Cellular conditions that modulate the fungicidal activity of occidiofungin.

AIMS: To identify cellular conditions that significantly alter susceptibility of Saccharomyces cerevisiae, Candida albicans and Candida glabrata to the antimicrobial peptide, occidiofungin. METHODS AND RESULTS: Genetic and pharmacological approaches were used to determine a role for calcium signalling in occidiofungin sensitivity profiles for S. cerevisiae, C. albicans and C. glabrata strains of yeast. Minimum inhibitory concentration (MIC) and drop assays found that extracellular calcium resulted in a fourfold resistance, and this was independent of an intact calmodulin-calcineurin signalling pathway. A similar resistance was found in the presence of magnesium but not other cations. Occidiofungin was found to be ineffective against cells in a quiescent state when measured by MIC, drop assay and short-term time-kill assays. A similar resistance pattern was detected for S. cerevisiae cultures pre-exposed to cycloheximide or placed in depleted media conditions. CONCLUSIONS: Extracellular calcium results in fungal tolerance to occidiofungin bioactivity outside of the calmodulin-calcineurin pathway. In addition, the resistance of quiescent cells suggests that active cellular growth is a requirement for occidiofungin's mechanism of action. SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of cellular conditions that have a role in the activity of occidiofungin provided insight into potential cellular targets of this novel antifungal.

Mechanisms of Porphyroblast Crystallization: Results from High-Resolution Computed X-ray Tomography.

Quantitative three-dimensional analysis of rock textures is now possible with the use of high-resolution computed x-ray tomography. When applied to metamorphic rocks, this technique provides data on the sizes and positions of minerals that allow mechanisms of porphyroblast crystallization to be identified. Statistical analysis of the sizes and spatial disposition of thousands of garnet crystals in three regionally metamorphosed rocks with diverse mineralogies, in conjunction with simple numerical models for crystallization, reveals in all cases the dominance of crystallization mechanisms whose kinetics are governed by rates of intergranular diffusion of nutrients.

Small-molecule-based strategies for controlling gene expression.

A central goal in chemical biology is to gain control over biological pathways using small molecules, and the mRNA-synthesizing machinery is a particular important target. New advances in our understanding of transcriptional regulation suggests strategies to manipulate these pathways using small molecules.

Scope, limitations and mechanistic aspects of the photo-induced cross-linking of proteins by water-soluble metal complexes.

BACKGROUND: Chemical cross-linking is a valuable tool with which to study protein-protein interactions. Recently, a new kind of cross-linking reaction was developed in which the photolysis of associated proteins with visible light in the presence of ammonium persulfate and tris(2,2'-bipyridyl)ruthenium(II) dication or palladium(II) porphyrins results in rapid and efficient covalent coupling (Fancy, D.A. & Kodadek, T. (1999). Proc. Natl. Acad. Sci. USA 96, 6020-6024 and Kim, K., Fancy, D.A. & Kodadek, T. (1999). J. Am. Chem. Soc. 121, 11896-11897). Here, mechanistic and practical aspects of the reaction of importance for its application to biochemical problems are examined. RESULTS: It is shown that the photo-initiated cross-linking chemistry can be optimized for the analysis of protein-protein interactions in crude cell extracts. A number of commonly used epitope or affinity tags survive the reaction in functional form, allowing the simple visualization of the cross-linked products, or their isolation. It is shown that very little light-independent oxidation of protein residues occurs and that significant perturbation of complexes of interest prior to the brief photolysis period does not occur. Finally, evidence is presented that is consistent with a mechanistic model in which ammonium persulfate functions simply as an electron acceptor, facilitating the generation of the key high valent metal complex from the photoexcited species by electron transfer. In the absence of an electron acceptor, a much lower efficiency reaction is observed that appears to involve products resulting from reaction of the excited state metal complex with molecular oxygen. CONCLUSIONS: These results provide useful practical information for chemists and biochemists who may wish to employ this new cross-linking chemistry for the analysis of protein complexes. They also shed new light on the mechanism of this interesting reaction.

Critical evaluation of the cocaine test in the diagnosis of Horner's syndrome.

We evaluated the effectiveness of the cocaine test for diagnosing Horner's syndrome. The test was administered to 119 patients with a diagnosis of Horner's syndrome and to 50 normal subjects. We compared the cocaine-induced anisocoria in the two groups by measuring photographs of the pupils. We found the cocaine test to be highly effective in separating normal subjects from patients with Horner's syndrome. The chances of having Horner's syndrome increased with the amount of cocaine-induced anisocoria. Through the use of logistic regression analysis, we determined the odds ratio of having Horner's syndrome compared with not having it for each 0.1-mm increment of anisocoria measured after cocaine administration. A postcocaine anisocoria value of 0.8 mm gave a mean odds ratio of approximately 1050:1 that Horner's syndrome was present (lower 95% confidence limit = 37:1). We found that simply measuring the postcocaine anisocoria provided a better prediction of Horner's syndrome than taking the trouble to calculate the net change in anisocoria. Odds ratios should help the clinician decide if the result of a cocaine test is indicative of Horner's syndrome.

Palpebral fissure responses to topical adrenergic drugs.

We measured the magnitude and time course of the increase in palpebral fissure width in ten normal volunteers in response to direct-acting (2.5% phenylephrine, 1% apraclonidine) and indirect-acting (10% cocaine, 1% hydroxyamphetamine) topical adrenergic drugs given in one eye. The increase in the palpebral fissure width of the treated eye was compared to the width of the untreated, control eye during a period of 60 minutes after each drug was administered. The difference in fissure width (asymmetry) between the treated and untreated eyes increased significantly for all drugs during the three- to 60-minute time period after treatment. There was no significant difference in the maximum eyelid effect among the adrenergic drugs tested. The drugs exerted their maximum effect by 30 minutes in 39 of the 40 trials (97.5%). The direct-acting drugs tended to exert their effect more quickly than the indirect-acting drugs. Our results demonstrate the expected increase in palpebral fissure width in response to topical adrenergic drugs in normal eyes. This information will provide a basis for evaluating Müller's muscle and its sympathetic innervation in patients with blepharoptosis.

Image-guided core breast biopsy of ductal carcinoma in situ presenting as a non-calcified abnormality.

OBJECTIVE: Ductal carcinoma in situ (DCIS) typically presents as calcifications which are detected mammographically. Our aim was to evaluate the less common presentations of ductal carcinoma in situ diagnosed by image-guided core biopsy and correlate with histopathologic diagnoses. METHODS AND MATERIAL: Imaging and histopathologic findings were retrospectively reviewed in 11 patients with ductal carcinoma in situ diagnosed at core biopsy that presented as noncalcified radiographic abnormalities. RESULTS: Mammography showed non-calcified, circumscribed nodules, ill-defined nodules and architectural distortion. In two patients, no mammographic abnormality was detected. Sonography showed circumscribed, round or oval, solid masses; irregular, heterogeneous masses; and a tubular structure. Histopathologic diagnoses included multiple architectural subtypes and ranged from low to high nuclear grade. CONCLUSION: Although image-guided core biopsy diagnosis of ductal carcinoma is typically made when sampling calcifications, DCIS can be diagnosed following biopsy of non-calcified masses or distortion. There is no correlation between histopathologic subtype and radiologic appearance.

Spindle cell lipoma of the breast. A case report.

A case of spindle cell lipoma of the breast found on mammography in a 53-year-old woman is presented. This rare type of tumor has been previously reported on only after its presentation as a palpable mass. Radiographically it appears as a well-circumscribed mass. Ultrasonographically it appears as a homogeneously hyperechoic nodule. Histologically these lesions are composed of spindle cells intermingled with adipocytes.

Forensic palaeontology: The Archaeoraptor forgery.

The Archaeoraptor fossil was announced as a 'missing link' and purported to be possibly the best evidence since Archaeopteryx that birds did, in fact, evolve from certain types of carnivorous dinosaur. It reportedly came from Early Cretaceous beds of China that have produced other spectacular fossils transitional between birds and extinct non-avian dinosaurs. But Archaeoraptor was revealed to be a forgery in which bones of a primitive bird and a non-flying dromaeosaurid dinosaur had been combined. Here we use high-resolution X-ray computed tomography (CT) to determine the nature and extent of the forgery, as well as how it was built, by imaging the fracture pattern and distribution of materials through the entire specimen.

Biochemical characterization of the TATA-binding protein-Gal4 activation domain complex.

It has been suggested that complexes between gene-specific activators and the TATA-binding protein (TBP) play an important role in the expression of many genes. However, few detailed studies of well defined activator-TBP complexes have been reported. An analysis of the biochemical properties of the complex formed by the acidic activation domain (AAD) of the yeast activator Gal4 and TBP is presented here. This is shown to be composed of two AAD and one TBP molecule. DNA binding experiments reveal that TATA-containing DNAs and the Gal4 AAD bind TBP competitively, suggesting that the AAD and TATA boxes recognize overlapping surfaces of TBP. The kinetics of the formation and dissociation of the AAD(2)-TBP complex is also probed. The impact of these findings on models for Gal4-mediated transcriptional activation is considered.

Pseudoangiomatous stromal hyperplasia: mammographic and sonographic appearances.

OBJECTIVE: Pseudoangiomatous stromal hyperplasia is a benign, localized form of stromal overgrowth with a probable hormonal etiology. Our purpose is to describe the mammographic, sonographic, and clinical features of this entity. MATERIALS AND METHODS: A retrospective review of breast imaging studies and demographic information for seven patients identified as having pseudoangiomatous stromal hyperplasia was performed. The patients were chosen from a 1-year period during which 1661 breast biopsies were performed. RESULTS: The patients were 36-61 years old. Six were premenopausal, and the one postmenopausal woman was on hormone replacement therapy. Three patients wee evaluated palpable breast lumps, and four were asymptomatic. All seven women had noncalcified masses that measured 1.1-11 cm and that were visible by mammography. The border characteristics were as follows: three masses were well circumscribed, two were partly circumscribed, and two were indistinct, probably because they were obscured by overlying parenchyma. Sonography was performed for five patients; lesions were visible in four. All four of these lesions were solid and circumscribed. Five of the masses had increased in size since earlier studies, and one palpable mass was found by physical examination to have grown over time. Two patients had a local recurrence of pseudoangiomatous stromal hyperplasia. Surgical excision was performed for three patients, large-core biopsy was performed for three patients, and both surgery and large-core biopsy were performed for one patient. CONCLUSION: Pseudoangiomatous stromal hyperplasia should be included in the differential diagnosis of a circumscribed or partially circumscribed mass, especially in the premenopausal population. These masses often grow over time and can recur locally. Pathologic diagnosis of the lesion may be difficult unless the pathologist is aware of the presence of a mass lesion and appreciates the stromal changes characteristic of such a lesion.

Seat belt injuries of the breast: findings on mammography and sonography.

OBJECTIVE: The purpose of this study was to determine the mammographic and sonographic findings of injuries of the breast caused by seat belts in automobile accidents. The imaging findings of such injuries must be differentiated from those of carcinoma, so that inappropriate treatment is avoided. MATERIALS AND METHODS: Five patients who had breast injuries caused by seat belts with shoulder restraints between 1988 and 1993 and who underwent mammography were included in this study. Four of these women had imaging studies done in our department, and one was examined elsewhere. The initial mammograms for four patients were obtained 1-2 months after trauma to the breast. For the fifth patient, the initial study was obtained 13 months after injury. For all women, follow-up examinations were performed from 3 months to 4 years after injury. Two patients also underwent sonography of the breast during the course of their evaluation. RESULTS: At 1-2 months after breast injury caused by a seat belt, mammograms showed thin-walled fat-density cysts in a linear distribution and, in less dense breasts, an associated 2-3-cm band of increased density. The band of increased density was not seen in more dense breasts. These findings correlated with the line of contusion across the breast and resultant fat necrosis, which ultimately led to the formation of lipid cysts. By 3-4 months after the injury, the lipid cysts and contusion were less apparent, and a line of fibrosis had developed. On sonography, the lipid cysts were smoothly marginated; such cysts may be either anechoic or hypoechoic. Parenchymal calcification may develop 3.5-4 years after such an injury. CONCLUSION: Mammograms in women with breast injuries caused by seat belts show areas of contusion, lipid cysts, and parenchymal calcifications occurring in a bandlike distribution corresponding to the path of the seat belt shoulder restraint across the chest. Lipid cysts are seen sonographically as smoothly marginated anechoic or hypoechoic nodules.

Usefulness of the routine magnification view after breast conservation therapy for carcinoma.

PURPOSE: To assess the usefulness of the routine supplementary magnification view in patients who have undergone breast conservation therapy. MATERIALS AND METHODS: Four hundred seventy-one mammograms in 392 patients were evaluated. Conventional craniocaudal and mediolateral oblique views were obtained in each patient. After a preliminary interpretation was made, a magnification view of the excision site was evaluated and any additional information was documented. RESULTS: In 115 examinations (24%), the magnification view was considered necessary to better evaluate equivocal or questionable calcifications seen on standard views. In 18 cases (4%), review of the magnification view influenced the decision to perform biopsy. None of the magnification views that were considered unnecessary caused the interpretation made from conventional views to be altered. CONCLUSION: Magnification mammographic views should be obtained in patients who have undergone breast conservation therapy only when considered necessary after review of findings on conventional views.

Fibrous nodules found at large-core needle biopsy of the breast: imaging features.

PURPOSE: To describe the imaging and histologic features of large-core needle biopsy (LCNB) specimens of fibrous nodules. MATERIALS AND METHODS: Of 853 breast masses in which LCNB was performed, 38 (4%) revealed histologic findings of fibrous nodules. Repeat biopsy was performed in 16 lesions (surgical excision, 13 lesions; repeat LCNB, three lesions). The mammographic and ultrasonographic findings in these 16 cases, the histologic LCNB findings, and the repeat biopsy findings were retrospectively reviewed. RESULTS: Repeat biopsy findings confirmed the diagnosis of fibrous nodules in 15 of the 16 masses. In one mass, repeat LCNB findings showed a fibroadenoma. The imaging features of the fibrous nodules varied. Five nodules (33%) manifested as masses with indistinct margins; six (40%), as circumscribed masses. In four cases (27%), imaging suggested malignancy. None were calcified masses. An additional 22 masses had circumscribed or indistinct borders and were diagnosed with LCNB as fibrous nodules. None of these masses had suspicious findings, and repeat biopsy was not performed. CONCLUSION: Fibrous nodules usually manifest as masses with circumscribed or indistinct margins but can have findings suggestive of malignancy. LCNB can reveal histologic findings consistent with this diagnosis. In all masses in which repeat biopsy was performed, the diagnosis of a fibrous nodule was confirmed or another benign stromal lesion was diagnosed.

Epidermal inclusion cysts of the breast: three lesions with calcifications.

PURPOSE: To determine whether there are any mammographic and ultrasonographic (US) features of epidermal inclusion cysts of the breast, including heterogeneous microcalcifications, that may be used to preclude unnecessary biopsy. MATERIALS AND METHODS: Clinical history and imaging findings in 15 patients who had undergone surgical excision of an epidermal inclusion cyst were reviewed. RESULTS: In 11 patients, imaging findings of an epidermal inclusion cyst were noted, including 10 patients with mammographic findings, one with US findings only, and seven with mammographic and US findings. The most common mammographic finding (in nine of 10 patients) was an isodense to high-density mass with a circumscribed margin; three circumscribed masses had multiple associated heterogeneous microcalcifications. In the seven patients with corresponding US findings, a circumscribed hypoechoic mass with through transmission was depicted. An additional US feature in six patients was extension of the mass into the dermis. CONCLUSION: Biopsy may be deemed unnecessary if the characteristic US and physical examination findings are present, even in the case of a cyst with heterogeneous microcalcifications.

Stereotactic breast biopsy of clustered microcalcifications with a directional, vacuum-assisted device.

The success rate with the traditional 14-gauge, core-biopsy, multiple-pass technique was compared with that of a directional vacuum-assisted device in sampling calcification clusters in the breast. Of the 130 focal calcification clusters sampled with the multiple-pass technique, 12 clusters (9.2%) had no particles depicted on radiographs of the specimen. Specimens from all 106 (100%) clusters sampled with the directional, vacuum-assisted instrument contained calcifications at radiography. The directional, vacuum-assisted device improved the ability to percutaneously sample breast calcifications.

Evaluation of nonpalpable solid breast masses with stereotaxic large-needle core biopsy using a dedicated unit.

OBJECTIVE: In our institution for the past 4 years, stereotaxic core breast biopsy using a 14-gauge needle has been offered as an alternative to surgical excision. The purpose of this paper is to describe our protocol, results, and lessons learned from our experience. MATERIALS AND METHODS: From August 1991 to July 1995, 388 stereotaxic needle core biopsies of clinically occult, noncalcified, mammographically detected solid masses were performed. In this group, 103 patients underwent subsequent surgical excision. Another 169 have had follow-up examinations 1 year or more after their biopsies. RESULTS: Of the 61 patients diagnosed with a malignant process on core biopsy, all had confirmation on subsequent surgical excision. Forty-one of the 42 core biopsies that showed a benign process were subsequently confirmed on surgical excision. One patient with atypical ductal hyperplasia on core biopsy had ductal carcinoma in situ on surgical excision. Patients with 169 benign masses on core biopsy have been followed for at least 1 year by mammography. Of these women, 110 have been followed for at least 2 years, and no malignant lesions have been found. CONCLUSION: Stereotaxic large-needle core biopsy appears to be an accurate alternative to surgical excision for evaluating a solid breast mass. However, the mammographic appearance, technical quality of the biopsy, and pathologic findings in each patient must be correlated to ensure the highest possible accuracy when using this technique.

Interferometric seeing measurements on Mt. Wilson: power spectra and outer scales.

We have measured power spectra of atmospheric phase fluctuations with the Mark III stellar interferometer on Mt. Wilson under a wide variety of seeing conditions. On almost all nights, the high-frequency portions of the temporal power spectra closely follow the form predicted by the standard Kolmogorov-Tatarski model. At lower frequencies, a variety of behavior is observed. On a few nights, the spectra clearly exhibit the low-frequency flattening characteristic of turbulence with an outer-scale length of the order of 30 m. On other nights, examination of individual spectra yields no strong evidence of an outer scale less than a few kilometers in size, but comparison of the spectra on different interferometer baselines shows a saturation of the spatial structure function on long baselines. This saturation is consistent with the assumption of an outer-scale length similar to that derived for the nights when low-frequency flattening of the spectra is clearly seen. We discuss possible explanations of this behavior and conclude that power spectra from a single interferometer baseline are a poor diagnostic for the effective outer scale compared with multiple-baseline spectra.

The utility of ultrasonographically guided large-core needle biopsy: results from 500 consecutive breast biopsies.

Five hundred ultrasonographically guided large-core needle breast biopsies of solid masses were performed in 446 women. Histopathologic results were correlated with imaging findings. Ultrasonographically guided large-core needle biopsy resulted in diagnosis of malignancy (n = 124) or severe atypical ductal hyperplasia (n = 4) in 128 lesions (26%). In the remaining 372 lesions (74%), ultrasonographically guided large-core needle biopsy yielded benign pathologic results. Follow-up of more than 1 year (n = 225), results of surgical excision (n = 50), or both were obtainable in 275 (74%) of the benign lesions. No malignancies were discovered at surgical excision or during follow-up of this group of benign lesions. There were no complications related to large-core needle biopsy that required additional treatment. Ultrasonographically guided large-core needle biopsy is a safe and accurate method for evaluating breast lesions that require tissue sampling.

Atypical ductal hyperplasia and ductal carcinoma in situ as revealed by large-core needle breast biopsy: results of surgical excision.

OBJECTIVE: This investigation compares the frequency of histologic underestimation of breast carcinoma that occurs when a large-core needle biopsy reveals atypical ductal hyperplasia or ductal carcinoma in situ with the automated 14-gauge needle, the 14-gauge directional vacuum-assisted biopsy device, and the 11-gauge directional vacuum-assisted biopsy device. SUBJECTS AND METHODS: Evaluation of 428 large-core needle biopsies yielding atypical ductal hyperplasia (139 lesions) or ductal carcinoma in situ (289 lesions) was performed. The results of subsequent surgical excision were retrospectively compared with the needle biopsy results. RESULTS: For lesions initially diagnosed as ductal carcinoma in situ, underestimation of invasive ductal carcinoma was significantly less frequent using the 11-gauge directional vacuum-assisted biopsy device when compared with the automated 14-gauge needle (10% versus 21%, p < 0.05) but was not significantly less frequent when compared with the 14-gauge directional vacuum-assisted device (10% versus 17%, p > 0.1). For lesions diagnosed initially as atypical ductal hyperplasia, underestimation of ductal carcinoma in situ and invasive ductal carcinoma was significantly less frequent using the 11-gauge directional vacuum-assisted biopsy device compared with the 14-gauge directional vacuum-assisted device (19% versus 39%, p = 0. 025) and with the automated 14-gauge needle (19% versus 44%, p = 0. 01). CONCLUSION: The frequency of histologic underestimation of breast carcinoma in lesions initially diagnosed as atypical ductal hyperplasia or ductal carcinoma in situ using large-core needle biopsy is substantially lower with the 11-gauge directional vacuum-assisted device than with the automated 14-gauge needle and with the 14-gauge directional vacuum-assisted device.