Glucocorticoid-induced granulocytosis: contribution of marrow release and demargination of intravascular granulocytes

BACKGROUND: Glucocorticoid-induced granulocytosis has been attributed to enhanced release of polymorphonuclear leukocytes (PMNs) from bone marrow, delayed apoptosis, and reduced egress of PMNs into tissues. This study was designed to determine the relative contributions of PMNs released from the bone marrow and those entering the circulation from the marginated pool to the granulocytosis produced by a single dose of dexamethasone (2.0 mg/kg) in rabbits. METHODS AND RESULTS: PMN transit through the mitotic and postmitotic pools of the bone marrow and rate of release of PMNs into the circulation were measured by use of the thymidine analogue 5'-bromo-2'-deoxyuridine (BrdU) to pulse-label PMNs in the bone marrow. The shift of PMNs from the marginated to the circulating pool was measured with BrdU-labeled PMNs transferred from donor rabbits to recipients before dexamethasone was delivered. The data show that dexamethasone increased bone marrow release of PMNs and shortened their transit time through the postmitotic pool (P<0.001) but not the mitotic pool of the bone marrow (P>0.05). Dexamethasone slowed the clearance of BrdU-labeled PMNs from the circulation (P<0.05) and lengthened their disappearance (half-life) from the circulation compared with control (half-life, 4.95 versus 9. 45 hours). At 6 hours after dexamethasone, bone marrow release contributed approximately 10%, mobilization from the marginated pool approximately 61%, and a lengthened half-life in the circulation approximately 29% to the glucocorticoid-induced granulocytosis. CONCLUSIONS: We conclude that a single dose of dexamethasone causes a granulocytosis primarily by a shift of PMNs from the marginated to the circulating pool, with a minor contribution from marrow release.     

Strategies for prevention of infection in short-duration neutropenia

Although infection continues to be a major cause of morbidity and mortality in neutropenic patients, newer strategies have resulted in a shorter duration of neutropenia. The prime risk to patients with short-duration neutropenia (defined as neutropenia of less than 14 days) is bacterial infection, which is reduced by the administration of prophylactic antibiotics, and possibly by the use of clean food, sterile water, and protection against transmission of organisms from healthcare workers' hands.     

Enzyme induction by repeated adminstration of tetrachlorvinphos in rats

An automated method of sulfate analysis is described, which can detect sulfate concentrations as low as 2.5 mug per ml water. The assay is based on the reaction of sodium rhodizonate and barium forming a colored complex. Sulfate quantitavely interferes with this reaction. The assay is reproducible in the range of 2.5 to 30 mug sulfate per ml water. This method conveniently and accurately measures water soluble sulfate filtered from the air, and is especially useful in assaying samples containing microgram quantities of sulfate from experimental inhalation apparatus.     

Outpatient parenteral antibiotic therapy for fever and neutropenia

OPAT for osteomyelitis is effective, safe, and well-established. There are particular considerations with osteomyelitis, however, that relate to patient selection and the plans of therapy. Orthopedic infections may impose physical considerations that need to be considered. Concomitant medical problems, such as diabetes, must be considered and may be good reasons for hospital care aside from the infection. Further investigations of treatment of osteomyelitis are clearly needed, with OPAT patients being good subjects to study.     

Ornithine decarboxylase induction by glucocorticoids in brain and liver of adrenalectomized rats

Ornithine decarboxylase (ODC), the rate-limiting enzyme in the biosynthesis of polyamines, was measured in the brain and the liver of adrenalectomized rats after an acute s.c. treatment with glucocorticoids. The effects of corticosterone and dexamethasone were compared in three brain areas, the cerebral cortex, hippocampus, and cerebellum. These structures have similar concentrations of cytosolic glucocorticoid receptor, as measured by an in vitro exchange assay using a specific glucocorticoid ligand, [3H]RU 26988, but contain different amounts of mineralocorticoid receptor. Corticosterone and dexamethasone increased ODC activity in the liver and brain areas in a dose-dependent manner, dexamethasone being more active than corticosterone in all tissues. Moreover, estradiol, progesterone, and testosterone were inactive. Aldosterone, at high doses, increased brain ODC activity. Glucocorticoids, selected for their weak binding, or lack of binding to the mineralocorticoid receptor, were tested and found to be highly active in inducing brain and liver ODC, thus showing that ODC induction by steroids is specific for glucocorticoids. These results are among the first to suggest biochemically a central action of glucocorticoids following an acute treatment and confirm that the brain is a glucocorticoid target organ.     

Corticosteroid induction of threat-induced behavioral inhibition in preweanling rats.

Termination of ongoing behavior and assumption of defensive postures when threatened are adaptive characteristics of vertebrates. Altricial rat pups develop these characteristics by 14 days of age. At this time, pups inhibit their ultrasonic vocalizations and freeze when threatened. This emergence of behavioral inhibition is impaired when rats are adrenalectomized (ADX) at 10 days of age. That is, 14-day-old ADX pups exhibit deficits in freezing and continue to emit ultrasounds when confronted by an adult male rat. Studies also showed that removal of adrenal hormones does not potentiate vocalizations or render pups incapable of reducing their ultrasounds. More important, 3.0 mg/kg of corticosterone (CORT), but not lower doses, administered daily to ADX pups restored freezing, with lesser effects on ultrasound inhibition. Disrupting the developmental action of endogenous CORT appears to impair the ontogenic expression of behavioral inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

rhG-CSF treatment in cyclic neutropenia. Continuous versus intermittent rhG-CSF treatment in cyclic neutropenia

Cyclic neutropenia is a stem-cell disorder characterized by regular 21-day cyclic fluctuations in the number of neutrophils in the blood and bone marrow. The neutropenic periods may be complicated by fever, stomatitis and severe infections. In this case report only daily continuous and later intermittent treatment with recombinant human granulocyte colony-stimulating factor (two micrograms/kg) administered subcutaneously effectively prevented recurrent infections.     

Ciprofloxacin-induced neutropenia and erythema multiforme

Enrichment of soil with chitin (0.6%) significantly stimulated growth of chitinolytic microorganisms (the relative proportion was increased from 1.7 to 26.5%) and the formation of chitinase in soil. In a soil enriched with chitin and glucose (0.6%), the proportion of chitinolytic microorganisms remained similar to that in the nonenriched soil (1.4%), the enzyme formation was negatively affected.     

Requirement for two discrete stimuli for induction of the intestinal rapid expulsion response against Trichinella spiralis in rats

Rats subjected to a 7-day abbreviated enteral infection with Trichinella spiralis subsequently reject more than 90% of a challenge infection within 24 h. This process is known as rapid expulsion. In these experiments parabiotic rats were used to examine the factors that establish rapid expulsion in the intestine. Induction with low to moderate doses of worms required exposure to two separate stimuli. These initiated different responses; one was readily transferred between parabiotic rats, whereas the second response was sessile and restricted to the intestine. These two responses interacted synergistically to produce strong rapid expulsion. Stage-specific exposure of parabiotic rats to preadult or adult trichinae (or the unrelated parasite Heligmosomoides polygyrus) showed that only preadult worms induced the transferable factor. Exposure to adult worms or to H. polygyrus induced a strictly local intestinal effect that was nonspecific. It is suggested that preadult worms initiated an immune response specific for preadults. This was transferable between parabionts but was unable to produce rapid expulsion unless the intestine had been non-specifically stimulated. Intestinal stimulation is accomplished by exposure to adult worms in natural infections or artificial regimes. These results suggest novel techniques for the development of enteral antihelminth vaccines.     

Fever and neutropenia in children with malignant disease

Treatment of episodes of fever and neutropenia in pediatric hematology-oncology patients includes hospitalization and administration of intravenous antibiotics until the patient is afebrile and no longer neutropenic. The present analysis characterizes retrospectively febrile episodes in neutropenic pediatric hematology-oncology patients with regard to frequency of documented infections, organisms associated with these infections, efficacy of a standardized antibiotic regimen, and safety of early antibiotic discontinuation under defined conditions. A total of 149 pediatric febrile neutropenic episodes were identified during a 4-year period between 1990 and 1994. These occurred in 47 male and 19 female patients, of a mean age of 7.6 years (range 0.5-15). The most frequent diagnoses were leukemia (41% of patients), lymphoma (21%), rhabdomyosarcoma (7%), soft tissue sarcoma (5%), Ewing's sarcoma (5%), and osteosarcoma (4%). Infection was certain in 36% of febrile episodes, probable in 14%, and not determined in 50%. Patients with severe neutropenia (absolute neutrophil count < 100) had a slightly, although not significantly higher incidence of documented and probable infection (57%). Patients with solid tumor had documented infection in 40% of their febrile episodes, and the detection rate in the children with leukemia was 31% (P < .20) Blood cultures were positive in 21 (14%) of 149 episodes. Staphylococci (both coagulase-negative and coagulase-positive strains) and Pseudomonas were the organisms most frequently isolated (six episodes each). Mouth and throat (11), lungs (10), and skin (10) were the next most frequent sites of localized infection. Initial treatment consisted of piperacillin and amikacin or of vancomycin and amikacin when the source of fever was thought to be an infected central line catheter, with addition of amphotericin B by the seventh day of treatment when fever with neutropenia persisted or upon clinical suspicion of underlying fungal infection. There was a single fatality, of a patient with Burkitt's lymphoma. Antibiotics were discontinued when initial blood cultures had no growth after at least 48 hours and no source of infection was found, the blood count was improving, and if the patient became afebrile and clinically well. No patient needed readmission during the fortnight that followed discontinuation of antimicrobial therapy. Patients with negative blood cultures under defined conditions, as described above, could safely be discharged early, thus shortening the duration of intravenous antibiotic therapy and hospital stay.     

Early induction of alterations in cancellous and cortical bone histology after orchiectomy in mature rats

Androgen deficiency is associated with low bone mass in humans and animals, but the remodeling alterations that lead to bone loss are unclear. Our objective was to define early responses in both cancellous and cortical bone to orchiectomy (ORX) using histomorphometry in sexually mature (4-month-old) rats. A total of 62 male rats, 4 months of age, were divided into six groups, sham operated (SH) or orchiectomized (ORX), and sacrificed 1, 2, or 4 weeks after ORX. Calcein was given 5 and 2 days before sacrifice to label mineralizing surfaces. Bone mineral density (BMD) was measured in excised femurs by dual energy X-ray absorptiometry (DEXA). Static and dynamic histomorphometry was evaluated in the cancellous bone of the proximal tibial metaphysis and lumbar vertebral bodies, and in the cortical bone of the tibial diaphysis. Osteopenia began to develop by 2 weeks after ORX, though weight gain and femur length did not change. Femoral BMD was significantly reduced and BMC decreased (NS) by 4 weeks after ORX (p < 0.05). Tibial and vertebral cancellous bone volume decreased 19% and 13%, respectively, while osteoblast and osteoclast surfaces, and numbers of osteoclasts, increased after ORX. At 2 weeks post-ORX, an increase in cancellous bone formation rate was attributable primarily to an increase in mineralizing surfaces and a smaller rise in mineral apposition rate. In contrast, cortical bone periosteal, but not endosteal, bone formation rate and mineralizing surfaces decreased. We conclude that ORX stimulates cancellous and diminishes periosteal bone turnover rapidly after ORX, with subsequent decreases in bone volume and mineral density. The clear divergence in cortical and cancellous bone responses to hypogonadism raises important questions regarding the control of bone formation and its role in defining the skeletal phenotype.     

Hepatic and renal metallothionein induction following single oral administration of gallium arsenide in rats

Metallothionein genes (MT) are inducible by a variety of agents, including heavy metals. We report the induction of MT expression by gallium arsenide (GaAs), a superior intermetallic semiconductor material at two time intervals following single oral exposure in rats. The data is also supplemented with two additional groups exposed to gallium (III) as gallium oxide and arsenic (III) as sodium arsenite to determine which of the two moieties in GaAs is responsible for any such possible effects. The results indicate that GaAs administration does significantly induces MT in hepatic tissues accompanied by an increase in cytosolic glutathione, arsenic, zinc and copper concentration. It thus proves that arsenic moiety is chiefly responsible for such an effect.     

Corticosteroid induction of renal and intestinal K(+)-dependent p-nitrophenylphosphatase in young and adult rats

The post-natal development of the K(+)-dependent p-nitrophenylphosphatase (K-NPPase) activity of the Na, K-ATPase complex and its regulation by corticosteroids was studied in renal and intestinal epithelia of the rat using the p-nitrophenylphosphatecerium capture method. The distribution of the phosphatase was analysed in detail in the renal epithelia of the medullary thick ascending limb of Henle's loop and distal convoluted tubule and in the surface epithelial cells of the distal colon. The convoluted tubule and Henle's loop segments showed a stronger reaction for K-NPPase than the colon epithelium both in adult and young animals (suckling and weanling pups). The intensity of staining rose progressively in all three epithelia during early postnatal development and reached the highest levels during the weaning period and in adulthood. The most distinct change was observed between days 10 and 16. Adrenalectomy significantly reduced the density of the final reaction product in weanling and adult rats. Replacement hormone therapy of adrenalectomized weanling rats with the glucocorticoid dexamethasone restored the K-NPPase activity in the two renal epithelia, whereas the mineralocorticoid deoxycorticosterone acetate had no effect on the activity in the medullary thick ascending limb, a very slight effect in distal convoluted tubules, and a strong effect on the distal colon epithelial activity. The observed small effect of the mineralocorticoid in distal convoluted tubule activity may reflect a cross-over into glucocorticoid receptors. We conclude that the postnatal development of Na, K-ATPase is regulated by glucocorticoids in nephron epithelia and predominantly by mineralocorticoids in the surface enterocytes of the distal colon.     

An immunologic approach to induction of epidermal growth factor deficiency: induction and characterization of autoantibodies to epidermal growth factor in rats

The role of glutamate as a possible mediator of neurodegeneration is well described, and the homeostasis of extracellular glutamate is considered of major importance when addressing the pathogenesis of excitatory neurodegeneration. Applying the 'indicator diffusion' method to the microdialysis technique, we present a method that is suitable for the in vivo investigation of the capacity of cellular uptake of glutamate. Using 14C-mannitol as reference, we measured the cellular extraction and the cell membrane permeability of the test substance 3H-D-aspartate in the corpus striatum of the rat brain. The cellular extraction fraction of 3H-D-aspartate was 0.29, and the cell membrane permeability 2.24 x 10(-4) cm/s. In the presence of the glutamate-uptake blocker DL-threo-beta-hydroxyaspartate (THA) the extraction of 3H-D-aspartate was completely abolished, indicating that extraction of 3H-D-aspartate was due to cellular uptake by glutamate transporters. The cell membrane permeability towards 3H-D-aspartate was reduced by approximately 98% due to THA, indicating that the cell membranes per se are highly resistant to diffusion of 3H-D-aspartate. It is concluded that the present method can be used in studying the capacity of the glutamate transporters in vivo.     

Stomach adenocarcinoma induction in rats by the combined administration of N-methyl-N-nitroso-N'-nitroguanidine precursors

N-methyl-N'-nitroguanidine and sodium nitrite were administered as drinking water to non-inbred male rats at the level of Img/ml for over two years. Gastric adenocarcinomas were produced in 43.7% of rats surviving for 15.5 months when the first tumor was noticed. Gastric mucous membrane of other rats had morphological changes analogous to those induced by N-methyl-N-nitoroso-N'-nitroguanidine (MNNG). The results obtained indicate endogenous synthesis of MNNG from precursors in the stomach of rats.