A photonic atom probe coupling 3D atomic scale analysis with in situ photoluminescence spectroscopy.

Laser enhanced field evaporation of surface atoms in laser-assisted Atom Probe Tomography (APT) can simultaneously excite photoluminescence in semiconductor or insulating specimens. An atom probe equipped with appropriate focalization and collection optics has been coupled with an in situ micro-photoluminescence (µPL) bench that can be operated during APT analysis. The photonic atom probe instrument we have developed operates at frequencies up to 500 kHz and is controlled by 150 fs laser pulses tunable in energy in a large spectral range (spanning from deep UV to near IR). Micro-PL spectroscopy is performed using a 320 mm focal length spectrometer equipped with a CCD camera for time-integrated and with a streak camera for time-resolved acquisitions. An example of application of this instrument on a multi-quantum well oxide heterostructure sample illustrates the potential of this new generation of tomographic atom probes.

Spatial and Compositional Biases Introduced by Position Sensitive Detection Systems in APT: A Simulation Approach.

Due to the low capacity of contemporary position-sensitive detectors in atom probe tomography (APT) to detect multiple events, material analyses that exhibit high numbers of multiple events are the most subject to compositional biases. To solve this limitation, some researchers have developed statistical correction algorithms. However, those algorithms are only efficient when one is confronted with homogeneous materials having nearly the same evaporation field between elements. Therefore, dealing with more complex materials must be accompanied by a better understanding of the signal loss mechanism during APT experiments. By modeling the evaporation mechanism and the whole APT detection system, it may be possible to predict compositional and spatial biases induced by the detection system. This paper introduces a systematic study of the impact of the APT detection system on material analysis through the development of a simulation tool.

Hypermethylation of the tumor suppressor gene PRDM1/Blimp-1 supports a pathogenetic role in EBV-positive Burkitt lymphoma.

PRDM1/Blimp-1 is a tumor suppressor gene in the activated B-cell subtype of diffuse large B-cell lymphomas. Its inactivation contributes to pathogenesis in this setting by impairing terminal B-cell differentiation induced by constitutive nuclear factor-κB activation. The role of PRDM1 in Burkitt lymphoma (BL) lymphomagenesis is not known. Here we identified hypermethylation of the promoter region and exon 1 of PRDM1 in all six Epstein-Barr virus (EBV)-positive BL cell lines and 12 of 23 (52%) primary EBV-positive BL or BL-related cases examined, but in none of the EBV-negative BL cell lines or primary tumors that we assessed, implying a tumor suppressor role for PRDM1 specifically in EBV-associated BL. A direct induction of PRDM1 hypermethylation by EBV is unlikely, as PRDM1 hypermethylation was not observed in EBV-immortalized B lymphoblastoid cell lines. Treatment of EBV-positive BL cells with 5' azacytidine resulted in PRDM1 induction associated with PRDM1 demethylation, consistent with transcriptional silencing of PRDM1 as a result of DNA methylation. Overexpression of PRDM1 in EBV-positive BL cell lines resulted in cell cycle arrest. Our results expand the spectrum of lymphoid malignancies in which PRDM1 may have a tumor suppressor role and identify an epigenetic event that likely contributes to the pathogenesis of BL.

Head and neck cancer. An aetiopathogenetic study of non-endemic lymphoepithelioma.

An aetiopathogenetic analysis of non-endemic nasopharyngeal carcinoma (NPC) in European and Southern American patient groups was performed. Specifically, the study sought to determine the proportion of Epstein-Barr Virus (EBV)-positive tumour cells in NPC patients in two very different populations (Europe and South America) in areas not associated with a high incidence of NPC. Clinical data (age, sex and onset of clinical disease) were also analyzed. A total of 50 NPC samples, 24 from a European hospital (EH) and 26 from two South American hospitals (SAH), were included. Nuclear staining for Epstein-Barr virus-encoded small RNA (EBER) was performed by in situ hybridization (ISH). Latent membrane protein 1 (LMP1) expression was measured by immunohistochemical (IHC) analysis. A higher incidence of NPC was observed in patients > 40 years of age in EH; in SAH, by contrast, the incidence was higher in patients aged ≤ 40 years. Cervical lymph node metastasis was detected in 31 patients (of whom 84.6% were from SAH). A total of 72% of samples were EBERpositive; the incidence of EBER positivity was greater in type 3 NPCs. EBV was detected in a large proportion of epithelial cells in samples from both EH and SAH (75% vs. 69.2%, respectively). An association was found between EBER detection in lymphocytes and patient origin (p = 0.0001). LMP1 expression was detected in 64% of patients. ISH for the detection of EBER is the most sensitive technique for demonstrating EBV in tumour tissue. The incidence of EBV was not significantly greater in either of the study populations, but was significantly higher in patients with type 3 NPC. Definitive histological diagnosis of NPC was reached earlier in EH than in SAH, where metastases were more frequently diagnosed, suggesting that the disease had reached a more advanced stage by the time treatment was started.

Polyclonal endemicity of Pseudomonas aeruginosa in a teaching hospital from Brazil: molecular typing of decade-old strains

Pseudomonas aeruginosa infections cause significant mortality and morbidity in health care settings. Strategies to prevent and control the emergence and spread of P. aeruginosa within hospitals involve implementation of barrier methods and antimicrobial stewardship programs. However, there is still much debate over which of these measures holds the utmost importance. Molecular strain typing may help elucidate this issue. In our study, 71 nosocomial isolates from 41 patients and 23 community-acquired isolates from 21 patients were genotyped. Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) was performed. Band patterns were compared using similarity coefficients of Dice, Jaccard and simple matching. Strain similarity for nosocomial strains varied from 0.14 to 1.00 (Dice); 0.08 to 1.00 (Jaccard) and 0.58 to 1.00 (simple matching). Forty patterns were identified. In most units, several clones coexisted. However, there was evidence of clonal dissemination in the high risk nursery, neurology and two surgical units. Each and every community-acquired strain produced a unique distinct pattern. Results suggest that cross transmission of P. aeruginosa was an uncommon event in our hospital. This points out to a minor role for barrier methods in the control of P. aeruginosa spread.

Expression profile of p63 in 127 patients with laryngeal squamous cell carcinoma.

OBJECTIVES: To evaluate p63 expression in laryngeal squamous cell carcinoma and its prognostic significance. METHODS: p63 expression was examined by immunohistochemistry and scored in 127 patients with laryngeal squamous cell carcinomas. RESULTS: Sixty-two cases had scored 3, sixty had scored 2, four had scored 1 and one case did not show any expression (48.8, 47.2, 3.1 and 0.8%, respectively). Overall survival was 73.9% at 24 months and 59.5% at 60 months. The disease-free survival was 77.2 and 75.1%, and the disease-specific survival was 79 and 67% at 24 and 60 months, respectively. Uni- and multivariate analysis identified that decreased immunoexpression of protein p63 was a statistically significant factor for the risk of recurrence and death by cancer. CONCLUSIONS: p63 expression was highly prevalent in laryngeal squamous cell carcinomas, and its underexpression was correlated with a worse prognosis.

Estrogen receptor-positive breast carcinomas in younger women are different from those of older women: a pathological and immunohistochemical study.

The higher frequency of triple-negative and HER-2-positive tumors detected in younger patients has been suggested as an explanation for the more aggressive tumor types observed in this age group. However, estrogen receptor (ER)-positive tumors are the most frequent subtype of breast carcinomas identified, even in younger patients. In this retrospective study, the morphological and immunohistochemical profiles of ER-positive breast carcinomas from women 35 yrs and younger that were diagnosed between 1997 and 2007 were evaluated. From these cases, 213 were selected based on the availability of pathology reports and paraffin blocks. For comparison, 117 consecutive cases of breast carcinomas diagnosed in patients >60 yrs from 2006 were included. Paraffin-embedded tumors were stained for expression of ER, progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), Ki-67 antigen, epidermal growth factor receptor (EGFR), cytokeratin 5/6, p53, vimentin, CD117, and p63 using tissue microarrays. ER-positive carcinomas were diagnosed in 120 (56.1%) samples of the younger patient group and in 92 (78.6%) samples of the older patient group. Of these ER-positive carcinomas, 48 (40%) from the younger patient group presented the subtype luminal A, compared with 53 (57.6%) from the older patient group (p=0.01). Tumors from the younger patient group were also associated with increased vascular involvement, co-expression of HER-2, and decreased expression of CD117. These results highlight differences in expression markers and the pathology of ER-positive tumors detected in younger women, with a notable characteristic being co-expression of HER-2.

Kaposi's sarcoma-associated herpesvirus infection and Kaposi's sarcoma in Brazil.

Kaposi's sarcoma (KS) became a critical health issue with the emergence of acquired immunodeficiency syndrome (AIDS) in the 1980s. Four clinical-epidemiological forms of KS have been described: classical KS, endemic KS, iatrogenic KS, and AIDS-associated KS. In 1994, Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus type 8 was identified by Chang and colleagues, and has been detected worldwide at frequencies ranging from 80 to 100%. The aim of the present study was to evaluate the frequency of KSHV infection in KS lesions from HIV-positive and HIV-negative patients in Brazil, as well as to review the current knowledge about KS transmission and detection. For these purposes, DNA from 51 cases of KS was assessed by PCR: 20 (39.2%) cases of classical KS, 29 (56.9%) of AIDS-associated KS and 2 (3.9%) of iatrogenic KS. Most patients were males (7.5:1, M/F), and mean age was 47.9 years (SD = +/- 18.7 years). As expected, HIV-positive KS patients were younger than patients with classical KS. On the other hand, patients with AIDS-associated KS have early lesions (patch and plaque) compared to classical KS patients (predominantly nodular lesions). This is assumed to be the result of the early diagnose of KS in the HIV-positive setting. KSHV infection was detected by PCR in almost all cases (48/51; 94.1%), irrespectively of the clinical-epidemiological form of KS. These results show that KSHV is associated with all forms of KS in Brazilian patients, a fact that supports the role of this virus in KS pathogenesis.

Kaposi's sarcoma-associated herpesvirus infection and Kaposi's sarcoma in Brazil

Kaposi's sarcoma (KS) became a critical health issue with the emergence of acquired immunodeficiency syndrome (AIDS) in the 1980s. Four clinical-epidemiological forms of KS have been described: classical KS, endemic KS, iatrogenic KS, and AIDS-associated KS. In 1994, Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus type 8 was identified by Chang and colleagues, and has been detected worldwide at frequencies ranging from 80 to 100 percent. The aim of the present study was to evaluate the frequency of KSHV infection in KS lesions from HIV-positive and HIV-negative patients in Brazil, as well as to review the current knowledge about KS transmission and detection. For these purposes, DNA from 51 cases of KS was assessed by PCR: 20 (39.2 percent) cases of classical KS, 29 (56.9 percent) of AIDS-associated KS and 2 (3.9 percent) of iatrogenic KS. Most patients were males (7.5:1, M/F), and mean age was 47.9 years (SD = ± 18.7 years). As expected, HIV-positive KS patients were younger than patients with classical KS. On the other hand, patients with AIDS-associated KS have early lesions (patch and plaque) compared to classical KS patients (predominantly nodular lesions). This is assumed to be the result of the early diagnose of KS in the HIV-positive setting. KSHV infection was detected by PCR in almost all cases (48/51; 94.1 percent), irrespectively of the clinical-epidemiological form of KS. These results show that KSHV is associated with all forms of KS in Brazilian patients, a fact that supports the role of this virus in KS pathogenesis.

Epstein-Barr virus infection and gastric carcinoma in São Paulo State, Brazil.

Epstein-Barr virus (EBV) is a ubiquitous herpesvirus, and most people have serological evidence of previous viral infection at adult age. EBV is associated with infectious mononucleosis and human cancers, including some lymphomas and gastric carcinomas. Although EBV was first reported in lymphoepithelioma-like gastric carcinoma, the virus was also found in conventional adenocarcinomas. In the present study, 53 gastric carcinomas diagnosed in São Paulo State, Brazil, were evaluated for EBV infection by non-isotopic in situ hybridization with a biotinylated probe (Biotin-AGACACCGTCCTCACCACCC GGGACTTGTA) directed to the viral transcript EBER-I, which is actively expressed in EBV latently infected cells. EBV infection was found in 6 of 53 (11.32%) gastric carcinomas, mostly from male patients (66.7%), with a mean age of 59 years old. Most EBV-positive tumors were in gastric antrum. Two EBV-positive tumors (33.3%) were conventional adenocarcinomas, whereas four (66.7%) were classified as lymphoepithelioma-like carcinomas. EBV infection in gastric carcinomas was reported elsewhere in frequencies that range from 5.6% (Korea) up to 18% (Germany). In Brazil, a previous work found EBV infection in 4 of 80 (5%) gastric carcinomas, whereas another study found 4.7 and 11.2% of EBV-positive gastric carcinomas of Brazilians of Japanese origin or not, respectively. In the present study, the frequency of EBV-positive gastric carcinomas is similar to that reported in other series, and the clinicopathologic characteristics of these EBV-positive tumors are in agreement with the data in the literature.

Epstein-Barr virus infection and gastric carcinoma in São Paulo State, Brazil

Epstein-Barr virus (EBV) is a ubiquitous herpesvirus, and most people have serological evidence of previous viral infection at adult age. EBV is associated with infectious mononucleosis and human cancers, including some lymphomas and gastric carcinomas. Although EBV was first reported in lymphoepithelioma-like gastric carcinoma, the virus was also found in conventional adenocarcinomas. In the present study, 53 gastric carcinomas diagnosed in São Paulo State, Brazil, were evaluated for EBV infection by non-isotopic in situ hybridization with a biotinylated probe (Biotin-AGACACCGTCCTCACCACCC GGGACTTGTA) directed to the viral transcript EBER-I, which is actively expressed in EBV latently infected cells. EBV infection was found in 6 of 53 (11.32 percent) gastric carcinomas, mostly from male patients (66.7 percent), with a mean age of 59 years old. Most EBV-positive tumors were in gastric antrum. Two EBV-positive tumors (33.3 percent) were conventional adenocarcinomas, whereas four (66.7 percent) were classified as lymphoepithelioma-like carcinomas. EBV infection in gastric carcinomas was reported elsewhere in frequencies that range from 5.6 percent (Korea) up to 18 percent (Germany). In Brazil, a previous work found EBV infection in 4 of 80 (5 percent) gastric carcinomas, whereas another study found 4.7 and 11.2 percent of EBV-positive gastric carcinomas of Brazilians of Japanese origin or not, respectively. In the present study, the frequency of EBV-positive gastric carcinomas is similar to that reported in other series, and the clinicopathologic characteristics of these EBV-positive tumors are in agreement with the data in the literature.

Polyamine metabolism in the Microsporidia.

Members of the phylum Microspora are all obligate intracellular parasites. Little is known concerning metabolic pathways in these parasites, some of which pose serious problems in immunocompromised patients. We investigated polyamine metabolism in the systemic pathogen Enterocytozoon cuniculi using intact pre-emergent spores, and cell-free preparations. We found both polyamine synthetic and interconversion pathways to be operative, as evidenced by conversion of ornithine into polyamines, and production of spermidine from spermine by pre-emergent spores. Recent developments in the antitumour field have highlighted the ability of bis-ethylated polyamine analogues to reduce polyamine levels and block growth of tumour cells. In light of enhanced polyamine uptake in Enc. cuniculi, we have begun to study bis-aryl 3-7-3 and bis-ethyl oligoamine analogues as leads for chemotherapy of microsporidia.

Polyamine metabolism as chemotherapeutic target in protozoan parasites.

Polyamines are essential cell constituents for all organisms. The present review highlights important differences in the synthesis, degradation, and interconversion of polyamines between the protozoan parasites (Trypanosoma brucei, Trypanosoma cruzi, Cryptosporidium parvum and Trichomonas vaginalis) and their mammalian hosts. Approaches include development of mono- and di-substituted polyamine analogs targeting polyamine interconversion, as well as more traditional targeting of synthetic enzymes and related pathways.

Trypanocidal activity of dicationic compounds related to pentamidine.

Eight dicationic compounds related to pentamidine were studied for trypanocidal activity in seven trypanosome isolates. In vitro studies revealed that diamidines are more potent than diimidazolines. For example, 2 (a diamidine) and 4 (a diimidazoline) inhibited the growth of KETRI 243 with IC50 values of 2.3 and 900 nM, respectively. Introduction of polar groups into the linker decreased the effectiveness of the compounds against drug-resistant trypanosomes. In compounds with a 2-butene linker between the cationic groups, trans-isomers were more potent than cis-isomers. The cis- and trans-buteneamidines cured infection caused by Trypanosoma brucei brucei (EATRO Lab 110) and protected mice against infection by Trypanosoma brucei rhodesiense isolates, some of which are resistant to diamidines and melarsoprol.

Abdominopelvic sarcoma of perivascular epithelioid cells. Report of four cases in young women, one with tuberous sclerosis.

The perivascular epithelioid cell has been proposed to be the unifying proliferating cell type in a number of lesions such as angiomyolipoma, lymphangiomyomatosis, clear cell "sugar" tumor and renal capsuloma. With the exception of rare examples of angiomyolipoma, they are non-metastasizing. We report four examples of a new member of this family of perivascular epithelioid cell neoplasms that occur in abdominopelvic location and show metastatic properties. The patients, all women, were aged 19 to 41 years (mean, 32), and presented with a tumor mass involving the serosa of the ileum, uterus or pelvic cavity. Morphologically, the tumors were composed of sheets of large polygonal cells with glycogen-rich clear or eosinophilic cytoplasm and moderately pleomorphic nuclei, traversed by a delicate vasculature, mimicking clear cell carcinoma. There were areas of coagulative necrosis and occasional mitotic figures. Intracytoplasmic brown pigment was present in two cases. Spindly cells, smooth muscle and fat were absent. Lymphovascular invasion was present in all, lymph node metastasis was documented in two and metastasis to the ovary was present in one case. Two patients developed widespread metastatic disease after 10 and 28 months from diagnosis. One patient showed the clinical signs of tuberous sclerosis. In spite of the epithelial-like appearance, the tumor cells were negative for epithelial markers but were strongly positive with the melanogenesis-related marker HMB45. Another melanogenesis marker (MART-1) was positive in two cases. Other markers including S-100 protein, vimentin, muscle-specific actin, desmin and chromogranin A were negative. Thus, these tumors are not readily classifiable in the existing schema of known entities, and show overlapping morpho-phenotypic features of clear cell "sugar" tumor of the lung and epithelioid angiomyolipoma. We consider them as sarcomas composed of a pure population of uncommitted perivascular epithelioid cell, that lack modulation toward smooth muscle or adipose cells.

Novel alkylpolyamine analogues that possess both antitrypanosomal and antimicrosporidial activity.

A novel series of alkyl- or aralkyl-substituted polyamine analogues was synthesized containing a 3-7-3 polyamine backbone. These analogues were evaluated in vitro, and in one case in vivo, for activity as antitrypanosomal agents, and for activity against opportunistic infection caused by Microsporidia. Compound 21 inhibits trypanosomal growth with an IC(50) as low as 31nM, while compound 24 shows promising activity in vitro against trypanosomes, and against Microsporidia in vitro and in vivo.

Polyamine synthesis and interconversion by the Microsporidian Encephalitozoon cuniculi.

Polyamines are small cationic molecules necessary for growth and differentiation in all cells. Although mammalian cells have been studied extensively, particularly as targets of polyamine antagonists, i.e. antitumor agents, polyamine metabolism has also been studied as a potential drug target in microorganisms. Since little is known concerning polyamine metabolism in the microsporidia, we investigated it in Encephalitozoon cuniculi, a microspordian associated with disseminated infections in humans. Organisms were grown in RK-13 cells and harvested using Percoll gradients. Electron microscopy indicated that the fractions banding at 1.051-1.059/g/ml in a microgradient procedure, and 1.102-1.119/g/ml in a scaled-up procedure were nearly homogenous, consisting of pre-emergent (immature) spores which showed large arrays of ribosomes near polar filament coils. Intact purified pre-emergent spores incubated with [1H] ornithine and methionine synthesized putrescine, spermidine, and spermine, while [14C]spermine was converted to spermidine and putrescine. Polyamine production from ornithine was inhibitable by DL-alpha-difluoromethylornithine (DFMO) but not by DL-alpha-difluoromethylarginine (DFMA). Cell-free extracts from mature spores released into the growth media had ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (AdoMetdc), and spermidine/spermine N1-acetyltransferase (SSAT) activities. ODC activity was inhibited by DFMO, but not by DFMA. AdoMetdc was putrescine-stimulated and inhibited by methylglyoxal-bis(guanylhydrazone); arginine decarboxylase activity could not be detected. It is apparent from these studies that Encephalitozoon cuniculi pre-emergent spores have a eukaryotic-type polyamine biosynthetic pathway and can interconvert exogenous polyamines. Pre-emergent spores were metabolically active with respect to polyamine synthesis and interconversion, while intact mature spores harvested from culture supernatants had little metabolic activity.

In situ kinetic characterization of methylthioadenosine transport by the adenosine transporter (P2) of the African Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense.

African trypanosomes are parasitic flagellates that live in the connective tissues of the host. Trypanosomes must obtain from their host adenine/adenosine and other nucleosides that can be salvaged through enzymatic cleavage. Methylthioadenosine (MTA) is a byproduct of polyamine metabolism, formed from the donation of an aminopropyl moiety by decarboxylated S-adenosylmethionine (dcAdoMet) to form spermidine. MTA is then cleaved phosphorolytically by MTA phosphorylase to methylthioribose-1-phosphate (MTR-1-P) and adenine. The uptake of MTA was compared with that of adenosine in two strains: Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense. The K(m) values for MTA and adenosine (with 5 mM inosine) transport by T. b. brucei were 1.4 and 0.175 mM, and the V(max) values were 70 and 7.8 micromol/L/min, respectively. The K(m) values for T. b. rhodesiense MTA and adenosine (with 5 mM inosine) transport were 1.2 and 0.11 mM, and the V(max) values were 52.6 and 2.9 micromol/L/min, respectively. Since MTA was not competitive with either AdoMet (100 microM), inosine (100 microM), or the methionine precursor ketomethylthiobutyrate (100 microM), it appears that MTA enters through the P(2) (adenosine/adenine) transport site. From this study and our previous work, we determined that these organisms transport adenylated intermediates of methionine metabolism found in sera for purine salvage and as an ancillary source of methionine. The significant ability of African trypanosomes to transport MTA and related intermediates is an important consideration in the design and development of selective chemotherapeutic agents.

Characterizing subpopulations of neoplastic cells in serous effusions. The role of immunocytochemistry.

OBJECTIVE: To analyze the role of immunochemistry in serous effusions. STUDY DESIGN: We analyzed cell blocks of 18 pleural and 18 peritoneal effusions diagnosed as malignant (18), benign (14) and suspicious (4). They were immunostained by the avidin-biotin complex method with a panel of four monoclonal antibodies--CEA, Ber-EP4, LeuM1 (CD15) and p53--and, for lectins (Ulex europaeus) UEA-l, ConA and ConBr. RESULTS: Seventeen of the 18 cases of adenocarcinoma were positive for CEA (95%), 12 (66.6%) for Ber-EP4, 11 (61%) for CD15 and 11 (61%) for p53. Twelve of the 18 (66.6%) were positive for UEA-1, CEA, Ber-EP4 and CD15. UEA-1 did not react with mesothelial cells. p53 Gave a positive reaction in only one case, reactive mesothelial cells. ConA and ConBr reacted indiscriminately with benign and malignant cells; thus, it was not useful in distinguishing between these cells. CONCLUSION: In this context no antibody used alone is reliable for corroborating a diagnosis, but the selective use of a small panel of three markers (CEA, Ber-EP4 and LeuM1) can be very useful in solving diagnostic difficulties in the cytodiagnosis of serous effusions.