Noncycling state of peripheral blood progenitor cells mobilized by granulocyte colony-stimulating factor and other cytokines

Incubation with high doses of tritiated thymidine in vitro was used to determine the percent of progenitor cells in the S phase of the cell cycle. Peripheral blood (PB), bone marrow (BM), and spleen populations from mice injected with granulocyte colony-stimulating factor (G-CSF) at 5 micrograms/day for 5 days and BM cells from uninjected littermates were assayed. Although the percentage of progenitor cells in S phase in the marrow (47% +/- 5%) and spleen (52% +/- 9%) was increased significantly in G-CSF-treated mice, only a small proportion of PB progenitor cells (PBPC) were in S phase (7% +/- 4%). In normal human subjects injected with G-CSF at 5 or 10 micrograms/kg/d, the proportions of PB myeloid (-1 +/- 4%) and erythroid (0% +/- 8%) progenitor cells in S phase were very low compared with the proportion of myeloid progenitor cells in S phase in normal BM (34% +/- 10%). Similarly, the large majority of steady-state PBPC and PBPC mobilized by interleukin-3 in combination with either granulocyte-macrophage colony-stimulating factor or G-CSF were also found not to be in S phase. Experiments indicated that the low percentages of PBPC in S phase were not ascribable either to inhibitory elements in the blood or to reduced responsiveness to growth factors.     

Effect of phototherapy on thyroid stimulatory hormone and free thyroxine levels

Objective : To study the effect of phototherapy for neonatal hyperbilirubinaemia on thyroid function as neonatal thyroid screening is sometimes performed during exposure to phototherapy. Methodology : Infants with non-haemolytic hyperbilirubinaemia were sequentially allocated to fibre-optic phototherapy, conventional daylight phototherapy, or a combination of both. Bilirubin concentration was monitored 12 hourly by capillary blood sampling; venous blood was sampled for thyroid stimulating hormone (TSH) and free thyroxine (fT₄) determinations, at start of exposure, at 24 h, end of exposure and 1 day later. Comparable unexposed infants served as controls. Results : All 123 study infants and 25 controls remained well during the study. Bilirubin levels declined during phototherapy, being most rapid in the combination group. The TSH and fT₄ values at start of exposure were 3.86 ± 0.41 mU/L (mean ± SEM) and 33.20 ± 1.16 pmol/L, respectively, in the fibre-optic group, 3.62 ± 0.38 mU/L and 37.22 ± 1.76 pmol/L in the daylight group, and 4.40 ± 0.48 mU/L and 29.91 ± 1.13 pmol/L in the combined group, compared with 5.77 ± 0.40 mU/L and 34.46 ± 1.68 pmol/L in the control group. The TSH and fT₄ values declined with increasing age in the phototherapy and control groups with end of exposure values of 2.90 ± 0.28mU/L and 27.71 ± 0.71 pmol/L, 2.77 ± 0.31 mU/L and 33.52 ± 1.22pmol/L, and 3.44 ± 0.30 mU/L and 27.54 ± 0.88 pmol/L, respectively, compared with 4.21 ± 0.61 mU/L and 27.19 ± 2.33 pmol/L (at 72 h) in the control group. The pattern of TSH and fT₄ decline in the exposed and control groups was similar, being related to increasing age. Conclusions : The validity of neonatal thyroid screening is not affected by fibre-optic or conventional phototherapy or by both combined.     

Effect of the introduction of a financial incentive for fee-paying A&E attenders to consult their general practitioner before attending the A&E department

BACKGROUND: The Health (Out-Patient Charges) Regulations 1994 were designed to encourage those Irish patients liable for their own health care costs to attend their GP before their local Accident and Emergency (A&E) department. Such patients are referred to as General Medical Services (GMS)-ineligible. Prior to the introduction of the regulations in March 1994, there was a perverse financial incentive for these patients to attend directly A&E departments instead of their GP. OBJECTIVE: The aim was to compare the number of GMS-ineligible patients referred by a GP during the year before and the year after the implementation of the Regulations. METHOD: This study involved the audit of all new attendances to a large A&E department, for 1 year before and after the introduction of the new regulations. The main outcome measures were the number of new attenders in the subsequent year, the proportion of GMS-ineligible attenders, the proportion of GMS- ineligible attenders referred by a GP and the proportion of GMS- ineligible attenders referred by a GP and categorized as having neither critical nor urgent complaints. RESULTS: The total number of new attenders in the year subsequent to the introduction of the regulations was 45,302, an increase of 4.9% on the previous year's total. The proportion of GMS-ineligible attenders decreased from 45.3 to 44% (- 1.3%; 95% confidence interval (CI) -0.6 to -1.9). The proportion of GMS- ineligible attenders who were referred by a GP increased by 2.4% (95%; CI 1.7-3.1). The proportion of GMS-ineligible attenders, referred by a GP with complaints categorized as neither critical nor urgent, increased by 2.5% (95%; CI 1.8-3.2). CONCLUSIONS: The introduction of the regulations was associated with a small, but statistically significant, reduction in the number of GMS-ineligible patients who attended with non-emergency conditions. The proportion of GMS- ineligible attenders who were referred by a GP increased by 2.4% (95%; CI 1.7-3.1). The overall workload of the A&E department was, however, unaffected. Further evaluation of the effects of this reduction on the health status of patients is required.      

Estimation of cell survival by flow cytometric quantification of fluorescein diacetate/propidium iodide viable cell number

We report a flow cytometric method to quantify the number of viable cells remaining in suspension culture following exposure to cytotoxic drugs. Cell viability is assessed by flow cytometric measurement of cellular fluorescence after staining with fluorescein diacetate and propidium iodide in isotonic solution. The number of viable cells per ml of culture is determined by a timed count of viable cells and from knowledge of the flow cytometer sample flow rate. P388 murine or HL-60 human leukemia cells in culture were used as model systems. This method can quantify accurately viable cell concentrations in suspension culture from 100 cells/ml to 1 million cells/ml. The sensitivity of the method as a cytotoxicity assay increases if, following brief (1-4-h) exposure to drug, greater time is allowed for cell death and lysis to occur prior to flow cytometric counting of viable cells. If the viability assessment is deferred for at least 72 h following drug (daunorubicin, actinomycin D, vincristine) exposure, results were obtained approximating those obtained from the soft agar clonogenic assay or the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In studying the cytotoxic effects of vincristine, actinomycin D, 1-beta-D-arabinofuranosylcytosine, and daunorubicin on P388 or HL-60 cells sensitive and resistant to these agents, reasonable results were obtained by flow cytometric counting of viable cell number. We have been able to perform this flow cytometric viability assay with ease using bone marrow blast cells obtained from patients with acute myelogenous leukemia. The method is facile, relatively rapid, and since it is ideal for studying cells in suspension culture, its potential as a predictor of chemotherapeutic response in leukemia warrants further evaluation.     

Platelet-associated IgG in patients with lymphoma

Levels of platelet-associated IgG (PA-IgG) were studied in 72 patients with Hodgkin's (HD) and non-Hodgkin's lymphoma (NHL). Thirty-nine percent of patients with HD and 20% of patients with NHL had elevated PA-IgG levels. There was a positive correlation between disease activity and the presence of PA-IgG in HD and NHL. In patients with HD, PA-IgG strongly correlated with extent of disease and may serve as a marker of disease activity. PA-IgG may have facilitated platelet destruction in 5 of 11 thrombocytopenic patients with HD and increased PA-IgG and in 2 patients with HD and increased PA-IgG who developed severe thrombocytopenia when treated with chemotherapy.     

Autoantibodies to Tamm-Horsfall protein in detection of vesicoureteric reflux and kidney scarring

Measurement of IgG antibodies to Tamm-Horsfall protein (ATHA) in 92 bacteriuric schoolgirls aged 5-12 did not show a significant rise compared with the titres found in the sera of 24 healthy controls. ATHA titres showed no correlation with the presence of vesicoureteric reflux or kidney scarring and it is concluded that measurement of serum ATHA is of no value as a screening procedure for the detection of vesicoureteric reflux.