Effects of IgM Allotype Suppression on Serum IgM Levels,B-1 and B-2 Cells,and Antibody Responses ir Allotype Heterozygous F1 Mice

IgM allotype heterozygous F1 mice were independently suppressed for Igh6a or Igh6b to evaluate the contribution of B-1 and B-2 cells to natural serum IgM levels and Ab responses. B-2 B cells expressing IgM of the suppressed allotype were evident in the spleens of suppressed mice 4 to 6 weeks after cessation of the suppression regimen, whereas B-1 B cells of the suppressed allotype were undetectable for up to 9 months. Although serum IgM of the suppressed allotype was initially depleted in mice suppressed for either allotype, by 7 months of age, there were detectable levels of IgM of the suppressed allotype in the serum; however, the levels were significantly below that found in nonsuppressed mice. When mice were immunized with either the T-independent or T-dependent form of phosphorylcholine, those suppressed for either allotype, and consequently depleted of B-1 B cells of that allotype, did not respond with phosphorylcholine-specific IgM of the suppressed allotype. In contrast, when mice were immunized with α1-3 dextran, the Igh6a allotype-suppressed mice were able to produce dextran-specific IgM of that allotype. These results show that allotype-bearing B-1 cells of both allotypes can be effectively suppressed by this suppression protocol and this produces long-lasting effects on B-1 cell levels and serum IgM of the suppressed allotype. These observations reflect the derivation of the majority of B-1 cells from fetal-neonatal precursors, which cannot be replaced by newly emerging B-2 cells of adult origin. Their ablation by antibody treatment results in permanent alterations to the adult B-cell repertoire.     

Breastfeeding Preterm Twins: A Case Report

ABSTRACT: This case report describes a primipara who successfully breastfed 35-week-gestation twins for over six months. Positive interactions, research-based management strategies, and innovative problem solving helped her avoid the individual, interpersonal, and system factors that can injuence lactation failure. (BIRTH 21:2, June 1994)     

Identification of a protein factor secreted by 3T3-L1 preadipocytes inhibitory for the human MCF-7 breast cancer cell line.

The 3T3-L1 cell line is a preadipocyte cell line derived from the Swiss 3T3 mouse fibroblast cell line. We have compared the effect of 3T3-L1 conditioned medium (3T3-L1 CM) and Swiss 3T3 conditioned medium (3T3 CM) on the growth of normal mouse mammary cells (NMMG) and the human MCF-7 breast carcinoma cell line. 3T3 CM increased the growth of both NMMG and MCF-7 cells by 19 +/- 2% (SD) and 24 +/- 3%, respectively, and increased thymidine incorporation by 74 +/- 4% and 104 +/- 8%, respectively. Conditioned medium from 3T3-L1 cells stimulated the growth of NMMG cells by 64 +/- 2%; in contrast, 3T3-L1 CM inhibited the growth of MCF-7 cells by 36 +/- 1%. In parallel with these growth studies, thymidine incorporation increased by 20 +/- 4% in NMMG cells and decreased by 72 +/- 5% in the MCF-7 cells. Moreover, a similar effect was also noted in NCI H630 colon cancer cells, where 3T3-L1 CM produced a 58 +/- 4% decrease in growth and a 82 +/- 6% decrease in thymidine incorporation. Heating the 3T3-L1 CM at 100 degrees C for 30 min destroyed all inhibitory activity. Several known inhibitory growth factors (fibroblast growth factor, 20 ng/ml; interleukin 6, 1000 units/ml; tumor necrosis factor alpha, 15 ng/ml; transforming growth factor beta, 1 ng/ml) were tested for activity in the MCF-7 cells. Tumor necrosis factor alpha and transforming growth factor beta produced a 97% and 67% inhibition of thymidine uptake, respectively, whereas interleukin 6 and fibroblast growth factor had no effect. Neither transforming growth factor beta nor tumor necrosis factor alpha activity was detectable in 3T3-L1 CM using an enzyme-linked immunosorbent assay. High-performance liquid chromatography fractionation of the 3T3-L1 CM revealed that the inhibitory activity eluted at a molecular weight of 67,000; moreover, silver staining of these eluates on a denaturing polyacrylamide gel revealed that M(r) 69,000 peptide was the predominant protein band in the inhibitory fractions. Thus 3T3-L1 CM stimulates the growth of normal breast epithelial cells and inhibits the growth of MCF-7 breast cancer cells. This inhibitory activity appears to be due to a protein secreted by 3T3-L1 preadipocytes.     

Invasive ventilation in the emergency department: Part 2: Implications for patient safety

The use of mechanical ventilation in the Emergency Department requires adequate resources in order to maintain patient safety and avoid potential risks. Moreover, developments in technology require increased knowledge of mechanical ventilation techniques to address the complexity of decision-making involved. Organisational issues and system factors have the potential to negatively impact on the ability of the emergency service to provide optimum care to patients receiving mechanical ventilation. These issues include staffing and skill-mix, demand on emergency services, role-delineation, scope of practice, and current mechanisms for monitoring of quality and safety. Furthermore, in response to advances in ventilator technology, current education programs for both nursing and medical staff require review to ensure that they provide comprehensive information about the types of ventilation techniques now available and the relative risks and benefits associated with their application.This article is the second in a two-part series and explores the educational and organisational factors that impact upon safety and quality of care delivered to patients receiving mechanical ventilation in the emergency department. Recommendations for future policy development, curriculum review and reporting mechanisms to support further research in the application of mechanical ventilation in the emergency department are made.     

Regional lipiodolized chemotherapy for cholangiocarcinoma associated with oral contraceptives

We describe a case of cholangiocarcinoma in a young woman, who presented with cholestatic jaundice following oral contraceptive ingestion. Following diagnostic laparotomy she received intra-arterial 'lipiodolized' chemotherapy. Intravenous mitozantrone was given for 2 years and she is asymptomatic, with computed tomographic evidence of tumour response, 27 months after diagnosis. We suggest that this form of treatment is of value for cholangiocarcinoma.