Interleukin-3 treatment of rhesus monkeys leads to increased production of histamine-releasing cells that express interleukin-3 receptors at high levels

To understand the hematopoietic and nonhematopoietic responses to interleukin-3 (IL-3), expression of cell-surface IL-3 receptors (IL-3R) was examined on bone marrow (BM) cells and peripheral blood (PB) cells of rhesus monkeys during the course of in vivo IL-3 treatment. Whereas IL-3R expression is low in untreated monkeys, IL-3 administration led to a gradual increase in both low- and high-affinity binding sites for IL-3. This increase reflected the total number of cells expressing IL- 3Rs, as detected by flow cytometry using biotinylated IL-3. Most of these IL-3R+ cells in both BM and PB could be characterized as basophilic granulocytes that contained high levels of histamine. In contrast to the effect on these differentiated cells, IL-3 administration did not significantly alter the low level IL-3R expression on immature, CD34+ cells. Further flow cytometric analysis using biotinylated growth factors showed that the IL-3R+ basophils also expressed receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF), but not for IL-6 or Kit ligand. These findings indicated that the IL-3R+ cells included neither monocytes, which express GM-CSFRs and IL-6Rs abundantly, nor mast cells, which express c- kit. By combining flow cytometric and Scatchard data, it was calculated that the basophils contain as many as 1 to 2 x 10(3) high-affinity IL- 3Rs and 15 to 30 x 10(3) low-affinity sites. The finding that in vivo IL-3 treatment leads to the production of large numbers of cells that express high levels of IL-3R and are capable of producing histamine provides an explanation for the often severe allergic reactions that occur during prolonged IL-3 administration. It also indicates that IL- 3, in addition to its direct effects on hematopoietic cells, may also stimulate hematopoiesis through the release of secondary mediators such as histamine by IL-3-responsive mature cells.     

Differential use of endoplasmic reticulum membrane for phagocytosis in J774 macrophages

Sustained phagocytosis requires the continuous replacement of cell-surface membrane from intracellular sources. Depending on the nature of the engulfed particles, a variety of endocytic compartments have been demonstrated to contribute membranes needed for the formation of phagosomes. It has recently been reported that the endoplasmic reticulum (ER) can also fuse with the plasma membrane during phagocytosis [Gagnon, E., Duclos, S., Rondeau, C., Chevet, E., Cameron, P. H., Steele-Mortimer, O., Paiement, J., Bergeron, J. J. & Desjardins, M. (2002) Cell 110, 119-131]. However, there is currently no known mechanistic basis for this fusion process to occur. Here we report that direct ER-plasma membrane fusion during phagocytosis requires the ER resident soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein ERS24/Sec22b and that J774-macrophages react toward the challenge of large (3.0-microm) but not small (0.8-microm) particles by triggering this fusion mechanism, allowing them to access the most abundant endogenous membrane source in the cell, the ER.     

Emergency surgical revascularisation for coronary angioplasty complications.

OBJECTIVES--To evaluate trends in referrals for emergency operations after percutaneous transluminal coronary angioplasty (PTCA) complications; to analyse morbidity and mortality and assess the influence of PTCA backup on elective surgery. DESIGN--A retrospective analysis of patients requiring emergency surgical revascularisation within 24 hours of percutaneous transluminal coronary angioplasty. PATIENTS--Between January 1980 and December 1990, 75 patients requiring emergency surgery within 24 hours of percutaneous transluminal coronary angioplasty. SETTING--A tertiary referral centre and postgraduate teaching hospital. RESULTS--57 patients (76%) were men, the mean age was 55 (range 29-73) years, and 30 (40%) had had a previous myocardial infarction. Before PTCA, 68 (91%) had severe angina, 59 (79%) had multivessel disease, and six (8%) had a left ventricular ejection fraction of less than 40%. A mean of 2.1 grafts (range one to five) were performed; the internal mammary artery was used in only one patient. The operative mortality was 9% and inhospital mortality was 17%. There was a need for cardiac massage until bypass was established in 19 patients (25%): this was the most important outcome determinant (P = 0.0051) and was more common in those patients with multivessel disease (P = 0.0449) and in women (P = 0.0388). In 10 of the 19 cases a vacant operating theatre was unavailable, the operation being performed in the catheter laboratory or anaesthetic room. These 19 patients had an operative mortality of 32% and inhospital mortality of 47%, compared with 2% and 7% respectively for the 56 patients who awaited the next available operating theatre. Complications included myocardial infarction, 19 patients (25%); arrhythmias, 10 patients (3%); and gross neurological event, two patients (3%). The mean intensive care unit stay was 2.6 days (range 1 to 33 days) and the mean duration of hospital admission was 13 days (range 5-40 days). CONCLUSIONS--Patients undergoing emergency surgery after PTCA complications have a substantially increased inhospital mortality and morbidity. PTCA in this unit continues to require surgical cover. Delays in operating on stable patients in centres which operate a "next available theatre" backup policy may not differ from some units performing PTCA with offsite cover for PTCA complications. Particularly in the presence of multivessel disease, however, PTCA complications may be associated with the need for "crash" bypass and such patients are unlikely to survive hospital transfer. The proportion of patients requiring "crash" bypass has increased during the period reviewed because of the extent of disease in the emergency surgical group increased. These results indicate that surgery should not be denied to these patients.     

Estimation of expected number of rare alleles of a locus and calculation of mutation rate

An approach is described for the estimation of the number of rare variants in the population from the number in a sample drawn at random from the population. This quantity is used to derive an estimate of the mutation rate. The data required are the number of rare variants in the sample and the distribution of offspring within a population of well-defined size with little or no immigration. Application of this approach to data on 28 loci assayed in the Yanamamo, a tribe of South American Indians, yields an average mutation rate of 0.1 ~ 0.2 × 10^-5. Determination of this figure is subject to several assumptions concerning the nature of the rare variants and the structure of the population. Violation of these assumptions will generally result in the underestimate of the true mutation rate.     

Diagnostic role of an immunoassay-detected polymorphism of factor IX for potential carriers of hemophilia B

In hemophilia B, assays based on a monoclonal antifactor IX specific for the Thr-148 variant of an exonic polymorphism have diagnosed carriers in selected families by either establishing linkage or by indicating the presence or absence of a given normal factor IX. The sensitivity of the immunoassays for detecting heterozygous women was explored by comparing results from immunoassays with solid-phase polyclonal v the monoclonal antifactor IXs. Factor IX with the normal Ala-148 variant gave a flat dilution curve, qualitatively distinct from factor IX with the Thr-148 variant in the monoclonal assay. The two were indistinguishable in the polyclonal assay. Mixtures of equal amounts of the two types gave an intermediate result, about half as reactive in the monoclonal as compared with the polyclonal assay system. Whereas mixtures with 10% Ala-148 and 90% Thr-148 factor IXs could not readily be distinguished from Thr-148 factor IX plasma, as little as 1% of the Thr-148 protein was detected in Ala-148 factor IX plasma. The frequency of the Ala-148 variant varied in individuals with different ethnic backgrounds; it was found in 29% of white, 12% of black, and none of Asian blood donors' factor IX genes in Seattle. Only 4% of samples from South African black men were nonreactive (ie, Ala- 148). The Thr/Ala-148 dimorphism is in strong linkage disequilibrium with Taql restriction fragment length polymorphisms (RFLPs). Three recombinations were noted in normal white genes and one in a normal black factor IX gene (less than 2% of those examined). In 34 white families with at least one woman being a possible carrier, genetically, the immunoassay results were informative in 18. RFLP analyses were informative in eight of the 15 families tested. In five families each, assignment of carrier status was made to a woman by only DNA or only immunoassay results, whereas the other approach was noninformative. The immunoassays provide a rapid, inexpensive screening test and complement DNA analysis in white women who are potential carriers of hemophilia B.     

Lactate rise detected by 1H NMR in human visual cortex during physiologic stimulation.

Brain lactate concentration is usually assumed to be stable except when pathologic conditions cause a mismatch between glycolysis and respiration. Using newly developed 1H NMR spectroscopic techniques that allow measurement of lactate in vivo, we detected lactate elevations of 0.3-0.9 mM in human visual cortex during physiologic photic stimulation. The maximum rise appeared in the first few minutes; thereafter lactate concentration declined while stimulation continued. The results are consistent with a transient excess of glycolysis over respiration in the visual cortex, occurring as a normal response to stimulation in the physiologic range.     

Direct measurement of brain glucose concentrations in humans by 13C NMR spectroscopy.

Glucose is the main fuel for energy metabolism in the normal human brain. It is generally assumed that glucose transport into the brain is not rate-limiting for metabolism. Since brain glucose concentrations cannot be determined directly by radiotracer techniques, we used 13C NMR spectroscopy after infusing enriched D-[1-13C]glucose to measure brain glucose concentrations at euglycemia and at hyperglycemia (range, 4.5-12.1 mM) in six healthy children (13-16 years old). Brain glucose concentrations averaged 1.0 +/- 0.1 mumol/ml at euglycemia (4.7 +/- 0.3 mM plasma) and 1.8-2.7 mumol/ml at hyperglycemia (7.3-12.1 mM plasma). Michaelis-Menten parameters of transport were calculated to be Kt = 6.2 +/- 1.7 mM and Tmax = 1.2 +/- 0.1 mumol/g.min from the relationship between plasma and brain glucose concentrations. The brain glucose concentrations and transport constants are consistent with transport not being rate-limiting for resting brain metabolism at plasma levels greater than 3 mM.     

Pregnancy,birth and risk: an introduction

In this introduction, I use my nearly 40 years of work in the area to reflect on the total medicalisation of pregnancy and childbirth that informs even the critical sociology that purports to examine the issue. The risks that are faced in pregnancy and birth are not only the inherent dangers that midwives have worked with across time and space but also those particular risks introduced by medicalisation itself. Medicalisation blinds us to those risks on the one hand, while it blinds us to the skills and knowledge that midwives and birthing women themselves have on the other. The women and midwives researched in these articles show us that in pregnancy and birth, as in most of life, it is not just a matter of ‘real risk’ versus ‘perceived risk’ as risk theorists (too) often describe it. There is rather an intelligent balancing of risks, weighing of risks and contextualising of risks. What we see in this issue is a glimpse into the ways in which people intelligently, creatively and determinedly balance risks.