Translational activation by a synthetic PPR protein elucidates control of psbA translation in Arabidopsis chloroplasts.

Translation initiation on chloroplast psbA mRNA in plants scales with light intensity, providing its gene product, D1, as needed to replace photodamaged D1 in Photosystem II. The psbA translational activator HIGH CHLOROPHYLL FLUORESCENCE 173 (HCF173) has been hypothesized to mediate this regulation. HCF173 belongs to the short-chain dehydrogenase/reductase superfamily, associates with the psbA 5'-untranslated region (5'-UTR), and has been hypothesized to enhance translation by binding an RNA segment that would otherwise pair with and mask the ribosome binding region. To test these hypotheses, we examined whether a synthetic pentatricopeptide repeat (sPPR) protein can substitute for HCF173 when bound to the HCF173 binding site. We show that an sPPR designed to bind HCF173's footprint in the psbA 5'-UTR bound the intended site in vivo and partially substituted for HCF173 to activate psbA translation. However, sPPR-activated translation did not respond to light. These results imply that HCF173 activates translation, at least in part, by sequestering the RNA it binds to maintain an accessible ribosome binding region, and that HCF173 is also required to regulate psbA translation in response to light. Translational activation can be added to the functions that can be programmed with sPPR proteins for synthetic biology applications in chloroplasts.

Chilean consensus by expert panel using the Delphi technique for primary and secondary prevention of gastric cancer. / Estrategias para la prevención primaria y secundaria del cáncer gástrico: consenso chileno de panel de expertos con técnica Delfi.

INTRODUCTION: Gastric cancer (GC) is the first cause of cancer-related death in Chile and 6th in Latin America and the Caribbean (LAC). Helicobacter pylori (H. pylori) is the main gastric carcinogen, and its treatment reduces GC incidence and mortality. Esophageal-gastro-duodenoscopy (EGD) allows for the detection of premalignant conditions and early-stage GC. Mass screening programs for H. pylori infection and screening for premalignant conditions and early-stage GC are not currently implemented in LAC. The aim of this study is to establish recommendations for primary and secondary prevention of GC in asymptomatic standard-risk populations in Chile. METHODS: Two on-line synchronous workshops and a seminar were conducted with Chilean experts. A Delphi panel consensus was conducted over 2 rounds to achieve>80% agreement on proposed primary and secondary prevention strategies for the population stratified by age groups. RESULTS: 10, 12, and 12 experts participated in two workshops and a seminar, respectively. In the Delphi panel, 25 out of 37 experts (77.14%) and 28 out of 52 experts (53.85%) responded. For the population aged 16-34, there was no consensus on non-invasive testing and treatment for H. pylori, and the use of EGD was excluded. For the 35-44 age group, non-invasive testing and treatment for H. pylori is recommended, followed by subsequent test-of-cure using non-invasive tests (stool antigen test or urea breath test). In the ≥45 age group, a combined strategy is recommended, involving H. pylori testing and treatment plus non-invasive biomarkers (H. pylori IgG serology and serum pepsinogens I and II); subsequently, a selected group of subjects will undergo EGD with gastric biopsies (Sydney Protocol), which will be used to stratify surveillance according to the classification Operative Link for Gastritis Assessment (OLGA); every 3 years for OLGA III-IV and every 5 years for OLGA I-II. CONCLUSION: A "test-and-treat" strategy for H. pylori infection based on non-invasive studies (primary prevention) is proposed in the 35-44 age group, and a combined strategy (serology and EGD) is recommended for the ≥45 age group (primary and secondary prevention). These strategies are potentially applicable to other countries in LAC.

In vivo stabilization of endogenous chloroplast RNAs by customized artificial pentatricopeptide repeat proteins.

Pentatricopeptide repeat (PPR) proteins are helical repeat-proteins that bind RNA in a modular fashion with a sequence-specificity that can be manipulated by the use of an amino acid code. As such, PPR repeats are promising scaffolds for the design of RNA binding proteins for synthetic biology applications. However, the in vivo functional capabilities of artificial PPR proteins built from consensus PPR motifs are just starting to be explored. Here, we report in vivo functions of an artificial PPR protein, dPPRrbcL, made of consensus PPR motifs that were designed to bind a sequence near the 5' end of rbcL transcripts in Arabidopsis chloroplasts. We used a functional complementation assay to demonstrate that this protein bound its intended RNA target with specificity in vivo and that it substituted for a natural PPR protein by stabilizing processed rbcL mRNA. We targeted a second protein of analogous design to the petL 5' UTR, where it substituted for the native stabilizing PPR protein PGR3, albeit inefficiently. These results showed that artificial PPR proteins can be engineered to functionally mimic the class of native PPR proteins that serve as physical barriers against exoribonucleases.

CFM1, a member of the CRM-domain protein family, functions in chloroplast group II intron splicing in Setaria viridis.

The chloroplast RNA splicing and ribosome maturation (CRM) domain is a RNA-binding domain found in a plant-specific protein family whose characterized members play essential roles in splicing group I and group II introns in mitochondria and chloroplasts. Together, these proteins are required for splicing of the majority of the approximately 20 chloroplast introns in land plants. Here, we provide evidence from Setaria viridis and maize that an uncharacterized member of this family, CRM Family Member1 (CFM1), promotes the splicing of most of the introns that had not previously been shown to require a CRM domain protein. A Setaria mutant expressing mutated CFM1 was strongly disrupted in the splicing of three chloroplast tRNAs: trnI, trnV and trnA. Analyses by RNA gel blot and polysome association suggest that the tRNA deficiencies lead to compromised chloroplast protein synthesis and the observed whole-plant chlorotic phenotypes. Co-immunoprecipitation data demonstrate that the maize CFM1 ortholog is bound to introns whose splicing is disrupted in the cfm1 mutant. With these results, CRM domain proteins have been shown to promote the splicing of all but two of the introns found in angiosperm chloroplast genomes.

Engineered PPR proteins as inducible switches to activate the expression of chloroplast transgenes.

The engineering of plant genomes presents exciting opportunities to modify agronomic traits and to produce high-value products in plants. Expression of foreign proteins from transgenes in the chloroplast genome offers advantages that include the capacity for prodigious protein output, the lack of transgene silencing and the ability to express multicomponent pathways from polycistronic mRNA. However, there remains a need for robust methods to regulate plastid transgene expression. We designed orthogonal activators that boost the expression of chloroplast transgenes harbouring cognate cis-elements. Our system exploits the programmable RNA sequence specificity of pentatricopeptide repeat proteins and their native functions as activators of chloroplast gene expression. When expressed from nuclear transgenes, the engineered proteins stimulate the expression of plastid transgenes by up to ~40-fold, with maximal protein abundance approaching that of Rubisco. This strategy provides a means to regulate and optimize the expression of foreign genes in chloroplasts and to avoid deleterious effects of their products on plant growth.

The Arabidopsis pentatricopeptide repeat protein LPE1 and its maize ortholog are required for translation of the chloroplast psbJ RNA.

The expression of chloroplast genes relies on a host of nucleus-encoded proteins. Identification of such proteins and elucidation of their functions are ongoing challenges. We used ribosome profiling to revisit the function of the pentatricopeptide repeat protein LPE1, reported to stimulate translation of the chloroplast psbA mRNA in Arabidopsis. Mutation of the maize LPE1 ortholog causes a photosystem II (PSII) deficiency and a defect in translation of the chloroplast psbJ open reading frame (ORF) but has no effect on psbA expression. To reflect this function, we named the maize LPE1 ortholog Translation of psbJ 1 (TPJ1). Arabidopsis lpe1 mutants likewise exhibit a loss of psbJ translation, and have, in addition, a decrease in psbN translation. We detected a small decrease in ribosome occupancy on the psbA mRNA in Arabidopsis lpe1 mutants, but ribosome profiling analyses of other PSII mutants (hcf107 and hcf173) in conjunction with in vitro RNA binding data strongly suggest that this is a secondary effect of their PSII deficiency. We conclude that maize TPJ1 promotes PSII synthesis by activating translation of the psbJ ORF, that this function is conserved in Arabidopsis LPE1, and that an additional role for LPE1 in psbN translation contributes to the PSII deficiency in lpe1 mutants.

Unexpected functional versatility of the pentatricopeptide repeat proteins PGR3, PPR5 and PPR10.

Pentatricopeptide repeat (PPR) proteins are a large family of helical repeat proteins that bind RNA in mitochondria and chloroplasts. Sites of PPR action have been inferred primarily from genetic data, which have led to the view that most PPR proteins act at a very small number of sites in vivo. Here, we report new functions for three chloroplast PPR proteins that had already been studied in depth. Maize PPR5, previously shown to promote trnG splicing, is also required for rpl16 splicing. Maize PPR10, previously shown to bind the atpI-atpH and psaJ-rpl33 intercistronic regions, also stabilizes a 3'-end downstream from psaI. Arabidopsis PGR3, shown previously to bind upstream of petL, also binds the rpl14-rps8 intercistronic region where it stabilizes a 3'-end and stimulates rps8 translation. These functions of PGR3 are conserved in maize. The discovery of new functions for three proteins that were already among the best characterized members of the PPR family implies that functional repertoires of PPR proteins are more complex than have been appreciated. The diversity of sequences bound by PPR10 and PGR3 in vivo highlights challenges of predicting binding sites of native PPR proteins based on the amino acid code for nucleotide recognition by PPR motifs.

RNA-binding specificity landscape of the pentatricopeptide repeat protein PPR10.

Pentatricopeptide repeat (PPR) proteins comprise a large family of helical repeat proteins that influence gene expression in mitochondria and chloroplasts. PPR tracts can bind RNA via a modular one repeat-one nucleotide mechanism in which the nucleotide is specified by the identities of several amino acids in each repeat. This mode of recognition, the so-called PPR code, offers opportunities for the prediction of native PPR binding sites and the design of proteins to bind specified RNAs. However, a deep understanding of the parameters that dictate the affinity and specificity of PPR-RNA interactions is necessary to realize these goals. We report a comprehensive analysis of the sequence specificity of PPR10, a protein that binds similar RNA sequences of ∼18 nucleotides (nt) near the chloroplast atpH and psaJ genes in maize. We assessed the contribution of each nucleotide in the atpH binding site to PPR10 affinity in vitro by analyzing the effects of single-nucleotide changes at each position. In a complementary approach, the RNAs bound by PPR10 from partially randomized RNA pools were analyzed by deep sequencing. The results revealed three patches in which nucleotide identity has a major impact on binding affinity. These include 5 nt for which protein contacts were not observed in a PPR10-RNA crystal structure and 4 nt that are not explained by current views of the PPR code. These findings highlight aspects of PPR-RNA interactions that pose challenges for binding site prediction and design.

A combinatorial amino acid code for RNA recognition by pentatricopeptide repeat proteins.

The pentatricopeptide repeat (PPR) is a helical repeat motif found in an exceptionally large family of RNA-binding proteins that functions in mitochondrial and chloroplast gene expression. PPR proteins harbor between 2 and 30 repeats and typically bind single-stranded RNA in a sequence-specific fashion. However, the basis for sequence-specific RNA recognition by PPR tracts has been unknown. We used computational methods to infer a code for nucleotide recognition involving two amino acids in each repeat, and we validated this model by recoding a PPR protein to bind novel RNA sequences in vitro. Our results show that PPR tracts bind RNA via a modular recognition mechanism that differs from previously described RNA-protein recognition modes and that underpins a natural library of specific protein/RNA partners of unprecedented size and diversity. These findings provide a significant step toward the prediction of native binding sites of the enormous number of PPR proteins found in nature. Furthermore, the extraordinary evolutionary plasticity of the PPR family suggests that the PPR scaffold will be particularly amenable to redesign for new sequence specificities and functions.

Protein-mediated protection as the predominant mechanism for defining processed mRNA termini in land plant chloroplasts.

Most chloroplast mRNAs are processed from larger precursors. Several mechanisms have been proposed to mediate these processing events, including site-specific cleavage and the stalling of exonucleases by RNA structures. A protein barrier mechanism was proposed based on analysis of the pentatricopeptide repeat (PPR) protein PPR10: PPR10 binds two intercistronic regions and impedes 5'- and 3'-exonucleases, resulting in processed RNAs with PPR10 bound at the 5'- or 3'-end. In this study, we provide evidence that protein barriers are the predominant means for defining processed mRNA termini in chloroplasts. First, we map additional RNA termini whose arrangement suggests biogenesis via a PPR10-like mechanism. Second, we show that the PPR protein HCF152 binds to the immediate 5'- or 3'-termini of transcripts that require HCF152 for their accumulation, providing evidence that HCF152 defines RNA termini by blocking exonucleases. Finally, we build on the observation that the PPR10 and HCF152 binding sites accumulate as small chloroplast RNAs to infer binding sites of other PPR proteins. We show that most processed mRNA termini are represented by small RNAs whose sequences are highly conserved. We suggest that each such small RNA is the footprint of a PPR-like protein that protects the adjacent RNA from degradation.

APO1 promotes the splicing of chloroplast group II introns and harbors a plant-specific zinc-dependent RNA binding domain.

Arabidopsis thaliana APO1 is required for the accumulation of the chloroplast photosystem I and NADH dehydrogenase complexes and had been proposed to facilitate the incorporation of [4Fe-4S] clusters into these complexes. The identification of maize (Zea mays) APO1 in coimmunoprecipitates with a protein involved in chloroplast RNA splicing prompted us to investigate a role for APO1 in splicing. We show here that APO1 promotes the splicing of several chloroplast group II introns: in Arabidopsis apo1 mutants, ycf3-intron 2 remains completely unspliced, petD intron splicing is strongly reduced, and the splicing of several other introns is compromised. These splicing defects can account for the loss of photosynthetic complexes in apo1 mutants. Recombinant APO1 from both maize and Arabidopsis binds RNA with high affinity in vitro, demonstrating that DUF794, the domain of unknown function that makes up almost the entirety of APO1, is an RNA binding domain. We provide evidence that DUF794 harbors two motifs that resemble zinc fingers, that these bind zinc, and that they are essential for APO1 function. DUF794 is found in a plant-specific protein family whose members are all predicted to localize to mitochondria or chloroplasts. Thus, DUF794 adds a new example to the repertoire of plant-specific RNA binding domains that emerged as a product of nuclear-organellar coevolution.

Mechanism of RNA stabilization and translational activation by a pentatricopeptide repeat protein.

Pentatricopeptide repeat (PPR) proteins comprise a large family of helical repeat proteins that bind RNA and modulate organellar RNA metabolism. The mechanisms underlying the functions attributed to PPR proteins are unknown. We describe in vitro studies of the maize protein PPR10 that clarify how PPR10 modulates the stability and translation of specific chloroplast mRNAs. We show that recombinant PPR10 bound to its native binding site in the chloroplast atpI-atpH intergenic region (i) blocks both 5'→3' and 3'→ 5 exoribonucleases in vitro; (ii) is sufficient to define the native processed atpH mRNA 5'-terminus in conjunction with a generic 5'→3' exoribonuclease; and (iii) remodels the structure of the atpH ribosome-binding site in a manner that can account for PPR10's ability to enhance atpH translation. In addition, we show that the minimal PPR10-binding site spans 17 nt. We propose that the site-specific barrier and RNA remodeling activities of PPR10 are a consequence of its unusually long, high-affinity interface with single-stranded RNA, that this interface provides a functional mimic to bacterial small RNAs, and that analogous activities underlie many of the biological functions that have been attributed to PPR proteins.

The critical DNA damage by benzo(a)pyrene in lung tissues of smokers and approaches to preventing its formation.

Benzo(a)pyrene (BP) and cadmium are environmental pollutants found in foodstuffs, cigarette smoke, and polluted air. BP is converted in liver and lung to benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE) by the enzymes of the cytochrome P450 (CYP) superfamily, namely CYP1A1/1A2, and CYP1B1. BPDE reacts with DNA primarily at the N(2)-position of guanine, producing benzo(a)pyrene-7,8-diol-9,10-epoxide-N(2)-deoxyguanosine (BPDE-dG) adduct. BPDE reacts with DNA also at N(6) position of adenine, producing the minor N(6)-deoxyadenosine adduct, but BPDE-dG adduct is a well-established risk factor for lung cancer. We thus argue that BPDE-dG adduct could be used as a model biomarker in searching and validating of approaches to reducing lung cancer risk. If the formation of BPDE-dG adduct were to be inhibited or blocked in bronchial epithelial cells, so could lung cancer development. The best way to lower BPDE-dG formation in the lung is to stop smoking. However, the following approaches could also be considered for highly addicted smokers: (a) decrease BP and cadmium intake from food, cigarettes and other environmental sources; (b) avoid meat and other food high in BP and cadmium; (c) decrease the CYP-mediated conversion of BP in liver and lung; (d) lower free radicals and cadmium in cigarette smoke; and (e) increase BPDE detoxification.

DNA damage by benzo(a)pyrene in human cells is increased by cigarette smoke and decreased by a filter containing rosemary extract, which lowers free radicals.

We found previously that the human lung benzo(a)pyrene (BP)-7,8-diol-9,10-epoxide-N(2)-deoxyguanosine (BPDE-dG) adduct concentrate in the target bronchial cells. This adduct is now considered to be critical event in tumorigenesis by BP. In this study, we investigate the contribution of cigarette smoke on the BPDE-dG formation. In a cell-free system, the amount of (-)-anti-BPDE-dG adduct increased linearly with concentration of cigarette smoke in the presence of (+)-BP-7,8-diol. Catalase and superoxide dismutase inhibited its formation by >80%. When MCF-7 cells were treated for 2 hours with the (+)-BP-7,8-diol, cigarette smoke increased dose dependently the formation of (-)-anti-BPDE-dG and decreased the cytochrome P450 (CYP)-dependent formation of (+)-r-7,t-8-dihydroxy-c-9,10-oxy-7,8,9,10-tetrahydro-BP the adduct. Then, cells were treated for up to 1 day with BP and then exposed for 2 hours with cigarette smoke. During these 2 hours, there are twice the increase in the adduct formation in cells treated with cigarette smoke compared with levels in nontreated cells due to CYP activity. Thus, cigarette smoke containing reactive oxygen species may activate the second step of BP metabolic way, leading to the formation of BPDE-dG adduct. Cigarette smoke thus seems may be in part responsible for the formation of the critical lung tumorigenic adduct. Finally, modified cigarette filter containing rosemary extract decreases by >70% of the BPDE-dG adducts level due to the cigarette smoke in MCF-7 cells. This approach may lead to decreasing lung cancer risk in addicted smokers.

Formation of the CRS2-CAF2 group II intron splicing complex is mediated by a 22-amino acid motif in the COOH-terminal region of CAF2.

CRS2-associated factors 1 and 2 (CAF1 and CAF2) are closely related proteins that function in concert with chloroplast RNA splicing 2 (CRS2) to promote the splicing of specific sets of group II introns in maize chloroplasts. The CRS2-CAF complexes bind tightly to their cognate group II introns in vivo, with the CAF subunit determining the intron specificity of the complex. In this work we show that the CRS2-CAF complexes are stable in the absence of their intron targets and that CRS2 binds a 22 amino acid motif in the COOH-terminal region of CAF2 that is conserved in CAF1. Yeast two-hybrid assays and co-fractionation studies using recombinant proteins show that this motif is both necessary and sufficient to bind CRS2. The 22-amino acid motif is predicted to form an amphipathic helix whose hydrophobic surface is conserved between CAF1 and CAF2. We propose that this surface binds the hydrophobic patch on the surface of CRS2 previously shown to be necessary for the interaction between CRS2 and CAF2.

Presencia de microorganismos productores de b-lactamasa en dientes de pacientes con periodontitis apical crónica supurativa / Presence of microorganisms producing b-lactamases in teeth of patients with suppurative chronic apical periodontitis

Este artículo une los resultados de trabajos de grado realizados en el 2002 y en 2004 que tienen como propósito determinar la presencia de microorganismos productores de b-lactamasas en dientes con periodontitis apical crónica supurativa. La segunda parte se encaminó a obtener una ampliación de la muestra obtenida en la primera etapa del presente estudio y poder evaluar los resultados con un muestreo más representativo. Se tomaron 39 muestras de conductos con diangóstico de periodontitis apical crónica supurativa en el Hospital Rafael Uribe Uribe, que posteriormente fueron llevados al laboratorio de la Universidad El Bosque, en un medio de transporte VMGAIII. Se identificaron los bacilos gram negativos potencialmente productores de b-lactamasas mediante el sistema Rapid ID32A(R)(Biomerieux), a los que se les reálizó prueba de b-lactamasa Cefinase(R)(Becton Dickinson). De un total de 39 muestras, 14 no se tomaron en cuenta por resultar negativas (ausencia de microorganismos); en las 25 restantes se aisló: Prevotella denticola, Porphyromonas gingivalis, Porphyromonas asacharolitica, Actinomyces Spp., Prevotella intermedia/nigrecens, Propionibacterium acnes, A. meyeri, Fusobacterium Spp., A. odontoliticus, Prevotella melaninogenica, Peptostreptococcus magnus, Campylobacter Spp., Peptoestreptococcus micros, Peptoestreptococcus anaerobios, Serratia Marscenscens, Eubacterium Spp., y Staphilococcus Spp. Se encontró producción de b-lactamasa en Pophyromonas asacharolitica (1/1), Prevotella denticola (1/1), Prevotella intermedia (3/3), Prevotella melaninogenica (1/1), Prevotella intermedia/nigrecens (3/5), Serratia Marscenscens (1/1). Con los resultados obtenidos se sugiere determinar en una próxima investigación si estos microorganismos intervienen en los procesos de agudización de la periodontitis apical crónica supurativa y posteriormente determinar una adecuada terapia antibiótica

High DNA damage by benzo[a]pyrene 7,8-diol-9,10-epoxide in bronchial epithelial cells from patients with lung cancer: comparison with lung parenchyma.

In the present study, the level of benzo[a]pyrene 7,8-diol-9,10-epoxide-N(2)-deoxyguanosine (BPDE-N(2)-dG) in normal bronchial epithelial cells from non-cancerous bronchus of 22 lung cancer subjects was evaluated and compared to the lung parenchyma. We found very high formation of BPDE-N(2)-dG adduct in samples corresponding to a pure preparation of bronchial epithelial cells with 4-fold interindividual differences in the DNA adduct levels in the range of 36.5-175.4 BPDE-N(2)-dG adducts/10(8) nucleotides in smokers (mean: 84.7+/-38.4; n = 13) and 3-fold differences in the range of 19.7-62.4 in non-smokers (mean: 37.6+/-22.2; n = 3). DNA isolated from the bronchial tissue consisting of bronchial lining epithelium with adjacent lamina propria showed significantly lower BPDE-N(2)-dG formation (P < 0.001) in the range of 0.4-4.2 BPDE-N(2)-dG adducts/10(8) nucleotides (mean: 1.8+/-0.56; n = 6). This difference is clearly related to the procedure used to prepare the bronchial tissue samples leading to the presence of different types of cells. Eight samples from the normal parenchyma did not show measurable adducts, the other 14 samples showed 50-fold variation (mean: 1.7+/-1.5; range 0.1-5.2 adducts/10(8) nucleotides; n = 14). There were considerably higher adduct levels in pure bronchial epithelial cells than in parenchymal tissue (75.8+/-38.8 vs 0.9+/-1.5 adducts/10(8) nucleotides) (P < 0.0002) BPDE-N(2)-dG adduct concentrate almost exclusively in bronchial epithelial cells. The adduct values obtained in bronchial epithelial cells could be considered as 'critical' for the initiation of human lung cancer. The high formation of BPDE-N(2)-dG adducts in bronchial epithelial cells and investigations showing that the profile of mutations induced by BPDE in these cells is similar to that seen in the p53 gene isolated from human lung tumors implicates benzo[a]pyrene as important carcinogen in tobacco-induced lung cancer in human beings.

Spirometric function in children of Mexico City compared to Mexican-American children.

We set out to describe the pattern of lung function growth in Mexican students from 8-20 years of age, using internationally accepted equipment and methodology, and to compare it to values reported for Mexican-American children. Out of a total of 6,803 students from primary school to high school studied cross-sectionally in the Mexico City metropolitan area, we selected 4,009 asymptomatic, nonobese, nonsmoker subjects to generate spirometric prediction equations. We describe regression equations for the main spirometric variables (log transformed) based on age, height, and weight, and separated for males and females. Spirometric function in the population studied was above that predicted for European (Quanjer et al. [1987] Pediatr Pulmonol 19:135-142) or Mexican-American children, for the same age, height, and gender. On average, forced expiratory volume in 1 sec (FEV(1)) in Mexican children was 9.5% above that of Europeans (Quanjer et al. [1987] Pediatr Pulmonol 19:135-142), 14% and 5% above Hispanics reported by (Coultas et al. [1988] Am Rev Respir Dis 138:1386-1392) and (Hsu et al. [1979] J Pediatr 95:14-23), respectively, and 5% above Mexican-Americans from the third National Health and Nutrition Examination Survey study. Similarly, FVC was 8%, 14%, 8%, and 5.6% above the figures predicted by the same authors. The largest errors of prediction of foreign equations occurred in extremely tall or short subjects, and therefore a single proportional adjustment is unfeasible.

CYP1A1 and GSTM1 genotypes affect benzo[a]pyrene DNA adducts in smokers' lung: comparison with aromatic/hydrophobic adduct formation.

Benzo[a]pyrene diol epoxide (BPDE)-DNA adducts are involved in the induction of p53 mutations and probably in the causation of human lung cancer associated with cigarette smoking. The ratio between CYP1A1 and GST enzyme activities is a critical determinant of the target dose of carcinogenic BPDE and other DNA-reactive PAH metabolites. In this review, we summarize the published data on modulation of (+)-anti-BPDE-DNA adduct levels in smokers' lungs by CYP1A1*2 genotypes alone or in combination with GSTM1 polymorphism and compare these results with those reported for aromatic/hydrophobic (bulky) DNA adducts. The data published so far show only a trend for a non-significant increase in bulky DNA adduct levels in subjects with GSTM1*0 or the CYP1A1*2-GSTM1*0 genotype combination. In contrast, a clear dependence of (+)-anti-BPDE-DNA adduct levels was found as a function of the CYP1A1 and GSTM1 genotypes: In lung parenchyma, this adduct was more pronounced in persons with the GSTM1*0 genotype, and CYP1A1*2-GSTM1*0 carriers had higher (+)-anti-BPDE-DNA adduct levels than those with CYP1A1*1/*1-GSTM1*0. The homozygous CYP1A1*2/*2 carriers in the GSTM1*0 group had the highest (+)-anti-BPDE-DNA adduct levels. Our analysis leads to the conclusion that the risk-modifying effects of metabolic genotypes and of gene interactions might be more easily identifiable if specific markers of structurally defined adducts were used, such as the (+)-anti-BPDE-DNA adduct. These results are also consistent with the hypothesis that BP (PAH) induce G:C to T:A transversion mutations in the hotspot codons of the p53 tumor suppressor gene and are thus involved in malignant transformation of the lung tissue of smokers.

Macroglobulinemia de Waldenstron / Waldestrom's macroglobulinemia

Se presenta el caso clínico de un hombre de 70 años que consultó luego de varios meses de mareos, cansancio muscular, baja de peso y palidez. El estudio realizado demostró: pancitopenia con anemia normocítica, normocrómica, arregenerativa; hiperproteínemia con un componente monoclonal; gammapatía monoclonal IgM kappa con cadena liviana lambda libre; ausencia de lesiones osteolíticas; médula ósea con infiltración linfomatosa y disminución de las series eritroide, mieloide y megacariocítica pero sólo con 3 por ciento de plasmocitos; hiperviscosidad sanguínea. Luego de dos ciclos de melfalan y prednisona el paciente reingresa con un síndrome febril y compromiso de conciencia y fallece a los pocas horas con una sepsis a gram negativos (Escherichia coli) y una infección meníngea