Paraspinal desmoid fibromatosis after lumbar epidural analgesia

A 14-year-old girl with cerebral palsy presented for bilateral lower limb surgery for spasticity. A lumbar epidural catheter was sited under general anaesthesia on the third attempt and used intra-operatively with good effect. A local anaesthetic infusion was used for postoperative analgesia but was noted to be leaking under the dressing with a patchy, unilateral block. The catheter was therefore removed on the second postoperative day. Following discharge, the patient progressively developed new back and leg pain for which she was re-admitted seven weeks later. This was investigated and initially thought to be myositis of the erector spinae muscles on magnetic resonance imaging. When the patient failed to respond to treatment, a muscle biopsy demonstrated desmoid fibromatosis. Trauma may cause or accelerate the development of desmoid fibromatosis, which has also been theorised to arise from scar tissue in previously injured areas. We hypothesise that challenging epidural placement or the leakage of the local anaesthetic agent into the surrounding muscular tissue, inducing local myonecrosis, could have been the triggering or accelerating event in tumour development. This may be the first reported case of extra-abdominal desmoid fibromatosis in association with epidural placement.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Archaeological evidence for dental innovation: an eighteenth century porcelain dental prosthesis belonging to Archbishop Arthur Richard Dillon

During archaeological investigation by Gifford of St Pancras Old Church burial ground, on the eastern edge of Somers Town, London, in advance of construction of the new London terminus for the Channel Tunnel Rail Link, a full porcelain denture was discovered. The high quality porcelain dentures, manufactured in the late eighteenth century French style, may have been brought with their owner, Archbishop Arthur Richard Dillon, on his journey into exile. There is evidence of prolonged use, not only for cosmetic or vocal functions but also in mastication. The dentures are unique archaeological artefacts and represent a pivotal time in dental history, with the adoption of new materials and methods of manufacture. They reflect a period of significant social and economic change for the upper echelons of French society. This paper outlines the development of porcelain dentures, discusses the prosthesis, their owner, and a possible provenance.

Chemically accurate protein structures: validation of protein NMR structures by comparison of measured and predicted pKa values

A new method is presented for evaluating the quality of protein structures obtained by NMR. This method exploits the dependence between measurable chemical properties of a protein, namely pKa values of acidic residues, and protein structure. The accurate and fast empirical computational method employed by the PROPKA program ( http://www.propka.chem.uiowa.edu) allows the user to test the ability of a given structure to reproduce known pKa values, which in turn can be used as a criterion for the selection of more accurate structures. We demonstrate the feasibility of this novel idea for a series of proteins for which both NMR and X-ray structures, as well as pKa values of all ionizable residues, have been determined. For the 17 NMR ensembles used in this study, this criterion is shown effective in the elimination of a large number of NMR structure ensemble members.

High harmonic generation in a semi-infinite gas cell

Ten-millijoule 35-femtosecond laser pulses interact with a cell of helium or neon that extends from a focusing lens to an exit foil near the laser focus. High harmonic orders in the range of 50 to 100 are investigated as a function of focal position relative to the exit foil. An aperture placed in front of the focusing lens increases the brightness of observed harmonics by more than an order of magnitude. Counter-propagating light is used to directly probe where the high harmonics are generated within the laser focus. In neon, the harmonics are generated in the last few millimeters before the exit foil, limited by absorption. In helium, the harmonics are produced over a much longer distance.

Efficacy of a novel hemostatic agent in animal models of impaired hemostasis

This study evaluated the efficacy of a novel sprayable hemostat under both normal conditions and those of compromised coagulation. CoStasistrade mark Surgical Hemostat ("CoStasis"), containing collagen, thrombin, and autologous plasma, was compared to Instattrade mark collagen sponge, an investigational fibrin sealant, and a no treatment control, for the ability to control bleeding in a rabbit kidney model. Hemostatic performance was determined by time to hemostasis and blood loss in a nonsurvival, randomized, in vivo bleeding rabbit kidney model. Under conditions of normal coagulation, as well as aspirin and heparin treatment, hemostasis was achieved faster with CoStasistrade mark than with Instattrade mark and fibrin sealant. With the exception of the time to hemostasis using Instattrade mark sponge in heparinized rabbits, all differences were statistically significant (p < 0.03, Wilcoxon). Blood loss, where measured, was lower with CoStasistrade mark than with the other hemostats under the three coagulation conditions. Statistical significance, (p < 0.03, Wilcoxon), was achieved with all comparisons except with fibrin sealant in aspirin treated animals. The combination of collagen, thrombin, and autologous plasma used in CoStasis, can achieve significantly faster hemostasis than the conventional atraumatic hemostats, collagen sponge, and fibrin sealant under normal conditions and conditions of impaired hemostasis.

A sprayable hemostat containing fibrillar collagen, bovine thrombin, and autologous plasma

BACKGROUND

A new sprayable hemostat, CoStasis hemostatic device (Cohesion Technologies Inc, Palo Alto, CA), consisting of collagen, thrombin, and autologous plasma was tested versus fibrin sealant and collagen hemostatic sponges. Performance was also monitored as fibrinogen and platelets were depleted from the plasma. In addition, the strength of the CoStasis gel, its sealing ability, its fibrillar structure, and its platelet-aggregating ability were investigated.

METHODS

Hemostatic performance was determined with an in vivo bleeding rabbit kidney and spleen model. Differential scanning calorimetry and electron microscopy were used to analyze collagen structure. Sealing ability was determined with a burst-test apparatus.

RESULTS

In the in vivo model, CoStasis was superior to fibrin sealant and collagen sponges in achieving a rapid time to hemostasis. The formulation continued to perform well when either platelets or fibrinogen was depleted. CoStasis formed weaker gels than fibrin sealant and could withstand only modest pressures. The collagen in the formulation had a fibrillar structure that was shown to aggregate human platelets.

CONCLUSIONS

CoStasis, with the two platelet activators collagen and thrombin in addition to the thrombin-catalyzed formation of fibrin and the sealing properties of the soft gel, provides an excellent atraumatic hemostat.

Hair cell regeneration and recovery of function in the avian auditory system

Chickens were exposed to an intense pure tone that destroyed the hair cells and tectorial membrane in a crescent shaped patch along the abneural edge of the basilar papilla. During the following weeks, when the hair cells and tectorial membrane were regenerating, psychophysical and electrophysiological measures were obtained to assess the time course and degree of recovery. Immediately after the exposure, the behavioral thresholds were elevated 30-40 dB and auditory temporal integration was greatly reduced; however, both measures fully recovered by 28 days post-exposure. In addition, tone-on-tone masking patterns recovered to normal. Immediately after the exposure, the thresholds of single cochlear ganglion neurons were elevated more than 30 dB, tuning curves were broader than normal, two-tone rate suppression (TTRS) boundary slopes were shallower than normal and spontaneous activity was reduced. Threshold and spontaneous discharge rate fully recovered after the exposure. Tuning and TTRS also recovered significantly in most neurons; however, some units with characteristic frequencies (CFs) near the exposure frequency showed abnormal tuning and TTRS suppression. The regeneration of the hair cells and lower honeycomb layer of the tectorial membrane is associated with considerable recovery of function; however, the incomplete recovery of tuning and TTRS in some neurons may be linked to the incomplete regeneration of the tectorial membrane.

Quantitative relationship of carboplatin dose to magnitude of inner and outer hair cell loss and the reduction in distortion product otoacoustic emission amplitude in chinchillas

The outer hair cells (OHCs) are thought to be the dominant source of distortion product otoacoustic emissions (DPOAEs) in the mammalian cochlea; however, little is known about the quantitative relationship between reduction in DPOAE amplitude and the degree of inner hair cell (IHC) and OHC loss. To examine this relationship, we measured the DPOAE input/output functions in the chinchilla before and after destroying the IHCs and/or OHCs with carboplatin. Low-to-moderate doses (38-150 mg/kg, i.p.) of carboplatin selectively destroyed some or all of the IHCs along the entire length of the cochlea while sparing the OHCs. Selective loss of all the IHCs had little effect on DPOAE amplitude as long as the OHCs were present. With high doses of carboplatin (200 mg/kg, i.p.), there was complete destruction of IHCs plus massive OHC loss that decreased from the base towards the apex of the cochlea. OHC loss resulted in a large decrease in DPOAE amplitude. DPOAE amplitude at 9.6 kHz decreased at the rate of 4.1 dB for every 10% loss of OHCs. At 7.2 and 4.8 kHz, DPOAE amplitude decreased 3.1 dB and 2.4 dB per 10% OHC loss, respectively. These results indicate that OHCs are the dominant source of DPOAEs.

Two-tone rate suppression boundaries of cochlear ganglion neurons in chickens following acoustic trauma

The purpose of the present study was to examine the effects of acoustic trauma and hair cell loss and regeneration on the two-tone rate suppression (TTRS) boundaries of cochlear ganglion neurons in chickens. Chickens were exposed for 48 hours to a 525-Hz, 120-dB SPL tone which destroyed the hair cells and tectorial membrane in a crescent-shaped patch along the abneural side of the basilar papilla. Afterwards, TTRS boundaries were recorded from cochlear ganglion neurons at 0-1, 5, 14, and 28 days postexposure. Acoustic trauma reduced the percentage of neurons with TTRS boundaries below CF (TTRSb) (52.6% to 8.2%) and above CF (TTRSa) (88.4% to 46.6%). In addition, the exposure reduced TTRS boundary slopes, elevated best suppression threshold (BST), and increased the frequency separation between the tips of the TTRS boundaries and CF. All the TTRS measures started to recover by 5 days postexposure and by 14 days and 28 days postexposure, most measures had recovered to normal levels. However, the BST, TTRS slopes, and the frequency separation of TTRSb boundaries from CF were still slightly abnormal near the exposure frequency. In addition, the percentage of neurons with TTRS below CF was reduced significantly. The partial recovery of TTRS boundaries is presumably due to the regeneration of hair cells and the lower honeycomb layer of the tectorial membrane. The residual TTRS deficits observed 28 days postexposure were most closely associated with the missing upper fibrous layer of the tectorial membrane.

Two-tone rate suppression boundaries of cochlear ganglion neurons in normal chickens

The purpose of the present study was to provide a quantitative description of two-tone rate suppression boundaries in normal chickens. The boundaries were measured in 249 cochlear ganglion neurons using a tone 20 dB above threshold at the characteristic frequency (CF). The boundaries were present in 90.4% of neurons either on both sides or only one side of CF but more frequently above CF than below CF. The best suppression thresholds were positively correlated with and, on the average, 19-25 dB higher than CF thresholds. The boundary was farther from CF and shallower below CF than above CF. The boundary slope varied slightly with CF threshold and the tuning curve slope. These results are generally consistent with previous reports from mammals except that: (1) the boundary below CF did not follow and lie above the tuning curve flank; (2) the average best suppression threshold was slightly lower below CF than above CF; (3) the boundaries below and above CF were not particularly asymmetrical.

Plasticity of response properties of inferior colliculus neurons following acute cochlear damage

1. The discharge patterns of 40 neurons in the central nucleus of the inferior colliculus (ICC) of the chinchilla were evaluated before and after acute cochlea trauma from intense tone exposure. Single-unit recordings were obtained from neurons in the ICC contralateral to the sound-stimulated ear. Cochlear trauma was induced with a short-duration (15-25 min), high-intensity pure tone (95-115 dB SPL) at a frequency above the neuron's characteristic frequency (CF). The aim of the traumatizing exposure was to damage the peripheral sensory receptors associated with frequencies above the neuron's CF. The damage was expected to attenuate inputs to the neural circuits responsible for activating the inhibitory sidebands above CF. 2. Three types of frequency-threshold tuning curves were observed before the exposure: 1) open V tuning curves (55%) that became wider as sound intensity increased; 2) level-tolerant tuning curves (37.5%) that maintained a very narrow bandwidth even at high sound intensities; and 3) upper-threshold tuning curves (7.5%) in which excitatory responses were elicited at low and moderate intensities, but not at high intensities. The traumatizing exposure caused a dramatic widening of level-tolerant (80% of sample) and upper-threshold tuning curves (100% of sample) at high sound intensities but caused almost no change in the low-threshold tip of the tuning curves. By contrast, tuning curves with an open V configuration were generally unaffected (approximately 90% of sample) by the traumatizing exposure. 3. Discharge rate-level functions in the ICC were of two general types: 1) strongly nonmonotonic (60%) or 2) saturating, monotonic (40%). The traumatizing exposure caused a significant increase in the suprathreshold discharge rates in 70% of all neurons studied. Among the neurons with strongly nonmonotonic discharge rate-level functions, 93% showed a significant increase in discharge rate. 4. The poststimulus time histograms (PSTH) to tone bursts were of three main types: 1) onset, 2) pauser, and 3) sustained responders. The traumatizing exposure had almost no effect on the PSTH of onset or sustained responders. However, pause PSTH frequently (75%) showed a significant decrease in the pause duration and an increase in the sustained discharge rate following the pause after the exposure. 5. The results suggest that the response properties of neurons with extremely narrow tuning curves and nonmonotonic discharge rate-level functions are shaped by an inhibitory circuit that is activated by frequencies above the high-frequency flank of the tuning curve. This inhibitory circuit modifies the excitatory response in the following ways: 1) it narrows the excitatory response area at suprathreshold intensities particularly at frequencies below CF, 2) it alters the shape of the discharge rate-level function by suppressing the discharge rates at suprathreshold intensities, and 3) it modifies the temporal discharge pattern of the pause PSTH by suppressing neural activity that occurs after the onset response. The effects of these inhibitory inputs can be reduced (disinhibition) by damaging the sensory cells in the inner ear that activate this circuit. The exact locus of the inhibitory circuit(s) is unknown but may involve inhibitory inputs located at the level of the cochlear nucleus and/or at levels up to the inferior colliculus.

Resonant frequency at the wrist in hypermobile women

The resonant frequency of the wrist has been measured in sixteen hypermobile and nine normal women at ten levels of peak torque. At the lowest level the results were identical but at the others the hypermobile values were lower. Damping and thixotropy appeared to be normal. In another group the grip strength of hypermobile subjects was similar to that of controls. The possibility that the connective tissue of the musculature of hypermobile subjects is of enhanced compliance is discussed.

Enhanced evoked response amplitudes in the inferior colliculus of the chinchilla following acoustic trauma

Evoked response amplitude-level functions were measured from electrodes in the inferior colliculus of the chinchilla before and after exposure to a 2 kHz pure tone of 105 dB SPL. The exposure produced approximately 20-30 dB of permanent threshold shift from 2 to 8 kHz, but little or no hearing loss at higher or lower frequencies. Generally less than 60% of the outer hair cells were missing in the region of hearing loss. The amplitude-level functions measured at 4 and 8 kHz generally showed a loss in sensitivity at low sound levels, a reduction in the maximum amplitude and sometimes steeper than normal slopes. The amplitude-level functions measured at 2 kHz also showed a loss in sensitivity; however, the maximum amplitude was often greater than normal. Even though there was no loss in sensitivity at 0.5 kHz, the amplitude-level function was steeper than normal and the maximum amplitude of the evoked response was almost always substantially larger than normal. The enhancement of the evoked response amplitude from the inferior colliculus does not appear to originate in the cochlea, but may reflect a reorganization of neural activity in the central auditory pathway.

Tremor and the anti-obesity drug BRL 26830A

The thermogenic beta 3-adrenoceptor agonist BRL 26830A has been shown to increase weight loss in dieting subjects but tremor was a frequent adverse effect. We have investigated the magnitude and nature of this tremor after a single oral dose in 18 subjects. Two complementary techniques were used to attach the recording apparatus to the subjects to give both isotonic and isometric measures of tremor. Increases of 84% and 40% respectively were found due to exaggeration of physiological tremor presumably mediated through concomitant beta 2-adrenoceptor stimulation. The use of beta 3-adrenoceptor agonist drugs in the treatment of obesity may increase but the development of an agent without tremor inducing properties would be an obvious advantage.

Evoked response narrow-band noise masking patterns in the chinchilla

Narrow-band noise masking patterns were measured at 0.5, 1, 2 and 4 kHz in the chinchilla using the auditory evoked response from the inferior colliculus. At low masker levels, the masking profiles were symmetrical and centered on the masker. However, as masker level increased, the masking profiles spread predominantly toward the high frequencies. The masking profiles obtained at 0.5 and 1 kHz, exhibited a broad plateau extending 1-2 octaves above the masker at the highest masker level (70 dB SPL) whereas those obtained at 2 and 4 kHz showed a peak. In contrast to tone-on-tone masking profiles, none of the narrow-band noise masking profiles contained a low-threshold notch on the high frequency side of the masker. The evoked response masking profiles obtained in the chinchilla were slightly wider, but qualitatively similar to those measured psychophysically in humans. Thus, the evoked response narrow-band noise masking profiles may provide a convenient way of evaluating the spread of masking in difficult-to-test subjects.

Biodynamics of the wrist in rheumatoid arthritis--the enigma of stiffness

The wrist has been moved rhythmically in the horizontal plane by sinusoidal torques provided by a printed motor. Measurements have been made on normal subjects and subjects with rheumatoid arthritis. Both groups exhibited a resonance, the oscillations being greatest when the applied torque was of certain frequency. In both groups the resonant frequency fell to approximately the same constant value when the torque was raised. While the main relationships were similar a somewhat lower torque resulted in the lowering of resonant frequency in the patients. The relationship between applied torque and peak velocity at resonance was also studied. For a given torque the motion was greater in the patients. No objective signs of increased viscous or elastic stiffness were demonstrable at the wrist in patients with rheumatoid arthritis.

Clinical identification and comparative prognosis of high-risk patients with Haemophilus influenzae meningitis

One hundred ninety-five consecutive children with Haemophilus influenzae meningitis were retrospectively reviewed to identify those patients at high risk of death or severe sequelae using a previously described clinical scoring system. One hundred sixty-nine children (86.7%) had prognostic scores less than or equal to 4.0 and all survived. Twenty-six patients (13.3%) had prognostic scores greater than or equal to 4.5 points. Five of these high-risk patients (2.6% overall) died as a direct result of their acute meningitis. Of the remaining 21 survivors, 15 were available for prospective, observer-blinded, follow-up evaluation, as compared with 15 low-risk control patients matched for age, sex, and year of admission. High-risk patients were significantly more likely to have more serious sequelae (2.0 +/- 2.1) as compared with low-risk controls (0.5 +/- 0.7). Those high-risk patients who by the choice of their treating physicians had received corticosteroids (and usually osmotic therapy as well) appeared to have outcomes similar to their matched low-risk controls and significantly better than those high-risk patients who did not receive such additional therapy.

Maximal aerobic power measurement in runners and swimmers

Five cross-country runners and five competitive swimmers performed a pulling exercise with elastic shock cords and a treadmill run to exhaustion. The mean VO2 max related to lean body mass of the runners was significantly higher than the swimmers on the treadmill (p less than 0.05) while, on the pulling test, the mean VO2 max of the swimmers was significantly higher than the runners (p less 0.01). The maximum heart rates achieved pulling were 95% of the running maximum by runners and 96% by swimmers with no significant difference between them. Their mean oxygen pulse was almost the same for maximal running but the swimmers had a significantly higher oxygen pulse than the runners for maximal pulling (p less than 0.01). The swimmers could reach about 79% of their running VO2 max by pulling while the runners used 53% of their running VO2 max.