Developing a methodology for three-dimensional correlation of PET-CT images and whole-mount histopathology in non-small-cell lung cancer.

BACKGROUND: Understanding the three-dimensional (3D) volumetric relationship between imaging and functional or histopathologic heterogeneity of tumours is a key concept in the development of image-guided radiotherapy. Our aim was to develop a methodologic framework to enable the reconstruction of resected lung specimens containing non-small-cell lung cancer (NSCLC), to register the result in 3D with diagnostic imaging, and to import the reconstruction into a radiation treatment planning system. METHODS AND RESULTS: We recruited 12 patients for an investigation of radiology-pathology correlation (RPC) in nsclc. Before resection, imaging by positron emission tomography (PET) or computed tomography (CT) was obtained. Resected specimens were formalin-fixed for 1-24 hours before sectioning at 3-mm to 10-mm intervals. To try to retain the original shape, we embedded the specimens in agar before sectioning. Consecutive sections were laid out for photography and manually adjusted to maintain shape. Following embedding, the tissue blocks underwent whole-mount sectioning (4-mum sections) and staining with hematoxylin and eosin. Large histopathology slides were used to whole-mount entire sections for digitization. The correct sequence was maintained to assist in subsequent reconstruction. Using Photoshop (Adobe Systems Incorporated, San Jose, CA, U.S.A.), contours were placed on the photographic images to represent the external borders of the section and the extent of macroscopic disease. Sections were stacked in sequence and manually oriented in Photoshop. The macroscopic tumour contours were then transferred to MATLAB (The Mathworks, Natick, MA, U.S.A.) and stacked, producing 3D surface renderings of the resected specimen and embedded gross tumour. To evaluate the microscopic extent of disease, customized "tile-based" and commercial confocal panoramic laser scanning (TISSUEscope: Biomedical Photometrics, Waterloo, ON) systems were used to generate digital images of whole-mount histopathology sections. Using the digital whole-mount images and imaging software, we contoured the gross and microscopic extent of disease. Two methods of registering pathology and imaging were used. First, selected pet and ct images were transferred into Photoshop, where they were contoured, stacked, and reconstructed. After importing the pathology and the imaging contours to MATLAB, the contours were reconstructed, manually rotated, and rigidly registered. In the second method, MATLAB tumour renderings were exported to a software platform for manual registration with the original pet and ct images in multiple planes. Data from this software platform were then exported to the Pinnacle radiation treatment planning system in DICOM (Digital Imaging and Communications in Medicine) format. CONCLUSIONS: There is no one definitive method for 3D volumetric RPC in nsclc. An innovative approach to the 3D reconstruction of resected nsclc specimens incorporates agar embedding of the specimen and whole-mount digital histopathology. The reconstructions can be rigidly and manually registered to imaging modalities such as ct and pet and exported to a radiation treatment planning system.

A comparison of the distribution of muscle type in the tadpole tails of Xenopus laevis and Rana temporaria: an histological and ultrastructural study.

The types and the distribution of muscle fibres were analysed and compared in the tails of Xenopus laevis and Rana temporaria tadpoles. The filter feeding tadpoles of X. laevis were found to have both white muscle fibres adjacent to the notochord used for normal locomotory swimming and a superficial layer of small red fibres. The red fibres are probably used for the continuous flickering movement of the tail associated with the maintenance of the mid-water filter feeding position. R. temporaria, a grazing detritus feeding tadpole, was found to have only white muscle fibres used for normal locomotory swimming. Smaller superficial fibres were not red fibres but were thought to be immature white fibres.

Aedes albopictus distribution, abundance, and colonization in Lee County, Florida, and its effect on Aedes aegypti.

In 1992 the known southern limit of Aedes albopictus in Florida was in Lee County. Through oviposition surveillance, the distribution of Ae. albopictus was determined, and its frequency relative to Aedes aegypti and colonization pattern of areas previously occupied by Ae. aegypti were examined in Lee County. The data collected in the first year of surveillance demonstrate the ability of Ae. albopictus to rapidly and preferentially colonize large expanses of rural southwest Florida. Urban and suburban areas of the county showed slower colonization rates. In suburban areas, Ae. albopictus became the dominant container-breeding mosquito species, whereas it did not become dominant in urban areas. During the study period, Ae. albopictus did not displace Ae. aegypti in urban or suburban habitats. The southern limit of Ae. albopictus moved a distance of 8.1 km (5 mi.) in 6 wk to the southern border of the county.

Mosquito (Aedes taeniorhynchus) resistance to methoprene in an isolated habitat.

Salt-marsh mosquitoes (Aedes taeniorhynchus), collected on 2 barrier islands in Lee County, Florida, that had been treated from 1989 to 1994 with 150-day methoprene briquets, were bioassayed with technical s-methoprene in the laboratory. Susceptibility of the indigenous Captiva strain (median lethal concentration [LC50] estimate, 6.71 ppb) collected from Captiva Island was 14.9-fold lower than the naive Flamingo strain (LC50 estimate, 0.45 ppb) from Everglades National Park. The Lover's Key strain (LC50 estimate, 6.66 ppb) was 14.8-fold less susceptible than the naive strain. Determinations of the susceptibility of nearby foci of the mainland mosquitoes exposed in the past several years to methoprene have not been completed, but probit analysis of laboratory exposures revealed that the only mainland strain tested (Burnt Store) was no less susceptible (1.06-fold) than the naive Flamingo strain. These findings support the theory that the observed resistance might be restricted to the barrier islands. The known resistance foci (generated with briquet formulations) are located west of the mainland where there is minimal likelihood of inflow of genome from the mainland. On the other hand, the mainland mosquitoes, which were exposed to liquid formulations of methoprene from 1987 to 1994, are believed to have substantial gene flow between exposed and nonexposed populations and thus a reduced likelihood of selection for resistance.

Gene expression at the pink-eyed dilution (p) locus in the mouse is confirmed to be pigment cell autonomous using recombinant embryonic skin grafts.

Sash (Wsh), a viable and fully fertile allele of the dominant spotting (W) locus (Lyon & Glenister, 1982) has been used in a modified test system to investigate the site of gene expression at the pink-eyed dilution (p) locus. Reciprocal recombinant epidermal@dermal skin grafts were constructed from 13-day embryonic skin of p and Wsh homozygotes. Thus in the reciprocal experiments pink-eyed dilution melanocytes were exposed to any environmental influence from the wild-type allele of the p locus in either the epidermis (when WshWsh) or the dermis (when WshWsh). The hair pigmentation of the grafts recovered after three weeks beneath the testicular tunica of adult male mice was always typical of the p phenotype showing that p is melanocyte autonomous. This result was supported by experiments using a modification of Mayer's (1965) neural crest grafting technique and the construction of 14-day recombinant skin grafts. Sash (WshWsh) epidermis can support melanocyte differentiation and pigment production but lacks functional melanocytes. The advantages of Wsh in experimental systems for testing the site of pigment gene expression have been demonstrated. Control experiments confirmed the dermal influence of agouti (A) over non-agouti (a) epidermis but non-agouti dermis did not overrule agouti pink-eyed dilution (AA pp) epidermis suggesting an epistatic effect of p in the melanocyte.

Relation between synovial fluid C3 degradation products and local joint inflammation in rheumatoid arthritis, osteoarthritis, and crystal associated arthropathy.

C3 degradation products (C3dg/d) were estimated in 288 synovial fluid (SF) samples (rheumatoid arthritis (RA) 93, osteoarthritis (OA) 68, chronic pyrophosphate arthropathy 80, acute pseudogout 20, others 27) from knees of 138 patients (bilateral 67, serial sampling on two to six occasions 40). At each aspiration knees were defined as 'active' or 'inactive' by single observer global assessment using six clinical parameters of inflammation. Lack of correlation between paired SF and plasma C3dg/d implied local C3 activation within joints. Raised SF C3d levels were found in active compared with inactive RA joints (mean (range) 51 (15-105) and 6 (0-15) units/ml respectively). Low SF C3dg/d levels were found in OA (mean (range) 0.8 (0-7) units/ml) and chronic pyrophosphate arthropathy (mean (range) 4 (0-16) units/ml), irrespective of clinical activity. In contrast, very high levels (mean (range) 61 (16-126) units/ml) were present in all cases of pseudogout. These differences remained after correction for SF C3 or albumin. This study is the first to show a positive correlation between SF C3dg/d and local inflammation in RA joints. It further suggests that C3 activation is a constant feature of pseudogout but not an accompaniment of inflammation associated with chronic crystal associated synovitis or OA.

Impaired joint mobility in Guillain-Barré syndrome: a primary or a secondary phenomenon?

Three patients with Guillain-Barré syndrome had significant residual impairment of joint mobility. Pain in the limbs and axial skeleton was a prominent early feature, as were autonomic disturbances and bulbar involvement resulting in prolonged mechanical ventilation. All three patients developed marked joint stiffness and contractures despite having physiotherapy from the outset. The skeletal problems and complications became major components of disability despite improving neurological status.

Synovial fluid pyrophosphate and nucleoside triphosphate pyrophosphatase: comparison between normal and diseased and between inflamed and non-inflamed joints.

Deposition of intra-articular calcium pyrophosphate is associated with both aging and arthropathy; increased concentrations of free pyrophosphate (PPi) may contribute to such deposition. Free pyrophosphate and nucleoside triphosphate pyrophosphatase (NTPase) were estimated in synovial fluids from 50 subjects with normal knees and from 44 patients with rheumatoid arthritis, 61 with pyrophosphate arthropathy, and 59 with osteoarthritis. For arthropathic knees clinically assessed inflammation was classified as active or inactive using a summated score of six clinical features. The order of PPi (mumol/l) and NTPase (mumol PPi/30 min/mg protein) was pyrophosphate arthropathy greater than osteoarthritis greater than rheumatoid arthritis (median PPi, NTPase respectively: for pyrophosphate arthropathy 15.9, 0.45; for osteoarthritis 9.3, 0.25; for rheumatoid arthritis 4.4, 0.18), with significant differences between all groups. In pyrophosphate arthropathy both PPi (mumol/l) and NTPase (mumol PPi/30 min/mg protein) were higher than normal (15.9, 0.45 v 8.6, 0.2 respectively), but findings in osteoarthritis did not differ from normal. The inflammatory state of the knee had a distinct but variable effect on synovial fluid findings in rheumatoid arthritis and pyrophosphate arthropathy, but not in osteoarthritis. There was no correlation of either PPi or NTPase with age, or between PPi and NTPase in any group. This study provides in vivo data for synovial fluid PPi and NTPase. It suggests that factors other than PPi need to be considered in a study of crystal associated arthropathy. Clinical inflammation, as well as diagnosis, is important in synovial fluid studies.

Evaluation of enzymatic mutation detectiontrade mark in hereditary nonpolyposis colorectal cancer.

In hereditary nonpolyposis colorectal cancer (HNPCC), the majority of reported mutations are dispersed throughout the 35 exons of the two principal susceptibility genes, MLH1 and MSH2, and because of this complexity, rapid mutation screening methods are required. The aim of this study was to evaluate the sensitivity of the Enzymatic Mutation Detection (EMD) assay in HNPCC using genomic DNA samples with known gene alterations in MLH1 and MSH2. The EMD assay relies upon the enzyme T4 Endonuclease VII recognizing and cleaving DNA mismatches, created when a PCR product containing a sequence alteration is hybridized with a wild type probe. A total of 68 different sequence variants from 30 exons were analyzed. The EMD assay was able to detect 62 of the 68 sequence variants (91%) with the majority showing strong cleavage products. One of the advantages of the EMD assay over other mutation screening techniques is that larger fragments can be analyzed in a single assay. No specialized equipment is required and one set of primers is sufficient for radioactive detection of the cleavage products. This method can be adapted to use fluorescent dye-labelled primers and may be automated to detect mutations accurately and rapidly in a large number of samples. One new MLH1 mutation (418delA) and two novel MSH2 mutations (1A>C; 227-228delAG) were also detected in HNPCC patients screened using this method.

Cloning and characterization of a mouse homologue of the human haematopoietic cell-specific four-transmembrane gene HTm4.

Haematopoietic cell-specific transmembrane-4 (HTm4) is a four-transmembrane protein most closely related to CD20 and the beta subunit of the high affinity receptor for IgE (Fc(epsilon)RIbeta). To date, it has only been described in humans, where it is expressed in haematopoietic cells of both myeloid and lymphoid lineages. The function of HTm4 is unknown; however, as for CD20 and Fc(epsilon)RI-beta, it is likely to play a role in signal transduction as part of a multi-subunit cell surface receptor complex. In this study, we report the cDNA cloning and expression distribution of mouse HTm4. The deduced mouse HTm4 protein is of 213 amino acids, and contains four putative transmembrane domains. Mouse HTm4 shows 62% overall amino acid identity with human HTm4; the transmembrane regions are highly conserved between both species (75% identity), whereas the N- and C-terminal and inter-transmembrane loop regions are more divergent (52%). Interestingly, the N-terminal domain of mouse HTm4 is predicted to be 23 amino acids shorter, and the C-terminal domain 23 amino acids longer, than that of human HTm4. Northern blot and reverse transcriptase (RT)-PCR analysis suggest that mouse HTm4 mRNA is expressed at low levels only in spleen, bone marrow and peripheral blood leucocytes. This is the first report of the cloning of HTm4 from a species other than human, and provides important sequence information towards the understanding of the function of this poorly characterized four-transmembrane molecule.

Synovial fluid calcium pyrophosphate dihydrate crystals and alizarin red positivity: analysis of 3000 samples.

Three thousand synovial fluids (1312 patients: chronic pyrophosphate arthropathy (CPA), 41%; osteoarthritis (OA), 12%; rheumatoid arthritis (RA), 16%) were examined for crystals, including calcium pyrophosphate dihydrate (CPPD), by polarized microscopy (score 0-3); calcific particles, by alizarin red positivity (ARP; 0-3); and total cell count. For 1150 fluids, local joint inflammation was assessed as 'active' or 'inactive' using a summated score of six clinical variables. CPPD and ARP scores did not correlate, but each showed positive correlation with age (P less than 0.01, P less than 0.02 respectively). Pseudogout had the highest mean CPPD score (P less than 0.001); intermittent CPPD positivity (range 8-100%) was seen in serially aspirated CPA joints, and there was no difference in CPPD positivity or score between active and inactive CPA. ARP was most frequent in OA subsets (72% of CPA, 46% of OA, 31% of RA; P less than 0.001). ARP was more frequent in active than inactive OA (P less than 0.05) but showed no association with inflammation in CPA or RA. Cell counts were higher in RA and pseudogout compared to OA and CPA, and in active compared to inactive RA. No correlation was found between ARP or CPPD scores and cell count. Cholesterol crystals were uncommon (0.2%) and showed no disease or joint predilection. In arthritic joints, CPPD and calcific particles particularly associate with the OA process and ageing. CPPD may contribute to acute and other calcific particles to chronic inflammation in OA.

A comparison of normal and pathological synovial fluid.

Synovial fluid from 16 normal subjects was compared with that from 149 patients with a variety of rheumatic disorders. Normal fluid had fewer cells and a lower content of beta-glucuronidase than osteoarthritic samples. Particles, including occasional birefringent crystals, were seen in normal fluids as well as pathological samples. Alizarin red staining particles (presumed to contain apatite) were seen in all diagnostic groups; their numbers showed some correlation with radiological calcification in and around the joints and with a hypertrophic subchondral bone response. Lactate levels were highest in septic arthritis. No assay showed disease specificity.

Natural antibiotic resistance of bacteria isolated from larvae of the oil fly, Helaeomyia petrolei.

Helaeomyia petrolei (oil fly) larvae inhabit the asphalt seeps of Rancho La Brea in Los Angeles, Calif. The culturable microbial gut contents of larvae collected from the viscous oil were recently examined, and the majority (9 of 14) of the strains were identified as Providencia spp. Subsequently, 12 of the bacterial strains isolated were tested for their resistance or sensitivity to 23 commonly used antibiotics. All nine strains classified as Providencia rettgeri exhibited dramatic resistance to tetracycline, vancomycin, bacitracin, erythromycin, novobiocin, polymyxin, colistin, and nitrofurantoin. Eight of nine Providencia strains showed resistance to spectinomycin, six of nine showed resistance to chloramphenicol, and five of nine showed resistance to neomycin. All 12 isolates were sensitive to nalidixic acid, streptomycin, norfloxacin, aztreonam, cipericillin, pipericillin, and cefotaxime, and all but OF008 (Morganella morganii) were sensitive to ampicillin and cefoxitin. The oil fly bacteria were not resistant to multiple antibiotics due to an elevated mutation rate. For each bacterium, the number of resistant mutants per 10(8) cells was determined separately on rifampin, nalidixic acid, and spectinomycin. In each case, the average frequencies of resistant colonies were at least 50-fold lower than those established for known mutator strain ECOR 48. In addition, the oil fly bacteria do not appear to excrete antimicrobial agents. When tested, none of the oil fly bacteria produced detectable zones of inhibition on Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, or Candida albicans cultures. Furthermore, the resistance properties of oil fly bacteria extended to organic solvents as well as antibiotics. When pre-exposed to 20 microg of tetracycline per ml, seven of nine oil fly bacteria tolerated overlays of 100% cyclohexane, six of nine tolerated 10% xylene, benzene, or toluene (10:90 in cyclohexane), and three of nine (OF007, OF010, and OF011) tolerated overlays of 50% xylene-50% cyclohexane. The observed correlation between antibiotic resistance and organic solvent tolerance is likely explained by an active efflux pump that is maintained in oil fly bacteria by the constant selective pressure of La Brea's solvent-rich environment. We suggest that the oil fly bacteria and their genes for solvent tolerance may provide a microbial reservoir of antibiotic resistance genes.

Class sigma glutathione transferase unfolds via a dimeric and a monomeric intermediate: impact of subunit interface on conformational stability in the superfamily.

Solvent-induced equilibrium unfolding of a homodimeric class sigma glutathione transferase (GSTS1-1, EC 2.5.1.18) was characterized by tryptophan fluorescence, anisotropy, enzyme activity, 8-anilino-1-naphthalenesulfonate (ANS) binding, and circular dichroism. Urea induces a triphasic unfolding transition with evidence for two well-populated thermodynamically stable intermediate states of GSTS1-1. The first unfolding transition is protein concentration independent and involves a change in the subunit tertiary structure yielding a partially active dimeric intermediate (i.e., N2 left and right arrow I2). This is followed by a protein concentration dependent step in which I2 dissociates into compact inactive monomers (M) displaying enhanced hydrophobicity. The third unfolding transition, which is protein concentration independent, involves the complete unfolding of the monomeric state. Increasing NaCl concentrations destabilize N2 and appear to shift the equilibrium toward I2 whereas the stability of the monomeric intermediate M is enhanced. The binding of substrate or product analogue (i.e., glutathione or S-hexylglutathione) to the protein's active site stabilizes the native dimeric state (N2), causing the first two unfolding transitions to shift toward higher urea concentrations. The stability of M was not affected. The data implicate a region at/near the active site in domain I (most likely alpha-helix 2) as being highly unstable/flexible which undergoes local unfolding, resulting initially in I2 formation followed by a disruption in quaternary structure to a monomeric intermediate. The unfolding/refolding pathway is compared with those observed for other cytosolic GSTs and discussed in light of the different structural features at the subunit interfaces, as well as the evolutionary selection of this GST as a lens crystallin.

Synovial fluid collagenase in patients with destructive arthritis of the shoulder joint.

We studied synovial fluid (SF) collagenase in 10 women with severe rheumatoid arthritis (RA), 10 with pyrophosphate arthropathy, and 10 with idiopathic destructive disease of the shoulder conforming to a pattern recently described. SF cell counts were highest in the RA group. Particles were detected by polarized light microscopy and alizarin red staining. Crystals were seen in fluids from all 3 groups; pyrophosphate predominated in the pyrophosphate arthropathy group and alizarin red-positive particles in the idiopathic disease group. Collagenase and tissue inhibitor of metalloproteinase levels were estimated in SF after gel filtration. Tissue inhibitor of metalloproteinase activity was detected in all fluids, but tended to be highest in the RA group. Collagenase activity was detected in 3 RA fluids only. In no sample was collagenase found in an active form. These findings support the clinical concept of an aggressive destructive process which sometimes occurs in the shoulder joints of elderly women. Because we were not able to detect free collagenase in SF from any of the patients with idiopathic shoulder disease, the data suggest that high levels of active collagenase are not characteristic of this group of patients.

Equilibrium folding of dimeric class mu glutathione transferases involves a stable monomeric intermediate.

The conformational stabilities of two homodimeric class mu glutathione transferases (GSTM1-1 and GSTM2-2) were studied by urea- and guanidinium chloride-induced denaturation. Unfolding is reversible and structural changes were followed with far-ultraviolet circular dichroism, tryptophan fluorescence, enzyme activity, chemical cross-linking, and size-exclusion chromatography. Disruption of secondary structure occurs as a monophasic transition and is independent of protein concentration. Changes in tertiary structure occur as two transitions; the first is protein concentration dependent, while the second is weakly dependent (GSTM1-1) or independent (GSTM2-2). The second transition corresponds with the secondary structure transition. Loss in catalytic activity occurs as two transitions for GSTM1-1 and as one transition for GSTM2-2. These transitions are dependent upon protein concentration. The first deactivation transition coincides with the first tertiary structure transition. Dimer dissociation occurs prior to disruption of secondary structure. The data suggest that the equilibrium unfolding/refolding of the class mu glutathione transferases M1-1 and M2-2 proceed via a three-state process: N(2) <--> 2I <--> 2U. Although GSTM1-1 and GSTM2-2 are homologous (78% identity/94% homology), their N(2) tertiary structures are not identical. Dissociation of the GSTM1-1 dimer to structured monomers (I) occurs at lower denaturant concentrations than for GSTM2-2. The monomeric intermediate for GSTM1-1 is, however, more stable than the intermediate for GSTM2-2. The intermediates are catalytically inactive and display nativelike secondary structure. Guanidinium chloride-induced denaturation yields monomeric intermediates, which have a more loosely packed tertiary structure displaying enhanced solvent exposure of its tryptophans and enhanced ANS binding. The three-state model for the class mu enzymes is in contrast to the equilibrium two-state models previously proposed for representatives of classes alpha/pi/Sj26 GSTs. Class mu subunits appear to be intrinsically more stable than those of the other GST classes.

Identification of active-site residues of the pro-metastatic endoglycosidase heparanase.

Heparanase is a beta-D-endoglucuronidase that cleaves heparan sulfate (HS) and has been implicated in many important physiological and pathological processes, including tumor cell metastasis, angiogenesis, and leukocyte migration. We report herein the identification of active-site residues of human heparanase. Using PSI-BLAST and PHI-BLAST searches of sequence databases, similarities were identified between heparanase and members of several of the glycosyl hydrolase families (10, 39, and 51) from glycosyl hydrolase clan A (GH-A), including strong local identities to regions containing the critical active-site catalytic proton donor and nucleophile residues that are conserved in this clan of enzymes. Furthermore, secondary structure predictions suggested that heparanase is likely to contain an (alpha/beta)(8) TIM-barrel fold, which is common to the GH-A families. On the basis of sequence alignments with a number of glycosyl hydrolases from GH-A, Glu(225) and Glu(343) of human heparanase were identified as the likely proton donor and nucleophile residues, respectively. The substitution of these residues with alanine and the subsequent expression of the mutant heparanases in COS-7 cells demonstrated that the HS-degrading capacity of both was abolished. In contrast, the alanine substitution of two other glutamic acid residues (Glu(378) and Glu(396)), both predicted to be outside the active site, did not affect heparanase activity. These data suggest that heparanase is a member of the clan A glycosyl hydrolases and has a common catalytic mechanism that involves two conserved acidic residues, a putative proton donor at Glu(225) and a nucleophile at Glu(343).

Quorum sensing in the dimorphic fungus Candida albicans is mediated by farnesol.

The inoculum size effect in the dimorphic fungus Candida albicans results from production of an extracellular quorum-sensing molecule (QSM). This molecule prevents mycelial development in both a growth morphology assay and a differentiation assay using three chemically distinct triggers for germ tube formation (GTF): L-proline, N-acetylglucosamine, and serum (either pig or fetal bovine). In all cases, the presence of QSM prevents the yeast-to-mycelium conversion, resulting in actively budding yeasts without influencing cellular growth rates. QSM exhibits general cross-reactivity within C. albicans in that supernatants from strain A72 are active on five other strains of C. albicans and vice versa. The QSM excreted by C. albicans is farnesol (C(15)H(26)O; molecular weight, 222.37). QSM is extracellular, and is produced continuously during growth and over a temperature range from 23 to 43 degrees C, in amounts roughly proportional to the CFU/milliliter. Production is not dependent on the type of carbon source nor nitrogen source or on the chemical nature of the growth medium. Both commercial mixed isomer and (E,E)-farnesol exhibited QSM activity (the ability to prevent GTF) at a level sufficient to account for all the QSM activity present in C. albicans supernatants, i.e., 50% GTF at ca. 30 to 35 microM. Nerolidol was ca. two times less active than farnesol. Neither geraniol (C(10)), geranylgeraniol (C(20)), nor farnesyl pyrophosphate had any QSM activity.