Exploring the human hair follicle microbiome.

Human hair follicles (HFs) carry complex microbial communities that differ from the skin surface microbiota. This likely reflects that the HF epithelium differs from the epidermal barrier in that it provides a moist, less acidic, and relatively ultraviolet light-protected environment, part of which is immune-privileged, thus facilitating microbial survival. Here we review the current understanding of the human HF microbiome and its potential physiological and pathological functions, including in folliculitis, acne vulgaris, hidradenitis suppurativa, alopecia areata and cicatricial alopecias. While reviewing the main human HF bacteria (such as Propionibacteria, Corynebacteria, Staphylococci and Streptococci), viruses, fungi and parasites as human HF microbiome constituents, we advocate a broad view of the HF as an integral part of the human holobiont. Specifically, we explore how the human HF may manage its microbiome via the regulated production of antimicrobial peptides (such as cathelicidin, psoriasin, RNAse7 and dermcidin) by HF keratinocytes, how the microbiome may impact on cytokine and chemokine release from the HF, and examine hair growth-modulatory effects of antibiotics, and ask whether the microbiome affects hair growth in turn. We highlight major open questions and potential novel approaches to the management of hair diseases by targeting the HF microbiome.

Extracellular Pax6 Regulates Tangential Cajal-Retzius Cell Migration in the Developing Mouse Neocortex.

The embryonic mouse cortex displays a striking low caudo-medial and high rostro-lateral graded expression of the homeoprotein transcription factor Pax6, which presents both cell autonomous and direct noncell autonomous activities. Through the genetic induction of anti-Pax6 single-chain antibody secretion, we have analyzed Pax6 noncell autonomous activity on the migration of cortical hem- and septum-derived Cajal-Retzius (CR) neurons by live imaging of flat mount developing cerebral cortices. Blocking extracellular Pax6 disrupts tangential CR cell migration patterns by decreasing the distance traveled and changing both directionality and depth at which CR cells migrate. Tracking of single CR cells in mutant cortices revealed that extracellular Pax6 neutralization enhances contact repulsion in medial regions yet reduces it in lateral regions. This study demonstrates that secreted Pax6 controls neuronal migration and distribution and suggests that it acts as a bona fide morphogen at an early stage of cerebral cortex development.

Genetic Otx2 mis-localization delays critical period plasticity across brain regions.

Accumulation of non-cell autonomous Otx2 homeoprotein in postnatal mouse visual cortex (V1) has been implicated in both the onset and closure of critical period (CP) plasticity. Here, we show that a genetic point mutation in the glycosaminoglycan recognition motif of Otx2 broadly delays the maturation of pivotal parvalbumin-positive (PV+) interneurons not only in V1 but also in the primary auditory (A1) and medial prefrontal cortex (mPFC). Consequently, not only visual, but also auditory plasticity is delayed, including the experience-dependent expansion of tonotopic maps in A1 and the acquisition of acoustic preferences in mPFC, which mitigates anxious behavior. In addition, Otx2 mis-localization leads to dynamic turnover of selected perineuronal net (PNN) components well beyond the normal CP in V1 and mPFC. These findings reveal widespread actions of Otx2 signaling in the postnatal cortex controlling the maturational trajectory across modalities. Disrupted PV+ network function and deficits in PNN integrity are implicated in a variety of psychiatric illnesses, suggesting a potential global role for Otx2 function in establishing mental health.

Genomics and outbreaks: foot and mouth disease.

Foot and mouth disease virus (FMDV) is an animal pathogen of global economic significance. Identifying the sources of outbreaks plays an important role in disease control; however, this can be confounded by the ease with which FMDV can spread via movement of infected livestock and animal products, aerosols or fomites, e.g. contaminated persons and objects. As sequencing technologies have advanced, this review highlights the uses of viral genomic data in helping to understand the global distribution and transboundary movements of FMDV, and the role that these approaches have played in control and surveillance programmes. The recent application of next-generation sequencing platforms to address important epidemiological and evolutionary challenges is discussed with particular reference to the advent of 'omics' technologies.

Le virus de la fièvre aphteuse est un agent pathogène affectant les animaux d'élevage, avec des conséquences économiques considérables à l'échelle mondiale. La détection des sources des foyers est un aspect important de la lutte contre cette maladie ; l'efficacité de cette stratégie est toutefois compromise par la facilité avec laquelle le virus de la fièvre aphteuse se propage à la faveur des mouvements d'animaux ou de produits d'origine animale infectés, d'aérosols ou de personnes ou matières contaminées. Les auteurs décrivent, au fur et à mesure des avancées des technologies du séquençage, les données de la génomique virale qui ont permis de mieux comprendre la distribution mondiale et la propagation transfrontalière du virus de la fièvre aphteuse et le rôle que ces approches ont commencé à jouer dans les programmes de contrôle et de surveillance. Les auteurs examinent également les applications récentes des plates-formes de séquençage de nouvelle génération pour résoudre des problèmes épidémiologiques et évolutifs importants, en se référant particulièrement à l'avènement des technologies dites «­omiques ¼.

El virus de la fiebre aftosa es un patógeno animal que reviste importancia planetaria. A la hora de combatir la enfermedad es útil poder determinar el origen de los brotes, tarea que sin embargo puede verse frustrada por la facilidad con que el virus es capaz de diseminarse siguiendo los desplazamientos de animales o derivados animales infectados o por aerosoles o fómites (por ejemplo personas u objetos contaminados). Los autores hacen hincapié en la utilización de datos de genómica vírica para ayudar a aprehender la distribución mundial y los movimientos transfronterizos del virus de la fiebre aftosa, lo cual es posible gracias a los avances que han conocido las técnicas de secuenciación, así como en la función que pueden cumplir estos métodos dentro de los programas de control y vigilancia. También examinan la reciente aplicación de dispositivos de secuenciación de próxima generación para abordar importantes problemas epidemiológicos y evolutivos, refiriéndose especialmente al advenimiento de las técnicas «ómicas¼.

Permeable Adsorptive Barrier (PAB) for the remediation of groundwater simultaneously contaminated by some chlorinated organic compounds.

In this paper, a Permeable Reactive Barrier (PRB) made with activated carbon, namely a Permeable Adsorptive Barrier (PAB), is put forward as an effective technique for the remediation of aquifers simultaneously contaminated by some chlorinated organic compounds. A design procedure, based on a computer code and including different routines, is presented as a tool to accurately describe mass transport within the aquifer and adsorption/desorption phenomena occurring inside the barrier. The remediation of a contaminated aquifer near a solid waste landfill in the district of Napoli (Italy), where Tetrachloroethylene (PCE) and Trichloroethylene (TCE) are simultaneously present, is considered as a case study. A complete hydrological and geotechnical site characterization, as well as a number of dedicated adsorption laboratory tests for the determination of activated carbon PCE/TCE adsorption capacity in binary systems, are carried out to support the barrier design. By means of a series of numerical simulations it is possible to determine the optimal barrier location, orientation and dimensions. PABs appear to be an effective remediation tool for the in-situ treatment of an aquifer contaminated by PCE and TCE simultaneously, as the concentration of both compounds flowing out of the barrier is everywhere lower than the regulatory limits on groundwater quality.

Characterization of the O/ME-SA/Ind-2001d foot-and-mouth disease virus epidemic recorded in the Maghreb during 2014-2015.

The O/ME-SA/Ind-2001d has been the main foot-and-mouth disease virus (FMDV) lineage responsible for FMD epidemics outside the Indian subcontinent from 2013 to 2017. In 2014, outbreaks caused by this FMDV lineage were reported in Maghreb, where it was initially detected in Algeria and Tunisia and later in Morocco. This was the first incursion of an FMDV type O of exotic origin in the Maghreb region after 14 years of absence. In this study, we report analyses of both VP1 and whole-genome sequences (WGSs) generated from 22 isolates collected in Algeria and Tunisia between 2014 and 2015. All the WGSs analysed showed a minimum pairwise identity of 98.9% at the nucleotide level and 99% at the amino acid level (FMDV coding region). All Tunisian sequences shared a single putative common ancestor closely related to FMDV strains circulating in Libya during 2013. Whereas sequences from Algeria suggest the country experienced two virus introductions. The first introduction is represented by strains circulating in 2014 which are closely related to those from Tunisia, the second one, of which the origin is more uncertain, includes strains collected in Algeria in 2015 that gave origin to the 2015 outbreak reported in Morocco. Overall, our results demonstrated that a unique introduction of O/Ind-2001d FMDV occurred in Maghreb through Tunisia presumably in 2014, and from then the virus spread into Algeria and later into Morocco.

Combining livestock trade patterns with phylogenetics to help understand the spread of foot and mouth disease in sub-Saharan Africa, the Middle East and Southeast Asia.

International trade in animals and their products is recognised as a primary determinant of the global epidemiology of transboundary diseases such as foot and mouth disease (FMD). As well as causing serious production losses, FMD is highly contagious, being transmitted through multiple routes and hosts, which makes it one of the most important diseases affecting trade in livestock. Its occurrence has dramatic consequences for the agricultural economy of a normally disease-free country, as well as for the livelihoods and income generation of developing countries where the disease continues to be endemic. In the dynamic of FMD virus (FMDV) dispersal across the globe, phylogenetic inference from molecular sequences of isolated viruses makes a significant contribution to investigating the evolutionary and spatial pathways underlying the source of FMD epidemics. Matching data on livestock movement with molecular epidemiology can enhance our fundamental understanding when reconstructing the spread of the virus between geographical regions, which is essential for the development of FMD control strategies worldwide. This paper reviews the global situation of FMD in the last ten years, combining phylogenetic insights with information on livestock production systems and international trade to analyse the epidemiological dynamics of FMD and the sources of FMDV introductions at a regional level in sub-Saharan Africa, the Middle East and Southeast Asia.

A procedure to design a Permeable Adsorptive Barrier (PAB) for contaminated groundwater remediation.

A procedure to optimize the design of a Permeable Adsorptive Barrier (PAB) for the remediation of a contaminated aquifer is presented in this paper. A computer code, including different routines that describe the groundwater contaminant transport and the pollutant capture by adsorption in unsteady conditions over the barrier solid surface, has been developed. The complete characterization of the chemical-physical interactions between adsorbing solids and the contaminated water, required by the computer code, has been obtained by experimental measurements. A case study in which the procedure developed has been applied to a tetrachloroethylene (PCE)-contaminated aquifer near a solid waste landfill, in the district of Napoli (Italy), is also presented and the main dimensions of the barrier (length and width) have been evaluated. Model results show that PAB is effective for the remediation of a PCE-contaminated aquifer, since the concentration of PCE flowing out of the barrier is everywhere always lower than the concentration limit provided for in the Italian regulations on groundwater quality.

An innovative in-situ DRAINage system for advanced groundwater reactive TREATment (in-DRAIN-TREAT).

The removal of groundwater contamination is a complex process due to the hydro-geochemical characteristics of the specific site, related maintenance and the possible presence of several types of pollutants, both organic and inorganic. In recent decades, there has been an increasing drive towards more sustainable treatment for contaminated groundwater as opposed to "intensive" treatments, i.e. with high requirements for onsite infrastructure, energy and resource use. In this study, a new remediation technology is proposed, combining the use of advanced drainage systems with adsorption processes, termed "In-situ reactive DRAINage system for groundwater TREATment" (In-DRAIN-TREAT). By taking advantage of the groundwater natural gradient, In-DRAIN-TREAT collects the contaminated groundwater via a drainage system and treats the polluted water directly into an active cell located downstream, avoiding external energy inputs. Preliminary results indicate the applicability and high efficiency of In-DRAIN-TREAT when compared with a permeable reactive barrier (PRB). In-DRAIN-TREAT is applied to remediate a theoretical aquifer with low permeability, contaminated by a 13 m wide hexavalent chromium (CrVI) plume. This is achieved in less than a year, via a drain DN500, 32 m long, a 30 m3 treatment cell filled with activated carbon and no energy consumption. A comparison with permeable barriers also shows a preliminary 63% volume reduction, with a related 10% decrease of remediation costs.

Experimental and simulation study of the restoration of a thallium (I)-contaminated aquifer by Permeable Adsorptive Barriers (PABs).

Permeable Adsorptive Barriers (PABs), filled with a commercial activated carbon, are tested as a technique for the remediation of a thallium (I)-contaminated aquifer located in the south of Italy. Thallium adsorption capacity of the activated carbon is experimentally determined through dedicated laboratory tests, allowing to obtain the main modelling parameters to describe the adsorption phenomena within the barrier. A 2D numerical model, solved by using a finite element approach via COMSOL Multi-physics®, is used to simulate the contaminant transport within the aquifer and for the PAB design. Investigations are carried out on an innovative barrier configuration, called Discontinuous Permeable Adsorptive Barrier (PAB-D). In addition, an optimization procedure is followed to determine the optimum PAB-D parameters, and to evaluate the total costs of the intervention. A PAB-D made by an array of wells having a diameter of 1.5m and spaced at a distance of 4m from each other, is shown to be the most cost-effective of those tested, and ensures the aquifer restoration within 80years. The simulation outcomes demonstrate that the designed PAB-D is an effective tool for the remediation of the aquifer under analysis, since the contaminant concentration downstream of the barrier is below the thallium regulatory limit for groundwater, also accounting for possible desorption phenomena. Finally, the best PAB-D configuration is compared with a continuous barrier (PAB-C), resulting in a 32% saving of adsorbing material volume, and 36% of the overall costs for the PAB-D.

Host-pathogen dynamics of squirrelpox virus infection in red squirrels (Sciurus vulgaris).

To improve our understanding of squirrelpox virus (SQPV) infection in the susceptible host, three red squirrels were challenged with wild-type SQPV via scarification of the hind-limb skin. All squirrels seroconverted to the infection by the end of the experiment (17 days post-challenge). Challenged animals suffered disease characterised by the development of multiple skin and oral lesions with rapid progression of skin lesions at the infection site by day 10 post-challenge. No internal pathological changes were found at post-mortem examination. A novel SQPV Taqman(®) Real-time PCR detected viral DNA from multiple organs, with the largest amounts consistently associated with the primary and secondary skin and oral lesions where viral replication was most likely occurring. Immunohistochemistry clearly detected viral antigen in the stratified squamous epithelium of the epidermis, tongue and the oropharyngeal mucosa-associated lymphoid tissue and was consistently associated with histological changes resulting from viral replication. The lack of internal pathological changes and the detection of relatively low levels of viral DNA when compared with primary and secondary skin lesions argue against systemic disease, although systemic spread of the virus cannot be ruled out. This study allowed a comprehensive investigation of the clinical manifestation and progression of SQPV infection with a quantitative and qualitative analysis of virus dissemination and shedding. These findings suggest two separate routes of SQPV transmission under natural conditions, with both skin and saliva playing key roles in infected red squirrels.

Analysis of covariation in an SH3 domain sequence alignment: applications in tertiary contact prediction and the design of compensating hydrophobic core substitutions.

We have analyzed sequence covariation in an alignment of 266 non-redundant SH3 domain sequences using chi-squared statistical methods. Artifactual covariations arising from close evolutionary relationships among certain sequence subgroups were eliminated using empirically derived sequence diversity thresholds. This covariation detection method was able to predict residue-residue contacts (side-chain centres of mass within 8 A) in the structure of the SH3 domain with an accuracy of 85 %, which is greater than that achieved in many previous covariation studies. In examining the positions involved most frequently in covariations, we discovered a dramatic over-representation of a subset of five hydrophobic core positions. This covariation information was used to design second and third site substitutions that could compensate for highly destabilizing hydrophobic core substitutions in the Fyn SH3 domain, thus providing experimental data to validate the covariation analysis. The testing of our covariation detection method on 15 other alignments showed that the accuracy of contact prediction is highly variable depending on which sequence alignment is used, and useful levels of prediction accuracy were obtained with only approximately one-third of alignments. The results presented here provide insight into the difficulties inherent in covariation analysis, and suggest that it may have limited usefulness in tertiary structure prediction. On the other hand, our ability to use covariation analysis to design stabilizing combinations of hydrophobic core substitutions attests to its potential utility for gaining deeper insight into the stability determinants and functional mechanisms of proteins with known three-dimensional structures.

The Pandora Project: results of the pilot study.

The Pandora Project was designed to develop a computer-assisted system to improve the appropriateness and effectiveness of hypertension treatment in clinical practice and to organize a database both for epidemiologic and economic assessments. The feasibility study was conducted by five general practitioners (GP) who enrolled 244 patients over a period of 6 months. The follow-up lasted 6 months. The computer system implemented provided a linkage among GP's office, hypertension unit, Ravenna Health Service databases, and a remote station. A total of 209 patients completed the follow-up period; 56% of patients were not normotensive despite the antihypertensive treatment. The prevalence of overweight, physical inactivity, and family history of high blood pressure and hypercholesterolemia was greater than 50%. Unplanned check-ups by GP occurred 9%. Six patients were admitted to the hospital eight times; 19 patients attended the casualty department 21 times. The mean total direct cost per patient was 567,800 Italian Lire (ITL) and increased to ITL 732,000 or to ITL 825,900 when lost productivity, calculated according to two different formulas, was added. This pilot study confirms the need and feasibility of implementing the Pandora Project in general practice in Ravenna.

[ANP in the cirrhotic patient. A clinical contribution]. / L'ANP nel paziente cirrotico. Contributo clinico.

Pathogenesis of ascites in patients affected by liver cirrhosis is still debated; humoral and haemodynamic factors can play a role. Plasmatic renin activity (PRA), plasmatic aldosterone (PA), atrial natriuretic peptide (ANP) plasma levels, blood Na, K, urea, urinary K and Na were evaluated in 14 patients affected by liver cirrhosis (11 males and 3 females, aged from 38 to 62 years), 8 of them with ascites. The results were compared with those obtained in a control group poised to age and sex to the experimental group. 4 out of 14 patients suffering from ascites unresponsive to medical treatment were submitted to peritoneal venous jugular shunt (PVGS) and blood samples for PRA, PA and ANP were withdrawn immediately before, 4, 8 hours following surgery. The patients affected by liver cirrhosis without ascites showed PRA and PA levels similar to those observed in the control group, while ANP plasma levels were significantly higher (50.6 + 9.6 vs. 39.7 + 9.5 Pg/ml) (p < 0.02). In patients with ascites ANP, PA and PRA levels were higher than those observed in non ascites patients (ANP = 147.8 + 97.3 vs. 50.6 + 9.6 pg/ml; PA = 20.6 + 2.7 vs 7.8 + 0.8 ng/dl; PRA = 4.48 + 0.5 vs 1.9 + 0.34 ng/ml/h). In patients submitted to PVGS, PA and PRA levels were reduced 4 and 8 hours following the surgery, while ANP levels showed significant increase. A natriuretic and diuretic response has been observed even in the absence of ANP plasma levels variations.(ABSTRACT TRUNCATED AT 250 WORDS)

B scanning evaluation of irritant reactions with binary transformation and image analysis.

In order to characterize and quantify irritant skin reactions, 12 women aged 18 to 45 underwent 5 patch tests with sodium lauryl sulfate at the following concentrations: 0.5, 1, 2, 3 and 5%. The tests, applied on volar forearm skin, were removed after a 24-h application. Evaporimetry and B scanning were carried out at the beginning and at 24, 48 and 72 h after patch test application. Echographic recordings were performed by Dermascan C (Cortex Technology, Hadsund, Denmark). After the acquisition, the echographic images were processed by a dedicated software (Dermavision 2D, Cortex Technology, Hadsund, Denmark) enabling the selection of amplitudes of interest and the transformation into a binary colour system. By attributing one colour to a selected amplitude band, part of an image can be highlighted and assessed by a value corresponding to the number of pixels (picture elements). For the evaluation of the images, 2 bands were chosen. The first, ranging from 201 to 255 is able to highlight hyperreflecting parts of the pictures (epidermis, lower part of the dermis); the second, ranging from 0 to 30, marks the hypo-echogenic part of the tissue, which is the site of inflammation. The evaluation by means of the 201-255 amplitude band showed a marked decrease of the echogenicity of the epidermis which was more pronounced at 24-h determinations and for higher concentrations of sodium lauryl sulphate (SLS), whereas the increase in pixel numbers, shown by the 0-30 band, was slight and apparent only for high SLS concentrations. Echographic data and transepidermal water loss (TEWL) values showed a good correlation.(ABSTRACT TRUNCATED AT 250 WORDS)

B scanning evaluation of allergic reactions with binary transformation and image analysis.

In order to characterize and quantify allergic skin reactions, 12 nickel sensitized women aged 18 to 45 underwent 5 patch tests with nickel sulfate in petrolatum at the following concentrations: 0.5, 1, 2, 3 and 5%. The tests, performed on volar forearm skin, were removed after a 24-h application. B scanning evaluations were carried out at the beginning and at 24, 48 and 72 h after patch test application using Dermascan C (Cortex Technology, Hadsund, Denmark). After obtaining echographic images, there were processed by a dedicated programme (Dermavision 2D, Cortex Technology, Hadsund, Denmark) enabling the selection of amplitudes of interest and the transformation into a binary colour system. By attributing one colour to a selected amplitude band, part of an image can be highlighted and assessed by a value corresponding to the number of pixels (picture elements). For the evaluation of the images, 2 bands were chosen. The first, ranging from 201 to 255 is able to highlight hyper-reflecting parts of the pictures (epidermis, lower part of the dermis); the second, ranging from 0 to 30, marks the hypo-echogenic part of the tissue, which is the site of inflammation. This method showed a progressive increase in the number of low reflecting pixels according to the nickel patch test concentration and to the elapsing of time. On the contrary, at 24 h there was a decrease in pixel values concerning the hyper-reflecting band. This evaluation method proved useful in assessing the intensity of patch test responses.

[Surgical repair of pectus excavatum by internal metal strut fixation. Clinical experience in 51 cases]. / Riparazione chirurgica del petto escavato mediante fissazione interna con barre metalliche. Esperienza clinica su 51 casi.

BACKGROUND: Broad is the spectrum of congenital chest wall deformities. Fortunately the severe life-threatening deformities (i.e. ectopia cordis and Jeune's disease) are rarer than the more frequent pectus excavatum and carinatum. Funnel chest is the most common anterior chest wall deformity, it results from posterior depression of the sternum and cartilages, from the third to the eighth; it occurs more frequently in boys than in girls (4:1 ratio). While the deformity may be recognizable at birth, especially during crying spells, it progressively worsens during childhood, producing, sometimes, respiratory and cardiac impairment. METHODS: The authors report their experience, from April 1970 to December 1998, in correction of Pectus Excavatum using a single surgical technique, at the Borgo Roma Hospital of Verona. During this period 51 patients (mean age 14 years) affected by this deformity, were treated performing a sterno-chondroplasty with internal fixation. Most of the patients (94%) required operation for the esthetic and psychological reasons only. The grade of funnel chest (according to the Chin Classification) was: type I in 59.6% of patients, type II in 31.4% and type III in 11.7%. The surgical technique consisted in the modification of the Ravitch's technique (subperichondrial cartilage resection, transverse osteotomy with internal stainless steel strut fixation). We considered the intervention advisable to correct an existing defect or to prevent its progression. We don't think, in fact, that spontaneous recession of the deformity may occur. RESULTS: The follow-up varied from 4 to 18 years. The result was classified according to the classification of Humphreys and it was excellent in 64.7%, good in 17.7%, fair in 9.8% and poor in 7.8%. CONCLUSIONS: This technique proved to be safe and effective, it can be performed with no mortality, very low complication rate and satisfactory results.

[VIPoma: surgical treatment]. / VIPoma: trattamento chirurgico.

This paper reports a case of pancreatic VIPoma with widespread hepatic metastasis which was treated for approximately 2 years with a synthetic somatostatin analog (SMS 201/995). The treatment of choice in cases in which the tumour was fully removable is surgical resection. This occurred rarely since approximately 80% of VIPomas are malignant and are operated late when local infiltration is already widespread; in addition, 50% of cases are already metastasised at diagnosis. In this case, due to the infiltration of the superior mesenteric artery by the primary tumour it was necessary to carry out a left pancreasectomy which included two-thirds of the neoplastic mass. This was justified by slow tumour growth and also facilitated control of diarrhea and ensured a greater efficacy of possible postoperative chemotherapy. The use of synthetic somatostatin analog (SMS 201/995) enabled diarrhea to be satisfactorily controlled and is therefore specifically indicated for this type of tumour. NSE serum assay (neuron specific enolase) allowed the evolution of disease to be monitored during follow-up.

[Sentinel lymph node for breast cancer: remove less to know more]. / Il linfonodo sentinella nel cancro della mammella: rimuovere di meno per sapere di più.

BACKGROUND: Our aim was to study the value of sentinel lymph node (SLN) biopsy in patients with breast cancer seen at a community hospital. METHODS: Consecutive cases receiving primary treatment for unicentric breast cancer less than 3 cm in diameter were prospectively studied from January 1999 to July 2000. All patients signed a detailed informed consent. The majority of patients (89%) underwent a combined technique of intradermal injection of 0.3-1.2 mCi of (99)Tc and 1-3 cc of Patent Blue at the biopsy site. Intraoperative localization was performed with a hand-held gamma probe. The first 15 patients underwent routine back-up lymphadenectomy. Thereafter, only patients with positive SLN, suspicious findings, or personal preference underwent formal axillary dissection. RESULTS: One hundred eight cases were included in the study with a median age of 61 years and a median diameter of the breast tumor of 1.5 cm. Success rate for identification of SLN was 94% (101/108 cases). A total of 917 additional lymph nodes were removed after SLN biopsy (median 6.5 lymph nodes/patient). Correlation between SLN and the final axillary status was 98%. In 20/36 patients (61%) with positive axillary status the sentinel lymph node was the only positive one. Ten patients had only microscopic foci of cancer found in the SLN. Sixty-seven patients (62%) could have avoided axillary dissection becouse the SLN was found, it was negative, and there were no other intraoperative suspicious findings. CONCLUSIONS: SLN biopsy is accurate and easily reproduced. Our data confirms that the majority of breast cancer patients may no longer need routine axillary lymphadenectomy.