Design and testing of a centrifugal fluidic device for populating microarrays of spheroid cancer cell cultures

Background

In current cancer spheroid culturing methods, the transfer and histological processing of specimens grown in 96-well plates is a time consuming process. A centrifugal fluidic device was developed and tested for rapid extraction of spheroids from a 96-well plate and subsequent deposition into a molded agar receiver block. The deposited spheroids must be compact enough to fit into a standard histology cassette while also maintaining a highly planar arrangement. This size and planarity enable histological processing and sectioning of spheroids in a single section. The device attaches directly to a 96-well plate and uses a standard centrifuge to facilitate spheroid transfer. The agar block is then separated from the device and processed.

Results

Testing of the device was conducted using six full 96-well plates of fixed Pa14C pancreatic cancer spheroids. On average, 80% of spheroids were successfully transferred into the agar receiver block. Additionally, the planarity of the deposited spheroids was evaluated using confocal laser scanning microscopy. This revealed that, on average, the optimal section plane bisected individual spheroids within 27% of their mean radius. This shows that spheroids are largely deposited in a planar fashion. For rare cases where spheroids had a normalized distance to the plane greater than 1, the section plane either misses or captures a small cross section of the spheroid volume.

Conclusions

These results indicate that the proposed device is capable of a high capture success rate and high sample planarity, thus demonstrating the capabilities of the device to facilitate rapid histological evaluation of spheroids grown in standard 96-well plates. Planarity figures are likely to be improved by adjusting agar block handling prior to imaging to minimize deformation and better preserve the planarity of deposited spheroids. Additionally, investigation into media additives to reduce spheroid adhesion to 96-well plates would greatly increase the capture success rate of this device.

Innovation in catheter design for intra-arterial liver cancer treatments results in favorable particle-fluid dynamics

Background

Liver tumors are increasingly treated with radioembolization. Here, we present first evidence of catheter design effect on particle-fluid dynamics and downstream branch targeting during microsphere administrations.

Materials and methods

A total of 7 experiments were performed in a bench-top model of the hepatic arterial vasculature with recreated hemodynamics. Fluorescent microspheres and clinically used holmium microspheres were administered with a standard microcatheter (SMC) and an anti-reflux catheter (ARC) positioned at the same level along the longitudinal vessel axis. Catheter-related particle flow dynamics were analyzed by reviewing video recordings of UV-light illuminated fluorescent microsphere administrations. Downstream branch distribution was analyzed by quantification of collected microspheres in separate filters for two first-order branches. Mean deviation from a perfectly homogenous distribution (DHD) was used to compare the distribution homogeneity between catheter types.

Results

The SMC administrations demonstrated a random off-centered catheter position (in 71 % of experiments), and a laminar particle flow pattern with an inhomogeneous downstream branch distribution, dependent on catheter position and injection force. The ARC administrations demonstrated a fixed centro-luminal catheter position, and a turbulent particle flow pattern with a more consistent and homogenous downstream branch distribution. Quantitative analyses confirmed a significantly more homogeneous distribution with the ARC; the mean DHD was 40.85 % (IQR 22.76 %) for the SMC and 15.54 % (IQR 6.46 %) for the ARC (p = 0.047).

Conclusion

Catheter type has a significant impact on microsphere administrations in an in-vitro hepatic arterial model. A within-patient randomized controlled trial has been initiated to investigate clinical catheter-related effects during radioembolization treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0188-8) contains supplementary material, which is available to authorized users.

Evaluation of a novel atrial retractor for exposure of the mitral valve in a porcine model

OBJECTIVES

To describe a novel atrial retractor and compare 2 methods of intraoperative left atrial retraction for minimally invasive mitral valve repair.

METHODS

Left atrial retraction was performed on 5 swine cadavers to evaluate performance (percent of mitral valve annulus accessible), complications encountered, ease of use, and surgical time for the minimally invasive atrial retractor and a HeartPort atrial retractor.

RESULTS

Estimated accessibilities were 93.0% (standard error = 3.2) and 92.7% (standard error = 3.3) for the HeartPort and minimally invasive atrial retractor retractors, respectively, with a difference of 0.3% (standard error = 2.2%, P = .8832, df = 34). Tissue damage occurred in 1 case for the minimally invasive atrial retractor and 2 cases for the HeartPort retractor. The mean surgical times for retractor placement and mitral valve annulus exposure were 107.4 and 39.2 seconds for the HeartPort and minimally invasive atrial retractor retractors, respectively, with a difference of 68.2 seconds (P = .0092, df = 4).

CONCLUSIONS

The minimally invasive atrial retractor is a suitable alternative for atrial retraction compared with standard techniques of retraction. It provides comparable exposure of the mitral valve annulus, is less time consuming to place, provides subjectively more working volume within the left atrium, and has the advantage of minimal atriotomy incision length and customizable retraction.

Atypical teratoid/rhabdoid tumor of the spine

SUMMARY

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant central nervous system neoplasm usually seen in young children and infants. Prognosis for AT/RT is poor, with most patients dying within 1 year of presentation. AT/RT most commonly occurs intracranially. Location in the spine, though previously reported, is rare, and imaging findings have not been emphasized in the past. We present a case of AT/RT occurring in the thoracolumbar spine of a child and review available clinical and imaging findings in previously reported cases of spinal AT/RT.

Uteroplacental insufficiency affects epigenetic determinants of chromatin structure in brains of neonatal and juvenile IUGR rats

Intrauterine growth retardation (IUGR) increases the risk of neuroendocrine reprogramming. In the rat, IUGR leads to persistent changes in cerebral mRNA levels. This suggests lasting alterations in IUGR cerebral transcriptional regulation, which may result from changes in chromatin structure. Candidate nutritional triggers for these changes include altered cerebral zinc and one-carbon metabolite levels. We hypothesized that IUGR affects cerebral chromatin structure in neonatal and postnatal rat brains. Rats were rendered IUGR by bilateral uterine artery ligation; controls (Con) underwent sham surgery. At day of life 0 (d0), we measured cerebral DNA methylation, histone acetylation, expression of chromatin-affecting enzymes, and cerebral levels of one-carbon metabolites and zinc. At day of life 21 (d21), we measured cerebral DNA methylation and histone acetylation, as well as the caloric content of Con and IUGR rat breast milk. At d0, IUGR significantly decreased genome-wide and CpG island methylation, as well as increased histone 3 lysine 9 (H3/K9) and histone 3 lysine 14 (H3/K14) acetylation in the hippocampus and periventricular white matter, respectively. IUGR also decreased expression of the chromatin-affecting enzymes DNA methyltransferase 1 (DNMT1), methyl-CpG binding protein 2 (MeCP2), and histone deacetylase (HDAC)1 in association with increased cerebral levels of zinc. In d21 female IUGR rats, cerebral CpG DNA methylation remained lower, whereas H3/K9 and H3/K14 hyperacetylation persisted in hippocampus and white matter, respectively. In d21 male rats, IUGR decreased acetylation of H3/K9 and H3/K14 in these respective regions compared with controls. Despite these differences, caloric, fat, and protein content were similar in breast milk from Con and IUGR dams. We conclude that IUGR results in postnatal changes in cerebral chromatin structure and that these changes are sex specific.

Congenital heart defects and genetic variants in the methylenetetrahydroflate reductase gene

BACKGROUND

Most non-syndromic congenital heart defects (CHD) are caused by a complex interaction between maternal lifestyle factors, environmental exposures, and maternal and fetal genetic variants. Maternal periconceptional intake of folic acid containing vitamin supplements is reported to decrease the risk of CHD. The 677C-->T and 1298A-->C polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene decrease enzyme activity.

OBJECTIVE

To examine the relation between CHD and maternal and fetal MTHFR polymorphisms.

METHODS

375 nuclear families were studied. The transmission/disequilibrium test was used to test for transmission distortion in complete triads. A log-linear approach was used to test for associations between CHD and maternal and offspring polymorphisms, and to estimate independently the contributions of maternal and fetal variants to relative risks. Haplotype frequencies were estimated and a haplotype transmission disequilibrium test carried out.

RESULTS

The 1298C allele was transmitted less often than expected (p = 0.0013). There was no distortion in the transmission of the 677T allele, neither was there evidence of a parent of origin effect in the transmission of either of the single nucleotide polymorphisms. The 677C-1298C haplotype was also transmitted less often than expected (p = 0.0020). The relative risk associated with inheriting one copy of the 1298C allele was 0.64 (95% confidence interval, 0.48 to 0.87) and the that associated with inheriting two copies of the 1298C allele, 0.38 (0.21 to 0.70).

CONCLUSIONS

The apparent protective effect of the MTHFR 1298C allele against CHD could have several explanations and further study is needed.

Intracellular S-adenosylhomocysteine concentrations predict global DNA hypomethylation in tissues of methyl-deficient cystathionine beta-synthase heterozygous mice

Because S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are the substrate and product of essential methyltransferase reactions; the ratio of SAM:SAH is frequently used as an indicator of cellular methylation potential. However, it is not clear from the ratio whether substrate insufficiency, product inhibition or both are required to negatively affect cellular methylation capacity. A combined genetic and dietary approach was used to modulate intracellular concentrations of SAM and SAH. Wild-type (WT) or heterozygous cystathionine beta-synthase (CBS +/-) mice consumed a control or methyl-deficient diet for 24 wk. The independent and combined effect of genotype and diet on SAM, SAH and the SAM:SAH ratio were assessed in liver, kidney, brain and testes and were correlated with relative changes in tissue-specific global DNA methylation. The combined results from the different tissues indicated that a decrease in SAM alone was not sufficient to affect DNA methylation in this model, whereas an increase in SAH, either alone or associated with a decrease in SAM, was most consistently associated with DNA hypomethylation. A decrease in SAM:SAH ratio was predictive of reduced methylation capacity only when associated with an increase in SAH; a decrease in the SAM:SAH ratio due to SAM depletion alone was not sufficient to affect DNA methylation in this model. Plasma homocysteine levels were positively correlated with intracellular SAH levels in all tissues except kidney. These results support the possibility that plasma SAH concentrations may provide a sensitive biomarker for cellular methylation status.

Brief report: an empirically derived educational program for detecting and preventing skin cancer

College and high-school students were administered a questionnaire to assess their knowledge about skin cancer, and afterward an educational program was designed to correct the identified deficiencies. Results showed that the students were relatively uniformed about how to recognize and prevent skin cancer--high-school students more so than college students--but that their knowledge of the disease (e.g., risk factors, preventive measures, and identification of "warning signs" for early detection) increased significantly after training. Some forgetting was noted at a 2-week follow-up but knowledge levels were still significantly higher than baseline. If these findings are representative of the general population, more preventive education will be needed in this area. This is especially true because the potentially deadly melanoma appears to be increasing at an alarming rate.