Autoantibodies detection in patients affected by autoimmune retinopathies

OBJECTIVE

Autoimmune retinopathies (ARs) encompass a spectrum of immune diseases that are characterized by the presence of autoantibodies against retinal proteins in the bloodstream. These autoantibodies (AAbs) lead to a progressive and sometimes rapid loss of vision. ARs commonly affect subjects over 50 years of age, but also rare cases of kids under 3 years of age have been reported.

PATIENTS AND METHODS

In this study, 47 unrelated Caucasian patients were enrolled. All subjects showed negative cancer diagnoses and negative results in their genetic screenings. We studied 8 confirmed retinal antigens using Western blotting analysis, with α-enolase followed by carbonic anhydrase II being the two most frequently found in the patients' sera.

RESULTS

Nineteen patients were positive (40.4%), thirteen uncertain (27.7%), and fifteen were negative (31.9%). Their gender did not correlate with the presence of AAbs (p=0.409).

CONCLUSIONS

AAbs are responsible for retinal degeneration in some cases, while in others, they contribute to exacerbating the progression of the disease; however, their detection is crucial to reaching a better diagnosis and developing more effective treatments for these conditions. Moreover, finding good biomarkers is important not only for AR monitoring and prognosis, but also for helping with early cancer diagnosis.

Knowledge and Attitudes towards HIV and HCV among the Population Attending the Fast-Track Cities Mobile Unit in Brescia, Italy

The Infectious and Tropical Diseases Department of the University of Brescia organized free rapid screening tests for HIV and HCV as part of the Fast-Track City commitment. A cross-sectional study was conducted, consisting of an anonymous multiple-choice questionnaire that was administered to individuals who underwent the screening or consultation. The study aimed to compare knowledge and attitudes towards HIV and HCV between age groups (18-40 vs. >40) and sexual orientations (heterosexual vs. LGBTQ+). Overall, 333 questionnaires were completed. Overall, only 107 (32%) of respondents knew how HIV is transmitted. Major differences were shown between different age groups, where people under the age of 40 had a significantly higher correct response rate than people over 40 (n = 101; 39% versus n = 6; 7.8%, p < 0.00001). Similarly, almost half of LGBTQI+ people (n = 28; 44.4%) gave the correct answer, versus 30% (n = 79) of heterosexuals (p = 0.0359). Only 9.6% of the population demonstrated high levels of knowledge for both HIV and HCV. Our study highlights that misconceptions about HIV and HCV should be addressed in prevention and education programs, whose target should also be specific populations.

Risk factors of adolescent exposure to violence in Burkina Faso

BACKGROUND

Globally violence against children and adolescents is a significant public health problem. Since children rely on family for early learning and socialization, evidence of the factors associated with exposure to violence within households may inform the development of policies and measures to prevent violence and aid the victims of violence. This study examines the risk and protective factors associated with adolescents' exposure to violence at home and how these differ by gender and age in four regions of Burkina Faso.

MATERIALS AND METHODS

We used data from the baseline survey of the Child-Sensitive Social Protection Programme (CSSPP) conducted in four regions of Burkina Faso. The CSSPP is a cash transfer programme accompanied by complimentary nutrition, and water and sanitation interventions to address multidimensional child poverty. We employed bivariate and multivariable regression analysis on a sample of 2222 adolescents aged 10-19 to explore the risk and protective factors associated with exposure to violence.

RESULTS

Results show that exposure to psychological violence (22.7%) was more common within the households when compared to physical violence (9.1%). Adolescent girls reported more exposure to physical violence while boys reported more exposure to psychological violence. Significant risk factors associated with the likelihood of exposure to violence among girls are orphanhood, living in a household receiving safety nets and living in a Muslim-majority community. Among boys, age, school attendance, disability, a household receiving safety nets, sharing a household with a depressed individual, and living in a Muslim-majority community, were associated with exposure to violence.

CONCLUSIONS

These gender-specific findings highlight the importance of family background characteristics and can be used to inform and strengthen the targeting of vulnerable children and adolescents in interventions aimed at reducing exposure to violence against children.

Characteristics of the population with mild COVID-19 symptoms eligible for early treatment attended in a single center in Northern Italy

After more than two years from the first COVID-19 detected case in Brescia, Northern Italy, monoclonal antibodies and antiviral therapy aimed at early treatment of mild COVID-19 in patients at risk of progression and of hospitalization has been approved in Italy. Here we report the characteristics of the population eligible for the COVID-19 early treatments at our COVID-19 Early Therapy Unit of the Infectious Diseases Department of the ASST Spedali Civili of Brescia, with the aim to evaluate the characteristics of the foreign and native groups. Up to March the 31st, 2022, a total of 559 patients were referred to our Unit for COVID-19 early treatment, where 7.6% were foreigners, a group significantly younger than natives (p<0.05). Particular differences are noticed between the native and the foreign population, where people aged > 65 years old were significantly more frequent among italians (39.7% vs 16.3%, p<0.01), while primary or acquired immunodeficiencies were more frequent in foreigners (55.8% vs 38.9%, p=0.03). Substantial differences are noted between native and foreign populations, where 14% and 26% (p<0.05) respectively have never been vaccinated for COVID-19. Overall, 71% of the referred patients received an early treatment for mild COVID-19, with no differences between the two groups. Overall, on day 28 after treatment, 23 (4%) patients had been hospitalized due to COVID-19 related complications and four died (0,7%), no one was foreigner. In conclusion, while the treatment offered for mild COVID-19 appears to be rather uniform between the native and the foreign populations, some differences, especially in preventive vaccination COVID-19, must be taken into account.

Effects of circadian rhythm disruption on retinal physiopathology: Considerations from a consensus of experts

The circadian rhythms originate within the organism and synchronize with cyclic fluctuations in the external environment. It has been demonstrated that part of the human genome is under control of the circadian clock and that a synchronizer that helps to maintain daily rhythms is Melatonin, a neuro-hormone primarily synthesized by the pineal gland during the night. The chronic disruption of circadian rhythm has been linked to many conditions such as obesity, metabolic syndrome, type 2 diabetes, cancer, and neurodegenerative diseases. Studies in the mice showed that the disruption of the retinal circadian rhythm increases the decline during the aging of photoreceptors, accelerating age-related disruption of cone cell structure, function, and viability and that the melatonin receptor deletion seems to influence the health of retinal cells, speeding up their aging. In conclusion, preserving the circadian rhythms could be to add to the prevention and treatment of age-related degenerative retinal diseases, and although additional studies are needed, melatonin could be a valid support to favor this “chronoprotection action”.

Carcinosarcoma of the Nasal Septum: A Case Report and Review of the Literature

We report a case of a 62-year-old man with epistaxis and right-sided nasal obstruction. Nasal endoscopy revealed an exophytic mass arising from the anterior septum that extended posteriorly to the osteo-meatal complex. Excision with endoscopic sinus surgery was performed. Carcinosarcoma was diagnosed based on histopathology and immunohistochemical studies. The patient declined surgery and opted for chemoradiation therapy for the residual tumor. Six weeks after completion of the treatment, clinical resolution of the right nasal mass was noted. Carcinosarcomas are rare and rapidly growing tumors that have a high recurrence rate and are associated with poor patient prognosis. This report emphasizes the need for patients with prolonged nasal obstruction and epistaxis to consult otolaryngologists and undergo nasal endoscopy for definitive diagnosis and appropriate treatment.

Thumb to spinous process is a false metric for glenohumeral internal rotation

Background

The measurement of internal rotation by noting the maximal vertebral level reached by the patient's thumb behind their back is an established physical examination technique, as outlined in the American Shoulder and Elbow Surgeons Shoulder Assessment Form.7 The purpose of the present study is to correlate real-time glenohumeral internal rotation with thumb to spinous process movement to determine the accuracy of the technique.

Methods

Healthy volunteers with no previous history of shoulder injury or symptoms were recruited from the local medical school population. Ultrasound probe was placed over the anterolateral shoulder, and relevant anatomy was identified. Internal rotation was evaluated by measuring displacement of the peak of the medial aspect of the bicipital groove relative to the anterior glenoid rim with the arm held in defined positions of progressively increasing internal rotation. The difference in displacement between arm positions was calculated and recorded.

Results

A total of 20 participants (11 women/9 men, aged 22-42 years) were recruited for measurement. A mixed-model repeated-measures analysis of variance was used. The most significant differences in displacement, and therefore internal rotation, were observed between the neutral and anterior superior iliac spine (0.21 ± 0.39 mm, P= .0269) and between the anterior superior iliac spine and peak iliac crest (0.26 ± 0.44 mm, P= .0163). After the peak iliac crest, there was no further statistically significant change in rotation.

Conclusion

The present study suggests that most glenohumeral internal rotation occurs before reaching the arm behind the back. Although not directly studied, this supports the notion that the maximal vertebral level reached involves an interplay of various joint motions. While the thumb to spinous process maneuver remains a functional evaluation, our results suggest a different examination technique be used to more accurately test glenohumeral internal rotation.

POS1393 QUANTITATIVE AUTOFLUORESCENCE FINDINGS IN PATIENTS UNDERGOING HYDROXYCHLOROQUINE TREATMENT

Background:

Hydroxychloroquine (HCQ) is a relatively safe and effective drug widely used as primary or adjunctive treatment for several rheumatological and dermatological disorders1. HCQ modulates immune response through several mechanisms and has a tropism for pigmented ocular tissues, particularly retinal pigment epithelium (RPE)2. Its accumulation within RPE cells can lead to sight threatening retinal toxicity, with bull’s eye maculopathy (BEM) representing its advanced phenotype. 3 Quantitative Auto-Fluorescence (qAF) is an imaging modality that allows the measurement of retinal auto-fluorescence following short-wavelength light (488nm) excitation of retinal fluorophores (lipofuscin). 4 Two recent studies have focused on qAF values in patients treated with HCQ 5,6. In both cases qAF was increased in eyes with BEM. Furthermore, Reichel et al.6 were able to detect increased values of qAF in patients without BEM as early as 6 months after the start of HCQ treatment using an experimental imaging analysis procedure.

Objectives:

To measure quantitative autofluorescence (qAF) in patients under treatment with hydroxychloroquine (HCQ) with no apparent signs of retinal toxicity and to compare it with that of untreated subjects.

Methods:

Consecutive patients at risk for the development of HCQ retinal toxicity (duration of treatment >5 years or daily HCQ dose >5 mg/kg of actual body weight (ABW) and/or renal insufficiency)7 but no alterations on Spectral Domain - Optical Coherence Tomography, Short-Wavelength Autofluorescence and 10-2 Visual Field examination were recruited. Healthy subject matched by age and sex were also enrolled in the study. All subjects underwent qAF measurements in one eye. Images were analyzed using the conventional qAF grid by Delori calculating the qAF of 8 sectors of the intermediate ring and the mean of those values (qAF8).

Results:

Thirty-nine patients treated with HCQ (38 females, mean age 52,1 ± 8,6 years) and 39 untreated subjects (38 females, mean age 51,2 ± 8,6 years). In both HCQ patients and untreated subjects, qAF8 was positively correlated with age (p=0.004) (Figure 1). Although HCQ patients showed a higher mean qAF8 compared to untreated subjects (294,7 ±65,3 vs 268,9 ± 57,5), the difference was not significant (p=0.068). HCQ patients showed significantly higher mean qAF values in the inferior-temporal, inferior and inferior-nasal sectors of the intermediate ring of qAF grid compared to untreated subjects (all p<0.05).

Figure 1.

Visual representation of a model predicting the standardized qAF values as influenced by age and HCQ daily dose/ABW, calculated for a treatment duration of 15 years.

Conclusion:

These results suggest a possible preclinical increase of qAF values in inferior parafoveal sectors probably induced by HCQ exposure. Further studies are required to improve our understanding of preclinical stages of HCQ retinopathy and the possible role of qAF in the HCQ toxicity screening.

References:

[1]Haładyj, E., Sikora, M., Felis-Giemza, A. & Olesińska, M. Antimalarials - are they effective and safe in rheumatic diseases? Reumatologia56, 164–173 (2018).

[2]Rosenthal, A. R., Kolb, H., Bergsma, D., Huxsoll, D. & Hopkins, J. L. Chloroquine retinopathy in the rhesus monkey. Invest. Ophthalmol. Vis. Sci.17, 1158–1175 (1978).

[3]Modi, Y. S. & Singh, R. P. Bull’s-Eye Maculopathy Associated with Hydroxychloroquine. N. Engl. J. Med.380, 1656 (2019).

[4]Sparrow, J. R., Duncker, T., Schuerch, K., Paavo, M. & de Carvalho, J. R. L. J. Lessons learned from quantitative fundus autofluorescence. Prog. Retin. Eye Res.74, 100774 (2020).

[5]Greenstein, V. C. et al. Quantitative Fundus Autofluorescence in HCQ Retinopathy. Invest. Ophthalmol. Vis. Sci.61, 41 (2020).

[6]Reichel, C. et al. Quantitative Fundus Autofluorescence in Systemic Chloroquine/Hydroxychloroquine Therapy. Transl. Vis. Sci. Technol.9, 42 (2020).

[7]Yusuf, I. H., Sharma, S., Luqmani, R. & Downes, S. M. Hydroxychloroquine retinopathy. Eye (Lond).31, 828–845 (2017).

Disclosure of Interests:

Salvatore Parrulli: None declared, Mariano Cozzi Grant/research support from: Bayer, Nidek, Zeiss, Matteo Airaldi: None declared, Francesco Romano: None declared, Francesco Viola: None declared, Piercarlo Sarzi-Puttini: None declared, Giovanni Staurenghi Grant/research support from: Heidelberg Engineering (C), QuantelMedical (C), Centervue (C), Carl Zeiss Meditec (C), Alcon (C), Allergan (C), Bayer (C), Boheringer (C), Genentech (C), GSK (C),Novartis (C), and Roche (C), Optos (F), Optovue (F) and Centervue (F), Alessandro Invernizzi Grant/research support from: Novartis (C), Bayer (C)

Contributed Review: Review of thermal methods for space charge measurement

The space charge accumulation phenomenon has garnered great interest over the last two decades because of the increased use of direct current in high voltage electrical systems. In this context, a significant relevance has been achieved by the thermal methods, used for solid dielectrics. This paper presents a review of this non-destructive measurement system used for the measurement of space charge. The thermal pulse method, the thermal step method, and the laser intensity modulation method are described. For each configuration, the principle of operation, the thicknesses analyzed, and the spatial resolution are described, reporting also the main related applications.

Co-evolution of hydrological components under climate change scenarios in the Mediterranean area

The Mediterranean area is historically characterized by high human pressure on water resources. Today, while climate is projected to be modified in the future, through precipitation decrease and temperature increase, that jointly and non-linearly may affect runoff, concerns about water availability are increasing. For these reasons, quantitative assessment of future modifications in the mean annual water availability are important; likewise, the description of the future interannual variability of some hydrological components such as runoff and evapotranspiration are highly wished for water management and ecosystems dynamics analyses. This study investigates at basin spatial scale future runoff and evapotranspiration, exploring their probability density functions and their interdependence as functions of climatic changes. In order to do that, a parsimonious conceptual lumped model is here used. The model is forced by different future climate scenarios, generated through a weather generator based on a stochastic downscaling of an ensemble of General Circulation Models (GCMs) realizations. The use of the adopted hydrological model, under reliable stochastic future climate scenarios, allows to project future values of evapotranspiration and runoff in a probabilistic framework and, at the same time, the evaluation of their bivariate frequency distributions for changes through the Multivariate Kernel Density Estimation method. As a case study, a benchmark Mediterranean watershed has been proposed (Imera Meridionale, Italy). Results suggest a radical shift and shape modification of the annual runoff and evapotranspiration probability density functions. Possible implications and impacts on water resources management are here addressed and discussed.

AAV-mediated photoreceptor transduction of the pig cone-enriched retina

Recent success in clinical trials supports the use of adeno-associated viral (AAV) vectors for gene therapy of retinal diseases caused by defects in the retinal pigment epithelium (RPE). In contrast, evidence of the efficacy of AAV-mediated gene transfer to retinal photoreceptors, the major site of inherited retinal diseases, is less robust. In addition, although AAV-mediated RPE transduction appears efficient, independently of the serotype used and species treated, AAV-mediated photoreceptor gene transfer has not been systematically investigated thus so far in large animal models, which also may allow identifying relevant species-specific differences in AAV-mediated retinal transduction. In the present study, we used the porcine retina, which has a high cone/rod ratio. This feature allows to properly evaluate both cone and rod photoreceptors transduction and compare the transduction characteristics of AAV2/5 and 2/8, the two most efficient AAV vector serotypes for photoreceptor targeting. Here we show that AAV2/5 and 2/8 transduces both RPE and photoreceptors. AAV2/8 infects and transduces photoreceptor more efficiently than AAV2/5, similarly to what we have observed in the murine retina. The use of the photoreceptor-specific rhodopsin promoter restricts transgene expression to porcine rods and cones, and results in photoreceptor transduction levels similar to those obtained with the ubiquitous promoters tested. Finally, immunological, toxicological and biodistribution studies support the safety of AAV subretinal administration to the large porcine retina. The data presented here on AAV-mediated transduction of the cone-enriched porcine retina may affect the development of gene-based therapies for rare and common severe photoreceptor diseases.

Interactions of oxidosqualene cyclase (Erg7p) with 3-keto reductase (Erg27p) and other enzymes of sterol biosynthesis in yeast

In Saccharomyces cerevisiae and Candida albicans, two enzymes of the ergosterol biosynthetic pathway, oxidosqualene cyclase (Erg7p) and 3-keto reductase (Erg27p) interact such that loss of the 3-keto reductase also results in a concomitant loss of activity of the upstream oxidosqualene cyclase. This interaction wherein Erg27p has a stabilizing effect on Erg7p was examined to determine whether Erg7p reciprocally has a protective effect on Erg27p. To this aim, three yeast strains each lacking the ERG7 gene were tested for 3-ketoreductase activity by incubating either cells or cell homogenates with unlabeled and radiolabeled 3-ketosteroids. In these experiments, the ketone substrates were effectively reduced to the corresponding alcohols, providing definitive evidence that oxidosqualene cyclase is not required for the 3-ketoreductase activity. This suggests that, in S. cerevisiae, the protective relationship between the 3-keto reductase (Erg27p) and oxidosqualene cyclase (Erg7p) is not reciprocal. However, the absence of the Erg7p, appears to affect other enzymes of sterol biosynthesis downstream of lanosterol formation. Following incubation with radiolabeled and non-radiolabeled 3-ketosteroids we detected differences in hydroxysteroid accumulation and ergosterol production between wild-type and ERG7 mutant strains. We suggest that oxidosqualene cyclase affects Erg25p (C-4 sterol oxidase) and/or Erg26p (C-3 sterol dehydrogenase/C-4 decarboxylase), two enzymes that, in conjunction with Erg27p, are involved in C-4 sterol demethylation.

Design and characterization of supersonic nozzles for wide focus laser-plasma interactions

In this work we optimize the contour of supersonic nozzles to produce long and stable gas jets suitable to be used in loose focus laser-plasma applications. The nozzle design method takes into account the inclusion of a boundary layer that increases the length of the usable gas jet. Two 8 mm supersonic nozzles were characterized, one with a Mach number of 3 and another with a Mach number of 6, using a Mach-Zehnder interferometer performed with a He:Ne 4 cm expanded laser beam. The experimental results confirm that the inclusion of the boundary layer produces an 8 mm constant longitudinal density profile for the nozzle with a Mach number of 6 (NM6) and a 4.5 mm constant longitudinal density profile for the nozzle with a Mach number of 3 (NM3).

Combining photodynamic therapy and feeder vessel photocoagulation: A pilot study

Patients receiving photodynamic therapy (PDT) with verteporfin (Visudyne, Novartis AG), a new treatment for subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) and pathologic myopia, should be scheduled for follow-up every 12 weeks (+/-2 weeks) after the initial treatment. However, important data from clinical practice and from small series studies suggest that this period between treatment may be too long for some patients. In this pilot study we explore the safety and the possibility of improving the extent and duration of PDT benefit using feeder vessel treatment (FVT). This study suggests that the combination of verteporfin therapy and FVT is a safe procedure; it also suggests a possibility for prolonging the effect of verteporfin therapy.

Infliximab for pediatric ulcerative colitis: a retrospective Italian multicenter study

BACKGROUND

Infliximab (IFX), the chimeric anti TNFalpha antibody, an established treatment for Crohn's disease in adults and in children, is used less frequently in ulcerative colitis (UC).

AIM OF THE STUDY

To report the clinical course of pediatric patients with active UC receiving IFX.

PATIENTS AND METHODS

Charts of 22 patients were reviewed (13 male, 9 female): 4 with a severe UC attack refractory to systemic corticosteroids (CS); 18 with a protracted course, of which 16 CS-dependent and 2 CS-resistant. The baseline therapeutic program consisted of 3 consecutive intravenous infusions (0, 2, 6 weeks) of IFX (5 mg/kg), followed by a retreatment schedule (infusion every 8 weeks); azathioprine (AZA) was administered chronically in all. Clinical evaluation was done with the Lichtiger Colitis Activity Index (LCAI). Follow-up was performed until week 54. LCAI >/= 9 was considered treatment failure; a LCAI </= 2 was consistent with remission.

RESULTS

All 22 patients began the study with a LCAI > 9: 12 had a full response and were on remission at week 54 and did not receive CS (8 on IFX re-treatment and AZA, 4 on AZA alone); 6 had a partial response; 4 were non responders. Colectomy was performed in 7 patients, beyond the period of the acute attack in all but one.

CONCLUSIONS

In children with severe ulcerative colitis IFX is a valuable treatment for inducing remission, avoiding emergency colectomy; retreatment may be offered to maintain remission.

Time-domain optimized near-field estimator for ultrasound imaging: initial development and results

For nearly four decades, adaptive beamforming (ABF) algorithms have been applied in RADAR and SONAR signal processing. These algorithms reduce the contribution of undesired off-axis signals while maintaining a desired response along a specific look direction. Typically, higher resolution and contrast is attainable using adaptive beamforming at the price of an increased computational load. In this paper, we describe a novel ABF designed for medical ultrasound, named the Time-domain Optimized Near-field Estimator (TONE). We performed a series of simulations using synthetic ultrasound data to test the performance of this algorithm and compared it to conventional, data independent, delay and sum beamforming (CBF) method. We also performed experiments using a Philips SONOS 5500 phased array imaging system. CBF was applied using the default parameters of the Philips scanner, whereas TONE was applied on per channel, unfocused data using an unfocused transmit beam. TONE images were reconstructed at a sampling of 67 microm laterally and 19 microm axially. The results obtained for a series of five 20-microm wires in a water tank show a significant improvement in spatial resolution when compared to CBF. We also analyzed the performance of TONE as a function of speed of sound errors and array sparsity, finding it robust to both.

In-vivo diffusing-wave-spectroscopy measurements of the ocular fundus

We present what is to our knowledge the first observation of a diffusing-wave-spectroscopy signal recorded in-vivo on the ocular fundus. A modified ophthalmic microscope was developed which can acquire diffusing-wave-spectroscopy signal from the eye fundus. The diffusing-wave-spectroscopy signal was recorded in-vivo on a rabbit eye during transpupillary thermotherapy. Experimental results show the ability of the system to detect motion of the scattering sites in the ocular fundus layers during laser thermal heating.

Access of the substrate to the active site of squalene and oxidosqualene cyclases: comparative inhibition, site-directed mutagenesis and homology-modelling studies

Substrate access to the active-site cavity of squalene-hopene cyclase from Alicyclobacillus acidocaldarious and lanosterol synthase [OSC (oxidosqualene cyclase)] from Saccharomyces cerevisiae was studied by an inhibition, mutagenesis and homology-modelling approach. Crystal structure and homology modelling indicate that both enzymes possess a narrow constriction that separates an entrance lipophilic channel from the active-site cavity. The role of the constriction as a mobile gate that permits substrate passage was investigated by experiments in which critically located Cys residues, either present in native protein or inserted by site-directed mutagenesis, were labelled with specifically designed thiol-reacting molecules. Some amino acid residues of the yeast enzyme, selected on the basis of sequence alignment and a homology model, were individually replaced by residues bearing side chains of different lengths, charges or hydrophobicities. In some of these mutants, substitution severely reduced enzymatic activity and thermal stability. Homology modelling revealed that in these mutants some critical stabilizing interactions could no longer occur. The possible critical role of entrance channel and constriction in specific substrate recognition by eukaryotic OSC is discussed.

Carnitine deficiency in patients with coeliac disease and idiopathic dilated cardiomyopathy

BACKGROUND AND AIMS

Idiopathic dilated cardiomyopathy (IDCM) and coeliac disease (CD) are two pathological conditions which may lead, by different mechanisms, to malabsorption of various micronutrients, including carnitine, active in cardiac metabolism. The aim of the present investigation was primarily to evaluate differences in serum concentrations of total carnitine between IDCM patients and patients with IDCM associated with CD and then also to evaluate, in the latter, the effect of a gluten-free diet on serum concentrations of total carnitine.

METHOD AND RESULTS

Serum carnitine was determined by enzymatic spectrophotometric assay in three groups of individuals: group A, 10 patients (5 males, 5 females), mean age 46.5+/-10.8 years, presenting isolated IDCM; group B, 3 patients (2 males, 1 female), mean age 34+/-8 years, with IDCM+CD; and group C, 10 healthy subjects (5 males, 5 females), mean age 38.6+/-11.1 years. All patients with IDCM belonged to class NYHA I-II. Mean concentrations of total serum carnitine in the group of patients with isolated IDCM (group A) were found to be lower than in the controls (group C). The concentrations in patients with IDCM associated with CD (group B) were lower than in the control group and also lower than in the isolated IDCM (group A). After 2 years on a gluten-free diet, patients presenting IDCM associated with CD showed a progressive increase in mean serum carnitine levels compared to values observed prior to the diet.

CONCLUSIONS

Patients presenting IDCM associated with CD show a greater decrease in serum total carnitine levels than patients presenting the isolated form of IDCM. A gluten-free diet, in these patients, leads to a progressive increase in serum levels of this substance.

Infliximab heals intestinal inflammatory lesions and restores growth in children with Crohn's disease

BACKGROUND

Infliximab has recently emerged as an efficacious agent for patients with severe Crohn's disease. There are only few studies on the use of infliximab in children with Crohn's disease: most of them are retrospective and deal only with the clinical response to the drug.

AIM

We aimed at assessing the efficacy of infliximab in children and adolescents with severe Crohn's disease recruited consecutively and followed up prospectively at a single centre. Clinical response, intestinal inflammation and growth pattern were evaluated.

PATIENTS

Eighteen patients entered into the trial (median age: 13 years, range: 6-18). They were referred because of severe symptoms with unsatisfactory response to conventional drugs.

METHODS

All patients received a baseline schedule of three intravenous infusions of infliximab (0, 2 and 6 weeks), 5 mg/kg. Paediatric Crohn's Disease Activity Index, nutritional and activity serum variables, and ileocolonoscopy (with histology) were evaluated before and 8 weeks after beginning the therapy. All patients had long-term administration of azathioprine (2 mg/kg per day). After the baseline schedule, eight patients had a retreatment infusion of infliximab (5 mg/kg) every 8 weeks. Weight and height Z scores were measured before starting the baseline infusion programme and after 6 months.

RESULTS

After 8 weeks of therapy, there was a dramatic improvement in Paediatric Crohn's Disease Activity Index, in nutritional and activity blood parameters, as well as in endoscopic and histological scores; 10 patients had a clinical remission (Paediatric Crohn's Disease Activity Index < or = 10), 12 patients had an inflammatory remission (decrease in both endoscopic and histological scores for > or = 50% as compared to baseline values). In all patients corticosteroids were stopped within 4 weeks after beginning infliximab therapy. After 6 months of therapy, Paediatric Crohn's Disease Activity Index was markedly lower than the pre-treatment value; however, it was significantly lower in patients on retreatment than in those who received only three infusions of infliximab. Furthermore, a significant increase in both weight and height Z scores was observed 6 months after beginning of the baseline infusion programme. Moreover, weight and height gain was significantly higher in patients on retreatment rather than in those treated only with three baseline infusions of infliximab. Mild infusion reactions controlled by slowing infusion rate were observed in four patients. No delayed hypersensitivity-like reactions were seen.

CONCLUSIONS

In children with severe Crohn's disease, infliximab is a safe and valuable treatment in inducing remission, in healing inflammatory lesions of the gut, as documented by endoscopy and histology, and in promoting growth. Retreatment infusions of infliximab may be suggested in childhood-onset Crohn's disease to maintain remission and reverse growth failure.

Idiopathic dilated cardiomyopathy associated with coeliac disease: the effect of a gluten-free diet on cardiac performance

An increased incidence of coeliac disease has recently been reported in patients with idiopathic dilated cardiomyopathy. This report deals with three patients with idiopathic dilated cardiomyopathy and coeliac disease who underwent clinical and laboratory evaluation to establish the effect of a gluten-free diet on cardiac performance. Two patients observed the gluten-free diet regimen very strictly, and, after a 28-month follow-up period, showed an improvement in echocardiographic parameters as well as in cardiological features and quality of life, as evaluated by the Minnesota Living with Heart Failure questionnaire and the Gastrointestinal Symptom Rating Scale questionnaire. The third patient did not observe the gluten-free diet and presented a worsening in the echocardiographic parameters and cardiological symptoms which required supplementary drug therapy. These preliminary data appear to suggest that the gluten-free diet may have a beneficial effect on cardiac performance in patients with idiopathic dilated cardiomyopathy.

Subcellular localization of oxidosqualene cyclases from Arabidopsis thaliana, Trypanosoma cruzi, and Pneumocystis carinii expressed in yeast

Cycloartenol synthase from Arabidopsis thaliana and lanosterol synthase from Trypanosoma cruzi and Pneumocystis carinii were expressed in yeast, and their subcellular distribution in the expressing cells was compared. Determination of enzymatic (oxidosqualene cyclase, OSC) activity and SDS-PAGE analysis of subcellular fractions proved that enzymes from T. cruzi and A. thaliana have high affinity for lipid particles, a subcellular compartment rich in triacylglycerols, and steryl esters, harboring several enzymes of lipid metabolism. In lipid particles of strains expressing the P. carinii enzyme, neither OSC activity nor the electrophoretic band at the appropriate M.W. were detected. Microsomes from the three expressing strains retained some OSC activity. Affinity of enzymes from A. thaliana and T. cruzi for lipid particles is similar to that of OSC of Saccharomyces cerevisiae, which is mainly located in this compartment. A different distribution of OSC in yeast cells suggests that they differ in some structural features critical for the interaction with the surface of lipid particles. Computer analysis supports the hypothesis of the structural difference since OSC from S. cerevisiae, A. thaliana, and T. cruzi lack or contain only one transmembrane spanning domain (a structural feature that makes a protein poorly inclined to associate with lipid particles), whereas OSC from P. carinii possesses six transmembrane domains. In the strain expressing cycloartenol synthase from A. thaliana, the accumulation of lipid particles largely exceeded that of the other strains.

Vinyl sulfide derivatives of truncated oxidosqualene as selective inhibitors of oxidosqualene and squalene-hopene cyclases

Various vinyl sulfide and ketene dithioacetal derivatives of truncated 2,3-oxidosqualene were developed. These compounds, having the reactive functions at positions C-2, C-15 and C-19 of the squalene skeleton, were studied as inhibitors of pig liver and Saccharomyces cerevisiae oxidosqualene cyclases (OSC) (EC 5.4.99.7) and of Alicyclobacillus acidocaldarius squalene hopene cyclase (SHC) (EC 5.4.99.-). They contain one or two sulfur atoms in alpha-skeletal position to carbons considered to be cationic during enzymatic cyclization of the substrate and should strongly interact with enzyme nucleophiles of the active site. Most of the new compounds are inhibitors of the OSC and of SHC, with various degrees of selectivity. The methylthiovinyl derivative, having the reactive group at position 19, was the most potent and selective inhibitor of the series toward S. cerevisiae OSC, with a concentration inhibiting 500% of the activity of 50 nM, while toward the animal enzyme it was 20 times less potent. These results could offer new insight for the design of antifungal drugs.

Value of antigliadin antibodies (AGA) in latent coeliac disease (CD)

BACKGROUND

The term latent coeliac disease (CD) is applied to patients who were previously shown to have a normal jejunal mucosa on a free diet. The aim of this study was to determine whether a high AGA value in the serum of patients with coeliac symptoms can also be regarded by itself, without typical mucosal atrophy, as a marker of latent CD, as some authors suggest in relatives of celiac patients.

METHODS

We observed 31 patients with suspected CD and pathological values of serum IgA ang IgG AGA. In all we performed intestinal biopsy, assayed antiendomisium antibodies (AEA) in serum, AGA IgA, IgG, and IgM in duodenal jejunal fluid and in some of the lymphocytcs CD3+ gamma/delta+ in the lamina propria of the intestinal mucosa.

RESULTS

In this study only pathological values of serum AGA without mucosa atrophy don't seem to be markers of latent CD, but an aspecific allergic response.

CONCLUSIONS

As shown by other authors serum AEA, intestinal fluid AGA IgM and lamina propria lymphocytes CD3+ gamma/delta+ seem markers of latent CD.

Chemokine concentrations in nasal washings of infants with rhinovirus illnesses

We determined RANTES (regulated on activation, normal T cell expressed and secreted) and interleukin-8 (IL-8) concentrations, and total white blood cell (WBC) and differential counts in nasal wash samples from rhinovirus-infected infants presenting with wheezing or acute upper respiratory illness alone and compared them with those from healthy infants. RANTES concentrations were significantly greater in acute samples from wheezy patients than in those from patients with acute upper respiratory illness only, or in control samples. IL-8 concentrations and WBC and neutrophil counts were significantly greater in acute samples from wheezy infants and patients with upper respiratory illness alone than in control samples, but they did not differ significantly between the 2 patient groups.

Rationally designed inhibitors as tools for comparing the mechanism of squalene-hopene cyclase with oxidosqualene cyclase

The inhibition of squalene-hopene cyclase (SHC) (E.C. 5.4.99.-), an enzyme of bacterial membranes catalyzing the formation of pentacyclic sterol-like triterpenes, was studied by using different classes of compounds originally developed as inhibitors of oxidosqualene cyclase (OSC) (E.C. 5.4.99.7), the enzyme of eukaryotes responsible for the formation of tetracyclic precursors of sterols. The mechanism of cyclization of squalene by SHC, beginning with a protonation of the 2,3 double bond by an acidic residue of the enzyme, followed by a series of electrophilic additions of the carbocationic intermediates to the double bonds, is similar to the mechanism of cyclization of 2,3-oxidosqualene by OSC. The inhibitors studied included: (i) analogs of the carbocationic intermediates formed during cyclization, such as aza-analogs of squalene and 2,3-oxidosqualene; (ii) affinity-labeling inhibitors bearing a methylidene reactive group; and (iii) vinyldioxidosqualenes and vinylsulfide derivatives of the substrates. Comparison of the results obtained with the two enzymes, SHC and OSC, showed that many of the most effective inhibitors of OSC were also able to inhibit SHC, while some derivatives acted as specific inhibitors. Differences could be easily explained on the basis of the different substrate specificity of the two enzymes.

Stereospecific syntheses of trans-vinyldioxidosqualene and 3-hydroxysulfide derivatives, as potent and time-dependent 2,3-oxidosqualene cyclase inhibitors

trans-Vinyldioxidosqualene and beta-hydroxysulfide derivatives were synthesized stereospecifically and evaluated as inhibitors of animal and yeast oxidosqualene cyclases. Only trans-vinyldioxidosqualene and 2,3-epoxy-vinyl-beta-hydroxysulfides, having the reactive function at crucial positions 14,15 and 18,19, were active as inhibitors of animal and yeast cyclases. (14-trans)-28-Methylidene-2,3: 14,15-dioxidoundecanorsqualene 27 was the most potent inhibitor of the series of pig liver cyclase, with an IC50 of 0.4 microM, and it behaved also as the most active time-dependent inhibitor of the animal enzyme.

[Reappearance of alopecia areata in a coeliac patient during an unintentional challenge with gluten]

A patient with coeliac disease presenting alopecia areas as the only symptom is described. Alopecia disappeared completely after a few months of strict gluten free diet and reappeared after an unintentional prolonged introduction of gluten. After a severe gluten free diet, a new and persistent hair growth in the alopecia areas was observed. The possibility a direct relationship in some cases, between coeliac disease and alopecia areata is confirmed.

Prevalence of coeliac disease in idiopathic dilated cardiomyopathy

We examined 52 patients with idiopathic cardiomyopathy (IDCM) for coeliac disease. Three of them had coeliac disease, suggesting that prevalence of coeliac disease in IDCM patients is increased.

19-Azasqualene-2,3-epoxide and its N-oxide: metabolic fate and inhibitory effect on sterol biosynthesis in Saccharomyces cerevisiae

19-Azasqualene-2,3-epoxide was more inhibitory than the corresponding N-oxide against 2,3-oxidosqualene cyclase (OSC) solubilized from Saccharomyces cerevisiae (IC50 7+/-2 and 25+/-5 microM, respectively). Both compounds showed a reversible, noncompetitive-type inhibition on solubilized OSC. Different inhibitory properties between the compounds were especially evident when measuring [14C]acetate incorporation into nonsaponifiable lipids extracted from treated cells. In cells treated with 19-azasqualene-2,3-epoxide at 30 microM, the radioactivity associated with the oxidosqualene fraction, which was negligible in the controls, rose to over 40% of the nonsaponifiable lipids, whereas it remained at a slightly appreciable level in cells treated with the N-oxide derivative under the same conditions. 19-Azasqualene-2,3-epoxide was also more effective than the N-oxide as a cell growth inhibitor (minimal concentration of compound needed to inhibit yeast growth: 45 and >100 microM, respectively). The two inhibitors underwent different metabolic fates in the yeast: while 19-azasqualene-2,3-epoxide did not undergo any transformation, its N-oxide was actively reduced to the corresponding amine in whole and in "ultrasonically stimulated" cells. The N-oxide reductases responsible for this transformation appear to be largely confined within the microsomal fractions and require NADPH for their activity. A possible relationship between the inhibitory properties of the two compounds and their metabolic fates is discussed.

HCV core immunodominant region analysis using mouse monoclonal antibodies and human sera: characterization of major epitopes useful for antigen detection

Monoclonal antibodies (MAbs) were generated by immunizing mice with a truncated recombinant protein corresponding to the immunodominant region (residues 1-120) of hepatitis C virus (HCV) nucleocapsid protein. The specific recognition by either human sera or mouse monoclonal antibodies of overlapping peptides spanning the core region 1-120 as well as the comparison with epitopes described earlier allowed the fine mapping of HCV core. Within the region 1-120, the major antigenic domain could be restricted to the first 45 amino acids. Indeed, the peptide S42G (residues 2-45) allowed the detection of an anti-HCV core response by all anticore-positive human sera examined. According to their epitope localization, three groups of mouse MABs could be evidenced that were directed against different regions of core. Group II MAbs recognized a strictly linear epitope (QDVKF, residues 20-24), whereas group I MABs were directed against a conformational epitope mainly located at the amino acid residues (QIVGG, 29-33). The epitope of group III MABs was also conformational (PRGRRQPI, residues 58-65). These three epitopes appeared close but different from the three major human epitopes RKTKRNTN, VYLLPR, and GRTWAQPGYPWPLY (residues 7-17, 34-39, and 73-86, respectively). Group II MAB 7G12A8 and group I MAB 19D9D6 were used in a sandwich ELISA for the capture and the detection, respectively, of viral core antigen in sera of patients with chronic HCV infection. After treatment of sera with triton x 100 in acidic conditions, amounts of viral antigen as low as 20 pg/ml of sera could be detected.

Association between insulin dependent diabetes mellitus and coeliac disease. A study on 175 diabetes patients

BACKGROUND

The association between diabetes mellitus and coeliac disease has been known for many years. In a random group of 175 insulin dependent diabetes mellitus patients of varying ages the following tests have been carried out: serum antigliadin antibodies (AGA) of IgA and IgG class, antireticulin antibodies (ARA) and antiendomisyum antibodies (AEA), both of IgA class.

MATERIALS AND METHODS

The patients, 85 males and 90 females, had ages ranging from 1 yr to 30 yrs (102 in paediatric age--mainly between 6 and 14 years--and 73 adults). Patients with pathological values for AEA and/or ARA underwent an intestinal biopsy.

RESULTS

Out of 175 patients studied, 21 had pathological values for AEA with or without pathological values for ARA and AGA, and 2 patients had only pathological values for ARA. 23 patients (21 with pathological values for AEA with or without ARA and AGA, 2 only for ARA ) underwent intestinal biopsy, all patients with pathological values for AEA had villous atrophy. The prevalence of coeliac disease among IDDM patients was 8.8% (95% CI 3.3 to 14.3) for the children and 16.4% (95% CI 7.9 to 24.9) for the adults. In patients with mucous atrophy, ARA, AGA IgA and IgG were pathological in 85%, 71% and 61% respectively. Symptoms and insulin requirements in all patients affected by coeliac disease before and after one year on a gluten free diet were also evaluated. The patients had clinical features with prevalently one or only few atypical symptoms which disappeared on a gluten free diet. Insulin requirements after one year on a gluten free diet appeared unchanged in coeliac patients.

CONCLUSIONS

The need to screen all diabetic patients for coeliac disease is underlined.

29-Methylidene-2,3-oxidosqualene derivatives as stereospecific mechanism-based inhibitors of liver and yeast oxidosqualene cyclase

Two pairs of isomers (18Z)- (8), (18E)-29-methylidene-2,3-oxidohexanorsqualene (21), and (18Z)- (31), (18E)-29-methylidene-2,3-oxidosqualene (34), have been obtained in a fully stereospecific manner, as inhibitors of rat and yeast oxidosqualene cyclase. A new method for the synthesis of C22 squalene aldehyde 2,3-epoxide is reported, as well as that of other 19-modified 2,3-oxidosqualene analogues. We found that the activity is the opposite in the two series: the (E)-hexanormethylidene 21 and the (Z)-methylidene 31 are potent and irreversible inhibitors of oxidosqualene cyclase, while (Z)-hexanormethylidene 8 and (E)-methylidene 34 are almost completely inactive. Reduction of the 18,19-double bond, such as in 39, eliminates the activity, while removal of both of the 19-linked groups such as in heptanor derivative 40 greatly reduces inhibition of the enzyme. (E)-Hexanormethylidene 21 results the first irreversible inhibitor of the series toward the yeast enzyme.

[High prevalence of hepatitis C virus infection in patients with non-Hodgkin's lymphoma at the onset. Preliminary results of an Italian multicenter study]

143 patients with non-Hodgkin lymphoma (NHL) at the onset entered this perspective study on NHL-associated risk factors. They were 87 males and 56 females with a mean age of 52.3 years (range 14.6-82.3). An associated hepatitis C virus (HCV) infection was found in 16 of the 143 NHL cases (11.2%; 95% CI 6.5-17.5). They were 11 males and 5 females [mean age 59.9] year with disseminated (13/16) or localized NHL disease (3/16)]. The NHL histological subgroup was low grade (6/16), intermediate grade (2/16) or high grade (8/16). The cell origin was B in 15/16 cases and B cell-T cell rich in 1/16. The discovery of HCV infection was contemporary to lymphoma diagnosis in 6/16 cases but preceded the NHL onset in the other 10 patients. In these 10 patients the median time between HCV infection diagnosis and NHL onset was 3.6 years (range 1-14.5). These data confirm that in Italy the prevalence of HCV infection in patients with NHL (11.2%) is significantly higher than expected in the general population (1.3-3.2%). The finding that, in most cases, HCV infection was definitely antecedent to NHL onset, usually by years, adds evidence to the possible causative role of the HCV in lymphomagenesis.

Impact of modification of diagnostic techniques and criteria on the presentation of celiac disease in the last 16 years. Observation in Rome

Age of diagnosis and clinical pattern were studied in 97 celiac patients, diagnosed with jejunal biopsy, between 1976-1991. They were selected on the basis of clinical and laboratory patterns. The laboratory tests utilized were steatorrhea and xylose in the first years, while in recent years AGA, ARA and AEA were also utilized. The patients were divided into two groups, based on the year of first biopsy. The first group includes 36 cases diagnosed between 1976-1985, the second one 61 cases diagnosed between 1986-1991. In recent years an increase in the number of cases has been observed in our centre, particularly in patients over 2 years of age, while the number of diagnoses in children under 2 years of age was essentially the same. So-called typical symptoms prevailed in the first group, while so-called atypical symptoms are more frequent in the second. If an increase of incidence of celiac disease within the population is confirmed, a mass screening will be necessary in order to identify the atypical forms, utilizing laboratory tests, for the purpose of selecting patients to be subjected to an intestinal biopsy.

1H-NMR relaxometric study of pancreatic serine (pro)enzyme inhibition by a Gd(III) chelate bearing boronic functionalities

Binding of the paramagnetic N,N"-bis(m-boroxyphenylcarbamoylmethyl)-diethylenetriamine-N,N', N"-triacetic acid Gd(III) [sequence: see text] complex (GdBB) to chymotrypsin, chymotrypsinogen, trypsin, trypsinogen and pancreatic elastase has been investigated by 1H-NMR relaxometry, between pH 6.0 and 8.5, at 25.0 degrees C. Values of Ki for the competitive inhibition of serine proteinases by GdBB are in excellent agreement with values of Kd obtained by 1H-NMR relaxometry, suggesting that the substrate and the paramagnetic complex bind to the same region. Moreover, 1H-NMR relaxometry allowed to determine values of Kd for GdBB binding to chymotrypsinogen and trypsinogen, both devoid of catalytic activity. The increase of the water proton relaxation rate upon GdBB binding to serine (pro)enzymes may be useful in the design of novel functional contrast agents for magnetic resonance imaging.

Azide, cyanide, fluoride, imidazole and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative: a comparative study

Azide, cyanide, fluoride, imidazole, and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative has been investigated, from the thermodynamic viewpoint, at pH 7.5 and 25.0 degrees C. Ligand affinity for ferric and ferrous carboxymethylated cytochrome c is higher by about 30- and 400-fold, respectively, than that observed for the native protein. The results here reported: (i) allow the estimation, for the first time, of the ligand-independent free energy associated with the heme-iron sixth coordination bond in ferric and ferrous native cytochrome c, which turns out to be +8.4 kJ mol-1 and +14.6 kJ mol-1, at 25.0 degrees C, respectively, and (ii) suggest an interplay between redox, structural, ligand binding, and recognition properties of cytochrome c.

The coeliac iceberg in Italy. A multicentre antigliadin antibodies screening for coeliac disease in school-age subjects

BACKGROUND

Recent studies suggest that coeliac disease (CD) is one of the commonest, life-long disorders in Italy. The aims of this multicentre work were: (a) to establish the prevalence of CD on a nationwide basis; and (b) to characterize the CD clinical spectrum in Italy.

PATIENTS AND METHODS

Fifteen centres screened 17,201 students aged 6-15 years (68.6% of the eligible population) by the combined determination of serum IgG- and IgA-antigliadin antibody (AGA) test; 1289 (7.5%) were IgG and/or IgA-AGA positive and were recalled for the second-level investigation; 111 of them met the criteria for the intestinal biopsy: IgA-AGA positivity and/or AEA positivity or IgG-AGA positivity plus serum IgA deficiency.

RESULTS

Intestinal biopsy was performed on 98 of the 111 subjects. CD was diagnosed in 82 subjects (75 biopsy proven, 7 not biopsied but with associated AGA and AEA positivity). Most of the screening-detected coeliac patients showed low-grade intensity illness often associated with decreased psychophysical well-being. There were two AEA negative cases with associated CD and IgA deficiency. The prevalence of undiagnosed CD was 4.77 x 1000 (95% CI 3.79-5.91), 1 in 210 subjects. The overall prevalence of CD, including known CD cases, was 5.44 x 1000 (95% CI 4.57-6.44), 1 in 184 subjects. The ratio of known to undiagnosed CD cases was 1 in 7.

CONCLUSIONS

These findings confirm that, in Italy, CD is one of the most common chronic disorders showing a wide and heterogeneous clinical spectrum. Most CD cases remain undiagnosed unless actively searched.

Inhibition of 2,3-oxidosqualene cyclase and sterol biosynthesis by 10- and 19-azasqualene derivatives

The inhibition of 2,3-oxidosqualene-lanosterol cyclase (EC 5.4.99.7) (OSC) by new azasqualene derivatives, mimicking the proC-8 and proC-20 carbocationic high-energy intermediates of the cyclization of 2,3-oxidosqualene to lanosterol, was studied using pig liver microsomes, partially purified preparations of OSC, and yeast microsomes. The azasqualene derivatives tested were: 6E- and 6Z-10aza-10,11-dihydrosqualene-2,3-epoxide 17 and 18, 19-aza-18,19,22,23-tetrahydrosqualene-2,3-epoxide 19 and its corresponding N-oxide 20, and 19-aza-18,19,22,23-tetrahydrosqualene 21. The compounds 17 and 19 (i.e. the derivatives bearing the 2,3-epoxide ring and the same geometrical configuration as the OSC substrate) were effective inhibitors, as shown by the Ki obtained using partially purified OSC: 2.67 microM and 2.14 microM, respectively. Compound 18, having an incorrect configuration and the 19-aza derivative 21, lacking the 2,3-epoxide ring, were poor inhibitors, with IC50 of 44 microM and 70 microM, respectively. Compound 21 was a competitive inhibitor of OSC, whereas 17 and 19 were noncompetitive inhibitors, and showed a biphasic time-dependent inactivation of OSC, their apparent binding constants being 250 microM and 213 microM, respectively. The inhibition of sterol biosynthesis was studied using human hepatoma HepG2 cells. The incorporation of [14C] acetate in the C27 sterols was reduced by 50% by 0.55 microM 17, 0.22 microM 19, and 0.45 microM 21, whereas 2 microM 18 did not affect sterol biosynthesis. In the presence of 17, 19 and 21, only the intermediate metabolites 2,3-oxidosqualene and 2,3,22,23-dioxidosqualene accumulated, demonstrating a very specific inhibition of OSC.

Inhibition of bovine beta-trypsin, human alpha-thrombin and porcine pancreatic beta-kallikrein-B by 4',6-diamidino-2-phenylindole, 6-amidinoindole and benzamidine: a comparative thermodynamic and X-ray structural study

The inhibitory effect of 4',6-diamidino-2-phenylindole (DAPI) and 6-amidinoindole on the catalytic properties of bovine beta-trypsin (trypsin), human alpha-thrombin (thrombin) and porcine pancreatic beta-kallikrein-B (kallikrein) was investigated (between pH 3.0 and 7.0, I = 0.1 M; T = 30.0 +/- 0.5 degrees C), and analyzed in parallel with that of benzamidine, commonly taken as a molecular inhibitor model of serine proteinases. Next, the X-ray crystal structure of the trypsin:DAPI complex was solved at 1.9 A resolution (R = 0.161). Over the whole pH range explored, values of the association inhibition constant (Ki) for DAPI and 6-amidinoindole binding to trypsin, thrombin and kallikrein are higher than those found for benzamidine association, suggesting a binding mode of DAPI to the enzyme primary specificity pocket-based on the indole moiety of the inhibitor. On lowering the pH from 5.5 to 3.0, the decrease in affinity for DAPI, 6-amidinoindole and benzamidine binding to trypsin, thrombin and kallikrein reflects the acidic pK shift of the Asp189 invariant residue, present at the bottom of the primary specificity subsite of the serine proteinases considered, from 4.5, in the free enzyme, to 3.7, in the proteinase:inhibitor complexes. Inspection of the refined crystal structure of the trypsin:DAPI complex, however, does not allow a unique interpretation of the inhibitor binding mode. The present data were analysed in parallel with those reported for related serine (pro)enzyme/inhibitor systems.

2,3-Oxidosqualene cyclase: from azasqualenes to new site-directed inhibitors

2,3-Oxidosqualene cyclases (OSC) are enzymes which convert 2,3-oxidosqualene (OS) into polycyclic triterpenoids such as lanosterol, cycloartenol, and alpha- and beta-amyrin. Our interest in the study of OSC is the development of new OSC inhibitors for potential use as hypocholesterolemic, antifungal, or phytotoxic drugs. In particular, we describe the biological activity and the mechanism of a series of acyclic azasqualene derivatives mimicking the C-2, C-8, and C-20 carbonium ions formed during OS cyclization. Some of these carbonium ion analogues are very promising as specific hypocholesterolemic agents. The toxicity, the biodistribution, and the pharmacokinetics of different azasqualene derivatives in mice are also presented. In order to obtain new, site-directed irreversible inhibitors of OSC, a series of squalene derivatives containing functional groups that can link covalently to an active-site thiol group was designed. Among these compounds, squalene maleimide was the most active toward mammalian OSC, whereas squalene Ellman behaved as an irreversible inhibitor of OSC from yeast.

Inhibition of sterol biosynthesis in Saccharomyces cerevisiae and Candida albicans by 22,23-epoxy-2-aza-2,3-dihydrosqualene and the corresponding N-oxide

The abilities of 22,23-epoxy-2-aza-2,3-dihydrosqualene and the corresponding N-oxide, 22,23-epoxy-2-aza-2,3-dihydrosqualene-N-oxide, to inhibit sterol biosynthesis were studied in microsomes and cells of Saccharomyces cerevisiae and Candida albicans. 22,23-Epoxy-2-aza-2,3-dihydrosqualene, which differs from the other inhibitor only in lacking oxygen at position 2, exhibited higher inhibitory properties in all preparations tested. The different levels of effectiveness of the two azasqualene derivatives were evident mostly in microsomes from S. cerevisiae (the 50 inhibitory concentrations of the 2-aza derivative and the corresponding N-oxide on oxidosqualene cyclase were 30 and 120 microM respectively) and in cell cultures of the same strain (1 order of magnitude separated the inhibitory activities of the two compounds on sterol biosynthesis). A possible explanation for the differences between 22,23-epoxy-2-aza-2,3-dihydrosqualene and the corresponding N-oxide arose from the study of their metabolic fates in vivo and in vitro. While the 2-aza derivative did not undergo any transformation, the N-oxide compound was actively reduced to the corresponding amine in microsomes and in cells of both yeast strains. 22,23-Epoxy-2-aza-2,3-dihydrosqualene-N-oxide seems to behave as a proinhibitor of sterol biosynthesis, becoming active only after transformation into the active form 22,23-epoxy-2-aza-2,3-dihydrosqualene.

3-Carboxy-4-nitrophenyl-dithio-1,1',2-trisnorsqualene: a site-directed inactivator of yeast oxidosqualene cyclase

The role and location of essential thiol groups in 2,3-oxidosqualene cyclase from Saccharomyces cerevisiae was examined (i) by comparing inactivation properties of two known thiol reagents, 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and 2-nitro-5-thiocyanobenzoic acid (NTCB), with 3-carboxy-4-nitrophenyl-dithio-1,1',2-trisnorsqualene (CNDT-squalene), a new thiol reagent designed as a site-directed inactivator of oxidosqualene cyclase and (ii) by testing the ability of the substrate to protect the enzyme against inactivation by the reagents. All reagents gave a time-dependent inactivation following pseudo-first order kinetics. DTNB and CNDT-squalene showed comparable inactivation ability (Ki = 0.67 and 1.21 mM), whereas NTCB was less effective (Ki = 15.6 mM). Strong differences between the two most active inhibitors, DTNB and CNDT-squalene, were observed when the enzyme was saturated with substrate prior to incubation with the thiol reagent. While substrate did not protect the enzyme against the inactivation caused by DTNB, a reduction in the inactivation ability of CNDT-squalene was observed under protection conditions. The data suggest that the squalene-like inactivator modifies a thiol group located at the active site of the enzyme.