Structural stability study of protein monolayers in air

The assessment of the folding and of the structural stability of a protein in air, upon immobilization in the solid state, represents a critical point from both a fundamental point of view and for the development of solid state nanobioelectronics. The recent demonstrations by Rinaldi et al. [R. Rinaldi et al., Adv. Mater. 14, 1453 (2002); Appl. Phys. Lett. 82, 472 (2003); Ann. (N.Y.) Acad. Sci. 1006, 187 (2003)] of protein-based solid state devices and transistors working in air have raised an intriguing question about the behavior of a biomolecule under nonphysiological conditions. The operation principle of the realized devices is based on the physiological electron transfer function of the metalloprotein azurin. This means that azurin should retain its shape and functionality also in the solid state when utilized in air and at room temperature. In this Brief Report, we prove this claim by analyzing the conformational state of the azurin monolayers developed for such devices by means of intrinsic fluorescence spectroscopy. We show that the immobilization of azurins in the solid state under nonliquid conditions, by means of a specific chemisorption process, does not necessarily lead to protein denaturation. This result is of great importance because it opens up interesting perspectives for the development of solid state hybrid nanodevices for electronic applications requiring nonliquid environments.

Ambipolar transistors based on azurin proteins

A new type of transistor is presented. It is realised by using a metalloprotein; namely, azurin. Thanks to their natural functional characteristics, which involve inter- and intramolecular electron transfer, metalloproteins are good candidates for biomolecular nanoelectronics. The implementation of a prototype of protein transistor operating in air and in the solid state based on self-organised films of azurins is reported. Experimental current-voltage characteristics are shown. The new device presents an ambipolar behaviour as the gate bias voltage is changed. Exploiting this peculiar characteristic, a fully integrated logic gate which can be a good starting point for a new class of nanoelectronics devices has been realised.

Deep neck infection: a present-day complication. A retrospective review of 83 cases (1998-2001)

Deep neck infections are less and less frequent today than in the past. Nevertheless, their complications are often life-threatening. The present study reviews the experience of the Department of Otolaryngology and Head and Neck Surgery of Padua with deep neck infections during the period from 1998 to 2001. Eighty-three patients (55 males and 28 females) were retrospectively considered. The site of origin of deep neck infection was identified in 76 patients (91%). The most common cause was dental infection, occurring in 35 cases (42%). In 12 cases (14%) deep neck infection was a complication of oropharyngeal infection. The relatively high incidence of Peptostreptococcus sp, Streptococcus viridans, Streptococcus intermedius and constellatus isolation was consistent with the high rate of odontogenic cases. Surgery was advocated as the treatment for any infection of the deep neck spaces. The recent series has demonstrated that medical treatment did not seem to increase complication rates or mortality. Our tailored approach (medical or medical and surgical) based on clinical and radiological evidence was successful in 97% of the patients.

Clinical management and molecular cytogenetic characterization in a 45,X/46,X,idic(Yp) patient with severe hypospadia

Cryptorchidism and proximal hypospadia in a newborn are highly suspicious for an intersex disorder, and proper investigations should be planned immediately after birth. In some hypospadic patients, the presence of a palpable gonad in the scrotum may induce to assign the male sex, whereas the anatomy of internal and external genitalia could be extremely complex, requiring an accurate evaluation before any definitive attribution of gender. The authors present a case of an infant, referred to the hospital for surgical treatment of a proximal hypospadia, who showed ambiguous external genitalia, absence of the right gonad, a partially dysgenetic left testis, and presence of both müllerian and wolffian structures. Cytogenetic analysis detected a mosaicism with a cell line showing an isodicentric Yp chromosome and a second one, a 45, X chromosomal complement. Because the baby had been assigned previously to male gender, he underwent a staged masculinizing correction of the genital anomalies. The authors discuss the necessity of a careful evaluation of these patients at birth by a multispecialistic team, for appropriate sex assignment and for the assessment of the risk of neoplastic degeneration.

Intrinsic fluorescence spectroscopy of glutamate dehydrogenase: Integrated behavior and deconvolution analysis

In this paper, we present a deconvolution method aimed at spectrally resolving the broad fluorescence spectra of proteins, namely, of the enzyme bovine liver glutamate dehydrogenase (GDH). The analytical procedure is based on the deconvolution of the emission spectra into three distinct Gaussian fluorescing bands G(j). The relative changes of the G(j) parameters are directly related to the conformational changes of the enzyme, and provide interesting information about the fluorescence dynamics of the individual emitting contributions. Our deconvolution method results in an excellent fitting of all the spectra obtained with GDH in a number of experimental conditions (various conformational states of the protein) and describes very well the dynamics of a variety of phenomena, such as the dependence of hexamers association on protein concentration, the dynamics of thermal denaturation, and the interaction process between the enzyme and external quenchers. The investigation was carried out by means of different optical experiments, i.e., native enzyme fluorescence, thermal-induced unfolding, and fluorescence quenching studies, utilizing both the analysis of the "average" behavior of the enzyme and the proposed deconvolution approach.

Accuracy of ICD-9 codes in identifying ischemic stroke in the General Hospital of Lugo di Romagna (Italy)

We assessed the sensitivity and the positive predictive value (PPV) of the ICD-9 codes in identifying ischemic strokes. The study involved the cross-sectional comparison between patients with an ischemic stroke diagnosis made by neurologists and patients with the 434 or 436 discharge codes. Sensitivity of the codes (all diagnostic levels and first level respectively) was 82% and 76%; PPV: 71% and 76%. The annual crude incidence of ischemic stroke was 2.62 per 1000 based on verified strokes and 3.03 per 1000 based on 434 or 436 coded medical records (at all diagnostic levels). Thirty-day case fatality ratio was 22.3% in verified strokes and 36.8% among patients diagnosed with codes 434 or 436 but without stroke (all levels). Our results disclosed inaccuracy in use of the ICD-9 codes in the diagnosis of ischemic stroke in the general hospital of Lugo di Romagna, Ravenna Province, Italy. The misdiagnosis of patients could be influenced by the degree of severity of clinical features. Epidemiological data and cost-analysis forecasts based only on the ICD-9 system must be considered with caution.

Cytogenetic and molecular characterization of a de novo 4q24qter duplication and correlation to the associated phenotype

We report on a newborn with severe psychomotor retardation, minor anomalies, congenital heart defects, thumb and urogenital abnormalities. Cytogenetic analysis showed a 4q24qter duplication, never described before, as the result of a de novo t(4;14). The extension of the duplicated 4q region was defined by FISH using YAC probes. The breakpoint was localized between 106.3cM (YAC 800f2, D4S1572) and 111 cM (YAC 744e4, D4S1564). Comparing our patient with those previously reported in literature, we observed some features mature frequently reported in these patients: psychomotor retardation, retromicrognathia, low set and/or malformed ears and some more specific traits: congenital cardiac defects, hypoplastic thumb and urogenital abnormalities.

Optical characterization of glutamate dehydrogenase monolayers chemisorbed on SiO2

This paper describes the formation of glutamate dehydrogenase monolayers on silicon dioxide, and their characterization by means of physical techniques, i.e., fluorescence spectroscopy and Fourier-transform infrared spectroscopy. Detailed investigations of the intrinsic stability of native proteins in solution were carried out to elucidate the occurrence of conformational changes induced by the immobilization procedure. The enzyme monolayers were deposited on SiO2 after preexposing silicon surfaces to 3-aminopropyltriethoxysilane and reacting the silylated surfaces with glutaric dialdehyde. The optical characterization demonstrates that the immobilization does not interfere with the fold pattern of the native enzyme. In addition, fluorescence spectroscopy, thermal denaturation, and quenching studies performed on the enzyme in solution well describe the folding and unfolding properties of glutamate dehydrogenase. The photophysical studies reported here are relevant for nanobioelectronics applications requiring protein immobilization on a chip.

Chronic viral hepatitis: a prospective factor against atherosclerosis. A study with echo-color Doppler of the carotid and femoral arteries and the abdominal aorta

OBJECTIVE

To evaluate if chronic viral hepatitis may be a protective factor for atherosclerosis.

METHODS

Echo-doppler of the carotid and femoral arteries and the abdominal aorta was used to examine 48 patients with a histological diagnosis of chronic viral hepatitis (42 hepatitis C virus-related, 6 hepatitis B virus-related), with a low degree of activity and preserved hepatic function, and 50 controls matched for age, sex and exposure to the main risk factors of atherosclerosis.

RESULTS

The prevalence of atherosclerosis in patients was clearly lower than in controls in all investigated sites, although the difference was statistically significant only for the carotid arteries. The percentage of patients with carotid atherosclerosis was 27% in patients with liver disease and 56% in controls (P<0.005). Furthermore, and again at the carotid level, the patients with liver disease had fewer atheromatous lesions (16 plaques vs. 59; P<0.001) than controls as well as a lower degree of vessel stenosis. None of the liver disease patients presented with vessel stenosis above 30% vs. 8% of control subjects.

CONCLUSIONS

Chronic viral hepatitis may help prevent from atherosclerosis.

Validation of symptoms related to excessive daytime sleepiness

The aim of this study was to validate some recurring definitions of excessive daytime sleepiness (EDS) obtained from descriptive epidemiological studies. We devised questions concerning concepts such as "tiredness", "resistible sleepiness", "irresistible sleepiness" and "sudden sleep attacks". The validation was done by comparing the answers with the results of the Multiple Sleep Latency Test (MSLT), considered the gold standard, or criterion measure, for the diagnosis of EDS. The sample study comprised 73 subjects, 57 outpatients referred to our Sleep Center complaining of daytime sleepiness, snoring or sleep apnea and 16 inpatients admitted to our Neurological Institute for causes other than sleep disorders. A moderate correlation (p = -0.38, 95% confidence interval -0.57 to -0.19) was found between "irresistible sleepiness" and mean sleep latency (MSL). The best combinations of sensitivity and specificity in identifying EDS, for 5- and 8-min MSL cutoffs, were observed for the questions concerning "sudden sleep attacks" and "irresistible sleepiness" (areas under the receiver-operating characteristic curves = 66 and 67%, respectively). The subitems exploring the frequency and situations of occurrence of these symptoms improved the validity in identifying EDS. The items regarding "tiredness" and "resistible sleepiness" were not related to the results of the MSLT. In subgroup analysis, irresistible sleepiness failed to identify pathologic MSLT in sleep-disordered breathing subjects. According to previous observations, we suggest that the concept of sleepiness includes various domains heterogeneously related with MSL and that questionnaires must be tailored to the different populations studied.

[Circadian variations in the onset of acute myocardial infarction]

BACKGROUND

Several studies have observed a circadian pattern in the onset of acute myocardial infarction (AMI), with a peak incidence in the morning hours. It has been suggested that different circadian rhythms may exist in various subgroups of patients.

METHODS

This study sought to determine whether the circadian incidence of AMI varied by sex, age, cardiovascular risk factors, previous history of ischemic accidents, the site of AMI, and the short-term outcome. These possibilities were examined in a population of 597 consecutive patients with AMI, admitted to the coronary care unit. 548 patients have been included in the study, 442 men (80.6%) and 106 women (19.4 %); mean age 64.5 years.

RESULTS

A peak incidence of AMI was found between 06.01 a.m. and 12.00 a.m. (32.4%; p<0.0002). This peak was present in patients 65 years old (33.2%; p<0.005), in men (32.5%; p<0.0002) but not in women, in smokers (32.1%; p<0.0005) and in those that did not smoke (33.0%; p<0.04), in patients with hypercholesterolemia (34.9%; p<0.006 ) and without hypercholesterolemia (31.1%; p<0.03). A circadian rhythm was absent in diabetics, hypertensives and in patients with a history of previous cardiovascular events. Regarding the site of AMI, inferior AMI showed an increased incidence between 06.01 a.m. and 12.00 a.m. (36.2%; p<0.002), while the circadian distribution of anterior AMI, as well as non-Q wave AMI, did not show this incidence. Finally, higher mortality was reported in patients with an AMI onset at night (22.3%).

CONCLUSIONS

These results give further clues in understanding the external and inner factors acting in the morning hours as triggers for AMI.

CDKN2A novel mutation in a patient from a melanoma-prone family

CDKN2A is thought to be the main candidate gene for melanoma susceptibility. Deletion or mutations in the CDKN2A gene may produce an imbalance between functional p16 and cyclin D, causing abnormal cell growth. We here describe a novel mutation consisting of a 1 bp deletion at nucleotide position 201 (codon 67) (CACGGcGCG) resulting in a truncated protein (stop codon 145). The patient, a female subject from a melanoma-prone family, presented at the age of 47 years with a superficial spreading melanoma of the trunk. Her father had colon cancer at the age of 43 years and melanoma at 63 years, her uncle suffered from gastric cancer, and her grandfather had laryngeal cancer.

Idiopathic chronic constipation: tachykinins as cotransmitters in colonic contraction

BACKGROUND

Tachykinins (TKs) have been shown to be involved in the excitatory enteric motor pathway. This study aimed to examine the direct and nerve-mediated effect of specific NK1, NK2 and NK3 receptor agonists and antagonists in colonic preparations from control subjects and patients with idiopathic chronic constipation (ICC).

MATERIALS AND METHODS

Cumulative concentrations of Sar9Met(O2)11 substance P (selective NK1 receptor agonist), [Ala5,beta-Ala8]-neurokinin A (4-10) (selective NK2 receptor agonist) and [MePhe7]-neurokinin B (selective NK3 receptor agonist) were tested on colonic circular muscle strips to evaluate the direct drug effects. In addition, in the presence of atropine, the role of TKs in the off-contraction that follows the typical inhibitory response evoked by low frequencies of electrical field stimulation (0.5--10 Hz, 20 V, 1 ms pulse trains lasting 1 min) was investigated.

RESULTS

In control preparations, the rank order of potency was: NK2 receptor-selective agonist > NK3 receptor-selective agonist > NK1 receptor-selective agonist. The off-contraction was found to be reduced by about 30--40% in colonic circular muscle from ICC patients with respect to controls. Incubation with the NK1 receptor agonist did not modify the off-contraction measurements in either control or ICC preparations. Conversely, both NK2 and NK3 receptor agonists significantly (P < 0.01) increased the off-contraction in ICC preparations only. This increased response was fully antagonized by MEN-10627, a NK2 and NK3 receptor antagonist depending on the dose.

CONCLUSIONS

We may conclude that ICC is hyporesponsive to TKs and that the contractile reflex to distension is greatly reduced in ICC disease, but can be restored by incubation with NK2 and NK3 receptor agonists.

Biophenotypes and survival of BRCA1 and TP53 deleted breast cancer in young women

The aim of this study was to examine the loss of heterozygosity (LOH) of BRCA1 (17q21) and TP53 (17p13.1) in early-onset breast cancer patients; to correlate biopathological characteristics with molecular alterations; and to investigate the survival of LOH-related cancers. BRCA1 and TP53 LOH were evaluated in 78 early-onset breast cancers (< or = 40 years, Group 1) and 80 patients with age > 55 years (Group 2). Cases were characterized for multiple biological markers (ER, PR, proliferation index (PI), NEU and p53). LOH was carried out on microdissected paraffin embedded tissues; microsatellites D17S855 (BRCA1) and D17S786 (TP53) were amplified by fluorescent PCR and analyzed by an automated DNA sequencer. Early-onset breast cancers showed a higher frequency of ductal histotype (89.7% vs. 56.3% p < 0.001), node-positive (53.8% vs. 38.7%), larger size (p = 0.017), higher mitotic rate (p = 0.025), higher nuclear and final grade (p = 0.01 and p = 0.001, respectively). D17S855 LOH was 32.8% in group 1 vs. 21% in group 2; D17S786 LOH was 50.7% vs. 31.3% (p = 0.03), respectively. BRCA1 LOH was correlated with higher PI (p = 0.032) and higher p53 expression (p < 0.001) in group 1 and with higher NEU expression (p = 0.028) in group 2. TP53 LOH was correlated with p53 overexpression (p = 0.03) in group 1. A worse clinical outcome in early-onset LOH related cancers emerged from follow-up data: TP53 and BRCA1 LOH were associated with a shorter relapse free interval (RFI) (p = 0.03) and a poorer overall survival (OS) (p = 0.04), respectively. This study underlines different biological profiles in the two age groups investigated, probably reflecting different mechanisms of carcinogenesis. In accordance with adverse histopathological features in early-onset patients, LOH-related cancers have an unfavorable prognosis.

Reactivity of cysteine-49 and its influence on the activation of microsomal glutathione transferase 1: evidence for subunit interaction

Microsomal glutathione transferase 1 is a homotrimeric detoxication enzyme protecting against electrophiles. The enzyme can also react with electrophiles, and when modification occurs at a unique Cys49 the reaction often results in activation. Here we describe the characterization of the chemical properties of this sulfhydryl (kinetic pK(a) was 8.8 +/- 0.3 and 9.0 +/- 0.1 with two different reagents) and we conclude that the protein environment does not lower the pK(a). Upon a direct comparison of the reactivity of Cys49 and low molecular weight thiols [L-Cys and glutathione (GSH)], the protein sulfhydryl displayed a 10-fold lower reactivity. The reactivity was correlated to reagent concentration in a linear fashion with a polar reagent, whereas the reactivity toward a hydrophobic reagent displayed saturation behavior (at low concentrations). This finding indicates that Cys49 is situated in a hydrophobic binding pocket. In a series of related quinones, activation occurs with the more reactive and less sterically hindered compounds. Thus, activation can be used to detect reactive intermediates during the metabolism of foreign compounds but certain intermediates can (and will) escape undetected. The reactivities of the three cysteines in the homotrimer were shown not to differ dramatically as the reaction of the protein with 4, 4'-dithiodipyridine could be fitted to a single exponential. On the basis of this result, a probabilistic expression could be used to relate the overall degree of modification to fractional activation. When N-ethylmaleimide activation (determined by the 1-chloro-2, 4-dinitrobenzene assay) was plotted against modification (determined with 4,4'-dithiodipyridine), a nonlinear relation was obtained, clearly showing that subunits do not function independently. The contribution to activation by single-, double-, and triple-modified trimers, were 0 +/- 0.06, 0.74 +/- 0.09, and 0.97 +/- 0.06, respectively. The double-modified enzyme appears partly activated, but this conclusion is more uncertain due to the possibility of independent modification of the purified enzyme upon storage. It is, however, clear that the single-modified enzyme is not activated whereas the triple-modified enzyme is fully activated. These observations together with the fact that MGST1 homotrimers bind only one substrate molecule (GSH) strongly support the view that subunits must interact in a functional manner.

[Autonomic neuropathy in a diabetic population. Validity of cardiovascular tests and correlations with the complications]

The disfunction of the autonomic system nervous is a frequent finding in diabetes mellitus. Among objective tests proposed for its diagnosis, those assessing cardiovascular reflexes (cardiovascular tests: CVTs) explore the autonomic functionality by means of a group of standardized manoeuvres of relatively easy execution that study the baroreceptorial reflex arc. In our study, CVTs were performed in a population of 207 diabetic patients with no symptoms of autonomic neuropathy. A computerized automatic system (Cardionomic) was utilized. CTVs included: Deep Breathing, Lying to Standing, Valsalva Manoeuvre, Orthostatic Hypotension, Standing to Lying and Cough Test. Diabetic patients were broken down in groups according to: a) age, b) HbA1c levels, c) disease duration. We have then compared the presence of diabetic complications between the group of diabetics positive for cardiovascular disautonomia (CVD+) with another group of diabetics who were negative for cardiovascular disautonomia (DCV-). Our results show a remarkable correlation between autonomic neuropathy and patients age, HbA1c levels and disease duration. Also they show a strong positive correlation between CDV+ and the severity of arteriopathy. We conclude that autonomic neuropathy may play an important role in the pathogenesis of diabetic arteriopathy.

Dot-and-fleck retinopathy in Alport syndrome caused by a novel mutation in the COL4A5 gene

PURPOSE

To describe an unusual form of dot-and-fleck retinopathy in a slower progressive form of X-linked Alport syndrome, caused by a novel missense mutation in the COL4A5 gene.

METHOD

Ophthalmic examination, polymerase chain reaction, and single-strand conformational polymorphism analysis of genomic DNA were performed in the proband.

RESULTS

Ophthalmoscopy revealed classic dot-and-fleck retinopathy but located in an unusual site. A novel COL4A5 gene mutation changing glycine to cysteine at 177 was identified.

CONCLUSIONS

Although there is no correlation between mutation site and the resulting phenotype in Alport syndrome, our findings suggest that further novel mutations and different ocular manifestations may be associated with Alport syndrome.

Endothelin-1-receptor-mediated responses in resistance vessels of young and adult spontaneously hypertensive rats

OBJECTIVE

To assess whether primary changes in endothelin-1 (ET-1) receptor responsiveness or secondary vessel functional modifications could characterize the effects evoked by ET-1 in the mesenteric vascular bed (MVB) of prehypertensive 5-week-old and 12-week-old spontaneously hypertensive rats (SHRs).

DESIGN AND METHODS

We used male 5-week-old and 12-week-old SHRs and sex- and age-matched Wistar-Kyoto (WKY) rats as controls. ET-1 receptor responsiveness was evaluated by ET-1 (0.04-2 micromol/l) concentration-response curves and repeated with indomethacin and BQ-123 (0.1-0.5 micromol/l), the latter a selective ETA receptor antagonist. ETB receptor responsiveness was tested by sarafotoxin S6c (1-100 nmol/l) and IRL-1620 (0.1-10 nmol/l) concentration-response curves, obtained in the noradrenaline-precontracted MVB.

RESULTS

At 5 weeks of age, ET-1 induced a similar concentration-dependent contraction in SHRs and WKY rats, with an overlapping BQ-123 pA2 value (negative common logarithm of the antagonist that produces an agonist dose ratio of 2) in the two strains. Indomethacin was ineffective in both groups. Sarafotoxin S6c and IRL-1620 both evoked an ETB-mediated, significant relaxation, only in WKY rats. In 12-week-old SHRs, ET-1 evoked a markedly increased maximal effect compared with the response in WKY rats (P< 0.01); this was prevented by treatment with indomethacin. The BQ-123 pA2 value was higher in SHRs than in WKY rats (P< 0.01). Both sarafotoxin S6c and IRL-1620 evoked a significant concentration-dependent relaxation in WKY rats, which was not detected in SHR preparations.

CONCLUSIONS

Our results could suggest that the different responses evoked by ET-1 in the MVB of SHRs during the onset of hypertension may be related partially to primary alterations in the ET-1 receptorial pattern and partially to the onset of high blood pressure, leading to an impairment in the haemodynamic balance.

Correlation between shape and electronic states in nanostructures

We show how the electronic states of quantum wires and quantum dots can be evaluated exactly starting from the profile of the nanostructure observed by transmission electron microscopy, scanning tunneling microscopy and atomic force microscopy. The calculated quantization energies reproduce the energy position of the luminescence resonances in the optical spectra of different samples, without fitting parameters.

Cardiovascular autonomic function in patients with primary achalasia

Impaired gastrointestinal function outside the esophagus has been found in achalasic patients. Moreover, achalasia may occur in diseases in which a systemic dysautonomia is evident. These findings raise the question of whether a generalized subclinical alteration of autonomic control is also present in primary achalasia. Cardiovascular reflex tests and power spectral analysis of heart rate variability were studied in patients with primary achalasia to establish whether autonomic nervous system changes are present in districts other than the gastrointestinal tract. Nineteen normotensive patients with untreated primary achalasia and with no history of cardiac, renal, or endocrinological diseases were examined. Cardiovascular reflex tests included: the tilt test (10 min at 65 degrees), Valsalva maneuver (40 mm Hg for 15 sec), deep breathing (6 breaths/min), and sustained handgrip (30% of maximal effort for 5 min). The parameters evaluated were systolic and diastolic blood pressure (continuously recorded), ECG, oronasal and thoracic respiration, tachogram, and plethysmogram. To evaluate the balance between parasympathetic and sympathetic functions, power spectral analysis of the heart rate variability was carried out. Each patient was paired with two sex- and age-matched healthy controls. In achalasic patients the head-up tilt test, Valsalva maneuver, deep breathing test, and sustained handgrip did not show significant differences from the control group. Low-frequency (LF) and high-frequency (HF) spectral powers and the ratio of LF to HF did not differ in both groups. This study failed to disclose impaired cardiovascular autonomic control in achalasic patients. We suggest that in primary achalasia the defect is limited to the gastrointestinal tract.

Effects of erythromycin on human colonic circular muscle in idiopathic chronic constipation

BACKGROUND

Erythromycin has been shown to have profound prokinetic effects on the gastrointestinal tract of humans and animals, probably through its action on endogenous motilin receptors. The purpose of this study was to determine both the direct and indirect effects ('off contraction') of erythromycin and motilin on ex vivo circular muscle strips of the distal colon from patients with or without idiopathic chronic constipation (ICC).

MATERIALS AND METHODS

Cumulative concentrations of erythromycin (1-20 microM) and motilin (0.05-1 microM) were tested in both control and ICC preparations in order to evaluate the direct drugs effect. A range doses of both erythromycin (0.5-10 microM) and motilin (0.05-0.5 microM) were tested on their ability to affect the off-contraction that follows the typical inhibitory response evoked by low frequencies of Electrical Field Stimulation (EFS) (1-5 Hz, 20 V, 1 msec pulse trains lasting 1 min).

RESULTS

The direct effect of both erythromycin and motilin was a slight increase (less than 10% of the maximal ACh-induced contraction) in the basal tension, with no dose-response relationship. The off-contraction, evoked by EFS, was not affected by drugs pretreament in control preparations. Conversely, in ICC preparations both drugs significantly increased the off-contraction (about 30%).

CONCLUSIONS

Erythromycin causes mainly an indirect contractile effect in circular muscle strips from ICC patients. This effect may be related to the activation of inhibitory neuronal motilin receptors. This activation might potentiate NANC relaxation, proportionally increasing the circumferential reflex contraction that follows the EFS-induced relaxation.