Spectral hole burning: examples from photosynthesis

The optical spectra of photosynthetic pigment–protein complexes usually show broad absorption bands, often consisting of a number of overlapping, ‘hidden’ bands belonging to different species. Spectral hole burning is an ideal technique to unravel the optical and dynamic properties of such hidden species. Here, the principles of spectral hole burning (HB) and the experimental set-up used in its continuous wave (CW) and time-resolved versions are described. Examples from photosynthesis studied with hole burning, obtained in our laboratory, are then presented. These examples have been classified into three groups according to the parameters that were measured: (1) hole widths as a function of temperature, (2) hole widths as a function of delay time and (3) hole depths as a function of wavelength. Two examples from light-harvesting (LH) 2 complexes of purple bacteria are given within the first group: (a) the determination of energy-transfer times from the chromophores in the B800 ring to the B850 ring, and (b) optical dephasing in the B850 absorption band. One example from photosystem II (PSII) sub-core complexes of higher plants is given within the second group: it shows that the size of the complex determines the amount of spectral diffusion measured. Within the third group, two examples from (green) plants and purple bacteria have been chosen for: (a) the identification of ‘traps’ for energy transfer in PSII sub-core complexes of green plants, and (b) the uncovering of the lowest k = 0 exciton-state distribution within the B850 band of LH2 complexes of purple bacteria. The results prove the potential of spectral hole burning measurements for getting quantitative insight into dynamic processes in photosynthetic systems at low temperature, in particular, when individual bands are hidden within broad absorption bands. Because of its high-resolution wavelength selectivity, HB is a technique that is complementary to ultrafast pump–probe methods. In this review, we have provided an extensive bibliography for the benefit of scientists who plan to make use of this valuable technique in their future research

The Minimal Proteome in the Reduced Mitochondrion of the Parasitic Protist Giardia intestinalis

The mitosomes of Giardia intestinalis are thought to be mitochondria highly-reduced in response to the oxygen-poor niche. We performed a quantitative proteomic assessment of Giardia mitosomes to increase understanding of the function and evolutionary origin of these enigmatic organelles. Mitosome-enriched fractions were obtained from cell homogenate using Optiprep gradient centrifugation. To distinguish mitosomal proteins from contamination, we used a quantitative shot-gun strategy based on isobaric tagging of peptides with iTRAQ and tandem mass spectrometry. Altogether, 638 proteins were identified in mitosome-enriched fractions. Of these, 139 proteins had iTRAQ ratio similar to that of the six known mitosomal markers. Proteins were selected for expression in Giardia to verify their cellular localizations and the mitosomal localization of 20 proteins was confirmed. These proteins include nine components of the FeS cluster assembly machinery, a novel diflavo-protein with NADPH reductase activity, a novel VAMP-associated protein, and a key component of the outer membrane protein translocase. None of the novel mitosomal proteins was predicted by previous genome analyses. The small proteome of the Giardia mitosome reflects the reduction in mitochondrial metabolism, which is limited to the FeS cluster assembly pathway, and a simplicity in the protein import pathway required for organelle biogenesis

Catecholamine-Synthesizing Enzymes Are Expressed in Parasympathetic Head and Neck Paraganglioma Tissue

Background/Aim: Increased dopamine production may be a feature of head and neck paraganglioma (HNPGL). F-18-fluorodihydroxyphenylalanine positron emission tomography scintigraphy has a high sensitivity for detecting HNPGLs. These observations strongly suggest that HNPGLs have the capacity for L-3,4-dihydroxyphenylalanine uptake and conversion towards dopamine. Therefore, our aim was to demonstrate the presence of catecholamine-synthesizing enzymes, i.e. tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC) and dopamine beta-hydroxylase (DBH) in HNPGL tissue. Methods: A single-center study was performed among patients who underwent surgery for HNPGL at a single university referral center between 1994 and 2012. HNPGL tissue was immunohistochemically stained for TH, AADC and DBH. Data on paraganglioma-associated germline mutations, preoperative biochemical phenotype and imaging studies were retrieved. Catecholamine excess was defined as preoperative plasma and/or urinary levels of metanephrine, normetanephrine or 3-methoxytyramine above the upper reference limit. Results: Nineteen HNPGLs from 18 patients were evaluated. All tumor tissues (100%) stained positive for AADC, 6 (32%) for TH and 2 (11%) for DBH. Of 3 HNPGLs staining positive for DBH, 2 were also positive for AADC and TH. Catecholamine excess was only present in 1 patient (5%). The HNPGLs of this single patient only showed positive staining for AADC. Conclusions: Catecholamine-synthesizing enzymes, in particular AADC, are expressed in the majority of HNPGL tissues. (C) 2015 S. Karger AG, Base

Osteoporosis in psoriatic arthritis: is there any?

AIMS: Although considered as a feature of inflammatory rheumatic diseases, there is a lot of controversy around low bone mass in patients with psoriatic arthritis. The aim of this cross-sectional study was to analyze bone mineral density in patients with psoriatic arthritis, as well as to investigate its possible association with some measures of disease activity and functional capacity. ----- SUBJECTS AND METHODS: Sixty-nine patients with established psoriatic arthritis (mean age 56.20 ± 12.23 years) and who have not been treated with specific antiosteoporotic drugs were recruited from the out-patient clinic database. Bone mineral density was measured by dual-energy X-ray absorptiometry at the lumbar spine and at the left hip. Disease activity measures included: duration of morning stiffness, tender and swollen joint count, patient's and physician's global assessment, presence of dactylitis and enthesitis, ESR, CRP and Disease Activity Score 28. Health Assessment Questionnaire was used to assess functional status. ----- RESULTS: According to WHO definition, spinal osteoporosis was found in 7.2% of patients, total hip osteoporosis in 1.4% of patients and femoral neck osteoporosis in 2.9% of patients. There was no significant association of any of the measures of disease activity with BMD at any site. Higher HAQ scores were associated with lower total hip BMD. ----- CONCLUSIONS: In our sample of patients with psoriatic arthritis we did not find increased prevalence of osteoporosis. There was no association of BMD with indices of disease activity, while negative correlation was found between HAQ and total hip BMD

Tumores malignos de cabeça e pescoço em pacientes com menos de 18 anos de idade

A conduta ideal para os pacientes menores de 18 anos portadores de tumores malignos da região de cabeça e pescoço não é uniforme nos escassos relatos de literatura. Com o objetivo de mostrar e discutir a experiência no atendimento de cinqüenta casos tratados no Serviço de Cirurgia de Cabeça e Pescoço do Complexo Hospitalar Heliópolis, no período de 1978 a 1994, os autores procederam a uma análise retrospectiva de sua casuística. Os tipos histológicos mais freqüentes foram os derivados da linhagem epitelial, 24 casos (48%) e, entre eles, o carcinoma mucoepidermóide. Entre os tumores derivados do tecido mensequimal, os mais freqüentes foram o rabdomiossarcoma e os linfomas. A cavidade oral foi o sítio mais freqüentemente acometido (15 casos, 30%). Entre todos os pacientes, apenas 21 (42%) estavam vivos e sem evidência de doença em atividade por um período que variou de seis meses a 18 anos. Quatorze (28%) pacientes morreram em decorrência de doença não controlada após um período que variou de dez dias a dois anos a contar da data do final do tratamento. De quatorze (28%) pacientes não pudemos obter informações atualizadas de suas condições e foram considerados perdidos de seguimento. Estes tumores não devem ser vistos como neoplasias de adultos localizadas em pacientes pediátricos; devem ser estudados e abordados como uma doença que apresenta características próprias e que exigem, como no adulto, que a primeira intervenção para o diagnóstico ou para o tratamento não seja intempestiva e, de fato, tenha resolubilidade