The value of biomedical research training for veterinary anatomic and clinical pathologists

Veterinary pathologists traditionally have been actively engaged in research as principal investigators and as collaborators. Pathologists frequently obtain advanced training in research; however, it appears that in the last 10 years there has been a reversal of a previous trend toward increasing numbers of pathologists obtaining PhD degrees. This has arisen despite an established shortage of veterinarians engaged in research. This article evaluates the benefits of research training for individual pathologists, including a wide spectrum of professional opportunities and additional skill development beyond that usually provided by diagnostic pathology training alone. Various training models are discussed, including combined and sequential diagnostic residency and research degree training as well as the nondegree research fellowship programs more commonly pursued in human medicine. Best-practice recommendations for program infrastructure, mentorship, time management, and a team approach to research and research training are advocated to facilitate the development of successful programs and to encourage a continued emphasis on integrated training for pathologists as both clinical diagnosticians and experimentalists. This article is intended to help prospective and active pathology trainees, their mentors, and educational administrators optimize opportunities to ensure the future vitality of veterinary pathologists, and their contributions, in basic and applied research.

Quantitative analysis of flavonol glycosides in Ginkgo biloba: a comparison of two analytical methods

A comparison of testing methods for constituents of Ginkgo biloba was performed as part of the process for determining which of the many available analytical methods was most appropriate for inclusion in the American Herbal Pharmacopoeia (AHP). Three primary methods were reviewed: those adopted by the European Pharmacopoeia, the National Science Foundation-Institute for Nutraceutical Advancement (NSF-INA) and the United States Pharmacopeia. Methods were compared by evaluating sample preparation and hydrolysis, precision and methods of total flavonol glycoside calculation by two independent laboratories. The AHP adopted the method of NSF-INA for inclusion in the AHP monograph owing to observed superiority of this method in terms of precision, glycoside calculation, ease of sample preparation and chromatographic parameters.

Silicon-29 diffusion-ordered NMR spectroscopy (DOSY) as a tool for studying aqueous silicates

The first use of silicon-29 diffusion-ordered NMR spectroscopy (DOSY) is reported, in a study of the speciation of aqueous silicates.

A space group assignment of ZrP2O7 obtained by 31P solid state NMR

2-D 31P dipolar recoupling magic angle spinning NMR has been used to determine the true symmetry of the low temperature structure of ZrP2O7 for the first time.

Expression of cyclooxygenase-2 in the macula densa of human kidney in hypertension, congestive heart failure, and diabetic nephropathy

Cyclooxygenase-2 (COX-2) is constitutively expressed in the macula densa of several laboratory animal species where it is considered to play a physiologic role in the regulation of basal renal function. Pertubations to normal homeostasis is shown to be associated with the upregulation of COX-2 in the macula densa of rats and dogs. In contrast, COX-2 has not been detected in the macula densa of normal adult human and non-human primate kidneys, suggesting a less prominent role of this isoform in normal renal function in these species. In this study, we characterized COX-2 expression in human kidneys collected from subjects with a clinical history indicative of compromised renal function associated with diabetic nephropathy (DN), hypertension, and congestive heart failure (CHF). COX-2 expression was evaluated by immunohistochemistry using isoform-specific antibodies and in situ hybridization. No COX-2 protein or mRNA was observed in the macula densa of normal kidneys (n= 11), whereas slight to moderate COX-2 expression was present in the macula densa of 7/15 subjects (46%) with DN, 5/11 (46%) subjects with hypertension, and 3/10 subjects (30%) with CHF. These results indicate that COX-2 is variably induced in the macula densa of the human kidney in compromised renal conditions and that COX-2-mediated prostaglandins may be involved in maintaining adequate renal functions in some patients with DN, hypertension, and CHF. This variability may be related to individual clinical status or synthesis of vasodilatory prostaglandins by cyclooxygenase-1 (COX-1).

Cyclooxygenase-2 expression in inflammatory lung lesions of nonhuman primates

Mammalian cells contain two related but unique isoforms of cyclooxygenase (COX-1 and COX-2). COX-1 is expressed constitutively in a majority of tissues and is involved in the production of prostaglandins (PGs) that modulate normal physiologic functions. COX-2 is inducible by various stimuli and is involved in the production of PGs that modulate physiologic events in development, cell growth, and inflammation. With the exception of peribronchial glands and chondrocytes of peribronchial cartilage, COX-2 is not detectable in the normal lung of nonhuman primates. We evaluated COX-2 expression by immunohistochemical methods in the inflammatory lesions of two cynomolgus monkeys (Macaca fascicularis) with acute severe pneumonia. Both monkeys exhibited acute severe bronchopneumonia; histologically, lung lesions were characterized by infiltration of large numbers of neutrophils and fewer macrophages, mild bronchial epithelial hyperplasia, and slight type-2 pneumocyte hyperplasia. In both monkeys, mild to marked COX-2 immunoreactivity was detected within the cytoplasm of macrophages, bronchial epithelial cells, type-2 pneumocytes, and endothelial cells of blood vessels. No COX-2 immunoreactivity was detectable in the neutrophils that constituted >90% of the inflammatory cells. These observations suggest that in acute inflammatory lung lesions in nonhuman primates 1) COX-2 is induced in the bronchial and alveolar epithelial cells, 2) macrophages are the primary inflammatory cells that exhibit COX-2, and 3) neutrophils do not express COX-2.

Expression of cyclooxygenase-2 in transitional cell carcinoma of the urinary bladder in dogs

OBJECTIVE

To evaluate expression of cyclooxygenase (COX)-1 and COX-2 in the urinary bladder epithelium of clinically normal dogs and in transitional cell carcinoma cells of dogs.

ANIMALS

21 dogs with transitional cell carcinoma of the urinary bladder and 8 dogs with clinically normal urinary bladders.

PROCEDURE

COX-1 and COX-2 were evaluated by use of isoform-specific antibodies with standard immunohistochemical methods.

RESULT

COX-1, but not COX-2, was constitutively expressed in normal urinary bladder epithelium; however, COX-2 was expressed in neoplastic epithelium in primary tumors and in metastatic lesions of all 21 dogs and in new proliferating blood vessels in 3 dogs. Also, COX-1 was expressed in the neoplastic cells.

CONCLUSIONS AND CLINICAL RELEVANCE

Lack of expression of COX-2 in normal bladder epithelium and its substantial expression in transitional cell carcinoma cells suggest that this isoform may be involved in tumor cell growth. Inhibition of COX-2 is a likely mechanism of the antineoplastic effects of non steroidal antiinflammatory drugs.

Carbon-13 and fluorine-19 NMR spectroscopy of the supramolecular solid p-tert-butylcalix(4)arene.alpha,alpha,alpha-trifluorotoluene

The supramolecular 1:1 host-guest inclusion compound, p-tert-butylcalix[4]arene x alpha,alpha,alpha-trifluorotoluene, 1, is characterized by 19F and 13C solid-state NMR spectroscopy. Whereas the 13C NMR spectra are easily interpreted in the context of earlier work on similar host-guest compounds, the 15F NMR spectra of solid 1 are, initially, more difficult to understand. The 19F[1H] NMR spectrum obtained under cross-polarization and magic-angle spinning conditions shows a single isotropic resonance with a significant spinning sideband manifold. The static 19F[1H] CP NMR spectrum consists of a powder pattern dominated by the contributions of the anisotropic chemical shift and the homonuclear dipolar interactions. The 19F MREV-8 experiment, which minimizes the 19F-19F dipolar contribution, helps to identify the chemical shift contribution as an axial lineshape. The full static 19F[1H] CP NMR spectrum is analysed using subspectral analysis and subsequently simulated as a function of the 19F-19F internuclear distance (D(FF) = 2.25 +/- 0.01 A) of the rapidly rotating CF3 group without including contributions from additional libration motions and the anisotropy in the scalar tensor. The shielding span is found to be 56 ppm. The width of the centerband in the 19F[1H] sample-spinning CP NMR spectrum is very sensitive to the angle between the rotor and the magnetic field. Compound 1 is thus an attractive standard for setting the magic angle for NMR probes containing a fluorine channel with a proton-decoupling facility.

Sulfathiazole polymorphism studied by magic-angle spinning NMR

The literature on sulfathiazole polymorphs has many confusions and inconsistencies. These are largely resolved by the distinctive appearance of (13)C magic-angle spinning NMR spectra, which immediately show the number of molecules in the crystallographic asymmetric unit. The spectra presented include those of a newly-recognized form. The assignments of the spectra are established and discussed in relation to such factors as electronic structure of the aromatic ring, second-order quadrupolar effects originating from the nitrogen nuclei, and hydrogen bonding. The results are compared to literature information on the crystal structures. When the amino group acts as a hydrogen bond acceptor, there is a shielding effect on C-4 to the extent of ca. 8 ppm (which should be compared to a further shielding by ca. 10 ppm for sulfathiazole sulfate). The fact that the spectrum of form III is similar to the sum of those of forms IV and V is rationalized in relation to the crystal structures. Some surprising variability of spectra with temperature and with specific sample is reported.

6Li and 7li solid-state NMR spectroscopy of nitrogen ceramic phases

Two nitrogen ceramic phases, the oxynitride LiSiON and the nitride LiSi2N3, have been studied by 6Li and 7Li NMR. Magic angle spinning (MAS) NMR experiments have been carried out at two magnetic field strengths (7.05 and 14.1 T). The spectra give evidence of the relative effects of the quadrupolar and chemical shift interactions. The electric field gradient tensor of both phases has been determined accurately by iterative fitting of the 6Li and 7Li MAS NMR line shapes at the two magnetic field strengths. Due to the fact that for 7Li the quadrupolar interaction is much larger than the chemical shift interaction, it is shown that neither the small chemical shift anisotropy nor the relative orientation of the two interaction tensors can be determined accurately by 7Li MAS NMR. For 6Li, the two interactions are comparable and the value of these parameters obtained from the fits of the 6Li experimental MAS line shapes are therefore much more reliable.

Analysis of cross-polarization dynamics between two abundant nuclei, (19)F and (1)H, based on spin thermodynamics theory

The phenomenological theory of spin thermodynamics based on the spin temperature hypothesis was employed to describe the cross-polarization (CP) dynamics between two abundant nuclei, (19)F and (1)H, when the number of fluorine atoms is not substantially less than the number of hydrogens. The influence of T(1rho)'s of both nuclei and the relative magnitude (heat capacity) of the two spin baths must be incorporated explicitly into the analysis in order to derive values for the parameters involved in the CP dynamics. Numerical calculations were performed to clarify the difference in the evolution of magnetization in variable contact time CP experiments between the (1)H --> (13)C and (1)H --> (19)F cases. A new type of CP-drain experiment was developed for observing the residual (1)H magnetization after (1)H --> (19)F CP. (19)F direct polarization magic-angle spinning (MAS), (1)H --> (19)F CP, and (1)H --> (19)F CP-drain MAS NMR spectra have been measured for a fluorinated polyimide, 6FDA/ODA. The CP dynamics between (1)H and (19)F for the polyimide were analyzed on the basis of the spin thermodynamics theory. The constant for polarization transfer (T(HF)) was determined by the analysis using the effective CP parameters, which were directly obtained from the CP and CP-drain experiments, together with independently measured values of T(H)(1rho) and T(F)(1rho). Copyright 1999 Academic Press.

Fluorine-19 solid-state NMR magic-angle-turning experiments using multiple-pulse homonuclear decoupling

For compounds giving "crowded" 1-dimensional magic-angle-spinning spectra, information about the local atomic environment in the form of the chemical shift anisotropy (CSA) is sacrificed for high resolution of the less informative isotropic chemical shift. Magic-angle-turning (MAT) NMR pulse sequences preserve the CSA information by correlating it to the isotropic chemical shift in a 2-dimensional experiment. For low natural abundance nuclei such as 13C and 15N and under 1H heteronuclear dipolar decoupling conditions, the dominant NMR interaction is the chemical shift. For abundant nuclei such as 1H, 19F, and 31P, the homonuclear dipolar interaction becomes a significant contribution to the observed linewidth in both F1 and F2 dimensions. We incorporate MREV8 homonuclear multiple-pulse decoupling sequences into the MAT experiment to give a multiple-pulse MAT (MP-MAT) experiment in which the homonuclear dipolar interaction is suppressed while maintaining the chemical shift information. Extensive use of computer simulation using GAMMA has guided the pulse sequence development. In particular, we show how the MREV8 pulses can be incorporated into a quadrature-detected sequence such as MAT. The MP-MAT technique is demonstrated for a model two-site system containing a mixture of silver trifluoroacetate and calcium difluoride. The resolution in the isotropic evolution dimension is improved by faster sample spinning, shorter MREV8 cycle times in the evolution dimension, and modifications of the MAT component of the pulse sequence. Copyright 1999 Academic Press.

A method for analysing proton NMR relaxation data from motionally heterogenous polymer systems

Historically, the results of studies of the motional processes present in polymers above the glass transition temperature (Tg) by proton NMR spin-lattice relaxation in either the laboratory or rotating frames (T1 or T1p) have shown poor agreement with the results from similar studies carried out using other techniques such as dielectric or mechanical relaxation. We believe that this is mainly because of the complication of the NMR results due to magnetisation transport, either by spin diffusion or by bulk diffusion of the polymer. We suggest a novel approach to the analysis of proton NMR relaxation data from a motionally heterogeneous polymer, and show that the results of such an analysis are intrinsically reasonable and of the form expected for dielectric or mechanical relaxation.

Parameters and symbols for use in nuclear magnetic resonance (IUPAC recommendations 1997)

NMR is now frequently the technique of choice for the determination of chemical structure in solution. Its uses also span structure in solids and mobility at the molecular level in all phases. The research literature in the subject is vast and ever-increasing. Unfortunately, many articles do not contain sufficient information for experiments to be repeated elsewhere, and there are many variations in the usage of symbols for the same physical quantity. It is the aim of the present recommendations to provide simple check-lists that will enable such problems to be minimised in a way that is consistent with general IUPAC formulation. The area of medical NMR and imaging is not specifically addressed in these recommendations, which are principally aimed at the mainstream use of NMR by chemists (of all sub-disciplines) and by many physicists, biologists, materials scientists and geologists etc. working with NMR. The document presents recommended notation for use in journal publications involving a significant contribution of nuclear magnetic resonance (NMR) spectroscopy. The recommendations are in two parts: (1) Experimental parameters which should be listed so that the work in question can be repeated elsewhere. (2) A list of symbols (using Roman or Greek characters) to be used for quantities relevant to NMR.

Solid-state 19F NMR investigation of poly(vinylidene fluoride) with high-power proton decoupling

The use of high-power proton decoupling has enabled highly-resolved spectra of fluorine polymers to be recorded, as is exemplified herein for semicrystalline poly(vinylidene fluoride) (PVDF). By means of high MAS speeds (up to 17 kHz), the spinning sidebands are removed from the whole of the relevant chemical shift range. For spectra of the crystalline regions of the polymer, the high-power decoupling is necessary, though its effect is not large. Various relaxation techniques have been used to examine the semicrystallinity and the polymorphism of PVDF, with special pulse sequences used to discriminate between the various domains. Different chemical shifts have been observed for the signals of the amorphous and crystalline phases. Those of the more immobile parts cover a substantial range.

Effect of 1H-decoupling in two-dimensional multiple-quantum MAS NMR spectroscopy of 23Na in a hydrous layered silicate

In order to check the efficiency of high-power 1H decoupling when used with the two-dimensional multiple-quantum MAS method recently proposed to obtain isotropic spectra from quadrupolar nuclei, we applied this new technique to 23Na NMR for a hydrous layered silicate compound, makatite, with and without 1H decoupling. A remarkable improvement of the spectral resolution in the isotropic dimension was observed by the decoupling, showing that it is effective in the 2D MQ-MAS method and suggesting that proton decoupling should be generally applied in 23Na experiments concerning these kinds of compound.

Studies of an Isolated 15 N-15 N Spin Pair. Off-Angle Fast-Sample-Spinning NMR and Self-Consistent-Field Calculations for Diazo Systems

An off-magic-angle spinning study of the nonassociated molecular solid, doubly 15 N-labeled 5-methyl-2-diazobenzenesulphonic acid hydrochloride (I ) is reported. The validity of the off-magic-angle spinning approach under fast-spinning conditions is verified by average Hamiltonian theory. Ab initio SCF calculations were performed on the simpler molecule, C6 H5 N2 + , to provide the shielding parameters, the dipolar coupling between the two nitrogen nuclei, and the electric field gradient existing at both the alpha-nitrogen and beta-nitrogen sites. The calculated values are in good agreement with the shielding and effective dipolar coupling data elucidated in the present investigation, and with a previous study of the two singly 15 N-labeled isotopomers in which information concerning the electric field gradient at the alpha and beta sites was deduced.

Respiratory and pharyngo-esophageal iridovirus infection in a gopher tortoise (Gopherus polyphemus)

A free-living adult male gopher tortoise (Gopherus polyphemus) was found on Sanibel Island, Florida (USA), on 18 February 1992 with signs of upper respiratory disease. On necropsy after euthanasia on 27 February 1992, severe, extensive necrotizing ulcerative tracheitis, multifocal necrotizing pneumonia, and multifocal necrotizing ulcerative pharyngitis and esophagitis were observed. Large ovoid to round intracytoplasmic basophilic inclusions, which appeared to displace the nucleus to the cell periphery, occurred within degenerate and necrotic epithelial cells of the above tissues. On transmission electron microscopy of formalin-fixed trachea and lung, intracytoplasmic viral particles were observed within necrotic cells in the tracheal lumen and epithelial cells of the lung. Most infected cells also had a roughly spherical granular cytoplasmic inclusion that contained clusters of viral particles. Viral particles had an electron dense spherical to icosahedral core surrounded by a less electron dense icosahedral capsid. Mature extracellular virions were surrounded by an envelope and were 150 to 220 nm in diameter. Virions and cytoplasmic inclusions were morphologically similar to those of the Family Iridoviridae.

Proton fluorine wideline separation experiments on poly (vinylidene difluoride)

Two-dimensional heteronuclear proton-fluorine correlation solid-state spectroscopy is demonstrated on a sample of poly (vinylidene difluoride) (PVDF). This allows the correlation of structural information contained in the fluorine chemical shift in one dimension with information on mobility from proton wideline spectra in the second dimension. The effect of the heteronuclear fluorine-proton dipolar coupling on the proton linewidth is investigated separately. The incorporation of magnetization filters into the preparation period enables one to measure the wideline separation (WISE) spectra for the amorphous or the crystalline parts of the sample separately.

1H, 29Si and 1H, 23Na heteronuclear shift correlation in octosilicate via cross-polarisation

Solid-state magic-angle spinning was used to study octosilicate, a layered sodium polysilicate hydrate. Conventional one-dimensional NMR spectra detect two distinct proton and silicon sites and a single sodium species. Heteronuclear shift correlation experiments have shown that only one type of proton is involved in efficient cross-polarisation to all the silicon and sodium sites. Such selectivity could be caused by a favourable position for, and suitable rigidity of, this strongly hydrogen-bonded proton. The latter requirement can be used to propose a simple model of the interlayer space in octosilicate.

Clinical and clinical laboratory correlates in sea otters dying unexpectedly in rehabilitation centers following the Exxon Valdez oil spill

Following the Exxon Valdez oil spill, 347 oiled sea otters (Enhydra lutris) were treated in rehabilitation centers. Of these, 116 died, 94 within 10 days of presentation. Clinical records of 21 otters dying during the first 10 days of rehabilitation were reviewed to define the laboratory abnormalities and clinical syndromes associated with these unexpected deaths. The most common terminal syndrome was shock characterized by hypothermia, lethargy, and often hemorrhagic diarrhea. In heavily and moderately oiled otters, shock developed within 48 hours of initial presentation, whereas in lightly oiled otters shock generally occurred during the second week of captivity. Accompanying laboratory abnormalities included leukopenia with increased numbers of immature neutrophils (degenerative left shift), lymphopenia, anemia, azotemia (primarily prerenal), hyperkalemia, hypoproteinemia/hypoalbuminemia, elevations of serum transaminases, and hypoglycemia. Shock associated with hemorrhagic diarrhea probably occurred either as a direct primary effect of oiling or as an indirect effect secondary to confinement and handling in the rehabilitation centers. Lightly oiled otters were less likely to die from shock than were heavily oiled otters (22% vs. 72%, respectively). Heavily oiled otters developed shock more rapidly and had greater numbers of laboratory abnormalities, suggesting that exposure to oil was an important contributing factor.

The diazo group as an example of an isolated 15N-14N nuclear spin pair: a static and variable spinning frequency investigation

The 15N-14N heteronuclear spin pair present in the polycrystalline compound 5-methyl-2-diazobenzenesulphonic acid hydrochloride singly labelled with 15N at either the alpha- or the beta-position is investigated by solid-state nuclear magnetic resonance. The 15N spectrum is obtained both under static and spinning conditions. Unusually well resolved fine structure is observed in both cases and, in particular, the static spectra allow a direct and straightforward measurement of the 15N-14N internuclear dipolar coupling in addition to values of the principal components of the shielding tensors for 15N labelling (at either the alpha- or the beta-positions of the diazo moiety) and their orientation relative to a molecular frame. We also present a preliminary theoretical discussion concerning the origin of the observed spinning frequency dependence of the sideband fine structure.

Quadrupole effects of spin-3/2 nuclei on the solid-state magic-angle spinning nuclear magnetic resonance spectra of spin-1/2 nuclei. Deviations from first-order theory and implications concerning the sign of the indirect coupling constant

The effect of the interaction between spin-3/2 and spin-1/2 nuclei on solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra of the latter is studied in cases where deviations from first-order theory are expected. A comparison is made between the exact and first-order perturbation approaches. Both dipolar and indirect (iso- and anisotropic) coupling interactions are considered. Implications regarding 13C,35,37Cl, 31P,63,65Cu and 119Sn,35,37Cl cases are discussed. It is shown that in the latter two cases the sign of the indirect coupling constant J can be derived.

Histopathologic lesions in sea otters exposed to crude oil

Following the Exxon Valdez oil spill in Prince William Sound, Alaska, sea otters (Enhydra lutris) that appeared to be contaminated with oil, that were in danger of becoming contaminated, or that were behaving abnormally were captured and taken to rehabilitation centers. Exposure to oil was assessed by visual examination when otters arrived at the centers. Degree of oil exposure was graded according to the following criteria: oil covering greater than 60% of the body--heavily contaminated; oil covering 30-60% of the body--moderately contaminated; oil covering less than 30% of the body or light sheen on fur--lightly contaminated. If there was no oil visible, otters were considered uncontaminated. Tissues from 51 oil-contaminated sea otters (14 males, 37 females) and from six uncontaminated sea otters (three males, three females) that died in rehabilitation centers were examined histologically. Among oil-contaminated sea otters, 19/46 had interstitial pulmonary emphysema, 13/40 had gastric erosion and hemorrhage, 11/47 had centrilobular hepatic necrosis, 14/47 had periportal to diffuse hepatic lipidosis, and 10/42 had renal tubular lipidosis. Of the uncontaminated sea otters, 1/6 had gastric erosion and hemorrhage and 1/6 had diffuse hepatic lipidosis. Histologic examinations were performed on tissues from five sea otters (three males, two females) found dead with external oil present 15 to 16 days after the spill. Periportal hepatic lipidosis and renal tubular lipidosis were found in 3/5, and interstitial pulmonary emphysema was found in 1/5. Tissues from six apparently normal sea otters (four males, two females) collected from an area not affected by an oil spill were examined histologically, and none of these lesions were found. We conclude that interstitial pulmonary emphysema, centrilobular hepatic necrosis, and hepatic and renal lipidosis of sea otters were associated with exposure to crude oil. Gastric erosion and hemorrhage may have been associated with stress of captivity and/or oil exposure.

Dental amalgam: success or failure?

A review of recent literature suggests that reasons for amalgam failure can generally be identified and avoided. These include: retentive failure, marginal breakdown, fracture of the tooth or restoration, reasons for sensitivity, poor surface characteristics, and contributions to periodontal disease. Materials themselves are least often the source of problems; rather, most of the failures can be attributed to lack of attention to detail in cavity preparation and handling of the materials.

A histomorphologic and immunohistochemical study of chordoma in twenty ferrets (Mustela putorius furo)

The histomorphologic and immunohistochemical features of chordoma in 20 ferrets were evaluated. The mean age was 3.4 years, and, in the cases for which sex was known, females (n = 10) outnumbered males (n = 5) two to one. All 20 tumors occurred on the tip of the tail. Nineteen of 20 tumors (95%) were composed of three tissue components, often arranged concentrically with lobules of physaliferous cells at the periphery, trabecular bone in the center, and cartilage in between. The bone often contained marrow and hematopoietic cells. One tumor lacked chondromatous or osseous tissue. Immunohistochemical results were consistent with previous studies of chordoma. All 20 tumors (100%) were positive for keratin and vimentin intermediate filaments; 15 (75%) were positive for S-100 protein; and 17 (85%) were positive for neuron specific enolase. This neoplasm shares morphologic and immunohistochemical features with "classic," as well as chondroid chordoma, of human beings, making it a potential animal model.

Effects of methanol vapor on human neurobehavioral measures

Methanol could become an important motor fuel. The objective of this exploratory study was to provide preliminary information about whether or not acute exposure to methanol at 250 mg/m3 for 75 minutes would have adverse effects on human neurobehavioral functions important in everyday life. This concentration level was selected because it is at the upper limit of the traffic scenario estimates provided by the U.S. Environmental Protection Agency (EPA)2 (86 to 240 mg/m3), but is below the maximum concentrations for eight-hour average exposures currently recommended by the National Institute of Occupational Safety and Health (NIOSH) and the American Conference of Government and Industrial Hygienists (ACGIH) (260 mg/m3). Although traffic scenario exposure estimates suggest that such high levels of exposure last less than 15 minutes, we used a 75-minute exposure to increase the probability of identifying dependent measures that should be studied in more detail in a future confirmatory study. Twelve healthy young men, each serving as his own control, participated in two sham exposures and two methanol exposures under counterbalanced, double-blind control conditions. Because methanol is present in many foods, and because high preexposure levels of methanol or formate might obscure exposure effects, subjects were required to strictly limit their diets for 12 hours before each experimental session. The following endpoints were examined before, during, and after exposure to methanol and sham vapors: blood and urinary methanol; plasma formate; oral temperature; blood pressure; subjective mood, alertness, fatigue, workload, and symptom scales; spectral analysis of the electroencephalogram; visual- and auditory-event-related potentials; contingent negative variation; respiration; cardiac interbeat interval; Symbol Digit substitution task; three-choice reaction time; Stroop color-word test; simple reaction time; visual function; critical flicker fusion frequency; hand steadiness; visual search task; Gamberale reaction time task; visual tracking task; Sternberg memory task; interval production task; and speeded addition task. Two dual tasks were also included in the task batteries. These endpoints were selected from those indicated in the literature to be sensitive to solvents, and from those that are widely used in other neurobehavioral test batteries to identify the effects of environmental pollutants. Because the number of endpoints examined was large and the number of subjects was small, procedures designed to reduce the number of statistical tests performed were used. Mean methanol concentration in the exposure room during methanol exposures was 249 mg/m3 (SD +/- 7 mg/m3). Exposure produced significant increases in blood and urine methanol concentration. As expected, no changes in plasma formate were observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronic upper respiratory tract disease of free-ranging desert tortoises (Xerobates agassizii)

Seventeen desert tortoises, Xerobates agassizii, with upper respiratory tract disease were examined; thirteen were euthanatized for necropsy. Four normal control desert tortoises from a clinically healthy population were similarly evaluated. Hemoglobin and phosphorus values were significantly (P less than or equal to 0.05) lower and serum sodium, urea, SGOT, and cholesterol values were significantly higher in ill tortoises compared to controls. No significant differences in concentrations of serum or liver vitamins A and E were found between the two groups. While no significant differences were found for concentrations of lead, copper, cadmium, and selenium, the livers of ill tortoises had higher concentrations of mercury and iron. Lesions were found consistently in the upper respiratory tract (URT) of ill tortoises. In all ill tortoises dense infiltrates of lymphocytes and histiocytes obscured the mucosal epithelium and underlying glands. The mucosal epithelium was variably dysplastic, hyperplastic, and occasionally ulcerated. Electron microscopic studies revealed small (350 to 900 nm), pleomorphic organisms resembling Mycoplasma sp., in close association with the surface epithelium of the URT of ill tortoises. Pasteurella testudinis was cultured from the nasal cavity of all ill tortoises and one of four control tortoises. A Mycoplasma sp. was cultured from the nasal passageways of four ill tortoises and was ultrastructurally similar to the pleomorphic organism present on the mucosa in tissue section.

Toxoplasmosis in Atlantic bottle-nosed dolphins (Tursiops truncatus)

A female Atlantic bottle-nosed dolphin (Tursiops truncatus) and her calf were found beached on Picnic Island in Tampa Bay, Florida, USA. Despite therapy the animals died. Necropsy revealed severe pneumonia and lymphadenopathy in the mother and the calf, gastric ulcers and infection with the stomach digenean Braunina cordiformis in the mother, and a large, pale liver in the calf. Toxoplasma gondii was identified by light and electron microscopy and by immunohistochemistry in tissues of both animals. Toxoplasma gondii was associated with interstitial pneumonia, necrotizing adrenalitis, and cardiac myonecrosis in the mother and with lymphoid necrosis in both dolphins. The source of infection and the relationship to the recent dolphin beachings along the eastern seacoast of North America are unknown. This is the first report of toxoplasmosis in cetaceans.

Eosinophilic meningoencephalitis due to Angiostrongylus cantonensis as the cause of death in captive non-human primates

Fatal eosinophilic meningoencephalitis due to Angiostrongylus cantonensis is reported in captive non-human primates. A howler monkey (Alouatta caraya) at the Audubon Park and Zoological Gardens, New Orleans, LA, died 21 days after initial clinical symptoms. A white-handed gibbon (Hylobates lar) died at the Ardastra Gardens and Zoo, Nassau, Bahamas, 17 days after onset of symptoms. Both had access to free-ranging gastropods within the zoos. These are the first reported cases of natural infection by A. cantonensis in non-human primates in the western hemisphere.

Toxicology studies of a chemical mixture of 25 groundwater contaminants. I. Chemistry development

As part of an effort to evaluate the toxicology of a chemically defined mixture of 25 frequently detected groundwater contaminants, we report here the formulation and analytical chemistry of this mixture. Many problems were anticipated, including limitation of solubility, chemical interactions, and extreme volatility in the aqueous solution of 25 chemicals. The final technically achievable stock solution was prepared based on EPA survey concentrations of these chemicals in groundwater around hazardous waste disposal sites, their toxicity information, and solubility of the individual compounds in the matrix of the aqueous solution of these 25 chemicals. Because the anticipated animal studies were to be conducted at various laboratories, for ease of handling and maximum stability, the stock solution was stored or shipped as two substock solutions: an organic substock with 18 neat organic chemicals in a glass vial sealed with minimum headspace and an aqueous substock solution with 6 metals of various salt forms and phenol. The concentrations of the solutions were such that direct mixing of the organic and aqueous substocks produced the desired high dose level for the animal experiments. Analyses of all 25 chemicals in the drinking water mixture required six different chromatographic and spectroscopic methods. Some loss of organic volatiles during mixing of the substocks and during the first 24 hr following preparation did occur. However, the concentrations of acetone, phenol, and all the metals remained constant during preparation. Solutions held under simulated animal cage conditions for 96 hr showed losses of the organic volatiles; the majority of which occurred within the first 24 hr. This study shows that it is possible to conduct animal experiments on an aqueous mixture containing 25 groundwater contaminants. Furthermore, a reasonable estimate of intake of individual chemicals can be achieved provided that dosing solutions are prepared fresh at frequent intervals (e.g., 48 to 72 hr) and that comprehensive analyses are carried out.

A comparative study of the strength of aluminous porcelain and all-ceramic crowns

This study compared the breaking strengths of all-ceramic crowns constructed with aluminous porcelain, the Cerestore system, and the Dicor system on an anterior tooth preparation. Fifteen crowns from each group were constructed to comparable dimensions on dies from the same master die. Ten crowns from the same group were cemented on the master die and loaded until catastrophic failure. Five crowns from each group were embedded and sectioned to examine internal adaptation. No significant difference was found between the load necessary to produce failure in the aluminous porcelain and Dicor crowns and the load needed to initiate crack formation in the Cerestore crowns. However, seven of the 10 Cerestore crowns showed a two-phase failure pattern; the difference between crack initiation and catastrophic failure was significant. Within the limitation of this study, neither the Cerestore (high alumina core) nor the Dicor (castable glass-ceramic) produced an all-ceramic crown superior to the current aluminous porcelain crown.