Biosensor cell assay for measuring real-time aldosterone-induced release of histamine from mesenteric arteries.

AIMS: The aims were to develop a method for real-time detection of histamine release and to test whether incubation with aldosterone induces histamine release from isolated, perfused mice mesenteric arteries. METHODS: Fura-2-loaded HEK-293 cells transfected with the histamine H1 receptor was used as a sensitive biosensor assay for histamine release from isolated mouse mesenteric arteries. Activation of the H1 receptor by histamine was measured as an increased number of intracellular Ca2+ transient peaks using fluorescence imaging. RESULTS: The developed biosensor was sensitive to histamine in physiological relevant concentrations and responded to substances released by the artery preparation. Aldosterone treatment of mesenteric arteries from wild-type mice for 50 min resulted in an increased number of intracellular Ca2+ transient peaks in the biosensor cells, which was significantly inhibited by the histamine H1 blocker pyrilamine. Mesenteric arteries from mast cell-deficient SASH mice induced similar pyrilamine-sensitive Ca2+ transient response in the biosensor cells. Mesenteric arteries from wild-type and SASH mice expressed histamine decarboxylase mRNA, indicating that mast cells are not the only source of histamine release. CONCLUSION: The developed biosensor assay can measure release of substances from vascular preparations. Histamine is released from the vessel preparation in response to aldosterone treatment independently of mast cells. The assay enables us to study a new signaling mechanism for vascular responses induced by aldosterone.

The water channel AQP1 is expressed in human atherosclerotic vascular lesions and AQP1 deficiency augments angiotensin II-induced atherosclerosis in mice.

AIM: The water channel aquaporin 1 (AQP1) promotes endothelial cell migration. It was hypothesized that AQP1 promotes neovascularization and growth of atherosclerotic plaques. METHODS: AQP1 immunoreactivity and protein abundance was examined in human and murine atherosclerotic lesions and aortic aneurysms. Apolipoprotein E (ApoE) knockout (-/-) and AQP1-/-ApoE-/- mice were developed and fed Western diet (WD) for 8 and 16 weeks to accelerate the atherosclerosis process. In ApoE-/- and AQP1-/-ApoE-/- mice abdominal aortic aneurysms (AAA) were induced by angiotensin II (ANGII) infusion by osmotic minipumps for 4 weeks. RESULTS: In human atherosclerotic lesions and AAA, AQP1 immunoreactive protein was associated with intralesional small vessels. In ApoE-/- mouse aorta, APQ1 mRNA levels were increased with time on WD (n = 7-9, P < 0.003). Both in murine lesions at the aortic root and in the abdominal aortic aneurysmal wall, AQP1 immunoreactivity was associated with microvascular structures. The atherosclerotic lesion burden was enhanced significantly in ANGII-infused AQP1-/-ApoE-/- mice compared with ApoE-/- mice, but neither incidence nor progression of AAA was different. The aortic lesion burden increased with time on WD but was not different between ApoE-/- and AQP1-/-ApoE-/- mice at either 8 or 16 weeks (n = 13-15). Baseline blood pressure and ANGII-induced hypertension were not different between genotypes. CONCLUSION: AQP1 is expressed in atherosclerotic lesion neovasculature in human and mouse arteries and AQP1 deficiency augments lesion development in ANGII-promoted atherosclerosis in mice. Normal function of AQP1 affords cardiovascular protection.

P/Q-type and T-type voltage-gated calcium channels are involved in the contraction of mammary and brain blood vessels from hypertensive patients.

AIM: Calcium channel blockers are widely used in cardiovascular diseases. Besides L-type channels, T- and P/Q-type calcium channels are involved in the contraction of human renal blood vessels. It was hypothesized that T- and P/Q-type channels are involved in the contraction of human brain and mammary blood vessels. METHODS: Internal mammary arteries from bypass surgery patients and cerebral arterioles from patients with brain tumours with and without hypertension were tested in a myograph and perfusion set-up. PCR and immunohistochemistry were performed on isolated blood vessels. RESULTS: The P/Q-type antagonist ω-agatoxin IVA (10-8  mol L-1 ) and the T-type calcium blocker mibefradil (10-7  mol L-1 ) inhibited KCl depolarization-induced contraction in mammary arteries from hypertensive patients with no effect on blood vessels from normotensive patients. ω-Agatoxin IVA decreased contraction in cerebral arterioles from hypertensive patients. L-type blocker nifedipine abolished the contraction in mammary arteries. PCR analysis showed expression of P/Q-type (Cav 2.1), T-type (Cav 3.1 and Cav 3.2) and L-type (Cav 1.2) calcium channels in mammary and cerebral arteries. Immunohistochemical labelling of mammary and cerebral arteries revealed the presence of Cav 2.1 in endothelial and smooth muscle cells. Cav 3.1 was also detected in mammary arteries. CONCLUSION: P/Q- and T-type Cav are present in human internal mammary arteries and in cerebral penetrating arterioles. P/Q- and T-type calcium channels are involved in the contraction of mammary arteries from hypertensive patients but not from normotensive patients. Furthermore, in cerebral arterioles P/Q-type channels importance was restricted to hypertensive patients might lead to that T- and P/Q-type channels could be a new target in hypertensive patients.

Differential expression of T- and L-type voltage-dependent calcium channels in renal resistance vessels.

The distribution of voltage-dependent calcium channels in kidney pre- and postglomerular resistance vessels was determined at the molecular and functional levels. Reverse transcription-polymerase chain reaction analysis of microdissected rat preglomerular vessels and cultured smooth muscle cells showed coexpression of mRNAs for T-type subunits (Ca(V)3.1, Ca(V)3.2) and for an L-type subunit (Ca(V)1.2). The same expression pattern was observed in juxtamedullary efferent arterioles and outer medullary vasa recta. No calcium channel messages were detected in cortical efferent arterioles. Ca(V)1.2 protein was demonstrated by immunochemical labeling of rat preglomerular vasculature and juxtamedullary efferent arterioles and vasa recta. Cortical efferent arterioles were not immunopositive. Recordings of intracellular calcium concentration with digital fluorescence imaging microscopy showed a significant increase of calcium in response to K(+) (100 mmol/L) in isolated afferent arterioles (140+/-25%) and in juxtamedullary efferent arterioles (118+/-21%). These calcium responses were attenuated by the L-type antagonist calciseptine and by the T-type antagonist mibefradil. Intracellular calcium increased in response to K(+) in cortical efferent arterioles (21+/-9%). Mibefradil and nickel concentration dependently blocked K(+)-induced contraction of perfused rabbit afferent arterioles. Calciseptine blocked the contraction mediated by K(+) (EC(50) 8x10(-14)). S-(-)-Bay K 8644 had no effect on vascular diameter in the afferent arteriole. We conclude that voltage-dependent L- and T-type calcium channels are expressed and of functional significance in renal cortical preglomerular vessels, in juxtamedullary efferent arterioles, and in outer medullary vasa recta, but not in cortical efferent arterioles.

Vascular smooth muscle cells express the alpha(1A) subunit of a P-/Q-type voltage-dependent Ca(2+)Channel, and It is functionally important in renal afferent arterioles.

In the present study, we tested whether the alpha(1A) subunit, which encodes a neuronal isoform of voltage-dependent Ca(2+) channels (VDCCs) (P-/Q-type), was present and functional in vascular smooth muscle and renal resistance vessels. By reverse transcription-polymerase chain reaction and Southern blotting analysis, mRNA encoding the alpha(1A) subunit was detected in microdissected rat preglomerular vessels and vasa recta, in cultures of rat preglomerular vascular smooth muscle cells (VSMCs), and in cultured rat mesangial cells. With immunoblots, alpha(1A) subunit protein was demonstrated in rat aorta, brain, aortic smooth muscle cells (A7r5), VSMCs, and mesangial cells. Immunolabeling with an anti-alpha(1A) antibody was positive in acid-macerated, microdissected preglomerular vessels and in A7r5 cells. Patch-clamp experiments on aortic A7r5 cells showed 22+/-4% (n=6) inhibition of inward Ca(2+) current by omega-Agatoxin IVA (10(-8) mol/L), which in this concentration is a specific inhibitor of P-type VDCCs. Measurements of intracellular Ca(2+) in afferent arterioles with fluorescence-imaging microscopy showed 32+/-9% (n=10) inhibition of the K(+)-induced rise in Ca(2+) in the presence of 10(-8) mol/L omega-Agatoxin IVA. In microperfused rabbit afferent arterioles, omega-Agatoxin IVA inhibited depolarization-mediated contraction with an EC(50) of 10(-17) mol/L and complete blockade at 10(-14) mol/L. We conclude that the alpha(1A) subunit is expressed in VSMCs from renal preglomerular resistance vessels and aorta, as well as mesangial cells, and that P-type VDCCs contribute to Ca(2+) influx in aortic and renal VSMCs and are involved in depolarization-mediated contraction in renal afferent arterioles.

Rapid inhibition of vasoconstriction in renal afferent arterioles by aldosterone.

Aldosterone has been suggested to elicit vessel contraction via a nongenomic mechanism. We tested this proposal in microdissected, perfused rabbit renal afferent arterioles. Aldosterone had no effect on internal diameter in concentrations from 10(-10) to 10(-5) mol/L, but aldosterone abolished the ability of 100 mmol/L KCl to induce vascular contraction. The inhibitory effect of aldosterone was observed from 1 pmol/L. The inhibitory effect was significant after 5 minutes and maximal after 20 minutes and was fully reversible. Actinomycin D (10(-6) mol/L) prolonged the effect of aldosterone. The effect was abolished by the mineralocorticoid receptor antagonist spironolactone (10(-7) mol/L) but not by the glucocorticoid receptor antagonist mifepristone (10(-6) mol/L). The K+-mediated increase of intracellular calcium concentration in afferent arterioles was not affected by aldosterone. Mineralocorticoid receptor was detected by reverse transcription-polymerase chain reaction and immunohistochemistry in rat renal vasculature and rabbit endothelial cells. Inhibition of phosphatidylinositol (PI)-3 kinase with LY 294002 (3x10(-6) mol/L) restored sensitivity to K+ in the presence of aldosterone, and afferent arterioles were immunopositive for PI-3 kinase subunit p110alpha. Inhibition of NO formation by L-NAME (10(-4) mol/L) or inhibition of soluble guanylyl cyclase with 1H-(1,2,4)Oxadiazolo[4,3-a]quinoxaline-1-one restored K+-induced vasoreactivity in the presence of aldosterone. Similar to aldosterone, the NO donor sodium nitroprusside inhibited K+-induced vascular contraction. Geldanamycin (10(-6) mol/L), an inhibitor of heat shock protein 90, abolished aldosterone-induced vasorelaxation. We conclude that aldosterone inhibits depolarization-induced vasoconstriction in renal afferent arterioles by a rapid nongenomic mechanism that is initiated by mineralocorticoid receptor activation and involves PI-3 kinase, protein kinase B, and heat shock protein 90-mediated stimulation of NO generation.

CD34+ megakaryoblastic leukaemic cells are CD38-, but CD61+ and glycophorin A+: improved criteria for diagnosis of AML-M7?

The aim of this flow cytometry study in acute megakaryoblastic leukaemia (AML-M7) was to describe the membrane phenotype of CD34+ progenitor subsets and compare these with the phenotypes expressed by other AML FAB types. Following conventional histopathological diagnosis mononuclear cells from bone marrow and blood were examined in seven patients with AML-M7 and compared with results from 26 sequential patients with AML-M0 to AML-M6. The CD34+ subsets in AML-M7 patients differed from that of patients with AML-M0 to AML-M6 as the CD34+ CD61+ and the CD34+ Glycophorin A+ subsets were median 31% and 20%, respectively, compared to 4% and 2% in the AML-M0 to AML-M6 (P = 0.0005). Only 1% of the CD34+ progenitors were CD34+ CD38+ in AML-M7 compared to 72% in other AML subtypes (P < 0.000). These findings suggest that the CD34+ cell compartment in AML-M7 consists of early lineage-specific progenitors. In conclusion, flow cytometry analysis of CD34+ subsets may improve the diagnostic safety in AML-M7 and consequently the prognostic significance of immunophenotyping in acute leukaemia.

Priming with recombinant human hematopoietic cytokines before bone marrow harvest expands in vivo and enhances ex vivo recovery of myeloid progenitors in short-term liquid cultures.

BACKGROUND AND AIM: Short-term liquid marrow cultures (STLMC) are a potential source for autografting. We have previously shown that the quality of such grafts from transplantation candidates may be improved by hematopoietic cytokine support, especially if purified CD34-positive progenitors are cultured. The aim of this preclinical work was to quantitate ex vivo recovery of myeloid progenitors (colony-forming units-granulocyte/macrophage [CFU-GM]) in STLMC before and after short-term, in vivo treatment with recombinant human granulocyte colony-stimulating factor (rhG-CSF), granulocyte-macrophage colony-stimulating factor (rhGM-CSF), or interleukin-3 (rhIL-3). EXPERIMENTAL SETUP: Twenty-two sequential patients in marrow remission for hematological malignancies and eligible for autologous marrow transplantation received rhG-CSF or rhGM-CSF for 5 days or rhIL-3 for 10 days before marrow harvest. Marrow samples before and after in vivo priming were studied for CFU-GM in pre- and post-STLMC. RESULTS: After priming with rhG-CSF, rhGM-CSF, or rhIL-3, the number of isolated light-density cells increased nine-, six-, and two-fold, respectively. The total number of sampled (18 mL marrow) myeloid progenitors preculture (day 7/14 CFU-GM x 10(4) increased significantly from median 0.7/1.1 before to 37.3/26.7 after priming with rhG-CSF (n = 8) and from 5.6/3.4 before to 46.6/44.9 after priming with rhGM-CSF (n = 8) but remained unchanged (3.7/1.5 to 3.6/5.7) after priming with rhIL-3 (n = 6). The number of myeloid progenitors postculture (day 7/14 CFU-GM x 10(4) per 18 mL marrow) in cytokine-supported STLMC significantly increased from median 0.3/0.6 before to 7.0/5.3 after priming with rhG-CSF and from 1.9/1.6 before to 24.4/14.4 after priming with rhGM-CSF but remained unchanged (0.4/0.6 to 0.4/0.2) after priming with rhIL-3. Cytokine-primed and purified CD34+ marrow cells may be expanded in STLMC by a cytokine-driven differentiation into late myeloid progenitors and endstage cells. CONCLUSION: In vivo priming of bone marrow cells by hematopoietic cytokines significantly increases the recovery of harvested pre- and postculture myeloid progenitors. During cytokine-supported STLMC, early myeloid progenitors may differentiate into a "very late" progenitor pool with a potential for fast marrow regeneration. The number of such progenitors in cytokine-supported short-term liquid cultures may be sufficient for fast myeloid engraftment and complete peripheral blood or marrow stem-cell support after high-dose chemotherapy.

Chloride regulates afferent arteriolar contraction in response to depolarization.

-Renal vascular reactivity is influenced by the level of dietary salt intake. Recent in vitro data suggest that afferent arteriolar contractility is modulated by extracellular chloride. In the present study, we assessed the influence of chloride on K+-induced contraction in isolated perfused rabbit afferent arterioles. In 70% of vessels examined, K+-induced contraction was abolished by acute substitution of bath chloride. Consecutive addition of Cl- (30, 60, 80, 100, 110, and 117 mmol/L) restored the sensitivity to K+, and half-maximal response was observed at 82 mmol/L chloride. The calcium channel antagonist diltiazem (10(-6) mol/L) abolished K+-induced contractions. Bicarbonate did not modify the sensitivity to chloride. Norepinephrine (10(-6) mol/L) induced full contraction in depolarized vessels even in the absence of chloride. Iodide and nitrate were substituted for chloride with no inhibitory effect on K+-induced contraction. Approximately 30% of the vessels constricted in response to K+ in the absence of chloride. This response was reversibly blocked by the alpha1-blocker phentolamine (PA) (10(-5) mol/L) and, with PA present, the dependence on chloride was similar to the above series. The results show that K+-induced contraction of smooth muscle cells in the afferent arteriole is highly sensitive to chloride, whereas neurotransmitter release and ensuing contraction is not dependent on chloride. Thus, there are different activation pathways for depolarizing vasoconstrictors and for the sympathetic nervous system in renal afferent arterioles. This could be of physiological relevance for the resetting of afferent arteriolar sensitivity during changes in salt intake.

Reduction of digoxin-induced inotropism during quinidine administration.

A kinetic and dynamic study of digoxin was performed in 6 healthy subjects, and repeated in the same subjects after administration of quinidine for 1 wk. Myocardial performance evaluated by systolic time intervals increased in parallel with plasma digoxin concentration, whereas left ventricular end-diastolic diameter on echocardiography and arterial blood pressure remained constant. The positive inotropic effect of digoxin was abolished during concomitant treatment with quinidine. Quinidine has been reported to increase the risk of digitoxicity, and therefore the treatment with digoxin and quinidine in combination should be reconsidered.

Interactions between digoxin and potassium-sparing diuretics.

A kinetic and hemodynamic study of digoxin was performed in six healthy subjects and similar studies were performed during digoxin with spironolactone and with triamterene. Spironolactone reduced renal tubular secretion of digoxin and attenuated its positive inotropic effect (evaluated by systolic time intervals and echocardiography) and triamterene reduced the extrarenal elimination of digoxin, but induced no changes in digoxin-elicited inotrophy. It is suggested that the renal handling of digoxin is influenced by the intracellular potassium concentration in the renal tubular cell. The results indicate a drug-receptor interaction between spironolactone metabolites and digoxin at the hypothetical inotropic digitalis receptor. Amiloride has been reported to suppress digoxin inotropism, whereas spironolactone induces minor inhibition and triamterene does not affect digoxin inotropism.

Amiloride-induced changes in digoxin dynamics and kinetics: abolition of digoxin-induced inotropism with amiloride.

Digoxin dynamics and kinetics were studied in six healthy subjects with and without amiloride. Amiloride increased mean renal digoxin clearance from 1.3 to 2.4 ml . kg-1 . min-1 (p less than 0.001) due to increased tubular secretion of digoxin, while the glomerular filtration rate was unchanged. This might be caused by an increase in intracellular potassium concentration in the tubular cells provoked by amiloride. In contrast, the extrarenal clearance of digoxin was almost blocked by amiloride; it fell from a mean of 2.1 to 0.2 ml . kg-1 . min-1 (p less than 0.025). Total body clearance tended to fall, but the decrease was not statistically significant. EValuation of myocardial contractility by systolic time intervals revealed a concentration-response relationship between digoxin and changes in preejection period index when digoxin was given alone (rs = 0.750, p less than 0.001). Pretreatment with amiloride abolished this relationship (rs = 0.307, p = NS). Blood pressure and echocardiographically determined left ventricular end-diastolic diameter measurements indicated no changes in the left ventricular post- and preload. It is concluded that amiloride suppressed digoxin-induced inotropism.

Short-term in vivo priming of bone marrow haematopoiesis with rhG-CSF, rhGM-CSF or rhIL-3 before marrow harvest expands myelopoiesis but does not improve engraftment capability.

In an attempt to optimize bone marrow grafts for autologous transplantation 37 sequential patients suffering from various haematological diseases were treated with either recombinant human granulocyte colony-stimulating factor (rhG-CSF) (n = 23) or granulocyte-macrophage CSF (rhGM-CSF) (n = 8) for 5 days or interleukin 3 (rhIL-3) (n = 6) for 10 days before marrow harvest. All patients were in marrow remission at study entry. In contrast to rhIL-3, the administration of rhG-CSF or rhGM-CSF caused a significant (P < 0.01) increase in blood absolute neutrophil count. An increased marrow cellularity and a rise in the myeloid:-erythroid ratio was seen in the majority of patients during therapy, and in the rhIL-3 treated group a rise in the number of megakaryocytes and increased marrow fibrosis was seen in most patients. Moreover, a median of 2-, 5- and 10-fold increase in myeloid progenitors was the result of short-term administration of rhIL-3, rhGM-CSF and rhG-CSF, respectively. However, transplantation performed with primed expanded marrow grafts did not significantly reduce the time to myeloid regeneration when compared to historical controls. In conclusion, the results demonstrate that short-term priming with haematopoietic cytokines before autologous bone marrow stem cell harvest is a safe procedure which effectively expands marrow haematopoisis without enhanced engraftment capability.

Increased yield of myeloid progenitor cells in bone marrow harvested for autologous transplantation by pretreatment with recombinant human granulocyte-colony stimulating factor.

Pretreatment with haemopoietic cytokines prior to marrow harvest may result in improved quality of bone marrow harvested for autologous bone marrow transplantation (BMT). Such improvements may reduce the risk for graft failure and decrease time to engraftment. Patients undergoing autologous BMT received recombinant human G-CSF (rhG-CSF) immediately prior to marrow harvest. rhG-CSF was administered as daily subcutaneous injections for 5 days at 5 micrograms/kg body weight. Comparison of bone marrow samples before and after rhG-CSF treatment showed an increased bone marrow cellularity and a ninefold increase in the number of marrow leucocytes per volume aspirated. The mean marrow myeloid:erythroid ratio increased from 2.6 to 4.0. The mean numbers of immature (CD38 positive) and proliferating (CD71 positive) myeloid cells increased significantly from 41.6 to 50.8% and from 17.0 to 34.8%, respectively. Other subsets studied, including CD34 positive stem cells, were unchanged. The relative numbers of day 7 and 14 granulocyte-macrophage colony-forming units (day 7/14 GM-CFU) were unchanged. Long-term marrow cultures revealed that the numbers of 'long-term culture initiating cells' were unchanged after rhG-CSF treatment in spite of the ninefold increase in cellularity. To date, five of the patients have been transplanted with autologous marrow harvested after rhG-CSF treatment. Time to trilineage engraftment was unchanged compared with historical controls. We conclude that pretreatment with rhG-CSF prior to marrow harvest may improve the graft by increasing the total number of myeloid lineage restricted progenitor cells, resulting in stable but not accelerated myeloid engraftment of autologous marrow.

Hematopoietic growth factors for the treatment of myelodysplastic syndromes.

Administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF), rh granulocyte-macrophage colony-stimulating factor (rhGM-CSF) or rh interleukin-3 (rhIL-3) effectively stimulate and expand marrow myelopoiesis resulting in a dose-dependent increment of peripheral blood neutrophils in most patients with myelodysplasias (MDS). Clinical outcome with fewer infections have been reported in a few studies using rhG-CSF or rhGM-CSF, including a large randomized, controlled trial with rhGM-CSF. Clinical effective stimulation of megakaryopoiesis and erythropoiesis are however infrequent. Recently, rh erythropoietin (rhEpo) has been used to overcome the ineffective erythropoiesis in MDS to reduce transfusions needed. However, the efficiency has been low in most studies with marked differences in response rates. The most impressive clinical results were obtained in patients with milder forms of MDS combined with low prestudy endogenous S-Epo levels. The possible synergistic effect of combining rhEpo with rhG-CSF or rhGM-CSF has been studied with erythropoietic response rates of about 40%. The safety of the cytokine administration seems acceptable with no significant stimulation of leukemic myelopoiesis and subsequent progression into overt acute myeloid leukemia. In conclusion, combinations of hematopoietic growth factors may be of clinical benefit in some patients with MDS. However, due to the cost and unpredictable clinical outcome there is a need for extended laboratory research to understand the functional defects of MDS stem cells and progenitors.

Short-term rhG-CSF priming before chemotherapy does mobilize blood progenitors but does not prevent chemotherapy induced myelotoxicity: a randomized study of patients with non-Hodgkin's lymphomas.

The aim of this study was to evaluate the efficacy, safety and toxicity of short-term priming with recombinant human granulocyte colony-stimulating factor (rhG-CSF) immediately after diagnosis but before combination chemotherapy (CHOP) for non-Hodgkin's lymphomas. Of fourteen patients entering the study, seven received five days subcutaneous injection of rhG-CSF (5 micrograms/kg/day) before CHOP (CSF-group), and seven were treated with CHOP alone (control group). Blood samples were studied before and on days 1-5 during rhG-CSF priming as well as twice weekly after treatment. The number of blood and bone marrow progenitors was identified by clonogenic growth day 7, 14 and 21 of GM-CFU in semisolid medium. Blood absolute neutrophil counts increased in all rhG-CSF primed patients. The expansion of marrow myelopoiesis resulted in increased myeloid:erythroid ratios, increased bone marrow cellularity and increased numbers of myeloid progenitors both in the blood as well as the marrow. Chemotherapy induced neutropenia developed on day 9-12 in all patients independent of myeloid growth factor priming. However, neutropenia appeared earlier in the cytokine primed group (P = .0038). Five patients in the CSF-group and three patients in the control group were hospitalized with neutropenic fever, and septicemia was documented in three patients in the CSF-group. RhG-CSF induced expansion of myelopoiesis immediately before combination chemotherapy mobilized sufficient number of blood progenitors for apheresis but did not result in reduction of duration and degree of neutropenia in patients with newly diagnosed non-Hodgkin's lymphoma. Although the small number of patients prevents drawing definite conclusions, this time schedule for priming should be used with caution in the future due to an increased risk of hematologic toxicity.

Stimulation tests for the bone marrow neutrophil pool in malignancies.

It has been known for decades that blood neutrophilia occurs after the administration of etiocholanolone, adrenocortical steroids, and endotoxins. Neutrophil leukocytosis in general may be due to several mechanisms such as increased stimulation of the myelopoiesis, increased release from the marrow, a shift from the marginated to the circulating pool (demargination), prolongation in the peripheral half-life, and decreased migration of neutrophils from the blood to the tissue. However, the principal cause of the neutrocytosis for each of the above mentioned agents is increased release of neutrophils from the bone marrow reserves. Since a sufficient reserve capacity is a prerequisite for optimal defenses against infections, the marrow response has been used to estimate the dose of chemotherapy expected to be tolerated without life-threatening neutropenia. However, none of the above "test substances" have gained widespread use due to adverse reactions or undesirable effects on neutrophil function. Recent progress in biotechnology has developed recombinant human (rh) hematopoietic growth factors ready for clinical use. Marrow myelopoiesis is stimulated by granulocyte colony-stimulating factor (rhG-CSF) and granulocyte-macrophage CSF (rhGM-CSF). The immediate effect, however, is mobilization of mature neutrophil granulocytes to the blood. Bone marrow cellularity seems to influence the neutrophil number mobilized during 24 hours by one subcutaneous injection of either rhG-CSF or rhGM-CSF. A recent pilot study has suggested such a "24 hour stimulation test" to predict severe neutropenia following cyclic chemotherapy. This concept is illustrated by two case reports. The "stimulation test" suggests that we may devise strategies to define patient subsets which may benefit from prophylactic growth factor administration during cyclic chemotherapy.

Is the arterial switch operation still a challenge in small centers?

OBJECTIVE: In the last years, major changes as regards timing for operation, surgical technique, and perioperative care determined a great improvement in the arterial switch operation (ASO) allowing excellent mid-term results in a few leading centers. This stimulated the widespread adoption of ASO as procedure of choice for transposition of the great arteries (TGA), even in small institutions. We reviewed our early experience with ASO in an attempt to evaluate its safety in a small center. METHODS: Since April 1992, 39 consecutive patients underwent TGA repair by ASO in our department. There were 27 patients with simple TGA, 8 with TGA and VSD and 4 with Taussig-Bing heart and aortic coarctation. Median age and weight at operation were 7 days and 3.5 kg, respectively. Neonatal repair was performed in 34 patients. In accordance with the Planché coronary classification, type I was encountered in 21 patients, type II in 4 and type III in 14. Several modifications of the original technique were used, mainly regarding coronary relocation, pulmonary artery reconstruction and approaches for associated VSD closure and aortic arch repair. RESULTS: Early mortality was 2.6% (n = 1), the only operative death being related to unsatisfactory coronary relocation. Since modified ultrafiltration was adopted, mean ICU stay decreased from 5 +/- 4 days (n = 21) to 2 +/- 1 days (n = 17) (P < 0.05). Three patients required reoperation for residual ASD and/or VSD closure. There were no late deaths. After a mean follow-up of 26 +/- 15 months all survivors are thriving and are currently asymptomatic. CONCLUSIONS: Although this series is rather small, most of the major coronary anomalies and complex anatomic associations were encountered. This experience suggests that neonatal repair of TGA by ASO can be safely accomplished even in small centers. Modified ultrafiltration appears to improve the early outcome of neonates undergoing ASO.

Acute ethanol administration reduces the antidote effect of N-acetylcysteine after acetaminophen overdose in mice.

1. The combined antidote effect of N-acetylcysteine and ethanol on the toxicity of acetaminophen was investigated. 2. Fed male mice were given acetaminophen i.p. (600 mg kg-1) and after 5 min in addition ethanol i.p. (0.2 ml, 19% v/v), N-acetylcysteine i.p. (1.2 g kg-1, 0.2 ml), N-acetylcysteine + ethanol i.p. (same doses as given individually) or saline i.p. (0.4 ml). Survival rates were determined after 24, 48, 72 and 96 h. 3. In the N-acetylcysteine group the survival rate was 85%. This rate was significantly reduced to 43% in the N-acetylcysteine + ethanol group (P = 0.0001). In the groups given ethanol or saline alone only 7% and 3%, respectively, survived 96 h. 4. The data suggest that the protective effect of N-acetylcysteine on acetaminophen-induced toxicity in fed mice is reduced by concomitant administration of ethanol. This may explain the clinical observation that ingestion of ethanol worsens the prognosis after acetaminophen intoxication.

The treatment of fractures of the ring and little metacarpal necks. A prospective randomized study of three different types of treatment.

A total of 105 patients with fracture of the neck of the ring or little metacarpal bone were randomized to receive three different types of treatment: dorso-ulnar plaster-of-Paris from the proximal interphalangeal joint to elbow; functional brace around the wrist; or elastic bandage. Twenty patients (19%) had to be excluded for different reasons leaving 85 patients in the study. The remaining patients were examined after 4 weeks and 3 months. There was no difference in patient satisfaction between the three different types of treatment. The functional brace was in our opinion superior to the two other types of treatment: the patients had as little pain as the patients treated with plaster-of-Paris and less pain than patients treated with elastic bandage. Patients treated with a functional brace mobilized as fast as patients treated with elastic bandage and faster than patients treated with plaster-of-Paris. Based on these findings, we recommend the functional brace for treatment of fractures of the neck of the ring and little metacarpals.