Cytologic features of focal papillary thyroid carcinoma arising within follicular adenoma: a masked cytomorphologic analysis of 17 cases.

BACKGROUND/OBJECTIVE: Focal papillary thyroid carcinoma (PTC) arising within a follicular adenoma (PTCFA) represents a clinically significant, but rare, histopathologic subset of papillary carcinomas whose cytologic features have not been well described. This uncommon presentation of PTC may contribute to a subset of thyroid aspirates interpreted as 'atypia of undetermined significance/follicular lesion of undetermined significance' (AUS/FLUS). STUDY DESIGN: Seventeen fine-needle aspiration biopsy (FNAB) cases diagnosed as 'PTCFA' on corresponding surgical excision were identified from the archival records of 2 large academic medical centers. A control group of 40 FNAB comprised of 20 follicular adenomas (FA) and 20 PTC was identified (based on the corresponding surgical pathology diagnosis) for comparison. All 57 FNAB were reviewed in a masked fashion and scored for a series of 31 cytomorphologic features. The intraclass correlation between diagnostic categories and overall agreement between cytopathologists was statistically evaluated. RESULTS: Aspirates of PTCFA were originally diagnosed as 'negative' (n = 3), 'AUS/FLUS' (n = 7), 'suspicious for a follicular neoplasm' (n = 3), 'suspicious for malignancy' (n = 3), and 'malignant' (n = 1). On masked review, the most common cytomorphologic features of PTCFA were a nonmacrofollicular cytoarchitectural pattern (71%), medium-large cell size (74%), and micronucleoli (79%). Intranuclear pseudoinclusions and a papillary architecture were absent in 85 and 88% of the cases, respectively. Relative to the 2 control groups, the PTCFA cases demonstrated overlapping features between FA and PTC for the majority of the 31 examined cytomorphologic features. CONCLUSION: PTCFA represent a rare subset of PTC that is difficult to recognize as PTC by FNAB. Most cases exhibit overlapping features between a benign thyroid nodule and conventional PTC, and they are often interpreted as 'AUS/FLUS'.

The iodinated radiographic contrast medium iohexol mimics the vasodilator effect seen with small increases in extracellular K+ in the isolated rabbit central ear artery.

PURPOSE: To investigate whether iodinated radiographic contrast media (IRCM) mimic the hyperpolarizing and vasodilator effects of K+ by comparing the vasodilator effect of a transient rise in extracellular K+ with that of the IRCM iohexol. MATERIAL AND METHODS: Immersed rabbit central ear arterial rings with and without endothelium and pre-contracted with phenylephrine (PE) were used to investigate the dependency of the endothelium in K+-induced vasodilatation. Perfused rabbit central ear arteries, pre-contracted with PE, were used to study the effects of bolus administrations of the IRCM iohexol or KCl on arterial tone under conditions that mimic those employed during clinical arteriography. RESULTS: A small rise in K+ caused an endothelium-independent and ouabain-sensitive relaxation of PE-constricted rabbit central ear artery rings. The relaxation was not changed in the presence of barium. The IRCM iohexol and KCl, injected as boluses into perfused PE-constricted rabbit ear arteries, caused transient decreases in perfusion pressure. Iohexol- and K+-induced pressure decreases were significantly reduced in the presence of 10 microM ouabain alone or in combination with 30 microM barium. Neither iohexol- nor K+-induced pressure decrease was significantly changed in the presence of barium alone compared to controls. CONCLUSION: The vasodilator effect of IRCM mimics the vasodilator effect seen upon small increase in extracellular K+. Under the experimental conditions employed in the present study, a considerable part of the IRCM-induced vasodilatation appears to be due to activation of Na+/K+-ATPase in the smooth muscle cells.

Cytologic findings in granular cell tumors, with emphasis on the diagnosis of malignant granular cell tumor by fine-needle aspiration biopsy.

BACKGROUND: Granular cell tumors (GCTs) are uncommon tumors of putative schwannian derivation that are rarely malignant. Although recent studies have addressed a histologic correlation with malignant behavior, similar studies have not been done on cytologic material. METHODS: The authors evaluated 3 malignant GCTs and 17 benign GCTs (comprising 17 fine-needle aspiration biopsy samples and 3 samples from direct scrapes) for the following cytologic features: hyperchromasia; coarse chromatin; nuclear-to-cytoplasmic (N/C) ratio; nuclear pleomorphism; and vesicular nuclei with enlarged nucleoli, mitoses, necrosis, and spindle cell morphology. RESULTS: Hyperchromasia, coarse chromatin, increased N/C ratio, nuclear pleomorphism, and vesicular nuclei with enlarged nucleoli and spindle cell morphology were associated the most closely with malignancy when they were present throughout the cytologic sample. All were diffusely present in three of three malignant tumors, except vesicular nuclei and spindle cell morphology, which were present diffusely in two tumors and focally in one tumor. By contrast, although one to five of these features were present focally in 8 of 17 benign GCTs, none was present diffusely in any benign GCTs, with one exception, which had a combination of focal nuclear pleomorphism and hyperchromasia together with diffuse vesicular nuclei, large nucleoli, and coarse chromatin. The N/C ratio in this tumor was not increased, and there were no spindle cells or mitoses. Mitoses were present in 2 of 3 malignant GCTs and absent from all 17 benign GCTs. Necrosis was not seen in any tumors. CONCLUSIONS: Malignant GCTs have characteristic cytologic features that differ from those of benign GCTs. However, morphologic heterogeneity precludes definitive classification of some tumors by cytologic features alone.

Papanicolaou smear sensitivity for the detection of adenocarcinoma of the cervix: a study of 49 cases.

BACKGROUND: Papanicolaou smear sensitivity for cervical adenocarcinoma (CVCA) is not well established. Also uncertain are the relative contributions to falsely negative diagnoses of sampling, screening, and interpretive errors. METHODS: Papanicolaou smears were identified from all patients at our institutions with biopsy-proven cervical adenocarcinoma from 1988-1998. All available negative and unsatisfactory smears were reviewed. RESULTS: Of 49 patients with CVCA, 66 smears initially diagnosed as negative and 4 smears initially diagnosed as unsatisfactory from 30 patients were identified. Thirty-two negative smears and 4 unsatisfactory smears from 19 patients were available for review. The retrospective diagnoses in the cases initially called negative were: unsatisfactory in 2, negative in 15, and atypical glandular cells consistent with either adenocarcinoma in situ (AIS) or CVCA in 15. Three of four smears initially called unsatisfactory had neoplastic glandular cells identified retrospectively. The 18 falsely negative or falsely unsatisfactory smears were from 13 patients obtained up to 5 years before biopsy diagnosis. These smears contained neoplastic cells likely to have been mistaken for lower segment endometrial cells (LUS) or endocervical cells with tubal metaplasia (TM) in 11, reactive endocervical cells in 6, and both in 1. In 16 of the 18 smears, the abnormal cells were abundant, although preservation was suboptimal in 6. CONCLUSIONS: Sensitivity of a single Papanicolaou smear for CVCA was between 45% and 76% depending on the classification of negative slides that were not available for review, comparable to previously reported sensitivity for AIS. The diagnostic false-negative or false-unsatisfactory rate in reviewed smears was 50% (18 of 36). Diminished sensitivity is due to the under recognition of glandular neoplasia resembling LUS, TM, or reactive endocervical cells. Cancer (Cancer Cytopathol)

Extensively keratinized squamous intraepithelial lesions of the cervix are difficult to grade.

We tested the hypothesis that extensively keratinized squamous intraepithelial lesions (SILs) are difficult to grade precisely by identifying 100 Papanicolaou smears with a keratinizing SIL that had been originally judged difficult to grade. Of these, 65 were confirmed as low-grade SIL (LSIL) or high-grade SIL (HSIL) on subsequent biopsy. The 65 smears were reviewed independently by 3 cytopathologists who graded each case as LSIL or HSIL (by Bethesda System criteria). The accuracy of the grade was determined by the subsequent biopsy results; accuracy was compared with that of a historic control group of SILs with biopsy follow-up. In the study group, biopsies showed LSIL in 41 cases and HSIL in 24. The mean accuracy for a smear diagnosis of LSIL was 60% for the study group and 92% for the control group. For a smear diagnosis of HSIL, the accuracy was 60% for the study group and 95% for the control group. The overall kappa value for the study group confirmed poor interobserver agreement. Some keratinizing SILs are difficult if not impossible to grade precisely using standard criteria. For such lesions, the diagnosis "SIL, grade cannot be determined due to extensive keratinization" is justified.

Diagnostic utility of calretinin immunohistochemistry in cytologic cell block preparations.

BACKGROUND: Calretinin (CR) is a valuable marker in the immunohistochemical distinction between malignant mesothelioma (MM) and adenocarcinoma (ACA) in tissue sections. However, there is limited and conflicting data regarding the utility of CR in this differential diagnosis on cytologic material, especially cell block preparations. Also, the possible role of CR in the distinction of papillary serous borderline tumor (SBT) cells from reactive mesothelial cells in peritoneal washings has not been examined. METHODS: Formalin-fixed paraffin-embedded cell block specimens of cytologic fluids, washings, and aspirates with a suspicious or positive cytologic diagnosis and a confirmed diagnosis of MM (29 cases), ACA (39 cases), and SBT (10 cases) were used for CR immunohistochemistry (IHC). RESULTS: Moderate to strong staining in > 50% of tumor cells was noted in 26 of 29 (90%) MMs but in only 3 of 39 (8%) ACAs and 1 of 10 (10%) SBTs. Admixed reactive mesothelial cells (when present) were strongly positive in all fluid specimens, but the staining pattern of benign non-reactive mesothelial cells in washing specimens was less reliable. CONCLUSIONS: CR is both a sensitive and specific marker of reactive and neoplastic mesothelial cells in cytologic cell block preparations and is thus useful in the differential diagnosis of MM and metastatic ACA in malignant effusions. However, CR IHC does not appear to allow definitive identification of SBT in peritoneal washings.

Analysis and classification of proton NMR spectra of lipoprotein fractions from healthy volunteers and patients with cancer or CHD.

Human blood plasma samples from 52 subjects were collected and the very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), low density lipoprotein (LDL) and high density lipoprotein were isolated by serial ultra centrifugation. 600 MHz 1H NMR spectra of the lipoprotein fractions were acquired. The methyl and methylene regions in the spectra of VLDL, LDL and HDL were utilised in further analyses via Kohonen neural networks (KNN) and generative topographic mapping (GTM), two related examples of (unsupervised learning) self-organising feature mapping techniques. Systematic variations in lipoprotein profiles can be substantially visualised through the use of KNN and GTM. The relationship between the sample positions in the Kohonen plot was visualised by surface plots of the corresponding VLDL and HDL cholesterol and VLDL triglyceride contents. The GTM maps of the VLDL and HDL fractions were used to investigate the individual properties of selected samples. A large number of the cancer patients were found clustered in the VLDL GTM map, and GTM map positions of samples in relation to CHD, diabetes and renal failure could be found. Although the study group here considered is heterogeneous in respect to age, sex, type of disease and medications within each defined class, classification of VLDL and HDL data with probabilistic neural network (PNN) was quite successful with respect to the groupings: cancer, CHD, volunteers and other (comprising patients with other diseases). Statistics based on 15 independent sets of PNN calculations gave true positive fractions usually higher than 0.83 and false positive fractions lower than 0.088. Attempts to use the corresponding LDL data and four classes were uniformly poor although some classifications (e.g., volunteer versus CHD) were easily performed.

Quantification of plasma lipids and apolipoproteins by use of proton NMR spectroscopy, multivariate and neural network analysis.

New approaches for quantification of human blood plasma lipids and apolipoproteins are presented. One method is based on multivariate analysis of proton nuclear magnetic resonance spectra of human blood plasma. Although similar approaches have been developed previously, this is the first time principal component analysis (PCA) and partial least squares regression (PLS) have been applied to this particular task. Further, a large proportion of the subjects in this study were cancer patients undergoing treatment, which introduced a new dimension to the quantification of lipoprotein distributions. Calibration models for prediction of lipids and apolipoproteins were constructed by use of PLS, and blind samples were used to test the predictive ability. Comparison of the predicted vs observed data obtained by standard clinical chemical procedures gave good agreement; the correlation coefficient for total plasma triglyceride was 0.99, for total plasma cholesterol 0.98, for LDL cholesterol 0. 97, and for HDL cholesterol 0.88. These results are comparable with those obtained with other methods. The quantitative analysis of 14 components (including total cholesterol and total triglyceride) of human blood plasma was also undertaken using various neural network (NN) analyses of selected portions of the spectra. Conventional fully connected backpropagation neural network topologies were capable of providing excellent predictions for the majority of the variables, confirming and reinforcing literature related to this approach. However HDL triglycerides were poorly predicted, while intermediate-quality results were obtained for the LDL cholesterol, plasma apoA1 and LDL apoB variables. In these instances, applying significantly different neural network algorithms involving either general regression or polynomial neural networks in combination with genetic adaptive components for parameter optimisation made improved predictions.

Hyperosmotic perfusion of the beating rat heart and the role of the Na+/K+/2Cl- co-transporter and the Na+/H+ exchanger.

The aim of the present study was to investigate the role of the Na+/K+/2Cl- co-transporter and the Na+/H+ exchanger on contractile function and electrolyte regulation during hyperosmotic perfusion of the heart. Langendorff perfused rat hearts were subjected to hyperosmolal perfusion in 10-min intervals. Perfusates were made hyperosmotic by adding mannitol to the buffer (370, 450 and 600 mOsmol/kg H2O). Cardiac contractile function was monitored with a balloon in the left ventricle (LV) coupled to a pressure transducer. Cardiac effluent was sampled repeatedly throughout and after hyperosmotic perfusion and analysed for content of Na+, K+, and Cl-. All three hyperosmotic perfusates initially reduced LV developed pressure (LVDP), but for 370 and 450 mOsmol/kg H2O, LVDP recovered to baseline within 4 min of perfusion. With 600 mOsmol/kg H2O, LVDP recovered slowly and was 50% below baseline after 10 min of hyperosmotic perfusion. Inhibition of the Na+/H+ exchanger with 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and 3-methylsulfonyl-4-piperidinobenzoyl-guanidine methanesulfonate (HOE 694) abolished the recovery of LVDP to the 600 mOsmol/kg H2O perfusate, whereas inhibition of the Na+/K+/2Cl- co-transporter had no impact on LVDP. Potassium was taken up by the heart during hyperosmotic perfusion and this uptake was significantly reduced with inhibition of the Na+/H+ exchanger. Intracellular pH was assessed with 31p magnetic resonance spectroscopy and hyperosmolality induced a significant alkalosis that was dependent upon the Na+/H+ exchanger. The rat heart responds to moderate elevations in osmolality with a transient reduction in contractile function, whereas an elevation of 300 mOsmol/kg H2O persistently reduces contractile function. The Na+/H+ exchanger, but not the Na+/K+/2Cl- co-transporter, is of importance in contractile recovery and electrolyte regulation during hyperosmotic perfusion in the rat heart.

Improved convection compensating pulsed field gradient spin-echo and stimulated-echo methods.

The need for convection compensating methods in NMR has been manifested through an increasing number of publications related to the subject over the past few years (J. Magn. Reson. 125, 372 (1997); 132, 13 (1998); 131, 126 (1998); 118, 50 (1996); 133, 379 (1998)). When performing measurements at elevated temperature, small convection currents may give rise to erroneous values of the diffusion coefficient. In work with high resolution NMR spectroscopy, the application of magnetic field gradients also introduces an eddy-current magnetic field which may result in errors in phase and baseline in the FFT-spectra. The eddy current field has been greatly suppressed by the application of bipolar magnetic field gradients. However, when introducing bipolar magnetic field gradients, the pulse sequence is lengthened significantly. This has recently been pointed out as a major drawback because of the loss of coherence and of NMR-signal due to transverse relaxation processes. Here we present modified convection compensating pulsed field gradient double spin echo and double stimulated echo sequences which suppress the eddy-current magnetic field without increasing the duration of the pulse sequences.

Principal component analysis of proton nuclear magnetic resonance spectra of lipoprotein fractions from patients with coronary heart disease and healthy subjects.

Blood plasma was drawn from 12 healthy subjects and 12 patients with coronary heart disease (CHD). The lipoproteins were fractionated by serial ultracentrifugation. The methyl and methylene regions of proton nuclear magnetic resonance (1 H NMR) spectra of the lipoproteins very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) were analysed by principal component analysis (PCA). Grouping patterns in the score plots and the profiles of the principal components revealed several characteristics of the spectra. LDL subparticle size among the CHD group was consistently skewed against smaller, denser subparticles. This feature was independent of the concentration of LDL cholesterol. Analysis of the LDL spectra by soft independent modelling of class analogy (SIMCA) showed that none of the samples from the CHD group could be assigned as healthy subjects (p < 0.05). We also found that the samples from the healthy subjects were associated with a higher concentration of HDL cholesterol and larger VLDL subparticles. The approach presented, in which PCA is used in combination with NMR spectroscopy, might be implemented in clinical studies to give information about lipoprotein subparticle distribution and lipid content.

Subclassifying atypical squamous cells in Thin-Prep cervical cytology correlates with detection of high-risk human papillomavirus DNA.

Recent studies have proposed subclassifying ASCUS into "favor reactive" (ASFR), "not otherwise specified" (ASNOS), and "favor squamous intraepithelial lesion (SIL)" (ASFS). This study explored the reproducibility of these diagnoses with Thin-Prep cytology and their association with high-risk human papillomavirus DNA (HRHPV). Three pathologists and 1 cytotechnologist with 2 to 25 years of experience reviewed 144 Thin-Prep (Cytyc, Boxborough, MA) specimens previously diagnosed as normal, ASFR, ASNOS, ASFS, and SIL. Interobserver reproducibility was computed with the kappa statistic. The original laboratory diagnosis was compared with the presence of HRHPV types. Interobserver reproducibility for a normal or SIL diagnosis was very good (kappa = .68 and .63). Reproducibility for ASFR, ASNOS, and ASFS ranged from poor to fair (kappa = .21, .19, and .32). In a weighted analysis, kappa values for ASFR/ASNOS and ASFS/SIL were .36 and .62, respectively. HRHPV-positivity for preparations originally diagnosed as N, ASFR, ASNOS, ASFS, and SIL were 5.7%, 8.8%, 17.4%, 47.8%, and 54.5%, respectively. The difference in index of HRHPV for either N or ASFR and ASFS or SIL was significant (P < .001). Reproducibility for ASCUS is generally poor, but better reproducibility is obtained by combining ASFS with SIL and, to a lesser degree, ASNOS with ASFR. ASFS and SIL confer a similar index of HRHPV and merit similar management. ASFR may be managed with cytologic follow-up; but this may depend upon the individual laboratory. HPV testing, in conjunction with cytologic and biopsy follow-up, appears useful for estimating the significance of ASCUS subgroups in laboratory practice.

Metabolite composition in breast tumors examined by proton nuclear magnetic resonance spectroscopy.

BACKGROUND: In vivo characterisation of breast tumors using protein (1H) MR spectroscopy relies upon in vitro interpretation of tissue samples. The present study has investigated metabolite composition in extracts from breast tumors and non-involved breast tissue. Multivariate data analysis was used to determinate combinations of metabolites important for differentiation. MATERIALS AND METHODS: Tumor and non-involved breast tissue were obtained from 16 patients undergoing surgical treatment. 1H NMR spectra of perchloric acid tissue extracts were obtained at a BRUKER Avance DRX600 spectrometer. The data was analysed using principal component analysis and probabilistic neural networks. RESULTS: Low levels of glucose and high content of choline compounds were dominant findings in the tumor spectra. Principal component loadings demonstrated this strong association. The spectra were correctly classified using neural network analysis. CONCLUSIONS: Large differences in the metabolite composition of breast tumors and surrounding breast tissues have been documented.

Myxoid synovial sarcoma: an underappreciated morphologic subset.

Focal myxoid change is a well-recognized feature of synovial sarcoma, but the presence of a predominantly myxoid stroma is rare. We describe seven cases of myxoid synovial sarcoma in which marked myxoid change initially obscured the diagnosis, leading to confusion (principally with malignant peripheral nerve sheath tumor). The median age (20 yr) and tumor location (four lower extremity, two upper extremity, and one head and neck region) were similar to those found in typical synovial sarcoma. Histologically, five cases were monophasic spindle cell lesions with a lacy appearance in areas with a prominent Alcian blue-positive myxoid stroma. Each case had foci with more typical features of synovial sarcoma, including a fascicular growth pattern with a variably collagenized stroma, stromal mast cells, a hemangiopericytoma-like vascular pattern, and calcification. Two cases showed small foci of glandular (biphasic) differentiation. Immunohistochemically, all of the seven cases were positive for epithelial membrane antigen, four of six were positive for pan-keratin, three of six were positive for S-100, two of four were positive for CD99, and six of six were negative for desmin. Clinical follow-up in six cases ranged from 8 to 48 months (median, 21 mo). Local recurrence developed in three patients at 9, 20, and 24 months, respectively. In one of these three patients, lung metastases developed at 13 months, and the patient died of disseminated disease at 23 months. In another of the three patients, lung metastases developed at 27 months. Three patients had no evidence of disease at 8, 15, and 15 months. Our data are too limited to indicate any clinical differences between myxoid synovial sarcoma and conventional synovial sarcoma Recognition of this rare histologic variant of synovial sarcoma is important because it can easily be mistaken for other myxoid spindle cell neoplasms, potentially resulting in suboptimal therapy.

Detection of dexamethasone in the cornea and lens by NMR spectroscopy.

BACKGROUND: To study the penetration and metabolism of dexamethasone phosphate in the cornea and lens from rabbit following topical administration. METHODS: After topical administration of 0.1, 1 and 10% dexamethasone phosphate solutions, respectively, the cornea and lens were removed and extracted with either perchloric acid (PCA) or with chloroform/methanol to study the lipophilic and hydrophilic metabolites of the drug. The extracts were analyzed with 1H and 19F NMR spectroscopy. RESULTS: Using 19F NMR spectroscopy, both dexamethasone and dexamethasone phosphate were detected simultaneously in the extract of the cornea and lens obtained from the eyes denuded of the epithelium before the treatment. Using 10 and 1% drug solutions, the signals from dexamethasone were also detectable in the 1H NMR spectra among many endogenous metabolites. CONCLUSION: 1H and 19F NMR spectroscopy was shown to be a useful method in the study of penetration and metabolism of dexamethasone in the eye, particularly because both the lipophilic and hydrophilic metabolites of the drug could be detected simultaneously.

Nuclear magnetic resonance imaging in studies of gravitropism in soil mixtures.

Gravitropic responses of oat coleoptiles were measured in different growth media; humid air, natural soil and artificial soil (glass beads). The oat coleoptiles in soil and glass beads were monitored by NMR imaging, while those in humid air were imaged in darkness with an infrared-sensitive charge-coupled device (CCD) camera. The present study shows for the first time that gravitropic experiments can be performed in artificial soil using NMR imaging as a convenient and suitable recording method. Not only was it possible to follow the gravitropic curvatures in natural soil, but the artificial soil allowed plant images of sufficient spatial and temporal resolution to be recorded. The advantages of using artificial soil in magnetic resonance imaging studies are that the iron content of glass beads is very low compared with natural soil, and that the artificial soil matrix can easily, be standardized with regard to particle size distribution and nutrient content. Two types of glass beads were used, the diameter of the small and the large beads being 300-400 and 420-840 micrometers, respectively. The growth rate of the coleoptiles in soil and in big beads was roughly the same and only slightly lower than in humid air, whereas small beads reduced the growth rate by approx. 16%. The bending rate of the coleoptiles during the gravitropic response was reduced by c. 65% in soil and 75% in bead mixtures relative to bending in air. It should be noted, however, that the maximum curvature of the coleoptile tip was of the same order in all cases, about 35 degrees. This value may represent the largest possible curvature of the organ. The potential of NMR imaging to study, how plant organs penetrate the soil under the influence of gravitropism, mechanical impedance and thigmotropism is also discussed.

Dexamethasone and dexamethasone phosphate detected by 1H and 19F NMR spectroscopy in the aqueous humour.

To apply nuclear magnetic resonance (NMR) spectroscopy to study the penetration of dexamethasone phosphate into the aqueous humour from rabbit following topical administration. After topical administration of 0.1%, 1.0% and 10% dexamethasone phosphate solutions, respectively, samples of aqueous humour were aspirated, freeze-dried, redissolved in deuterium oxide and analyzed by high resolution 1H and 19F NMR spectroscopy. In order to study the lipophilic and hydrophilic metabolites of the drug, samples obtained after application of 1% dexamethasone phosphate were extracted with methanol/chloroform, and then extracted with perchloric acid. In all samples obtained from eyes denuded of the corneal epithelium prior to administration of dexamethasone, signals corresponding to the chemical shifts of the drug were identified in 19F NMR spectra. In the experiments performed with 1% dexamethasone phosphate, both dexamethasone and dexamethasone phosphate were detected in the aqueous humour. Using 10% dexamethasone phosphate solutions, signals from the drug were detected in 1H NMR spectra simultaneously with signals from about twenty other substances present in the aqueous humour. NMR spectroscopy appears to be a valuable method for studying dexamethasone metabolism and penetration into ocular tissues. It provides simultaneous detection of both the drug metabolites and other substances in the sample and might offer a complementary approach to other analytical methods.

Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part I--Clinical implications of penile tissue mechanical properties.

PURPOSE: The least investigated physical determinant of penile rigidity has been penile tissue material properties. The goals in this study (Part I) were to define two penile mechanical parameters, cavernosal expandability X and tunical distensibility VE/VF, determine their magnitudes in humans and develop an analytical expression for penile volume as a function of these two tissue characteristics and intracavernosal pressure. METHODS: Dynamic infusion pharmacocavernosometry was performed in 21 impotent patients (age 43 +/- 19 y) to provide human geometric, hemodynamic and structural data. A mathematically derived model of hemodynamic and structural-dynamic characteristics of penile erection was developed (Parts I, II, III) incorporating penile tissue mechanical qualities. RESULTS: Cavernosal expandability X provided a measure of the ability to approach maximum volume at relatively low intracavernosal pressures. Tunical distensibility VE/VF denoted the maximal erect to flaccid penile volume ratio. The magnitudes of X and VE/VF in the study population were 0.04-0.17 mmHg-1 and 1.7-5.0 respectively. CONCLUSIONS: Enabling penile volume to be derived as a function of tissue mechanical characteristics and pressure, allows for penile rigidity to be expressed (in Part II) as a function of pressure, geometry and tissue qualities.

Relative value and cost-effectiveness of culture and special stains in fine needle aspirates of the lung.

OBJECTIVE: To define the role of microbiologic stains and culture in lung fine needle aspiration (FNA) specimens. STUDY DESIGN: All lung FNA specimens over a nine-year period, with results of both culture and microbiologic stains (Gram's, methenamine silver and acid fast) were reviewed and correlated with clinical information. RESULTS: Sixty-five cases were identified; 13 cases represented clinically significant infections (20%). Gram's stain identified 3 infections and had 1 false positive result, while culture identified 7 infections and had 9 false positive results. However, all false positive cultures represented easily identifiable contaminants, and eight of nine cases had no associated acute inflammation or necrosis. Aspergillus species were detected in four cases by Papanicolaou and silver stain, while culture was positive in only one case. Coccidioides immitis was detected by both Papanicolaou stain and culture in one case. A single case of Mycobacterium tuberculosis was identified by both culture and acid-fast stain. While culture appeared more cost-effective than Gram's stain for identifying bacteria, both Papanicolaou and methenamine silver stain were more cost-effective for identifying fungi. CONCLUSION: In lung FNA specimens, culture and special stains should be restricted to specimens with acute inflammation or necrosis. Gram's stain and fungal culture are insensitive and not cost-effective, and fungi are often identifiable with routine stains.