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BACKGROUND: Laminitis has a considerable impact on the equine industry. Endocrinopathic laminitis is the most common form and affected horses often have hyperinsulinaemia due to an underlying metabolic disorder. OBJECTIVES: The aim of this study was to determine if insulin weakens the structural integrity of digital lamellae and to develop an ex vivo model for the study of hyperinsulinaemia-induced lamellar failure. STUDY DESIGN: Ex vivo experiment. METHODS: Biomechanical testing was used to assess the structural integrity of lamellar explants exposed to either medium alone (control) or medium supplemented with insulin. Lamellar explants comprised of hoof wall, lamellar tissue and distal phalanx were harvested from four adult horses with no evidence of inflammatory disease or pre-existing disease of the digit. Following an equilibration period, explants were incubated in medium or medium supplemented with insulin (2.5 µg/ml) for 8 h prior to biomechanical testing to obtain load (N), stress (MPa), elongation to failure (mm), and Young's modulus (MPa) for each explant. Significant differences were assessed using a mixed linear model with horses as a random factor and control or insulin-treated group as a fixed factor. RESULTS: Lamellar explants incubated in medium supplemented with insulin failed at significantly lower load (P = 0.0001) and lower stress (P = 0.001) and had greater elongation to failure (P = 0.02). MAIN LIMITATIONS: In addition to the ex vivo nature of the study, location-dependent variability in explant structural integrity and variable diffusion of nutrients due to explant size may have been limitations. However, the study design attempted to account for these limitations through random assignment of explants to treatment groups independent of location and by evaluating stress to failure. CONCLUSIONS: Insulin weakens the structural integrity of equine lamellar explants and an ex vivo model for evaluation of hyperinsulinaemia-induced lamellar failure was established. The summary is available in Spanish - see Supporting Information.

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Prepubertal ovariectomy can dramatically inhibit mammary development, but the mechanism of inhibition is not well characterized. Holstein heifers were ovariectomized (OVX) or sham operated but left intact (INT) at d 40 and then sacrificed at d 55, 70, 85, 100, 130, or 160 to provide tissues for histologic analysis of cell proliferation. Our histologic analyses unexpectedly revealed a pronounced effect of ovariectomy on myoepithelial cell development. Myoepithelial cells were identified on the basis of location, morphology, and immunohistochemical staining for alpha-smooth muscle actin (SMA). Vascular smooth muscle staining served as an internal positive control for all immunohistochemical analyses. Mammary tissues from d 40 heifers had an abundance of SMA+ cells associated with the ductal parenchyma. In INT heifers, the frequency of SMA+ cells decreased as development progressed. Only a limited number of isolated SMA+ cells were observed in d 70 to d 160 INT heifers. In OVX heifers, SMA+ cells were abundant, had elongated morphology, and frequently stained more intensively than vascular smooth muscle cells. The intense SMA staining and altered morphology was most prominent in older heifers. Limited analysis of gene expression revealed that maspin, a protease inhibitor expressed by myoepithelial cells, was expressed in parenchyma from both INT and OVX heifers. Our hypothesis is that ovarian secretions stimulate epithelial proliferation, and block myoepithelial differentiation. Myoepithelial cells are known to limit parenchymal cell proliferation. Ovariectomy may thus remove an estrogenic growth stimulus and permit the emergence of inhibitory cell populations that further limit parenchymal expansion. Our observation has important implications for control mechanisms that regulate parenchymal development.

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This paper addresses the issue of automating the multidimensional chromatographic, signature peptide approach to proteomics. Peptides were automatically reduced and alkylated in the autosampler of the instrument. Trypsin digestion of all proteins in the sample was then executed on an immobilized enzyme column and the digest directly transferred to an affinity chromatography column. Although a wide variety of affinity columns may be used, the specific column used in this case was a Ga(III) loaded immobilized metal affinity chromatography (IMAC) column. Ga(III)-IMAC is known to select phosphorylated peptides. Phosphorylated peptides selected by the affinity column from tryptic digests of milk were automatically transferred to a reversed-phase liquid chromatography (RPLC) column. Further fractionation of tryptic peptides on the RPLC column was achieved with linear solvent gradient elution. Effluent from the RPLC column was electrosprayed into a time-of-flight mass spectrometer. The entire process was controlled by software in the liquid chromatograph. With slight modification, it is possible to add multiple columns in parallel at any of the single column positions to further increase throughput. Total analysis time in the tandem column mode of operation was under 2 h.

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This paper describes the effect of various buffers, surfactants, and organic additives commonly encountered in capillary zone electrophoresis and micellar electrokinetic chromatography on the molecular weight determination of peptides by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. Signal-to-noise ratio generally decreased with increasing buffer concentration without affecting mass accuracy, but the type of buffer was also important. Good spectra were obtained with an ammonium acetate buffer up to a concentration of 500 mM without impacting ionization of either peptides or other mobile phase constituents. Ionization of organic additives, such as anionic surfactants, non-ionic surfactants, and cyclodextrins was buffer dependent and presented a problem when the mass of the additive was in the range of the peptide mass. Brij-35, Tween-80, and cyclodextrins all produced prominent spectra of their own in the presence of sodium or potassium containing buffers, but not with ammonium acetate. Cationization of these neutral species with sodium or potassium ions allowed them to acquire a positive charge and produce spectra. In contrast, the ammonium ion appears to be a poor cationizating agent. Ionization of neutral surfactants was suppressed in ammonium acetate without impacting the spectra of peptides. Ammonium acetate buffers containing 30 mM sodium dodecyl phosphate also gave spectra with good signal intensity and no interference from the surfactant. Suppression of peptide ionization in MALDI was a problem when methanol, tetrabutyl amine, or poly(vinyl alcohol) were used with either ammonium acetate, sodium phosphate, and N-(2-hydroxyethyl)piperazine-N-(2-ethansulfonic acid).

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OBJECTIVES: Sensation in the oral cavity and laryngopharynx has long been believed to be crucial for normal swallowing. One illustration of this belief has been intense interest in reconstruction after cancer resection using sensate tissue transfer as a means of improving swallowing function. A contrarian view is that mucosal sensation, by itself, is, in fact, relatively unimportant to swallowing function. STUDY DESIGN: A prospective study was designed to test the hypothesis that normal swallow function can occur with anesthesia of the upper aerodigestive tract mucosa. METHODS: Baseline (sensate) swallowing function of 13 healthy adults was assessed via video endoscopic swallow studies (VESS). Each subject was then topically anesthetized with lidocaine applied to the oral cavity, oropharynx, hypopharynx, and larynx. Swallowing was then reassessed via VESS and compared to the baseline examination to look for differences in function. RESULTS: There was little difference in swallowing ability between sensate and anesthetized states, even though all the subjects felt that their swallowing had been profoundly disrupted after lidocaine was applied. The main difference was a small increase in the time from food administration to swallowing. A few experienced trace aspiration, which was instantly eliminated on subsequent swallows with simple coaching. CONCLUSION: Normal swallowing can occur spontaneously or with simple coaching even with complete anesthesia of the upper aerodigestive tract mucosa. Current beliefs about the value of sensate free flaps and the importance of sensation in swallowing in general may need refinement.

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HYPOTHESIS: The hypothesis that metronidazole can augment the ototoxicity of gentamicin was tested. BACKGROUND: Metronidazole and gentamicin are antibiotics that are used in combination to provide broad-spectrum antimicrobial coverage. It has been observed clinically that an increased ototoxic effect occurs when these agents are used in combination. METHODS: Groups of guinea pigs were given various doses of gentamicin alone, various doses of gentamicin in combination with metronidazole, or metronidazole alone. Auditory damage was determined electrophysiologically by measurement of the compound action potential. Hair cell damage was quantified by immunofluorescent microscopy. RESULTS: Electrophysiologic data revealed an augmented ototoxic effect when metronidazole was given with both a moderate and a high dose of gentamicin. Thresholds (dB SPLp) for the compound action potential (N1) for animals receiving a medium dose of gentamicin alone (50 mg/kg) were approximately 20-dB SPLp. This threshold increased to approximately 50-dB SPLp when metronidazole (35 mg/kg) was administered along with the medium-dose gentamicin. Additionally, animals receiving high-dose gentamicin (75 mg/kg) alone demonstrated increased N1 thresholds from 85 to 95 when metronidazole (35 mg/kg) was added to the gentamicin regimen. This effect was evident histopathologically by increased cochlear hair cell damage. Outer hair cell loss for animals receiving medium-dose gentamicin alone did not differ from that of controls. When metronidazole (35 mg/kg) was combined, however, outer hair cell loss increased to approximately 50%. CONCLUSIONS: These data support the clinical observation of augmented ototoxicity in patients receiving combined gentamicin and metronidazole. Caution should be used when administering these two agents together. Clinicians should consider other antibiotic strategies whenever possible.

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The hypothesis that cisplatin can augment the ototoxicity of gentamicin was tested. Seven groups of 11 guinea pigs each were given a single dose of cisplatin either alone or 14 days before, at the beginning, midway through, or at the end of a course of gentamicin administered daily for 14 days. Blood and perilymph gentamicin and cisplatin concentrations were determined in three of the animals from each group. Auditory damage was determined in the remaining 8 animals electrophysiologically by measuring the compound action potential and alternating-current cochlear potential. Hair cell damage was determined using the surface preparation technique. An augmented ototoxic effect occurred when the cisplatin was given early in the 14-day course of gentamicin and did not occur when it was given at the end of treatment.

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Although aminoglycoside vestibulotoxicity is well established, the question of cisplatin vestibulotoxicity is controversial. The goals of this study were 1. to determine whether cisplatin induces vestibulotoxicity as measured histologically, and 2. to compare the vestibulotoxicity between gentamicin and cisplatin. Guinea pigs' vestibular end-organ hair bundles in control, gentamicin, and cisplatin groups were compared. In the lateral cristae of the cisplatin group, hair bundles decreased 21% on the central apex portion. In the gentamicin group, a slight decrease (17%) of hair bundles on the striola from the utricular maculae was observed, as was severe damage on the entire cristae, especially on the central apex (70%). These results indicate that gentamicin and cisplatin may not influence vestibular function of the otolithic membrane. However, gentamicin may severely damage and cisplatin may slightly damage the crista ampullaris hair bundles.

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A collaborative partnership between physicians and the laboratory is more important than ever. This requires addressing the five major complaints that physicians have regarding the laboratory within the context of six key characteristics of doctors. The complaints concern: timeliness of information, completeness, accessibility, providing information in a suitable form, and making it understandable to time-pressed physicians. Working effectively with physicians to achieve an immaculate image means understanding why they tend toward control, have difficulty with conceptual presentations, and are quick to stereotype. It also means understanding how to capitalize on their tendency to respect expertise and reward it with loyalty. Establishing a favorable image requires creating a perception of cooperative proactivity based on sensitive performance.

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Cisplatin (cis-diamminedichloroplatinum II) is a potent chemotherapeutic agent that is useful in the treatment of a variety of malignancies. Ototoxicity is a well-known adverse side effect of this drug and has been widely described in reports on clinical and animal studies. Few human temporal bone studies, however, have been performed for cisplatin ototoxicity. This report presents four cases of cisplatin ototoxicity in patients from whom temporal bone specimens with minimal post-mortem autolysis were obtained at autopsy. All patients received between 1 and 6 cycles of cisplatin with doses ranging from 100 to 165 mg/M2 per cycle. None of the patients received significant amounts of aminoglycosides or loop diuretics. Histopathologic changes included loss of inner and outer hair cells in the basal turn of the cochlea, degeneration of the stria vascularis, and a significant decrease in spiral ganglion cells predominantly in the upper turns.

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A large political gathering such as the 1984 Republican National Convention provided the ingredients necessary to challenge a community's medical system. A committee consisting of representatives from the city, the county hospital district, the Dallas County Medical Society, and the American Red Cross coordinated their efforts toward developing a comprehensive plan to provide medical support for all aspects of the convention. Provisions to deal with the following potential problems included: 1) the extreme heat; 2) security; 3) massive crowds on the convention floor; 4) the area in which the demonstrators were staying as well as the area in which the demonstrations were to occur; 5) special requirements for visiting dignitaries; and 6) terrorism. Eighty patients were seen in the protest area. Thirty-nine patients were treated by the Red Cross, and 518 patients were seen in the convention center. Ten patients required transportation to the hospital. Organization, coordination, and cooperation of all personnel and appropriate agencies helped ensure a smooth operation.

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Eye movements that accompany a blink have been measured in human subjects by the use of a visual-persistence method. With straight-ahead binocular viewing, each eye typically rotates nasalward and downward 1-2 deg during the closing phase of a blink. These eye movements are more rapid than the lid movements as recorded by high-speed photography. In fact, the eyes have already completed their initial rotation and started back again before the lids are fully closed. With off-center viewing, a blink causes each eye to rotate toward its primary position of regard. Indeed, if the eye is already in that position when the blink starts, the eye moves very little. With eyelids taped open, an eye tracker can be used, and records confirming the visual persistence tracings are obtained. Sequential photography of the cornea in profile reveals that the eye moves inward and back out again during a blink. The amplitude of this retraction is typically less than 1 mm; and its time course, slower than that of the rotational eye movements, parallels the closure and opening of the lids. In normal conditions of viewing there is no evidence of conjugate saccades, or of any large, upward rotation of the eyes (Bell's phenomenon) that was once believed to take place during a blink.

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We present here a technique for modulating contrast in gratings seen in Maxwellian-view or on a projection screen. The method can be used with achromatic or chromatic grating stimuli. It is based on a high frequency oscillatory displacement of the grating image, which in turn produces a smearing of the image on the observer's retina. The waveform of the displacement and its amplitude determine the appearance and contrast of the image produced on the retina.

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Visual suppression accompanying voluntary saccades and eyeblinks was measured for a range of amplitudes of both. Saccade amplitudes varied from 2 to 32 degrees and blink amplitudes varied from a slight movement to a full closure of the eye. In every case, thresholds for detecting full-field luminance decrements were determined with the method of constant stimuli and a two alternative forced choice procedure. Results from three subjects show a monotonic increase in the amount of suppression produced by saccades and blinks of increasing amplitude. Data are discussed with respect to theories about the origin of visual suppression.

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The effect of different ophthalmic vehicles on the disposition of sodium cromoglycate in tears and ocular tissues of the rabbit eye has been studied over 6 h. The vehicles contained sodium cromoglycate, 2% in an aqueous solution, 2 and 4% in an oleaginous formulation of polyethylene and mineral oil (Plastibase 5W), and 4% in an absorption ointment base of 10% hypoallergenic acetylated lanolin (Modulan) in paraffins. The last formulation was superior to all others studied over 6 h in prolonging the retention of sodium cromoglycate in the precorneal area and the conjunctiva. The concentration of sodium cromoglycate in the tears, conjunctiva and cornea 6 h after administration of the acetylated lanolin base equalled or exceeded the concentrations obtained with the aqueous solution 1 h post-instillation.

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