In-silico testing of new pharmacology for restoring inhibition and human cortical function in depression

Reduced inhibition by somatostatin-expressing interneurons is associated with depression. Administration of positive allosteric modulators of α5 subunit-containing GABAA receptor (α5-PAM) that selectively target this lost inhibition exhibit antidepressant and pro-cognitive effects in rodent models of chronic stress. However, the functional effects of α5-PAM on the human brain in vivo are unknown, and currently cannot be assessed experimentally. We modeled the effects of α5-PAM on tonic inhibition as measured in human neurons, and tested in silico α5-PAM effects on detailed models of human cortical microcircuits in health and depression. We found that α5-PAM effectively recovered impaired cortical processing as quantified by stimulus detection metrics, and also recovered the power spectral density profile of the microcircuit EEG signals. We performed an α5-PAM dose-response and identified simulated EEG biomarker candidates. Our results serve to de-risk and facilitate α5-PAM translation and provide biomarkers in non-invasive brain signals for monitoring target engagement and drug efficacy.

In-silico EEG biomarkers of reduced inhibition in human cortical microcircuits in depression

Reduced cortical inhibition by somatostatin-expressing (SST) interneurons has been strongly associated with treatment-resistant depression. However, due to technical limitations it is impossible to establish experimentally in humans whether the effects of reduced SST interneuron inhibition on microcircuit activity have signatures detectable in clinically-relevant brain signals such as electroencephalography (EEG). To overcome these limitations, we simulated resting-state activity and EEG using detailed models of human cortical microcircuits with normal (healthy) or reduced SST interneuron inhibition (depression), and found that depression microcircuits exhibited increased theta, alpha and low beta power (4-16 Hz). The changes in depression involved a combination of an aperiodic broadband and periodic theta components. We then demonstrated the specificity of the EEG signatures of reduced SST interneuron inhibition by showing they were distinct from those corresponding to reduced parvalbumin-expressing (PV) interneuron inhibition. Our study thus links SST interneuron inhibition level to distinct features in EEG simulated from detailed human microcircuits, which can serve to better identify mechanistic subtypes of depression using EEG, and non-invasively monitor modulation of cortical inhibition.

Nuclear and magnetic spin structure of the antiferromagnetic triangular lattice compound LiCrTe2 investigated by [Formula: see text]SR, neutron and X-ray diffraction

Two-dimensional (2D) triangular lattice antiferromagnets (2D-TLA) often manifest intriguing physical and technological properties, due to the strong interplay between lattice geometry and electronic properties. The recently synthesized 2-dimensional transition metal dichalcogenide LiCrTe[Formula: see text], being a 2D-TLA, enriched the range of materials which can present such properties. In this work, muon spin rotation ([Formula: see text]SR) and neutron powder diffraction (NPD) have been utilized to reveal the true magnetic nature and ground state of LiCrTe[Formula: see text]. From high-resolution NPD the magnetic spin order at base-temperature is not, as previously suggested, helical, but rather collinear antiferromagnetic (AFM) with ferromagnetic (FM) spin coupling within the ab-plane and AFM coupling along the c-axis. The value if the ordered magnetic Cr moment is established as [Formula: see text]. From detailed [Formula: see text]SR measurements we observe an AFM ordering temperature [Formula: see text] K. This value is remarkably higher than the one previously reported by magnetic bulk measurements. From [Formula: see text]SR we are able to extract the magnetic order parameter, whose critical exponent allows us to categorize LiCrTe[Formula: see text] in the 3D Heisenberg AFM universality class. Finally, by combining our magnetic studies with high-resolution synchrotron X-ray diffraction (XRD), we find a clear coupling between the nuclear and magnetic spin lattices. This suggests the possibility for a strong magnon-phonon coupling, similar to what has been previously observed in the closely related compound LiCrO[Formula: see text].

Reduced inhibition in depression impairs stimulus processing in human cortical microcircuits

Cortical processing depends on finely tuned excitatory and inhibitory connections in neuronal microcircuits. Reduced inhibition by somatostatin-expressing interneurons is a key component of altered inhibition associated with treatment-resistant major depressive disorder (depression), which is implicated in cognitive deficits and rumination, but the link remains to be better established mechanistically in humans. Here we test the effect of reduced somatostatin interneuron-mediated inhibition on cortical processing in human neuronal microcircuits using a data-driven computational approach. We integrate human cellular, circuit, and gene expression data to generate detailed models of human cortical microcircuits in health and depression. We simulate microcircuit baseline and response activity and find a reduced signal-to-noise ratio and increased false/failed detection of stimuli due to a higher baseline activity in depression. We thus apply models of human cortical microcircuits to demonstrate mechanistically how reduced inhibition impairs cortical processing in depression, providing quantitative links between altered inhibition and cognitive deficits.

Mapping Inter-individual Functional Connectivity Variability in TMS Targets for Major Depressive Disorder

Transcranial magnetic stimulation (TMS) is an emerging alternative to existing treatments for major depressive disorder (MDD). The effects of TMS on both brain physiology and therapeutic outcomes are known to be highly variable from subject to subject, however. Proposed reasons for this variability include individual differences in neurophysiology, in cortical geometry, and in brain connectivity. Standard approaches to TMS target site definition tend to focus on coordinates or landmarks within the individual brain regions implicated in MDD, such as the dorsolateral prefrontal cortex (dlPFC) and orbitofrontal cortex (OFC). Additionally considering the network connectivity of these sites (i.e., the wider set of brain regions that may be mono- or poly-synaptically activated by TMS stimulation) has the potential to improve subject-specificity of TMS targeting and, in turn, improve treatment outcomes. In this study, we looked at the functional connectivity (FC) of dlPFC and OFC TMS targets, based on induced electrical field (E-field) maps, estimated using the SimNIBS library. We hypothesized that individual differences in spontaneous functional brain dynamics would contribute more to downstream network engagement than individual differences in cortical geometry (i.e., E-field variability). We generated individualized E-field maps on the cortical surface for 121 subjects (67 female) from the Human Connectome Project database using tetrahedral head models generated from T1- and T2-weighted MR images. F3 and Fp1 electrode positions were used to target the left dlPFC and left OFC, respectively. We analyzed inter-subject variability in the shape and location of these TMS target E-field patterns, their FC, and the major functional networks to which they belong. Our results revealed the key differences in TMS target FC between the dlPFC and OFC, and also how this connectivity varies across subjects. Three major functional networks were targeted across the dlPFC and OFC: the ventral attention, fronto-parietal and default-mode networks in the dlPFC, and the fronto-parietal and default mode networks in the OFC. Inter-subject variability in cortical geometry and in FC was high. Our analyses showed that the use of normative neuroimaging reference data (group-average or representative FC and subject E-field) allows prediction of which networks are targeted, but fails to accurately quantify the relative loading of TMS targeting on each of the principal networks. Our results characterize the FC patterns of canonical therapeutic TMS targets, and the key dimensions of their variability across subjects. The high inter-individual variability in cortical geometry and FC, leading to high variability in distributions of targeted brain networks, may account for the high levels of variability in physiological and therapeutic TMS outcomes. These insights should, we hope, prove useful as part of the broader effort by the psychiatry, neurology, and neuroimaging communities to help improve and refine TMS therapy, through a better understanding of the technology and its neurophysiological effects.

OP0273 ADHERENCE TO COLCHICINE TREATMENT AND COLCHICINE RESISTANCE IN A MULTICENTRIC FMF NATIONAL COHORT

Background:

Colchicine is the standard treatment for Familiar Mediterranean Fever (FMF), however about 5% of patients experience colchicine resistance. There is no standard definition of colchicine resistance. Recently a panel of experts elaborated a new definition based on a Delphi consensus approach.

Objectives:

We aim to describe main features of the disease and clinical outcome of a cohort of FMF patients with particular interest on the colchicine resistance and tolerability according to the definitions proposed by the recent consensus.

Methods:

Since November 2009, 425 Italian pediatric and adult FMF patients (pts) from 13 centers were enrolled in a national longitudinal cohort study, using the international EUROFEVER registry. Demographic, genetic and clinical data, including response to treatment, were analyzed. Supplementary information on health related quality of life and treatment adherence was also collected by a specific questionnaire.

Results:

Complete information were available in 341 pts (189 M and 152 F, 211 children and 120 adults). The median age at disease onset was 5.0 years (1 m-59 y); the mean diagnostic delay was 8.7 y (range 0-61 y). The median age at enrollment was 12.1 y (range 3 m - 82 y). The MEFV genotype was the following: 103 (30.2%) pts carried biallelic pathogenic variants; 59 (17.3%) one pathogenic variants and one VOUS /LB variant; 27 (7.9%) had biallelic VOUS/LB variants; 97 (28.45%) were heterozygous for pathogenic variants; 30 (8.8%) were heterozygous for VOUS/LB, 25 (7.33%) were genetically negative.

Colchicine treatment was used in 280 pts; during treatment, biologic treatment (anti-IL1) in 22 pts. 61 pts received NSAID or steroid on demand.

We analyzed the behavior of the pts treated with colchicine according to the statements on colchicine resistance/intolerance defined by Ozen et al (1) (Table 1).

Table 1.Adherence62% displayed a total adherence (> 90% of prescription); 10.8% a good adherence (50-89% of prescriptions); 1.9% poor adherence (< 50% of prescriptions); 0.9% no adherenceDose adjustment criteria/ Recommended maximum colchicine doseMean colchicine dose:Pts <5 years: 0.57mg/de (std. dev. 0.18)5-10 year: 0.77mg/die (std. dev. 0.23)10-18 years: 1.1mg/die (std. dev. 0.39)Adults: 1.16 mg/die (std. dev. 0.37)Pts with a dose inferior to the minimum recommended dose5-10 years: 2.5%10-18 years: 15%Adults: 4%Resistance to ColchicineResistance was be defined as persistence of fever attacks, despite optimal treatment. 41.6% pts had a complete disease control32.8% Pts had < 1 episode/month for 3 months25.5% had ≥1 episode/month for 3 monthsInclusion of secondary amyloidosis in the definition of colchicine resistance5 adult pts (1.5%) displayed amyloidosisColchicine intolerance11 pts (3.2%) withdraw colchicine because of drug intolerancePatient quality of life and patient-reported outcomes20.7% of pts experience fatigue or chronic pain, 16.9% limitations in daily activities, and 16.9% have lost school/work days.

Conclusion:

Almost 58% of FMF pts display disease activity despite colchicine treatment. The treatment is generally under-dosed, especially in children. The adherence and the compliance to the treatment is generally good.

References:

[1]Ozen S et all. Recommendation on colchicine dosing and definition of colchicine resistance/intolerance in the management of FMF. Pediatric Rheumatology, 2019.

Acknowledgments:

This research was financial supported by Novartis AG

Disclosure of Interests:

Romina Gallizzi: None declared, Marta Bustaffa: None declared, Francesca Mazza: None declared, Diana Sutera: None declared, Giovanna Fabio: None declared, Laura Obici: None declared, Maria Alessio: None declared, Donato Rigante: None declared, Luca Cantarini: None declared, Antonella Insalaco: None declared, Marco Cattalini: None declared, Maria Cristina Maggio: None declared, Gabriele Simonini: None declared, Alma Nunzia Olivieri: None declared, Serena Pastore: None declared, Maddalena Lancieri: None declared, Nicolino Ruperto Grant/research support from: Bristol-Myers Squibb, Eli Lily, F Hoffmann-La Roche, GlaxoSmithKline, Janssen, Novartis, Pfizer, Sobi (paid to institution), Consultant of: Ablynx, AbbVie, AstraZeneca-Medimmune, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Eli Lily, EMD Serono, GlaxoSmithKline, Hoffmann-La Roche, Janssen, Merck, Novartis, Pfizer, R-Pharma, Sanofi, Servier, Sinergie, Sobi, Takeda, Speakers bureau: Ablynx, AbbVie, AstraZeneca-Medimmune, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, Eli Lily, EMD Serono, GlaxoSmithKline, Hoffmann-La Roche, Janssen, Merck, Novartis, Pfizer, R-Pharma, Sanofi, Servier, Sinergie, Sobi, Takeda, Marco Gattorno Consultant of: Sobi, Novartis, Speakers bureau: Sobi, Novartis

Effect of Theta Transcranial Alternating Current Stimulation and Phase-Locked Transcranial Pulsed Current Stimulation on Learning and Cognitive Control

Non-invasive brain stimulation (NIBS) is emerging as a robust treatment alternative for major depressive disorder, with a potential for achieving higher remission rates by providing targeted stimulation to underlying brain networks, such as the salience network (SN). Growing evidence suggests that these therapeutic effects are dependent on the frequency and phase synchrony between SN oscillations and stimulation as well as the task-specific state of the SN during stimulation. However, the development of phase-synchronized non-invasive stimulation has proved challenging until recently. Here, we use a phase-locked pulsed brain stimulation approach to study the effects of two NIBS methods: transcranial alternating current stimulation (tACS) versus phase-locked transcranial pulsed current stimulation (tPCS), on the SN during an SN activating task. 20 healthy volunteers participated in the study. Each volunteer partook in four sessions, receiving one stimulation type at random (theta-tACS, peak tPCS, trough tPCS or sham) while undergoing a learning game, followed by an unstimulated test based on learned material. Each session lasted approximately 1.5 h, with an interval of at least 2 days to allow for washout and to avoid cross-over effects. Our results showed no statistically significant effect of stimulation on the event related potential (ERP) recordings, resting electroencephalogram (EEG), and the performance of the volunteers. While stimulation effects were not apparent in this study, the nominal performance of the phase-locking algorithm offers a technical foundation for further research in determining effective stimulation paradigms and conditions. Specifically, future work should investigate stronger stimulation and true task-specific stimulation of SN nodes responsible for the task as well as their recording. If refined, NIBS could offer an effective, homebased treatment option.

Relationship between body mass index, age and hypoxemia in patients with extremely severe obesity undergoing bariatric surgery

BACKGROUND

Morbid obesity is frequently accompanied by serious co-morbidity, enclosed obstructive sleep apnea and hypoventilation syndrome, and thus many morbidly obese patients require surgical interventions. The aim of this study was to evaluate the relationship between arterial oxygen (pO₂) and carbon dioxide (pCO₂) partial pressure, age, loss of excess weight, and body mass index (BMI) in obese patients scheduled to undergo bariatric surgery.

PATIENTS AND METHODS

A group of 11 patients (4 men, 7 women, median age 38 years, range 23-58 years) with extremely severe obesity (BMI>50 kg/m²) underwent laparoscopic Roux-en-Y gastric bypass. Preoperatively, BMI, pO₂, and pCO₂ were 52.7±2.4 kg/m², and 70.9±5.3 and 43.1±6.5 mmHg, respectively. Hypoxemia (pO₂<75 mmHg) was present in all patients, but no relationship between BMI and age (R=-0.24, p=0.44) or between BMI and pO₂ (R=0.09, p=0.77) was found.

RESULTS

As expected, there was a significant correlation between age and both pO₂ (R=-0.58, p=0.04) and pCO₂ (R=0.85, p=0.0004), while no relationship between BMI and age (R=-0.24, p=0.44), nor between BMI and pO₂ (R=0.09, p=0.77) was found. Finally, there was a significant correlation between pO₂ and loss of excess weight (R=-0.69, p=0.02). No intra- or postoperative complications were observed, and 12 months after surgery BMI decreased to 32.5±2.7 kg/m² (p<0.001) and pCO₂ to 37.9±5.3 mmHg (p=0.05), while pO₂ reached 85.8±6.8 (p<0.001) mmHg.

CONCLUSIONS

In obese patients, the severity of hypoxemia is mainly related to age. The amount of weight reduction, rather than lower baseline BMI values, may justify the significant postoperative pO₂ improvement.

Interferon-gamma releasing assay versus tuberculin skin testing for latent tuberculosis infection in targeted screening programs for high risk immigrants

BACKGROUND

Recent immigrants from developing countries (<2 years since immigration) are at very high risk of active TB disease due to reactivation of latent infections acquired in the country of origin. In industrialized low-incidence TB countries targeted testing programs for high risk groups could allow the detection of latently infected persons who would likely benefit from a course of preventive treatment. In this study we evaluated the tuberculin skin test (TST) and interferon-gamma enzyme-linked immunosorbent assay (QuantiFERON TB-gold in tube, QFT-IT) strategies for TB infection screening programs in recent immigrants from highly endemic countries.

PATIENTS AND METHODS

This is a prospective cross-sectional study. Paired tests performed in 1,130 immigrants attending an outpatient ward, between 2005 and 2007 for any health problem were evaluated by intention-to-treat (ITT) and per-protocol (PP) analysis for efficiency and efficacy of screening program.

RESULTS

Positive TST and QFT-IT were observed in 36.04 versus 29.82% (ITT) and in 45.27 versus 30.22% (PP) respectively. A higher drop-out rate was observed for TST (20.35 vs. 1.33%) (p < 0.0001). Second level assessment was accepted by half of the TST positive patients. Overall agreement rate between 887 paired tests was fair (k = 0.38). Higher k values were observed for higher TB prevalence rate in the country of origin (k = 0.43), for TST induration diameters >20 mM (k = 0.47), in subjects aged 40-50 years (k = 0.41) and in unvaccinated persons (k = 0.40). In a multiple logistic regression model continent of origin, class of TB prevalence in the country of origin and contacts with TB patients were found to be significantly associated with the probability of TST and QFT-IT positive result. Low education levels were associated only to an increased risk of TST positive results.

CONCLUSIONS

The drawback of the TST screening strategy in recent immigrants from highly endemic countries is due to low sensitivity/specificity of the test and to high drop-out rate with an overall significant lowering in strategy efficacy/efficiency. The higher QFT-IT specificity prevents unnecessary overload of the health care system and, although more expensive, might represent a cost-effective alternative to TST in targeted screening programs directed to high risk populations.

The road to zero preventable birth injuries

BACKGROUND

The Seton Family of Hospitals' experience in developing and implementing transformational practices in labor and delivery (L&D) units aimed at reducing the rate of birth trauma at our facilities was previously reported.

METHODS

Seton began its individual perinatal safety effort in earnest in October 2003. The endeavor brought together the four hospitals that offer obstetrical services, resulting in the establishment of an interdisciplinary team. The team meets monthly to develop and monitor best practices that are then shared, executed, and validated by each respective site's perinatal councils.

RESULTS

A 36% reduction in the use of vacuum and forceps (from a frequency of 7.4% to 4.7%) was previously reported; the current rate (fiscal year [FY] 2007-FY 2008 year-to-date; July 1, 2006-December 31, 2007) was 4.1%. The incidence of associated birth trauma decreased to 0% for the last 15 months (ending December 31, 2007). During the first three project years (FY 2004-FY 2006), the average length of stay for infants admitted to the neonatal intensive care unit for birth injury declined by 80% (as compared with the previous three years), from 15.8 to 3.1 days.

DISCUSSION

The perinatal safety team developed processes that have resulted in large and sustained reductions in the rate of serious birth trauma at all obstetric facilities.

Increased formation of 8-iso-prostaglandin F(2alpha) is associated with altered bone metabolism and lower bone mass in hypercholesterolaemic subjects

OBJECTIVES

To investigate the relationship of 8-iso-prostaglandin (PG) F(2alpha) levels, a reliable marker of in vivo oxidative stress and lipid peroxidation, with bone mineral density (BMD), bone turnover markers, osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) in hypercholesterolaemia.

DESIGN

Cross-sectional study.

SETTING

University hospital centre.

METHODS

Serum 8-iso-PGF(2alpha) levels were measured in 173 hypercholesterolaemic subjects and in 152 age- and sex-matched normocholesterolaemic controls. Femoral neck and lumbar spine BMD, serum bone-specific alkaline phosphatase (BAP), osteocalcin (OC), OPG and RANKL levels, as well as urinary levels of C-terminal telopeptides of type I collagen (CTX-I), were also assessed.

RESULTS

Hypercholesterolaemic subjects showed higher (P < 0.0001) serum 8-iso-PGF(2alpha) levels than controls. They also had decreased (P < 0.0001) femoral neck and lumbar spine BMD, and lower (P < 0.0001) serum BAP and OC levels. No significant differences between hypercholesterolaemic and control subjects were found when comparing urinary CTX-I levels, or serum OPG and RANKL levels. In multivariate linear regression analysis, serum 8-iso-PGF(2alpha) was the only negative predictor for femoral neck BMD and serum BAP and OC levels in hypercholesterolaemic subjects. No significant correlation (all P > 0.25) was present between serum 8-iso-PGF(2alpha) levels and urinary CTX-I levels, or serum OPG and RANKL levels, in hypercholesterolaemic subjects.

CONCLUSIONS

We found an association between increased serum 8-iso-PGF(2alpha) levels and lower bone mass and reduced serum BAP and OC concentrations in hypercholesterolaemic subjects. These results would suggest a possible role for oxidative stress in the development of lower bone mass in hypercholesterolaemia.

Eliminating birth trauma at Ascension Health

BACKGROUND

Ascension Health identified perinatal safety as one of eight priorities for action in a systemwide effort to achieve zero preventable injuries and deaths by July 2008.

IMPLEMENTATION

Three alpha sites developed and implemented transformational practices aimed at eliminating preventable birth trauma. Standardized order sets linked to all major areas of obstetrical care were either updated or developed and then tested and incorporated into the work flow of the labor and delivery units. Best practices were shared via team meetings and conference calls. Each site created systems to ensure that evidence-based practices were reliably followed for high-risk conditions associated with perinatal harm, that robust strategies for communication were adopted, and that collaborative practice was promoted among caregivers.

RESULTS

By June 2006, all facilities achieved birth trauma rates that were at or near zero in conjunction with the implementation of these practices.

DISCUSSION

Three alpha sites of differing size, patient demographics, and available resources, using a combined uniform and facility-specific approach, achieved a significant reduction in the incidence of birth trauma. Yet each site adopted unique site-specific processes designed to enhance practice on the basis of unit or institutional culture, market challenge, and/or the prospect for success.

Extended form of a retro-inverso peptide stabilized by beta-sheet unidirectional H-bonds: Crystallographic and NMR evidence

The crystallographic investigation of the retro-inverso peptide Bz-S-gAla-R-mAla-NHPh reveals an extended backbone conformation where the NH groups of the gem-diamino alkyl moiety and the CO groups of the malonyl residue face side by side. This extended conformation, presenting all carbonyls on opposite sides of the NH groups, is stabilized by interstrand H-bonds running in a single direction of the parallel beta-sheets that characterize the crystal packing. These sheets differ from the beta-sheets formed by native amino acids only. (1)H-NMR nuclear Overhauser effect spectroscopy (NOESY) experiments suggest that a conformation similar to that found in the crystal also prevails in dimethylsulfoxide solution. Previous potential energy calculations of gem-diamino alkyl (g) and malonyl (m) Ala residues predicted that extended forms were less stable than the helical ones because of strong electrostatic repulsions between the parallel polar groups. Similar arguments were invoked to give more weight to helical forms of the retro-peptide units in the proposal of packing models of some nylons in their crystalline polar regions. The present findings show that both g and m Ala residues can experience the extended conformation in the beta-sheet aggregation. The energy increase occurring in one strand, due to the parallel orientation of consecutive peptide dipoles, is more than compensated by favorable cooperative interactions among head-to-tail aligned peptide dipoles of facing strands, resulting in the formation of two C==O...H==N H-bonds per residue.

Conformationally constrained analogues of endogenous tripeptide inhibitors of zinc metalloproteinases

Two diastereomeric furan-2-carbonylamino-3-oxohexahydroindolizino[8,7-b]indole carboxylates, highly constrained analogues of endogenous pyroglutamyl tripeptide inhibitors of snake venom endopeptidases, have been prepared as potential inhibitors of adamalysin II and matrix metalloproteinases. They proved to be inactive against adamalysin II and weak inhibitors of gelatinase A, gelatinase B, stromelysin 1 and human neutrophil collagenase. Evaluation of the mode of binding of the (2R,5S,11bR) isomer in the active site of adamalysin II suggests that the decrease of potency may be due to the reorientation of the acylamino chain in three of the heterocyclic nucleus, to a short contact at the entrance of the S'(1) hydrophobic cleft and to the loss of flexibility of the tetracyclic nucleus in the P'(1), P'(2) region of the inhibitor, which prevents optimal arrangement in the S'(1) specificity subsite.

Peptides containing the sulfonamide junction. 2. Structure and conformation of Z-Tau-Pro-D-Phe-NHiPr

The taurine (Tau) containing N-protected pseudotripeptide isopropylamide Z-Tau-Pro-D-Phe-NHiPr (1) has been specifically designed and synthesized as suitable model to test the ability of the sulfonamido group to participate as H-bond acceptor to a type II beta-turn and to get information on the preferred rotameric conformation around the S-N bond and the hybridization state of the nitrogen atom. The present structural investigation reveals that, although the sulfonamide junction is invariably folded in a gauche mode, the beta-turn structure, stabilized by the 4 --> 1 hydrogen bond, is not found in the crystal and the sulfonamido oxygen atoms are not involved in any intra- or intermolecular hydrogen-bond interaction. More than one conformer populates the CDCl(3) solution with only a minor contribution by the expected beta-turn. The Pro nitrogen is significantly pyramidalized and the nitrogen lone pair points in opposite direction to that of the Pro C(alpha)H bond thus adopting R chirality, in an arrangement practically identical to that found in the previously studied homochiral analogue Z-Tau-Pro-Phe-NHiPr.

Two crystal structures of human neutrophil collagenase, one complexed with a primed- and the other with an unprimed-side inhibitor: implications for drug design

Two crystal structures of human neutrophil collagenase (HNC, MMP-8), one complexed with a primed- and the other with an unprimed-side inhibitor, were determined using synchrotron radiation at 100 K. Both inhibitors contain non-hydroxamate zinc-binding functions. The Pro-Leu-L-Trp(P)(OH)(2) occupies the unprimed region of the active site, furnishes new structural information regarding interaction between the catalytic zinc ion and the phosphonate group, and is the only example of occupation of the S(1) subsite of MMP-8 by the bulky tryptophan side chain. The (R)-2-(biphenyl-4-ylsulfonyl)-1,2,3, 4-tetrahydroisochinolin-3-carboxylic acid, a conformationally constrained D-Tic derivative, accommodates its biphenyl substituent into the deep primary specificity S(1)' subsite, inducing a widening of the entrance to this pocket; this modification of the protein, mainly consisting in a shift of the segment centered at Pro217, is observed for the first time in MMP-8 complexes. Cation-aromatic interactions can stabilize the formation of both complexes, and the beneficial effect of aromatic substituents in proximity of the catalytic zinc ion is discussed. The phosphonate group bound to either a primed- or unprimed-side inhibitor maintains the same relative position with respect to the catalytic zinc ion, suggesting that this binding function can be exploited for the design of combined inhibitors assembled to interact with both primed and unprimed regions of the active cleft.

Inhibition of adamalysin II and MMPs by phosphonate analogues of snake venom peptides

Phosphonate analogues of the peptidomimetic N-(Furan-2-yl)carbonyl-Leu-Trp-OH were prepared with the goal of evaluating the effect of phosphonate for carboxylate replacement on binding with snake venom metalloproteinases and MMPs. N-(Furan-2-yl)carbonyl-Leu-L-Trp(P)-(OH)2 showed a 75-fold increase of the inhibiting activity against adamalysin II, a snake venom metalloproteinase structurally related to MMPs and TACE. Both the phosphonate and carboxylate peptidomimetics fit into the active site adopting a retrobinding mode and provide the structural base for a new class of metalloproteinases inhibitors.

Shortened head-up tilt testing potentiated with sublingual nitroglycerin in patients with unexplained syncope

BACKGROUND

Head-up tilt testing is extensively used to determine the vasovagal origin of syncope in patients with otherwise unexplained loss of consciousness, although issues remain regarding the method of the test. The diagnostic value of a shortened head-up tilt test potentiated with sublingual nitroglycerin was assessed in patients with unexplained syncope.

METHODS

Two hundred two patients (mean age 49+/-19 years) with syncope of unknown origin and 34 subjects in a control group (mean age 45+/-17 years) were studied. The patients and the subjects in the control group were tilted upright to 60 degrees for 20 minutes. If syncope did not occur, sublingual nitroglycerin (400 microg) was administered, and observation was continued for 25 more minutes.

RESULTS

During the unmedicated phase syncope occurred in 22 (11%) patients and in one member of the control group. After nitroglycerin was administered, syncope occurred in 119 (59%) patients and in 1 (3%) member of the control group. False-positive response (exaggerated response) was observed in eight (4%) patients and in four (12%) subjects in the control group. The total positivity rate of the test was 70% with a specificity rate of 94%.

CONCLUSIONS

Short-duration head-up tilt test potentiated with sublingual nitroglycerin provides an adequate specificity and positivity rate in patients with unexplained syncope.

Pheochromocytoma crisis caused by contemporary ergotamine, caffeine, and nimesulide administration

Pheochromocytoma is a rare tumor that secretes excess catecholamines. Pheochromocytoma crises may be precipitated by the use of several drugs. This article describes the case of a patient affected by pheochromocytoma in whom multiple organ failure developed after contemporary administration of ergotamine, caffeine, and nimesulide. The patient recovered completely long after surgical intervention.

2 angstrom X-ray structure of adamalysin II complexed with a peptide phosphonate inhibitor adopting a retro-binding mode

The search of reprolysin inhibitors offers the possibility of intervention against both matrixins and ADAMs. Here we report the crystal structure of the complex between adamalysin II, a member of the reprolysin family, and a phosphonate inhibitor modeled on an endogenous venom tripeptide. The inhibitor occupies the primed region of the cleavage site adopting a retro-binding mode. The phosphonate group ligates the zinc ion in an asymmetric bidentate mode and the adjacent Trp indole system partly fills the primary specificity subsite S1'. An adamalysin-based model of tumor necrosis factor-alpha-converting enzyme (TACE) reveals a smaller S1' pocket for this enzyme.

Variations in Tumor Levels of Cis-Platinum through a Course of Fractionated Radiotherapy in Patients with Non-Small Cell Lung Cancer

Aims and background

Radiation has been shown to affect the uptake of micromolecules by the tissues within the radiation fields. We measured tumor drug uptake throughout a course of radiotherapy for stage III non-operable non-small-cell lung cancer (NSCLC).

Patients and Methods

Thirty patients were treated with radiotherapy consisting of 15 fractions of 300 cGy given over 3 weeks. They were divided into groups of 2. At 1.5 hr before a given fraction of radiotherapy, one group was given iv a bolus of 6 mg/m2 CDDP (cis-diamminedichloroplatinum). Between 1.5 and 2 hr after radiotherapy, the patients underwent bronchoscopy, during which a biopsy was taken from the tumor mass. A similar procedure was carried out on a different group of 2 patients at each of the 15 radiotherapy fractions. The amount of platinum in the biopsy sample was measured by atomic absorption spectroscopy and expressed as ng platinum/mg tissue. In another 13 patients, a biopsy was taken before beginning the radiotherapy, and they served as controls.

Results

The quantity of platinum/g of tissue in the patients was 11 ± 4.4 ng/mg tissue. During the course of fractionated radiotherapy, the quantity of platinum/g of tumor varied considerably between radiotherapy fractions. Maximum uptake was at fractions 8 and 9 (92 ng platinum/mg tissue) with the minima during the first few fractions and at fractions 10, 11 and 12 (an average 20 ng platinum/mg tissue).

Conclusions

The cyclical variations in the uptake of CDDP by the tumor tissue during the protracted course of fractionated radiotherapy are probably due to the well-known effects of radiation on vascular function and capillary permeability. The results may have implications for future clinical protocols involving chemo- and radiotherapy for the treatment of the disease.

Synthesis, conformation, and biological activity of two fMLP-OMe analogues containing the new 2-[2'-(methylthio)ethyl]methionine residue

The new C alpha-tetrasubstituted alpha-amino acid residue 2-[2'-(methylthio)ethyl]methionine (Dmt) has been introduced into the reference chemotactic tripeptide HCO-Met-Leu-Phe-OMe (fMLP-OMe) in place of the leucine or methionine, respectively. The biological activity of the new analogues [Dmt2]fMLP-OMe (2) and [Dmt1]fMLP-OMe (3) has been determined; whereas 2 is active toward human neutrophils, stimulating directed migration, superoxide anion generation, and lysozyme release, 3 results practically inactive in all tested assays. A conformational analysis on 2 and 3 has been performed in solution by using ir absorption and 1H-nmr. The conformation of 2 was also examined in the crystal by x-ray diffraction methods. Both 2 and 3 adopt fully extended conformation in correspondence with the Dmt residue. Biological and conformational results are discussed and compared with related previously studied models.

[Unstable angina in coronary intensive care units without hemodynamics: is admissible a strategy limiting the indications for coronarography?]

In coronary care units (CCU) without cardiac catheterization facilities, coronary angiography is rarely carried out when a successful medical treatment in the acute phase of unstable angina has been obtained. However, the unstable angina still has an uncertain prognosis when the remission of pain is obtained with drugs. This study presents a follow-up of 147 consecutive patients (aged 66.8 +/- 10.4 years) admitted to our CCU in 1991 and 1992 for unstable angina; 33 of them (22.4%) were in Braunwald class I. 2 (1.4%) in class II and 112 (76.2%) in class III. The patients were treated according to the usual therapy protocols and class III patients received i.v. heparin. In selected cases we used thrombolysis (10 patients) and intra-aortic balloon pump (5 patients). During hospitalization 1 patient died (0.7%), 5 patients (3.4%) suffered an acute myocardial infarction and 9 patients (6.1%) had angina. Stabilization of unstable angina was achieved in 132 patients (89.9%): in 113 (76.8%) during the first 48 hours, and in 19 (12.9%) later. Coronary angiography was carried out in non-stabilized patients and in 46 (34.8%) of the 132 with successful treatment (Group I). Eighty-six patients, without indication to coronary angiography were discharged in medical therapy (Group II). During the follow-up (mean of 15.0 +/- 9.0 months) Group I 10 patients (18.2%) had cardiac events (death, myocardial infarction, or recurrent angina) vs 26 of Group II (p < 0.05). In Group I coronary angiography together with clinical criteria of high risk allowed the identification of candidates to coronary revascularization (61.8% of Group I patients while). These data show that the initial success of treatment during the acute phase of unstable angina should not be considered as a favourable prognostic index. Coronary angiography appears to be indicated for clinical evaluation and therapeutical decision.

Modified chemotactic peptides: synthesis, conformation, and activity of HCO-Thp-Ac6c-Phe-OMe

HCO-Thp-Ac6c-Phe-OMe (3) has been synthesized as a new analogue of the prototypical chemotactic agent HCO-Met-Leu-Phe-OMe (fMLP-OMe). Compound 3 contains 4-aminotetra-hydrothiopyran-4-carboxylic acid (Thp) and 1-aminocyclohexane-1-carboxylic acid (Ac6c) as achiral, conformationally restricted mimics of Met and Leu, respectively. In the crystal, the formyltripeptide adopts an helical conformation at the Thp and Ac6c residues, of the type alpha R and alpha L, respectively, whereas the C-terminal phenylalanine is quasi-extended. A system of two consecutive gamma-turns, centered at the first two residues, better explains the nmr data as compared with an alternative beta-turn structure. The conformation of the new analogue 3 is compared with those of two related peptides containing Thp as N-terminal residue. The biological activity of 3 has been determined on human neutrophils and compared to that of the previously studied model [Ac6c2] fMLP-OMe. While the above analogue is highly active in the superoxide anion production, the new tripeptide 3 is practically unable to elicit any of the tested biological activities.

Substituent effects on the enantioselective retention of anti-HIV 5-aryl-delta 2-1,2,4-oxadiazolines on R,R-DACH-DNB chiral stationary phase

A series of racemic 3-phenyl-4-(1-adamantyl)-5-X-phenyl- delta 2-1,2,4-oxadiazo lines (PAdOx) were directly resolved by HPLC using a Pirkle-type stationary phase containing N,N'-(3,5-dinitrobenzoyl)-1(R),2(R)-diaminocyclohexane as chiral selector. The more retained enantiomers have S configuration, as demonstrated by X-ray crystallography and circular dichroism measurements. The influence of aromatic ring substituents on enantioselective retention was quantitatively assessed by traditional linear free energy-related (LFER) equations and comparative molecular field analysis (CoMFA). In good agreement with previous findings, the results from this study indicate that the increase in retention (k') is favoured mainly by the phi-basicity and the hydrophilicity of solute, whereas enantioselectivity (alpha) can be satisfactorily modeled by electronic and bulk parameters or CoMFA descriptors. The LFER equations and CoMFA models gave helpful insights into chiral recognition mechanisms.

Relation between diastolic perfusion time and coronary artery stenosis during stress-induced myocardial ischemia

BACKGROUND

Experimental studies have demonstrated that during stress-induced myocardial ischemia, coronary obstruction and diastolic perfusion time are factors that limit subendocardial perfusion and correlate to degree of myocardial dysfunction. The relation between these two factors has not yet been investigated in humans. The aim of the present study was to assess the relation between diastolic perfusion time and degree of coronary stenosis during different types of stress tests.

METHODS AND RESULTS

Nine patients with isolated and proximal stenosis of the left anterior descending coronary artery were selected. Patients underwent three different randomized stress tests (upright, supine bicycle stress test, and transesophageal atrial pacing). Diastolic perfusion time, heart rate (RR interval), and systolic and diastolic pressures were measured during the test and at the ischemic threshold (0.1-mV ST-segment depression). Angiographic measurements of coronary stenosis were evaluated by quantitative coronary angiography. At the ischemic threshold, significant differences among tests were found in heart rate (P < .05), systolic pressure (P < .001), and diastolic pressure (P < .05). In each stress test, diastolic perfusion time at the ischemic threshold was closely correlated with minimal stenosis diameter (r = .97; P < .001) and percent diameter stenosis (r = .92; P < .001) with no difference among the tests. In contrast, heart rate, rate-pressure product, and time to ischemic threshold were not significantly correlated with percent diameter stenosis and minimal stenosis diameter. No significant correlation was observed at the ischemic threshold between diastolic perfusion time and corresponding values of heart rate, despite the close correlation at rest (r = .95; P < .001).

CONCLUSIONS

Despite differences in associated hemodynamic responses to various stress tests, a close relation exists between stenosis severity and diastolic perfusion time at the onset of stress-induced myocardial ischemia. Therefore, diastolic perfusion time at the ischemic threshold may be an indirect estimate of the hemodynamic significance of coronary stenosis.

For-Met-Lys-Phe-For-Met-Lys-Phe-: a new cyclic analogue of the chemotactic formylpeptides

As a continuation of the studies on chemotactic N-formylpeptides, we report here the synthesis and activity of a new cyclic analogue of the prototypical ligand For-Met-Leu-Phe-OMe. The new compound For-Met-Lys-Phe-For-Met-Lys-Phe- (4) contains a 20-membered cyclic moiety made up of a dimeric -Lys-Phe- sequence in which For-Met is attached to each Lys alpha-NH2 and hence remains outside the ring. The conformation in the crystal of the cyclic precursor of 4, namely Boc-Lys-Phe-Boc-Lys-Phe- (2) and the activity of the structurally related linear analogue For-Met-Lys(Z)-Phe-OBzl (6), have also been examined. The new analogues 4 and 6 are active as chemoattractants, secretagogues, and superoxide anion generating agents, when tested on human neutrophils. The structure-activity relationship is discussed and related to that of a previously studied cyclic model.

X-ray crystal structure, partitioning behavior, and molecular modeling study of piracetam-type nootropics: insights into the pharmacophore

To detect possible molecular determinants of amnesia-reverting activity, the conformational properties of a number of rigid and flexible piracetam-type cognition enhancers have been assessed by X-ray diffraction, NMR spectroscopy, and ab initio and high-temperature-quenched molecular dynamics (QMD) calculations. The structures of the preferred conformers in solution derived from 1H-NMR spectral analysis were in good agreement with those found by QMD calculations. Interestingly, the calculation of the average molecular lipophilicity potential on the water-accessible surface of the selected conformers was helpful in interpreting the partitioning behavior observed by measuring octanol-water partition coefficients and capacity factors in reversed-phase high-performance liquid chromatography. While lipophilicity does not play a relevant role, the distance between polar groups, accounted for by the distance between carbonyl oxygens, emerges as a factor, among others, which should influence the amnesia-reversal activity of piracetam-type nootropics.

Modified chemotactic peptides: synthesis, conformation, and biological activity of For-Thp-Leu-delta ZPhe-OMe

For-Thp-Leu-delta ZPhe-OMe (2), an analogue of the chemotactic tripeptide For-Met-Leu-Phe-OMe, containing 4-aminotetrahydrothiopyran-4-carboxylic acid (Thp) and (Z)-2,3-didehydrophenylalanine (delta ZPhe) as achiral, conformationally restricted mimics of Met and Phe, respectively, has been synthesized. In the crystal the new formyltripeptide adopts a type I beta-turn conformation stabilized by a weak H bond between the formylic oxygen and the delta ZPhe NH. 1H-nmr analysis based on NH solvent accessibility and nuclear Overhauser effect experiments suggests that the beta-turn is not preferred in CDCl3 solution where a gamma-turn, centered at the Thp residue, prevails. The biological activity of 2 has been determined on human neutrophils and compared to that of previously studied analogues. The tripeptide 2 is practically unable to elicit superoxide anion production and lysozyme release, while slight, but not statistically significant activity was induced in chemotaxis. The role of the orientation of the aromatic ring with respect to the backbone adjacent atoms is discussed.

[Right atrial metastasis as an initial clinical manifestation of adenocarcinoma of the colon]

We report the case of a young woman suffering from colonic mucinous adenocarcinoma with the unusual clinical presentation as a right atrial metastasis. The tumor was successfully resected, and after histopathological characterization, the primary lesion was searched for and discovered. The tumor had the clinical appearance and echocardiographic pattern of a pedunculated atrial myxoma. The aspects of echo-patterns useful for differential diagnosis are discussed.