[A sudden onset of groin pain]. / Plotselinge pijn in de lies.

We describe an 11-year-old boy with sudden onset of right groin pain which occurred during soccer. He was diagnosed with an avulsion fracture of the lesser trochanter, a hyperextension and rotation trauma due to traction on the iliopsoas tendon. The treatment was conservative and full function returned.

Wiring taste receptor cells to the central gustatory system.

Taste receptor cells in the tongue are epithelial in nature and turnover frequently. Taste receptor cell-associated neurons carrying bitter, sweet, or sour signals never turnover and are hardwired to specific gustatory centers in the brain. How can ever-changing bitter or sweet receptors find never-changing neurons that must match the specificity of the signal? This article reviews a recent paper published in Nature (Lee, MacPherson, Parada, Zuker, & Ryba, , 548:330-333) that identified two molecules belonging to the semaphorin axon guidance family of molecules (SEMA3A and SEMA7A) that help maintain the "labeled line principle" between peripheral bitter or sweet receptors and their respective central projection area in the gustatory center.

The natural course of chronic exertional compartment syndrome of the lower leg.

PURPOSE: The aim of this study was to investigate the natural course of chronic exertional compartment syndrome (CECS) in the lower leg. METHODS: Twelve military men [mean age 30 (SD 4)] diagnosed with CECS after intracompartmental pressure (ICP) measurements immediately post-exercise in 21 legs, who did not undergo a fasciotomy, were reviewed and participated in a repeat pressure measurement after a mean time of 50 months (SD 15). RESULTS: Sixteen of 21 legs still showed an ICP of 35 mm Hg or more (the cut-off point) at the second visit. All twelve patients still had typical complaints. Mean ICP at index measurement was 58 (SD 15) mm Hg. At the second visit, it was 51 (SD 15) mm Hg. Six patients chose to undergo a subcutaneous fasciotomy, and these six patients all benefited in the short term. CONCLUSION: The natural course of CECS seems to be persistent symptoms over time. LEVEL OF EVIDENCE: Case series with no comparative group, Level IV.

A clinical decision model identifies patients at risk for delayed diagnosed injuries after high-energy trauma.

OBJECTIVE: Tertiary trauma survey is widely implemented in trauma care to identify all injuries in trauma patients. However, various studies consistently show that some trauma patients have missed injuries. In this study, we developed a clinical decision model to identify patients who are at risk for delayed diagnosed injuries. METHODS: During a period of 18 months, we collected the medical records of all the adult patients who presented after a high-energy trauma at the emergency department of a Dutch trauma centre. The type of trauma, patient characteristics, the radiology studies performed, Glasgow Coma Scale, Revised Trauma Score, and Injury Severity Score (ISS) were registered. We thoroughly screened all medical records for delayed diagnosed injuries. Stepwise logistic regression analysis was used to identify the variables associated with the outcome delayed diagnosed injuries and to develop a clinical prediction model. RESULTS: We included 475 patients. Thirteen (2.7%) patients with delayed diagnosed injuries were identified. Stepwise logistic regression analysis revealed several models with the ISS, ICU admittance, and CT-head as predictive variables. The model we proposed with the ISS could identify patients who are at a risk for delayed diagnosed injuries with a sensitivity of 92.3% and a specificity of 86.4%. CONCLUSION: Our newly developed clinical decision model can identify patients who are at a risk for delayed diagnosed injuries and who should undergo an intensified search for potential unidentified injuries.

[Waveboard-related injuries. Greater protection is advised]. / Letsels bij 'waveboarden'. Aanbeveling om meer bescherming te dragen.

OBJECTIVE: Waveboarding, a type of skateboarding, is a new craze among children. The aim of this study is to describe how many children visit the emergency department as a consequence of waveboarding and the types of injury they have. DESIGN: Retrospective, descriptive. METHOD: All records of children aged 5 to 15 years who had visited the emergency department of the Medical Center Alkmaar in the period March to May 2010 were examined. If a case of waveboard-related injury was found then the type of injury was noted. For all of the injuries a phone call was made to try to find out if protective gear had been worn. RESULTS: A total of 1418 records from 2010 were investigated. In 132 cases, a waveboard-related injury was found. Contusion was found in 31% of cases and a fracture in 64% of cases. The 2 most frequently occurring sites of injury were the forearm and wrist (53%) and the elbow (14%). In 3% of the waveboard-related injuries the child concerned had worn any protective gear. CONCLUSION: Children who visited the emergency department due to waveboard-related injuries mainly had injuries to the wrists, forearm and elbow. Only 3% of the children wore protective gear when waveboarding. As effective protection against accident-related injuries exists for skaters, the wearing of protective gear during waveboarding can be expected to lead to a reduced number of injuries.

Sodium/glucose cotransporter-1, sweet receptor, and disaccharidase expression in the intestine of the domestic dog and cat: two species of different dietary habit.

The domestic cat (Felis catus), a carnivore, naturally eats a very low carbohydrate diet. In contrast, the dog (Canis familiaris), a carno-omnivore, has a varied diet. This study was performed to determine the expression of the intestinal brush border membrane sodium/glucose cotransporter, SGLT1, sweet receptor, T1R2/T1R3, and disaccharidases in these species adapted to contrasting diets. The expression (this includes function) of SGLT1, sucrase, maltase and lactase were determined using purified brush border membrane vesicles and by quantitative immunohistochemistry of fixed tissues. The pattern of expression of subunits of the sweet receptor T1R2 and T1R3 was assessed using fluorescent immunohistochemistry. In proximal, middle, and distal small intestine, SGLT1 function in dogs was 1.9- to 2.3-fold higher than in cats (P = 0.037, P = 0.0011, P = 0.027, respectively), and SGLT1 protein abundance followed an identical pattern. Both cats and dogs express T1R3 in a subset of intestinal epithelial cells, and dogs, but not cats, express T1R2. In proximal and middle regions, there were 3.1- and 1.6-fold higher lactase (P = 0.006 and P = 0.019), 4.4- and 2.9-fold higher sucrase (both P < 0.0001), and 4.6- and 3.1-fold higher maltase activity (P = 0.0026 and P = 0.0005), respectively, in the intestine of dogs compared with cats. Dogs have a potential higher capacity to digest and absorb carbohydrates than cats. Cats may suffer from carbohydrate malabsorption following ingestion of high-carbohydrate meals. However, dogs have a digestive ability to cope with diets containing significant levels of carbohydrate.

Reliability of near-infrared spectroscopy in people with dark skin pigmentation.

OBJECTIVE: Near-infrared spectroscopy (NIRS) is a promising non-invasive technique for the continuous monitoring of tissue oxygen delivery. NIRS detects light absorbance of haemoglobin chromophores to determine tissue oxygen saturation (StO2). As skin colour is also determined by the presence of chromophores, it is plausible that NIRS signal quality may be affected by dark skin pigmentation. METHODS: Tissue saturation in the anterior compartment of the lower leg during isometric contraction was measured using NIRS in 17 volunteers with dark skin pigmentation. Measurements were continued until StO2 was zero percent or until the signal disappeared. RESULTS: The NIRS device failed to register tissue saturation values at some point in nine of seventeen volunteers. This occurred more often in individuals with darker skin. CONCLUSIONS: In patients with a dark pigmented skin, NIRS StO2 measurements should be interpreted with caution, as melanin clearly interferes with the quality of the reflected NIRS signal.

Bitter taste transduced by PLC-beta(2)-dependent rise in IP(3) and alpha-gustducin-dependent fall in cyclic nucleotides.

Current evidence points to the existence of multiple processes for bitter taste transduction. Previous work demonstrated involvement of the polyphosphoinositide system and an alpha-gustducin (Galpha(gust))-mediated stimulation of phosphodiesterase in bitter taste transduction. Additionally, a taste-enriched G protein gamma-subunit, Ggamma(13), colocalizes with Galpha(gust) and mediates the denatonium-stimulated production of inositol 1,4,5-trisphosphate (IP(3)). Using quench-flow techniques, we show here that the bitter stimuli, denatonium and strychnine, induce rapid (50-100 ms) and transient reductions in cAMP and cGMP and increases in IP(3) in murine taste tissue. This decrease of cyclic nucleotides is inhibited by Galpha(gust) antibodies, whereas the increase in IP(3) is not affected by antibodies to Galpha(gust). IP(3) production is inhibited by antibodies specific to phospholipase C-beta(2) (PLC-beta(2)), a PLC isoform known to be activated by Gbetagamma-subunits. Antibodies to PLC-beta(3) or to PLC-beta(4) were without effect. These data suggest a transduction mechanism for bitter taste involving the rapid and transient metabolism of dual second messenger systems, both mediated through a taste cell G protein, likely composed of Galpha(gust)/beta/gamma(13), with both systems being simultaneously activated in the same bitter-sensitive taste receptor cell.

[Dyspnea or confusion after trauma? Consider fat embolism syndrome]. / Benauwde of verwarde patiënt na trauma? Denk aan het vetemboliesyndroom.

Three patients, 2 women aged 26 and 19 years and a 65-year-old man, underwent surgical fracture treatment after a motor vehicle accident with fractures of the lower extremity. They developed respiratory distress from fat embolism syndrome. After maximal support in the ICU 2 of them died and 1 recovered. Fat embolism syndrome is a clinical condition mostly seen after long bone fractures. The main features are respiratory distress, cerebral confusion and a petechial rash. Usually the presentation is quite benign, but severe morbidity and even mortality can occur in some cases. It is caused by a combination of a mechanical and a biochemical pathway. Therapeutic options consist of respiratory and haemodynamic support. Preventive measures are rapid fracture fixating, good analgesia, adequate fluid infusion and tissue oxygenation.

Receptor and transduction processes for umami taste.

The unique taste of umami argues for a specific receptor at the taste cell level. The taste synergism between monosodium glutamate (MSG) and certain 5'-ribonucleotides provides a pharmacologic test for hypothetical mechanisms of umami taste. Early neurophysiologic and biochemical studies demonstrated specific recognition of L-glutamate by taste tissue and suggested that the synergism found with certain 5'-ribonucleotides was due to a peripheral event. The search for a receptor for umami relies at present on the data in the literature on central nervous system (CNS) glutamate receptors. These data distinguish several classes of receptors on the bases of pharmacologic properties and mode of action. Two hypotheses now seek to explain umami taste transduction. One states that umami is transduced by an N-methyl-D-aspartate (NMDA)-type glutamate ion channel receptor, the other that this taste is transduced via a metabotropic-type glutamate receptor. Evidence for the first hypothesis derives from earlier reconstitution studies, revealing a glutamate-stimulated ion channel conductance whose kinetics were affected by 5'-ribonucleotides. Additional evidence is provided from more recent calcium-imaging and patch-clamp studies, both showing that an ionotropic-type receptor on rodent taste cells mediates glutamate-induced depolarization. Evidence for the second mechanism derives from studies that located the message for an metabotropic-type (mGluR4) receptor to rat taste buds, and from whole-cell patch-clamp recordings that revealed sustained cellular conductances to glutamate and an mGluR4 agonist. It appears likely that both mechanisms are involved in umami taste transduction, suggesting the possibility that reception and transduction of the umami signal constitute a collective property of a number of cells within the taste bud.

Amino acid-activated channels in the catfish taste system.

Membrane vesicles derived from external taste epithelia of channel catfish (Ictalurus punctatus) were incorporated into lipid bilayers on the tips of patch pipettes. Consistent with previous experiments (Teeter, J. H., J. G. Brand, and T. Kumazawa. 1990. Biophys. J. 58:253-259), micromolar (0.5-200 microM) concentrations of L-arginine (L-Arg), a potent taste stimulus for catfish, activated a nonselective cation conductance in some bilayers, which was antagonized by D-Arg. Two classes of L-Arg-gated receptor/channels were observed in reconstituted taste epithelial membranes: one with a unitary conductance of 40-60 pS, and the other with a conductance of 75-100 pS. A separate class of nonselective cation channels, with a conductance of 50-65 pS, was activated by high concentrations of L-proline (L-Pro) (0.1-3 mM), which is the range necessary to elicit neural responses in catfish taste fibers. The L-Pro-activated channels were not affected by either L- or D-Arg, but were blocked by millimolar concentrations of D-Pro. Conversely, neither L- nor D-Pro altered the activity of either class of L-Arg-activated channels, which were blocked by micromolar concentrations of D-Arg. These results are consistent with biochemical, neurophysiological, and behavioral studies indicating that taste responses of channel catfish to L-Arg are mediated by high-affinity receptors that are part of or closely coupled to nonselective cation channels directly gated by low concentrations of L-Arg, while responses to L-Pro are mediated by distinct, low-affinity receptors also associated with nonselective cation channels.

Cluster organization of ion channels formed by the antibiotic syringomycin E in bilayer lipid membranes.

The cyclic lipodepsipeptide, syringomycin E, when incorporated into planar lipid bilayer membranes, forms two types of channels (small and large) that are different in conductance by a factor of sixfold. To discriminate between a cluster organization-type channel structure and other possible different structures for the two channel types, their ionic selectivity and pore size were determined. Pore size was assessed using water-soluble polymers. Ion selectivity was found to be essentially the same for both the small and large channels. Their reversal (zero current) potentials with the sign corresponding to anionic selectivity did not differ by more than 3 mV at a twofold electrolyte gradient across the bilayer. Reduction in the single-channel conductance induced by poly(ethylene glycol)s of different molecular weights demonstrated that the aqueous pore sizes of the small and large channels did not differ by more than 2% and were close to 1 nm. Based on their virtually identical selectivity and size, we conclude that large syringomycin E channels are clusters of small ones exhibiting synchronous opening and closing.

The arginine taste receptor. Physiology, biochemistry, and immunohistochemistry.

The amino acid, L-arginine (L-Arg), is a potent taste stimulus for the channel catfish, Ictalurus punctatus. Receptor binding studies demonstrated a high-affinity binding of L-Arg to putative taste receptor sites. This binding could be inhibited by preincubation of the tissue in the lectins Phaseolus vulgaris agglutinin (PHA) and Ricinus communis agglutinin I (RCA I). Neurophysiological studies demonstrated that the L-Arg receptor is a stimulus-gated ion channel type receptor whose conductance was stimulated by L-Arg and inhibited by D-arginine (D-Arg). To purify the receptor we subjected CHAPS solubilized partial membrane preparation from barbel epithelium to RCA I lectin affinity chromatography. The bound proteins were eluted with D-galactose. When these proteins were reconstituted into lipid bilayers, L-Arg activated single channel currents with conductances between 45 and 85 pS. Sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the eluted protein showed a distinct band at approximately 83 kDa. Polyclonal antibodies raised against this 83-kDa band in guinea pigs reacted with numerous small (approximately 1 micron) sites within the taste pore of every taste bud when applied to fixed nonpermeabilized barbels. This observation suggests that the antibodies recognize an externally-facing epitope of the putative Arg receptor. The antibodies also inhibited L-Arg-stimulated currents in reconstitution studies. Sephacryl S-300 HR chromatography of the eluant from the affinity column showed a high molecular weight peak (> 700 kDa) which was recognized by the antibodies. Reconstitution of the protein from this peak into a lipid bilayer resulted in L-Arg-stimulated channels that could be inhibited by D-Arg. This high molecular weight component may be aggregates of the arginine taste receptor.

Properties of ionic channels formed by the antibiotic syringomycin E in lipid bilayers: dependence on the electrolyte concentration in the bathing solution.

Using the planar lipid bilayer technique, organization of ionic channels formed by the lipodepsipeptide antibiotic syringomycin E applied to one (cis) side of a lipid bilayer was studied. Low concentrations of NaCl (0.01-0.1 M) induced the opening and closing of two types of channels - "small" and "large". The large channels had single channel conductances approximately six times greater than those of the small channels. An increase in the NaCl concentration (0.6-1.0 M) decreased almost completely the chance to reveal the large channels. Although the syringomycin channels exhibited the anion selectivity within the entire range of NaCl concentrations in the bathing solutions (from 0.001 to 1.0 M) whereas the concentration gradients across the bilayers were 2 and 4, the transfer numbers for Cl-decreased with an increase in the mean NaCl concentration (from 0.83 for 0.005 M to 0.70 for 0.5 M). Moreover, at each mean value of NaCl concentration, all conductance levels had the same ion selectivity (identical reversal potential). These results suggest that at low NaCl concentrations the large channels are clusters of small channels which synchronously open and close, while at high electrolyte concentrations the screening of the charged groups responsible for channel interactions prevents the cluster formation. A new theoretical approach for the estimation of the channel radius and the number of elementary charges located at its inner surface (based on the experimental curve of the dependence of transfer number on the NaCl concentration) was developed. Based on this theoretical approach, the channel radius equal to 1 nm and one elementary charge located at its inner surface were obtained.

Selectivity and response characteristics of human olfactory neurons.

Transduction mechanisms were investigated in human olfactory neurons by determining characteristics of odorant-induced changes in intracellular calcium concentration ([Ca2+]i). Olfactory neurons were freshly isolated from nasal biopsies, allowed to attach to coverslips, and loaded with the calcium-sensitive indicator fura-2. Changes in [Ca2+]i were studied in response to exposure to individual odors, or odorant mixtures composed to distinguish between transduction pathways mediated by adenosine 3'5'-monophosphate (cAMP; mix A) or inositol 1,4,5-trisphosphate (InsP3; mix B). Overall, 52% of biopsies produced one or more odorant-responsive olfactory neurons, whereas 24% of all olfactory neurons tested responded to odorant exposure with a change in [Ca2+]i. As in olfactory neurons from other species, the data suggest that odorant exposure elicited calcium influx via second-messenger pathways involving cAMP or InsP3. Unlike olfactory neurons from other species that have been tested, some human olfactory neurons responded to odorants with decreases in [Ca2+]i. Also in contrast with olfactory neurons from other species, human olfactory neurons were better able to discriminate between odorant mixtures in that no neuron responded to more than one type of odor or mixture. These results suggest the presence of a previously unreported type of olfactory transduction mechanism, and raise the possibility that coding of odor qualities in humans may be accomplished to some degree differently than in other vertebrates, with the olfactory neuron itself making a greater contribution to the discrimination process.

The effect of sterols on the sensitivity of membranes to the channel-forming antifungal antibiotic, syringomycin E.

The ability of three sterols of different structure to influence the interaction of syringomycin E (an antifungal antibiotic that forms voltage dependent channels in planar lipid bilayers) with a planar lipid bilayer was evaluated. The rate of increase of bilayer conductance induced by syringomycin E was about 1000-times less in bilayers containing 50 mol% of cholesterol compared to bilayers without sterols. The effect of ergosterol (the primary sterol of fungal cells) on the sensitivity of bilayers to syringomycin E was much weaker than that of cholesterol, while stigmasterol (one of the main sterols of plant cells) did not significantly influence the ability of syringomycin E to induce a conductance increase in the bilayer. None of the sterols altered the single channel conductance properties of syringomycin E. These observations suggest that cholesterol affects the sensitivity of target membranes to syringomycin E by enlarging the energy barrier for channel formation rather than participating in channel formation itself.

Differential localization of putative amino acid receptors in taste buds of the channel catfish, Ictalurus punctatus.

The taste system of catfish, having distinct taste receptor sites for L-alanine and L-arginine, is highly sensitive to amino acids. A previously described monoclonal antibody (G-10), which inhibits L-alanine binding to a partial membrane fraction (P2) derived from catfish (Ictalurus punctatus) taste epithelium, was found in Western blots to recognize a single band, at apparent MW of 113,000 D. This MW differs from the apparent MW for the presumed arginine receptor identified previously by PHA-E lectin affinity. In order to test whether PHA-E lectin actually reacts with the arginine-receptor, reconstituted membrane proteins partially purified by PHA-E affinity were used in artificial lipid bilayers. These reconstituted channels exhibited L-arginine-activated activity similar to that found in taste cell membranes. Accordingly, we utilized the PHA-E lectin and G-10 antibody as probes to differentially localize the L-alanine and L-arginine binding sites on the apical surface of catfish taste buds. Each probe labels numerous, small (0.5-1.0 micron) patches within the taste pore of each taste bud. This observation suggests that each bud is not tuned to a single taste substance, but contains putative receptor sites for both L-arginine and L-alanine. Further, analysis of double-labeled tissue reveals that the PHA-E and G-10 sites tend to be separate within each taste pore. These findings imply that in catfish, individual taste cells preferentially express receptors to either L-arginine or L-alanine. In addition, PHA-E binds to the apices of solitary chemoreceptor cells in the epithelium, indicating that this independent chemoreceptor system may utilize some receptor sites similar to those in taste buds.

Measurement of membrane potential and [Ca2+]i in cell ensembles: application to the study of glutamate taste in mice.

We have studied the spectral properties of the voltage-sensitive dye, 1-(3-sulfonatopropyl)-4-[beta [2-(di-n-octylamino)-6-naphtyl]vinyl] pyridinium betaine (di-8-ANEPPS), and the Ca(2+)-sensitive dye, fura-2, in azolectin liposomes and in isolated taste buds from mouse. We find that the fluorescence excitation spectra of di-8-ANEPPS and fura-2 are largely nonoverlapping, allowing alternate ratio measurements of membrane potential and intracellular calcium ([Ca2+]i). There is a small spillover of di-8-ANEPPS fluorescence at the excitation wavelengths used for fura-2 (340 and 360 nm). However, voltage-induced changes in the fluorescence of di-8-ANEPPS, excited at the fura-2 wavelengths, are small. In addition, di-8-ANEPPS fluorescence is localized to the membrane, whereas fura-2 fluorescence is distributed throughout the cytoplasm. Because of this, the effect of spillover of di-8-ANEPPS fluorescence in the [Ca2+]i estimate is < 1%, under the appropriate conditions. We have applied this method to study of the responses of multiple taste cells within isolated taste buds. We show that membrane potential and [Ca2+]i can be measured alternately in isolated taste buds from mouse. Stimulation with glutamate and glutamate analogs indicates that taste cells express both metabotropic and ionotropic receptors. The data suggest that the receptors responding to 2-amino-4-phosphonobutyrate (L-AP4), presumably metabotropic L-glutamate receptors, do not mediate excitatory glutamate taste responses.