Isolation and high-dimensional flow cytometric analysis of tumor-infiltrating leukocytes in a mouse model of colorectal cancer

Colorectal cancer (CRC) is a complex and heterogeneous disease characterized by dysregulated interactions between tumor cells and the immune system. The tumor microenvironment plays a pivotal role in cancer initiation as well as progression, with myeloid immune cells such as dendritic cell and macrophage subsets playing diverse roles in cancer immunity. On one hand, they exert anti-tumor effects, but they can also contribute to tumor growth. The AOM/DSS colitis-associated cancer mouse model has emerged as a valuable tool to investigate inflammation-driven CRC. To understand the role of different leukocyte populations in tumor development, the preparation of single cell suspensions from tumors has become standard procedure for many types of cancer in recent years. However, in the case of AOM/DSS-induced colorectal tumors, this is still challenging and rarely described. For one, to be able to properly distinguish tumor-associated immune cells, separate processing of cancerous and surrounding colon tissue is essential. In addition, cell yield, due to the low tumor mass, viability, as well as preservation of cell surface epitopes are important for successful flow cytometric profiling of tumor-infiltrating leukocytes. Here we present a fast, simple, and economical step-by-step protocol for isolating colorectal tumor-associated leukocytes from AOM/DSS-treated mice. Furthermore, we demonstrate the feasibility of this protocol for high-dimensional flow cytometric identification of the different tumor-infiltrating leukocyte populations, with a specific focus on myeloid cell subsets.

AKT activity orchestrates marginal zone B cell development in mice and humans

The signals controlling marginal zone (MZ) and follicular (FO) B cell development remain incompletely understood. Here, we show that AKT orchestrates MZ B cell formation in mice and humans. Genetic models that increase AKT signaling in B cells or abolish its impact on FoxO transcription factors highlight the AKT-FoxO axis as an on-off switch for MZ B cell formation in mice. In humans, splenic immunoglobulin (Ig) D+CD27+ B cells, proposed as an MZ B cell equivalent, display higher AKT signaling than naive IgD+CD27- and memory IgD-CD27+ B cells and develop in an AKT-dependent manner from their precursors in vitro, underlining the conservation of this developmental pathway. Consistently, CD148 is identified as a receptor indicative of the level of AKT signaling in B cells, expressed at a higher level in MZ B cells than FO B cells in mice as well as humans.

Regionalization of infant transports: the southern California experience and its implications. I: Referral pattern

The development and implementation of neonatal intensive care services have been essential components of perinatal regionalization during the past two decades. The transport of critically ill infants to regional neonatal intensive care units has played an important role in improving neonatal outcome. This article presents a profile of Southern California's 10-year infant transport experience (1979 through 1988) in terms of the following indicators: transport volume, cross-county referrals, distance travelled, referral pattern, and birth weight pattern. Findings point to the necessity of focusing attention on several critical issues confronting Southern California's neonatal services in the 1990s. They include adequacy of tertiary or intermediate bed capacity in neonatal intensive care units; appropriateness of existing infant referral practices; impact of maternal-fetal transports; availability of financing resources; and overall differences in morbidity and mortality rates between transported and nontransported infants in subpopulations.

Comparison of neonatal mortality rates between transports to tertiary and intermediate neonatal intensive care units

The differential of neonatal mortality rates between infant transports to tertiary and to intermediate neonatal intensive care units (NICUs) was examined based on 8,391 one-time infant transports from community hospitals to tertiary or intermediate NICUs in Southern California in the three-year period 1981-1983. Among the demographic, birth and delivery, and diagnostic characteristics studied, nine were identified to be related significantly to the higher neonatal mortality rate among transports to tertiary NICUs: birthweight, gestational age, necessity of intubation, multiple clinical conditions, presence of cardiac, neurologic, and genitourinary problems, anomalies, and syndromes. Adjusting for differences in the number of cases with necessity of intubation and the presence of the five clinical problems reduced the neonatal mortality ratio of tertiary to intermediate NICUs from 1:56 to 1:01, while adjustment for birthweight and gestational age differences reduced the ratio from 1.56 to 1.54. This analysis indicates that the difference of neonatal mortality between the two levels of NICUs can be explained to a larger extent by the higher proportion of infants requiring intubation with serious clinical problems. Birthweight and gestational age played only a minor role in this respect.

Color Doppler imaging of intracranial vessels in the neonate

This study was performed to examine the effectiveness of color Doppler imaging (CDI) in demonstrating the neonatal intracranial vessels and altered intracranial flow patterns and to determine the optimal approach in imaging and intracranial vasculature. The study was conducted in two parts. First, 14 neonates were examined with CDI by using a standard approach through the anterior fontanel. Whenever possible, views through the posterior fontanel and the temporal bone were obtained also. The anterior cerebral, M1 segment of the middle cerebral, distal internal carotid, and basilar arteries were demonstrated consistently. Portions of the vertebral distal middle cerebral, and posterior cerebral arteries were frequently visualized. In the second part of the study, we examined 10 neonates who had undergone extracorporeal membrane oxygenation. In this group of patients, CDI was able to demonstrate occlusion of the right internal carotid artery and the reversal of flow through the ipsilateral A1 segment. Increased flow on the contralateral side and in the basilar artery was observed in several patients. The anterior fontanel approach was shown to be the most useful in identifying most of the major intracranial arteries and veins with CDI. In addition, the body weights and gestational ages of the neonates were found to significantly influence the success rate in visualizing the intracranial vasculature.

Impact of a regional infant dispatch center on neonatal mortality

In 1976, a regional Infant Medical Dispatch Center (IMDC) was implemented in Southern California to improve the lives and well-being of the critically ill newborn infants by expediting location of beds in neonatal intensive care units. Comparison of birth weight-specific neonatal mortality rates among 701-2000 grams neonates before and after the program showed a six-fold improvement in hospitals served by the Center over hospitals not served by the Center during the two-year period. From 1975 to 1977, a 43.7 per cent improvement in neonatal mortality among the 701-2000 grams neonates with hyaline membrane disease was observed in the transported infants served by the Infant Medical Dispatch Center as compared to a 22.9 per cent improvement in the group of transported infants not served by IMDC. Both indicators had consistently shown a marked improvement associated with the IMDC program beyond the improvement of medical sciences over the two years. The data suggest that the improved outcome of the neonates referred by IMDC might be related to the improved efficiency of locating available neonatal intensive care beds.

Evaluation of the FELMA microviscosimeter in predicting fetal lung maturity

A new, rapid technique for determining fetal lung maturity, the FELMA, was tested against the standard lecithin/sphingomyelin (L/S) ratio in predicting hyaline membrane disease (HMD). The FELMA was tested on 236 samples, 154 of which were compared with the L/S ratio; 102 neonates were delivered within 48 hours. There was a significant correlation between methods ( r = 0.47). No neonate with a mature FELMA score developed HMD. Of 5 neonates with HMD, 2 had mature L/S ratio in predicting lung immaturity, providing a rapid result without the necessity of thin-layer chromatography.