Elucidating the temporal dynamics of optical birefringence changes in crustacean nerves

Intrinsic optical properties, such as optical birefringence, may serve as a tool for minimally invasive neuroimaging methods with high spatiotemporal resolution to aid in the study of neuronal activation patterns. To facilitate imaging neuronal activity by sensing dynamic birefringence, temporal characteristics behind the signal must be better understood. We have developed a novel nerve chamber to investigate changes in birefringence at the stimulation site, and at distances ~4-28 mm from that site. Using crustacean nerves with either heterogeneous or homogeneous size distributions of axon diameters, we found that the gradual (slow) recovery of the crossed-polarized signal is not explained by the arrival times of action potentials in smaller axons. Through studying the effects of stimulating current and voltage pulses, we hypothesize that the recovery may be caused by a capacitive-like coupling between firing axons and adjacent tissue structures, and we report data consistent with this hypothesis. This study will aid in the utilization of action-potential-related changes in birefringence to study fast changes in neuronal network activity.OCIS codes: (260.1440) Birefringence, (170.3880) Medical and biological imaging, (170.2655) Functional monitoring and imaging     

Is measurement of progesterone level prior to FSH stimulation useful in GnRH-antagonist cycles?

Aim. To reduce patient inconvenience during in vitro fertilization (IVF) cycles, some protocols delay intensive monitoring until mid-follicular stimulation. Others assess hormone levels prior to follicle-stimulating hormone (FSH) administration, not commencing stimulation until baseline progesterone (P4) levels (< 5 nmol/l) are achieved. Higher P4 levels (> 4.8 nmol/L) on the day of FSH trigger have been implicated in poorer pregnancy rates. This study evaluates the association of P4 levels at day 1–2 in gonadotrophin-releasing hormone (GnRH)-antagonist cycles with pre-trigger P4 levels and clinical pregnancy rates (CPRs). Method. All fresh GnRH-antagonist IVF cycles between June 2011 and June 2012, in which pre-FSH P4 levels were not routinely performed (group 1), were retrieved from the IVF Australia database and compared with controls (group 2). Results. There were 163 cycles in each group. P4 levels on the day of trigger were significantly higher in group 1 (3.75 vs. 2.77, p < 0.05). The incidence of pre-trigger P4 levels >4.8 nmol/l was significantly higher in group 1 (30 vs. 16, p < 0.05). The number of oocytes retrieved was higher in group 1 (11.1 vs. 9, p < 0.05), however fertilization rates were significantly lower in that group (53.6% vs. 61.2%, p < 0.05); CPRs were similar between the two groups (27.8% vs. 31.8%, p = ns). Overall, pregnancy rates were lower in cycles with pre-trigger P4 level of > 4.8 nmol/L compared with those with lower levels (15% vs. 32.5%, p < 0.05). Conclusion. We found that measurement of P4 level at early follicular phase was associated with significantly lower pre-trigger levels. However, this did not translate into a difference in CPR between the monitored and unmonitored groups. We have confirmed that elevation in pre-trigger P4 level is associated with halving of the CPR, indicating that the most important P4 measurements are those in the late follicular/pre-trigger phase.     

PCR-based clonality analysis of B-cell lymphomas in paraffin-embedded tissues: diagnostic value of immunoglobulin kappa and lambda light chain gene rearrangement investigation

Polymerase chain reaction (PCR)-based analysis, employed for detecting immunoglobulin heavy chain (IgH) gene rearrangements, has become a diagnostic tool widely used in the investigation of B-cell lymphomas, but the overall sensitivity of these methods does not exceed 80%, notably in germinal center (GC) and post-GC B-cell origin lymphomas. Many PCR strategies devised for detecting immunoglobulin light chain (IgL) gene rearrangements have been developed to enhance the clonality detection rates. However, the feasibility of these methods in routine clinical diagnosis using paraffin-embedded tissues has not yet been investigated sufficiently. We studied a large series of 108 cases of B-cell lymphomas, as well as 20 reactive lymphoid tissues using degenerate primers to amplify immunoglobulin kappa (Igkappa) and lambda (Iglambda) light chain genes. B-cell clonality was further investigated using semi-nested PCR for IgH gene rearrangements. B-cell clonality was detected in 74%, 56.5%, and 43.5% of cases using IgH, Igkappa, and Iglambda PCR, respectively. By combining these methods, the clonality detection rate increased to 93.5%. Only polyclonal patterns were noted in reactive lymphoid samples. We concluded that in addition to the established methods for IgH analysis, a PCR-based approach for IgL gene rearrangements analysis improves the clonality detection rate in over 90% of B-cell lymphoma cases using routine histological specimens with poor preservation of the genomic DNA.