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At least 1,135 records · Page 63Linked to original sources
PubMed2005

[Effect of incremental cycling exercise performed before and 24 hours after blood withdrawal on the concentration of morphologic elements of blood in young health men].

The aim of this study was to evaluate the effect of incremental cycling exercise test performed before and 24 hours after blood donation (withdrawal of 450 ml of blood) on the plasma volume and concentration of morphologic elements of blood. Thirteen subjects (mean +/- SD), age 23 +/- 3 years; body mass 75 +/- 10 kg; BMI 23.4 +/- 2 kg x m(-2); VO2max 2903 +/- 334 ml x min(-1), volunteered for this study. The exercise test started at the power output of 20 W with an increase by 20 W every 3 minutes--until exhaustion. This test was performed once in the control study (7-12 days before blood donation) and repeated 24 hrs after blood donation. The blood samples were taken from the antecubital vein, in a sitting position (1) at rest, (2) at the stage of 100 W power output, (3) at the end of the test (the stage of exhaustion) and (4) at 2 hours after the end of the test. The changes in plasma volume were evaluated according to changes in hemoglobin and hematocrit concentrations. The significance of differences in the studied variables were tested using Wilcoxon test. At the end of the exercise test a significant (p<0.05) decrease in plasma volume was found in both study. It amounted to--11.1 +/- 2.9% in the control study, and to--13.0 +/- 3.9% after blood donation. Within 2 hours after the end of the exercise test plasma volume returned to the pre-exercise value in the control study and exceeded the pre-exercise value by 3.9 +/- 6.7% (p<0.05) in the study performed after blood donation. The MCV, MCH, and MCHC values were not affected by the exercise performed before and after blood donation. In the control study, at the end of the incremental exercise test a significant increase in the leukocyte, lymphocyte and thrombocyte count was found. At 2 hours after exercise thrombocytes count returned to the pre-exercise level, whereas the exercise-induced leucocytosis remained at the end-exercise level. The lymphocyte count decreased to lymphopenic level. During the incremental exercise test performed after blood donation the changes in the concentration of the studied morphologic elements of blood were similar as in the control study. The only difference was noticed in the changes of lymphocyte count which returned to the pre-exercise level within 2 hours after exhaustion. Taking into consideration the changes in plasma volume it was found that during the incremental exercise tests (both in the control study and after blood donation) there was a significant (p<0.05) extra vascular escape of erythrocytes and thrombocytes. This was accompanied by a significant accumulation of neutrophils and lymphocytes in circulating blood. At 2 hours after the end of exercise, neutrophils count increases and lymphocytes migrate into peripheral lymphoid tissues, causing lymphopenia.

Adult↗
PubMed2006

Using recombinant platelet-derived growth factor to facilitate wound healing.

Recombinant human platelet-derived growth factor (rhPDGF-BB) is a bioactive protein that has been combined with bone graft materials in an effort to regenerate the periodontium to its prediseased state more predictably. The combination of a biocompatible scaffold with this highly purified, recombinant human growth factor capitalizes on PDGF's stimulatory effects on cellular migration and proliferation, with subsequent matrix formation, to drive the healing process toward regeneration. When using a growth factor such as rhPDGF-BB with broad wound healing activity, an added clinical benefit is the more rapid soft tissue wound healing pattern observed at the surgical site. This also may be seen as a patient-centered benefit because it allows dentists to provide for a patient's prosthetic care on a timely basis, leading to a faster return to normal function. Also, the patient may resume plaque control efforts earlier, which further facilitates the wound-healing process. The purpose of these 2 case reports is to document the use of rhPDGF-BB as a wound-healing agent in 2 clinical situations and to provide a rationale for its use in this capacity.

Aged↗
PubMed1991

Oviductal vein resection affects pregnancy rates in sheep.

Progesterone is delivered locally via the oviductal vein to the cranial uterine horn ipsilateral to the ovary bearing the corpus luteum. Removal of the oviductal vein reduces this local delivery of progesterone. The objective of this experiment was to determine if local delivery of progesterone via the oviductal vein is necessary for embryo survival. Twenty-five nulliparous ewes were bred at estrus to fertile rams. On day 4 following breeding, ewes were randomly assigned to one of two treatment groups: oviductal vein resection (n = 11) or sham operated controls (n = 14). Following midventral laparotomy, the oviductal vein was isolated, ligated and removed. In the sham surgery control ewes, the oviductal vein was isolated, sutures were placed around the vein but were left unsecured. Following surgery, ewes were returned to the flock. Jugular venous blood samples were collected daily for 25 days after surgery and every third day until day 68 post breeding. On day 85 post breeding, ewes were laparotomized again to confirm pregnancy and location of the fetus. Blood samples were analyzed for progesterone via radioimmunoassay. The proportion of ewes pregnant in the oviductal vein resected groups were greater (p less than or equal to .08) than in the control, sham surgery group. Transuterine migration of embryos occurred in 2/4 pregnant, sham operated control ewes whereas migration occurred in 0/8 of the pregnant, oviductal vein resected ewes. Patterns of progesterone secretion differed (p less than or equal to .001) between pregnant and nonpregnant ewes across the entire sampling period. During maternal recognition of pregnancy, days 13 to 21 after breeding, overall mean jugular venous concentrations of progesterone were lower (p less than or equal to .05) in the oviductal vein resected ewes and patterns of secretion tended to differ (p less than or equal to .09) between oviductal vein resected and sham operated control ewes. It is concluded that oviductal vein resection increases pregnancy rates in nulliparous ewes and this may be due to a reduction in the local delivery of an inhibitor of embryo survival, possibly progesterone, or by maintaining the appropriate uterine environment conducive to a successful pregnancy.

Animals↗
PubMed1997

Rationale of a flexible press fit cup in total hip replacement. 5-year followup in 280 procedures.

A consecutive series of 280 total hip replacements in 261 patients using the Press Fit Cup with a minimum followup of 5 years is presented. The Press Fit Cup is a nonmodular acetabular component with a porous coating made of titanium fibers. It has one peg and is 1.5 mm oversized with biradial eccentricity. It has a flattened pole area, requires no screw fixation, and partially preserves elasticity. The mean age was 71 years for women, 70 years for men. Forty-seven patients (49 hips) died before the 5-year review, and five patients were unable to return for the followup because of physical infirmity. Two hundred eighteen patients (226 hips) were available for the clinical 5-year followup, and 208 patients (213 hips) were available for the radiographic followup. No intraoperative fracture of the acetabulum occurred; four hips dislocated; 94% clinically were rated as excellent or good. One hip in a patient with rheumatoid arthritis had to be revised for aseptic loosening of the cup and nine femoral stems had to be revised. No migration of the cup could be measured. There was no osteolysis seen around the cup. In six cases a radiolucent line was seen in Zone 1, and in eight hips in Zone 3. There was one hip with a continuous radiolucent line which was considered radiographically loose.

Adult↗
PubMed1988

Biliary and pancreatic secretory component of the migrating myoelectric complex in the pig. Effect on intraduodenal pH.

The aim of the present study in the pig was to describe the biliary and pancreatic secretory component of the migrating myoelectric complex (MMC) during the interdigestive period and after feeding, and to examine the effects of the extracorporal diversion of biliary or pancreatic secretions on the MMC and on the cyclical variation of intraduodenal pH. In a first trial six pigs (50.6 +/- 1.6 kg) were fitted with a permanent catheter in the common bile duct (3 pigs) or in the pancreatic duct (3 pigs) to control the flow of these secretions. They also had a duodenal catheter to return the secretions, and antral and duodenal electrodes for simultaneous recording of motility in fasting conditions. In a second trial ten pigs (50.8 +/- 1.5 kg) underwent a similar surgical preparation (5 bile duct and 5 pancreatic duct fistulations). They had, in addition, a duodenal T-shaped cannula (19 cm distal to the pylorus) allowing continuous intraluminal pH recording parallel to the motility recording. Experiments included 4 situations: secretions returned under fed or fasted conditions; by-passed secretions in fed or fasted pigs. The flow of bile and pancreatic juice was very high during irregular spiking activity phases (ISA), peaking at the beginning of regular spiking activity phases (RSA); it was minimal during quiescent phases. The duration of the duodenal MMC and of its 3 constitutive phases was not modified by total extracorporal diversion of bile or pancreatic secretion either in the fed or fasted state. During the interdigestive period the pH was significantly reduced under bile diversion (quiescence: 6.17 vs 7.15; ISA: 4.91 vs 5.94; RSA: 5.40 vs 6.52) as well as under pancreatic juice diversion (quiescence: 5.56 vs 7.18; ISA: 4.21 vs 5.97; RSA: 5.14 vs 6.72). In fed pigs only bile diversion resulted in a small acidification during the postprandial pattern (5.07 vs 5.44) and the consecutive MMC cycles (quiescence: 5.81 vs 6.61; ISA: 4.66 vs 4.92; RSA: 5.11 vs 5.78). Nevertheless the periodicity of pH variation along the MMC cycle was unaffected in bile or pancreatic juice-deprived animals. It is concluded that a true biliary and pancreatic secretory component of MMC exists in the pig, and that these 2 secretions strongly contribute to the neutralization of the duodenal contents. However, the major determinant of the cyclical variation of the intraduodenal pH appears to be the periodicity of the acid gastric outflow.

Animals↗
PubMed1993

Females have a larger hippocampus than males in the brood-parasitic brown-headed cowbird.

Females of the brood-parasitic brown-headed cowbird (Molothrus ater) search for host nests in which to lay their eggs. Females normally return to lay a single egg from one to several days after first locating a potential host nest and lay up to 40 eggs in a breeding season. Male brown-headed cowbirds do not assist females in locating nests. We predicted that the spatial abilities required to locate and return accurately to host nests may have produced a sex difference in the size of the hippocampal complex in cowbirds, in favor of females. The size of the hippocampal complex, relative to size of the telencephalon, was found to be greater in female than in male cowbirds. No sex difference was found in two closely related nonparasitic icterines, the red-winged blackbird (Agelaius phoeniceus) and the common grackle (Quiscalus quiscula). Other differences among these species in parental care, migration, foraging, and diet are unlikely to have produced the sex difference attributed to search for host nests by female cowbirds. This is one of few indications, in any species, of greater specialization for spatial ability in females and confirms that use of space, rather than sex, breeding system, or foraging behavior per se, can influence the relative size of the hippocampus.

Analysis of Variance↗
PubMed2003

Excess post-exercise oxygen consumption in adult sockeye (Oncorhynchus nerka) and coho (O. kisutch) salmon following critical speed swimming.

The present study measured the excess post-exercise oxygen cost (EPOC) following tests at critical swimming speed (Ucrit) in three stocks of adult, wild, Pacific salmon (Oncorhynchus sp.) and used EPOC to estimate the time required to return to their routine level of oxygen consumption (recovery time) and the total oxygen cost of swimming to Ucrit. Following exhaustion at Ucrit, recovery time was 42-78 min, depending upon the fish stock. The recovery times are several-fold shorter than previously reported for juvenile, hatchery-raised salmonids. EPOC varied fivefold among the fish stocks, being greatest for Gates Creek sockeye salmon (O. nerka), which was the salmon stock that had the longest in-river migration, experienced the warmest temperature and achieved the highest maximum oxygen consumption compared with the other salmon stocks that were studied. EPOC was related to Ucrit, which in turn was directly influenced by ambient test temperature. The non-aerobic cost of swimming to Ucrit was estimated to add an additional 21.4-50.5% to the oxygen consumption measured at Ucrit. While these non-aerobic contributions to swimming did not affect the minimum cost of transport, they were up to three times higher than the value used previously for an energetic model of salmon migration in the Fraser River, BC, Canada. As such, the underestimate of non-aerobic swimming costs may require a reevaluation of the importance of how in-river barriers like rapids and bypass facilities at dams, and year-to-year changes in river flows and temperatures, affect energy use and hence migration success.

Animal Migration↗
PubMed1983

Kinetics of Golgi apparatus membrane flux following monensin treatment of embryogenic carrot cells.

Ultrastructural changes resulting from treatment with the sodium selective ionophore, monensin, were studied in embryogenic suspension cultures of carrot, Daucus carota (L.) in the presence of 10 microM monensin, an early change in the Golgi apparatus was an increase in the number of cisternae per stack (dictyosome). An average of one additional cisterna per stack was formed within the first 2 to 4 min of monensin treatment; in some experiments a second cisterna was formed within about 8 min. Thereafter, large vacuoles began to appear in the cytoplasm adjacent to the Golgi apparatus with a return of the number of cisternae per dictyosomal stack to the control number of about 5. Cells treated comparable but in the absence of monensin showed no ultrastructural changes during the entire observation period. By 1 h of monensin treatment, the regions of the cells containing dictyosomes were populated by large number of vacuoles (up to 20 or more per electron microscope section). These vacuoles were interpreted as swollen dictyosome cisternae that separated from the stack but had not migrated from the Golgi apparatus zone in the monensin-treated cells. The results permitted an estimation of the average time for formation of a new dictyosome cisterna of 2 to 4 min. This range of values agreed with estimates for mammalian cells from short time labeling and turnover experiments of 3 to 4 min assuming a dynamic model for Golgi apparatus function in which cisternae are released from a maturing face and new cisternae are built up at an opposite or forming face.

Furans↗
PubMed1996

Morbidity and mortality surveillance in Rwandan refugees--Burundi and Zaire, 1994.

In April 1994, resumption of a longstanding conflict between the Hutus and Tutsis--the two major ethnic groups in the central African countries of Burundi and Zaire--resulted in civil war and mass genocide in Rwanda. An estimated 63,000 (primarily Tutsi) refugees subsequently moved from Rwanda into northern Burundi, and 500,000 refugees fled to Tanzania (Figure 1). In early July 1994, as armed strife subsided, many Tutsis returned home to Rwanda, and an estimated 1 million Rwandan Hutus fled to Zaire, and 170,000 fled to Burundi. To monitor the health status of the refugees, the Office of the United Nations High Commissioner for Refugees (UNHCR) and nongovernmental organizations (NGOs) working in refugee camps in both countries established systems for rapid surveillance of morbidity and mortality. This report presents the findings of these systems during May-September 1994 (the period of the most intensive population migration) and indicates that mortality was high among refugees in camps in both countries.

Burundi↗
PubMed1996

Corneal endothelial repair. Regulation of prostaglandin E2 synthesis.

PURPOSE: The authors have investigated the hypothesis that prostaglandin E2 (PGE2) synthesis is regulated during corneal endothelial wound healing. Previous studies have shown that PGE2 is an important mediator of endothelial mitosis, migration, and differentiation. METHODS: Biosynthesis of PGE2 was investigated in a wound closure model of the cultured rabbit corneal endothelium and in cultures treated with experimental agents. Prostaglandin E2 synthesis was measured by enzyme-linked immunosorbent assay. Pharmacologic experiments were designed to evaluate the contributions of protein kinases, phospholipase A2, and cyclooxygenase to endogenous PGE2 synthesis. RESULTS: Prostaglandin E2 synthesis is increased markedly in response to injury and is proportional to the extent of wounding. Biosynthesis of PGE2 returns to basal levels concurrently with recovery of the injury. Synthesis is dependent on the activities of protein kinase C (PKC), phospholipase A (PLA), and cyclooxygenase. Two forms of cyclooxygenase are present in corneal endothelial cells, and pharmacologic studies indicate that the activity of the COX 2 contributes to injury-dependent PGE2 synthesis. CONCLUSIONS: Prostaglandin E2 synthesis is increased in injured corneal endothelial cells. This synthesis is dependent on the coordinated regulation of PKC, PLA, and cyclooxygenase. Prostaglandin E2 synthesis presents an attractive target for pharmacologic manipulation of endothelial recovery from injury.

Animals↗
PubMed1988

[Immigration policies in Argentine law].

This paper analyzes contents of Argentine immigration laws in different periods of Argentine history and refers those contents to the State which enforced the corresponding immigration policies and to the socioeconomic structure they support. The Argentine constitution (1852) and subsequent immigration laws define 2 principal guidelines in population and immigration policies: 1) from 1852 until 1955 immigrants are seen as a part of socioeconomic growth, and 2) after 1955 the theory of national security prevails over considerations of an economic nature. With the return to democracy it should be possible to redefine immigration policies considering the country's demographic requirements and the migrants' own needs.

Americas↗
PubMed2005

Arthroscopic reconstruction of the acromioclavicular joint disruption: surgical technique and preliminary results.

INTRODUCTION: Numerous operative procedures have been described for the reconstruction of acromioclavicular joint separation; however, the arthroscopic reconstruction has been rarely reported. Therefore, our objective was to propose a new technique of arthroscopic acromioclavicular joint surgery and to evaluate the preliminary results. MATERIALS AND METHODS: Thirteen patients with a mean follow-up of 18 months underwent the arthroscopic acromioclavicular joint reconstruction using suture anchors and small titanium plate. The average age was 40.2 years (range 23-54 years). The shoulders were evaluated using Constant score and radiographs. The indications for surgery included acromioclavicular joint dislocation Rockwood type IV-V. RESULTS: Twelve patients returned to their work without pain within 3 months after operation. The average Constant score at last follow-up was 95. Postoperative radiographs confirmed anatomic reduction in ten patients, residual subluxation in two patients and redislocation of the joint in one patient. One patient had radiographic evidence of coracoclavicular ossification. All patients but one were satisfied with results and cosmetic appearance. CONCLUSION: Considering its less morbidity, excellent cosmesis, no need of hardware removal, and minimal complications from breakage or migration of metal implants, this new technique offers an attractive alternative in acromioclavicular joint stabilization.

Acromioclavicular Joint↗
PubMed1999

Expression of functional alpha7 nicotinic acetylcholine receptor during mammalian muscle development and denervation.

We have studied, on the transcriptional, protein and functional level, the expression of alpha7 nicotinic acetylcholine receptors (nAChR) in the course of rat muscle development, denervation and renervation. At foetal day 13, alpha7 nAChR expression was observed in somites and developing muscles of the back, but not yet in migrating myoblasts. Two days later, concomitant with myoblast aggregation, the alpha7 isoform began to be expressed in isolated myoblasts, with the highest level of expression in the frontal zone of the migrating wave. On foetal day 18, a time when the myoblasts in the upper hindleg have fused, alpha7 nAChR expression was most prominent in the outer layer of muscle tissue. The highest level of expression was observed in the first postnatal week, when practically all muscle cells stained positively for alpha7 protein. During the following weeks, alpha7 nAChR expression slowly decreased and practically disappeared in adult hindleg muscle. Following chronic denervation of adult Soleus muscle fibres, expression of alpha7 nAChR returned within 2-4 weeks. Electrophysiological measurements showed that the alpha7 nAChR of chronically denervated soleus muscle fibres were functional and, in particular, that they could be activated by choline. The presence of the alpha7 nAChR in developing and denervated muscle suggests a role for this nicotinic receptor in neuronal pathfinding and/or endplate stabilization.

Animals↗
PubMed1990

Cytokine regulation of IL-1 beta gene expression in the human polymorphonuclear leukocyte.

Although recently polymorphonuclear leukocytes (PMN) have been identified as producers of IL-1 beta in response to LPS and granulocyte/monocyte colony stimulating factor, little is known regarding the ability of other cytokines to induce the production of IL-1 beta in the PMN. Inasmuch as IL-1 and TNF have been shown to be important priming agents, as well as agents that induce migration of PMN, we investigated their effect on IL-1 beta gene expression in human peripheral blood PMN. In the present study, we demonstrate that human peripheral blood PMN produce IL-1 beta in response to IL-1 alpha, IL-1 beta, and TNF-alpha. Control (unstimulated) human PMN had virtually undetectable levels of IL-1 beta mRNA. Either IL-1 beta or TNF, induced PMN to transiently express IL-1 beta mRNA with peak expression at 1 h, returning to untreated levels by 2 h. A dose response indicated that as little as 0.05 ng/ml of IL-1 beta or TNF resulted in IL-1 beta induction, with maximal effects at 1 ng/ml of IL-1 beta and 5 ng/ml of TNF. IL-1 alpha or IL-1 beta exhibited similar dose responses in IL-1 beta mRNA induction. Inasmuch as cytokines have been shown to have synergistic effects in cell function studies, we induced PMN with a combination of maximally effective doses of TNF plus IL-1 beta. They demonstrated a cooperative effect on IL-1 beta gene expression, in that mRNA levels were sustained for three hours. IL-1 beta Ag expression, as measured by ELISA, paralleled IL-1 beta mRNA expression with cell associated peak levels at 2 to 4 h. IL-1 beta Ag levels in PMN lysates and supernatants correlated with IL-1 beta mRNA levels, i.e., TNF + IL-1 greater than TNF greater than IL-1. Thus, these studies represent the first demonstration of IL-1 and TNF induction of IL-1 beta gene expression in the PMN. Furthermore, the time course of induction is unique to the PMN, with peak induction of mRNA at 1 h, which is consistent with the short lived nature of these cells in inflammatory lesions.

Blotting, Northern↗
PubMed2003

Chemokines acting via CXCR2 and CXCR4 control the release of neutrophils from the bone marrow and their return following senescence.

In this study we provide evidence that the SDF-1alpha/CXCR4 chemokine axis is involved in both the retention of neutrophils within the bone marrow and the homing of senescent neutrophils back to the bone marrow. We show that the functional responses of freshly isolated human and murine neutrophils to CXCR2 chemokines are significantly attenuated by SDF-1alpha, acting via CXCR4. As a consequence, the mobilization of neutrophils from the bone marrow in vivo by the CXCR2-chemokine, KC, was dramatically enhanced by blocking the effects of endogenous SDF-1alpha using a specific CXCR4 antagonist. As neutrophils age, they upregulate expression of CXCR4 and acquire the ability to migrate toward SDF-1alpha. We show here that these senescent CXCR4(high) neutrophils preferentially home to the bone marrow in vivo in a CXCR4-dependent manner, suggesting a previously undefined mechanism for the clearance of senescent neutrophils from the circulation.

Animals↗
PubMed2004

Pubo-fascial versus vaginal sling operation for the treatment of stress urinary incontinence: a prospective study.

AIMS: To compare the long-term results of stress urinary incontinence (SUI) treatment involving the fascial or vaginal sling operations. MATERIAL AND METHODS: Two-hundred-thirty-two women were consecutively submitted to fascial or vaginal sling operations due to urodynamic proven SUI. The fascial group had a median age of 47.3 years with a parity of 2.2 and 1.8 surgeries/patient, while the vaginal group demonstrated a median age of 48.5 years with a median parity of 3.1 and 2.2 anterior surgeries/patient. The results were subjectively classified as cured--no further pads, greatly improved--very rare dribbling, improved--eventual dribbling necessitating one pad, no cure--with no urine loss change and worse. The number of pads/day, the presence of urgency or urge-incontinence episodes were all measured. Statistical analysis using Fisher's exact test was employed. RESULTS: The patients were followed up for an average time of 70.3 and 44.9 months, in the fascial and vaginal sling group respectively. Subjective clinical success rate was 93.7% for the fascial sling group and 79.8% for the vaginal one, however, the stratification of the results favored the fascial sling group mostly with 74.4% (94 cases) of the cases with total urinary control and no voiding dysfunctions. Only two cases (1.6%) in this group classified themselves as worsened. On the other hand, the vaginal sling subset revealed cure with total clinical satisfaction and no urinary complaint in 61.5% (62 females) (P > 0.05). Thirteen cases (12.5%) reported recurrence of the urine loss under stress and these constituted the failure group. The average number of pads diminished from 3.3 (+/- 0.8) to 0.2 (+/- 0.2) and from 3.2 (+/- 0.7) to 0.6 (+/- 0.5) after the surgery, for the fascial and vaginal sling operations respectively. Return to daily activities occurred after 9.3 days (+/- 1.2, max: 33, min: 2) for the fascial slings and 5.3 days (+/- 0.2, max: 17, min: 2) in the vaginal group. Surgical complications were compared between the groups. Time to urethral voiding varied according to expertise, demonstrating a diminishing tendency after the initial 20 cases. Female obstruction was observed in 11.1% of the fascial slings and 8.6% after vaginal approach, but none in the vaginal group required urethrolysis. Looking individually, the FS group migrated to the worse results while the VWS group started to lose the efficiency after 6 months. CONCLUSIONS: Sling operations are a safe and efficacious option to treat SUI, however, the results can vary according to the technique employed. Shorter efficacy and fewer complications are observed in vaginal wall sling operations, while durable results, but with a higher rate of voiding dysfunctions compromising the long-term clinical satisfaction may be observed after excessive urethral suspensions, as in fascial sling suspension.

Female↗
PubMed1990

Alpha-difluoromethylornithine resistance in Leishmania donovani is associated with increased ornithine decarboxylase activity.

The promastigote form of Leishmania donovani is sensitive to growth inhibition by DL-alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase (ODC), the first enzyme of the polyamine biosynthetic pathway, with an EC50 value of approximately 30 microM. Exposure of a wild type (DI700) cell population to gradually increasing concentrations of DFMO resulted in the selection of a strain of Leishmania, DFMO-10, which was capable of proliferating in 10 mM DFMO. DFMO-10 cells possessed an EC50 value for DFMO greater than 4 mM, and were cross-resistant to alpha-methylornithine, alpha-monofluoromethyl-3,4-dehydroornithine methyl ester, and delta-methyl-acetylenic putrescine, three other inhibitors of ODC activity. DI700 and DFMO-10 cells accumulated and/or transported [3H]DFMO and a spectrum of basic, neutral, and acidic amino acids at comparative rates. However, the DFMO-resistant Leishmania, if suspended in culture medium in the absence of DFMO for several days, expressed up to 15-fold greater levels of ODC activity than did wild-type cells. The overexpressed ODC in mutant cells appeared kinetically normal, since the ODC activities from DI700 and DFMO-10 cells possessed similar apparent Km values for ornithine and were equally sensitive to inactivation by DFMO. Incubation of extracts of DFMO-10 cells, but not of wild-type parental cells, with [3H]DFMO for 1 h resulted in the labeling of a polypeptide, presumably ODC, which migrated with a molecular weight of 76,000 +/- 4000 on SDS-gel electrophoretograms. As a consequence of the elevated ODC activities, the levels of putrescine in mutant cells released from DFMO exposure were also elevated by about 15-fold over those of wild-type cells, although spermidine levels in DI700 and DFMO-10 cells were similar. In the absence of prolonged selective pressure, the resistance to DFMO, the ODC activity, and the putrescine levels of DFMO-10 cells all returned to those of wild type cells, indicating that the mutant phenotype of DFMO-selected L. donovani was unstable.

Affinity Labels↗
PubMed2000

Osteoclasts differentiate from resident precursors in an in vivo model of synchronized resorption: a temporal and spatial study in rats.

Osteoclasts differentiate from mononucleated precursors expressing monocyte markers, which gradually evolve to preosteoclasts expressing the osteoclast phenotype. Although the role of osteogenic cells in these changes has been well documented in vitro, their contribution in vivo has not been established. In this study, a synchronized wave of resorption was activated along the mandibular periosteum. The periosteum adjacent to the bone surface studied was separated by a computer-assisted technique into an osteogenic alkaline phosphatase-positive compartment and an outer nonosteogenic compartment. Specific markers (nonspecific esterase [NSE], tartrate-resistant acid phosphatase [TRAP], and ED1 antibody, a marker of the monocyte-macrophage lineage) were used to follow osteoclast differentiation quantitatively as a function of time after activation of resorption, from day 0 to day 4 (peak of resorption in this model). Local cell proliferation was assessed in parallel. Between day 0 and day 3, the thickness of the osteogenic compartment decreased by 50% (p < 0.0002). In the osteogenic compartment, proliferating cell numbers fell by 80% at 12 day, NSE(+) cells (located farthest from the bone surface) increased 3. 9-fold on day 4 vs. day 0 (p < 0.005), ED1(+) cells decreased between day 0 and day 2 (p < 0.02) before returning to their initial value, and TRAP(+) cells increased 2.7-fold between day 1 and day 3 (p < 0.0005). Resorption was absent in the site studied on day 0, but on day 4 there were 20.5 osteoclast nuclei per millimeter of bone surface. The cell ratio changed from 30.3 NSE(+) and ED1(+) (some of which were also TRAP(+)) cells per millimeter on day 0 to 37.6 mononucleated cells plus 20.5 osteoclast nuclei on day 4. In the nonosteogenic compartment, an entry of ED1(+)/NSE(-) was observed on 12 day (+23 cells, p < 0.02 vs. day 0). This was followed by a return of ED1(+) cell numbers to the control level on day 1, and a transient increase in NSE(+) cells (+47% on day 2 vs. day 1, p < 0.02). TRAP(+) cells were never seen in this compartment. Proliferating cell numbers did not change throughout the study. Our results strongly suggest that the osteoclasts present on day 4 differentiated from the pool of TRAP(+), ED1(+), and NSE(+) cells present at the site on day 0. The osteogenic compartment was gradually replenished by cells migrating from the nonosteogenic compartment, which was supplemented by ED1(+) cells recruited from the circulation early after activation. Moreover, osteogenic cells appeared to be as crucial in vivo for the acquisition of the TRAP phenotype as previously shown in vitro.

Alkaline Phosphatase↗