The effect of breathing an ambient low-density, hyperoxic gas on the perceived effort of breathing and maximal performance of exercise in well-trained athletes

BACKGROUND

The role of the perception of breathing effort in the regulation of performance of maximal exercise remains unclear.

AIMS

To determine whether the perceived effort of ventilation is altered through substituting a less dense gas for normal ambient air and whether this substitution affects performance of maximal incremental exercise in trained athletes.

METHODS

Eight highly trained cyclists (mean SD) maximal oxygen consumption (VO(2)max) = 69.9 (7.9) (mlO(2)/kg/min) performed two randomised maximal tests in a hyperbaric chamber breathing ambient air composed of either 35% O(2)/65% N(2) (nitrox) or 35% O(2)/65% He (heliox). A ramp protocol was used in which power output was incremented at 0.5 W/s. The trials were separated by at least 48 h. The perceived effort of breathing was obtained via Borg Category Ratio Scales at 3-min intervals and at fatigue. Oxygen consumption (VO(2)) and minute ventilation (V(E)) were monitored continuously.

RESULTS

Breathing heliox did not change the sensation of dyspnoea: there were no differences between trials for the Borg scales at any time point. Exercise performance was not different between the nitrox and heliox trials (peak power output = 451 (58) and 453 (56) W), nor was VO(2)max (4.96 (0.61) and 4.88 (0.65) l/min) or maximal V(E) (157 (24) and 163 (22) l/min). Between-trial variability in peak power output was less than either VO(2)max or maximal V(E).

CONCLUSION

Breathing a less dense gas does not improve maximal performance of exercise or reduce the perception of breathing effort in highly trained athletes, although an attenuated submaximal tidal volume and V(E) with a concomitant reduction in VO(2) suggests an improved gas exchange and reduced O(2) cost of ventilation when breathing heliox.

Ovarian ligament adenomyoma: a case report

BACKGROUND

Adenomyoma is a benign tumour composed of smooth muscle and benign endometrium. These tumours typically originate within the uterus. An extra-uterine adenomyoma is a rare entity.

CASE

We report a case of extra-uterine adenomyoma of the ovarian ligament, which was an incidental finding during a total abdominal hysterectomy and bilateral salpingo-oophorectomy for a benign ovarian tumour in a postmenopausal woman. The mass was round with uterine-type smooth muscle and scattered functional endometrial glands and stroma.

DISCUSSION

Only seven other cases of an extra-uterine uterine-like mass are reported in the literature. There have been no cases of adenomyoma in the ovarian ligament reported until now.

CONCLUSION

It is most likely that this uterine-like mass arose from the tissues of the secondary müllerian system.

Die Transplantatniere: Farbkodierte Duplex-Sonographie und kontrastmittelverstärkte Sonographie in der Beurteilung nephrologischer und chirurgischer Komplikationen

Contrast ultrasound is a promising and straightforward method that is superior to established sonographic techniques such as conventional B-mode scanning which is used for volume measurement and hematoma demonstration. Color Doppler is important for the evaluation of rejection, the detection of perfusion defects, and complete vascularization in the diagnostic evaluation of kidney grafts. Moreover, contrast US has the potential for tumor characterization in transplanted kidneys. A single examination by contrast ultrasound can answer a variety of questions with respect to the early postoperative phase and chronic damage. New applications of contrast US will arise from the further technical development of ultrasound equipment. The rapid technical advances seen in recent years have been followed by the introduction of new software tools for the analysis of raw datasets or the improved visualization of microbubbles at very low energy. Initial studies show that efficient and early diagnosis of rejection is possible. Surgical complications like perfusion defects or hematoma can also be identified.

Dignitätsbeurteilung mammasonographischer Herde mittels dreidimensionaler Darstellung

PURPOSE

The diagnostic value of 3D ultrasound (US) was evaluated in comparison to 2D US on the basis of a set of pre-defined criteria for breast lesions. The individual criteria were correlated with the histological findings and they were ranked according to their significance for lesion characterization in both 3D US and 2D US.

MATERIALS AND METHODS

A total of 92 breast lesions were examined of which 61 were malignant and 31 were benign, as confirmed by histology of core biopsy specimens (Aplio 80, Toshiba, Otawara, Japan). The 2D and 3D data sets were stored digitally. The vascular tree was stored separately using 3D fusion. In addition, a power Doppler (PD) examination was performed. A total of 644 individual images were evaluated by two independent readers. The lesions were evaluated using established criteria (BI-RADS classification). For statistical evaluation, the individual US measurements were classified according to the following two groups: those suggesting malignant lesions and those suggestive of benign lesions. Pearsons's chi-square test was performed for both groups. The 2D and 3D techniques were compared directly using kappa (kappa) statistics. Odds ratios (OR) were determined for the purpose of weighting the individual criteria. The sensitivities and specificities of 2D and 3D US were calculated.

RESULTS

The diagnostic value of 3D US was comparable to that of 2D US, with only slight differences observed for specific measurements. Analysis of 2D US data indicated that there was a strong correlation between malignant tumor growth and two specific 2D criteria: lesion margin and effect of the lesion on adjacent breast tissue (r (2) = 0.632, p < 0.001). Analysis of 3D images indicated that the significant measurements for tumor malignancy were shape and lesion margin in sagittal, transverse (r (2) = 0741, p < 0.001), and frontal views (r (2) = 0.592, p < 0.001) as well as retraction and lesion demarcation in the frontal views (r (2) = 0.649, p < 0.001). The comparison of 2D and 3D yielded primarily moderate (kappa = 0.412) to good (kappa = 0.789) agreement between the individual criteria. Crucial criteria for lesion characterization were the effect of the lesion on adjacent breast tissue (OR 47.8 [16.0-143.3]) in 2D US and the lesion margin (OR 36.4 [15.3-86.6]) and the 3 additional criteria of the frontal plane (OR 21.9-32.9) in 3D US. The two US techniques had comparable sensitivities (2D/3D 95-97 %/92-95 %) and specificities (2D/3D 54-58 %/61-67 %). The reconstructed 3D view of the vascular tree was subjectively considered to be helpful by both readers. A higher degree of vascularization was observed with 3D US.

CONCLUSIONS

The diagnostic role of 3D ultrasound in the diagnostic evaluation of breast cancer is comparable to that of 2D US. Our findings illustrate the significance of the evaluation of frontal views in lesion characterization.

Measurement of the Gerasimov-Drell-Hearn Integrand for 2H from 200 to 800 MeV

A measurement of the helicity dependence of the total inclusive photoabsorption cross section on the deuteron was carried out at MAMI (Mainz) in the energy range 200<Egamma<800 MeV. The experiment used a 4pi detection system, a circularly polarized tagged photon beam and a frozen-spin target which provided longitudinally polarized deuterons. The contribution to the Gerasimov-Drell-Hearn sum rule for the deuteron determined from the data is 407+/-20(stat)+/-24(syst) mu b for 200<Egamma<800 MeV.

Intraocular implants for extended drug delivery: therapeutic applications

An overview of ocular implants with therapeutic application potentials is provided. Various types of implants can be used as slow release devices delivering locally the needed drug for an extended period of time. Thus, multiple periocular or intraocular injections of the drug can be circumvented and secondary complications minimized. The various compositions of polymers fulfilling specific delivery goals are described. Several of these implants are undergoing clinical trials while a few are already commercialized. Despite the paramount progress in design, safety and efficacy, the place of these implants in our clinical therapeutic arsenal remains limited. Miniaturization of the implants allowing for their direct injection without the need for a complicated surgery is a necessary development avenue. Particulate systems which can be engineered to target specifically certain cells or tissues are another promising alternative. For ocular diseases affecting the choroid and outer retina, transscleral or intrasscleral implants are gaining momentum.

DYX1C1 functions in neuronal migration in developing neocortex

Rodent homologues of two candidate dyslexia susceptibility genes, Kiaa0319 and Dcdc2, have been shown to play roles in neuronal migration in developing cerebral neocortex. This functional role is consistent with the hypothesis that dyslexia susceptibility is increased by interference with normal neural development. In this study we report that in utero RNA interference against the rat homolog of another candidate dyslexia susceptibility gene, DYX1C1, disrupts neuronal migration in developing neocortex. The disruption of migration can be rescued by concurrent overexpression of DYX1C1, indicating that the impairment is not due to off-target effects. Transfection of C- and N-terminal truncations of DYX1C1 shows that the C-terminal TPR domains determine DYX1C1 intracellular localization to cytoplasm and nucleus. RNAi rescue experiments using truncated versions of DYX1C1 further indicate that the C-terminus of DYX1C1 is necessary and sufficient to DYX1C1's function in migration. In conclusion, DYX1C1, similar to two other candidate dyslexia susceptibility genes, functions in neuronal migration in rat neocortex.

[Signal loss in magnetic resonance imaging caused by intraoral anchored dental magnetic materials]

PURPOSE

To measure the maximum extent of the signal loss areas in the center of the susceptibility artifacts generated by ferromagnetic dental magnet attachments using three different sequences in the 1.5 and 3.0 Tesla MRI.

MATERIALS AND METHODS

Five different pieces of standard dental magnet attachments with volumes of 6.5 to 31.4 mm(3) were used: a NdFeB magnet with an open magnetic field, a NdFeB magnet with a closed magnetic field, a SmCo magnet with an open magnetic field, a stainless steel keeper (AUM-20) and a PdCo piece. The attachments were placed between two cylindrical phantoms and examined in 1.5 and 3.0 Tesla MRI using gradient echo and T1- and T2-weighted spin echoes. We measured the maximum extent of the generated signal loss areas parallel and perpendicular to the direction of B (O).

RESULTS

In gradient echoes the artifacts were substantially larger and symmetrically adjusted around the object. The areas with total signal loss were mushroom-like with a maximum extent of 7.4 to 9.7 cm parallel to the direction of B (O) and 6.7 to 7.4 cm perpendicular to B (O). In spin echoes the signal loss areas were obviously smaller, but not centered. The maximum values ranged between 4.9 and 7.2 cm (parallel B (O)) and 3.6 and 7.0 cm (perpendicular B (O)). The different ferromagnetic attachments had no clinically relevant influence on the signal loss neither in 1.5 T nor 3.0 T MRI.

CONCLUSIONS

Ferromagnetic materials used in dentistry are not intraorally standardized. To ensure, that the area of interest is not affected by the described artifacts, the maximum extent of the signal loss area should be assumed: a radius of up to 7 cm in 1.5 and 3.0 T MRI by T1 and T2 sequences, and a radius of up to 10 cm in T2* sequences. To decide whether magnet attachments have to be removed before MR imaging, physicians should consider both the intact retention of the keepers and the safety distance between the ferromagnetic objects and the area of interest.

In vitro and in vivo pharmacology of synthetic olivetol- or resorcinol-derived cannabinoid receptor ligands

BACKGROUND AND PURPOSE

We have previously reported the development of CB-25 and CB-52, two ligands of CB1 and CB2 cannabinoid receptors. We assessed here their functional activity.

EXPERIMENTAL APPROACH

The effect of the two compounds on forskolin-induced cAMP formation in intact cells or GTP-gamma-S binding to cell membranes, and their action on nociception in vivo was determined.

KEY RESULTS

CB-25 enhanced forskolin-induced cAMP formation in N18TG2 cells (EC50 approximately 20 nM, max. stimulation = 48%), behaving as an inverse CB1 agonist, but it stimulated GTP-gamma-S binding to mouse brain membranes, behaving as a partial CB1 agonist (EC50 =100 nM, max. stimulation = 48%). At human CB1 receptors, CB-25 inhibited cAMP formation in hCB1-CHO cells (EC50 = 1600 nM, max. inhibition = 68% of CP-55,940 effect). CB-52 inhibited forskolin-induced cAMP formation by N18TG2 cells (IC50 = 450 nM, max. inhibition = 40%) and hCB1-CHO cells (EC50 = 2600 nM, max. inhibition = 62% of CP-55,940 effect), and stimulated GTP-gamma-S binding to mouse brain membranes (EC50 = 11 nM, max. stimulation approximately 16%). Both CB-25 and CB-52 showed no activity in all assays of CB2-coupled functional activity and antagonized CP55940-induced stimulation of GTP-gamma-S binding to hCB2-CHO cell membranes. In vivo, both compounds, administered i.p., produced dose-dependent nociception in the plantar test carried out in healthy rats, and antagonised the anti-nociceptive effect of i.p. WIN55,212-2. In the formalin test in mice, however, the compounds counteracted both phases of formalin-induced nociception.

CONCLUSIONS AND IMPLICATIONS

CB-25 and CB-52 behave in vitro mostly as CB1 partial agonists and CB2 neutral antagonists, whereas their activity in vivo might depend on the tonic activity of cannabinoid receptors.