Thyroid fine needle aspiration: the morphological features on ThinPrep® slide preparations. Eighty cases with histological control

This study had several purposes: to define cytomorphological features of thyroid cells that might be modified by alcohol fixation; to optimize May-Grünwald–Giemsa (MGG) staining on ThinPrep^® (TP; Cytyc Inc., Bexborough, MA, USA) slides and to compare the diagnostic accuracy of slides prepared by a liquid-based method with those obtained by conventional technique. This study included 120 cases of ultrasound-guided fine needle aspiration (FNA) of the thyroid and 55 FNAs performed on surgically resected thyroid specimens. Histological control was available in 80 cases. In the first group of 120 FNAs, a split-sample technique was used for the TP. Three screenings were performed: first, an individual screening of the conventional smears (CS) and of the TP, a second screening to compare cells observed on the TP with the histological control and a third screening to assess the previously defined diagnostic criteria. Twenty-seven TP cases (22%) were considered unsatisfactory for diagnosis compared with 10 in CS (8%). The high rate of unsatisfactory cases with TP is likely to be due to the use of the split-sample technique. The sensitivity was 94% for CS and 81% for TP. The specificity was 67% and 60% for CS and TP, respectively. Two occult papillary carcinomas were missed by both methods. As for the MGG staining, the modified technique used for TP resulted in the same quality as the standard procedure. Conversely, TP did however induce uncommon morphological features. In this study, sensitivity and specificity levels are higher for CS than for TP; the difference may be explained by the fact that the methanol fixative used for TP induces some cytological alterations, especially in oncocytic tumours and lymphocytic thyroïditis.     

Modifications of anionic-lipid domains preceding membrane fusion in guinea pig sperm

The relationship between anionic-lipid concentration and the functional properties of plasma-membrane domains was explored using the guinea-pig sperm membrane as a model, with polymyxin B (PXB) as a probe. Areas of plasmalemma specialized for fusion during the acrosome reaction had a higher affinity for the probe than adjacent nonfusigenic regions. In addition, capacitation--a process preceding acrosome:plasma-membrane fusion--markedly enlarged the area susceptible to PXB binding over the acrosomal cap. Protease treatment mimicked capacitation by increasing the acrosome-reaction incidence as well as PXB binding, at enzyme concentrations not affecting the surface coat nor altering filipin/sterol localization. Both proteolytic digestion and capacitation failed to augment PXB- or filipin-affinity in nonfusigenic zones, such as the post-acrosomal segment, including its particle-free maculae. Incubation of sperm in capacitating medium supplemented with 32P-labeled phosphate, followed by lipid extraction, thin-layer chromatography, and autoradiography, revealed a radioactive band comigrating with cardiolipin and phosphatidic acid. Vermiform protrusions elicited by PXB in the outer lamellae of cardiolipin- phosphatidylcholine liposomes resembled those seen in fusional regions of sperm membrane. We conclude that (a) differing concentrations of anionic lipids are found in adjacent domains of the sperm plasma membrane; (b) these domains mirror the functional regions of the membrane, with higher anionic-lipid concentrations localized over fusional zones; (c) the surface coat does not participate in the maintenance of such domains; (d) anionic-lipid synthesis may contribute to their formation; and (e) anionic-lipid concentrations increase as the membrane becomes fusionally competent, indicating that cellular modulation of lipid domains accompanies regulation of membrane function.     

Galactosyltransferase activities in subcellular fractions of two YC8 lymphoma cell variants: does a relationship exist between antigenic determinants and acceptor sites for galactose?

Experiments have been undertaken to correlate physiological changes, observed in two YC8 cells variants (P and L) and some of their immunological and enzymatic properties. These cell lines show different responses towards antilymphocyte and anti-Moloney sera. Subcellular fractionations have been made. The A fractions (d: 1.14/1.16) have the highest ouabain-inhibited Mg²⁺-stimulated (Na⁺-K⁺)-dependent ATPase and galactosyltransferase activities. Some properties of the latter enzyme have been studied: whereas optima pH and requirements for Mn²⁺ ions have been found to be the same for both cell line enzymes, on the contrary, different kinetic parameters have been shown with respect to sugar donor (UDP-galactose) on endogeneous or exogeneous (ovomucoid) acceptors. Apparent Km for UDP-galactose is 1.7 × 10⁻⁶ M (P-cells) and 3.3 × 10⁻⁶ M (L-cells), on endogeneous acceptors, and P-cell V max < L-cell V max; on ovomucoid it is 0.61 × 10⁻⁶ M, for both cell lines. These results suggest the presence on L-cells of more endogeneous acceptor sites, the higher affinity of P-cells for UDP-galactose being balanced by less endogeneous acceptor sites for galactose. When ovomucoid is added, galactose transfer on endogeneous acceptor sites of both cells is negligible. Apparent Km for ovomucoid is 8.6 × 10⁻⁵ M (P-cells) and 4.3 × 10⁻⁵ M (L-cells). These data support the above-mentioned hypothesis: L-cell enzymes would be more rapidly saturated than P-cell enzymes because of the higher number of endogeneous sites on L-cells.This supposed acquired character of L-cells as well as their immunological behaviour could explain the modified properties of L-cells as compared to P-cells.     

Biodecolourization of azo and triphenylmethane dyes by <Emphasis Type="Italic">Dichomitus squalens</Emphasis> and <Emphasis Type="Italic">Phlebia</Emphasis> spp

Nine white-rot fungal strains were screened for biodecolourization of brilliant green, cresol red, crystal violet, congo red and orange II. Dichomitus squalens, Phlebia fascicularia and P. floridensis decolourized all of the dyes on solid agar medium and possessed better decolourization ability than Phanerochaete chrysosporium when tested in nitrogen-limited broth medium. Journal of Industrial Microbiology & Biotechnology (2002) 28, 201–203 DOI: 10.1038/sj/jim/7000222 Received 12 July 2001/ Accepted in revised form 22 October 2001     

Cryptogein affects expression of alpha3, alpha6 and beta1 20S proteasome subunits encoding genes in tobacco

Twelve alpha and beta 20S proteasome subunits cDNAs showing 70-82% identity with the corresponding genes in Arabidopsis or rice, and features of eukaryotic proteasome subunits were cloned in tobacco. Only beta1-tcI 7, alpha3 and alpha6, 20S proteasome subunits encoding genes were up-regulated by cryptogein, a proteinaceous elicitor of plant defence reactions. These results led to the hypothesis that the activation of beta1-tcI 7, alpha3 and alpha6 could induce a specific proteolysis involved in the hypersensitive response and systemic acquired resistance monitored by cryptogein.     

Poorly conserved ORFs in the genome of the archaea Halobacterium sp. NRC-1 correspond to expressed proteins

MOTIVATION: A large fraction of open reading frames (ORFs) identified as 'hypothetical' proteins correspond to either 'conserved hypothetical' proteins, representing sequences homologous to ORFs of unknown function from other organisms, or to hypothetical proteins lacking any significant sequence similarity to other ORFs in the databases. Elucidating the functions and three-dimensional structures of such orphan ORFs, termed ORFans or poorly conserved ORFs (PCOs), is essential for understanding biodiversity. However, it has been claimed that many ORFans may not encode for expressed proteins. RESULTS: A genome-wide experimental study of 'paralogous PCOs' in the halophilic archaea Halobacterium sp. NRC-1 was conducted. Paralogous PCOs are ORFs with at least one homolog in the same organism, but with no clear homologs in other organisms. The results reveal that mRNA is synthesized for a majority of the Halobacterium sp. NRC-1 paralogous PCO families, including those comprising relatively short proteins, strongly suggesting that these Halobacterium sp. NRC-1 paralogous PCOs correspond to true, expressed proteins. Hence, further computational and experimental studies aimed at characterizing PCOs in this and other organisms are merited. Such efforts could shed light on PCOs' functions and origins, thereby serving to elucidate the vast diversity observed in the genetic material.     

Charged Residues in Surface-located Loops Influence Voltage Gating of Porin from Haemophilus influenzae Type b

Porin of Haemophilus influenzae type b (341 amino acids; M _r 37782) determines the permeability of the outer membrane to low molecular mass compounds. Purified Hib porin was subjected to chemical modification of lysine residues by succinic anhydride. Electrospray ionization mass spectrometry identified up to 12 modifications per porin molecule. Tryptic digestion of modified Hib porin followed by reverse phase chromatography and matrix assisted laser desorption ionization time-of-flight mass spectrometry mapped the succinylation sites. Most modified lysines are positioned in surface-located loops, numbers 1 and 4 to 7. Succinylated porin was reconstituted into planar lipid bilayers, and biophysical properties were analyzed and compared to Hib porin: there was an increased average single channel conductance compared to Hib porin (1.24+/−0.41 vs. 0.85+/−0.40 nanosiemens). The voltage-gating activity of succinylated porin differed considerably from that of Hib porin. The threshold voltage for gating was decreased from 75 to 40 mV. At 80 mV, steady-state conductance for succinylated porin was 50–55% of the instantaneous conductance. Hib porin at 80 mV showed a decrease to 89–91% of the instantaneous current levels. We propose that surface-located lysine residues are determinants of voltage gating for porin of Haemophilus influenzae type b. Received: 11 August 2000/Revised: 8 September 2000