Treatment of discontinuous emission of sewage sludge odours by a full scale biotrickling filter with an activated carbon polishing unit.

A SULPHUSTM biotrickling filter (BTF) and an ACTUSTM polishing activated carbon filter (ACF) were used at a wastewater treatment plant to treat 2,432 m3·h-1 of air extracted from sewage sludge processes. The project is part of Thames Water's strategy to reduce customer odour impact and, in this case, is designed to achieve a maximum discharge concentration of 1,000 ouE·m-3. The odour and hydrogen sulphide concentration in the input air was more influenced by the operation of the sludge holding tank mixers than by ambient temperature. Phosphorus was found to be limiting the performance of the BTF during peak conditions, hence requiring additional nutrient supply. Olfactometry and pollutant measurements demonstrated that during the high rate of change of intermittent odour concentrations the ACF was required to reach compliant stack values. The two stage unit outperformed design criteria, with 139 ouE·m-3 measured after 11 months of operation. At peak conditions and even at very low temperatures, the nutrient addition considerably increased the performance of the BTF, extending the time before activated carbon replacement over the one year design time. During baseline operation, the BTF achieved values between 266-1,647 ouE·m-3 even during a 6 day irrigation failure of the biofilm.

Control of VOC emissions from a flexographic printing facility using an industrial biotrickling filter.

The study of an industrial unit of biotrickling filter for the treatment of the exhaust gases of a flexographic facility was investigated over a 2-year period with the objective to meet the volatile organic compound (VOC) regulatory emission limits. Increasing the water flow rate from 2 to 40 m(3) h(-1) improved the performance of the process, meeting the VOC regulation when 40 m(3) h(-1) were used. An empty bed residence time (EBRT) of 36 s was used when the inlet air temperature was 18.7 °C, and an EBRT as low as 26 s was set when the inlet temperature was 26.8 °C. During this long-term operation, the pressure drop over the column of the bioreactor was completely controlled avoiding clogging problems and the system could perfectly handle the non-working periods without VOC emission, demonstrating its robustness and feasibility to treat the emission of the flexographic sector.

Multicenter study on multidisciplinary committees in advanced prostate cancer.

INTRODUCTION AND OBJECTIVE: Although Multidisciplinary Teams (MDTs) are recommended in the management of Advanced Prostate Cancer (APC), their functioning in real practice has been poorly evaluated. We carried out a multicenter study with the objective of evaluating the functioning of uro-oncology MDTs in 6 hospitals. MATERIALS AND METHODS: A descriptive cross-sectional study was performed. The level of Compliance with the Fundamental Quality Requirements (CFQR) of the MDTs was evaluated by means of a questionnaire filled out by the coordinators of the MDTs in each hospital. The information on the perspective of the members of the MDTs was evaluated through an anonymous survey. RESULTS: A high level of CFQR in MDTs was evidenced (75%), showing deficiencies in terms of protocol update, agendas, audits, and scientific production. The survey was answered by 62.32% of the 69 physicians surveyed (urologists, oncologists, radiation therapists, radiologists, and pathologists). The 88.4% consider the duration of the meetings appropriate. There are disparate opinions concerning the protection of the MDT meeting time as well as protocol update. Of the patients with APC presented at the MDTs meeting, 62,8% require intervention from two specialties. Only 50% of respondents believe that all CRPC cases are discussed and that there is a prior agenda. The decisions made by the MDTs are reflected in the clinical history in 65.1% and are binding only in 60.5% of the cases. Half of the respondents have not been trained in MDTs. Most participants (90.7%) agree on the fact that MDTs. convey benefits. CONCLUSIONS: The evaluations of the MDTs identify rectifiable deficiencies by modifying hospital inertia and care planning.

Influence of ground tire rubber on the transient loading response of a peat biofilter.

The effect of using ground tire rubber (GTR) as an adsorptive material in the removal of a 2:1:1 weight mixture of n-butyl acetate, toluene and m-xylene by using a peat biofilter under different intermittent conditions was investigated. The performance of two identical size biofilters, one packed with fibrous peat alone and the other with a 3:1 (vol) fibrous peat and GTR mixture, was examined for a period of four months. Partition coefficients of both materials were measured. Values of 53, 118 and 402 L kg(-1) were determined for n-butyl acetate, toluene and m-xylene in peat, respectively; and values of 40, 609 and 3035 L kg(-1) were measured for the same compounds in GTR. Intermittent load feeding of 16 h per day, 5 days per week working at an EBRT of 60 s and an inlet VOC concentration of 0.3 g C m(-1), resulted in removal efficiencies higher than 90% for both biofilters, indicating that the addition of GTR did not adversely affect the behavior of the bioreactor. Full removal of n-butyl acetate was obtained for both biofilters. GTR improved the removal of the aromatics in the first part of the biofilter, facilitating lower penetration of the toluene and m-xylene into the bed. A 31-day starvation period was applied and intermittent operation subsequently restarted. In both biofilters, high removal efficiencies after a re-acclimation period of two days were achieved. A shock loading test related to 1-h peaks of three- and four-fold increases in its baseline concentration (0.30 g C m(-3)) was applied in both biofilters. For the biofilter packed with the peat and GTR mixture, attenuation greater than 60% was observed in the maximum outlet concentration when compared to the biofilter packed with peat alone.

Study of the interactions between penicillium oxalicum currie & thom and alternaria alternata (fr.) keissler.

The aim of this research was the analysis of the possible antagonistic effect of Penicillium oxalicum over the pathogen rice fungus A. alternata under different conditions of temperature, water activity and culture media. The macroscopic study of the dual growth revealed that according to the Index of Dominance P. oxalicum was more competitive that A. alternata at 25°C whereas at 15°C was this species. Microscopic analysis showed that P. oxalicum was a mycoparasite of A. alternata at all conditions tested. The antagonist penetrated into A. alternata and disintegrated its conidiophores and conidia. The results suggests that P. oxalicum may be a possible biological control agent of the rice pathogens in a future.

Suppression of Nigrospora oryzae (Berk. & Broome) Petch by an aggressive mycoparasite and competitor, Penicillium oxalicum Currie & Thom.

The objective of this research was to study by means of different techniques, the interaction between Penicillium oxalicum and Nigrospora oryzae under different temperatures (15 and 25 degrees C), water activities (0.95, 0.98, and 0.995) and culture media (rice and rice extract agar). In dual culture, P. oxalicum was dominant over N. oryzae in spite of presenting in the majority of cases, lower growth rates. The microscopic study revealed that P. oxalicum is a powerful mycoparasite, which attacks the conidiophores and the spores of N. oryzae, not only surrounding them, but also penetrating, deforming, destroying and developing reproductive structures inside them. The antagonist did not change its way of performance in the different tested conditions. Water activity and temperature showed a significant effect on fungus growth.

Renal donor implication in the origin of BK infection: analysis of genomic viral subtypes.

UNLABELLED: BK virus (BKV) reactivation in immunocompromised kidney transplant patients can produce a tubulointerstitial nephropathy (BKVN). Molecular tools that test for DNA-BKV provide early detection and assist in management, but some aspects of the pathogenesis of this infection, such as donor causality, remain unclear. MATERIALS AND METHODS: Between November 2004 and January 2006, 55 Spanish kidney donors were studied for BK infection. A quantitative PCR assay was performed on urine and serum to detect BKV. To determine the origin of the viral infection, a transcription control region of the BK polymorphism sequence was designed to identify the viral subtype. RESULTS: Fifteen of 55 (27%) donors were BK-PCR positive: 13 in urine and 2 in serum and urine. Moreover, monitoring of recipient pairs detected BK-PCR positivity in 14 of 73 recipients. We studied eight BK-PCR positive recipients (corresponding to four pairs) and their respective donors. The same viral genome was observed in the four pairs, namely, the A250-1-a, WW-like, AS, and JL genotypes. Interestingly, one of the four pairs showed the donor and the two recipients to display exactly the same JL genotype. CONCLUSION: On the basis of our preliminary results analyzing the molecular fingerprints of donor and recipient pairs, we have presented new data implicating the donor, in at least some cases, as the source of BK infection.

[Small cell carcinoma of the urinary bladder in a young man. A case report and literature review]. / Carcinoma vesical de células pequeñas en un varón joven. Presentación de un caso y revisión de la literatura.

Small cell carcinoma of the bladder is a rare entity characterized by an aggressive clinical behaviour with a high incidence of systemic metastases. We report a case of small cell carcinoma of the bladder in a young man. The primary local tumour was treated by radical surgery, pelvic radiation therapy and polychemotherapy according CDDP protocol. The patient died six months after surgery because disease progression. We also review and update the literature concerning this infrequently tumour.

A risk model for non-small cell lung cancer using clinicopathological variables, angiogenesis and oncoprotein expression.

BACKGROUND: The aim of this study was to investigate new prognostic factors, by using a prognostic model, that could help to identify the patient group with the greatest probability of death. PATIENTS AND METHODS: First, the clinicopathological variables were analyzed. Second, microvessels were immunohistochemically (IHC) stained with factor VIII-related antibody and then counted in the most intense vascularization area or hotspot, using an automatic image analyzer. In addition, biological angiogenesis-related factors such as vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase expression (iNOS) were also studied. Finally, we evaluated the IHC expression of p53 and p21WAF1 tumor supressor proteins. RESULTS: The significant independent predictors were: tumor size (p=0.0063), angiogenesis (p=0.0271) and p21WAF1 (p=0.0478). Thus, the most important factor was tumor size 2.7462 [95% CI=1.3307-5.6673]. Finally, these variables were included in a risk model, in order to identify the group with the highest associated probability of death. CONCLUSION: The analysis of several prognostic factors could establish a more accurate patient risk profile.

Polymerase chain reaction detection of BK virus and monitoring of BK nephropathy in renal transplant recipients at the University Hospital La Fe.

INTRODUCTION: Reactivation of BK infection occurs in immunocompromised hosts causing tubulointerstitial nephropathy (BKVN). Approximately 5% of kidney transplant recipients (KTR) develop BKVN, special half of whom lose their grafts. However, BKVN morphologic diagnosis on a renal biopsy is complicated, because the cytopathic changes can sometimes mimic rejection. Thus, BKV DNA-polymerase chain reaction (PCR) assay on serum, urine, and renal tissue is useful for early detection and monitoring of BKV. MATERIALS AND METHODS: We performed routine monthly urine cytologies looking for decoy cells as a marker of virus replication. Then, we performed a qualitative PCR on urine and serum in all recipients (independently of positive or negative cytology). We amplified 3 BK viral genome regions, LT (early transcription region) and VP1 (late transcription region) seeking a more accurate virus detection, and the TCR (control transcription region) region to perform a polymorphism sequence analysis to identify the BK genomic variant. Finally, the BKVN diagnosis was confirmed using renal biopsy. RESULTS: At present, 132 patients have been monitored. Thirteen of 40 (33%) were PCR-urine-positive cases (5 LT+/VP1- and 8 LT+/VP1+), and 10 of 132 (7.5%) were PCR-serum-positive cases (7 LT+/VP1- and 3 LT+/VP1+). When we compared PCR-urine and cytology results, 11 of 40 (27.5%) patients showed a positive cytology, 6 of whom were PCR- urine-positive (1 LT+/VP1- and 5 LT+/VP1+); whereas, 29 patients showed a negative cytology, 7 of whom were PCR-urine-positive(3 LT+/VP1- and 4 LT+/VP1+). Thus, comparison of PCR- urine and cytology results revealed false-positive and false-negative cases. Finally, TCR sequence analysis was performed in 9 patients to identify the BK genomic variants. CONCLUSION: Testing for BKV DNA in urine and serum is a noninvasive early detection assay and monitoring tool.

Ameloblastoma. Diagnosis by means of FNAB. Report of two cases.

INTRODUCTION: Ameloblastomas are the most frequent odontogenic tumors of the maxilla. In spite of their benign cytohistological appearance, they behave as invasive recurring tumors, with the possibility of metastasis. FNAB is a rapid, bloodless test that provides a pre-surgical diagnosis, thus, on occasions avoiding the need for diagnostic biopsies. We present the cytological characteristics of two cases of jugal recurrences of mandibular ameloblastomas diagnosed by FNAB, as well as their cytohistological correlation. CLINICAL CASES: Two patients, a 36-year-old woman, and a 62-year-old male who both attended with mandibular swelling of a few months evolution. In both cases the first diagnostic approximation was the histological study of the tumoral mass, together with the radiological studies. Following therapeutic extirpation both cases recurred. The diagnosis of the recurrences was established cytologically by means of FNAB. The cytologic smears revealed a granular background with isolated macrophages and giant multinucleate cells and an abundant epithelial cellularity of basaloid appearance arranged in cohesive groups forming images of peripheral palidasing, as well as small groups of squamous metaplastic cells. DISCUSSION: FNAB is considered to be a rapid, bloodless and reliable method for the diagnosis of ameloblastoma. The cytology of these tumors reveals components of the lesion that, in general, are sufficient for the diagnosis of ameloblastoma, especially in cases of recurrence.

[Comparison of diferents suburethral slings for the treatment of stress urinary incontinence]. / Estudio comparativo de diferentes procedimientos de sling suburetral para el tratamiento de la incontinencia urinaria de esfuerzo.

OBJECTIVES: To compare the results of the different procedures of sling suburetral used in our service (TVT, Sparc, IVS, Obtape and Monarc) for the treatment of the female urinary incontinence. MATERIAL AND METHODS: 96 patients retrospective analysis affects of female urinary incontinence and subjected to different procedures of sling suburethral without tension. The half age: 56.1 +/- 10.7 years. 75 patients were intervened by means of procedures retropubics (48 TVT, 17 Sparc, 10 IVS) and 21 with obturators (10 Obtape, 11 Monarc). The half time of pursuit: 26.3 +/- 12.7 months (29.4 months for the methods retropubics and 11.7 for the obturators). The analyzed variables were: age, obesity, grade of previous incontinence, type of used procedure, time of pursuit, and previous surgical procedures. We compare the complications and the results obtained with the different ones technical. RESULTS: the cure percentage was of 95.7%. 7 patients presented complications: one intestinal perforation, two bladders perforations, one erosion of vaginal wall, three incontinences of novo urgency. In 6 cases the stress incontinence persists. When analyzing the association between the diverse variables and the success, we appreciate that the variables with value presage were the age and the obesity (P < 0.05) not observing relationship with the technique employeed. CONCLUSIONS: The existence of multiple surgical approachs and a varied auxiliary materials allow each surgeon to choose that with the one that is more familiarized and comfortable without, seemingly, influence it in the results.

[Treatment of males with post-prostatectomy stress urinary incontinence by a mesh anchored to the ischio-pubic bones]. / Tratamiento de la incontinencia urinaria de esfuerzo post-prostatectomía radical mediante malla anclada a ramas isquiopubianas.

We presented the results of an alternative in the treatment of the stress urinary incontinence of male radical postprostatectomy. Is a technique of renewed interest in the last years, cradle in the procedure of Stamey, consisting of placing an on guard suburetral polypropylene mesh, anchored by means of screws to the isquiopubian branches. We have applied the procedure in 4 patients and with stress urinary incontinence of long evolution. After an average pursuit of 12.5 months, two patients present total continence, one has improved significantly and in the other the incontinence persists. There have been no postoperating complications nor rejection of the mesh. From these preliminary results and the reviewed bibliography, we thought that this technique can constitute an alternative to the artificial urinary sphincter, dices its clinical results, its facility of execution, the good tolerance and his low cost.

[Prognostic value for progression of the regulating proteins of the cellular cycle in PT1G3 bladder tumours]. / Valor pronóstico de progresión de las moléculas reguladoras del ciclo celular en tumores vesicales T1G3.

INTRODUCTION AND OBJECTIVE: Bladder tumor T1G3 constitutes the group of superficial tumors more aggressive. New prognostic factors in the field of the cytogenetics and molecular biology have been analyzed, with often contradictory results, being little the specific works in tumors T1G3. Our objective is to determine if in this group of tumors the immunohistochemical markers present predictive value of clinically useful progression, and therefore with validity to indicate more suitable a precocious therapeutic attitude. MATERIAL AND METHODS: Retrospective study of a series of 83 patients affected of bladder tumor T1G3, on which we analyzed a total of 14 variables; between the new predictive factors: the immunohistochemical determination of regulating proteins of the cellular cycle: p53, p21 and bcl-2, as well as the Ki-67 protein like marker of cellular proliferation. By means of logistic regression analysis we establish the independent prognostic variables for tumorlike progression. RESULTS: The cut point established for Ki67 and p53 was 40% of inmmunomarked cells, 20% for p21 and 10% for Bcl-2. The univariant analysis showed different rates from progression and free times of progression based on the immunohistochemistry of Ki67 and p53: nevertheless, the logistic regression demonstrated that single the immunohistochemistry of p53 presented independent predictive value. CONCLUSIONS: The determination of p53 presents predictive value of clinically useful progression in bledder tumors T1G3, so that its determination can constitute a essential factor in the strategies of treatment of these tumors.

[Urological attendance in the Integral Health Center "Alto Palancia": model of primary-specialized integration and unique consultation]. / La asistencia urológica en el Centro Sanitario Integral "Alto Palancia": modelo de integración primaria-especializada y consulta única.

INTRODUCTION AND OBJECTIVE: The progressive increase in the demand of urological attendance demands to establish new welfare models that avoid the saturation of consultations and improve the quality in the attention to the user. The objective of this work is to analyze the improvement of the welfare activity developed in Integral the Sanitary Center Alto Palancia, after the restoration of new welfare models based on integration between Attention Primary and Specialized and the putting in practice of the denominated Unique Consultation. MATERIAL AND METHODS: We analyzed the characteristics of the Center, functions and activity of the specialty developed during year 2002. We described to the application of the model of Unique Consultation and the elements of integration with Primary Attention. We analyzed the improvement of the activity through indicators, that we compared with preceding years. In order to determine the degree of satisfaction of the users we made a survey of opinion of patients and/or taken care of relatives in the Center under the new welfare models. Finally we analyzed the advantages that the applied process presents for the patient and the own sanitary institution. RESULTS: 42% of patients have been taken care of by means of the model of Unique Consultation, being the predominant pathology the HBP in the man and the ITUs in the woman. The time of delay for first visit has been reduced from 49 days in single December 2001 to 3 in December 2002. Single 7.7% of patients discharged from the hospital for pursuit by Primary Attention have been sent again to the specialist. The time that the urólogo dedicates to consultations has reduced in a 29%, being this time dedicated to the accomplishment smaller surgery and final reconnaissances (echography, urodynamic studies and others). The opinion survey has shown a satisfaction of the user very elevated. CONCLUSION: The model of Integral Attention Primary-Specialized and the putting in practice of Unique Consultation applicable to the specialty of Urology, increasing the quality perceived by the user and with evident advantages for the Sanitary Organization.

[Predictive value of progression of muscularis mucosae and percentage G3 cells in vesical TIG3 tumours]. / Valor predictivo de progresin de la muscularis mucosae y del porcentaje de células G3 en tumores vesicales T1G3.

INTRODUCTION AND OBJECTIVE: Vesical tumor T1G3 constitutes the border between the superficial tumor and the infiltrante tumor. Some of these tumors do not respond to BCG and progress, with cystectomy that present poor results, patients who would benefit from a precocious and aggressive treatment if we could identify them in an preinvasive stage. New predictive factors try to select to these tumors, being little the works that consider anatomo-pathological meticulous study (substanding of the T1 in T1a and T1b and percentage of present G3 cells in the tumor). Our objective is to analyze the value of these anatomo-pathological considerations like predictive factors of progression. MATERIAL AND METHODS: Retrospective study of a series of 91 patient affection of vesical tumor T1G3 with initial treatment by means of RTU and BCG. We analyzed 12 variables. The new predictive factors: the level of invasion respect to muscularis mucosae and the percentage of G3 cells. By means of logistic regression analisys we establish the independent pronostic factors for tumoral progression. RESULTS: A total of 31 patients presented infiltration of detrusor, passing away 17 of tumoral cause, after an average time of pursuit of 57.8 +/- 28.2 months. In 8 cases (9%) the substanding could not be determined. The rate of progression for T1a tumors was of 20% (8/40) and for T1b 53% (23/43). Presented independent predictive value of progression the multiplicity (odds: 7.26), the size (odds: 2.14), the presence of Cis (odds: 1.42) and the subestanding (odds: 6.81). CONCLUSION: The substanding is a predictive factor of progression clinically useful in vesical tumors T1G3, reason why we considered habitual clinical introduction.

Liver disease as primary manifestation of multiple myeloma in a young man.

We report a 27-year-old man who presented with fatigue, moderate weight loss and progressive abdominal distension as primary manifestations of a light-chain multiple myeloma (MM). Liver scan showed an enlarged liver with multiple low attenuation areas. Liver biopsy revealed sinusoidal infiltration by small size cells identified as Kappa light chain-producing primitive plasma cells by immunohistochemistry. The patient responded to three courses of EDAP. Subsequently he received intensive therapy with busulfan/melfalan and a peripheral blood stem cell transplantation enriched for CD34+ cells from his HLA-identical brother. No acute graft-versus-host disease was detected. Now, 12 months after transplant, the patient is asymptomatic.

Counts and areas of S-100-positive epidermal dendritic cells in atypical molluscum contagiosum affecting HIV+ patients.

Molluscum contagiosum is a common and self-limiting viral infection, that in HIV+ patients courses as an opportunist affection with atypical clinical features. Impaired cell-mediated immune response could be involved in such atypical growth. We evaluated the density and area of Langerhans cells (LC) using S-100 immunohistochemistry in seven atypical molluscum contagiosum. LC density was quantified by three different methods using computer-assisted morphometry as well as estimating the relative area of LC with respect to epidermal area. Results were compared with two control groups (normal skin specimens and molluscum contagiosum affecting non-AIDS healthy patients). We found a virtual absence of LC in areas of molluscum lesions affecting both HIV+ and non-AIDS patients. Likewise we observed an evident decrease in LC density in perilesional epidermis of atypical molluscum with respect to both control groups. Upon comparing the counts and areas, we observed that this reduction in LC count was statistically significant only when considering LC related to length of basement membrane in atypical molluscum with respect to normal skin specimens. Our finding of a reduced number of LC in the perilesional epidermis of HIV+ patients with atypical molluscum could explain the high frequency and clinical challenge of molluscum contagiosum in immunocompromised people. In spite of these results, further studies of LC kinetics and functions are required to precisely elucidate their role in the course of molluscum contagiosum in HIV+ patients.

Immunohistochemical expression of Bcl-2 oncoprotein in EBV-associated nasopharyngeal carcinoma correlated to histological type and survival.

Expression of Bcl-2 is associated with inhibition of apoptosis and extension of cell survival. In vitro Bcl-2 protein expression is up-regulated by the EBV-latency associated antigen latent membrane protein (LMP-1). We have investigated the relationship between the presence of EBV-DNA screened by means of sensitive nested-PCR, nasopharyngeal carcinoma (NPC) histological types according to two different schemata (WHO and Micheau classifications) and Bcl-2-124 immunohistochemical expression in 55 biopsy samples of NPC. EBV genome was detected in 100% of samples with sufficient DNA quality to support the previous view that all types of NPC are variants of EBV-infected neoplasia. Bcl-2 was observed in the basal layer of normal nasopharyngeal mucosa and also at cytoplasmic level in 42 of 55 (76.4%) NPC cases. Mitotic neoplastic cells usually showed strong cytoplasmic and chromosomal staining, a finding not well referred to previously. Bcl-2 expression was significantly associated (p<0.05) to undifferentiated NPC (UNPC) when a histological classification with only two major microscopical types was applied. No close correlations were found between the presence of EBV-DNA, NPC location, clinical stage and age or sex of the patients in relation to Bcl-2 positive expression. However, when comparing Bcl-2 expression and known survival mean of the patients, significant differences were observed (p<0.001) so that mean survivals were 31.1, 24.4, 52.2 and 54.1 months respectively for NPC patients with -, +, ++ and Bcl-2 immunoreactivity. Nevertheless this better clinical outcome in Bcl-2 NPC positive cases may depend on the histological type due to close relationship with UNPC. Only studies of larger series with long-term follow-up and multivariate analyses may document whether Bcl-2 expression is an independent prognostic marker in the evolution of NPC patients.

Comparative analysis of Epstein-Barr virus (EBV) detection by nested-PCR and non-isotopic in situ hybridization in nasopharyngeal carcinoma (NPC).

The aims of this study were two-fold: first, to assess the relative diagnostic performance of non-isotopic in situ hybridization (ISH) and the nested polymerase chain reaction (nested-PCR) applied to Epstein-Barr virus (EBV) detection in a series of 55 unselected nasopharyngeal carcinoma (NPC) cases and, secondly, to correlate these data with histopathological classification. Our study shows that in 76.36% of NPC cases positive nuclear signals were observed using EBV-ISH. Overall, EBV-ISH positivity varied according to histological type, in that undifferentiated carcinomas showed a higher proportion of positive cases than differentiated cell carcinomas, although ISH results do not show significant differences in relation to histological types when employing two different schemes (WHO and Micheau). However, in adequate quality DNA samples (54 NPC cases), EBV-DNA was detected in 100% of cases using a nested-PCR, supporting the previous view that all histological types of NPC are in reality variants of EBV-infected neoplasia. ISH-negative cases probably reflect a lower sensitivity than PCR, particularly when a small number of viral copies are present, as well as a variable technical effectiveness for detected EBV, independent of the NPC histological type.