization of a putative dopamine D4 receptor in the heart

1. The pharmacological profile and the anatomical localization of a putative dopamine D4 receptor were assessed in sections of rat and human atria and ventricles using combined radioligand binding and autoradiographic techniques with [3H]-spiperone as a ligand. 2. [3H]-Spiperone was bound specifically to sections of human and rat atria and ventricles. The binding was time-, temperature- and concentration-dependent, belonging to a single class of high-affinity sites. In atria, the dissociation constant value (Kd) was 0.45 nM in rats and 0.32 nM in humans, and the maximum density of binding sites (Bmax) was 31.6+/-2.9 fmol mg(-1) tissue in rats and 18.8+/-0.7 fmol mg(-1) tissue in humans. In ventricles, Kd was 0.38 nM in rats and 0.39 nM in humans, and the Bmax was 43.5+/-3.0 fmol mg(-1) tissue in rats and 56.4+/-3.2 fmol mg(-1) tissue in humans. 3. The pharmacological profile of [3H]-spiperone binding to sections of both rat and human atria and ventricles was consistent with the labelling of dopamine D2-like receptors. [3H]-Spiperone binding was more sensitive to displacement by the neuroleptic clozapine in sections of atria than of ventricles, suggesting the expression of a dopamine D4 receptor in atrial tissue. Moreover, preincubation of some sections with a dopamine D4 receptor antibody and subsequent exposure to [3H]-spiperone caused a remarkable decrease of radioligand binding to sections of atria, but only a slight reduction of binding to sections of ventricles. 4. Light microscope autoradiography revealed the accumulation of silver grains over atrial tissue within atrial myocardiocytes. A higher density of silver grains was developed in rat than in human atria. In ventricles, silver grains were accumulated primarily in cluster areas both in rats and in humans. 5. The above findings suggest the expression of a dopamine D4 receptor in rat atria, but not in ventricles. A similar site was identified in human atria. The possible relevance of a dopamine D4 receptor in the heart is discussed.