Search

Aims: In hospitals, surfaces are often colonized by potentially pathogenic micro organisms which can remain alive for long periods of time, thus playing a major role in hospitalacquired infections. One way to overcome this drawback could be to use disinfectants with long-term action. Recent studies have shown that not only do disinfectants containing silver present an immediate effect, reducing the surface bacterial load, but that this action also appears persistent in time. This work assesses the bactericidal activity of a long-lasting disinfectant complex composed of silicon oxide, silver ions and a cationic surfactant (BACTERCLINE ENERGY BLAST) applied on the surfaces of two surgery ward rooms and left in place for different amounts of time (15 min and 72 hours). Study Design: An experimental study. Place and Duration of Study: The investigation was carried out in two rooms of a surgical ward at the Villa Erbosa health care facility in Bologna (Italy) over a period of seven weeks. Methodology: The samples were taken using contact plates (diameter: 24 cm2) containing an adequate agar culture medium (Tryptic Soy Agar). After incubation at the temperature of 36±1ºC for 24 and 48h, the number of colonies was counted and the statistical analysis of results was performed. Results: The product was able to achieve a high degree of decontamination (around 90%) immediately after application and that, after 72 hours, decontamination remained at about 55%. The results are statistically significant. Conclusion: It may be concluded that the tested product could be profitably used to decontaminate surfaces in hospital wards.

Objective: The purpose of the present research was to compare the residual microbial load in Solo System microfiber mops with silver and in normal microfiber mops without silver to see whether those with the silver prevent bacterial proliferation and spread more effectively during normal cleaning operations. Methods: Mops with and without silver were experimentally contaminated with suspension of Staphylococcus aureus ATCC 6538. The bioburden was evaluated by a filtering procedure according to UNI EN 1174 after contamination, after washing and after different times of impregnation in an alcohol-base detergent. Results and discussion: The results obtained lead to the conclusion that silver microfiber mop was significantly more effective in reducing bacterial load despite initial high level contamination (106-107 CFU/50 cm2). Indeed, after low temperature washing, the bacterial load was already completely eliminated while the mop without silver still presented relatively high levels of the microorganism (approximately 102 CFU/50 cm2) even after being soaked for 8 hours in a detergent/disinfectant. Keywords: decontamination, surface-active agents, products with antimicrobial action, semi-colon, infection control

Objective: This study analyzed how effectively bacteria penetrate through a new filtering device (Muski™) aimed at providing temporary protection against hazardous air contaminants. Materials and methods: A 1.5–7×108 cfu/ml bacterial or spore suspension was aerosolized. Fragments of the Muski filter, previously sterilized by gamma rays, were placed in a sterile stainless steel Seitz filter holder, plugged into an Erlenmeyer vacuum flask connected to a vacuum pump to force the bacteria aerosol through the Muski filter. As a control the same apparatus was used without the Muski filter. To evaluate the bacteria passing through the apparatus, diluent solution was introduced in the Erlenmeyer flask, which was then subjected to mechanical shaking. Both the contents of Erlenmeyer flask and the diluent solution, used to rinse out the Erlenmeyer flask, were filtered through a membrane filtration apparatus. The filtration membrane was transferred to the surface of a Petri dish containing a suitable culture medium f...

The new centrol sterile supply Deportment (CSSD) of the University Hospital Authority St. Orsola-Malpighi Polyclinic was inaugurated in September 2010. The CSSD collects functions of diagnosis and treatment of high technological impact, such as emergency room, diagnostic imaging, operating blocks and intensive care. The intervention was executed by a service contract for the design, construction, management, operation and maintenance of the unique CSSD.

The new Surgery and Emergency Centre of the University Hospital Authority S. 0rsola-Malpighi Polyclinic of Bologna was inaugurated in September 2010. This is a technological building of about 25,000 m2, which includes the following functions: Emergency Department, Diagnostic lmaging, 0perating Blocks and lntensive Care Unit, as well as a new Central Sterile Supply Department for surgical instruments intended to serve the entire polyclinic.

Una nuova centrale di Steritizzazione dell'Azienda Ospedaliero Universitaria Policlinico S. Orsola Malpighi è stata realizzata all'interno del Nuovo Polo Chirurgico e dell'Emergenza. Occupa una superticie di circa 1.100 mq ed è stata dimensionata per poter gestire oltre 40.000 interventi/anno. L'Azienda ha posto come oggetto della gara di appalto la progettazione, realizzazione, gestione, conduzione e manutenzione della centrale di sterilizzazione, con lo scopo di ottenere un servizio in grado dirispondere in modo efficace ed efficiente alle esigenze di sterilizzazione dei dispositivi medici, nel rispetto delle normative vigenti. Nella nuova centrale è stata posta particolare attenzione ai flussi del materiale ed ai percorsi del personale, oltre che a tutti gli elementi necessari per garantire un elevato grado di comfort per gli operatori, come ad esempio la presenza di illuminazione naturale in tutti gli ambienti con presenza continuativa di personale.

È stato recentemente inaugurato il Nuovo Polo Chirurgico e dell’Emergenza all’interno dell’Azienda Ospedaliero-Universitaria Policlinico S.Orsola Malpighi di Bologna. L’intervento di realizzazione del Nuovo Polo Chirurgico, iniziato nel luglio del 2007 e ultimato il 30 settembre 2010, si inserisce in un piano di sviluppo dell’assetto edilizio, tecnologico ed urbanistico del Policlinico iniziato nel 1999, che prevede la concentrazione delle attività assistenziali e della ricerca e didattica in 7 poli edilizi coerenti con l’assetto dipartimentale del Policlinico con il fine di favorire l’integrazione interdisciplinare del percorso assistenziale e anche una maggiore efficienza gestionale. Il Polo Chirurgico e dell’Emergenza si sviluppa su 5 livelli fuori terra ed un interrato, è a pianta rettangolare con una superficie di circa 25.000 mq e contiene funzioni ad elevata intensità di cura: Pronto Soccorso, Diagnostica per Immagini, Blocchi Operatori (con 12 sale operatorie) e Terapie Intensive (con 22 posti letto), oltre ad una nuova Centrale di Sterilizzazione dei ferri chirurgici di circa 1.100 mq destinata a servire l’intero Policlinico.

Surgical hand disinfection (with an alcohol-based hand rub) and surgical handwash (with an antiseptic-based liquid soap) are accepted measures to reduce the risk for surgical site infections. The new European Standards allow a comparison of their antimicrobial efficacy. The bactericidal activity of surgical hand rubs [Sterillium and Softaman, (active ingredient=alcohols)] and handwashes [Derman plus (triclosan), Hibiscrub (chlorhexidine) and Betadine (PVP-iodine)] was tested according to the prEN 12054 suspension test using Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus hirae, and to prEN 12791 for the effect on resident skin flora in comparison with 1-propanol, 60% (v/v). All five products achieved a reduction of test bacteria within 3 min of >10(5)-fold so fulfilling prEN 12054. However, only Hibiscrub, Sterillium and Softa Man met the requirements of prEN 12791, giving a mean reduction of resident micro-organisms (immediate and sustained effect) which was not significantly lower than the reference alcohol (P>0.1; Wilcoxon matched-pairs signed-rank test). Sterillium was significantly more effective than the reference alcohol (immediate and sustained affect). Products for surgical hand disinfection may have equal antimicrobial activity in suspension tests but show large differences under practical conditions. Healthcare workers should not rely on results from suspension tests when deciding on a product for surgical hand disinfection.

A protocol for the disinfection of gastroduodenoscopes, retrograde cholangiopancreatography endoscopes and colonoscopes using endoscope washers is described. The process recommends initial manual washing with a disinfectant containing didecyldimethylammonium chloride, surfactants and enzymes, a second washing in the endoscope washer using a detergent associated with a bacteriostatic, fungistatic substance (benzoisothiazolone) and finally the use of a 2% glutaraldehyde product buffered at pH6. After treatment with 2% Steranios added to the washer, less than 1 micro-organism/ml liquid was found in the following units: 83% of the colonoscopes, 83% of the oesophagogastroduodenoscopes, 83% of the main channels of the retrograde cholangiopancreatography endoscopes and 75% of the auxiliary channels of the latter instruments. In 14% of the colonoscopes, 42% of the gastroduodenoscopes, 42% of the main and 50% of auxiliary channels in the retrograde cholangiopancreatography endoscopes there were no signs of microbial growth in the wash liquid. The results obtained indicated that this protocol allowed adequate disinfection of the endoscope channels, structurally the most difficult part of the instrument to disinfect. Emphasis is given to the degree by which instrument contamination can increase during overnight storage, suggesting that endoscopes need to be submitted to further disinfection after overnight storage. Moreover, the water flowing into the washers can also cause instrument recontamination, particularly during the final rinses. Therefore, to better safeguard the health of patients undergoing endoscopy, special care must be taken to maintain the filters and disinfect the washers themselves, no matter how effective the disinfection protocol used may be.

Gli autori in questo articolo analizzano da un punto di vista organizzativo le problematiche relative al percorso diagnostico-terapeutico del paziente con stroke. Al fine di consentire la più appropriata gestione di questi casi, nell’ambito del progetto di ristrutturazione dell’intera Azienda ospedaliera di Bologna Policlinico S. Orsola- Malpighi, è stato pianificato il nuovo pronto soccorso di terzo livello con la predisposizione architettonica ed organizzativa di una struttura capace di accogliere una efficiente stroke unit per acuti.

Two methods for cleaning waxed polyvinylchloride and porcelain grès hospital room floors were compared in order to determine their decontamination capacity: dry wiping followed by damp washing, and damp washing followed by dry wiping. Dry wiping followed by damp washing did not produce any significant reduction in the average bacterial load. However, damp washing followed by dry wiping reduced the bacterial load for both types of flooring. The difference was statistically significant.

The plasma GH response to GHRH (100 micrograms i.v.) was evaluated either alone or after pretreatment with pyridostigmine (120 mg orally 1 h prior to GHRH) in 9 younger men (age range: 22-39 years) and in 9 healthy elderly men (age range: 63-77 years). On a different occasion, subjects were tested with pyridostigmine alone. Basal concentrations of glucose, cortisol, androgens, estrogens, thyroid hormones and GH were similar in all subjects, whereas insulin-like growth factor was lower in elderly men. The GH response to GHRH was significantly lower in the older (mean peak was 6 times higher than baseline) than in the younger group (mean peak was 11.3 times higher than baseline). The pretreatment with pyridostigmine induced a striking increase in the GH response to GHRH in the younger subjects (mean peak was 26 times higher than baseline), whereas it produced only a slight increase in the GHRH-induced GH response in elderly men (mean peak was 8.7 times higher than baseline). When pyridostigmine was given alone, plasma GH levels rose significantly in both groups; however, the pyridostigmine-stimulated GH response was significantly higher in younger (mean peak was 6 times higher than baseline) than in older subjects (mean peak was 2.5 times higher than baseline). These data indicate that the cholinergic stimulatory regulation of GH release is reduced in elderly subjects. Since acetylcholine inhibits hypothalamic somatostatin release, the reduced cholinergic tone in elderly subjects may result in an increased somatostatinergic tone.

_ L'approccio per processi al fine dell'accreditamento dei servizi di pulizia e sanificazione ospedaliera. _ La relativa formazione del personale. _ I controlli di qualità e di processo. _ I controlli della dotazione e della metodologia. _ Le verifiche ispettive. _ La soddisfazione del cliente.

We have localized secretin in a morphologically distinctive endocrine cell scattered in the epithelium covering the villi and uppermost crypts of the human duodenum and jejunum. The human secretin cell was characterized by relatively large (mean diameter 299 nm +/- 69 SD), fairly irregular granules, the majority of which showed homogeneous distribution of secretin and chromogranin A immunolabelling in a structurally homogeneous core. Other granules had a targetoid pattern due to an inner, argyrophobe, secretin-immunoreactive body surrounded by an argyrophil, chromogranin A immunoreactive mantle. These targetoid granules represent a distinctive ultrastructural marker of the secretin cell. Secretin cell granules have been shown to react with chromogranin A antibodies and Grimelius' silver, while lacking chromogranin B immunoreactivity. About 1/3 of secretin cells also showed serotonin immunostaining.

Apennine geodynamic and geophysical evidences suggest models generating landslides affecting numerous Italian Regions, namely Emilia-Romagna, Marche, Umbria, Abruzzi, Molise and also Campania and Basilicata. These Adriatic Foredeep landslide models use concepts of Visco-Elasticity and Catastrophe Theory, recently including original contributions, i.e. Quasi-Sufficient Catastrophe Condition and Hopeless System. These models should be up-to-dated by processing field survey data and realtime Remote Sensing imageries, so using them like expert instruments helping civil protection organisations to alert people and protect natural and built environment.

Decontaminating mats made of several layers of adhesive sheets (water-based acrylic 6 g/m2) supplemented with a bactericidal agent (3-1 benzoisothiazolin) at a concentration of 25% were placed in the passages providing access to the operating rooms of an orthopaedic service. Contact plates containing tryptone soy agar were used to assess bacterial concentration at specific points in front of and beyond the mats. For trolley passageways two areas were defined: central and lateral paths, corresponding to the areas walked upon by the personnel pushing the trolleys and to the paths covered by the trolley wheels, respectively. In order to exclude a simple mechanical effect, a comparison of bacterial loads at defined sites beyond the mats was carried out in the presence and in the absence of decontaminating mats. Bacterial colony counts in the presence of decontaminating mats were substantially and statistically significantly reduced compared with the absence of mats. The lower mean number of colony-forming units detected at points located beyond the mats parallels this finding; this difference is also statistically significant. We thus conclude that decontaminating mats are potentially useful in decreasing micro-organism carry-over due to personnel or the passage of trolleys into areas at high risk of infection such as operating rooms.

To investigate percutaneous exposures to HIV in the highly active antiretroviral therapy (HAART) era, we performed an analysis of all percutaneous exposures reported from January 1994 to December 1998 in 18 Italian acute-care hospitals. Frequency and rate per 100 prevalent AIDS cases of HIV exposures decreased by 40% (from 4.3% to 2.6%, and from 1.0% to 0.6%, respectively; p0.001), which were mainly those related to the insertion/manipulation of peripheral vascular access devices (from 7.2% to 4.8%; p=0.05). We conclude that the benefits of HAART have changed the complexity of care required and therefore, the number and type of procedures performed on HIV patients that place the HCW at risk of injury.

The authors report a case of pineocytoma in a 44-year-old woman suffering from headache, vomiting and Parinaud syndrome. At histopathological examination the neoplasm showed a ill-defined lobulate pattern with some small pineocytomatous rosettes. The electron-microscopy revealed cells of moderate size and oval nuclei with smooth nuclear envelopes; well-developed organelles were found in the, abundant cytoplasm. The chromosome analysis revealed this kariotype: 58-59, XXX, -4, -5, -13, - 14, -15, + 19. This is the first report of a pineocytoma with ultrastructural and cytogenetic study; it confirms the literature findings of the electron-microscopy, whereas there is partial accordance with the previous cytogenetic studies.

The Viterbo Province, located in the Northern area of the Lazio Region is mainly characterised by an exceptional heritage given by centuries of Etruscan culture, well known all over the world. Beside that, many also Roman and Middle Age monuments - like e.g. Via Francigena: a Pilgrimage medieval rout to Rome - distinguish its landscape, which support both quite rich agricultural activities and high level tourism; also antique spas are enjoyed not only by population, owing to their historical and up-to-date reputation. Despite all this singular background, a Provincial landfill has been planned in this area, possibly also used by close Rieti Province. This paper is planning a number of actions to counteract such an ecological and environmental disaster.

The objective of this paper is to illustrate the hard problern to change a normal excavation executed for a building into reliable working areas/volumes for the exceptional archaeological finding of 17 (at least up to now.. ) Antique Roman Ships, close to Pisa-San Rossore Railway Station.

The Sanctuary of Monterosse has been re-located on the top of a clay hill close to the Terricciola (Pisa) after the big earthquake, which destroyed its Romanesque aspect. Now that Sanctuary is collapsing mainly because of the general hydro-geological evidences and the periodical behaviour of the water-table resting on the clay bedrock quite inclined downhill. The aim of this paper is to propose a synthetic summary of the activities directed to sauveguard and protect such a singular specimen of religious architecture in Western Tuscany. Under a broader point of view, this trend can be framed up in the sphere of activities wanting to contribute to the rescue of architectural buildings and constructions forrning the exceptional cultural heritage. This heritage is characterising bath the Tuscanian territory and the landscape, seen as precious and wise Environmental Resources to be preserved tor future generations, as far as it is still possible.

Visco-elastic landslides triggered by seismic phenomena along Adriatic slopes of the Apennine Ridge (Central Italy) are studied in the frame of L-Transfonn applications also accounting for oscillating aspects of their instabilitics (Bland 1960, Flugge 1967, Donnell 1976); starting from elementary one-dimensional model approaches towards two-dirnensional, various landslides representations are suggested and discussed.

Deep-rock visco-elasticity accounts for large-scale geophysical-geodynarnical modeIs in order to better represent evolutions of selected long-duration seismic crises: this natural hazard along ltalian Peninsula is considered a consequences of a sub-regional situation characterising Adriatic Foredeep.

Cerebral infarction is one of the three main causes of death in most countries. It is very frequent and, since it is more often disabiliting rather than fatal, it is of high social impact. The correct classification of patients and the accurate diagnostic definition of the various subtypes of stroke is of great prognostic and therapeutic importance since cerebral infarction is not a single entity. In this study we report our findings concerning 244 patients with embolic infarction recorded in the Parma Stroke Data Bank hospital register. Clinical features were studied (risk factors, symptomatology of the onset, degree of severity within 3 days of the onset, post-stroke complications) as were instruments readings (TAC) and evolution (outcome, mortality, personal performance and environmental integration, both 4 weeks after the clinical onset and after one year).

Three actual examples are given of important road-railways structures located along the Adriatic slope of the Apennine Ridge, connected with the so-called Adriatic Foredeep: more in detail these structure are a tunnel and related viaducts close to Arcuata del Tronto (Marche), an artificial road-tunnel near Cesena (Romagna) and a two-way railway-tunnel near Ortona (Abruzzo).

In an epidemiological research about stroke, we studied 235 patients with atherothrombotic brain infarctions and 81 patients with lacunes. It was a longitudinal study concerning patients admitted to our Medical Division during the acute phase and followed up for one year after the onset. We report some anamnestic data, the frequency of positive brain CT scan, main risk factors, symptoms at the onset, severity degree of the stroke within the first 72 hours, complications during, and outcome after, the first four weeks, including personal performances and environmental fitness, mortality rate and frequency of relapses. We also report some of these data after one year from the acute episode.

Data obtained in our experiments indicate that the microwave sterilization system utilized may be considered as a practical and rapid method for decontaminating steel surgical instruments. For the tested organisms (7 Gram- and 2 Gram+ genera) a 3' exposure time to microwaves provides successful sterilization. Microwave irradiation also had a killing action against Bacillus subtilis spores. A study by SEM of microwave treated spores shows typical morphological alterations of spore surfaces.

As atherosclerosis is a multi-systemic disease, each patient presenting clinical manifestation of atherosclerosis such as a stroke or RIND should be, from a vascular point of view, globally evaluated. The availability of Doppler ultrasound technique enables us to discover the presence of Peripheral Artery Disease (PAD) which is not always overt in the patient's history. Furthermore the presence of PAD is associated with a poorer prognosis in stroke patients.

A specific rabbit anti-human serum was used selectively to localize the aspartic proteinase cathepsin E to follicle associated epithelium (FAE) of human and rat intestine, including jejunum, ileum, appendix, colon and rectum, as well as of human palatine, pharyngeal and lingual tonsils. Coexpression of class II histocompatibility antigen HLA-DR antigen has been observed in some of the cathepsin E-positive epithelial cells. In addition, cathepsin E has been detected in a few mononuclear cells of intestinal lymphoid structures and tonsils resembling interdigitating reticulum cells of lymph nodes. Another aspartic proteinase, cathepsin D, has been found to be poorly represented in FAE and intensely expressed by macrophages. Electron immunocytochemistry localized cathepsin E to endosomal vesicles and endoplasmic reticulum of M cells in rat and human ileum as well as of M-like cells in human palatine tonsil. The results suggest a possible role of endosomal cathepsin E in the processing of macromolecules and microorganisms transported by M cells and related epithelial cells to mucosal associated lymphoid tissue (MALT).

A specific rabbit anti-human cathepsin E serum detected this aspartic proteinase in Langerhans cells of the skin, in interdigitating reticulum cells of lymph nodes and spleen and in histiocytosis X cells, but not in macrophages. Immunoblotting of tissue extracts confirmed the presence of cathepsin E in skin and lymph nodes. Electron immunocytochemistry with the protein A gold technique localized cathepsin E in the endoplasmic reticulum and in endosomal vesicles of both interdigitating and Langerhans cells, likely involving Birbeck bodies. A role of endosomal cathepsin E in antigen processing is suggested.

In the last years a great number of air quality simulation models have been developed and implemented into widely known computer packages. Presently, the major problem is to select in a rational way the model best suited for a specific situation. Hence, it seems useful to review and organize the knowledge about diffusion models into a computerized system to support the user in the appropriate choice. This means that the system has to provide to the user the expertise on air quality modelling which is necessary for the definition of the functional expression and parameter values corresponding to the characteristics of a specific site (i.e. sources, meteorology, terrain,…).

In 51 patients with gastric adenocarcinoma the fasting blood concentrations of hCG, beta hCG, alpha subunits, ADH, calcitonin, enteroglucagon, gastrin, GH, melatonin, somatostatin, estradiol, CEA and pepsinogen I in the peripheral vein were estimated by radioimmunoassay at the time of diagnosis and, in those who underwent surgery, 7 days after the operation, to determine the incidence of the modifications of the above mentioned substances' blood levels and the existence of possible markers. In presence of increases of the examined parameters greater than 50%, considering M +/- 2 SD of 10 control subjects as normal range, the tumours were examined immunohistochemically. In patients with gastric adenocarcinoma, in comparison with normal subjects, we found significant higher blood levels of hCG alpha subunits, gastrin and CEA and lower of melatonin, pepsinogen I and GH. The immunohistological results demonstrated CEA in both examined cases, alpha subunits in 2 of 6 (respectively in dysplasic areas and in surrounding non neoplastic mucosa) and enteroglucagon in 1 of 3 (dysplasic areas). Our results indicate that none of the parameters we examined, because of their non-specificity or of the low incidence of their modifications, can be considered a marker of gastric adenocarcinoma.

Myxedema coma is a rare manifestation of hypothyroidism, and its prognosis is usually poor. We report a case of myxedema coma due to transient pituitary hypothyroidism with complete clinical and endocrinological recovery. The possible vascular origin of the syndrome is discussed.

This paper describes the prototype of a decision support system oriented to air pollution network designers. The purpose is to help the users in the choice of the number and localization of instruments in an assigned area. The criterion employed is to locate instruments so as to evidence concentrations exceeding law standards. AREM runs on IBM PC's or compatibles and provides the following outputs: the number and the localization of the monitoring stations, their efficiency coefficient, the global network efficiency, and finally the station coverages. The user can change the constraints of the problem and examine the resulting different solutions. One example is shown for the town of Piacenza and its sorrounding industrial area, located in Northern Italy.

Eight different monoclonal antibodies which recognize at least three distinct epitopes unique to the lactase protein of human enterocyte have been used to investigate lactase protein expression in hypolactasia of Neapolitan adults by light and electron microscopy with the immunogold technique. All the antibodies gave the same results, namely: strong brush border staining in all the 7 lactase persistent adults tested; no staining at all in 9 of the hypolactasia subjects and a mosaic pattern of staining of enterocytes in other 12 adults with hypolactasia. The percentage of enterocytes showing intense staining for lactase protein varied between 4 and 20% of the total villus cells (mean value±SD:9.86±5.84). Intracellular staining was not apparent in any of the samples examined. Sucrase-isomaltase protein in contrast showed no mosaicism. The mosaic pattern of expression of lactase protein in some hypolactasic subjects suggests that columnar cells display a non homogeneous differentiation along the villus. If the two patterns, mosaicism or absence of detectable lactase protein, are present along the entire small intestine of the individuals tested, the results would suggest that two phenotypes of adult hypolactasia exist in the population we studied.

The pattern of differentiation of the enterocyte along the villus is considered to be dependent on the age of the cell and uniform in cells occupying comparable location on the villus. Using a polyclonal antibody against A blood group specific components of enterocyte brush border and three monoclonal antibodies we have demonstrated the expression of the A and B antigens in the brush border and Golgi apparatus of enterocytes of individuals of the expected blood groups, by light and electron microscopy, with the immunogold technique. The polyclonal anti-A serum was specific for the brush border whereas the monoclonal reagents also bound the endothelial cells and erytrocytes in the sections. Four of 16 blood group A individuals showed a mosaic pattern of expression of the A antigen, both with the polyclonal serum and the monoclonal anti-A reagent. Some enterocytes showed a normal staining and some other enterocytes at similar position on the villus showed no staining at all. An anti-Le a antibody showed that all the 4 individuals with the mosaic pattern were non secretor. Abnormalities of blood group antigens may reflect abnormal expression of glucosyl-transferase genes or disturbances of their acceptors. Enterocytes may therefore display a non homogeneous pattern of differentiation in morphologically similar cells occupying comparable location on the villus.