Two Synchronous Neonatal Tumors: An Extremely Rare Case.

We report a case of a newborn with two synchronous tumors-sialoblastoma and hepatoblastoma-diagnosed at 20 weeks of gestation by magnetic resonance imaging (MRI) and ultrasonography (US). The aim of this study was to describe the management of this case together with a review of the literature. Our patient had a large facial tumor associated with extremely high alpha-fetoprotein levels. Diagnosis of the tumors was made by surgical biopsy, showing typical features in both. Sialoblastoma is a potentially aggressive tumor. In our case, the Ki67 index in the sialoblastoma was between 20 and 30%, indicating a possibly unfavorable behavior. The infant underwent surgery and chemotherapy in different steps. Complete surgical resection with clean margins is considered to be the best treatment option for sialoblastoma. Only four similar cases were previously reported. Timely management by a multidisciplinary team is essential in these difficult cases. In our patient, outcome was good at the time of this report.

Efficient graphene saturable absorbers on D-shaped optical fiber for ultrashort pulse generation.

We demonstrated a method to construct high efficiency saturable absorbers based on the evanescent light field interaction of CVD monolayer graphene deposited on side-polished D-shaped optical fiber. A set of samples was fabricated with two different core-graphene distances (0 and 1 µm), covered with graphene ranging between 10 and 25 mm length. The mode-locking was achieved and the best pulse duration was 256 fs, the shortest pulse reported in the literature with CVD monolayer graphene in EDFL. As result, we find a criterion between the polarization relative extinction ratio in the samples and the pulse duration, which relates the better mode-locking performance with the higher polarization extinction ratio of the samples. This criterion also provides a better understanding of the graphene distributed saturable absorbers and their reproducible performance as optoelectronic devices for optical applications.

[Influence of gender on the potency and course of action of rocuronium bromide]. / Papel del género en la potencia y curso de acción del bromuro de rocuronio.

OBJECTIVE: The correlation between gender and the potency of certain neuromuscular blockers, including rocuronium, has been investigated. However, the methods used have been inconsistent. This study aimed to look further at the role of gender in order to arrive at definitive conclusions. PATIENTS AND METHODS: In a first and second phases of the study, rocuronium dose-response curves were constructed for patient groups as follows: 2 mixed-gender groups, 2 female groups, and 2 male groups. One group in each set received a single dose. In the other group the effect of the accumulated dose was measured after each of 3 fractions. The doses were transformed logarithmically. The effect was monitored by electromyography, and probit analysis was used to calculate the effective dose to induce 50%, 90% and 95% of the maximum effect (ED50, ED90 and ED95, respectively) in each patient. In the third phase, a bolus dose of 400 microg-Kg(-1) was administered to 3 additional groups. Onset time, maximum effect, speed of onset, duration of effect as the 10%-25% recovery index, and speed of recovery were recorded. In the fourth phase analysis was restricted to measurements during the period of onset. RESULTS: No significant between-group differences in mean (SD) ED50, ED90, or ED95 values were observed after single doses (female group: 176 [68], 252 [97], and 285 [110] microg x Kg(-1), respectively; male group: 187 [69], 271 [100], and 307 [114] microg x Kg(-1); mixed group: 172 [73], 233 [98], and 258 [109] microg x Kg(-1)). Assessment of effect after cumulative fracional doses gave the following mean values for ED50, ED90, and ED95: 249 (63), 310 (79), and 334 (85) microg x Kg(-1) for the female group; 261 (60), 327 (75), and 354 (81) microg x Kg(-1) for the male group; and 242 (70), 305 (88), and 330 (95) microg x Kg(-1) for the mixed group. No significant differences in measures of effect were found after bolus administration in the third phase. CONCLUSIONS: These results suggest that there is no significant effect of gender on potency or course of action of rocuronium bromide. Reports of such differences based on previous studies may be the result of problems in the methods applied.

[Correlation between the molar potency of atracurium and its onset time and speed of action]. / Correlación entre la concentración molar del atracurio y su tiempo de comienzo o velocidad de acción.

OBJECTIVE: To study the correlation between the subparalyzing dose of atracurium and its onset time and speed of action. MATERIAL AND METHODS: Six groups of patients received 0.36, 0.68, 0.98, 1.44, 1.77, or 2.06 times the median effective dose of atracurium. The maximal effect, onset time, molar potency (microM kg(-1)) and speed of action (relationship between time in seconds and percentage of maximum effect and between percentage of maximum effect and time) of each dose were measured. The values were converted to logarithms and square roots to test for correlations. The regression line provided the equation, coefficient of determination (R2), and statistical significance. RESULTS: The correlation between the logarithms of molar potency and onset time was poor and not statistically significant (R2 = 0.564, P = .138), whereas the correlations between the logarithms of molar potency and speed of action (seg/%) (s/maximum % effect, R2 = 0.952; and maximum % effect/s, R2 = 0.984) were strong and statistically significant (P < .0001) The regression formulas were able to predict the onset time. The results were similar when the values were converted to their square roots. CONCLUSION: The onset time of a neuromuscular blocker is linked to its effect and its permeability is linked to the size of its molecules or the molar potency, which is dose-dependent. In the case of atracurium, this correlation was poor and not significant. This finding coincides with those of other authors, who found that atracurium was distant from the regression line for equipotent quantities of different neuromuscular blockers. Substituting onset time with speed of action, however, made it possible to establish a strong and significant correlation. Our results suggest that the speed of action of atracurium depends on the size of its molecule.

[Interaction between mivacurium and succinylcholine from a different point of view]. / Interacción entre mivacurio y succinilcolina: vista desde otra perspectiva.

OBJECTIVES: Succinylcholine (SCH) may first be used and continue with mivacurium (MIV). MIV has been suggested as a pretreatment. Conflicting results arises from studies on SCH-MIV interaction. The following trial revisits this interaction. PATIENTS AND METHODS: The patients were intubated after randomized administration of 100 microg x Kg(-1) of mivacurium (group 1) or 1 mg x Kg(-1) of succinylcholine and, after 50% recovery, 100 microg x Kg(-1) of mivacurium (group 2). A third group received the same regimen as group 2, preceded by pretreatment with 10 microg x Kg(-1) of mivacurium. Maximum effect (MAX), onset time, the 10%-25% recovery index, and duration of effect of mivacurium were determined by electromyography. In groups 2 and 3, the corrected MAX was defined as the difference between the actual MAX effect and the residual block after administration of succinylcholine, and speed of action was defined as the ratio between MAX or corrected MAX and onset time. Data were subjected to analysis of variance and Student-Newman-Keuls and t tests for bivariate comparisons. A value of P less than 0.05 was considered significant. RESULTS: Groups 2 and 3 had significantly greater MAX effects (97% and 98%, respectively) in comparison with group 1 (93%), shorter onset times (135 and 158 seconds in groups 2 and 3 vs 279 seconds in group 1), and greater speed of action without changes in duration of effect. MAX was halved when corrected (to 47% and 49% in groups 2 and 3, respectively), and speed of action was significantly reduced (from 1.34 and 1.62 seconds/% in groups 2 and 3 respectively, to 2.69 and 3.36 seconds/%). Mivacurium pretreatment did not produce relevant clinical changes. CONCLUSIONS: When mivacurium is used before the effects of succinylcholine disappear, a residual effect is not usually taken into consideration. This study corrected MAX and calculated speed of action, demonstrating a reduction in net block and speed of action, consistent with an antagonistic action when the 2 blockers are administered sequentially.

[Rocuronium: onset time or speed of action?]. / Rocuronio: tiempo de comienzo o velocidad de acción?

OBJECTIVE: Rocuronium has been said to have an initially rapid onset of action followed by a slower final approach to maximum effect, the supporting data showing only that time to 75% of blockade is more rapid. Expressions of velocity are derived from basic measures such as length and time. The aim of our study was to confirm the onset characteristics of rocuronium by using appropriate expressions of velocity. PATIENTS AND METHODS: After consenting, 25 adults scheduled for elective surgery were anesthetized, using a bolus dose of rocuronium of 400 microg Kg(-1) for relaxation. Electromyography was used to determine maximal effect, time to reach 80% of a full neuromuscular block, onset time, the time interval between these two points, and the differential blockade produced during each period. Velocity for each period was calculated as the ratio between the percentage of block produced per amount of time elapsed (%/s) during each respective period. The ratio between time and blockade (s/%) was also calculated. RESULTS: More blockade was produced per second (velocity) during the initial period of activity (0.55%/s) than during the final period (0.109%/s). The average velocity during the onset period overall (0.33%/s) lay between those two figures. Rocuronium requires less time (acting fast) to achieve an initial effect (1.95 s/%) than it does to reach the final effect (10.8 s/%). The ratio of early to late speed of onset was 5.8 +/- 3.5. CONCLUSION: Using appropriate expressions and calculations, we can unequivocally conclude that rocuronium has a biphasic onset that is initially rapid and then slower. The rate of action is nearly 6 times faster at the beginning.

Interacción entre el rocuronio y vecuronio / Interaction between rocuronium and vecuronium

La interacción entre rocuronio y vecuronio fue estudiada por electromiografía en 135 pacientes adultos electivos, anestesiados con sevoflurano. En la primera parte los relajantes musculares fueron administrados de acuerdo a la técnica del cebado recíproco, demostrándose que al inyectar vecuronio como cebado antes del rocuronio se provoca un significativo aumento en el efecto de este último y de la misma manera una reducción en el tiempo de su comienzo ("onset time"), sin cambios de la duración clínica. No se reportan hallazgos estadísticos cuando el rocuronio fue empleado como cebado previo del vecuronio. En la segunda parte, con el uso secuencial de dosis clínicas no paralizantes de ambas drogas, se puso en evidencia que la administración previa de vecuromo, acorta el comienzo de acción de una segunda administración de rocuronio, sin que otras diferencias significativas puedan obtenerse con la secuencia inversa. El presente estudio puede ser considerado como una interesante data que deberá tomarse en cuenta para ulteriores análisis de la interacción entre bloqueadores neuromusculares y en este caso particular cuando ambas drogas son aminoesteroideos. Debido a los pocos hallazgos consistentes, estos resultados parecen servir de apoyo a otras investigaciones que consideran esta interacción como un aditivismo. Pocas ventajas aparentes ofrece esta técnica para ser útil desde el punto de vista clínico

[Effects of non-depolarizing muscle relaxants on the duration of mivacurium]. / Efecto de algunos relajantes musculares no despolarizantes sobre la duración del mivacurio.

The interaction between Mivacurium and several muscle relaxants results in a slow recovery. We have previously described that small doses of d-tubocurarine prolong the duration of two successful administrations of Mivacurium. The present investigation was designed to uncover if such an effect could be observed after other neuro-muscular blocking drugs were administered, and if so, its consistency during the different methods of their use. Patients (n = 224) were anesthetized with Enflurane and randomly assigned to two control groups which received 100 micrograms/Kg-1 Mivacurium as a bolus or primed. Other groups received: Rocuronium (60 micrograms/Kg-1), Vecuronium (10 micrograms/Kg-1), Atracurium (60 micrograms/Kg-1), d-tubocurarine (50 micrograms/Kg-1) or Pancuronium (8 micrograms/Kg-1) before, after or as a mixture with 90 micrograms/Kg-1 of Mivacurium. The clinical effect was monitored by electromyography and the results show that all these agents prolong the duration of Mivacurium, the last three in a statistically significant fashion independently of the mode of administration. Current hypothesis are reviewed, but no definitive clues are obtained to explain the present results. Our conclusions must be considered as further research on the interaction between non-depolarizing muscle relaxants and a base for new theories on interactions.