SEARCH · PubMed Health

Results for “Acceleration”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources

PubMed2000

Telomere length shortening in chronic myelogenous leukemia is associated with reduced time to accelerated phase.

Telomere shortening is associated with disease evolution in chronic myelogenous leukemia (CML). We have examined the relationship between diagnostic telomere length and outcome in 59 patients with CML who entered into the MRC CMLIII Trial by Southern blot hybridization using the (TTAGGG)(4) probe. Age-adjusted telomere repeat array (TRA) reduction was found to significantly correlate with time from diagnosis to acceleration, such that patients with a larger TRA reduction entered the accelerated phase more rapidly (r = -0.50; P =.008). Cox-regression analysis for this group was suggestive of a relationship between a greater TRA-reduction and a shorter time to acceleration (P =.054). Age-adjusted TRA reduction did not significantly affect either the time to blast crisis or overall survival. Our results show that telomere shortening observed at the time of diagnosis in CML significantly influences the time to progress to the accelerated phase. The measurement of diagnostic TRA may prove to be clinically important in the selection of patients at high risk of disease transformation in CML.

Age Factors↗

PubMed1975

Acceleration of amyloidosis by syngeneic spleen cells from normal donors.

Intravenous administration of syngeneic spleen cells from normal donors was found to markedly shorten the induction time for casein-associated splenic amyloid diposition in the mouse. The effect of intravenous donor cells seemed purely one of acceleration; it did not provoke amyloid deposition either by itself or in combination with independently ineffective heterologous proteins. The accelerator effect did not depend on the viability of the cell suspension, and after physical disruption of the cells all the accelerator activity seemed localized to the sedimentable fraction of damaged cells, nuclei and coarse debris. It is suggested that the accelerator acts through affecting the function of perifollicular splenic macrophages.

Amyloid↗

PubMed2001

The role of arterial elastance in ventricular-arterial coupling in normal gravity and altered acceleration environments.

The role of physiological elastance (Ep) in maximizing external work (EW) transfer is not well understood and has not been investigated during microgravity and increased acceleration conditions. By better understanding this relationship, cardiovascular control mechanisms for meeting metabolic demands during normal gravity and altered acceleration stresses may be elucidated. Therefore, the objectives of this study were to determine the effect of Ep in maximizing EW of the left ventricle and to investigate this relationship during altered acceleration states. Ventricular and arterial parameters were estimated using established lumped parameter models from isolated beats of experimental data. These data were obtained during parabolic flight (0 and approximately 2 Gz) and centrifuge runs (approximately 1 to approximately 4 Gz) where acceleration was used to drive the cardiovascular system into a wide range of physiologic operating and coupling conditions. Parameter estimates at each Gz level were used in a series of computer simulations in which Ep was varied over a wide range to find the point of maximum EW for that coupling condition. Cardiac output and mean arterial pressure were maintained throughout the simulation process by adjusting heart rate. Results of the simulation showed that as arterial elastance decreased from its initially estimated (physiologic) value, external work increased slightly and as elastance increased, external work decreased. In particular, we found that the arterial elastance was set at a point near that which would produce maximal external work. In addition, it was found that altered Gz states may affect the Ep-EW relationship.

Animals↗

PubMed2001

Electromagnetic acceleration of electron transfer reactions.

The Moving Charge Interaction (MCI) model proposes that low frequency electromagnetic (EM) fields affect biochemical reactions through interaction with moving electrons. Thus, EM field activation of genes, and the synthesis of stress proteins, are initiated through EM field interaction with moving electrons in DNA. This idea is supported by studies showing that EM fields increase electron transfer rates in cytochrome oxidase. Also, in studies of the Na,K-ATPase reaction, estimates of the speed of the charges accelerated by EM fields suggest that they too are electrons. To demonstrate EM field effects on electron transfer in a simpler system, we have studied the classic oscillating Belousov--Zhabotinski (BZ) reaction. Under conditions where the BZ reaction oscillates at about 0.03 cycles/sec, a 60 Hz, 28 microT (280 mG) field accelerates the overall reaction. As observed in earlier studies, an increase in temperature accelerates the reaction and decreases the effect of EM fields on electron transfer. In all three reactions studied, EM fields accelerate electron transfer, and appear to compete with the intrinsic chemical forces driving the reactions. The MCI model provides a reasonable explanation of these observations.

Biochemical Phenomena↗

PubMed2001

Bromelain is an accelerator of phagocytosis, respiratory burst and Killing of Candida albicans by human granulocytes and monocytes.

OBJECTIVE: The aim of this study was to examine the influence of immuno modulating agents like bromelain and trypsin (e.g. Wobenzym on granulocyte and monocyte functions in healthy volunteers and patients with disorders of the humoral immuno system X-linked agammaglobulinaemia (XLA) and common variable immuno deficiency (CVID) and to find out whether the unspecific immunity could be improved by these enzymes. METHODS: In a whole-blood assay kinetics of phagocytosis, respiratory burst and killing (PBK) were measured in blood samples incubated with and without bromelain and trypsin (B/T) using Candida albicans as target organism. The time-reaction curves were analysed determining their gradient (T1) and their onset (T2) as well as the half effect time (HET). RESULTS: Phagocytes from patients with XLA showed a significantly accelerated basal phagocytosis (reduction of HET by 24% p < 0.001) compared to healthy controls. After incubation with B/T (10 microg/ml each) speed of phagocytosis was nearly doubled (phagocyte activity p < 0.0001, Candida uptake p < 0.003), T2 of respiratory burst was reduced by 65 % (p < 0.0001) and killing was accelerated by 27% (p < 0.046). However, the maximal activities of all kinetics were not altered. Incubation of phagocytes from healthy controls with B/T accelerated phagocytosis to a level comparable to that of untreated phagocytes from patients with XLA and also accelerated reactive oxygen species (ROS) production (reduction of HET by 28%, p < 0.012). In contrast to phagocytes from patients with XLA, phagocytes of patients with CVID showed a similar stimulation by B/T like healthy controls. Further experiments with the single substances showed that bromelain was the active compound. CONCLUSION: Our data suggest, that bromelain possesses immuno stimulatory properties. Phagocytes of XLA patients appear to be particularly susceptible to this stimulation.

Adjuvants, Immunologic↗

PubMed2000

Recombinant bovine basic fibroblast growth factor accelerates wound healing in patients with burns, donor sites and chronic dermal ulcers.

OBJECTIVE: To evaluate the effect of recombinant bovine basic fibroblast growth factor (rbFGF) on accelerating healing of burn wounds, donor sites and chronic dermal ulcers in multicenters. METHODS: One thousand and twenty-four patients with burns, donor sites and chronic dermal ulcers were recruited for this prospective and multicenter clinical trial and another 641 patients with the similar wounds were used as controls. All patients were divided into three groups: burn group, donor site group, and chronic dermal ulcer group. In the burn group, 654 patients with superficial second-degree burns(superficial II degree) or deep second-degree burns(deep II degree) were treated topically with either recombinant bovine basic fibroblast growth factor (rbFGF plus vehicle, rbFGF 150 AU/cm2/day, 330 patients) or placebo (vehicle without rbFGF, 324 patients). In the donor site group, 509 patients were treated with rbFGF and 317 patients with placebo in a similar way as described elsewhere. In the chronic dermal ulcer group, 185 patients were treated with rbFGF and the controls were themselves. Photography, histological evaluation and clinical examination were used to evaluate the results of wound healing. RESULTS: All of superficial second-degree burns, deep second-degree burns and the donor sites treated with recombinant bovine basic fibroblast growth factor had an accelerated rate of granulation tissue formation and epidermal regeneration as compared with that in the controls. Superficial second-degree burns and deep second-degree burns treated with recombinant bovine basic fibroblast growth factor healed in 9.89 +/- 2.45 and 17.04 +/- 4.56 days, respectively, whereas the average healing time in those receiving placebo was 12.35 +/- 2.74 and 21.21 +/- 4.88 days. The donor sites treated with rbFGF or placebo healed in 10.68 +/- 4.55 and 14.74 +/- 6.46 days, respectively. All chronic dermal ulcers except 12 patients treated with rbFGF healed within 6 weeks. Histological evaluation of punch-biopsy specimens from the burn wounds, donor sites and chronic dermal ulcers seven days after treatment supported the impression of accelerated wound healing after rbFGF treatment. CONCLUSIONS: rbFGF is effective in shortening the wound healing time and improving the wound healing quality. Accelerating wound healing is of clinical benefit in reducing the length of hospitalization, costs and emotional burden of the patient.

Adolescent↗

PubMed1975

Double ectopic accelerated ventricular and nonaccelerated ventricular or supraventricular rhythms.

Three patients with acute inferior wall myocardial infarction has accelerated idioventricular rhythms alternating and (or) coexisting with: (a) AV junctional (or low atrial) rhythm (Case 2); (b) paroxysmal ventricular tachycardia and another accelerated idioventricular rhythm (Case 3); and (c) AV junctional rhythm, paroxysmal ventricular tachycardia and accelerated idioventricular rhythm from another center (Case 4). The tracings from a fourth patient (Case 1) served to focus attention on one of the most pertinent features of accelerated idioventricular rhythms, namely the gradual decrease in rate to values below that of the preexisting basic rhythm. Cardioacceleration with atropine and cardiosuppression with lidocaine failed to abolish the arrhythmias or relieve the symptoms in cases 3 and 4. Atrial stimulation proved the most effective mode of therapy in these two patients.

Arrhythmias, Cardiac↗

PubMed2002

Physiological implications of mechanical effects of +Gz accelerations on brain structures.

BACKGROUND: In certain flight configurations, fighter pilots are exposed to high Gz acceleration (G) which may induce inflight loss of consciousness (G-LOC). When acceleration is of high amplitude, and the onset rate very rapid, G-LOC can occur extremely suddenly. HYPOTHESIS: Mechanisms other than brain hypoxia could be involved, enhancing its effects. In order to study the mechanical effects induced by such accelerations on cerebral structures, we estimated the stresses imposed on cerebral tissue when the brain is exposed to +Gz acceleration forces. METHODS: An "in vitro" experiment was performed to measure brain deformations during centrifugation. A finite element model of the brain was formulated. RESULTS: Computations indicate that traction and shear stresses are enhanced around the tentorial notch, and that compression stresses increase at the base of the cerebral hemispheres. CONCLUSION: The amplitude of these stresses is not sufficient to directly disturb proper nerve cell functioning. However, they could interfere with brain vessels as external surface forces, thus enhancing vessel collapse and brain ischemia.

Aerospace Medicine↗

PubMed2002

Accelerated recovery after cardiac operations.

BACKGROUND: The accelerated-recovery approach, involving early extubation, early mobility, decreased duration of intensive care unit stay, and decreased duration of hospitalization has recently become a controversial issue in cardiac surgery. METHODS: We investigated timing of extubation, length of intensive care unit stay, and duration of hospitalization in 225 consecutive cardiac surgery patients. Of the 225 patients, 139 were male and 86 were female; average age was 49.73 +/- 16.95 years. Coronary artery bypass grafting was performed in 127 patients; 65 patients underwent aortic and/or mitral or pulmonary valvular operations; 5 patients underwent valvular plus coronary artery operations; and in 28 patients surgical interventions for congenital anomalies were carried out. RESULTS: The accelerated-recovery approach could be applied in 169 of the 225 cases (75.11%). Accelerated-recovery patients were extubated after an average of 3.97 +/- 1.59 hours, and the average duration of stay in the intensive care unit was 20.93 +/- 2.44 hours for these patients. Patients were discharged if they met all of the following criteria: hemodynamic stability, cooperativeness, ability to initiate walking exercises within wards, lack of pathology in laboratory investigations, and psychological readiness for discharge. Mean duration of hospitalization for accelerated-recovery patients was 4.24 +/- 0.75 days. Two patients (1.18%) who were extubated within the first 6 hours required reintubation. Four patients (2.36%) who were sent to the wards returned to intensive care unit due to various reasons and 6 (3.55%) of the discharged patients were rehospitalized. CONCLUSIONS: Approaches for decreasing duration of intubation, intensive care unit stay and hospitalization may be applied in elective and uncomplicated cardiac surgical interventions with short duration of aortic cross-clamping and cardiopulmonary bypass, without risking patients. Frequencies of reintubation, return to intensive care unit, and rehospitalization are quite low with this approach.

Adult↗

PubMed2002

Comparison of conventional and accelerated hepatitis B immunisation schedules for homeless drug users.

This historical control study examines the uptake of two hepatitis B immunisation schedules at an inner city primary care centre for homeless people in Northern England. Originally homeless patients disclosing current or past illicit drug use were offered hepatitis B immunisation. In 1999 a conventional hepatitis B vaccine schedule was offered (immunisations at 0, 1, and 6 months) whereas in 2000 an accelerated schedule was introduced (immunisations at 0, 7 and 21 days). There was an increase in the uptake of hepatitis B vaccination by homeless drug users once the accelerated schedule was introduced. Furthermore, the completion rates for the accelerated vaccination regimen were almost seven times higher than for the conventional one. This indicates that the accelerated hepatitis B schedule should be the regime of choice for patients with a current or past history of drug use.

Chi-Square Distribution↗

PubMed1999

Androgen induced acceleration of functional recovery after rat sciatic nerve injury.

PURPOSE: Testosterone (T) treatment accelerates recovery from facial paralysis after facial nerve crush in hamsters. In this study, we extended those studies to another injury model and asked the following question: Will T treatment accelerate recovery from lower limb paralysis following sciatic nerve crush in the rat? METHODS: Castrated adult male rats received a right side sciatic nerve crush at the level of the sciatic notch, with the left side serving as control. Half the animals received a subcutaneous implant of a propionated form of T (TP), the others were sham-implanted. Weekly testing using the Sciatic Functional Index (SFI), a quantitative measure of locomotion, was done for 7 weeks postoperative (wpo). RESULTS: Between 3 and 5 weeks post-op, the average SFI score of the TP-treated group was higher than controls. This difference was significant at 4 wpo, indicating an accelerated degree of functional recovery. At these timepoints, the differences were attributable to the footprint or paw length and associated with calf muscle reinnervation rather than the toespreading component associated with intrinsic foot muscle rein-nervation. Beyond 5 wpo, there were no differences in the SFI scores. CONCLUSION: The results indicate that, as with facial nerve regeneration in the hamster, testosterone accelerates functional recovery from hind limb paralysis following sciatic nerve injury in the rat. While the responses of spinal motoneurons to injury can differ from those of cranial motoneurons, in this case it appears that they share a similar response to the trophic actions of androgen. This is important in the context of designing therapeutic strategies for dealing with direct trauma to motoneurons resulting from both peripheral and central nervous system trauma, such as spinal cord injury.

Journal Article↗

PubMed2002

Accelerated atherosclerosis.

The process of accelerated atherosclerosis appears to share common pathophysiologic mechanisms, namely, endothelial injury with early platelet involvement and subsequent progressive smooth muscle cell proliferation and thrombosis leading to vascular occlusion. Understanding the mechanisms of this process has made it possible to include strategies to limit vascular injury and reduce subsequent thrombotic and proliferating cellular responses. In contrast to spontaneous atherosclerosis, a more significant denuding endothelial injury appears to be the critical initiating event, followed by intense platelet involvement and thrombus formation, leading to an initial predominant process of smooth muscle cell proliferation in accelerated atherosclerosis. Risk factors like cigarette smoking and hypertension play an important role in this process. This accelerated proliferative process appears to be the cause of premature coronary occlusion in patients undergoing heart and kidney transplantation, coronary vein graft bypass and percutaneous transluminal coronary angioplasty and diabetes. This accounts for significant morbidity and mortality in these patients. Prophylactic anticalcinotic vasoprotection by suitable calcium antagonists may offer a more appropriate way of anti-arteriosclerotic arterial protection than the other procedures hitherto used. Calcium channel blockers have positive effects on a number of processes that may be associated with restenosis, including reduction of platelet aggregation, minimisation of vasospasm and inhibition of mitogens. In this article the role of nifedipine in accelerated atherosclerosis has been reviewed.

Arteriosclerosis↗

PubMed1992

Accelerated nodulosis during low dose methotrexate therapy for rheumatoid arthritis. An analysis of ten cases.

OBJECTIVE: To obtain information on the occurrence of accelerated nodulosis during methotrexate (MTX) for rheumatoid arthritis (RA), localization, size and presence in heart and lungs of these nodules, predisposing factors, relationship with other extraarticular manifestations (EAM) and their histological features. METHODS: Ten patients with accelerated nodulosis were studied. Four participated in a double blind study of MTX and azathioprine. Patient characteristics, localization, size and histopathology of new nodules were determined. Echocardiography and chest roentgenograms were performed. RESULTS: Accelerated nodulosis occurred exclusively during treatment with MTX in our double blind study. The estimated incidence was 8%. One patient reported was rheumatoid factor negative. Newly developed nodules were small, and located in the fingers in all patients and in additional sites in 7. Pretreatment nodules were not found in the fingers. In one patient nodules on the mitral valve were found, but this was not likely to be associated with the use of MTX. No new pulmonary nodules were found. Other EAM developed concurrently in 4 patients. Histopathology revealed typical rheumatoid nodules. In 3 patients nodulosis regressed after MTX was stopped. In 2 of them they recurred after a rechallenge. CONCLUSIONS: Accelerated nodulosis during MTX for RA is not rare, and occurs despite good clinical response of polyarthritis. Rheumatoid factor positivity is not a prerequisite. New nodules are small and preferentially located in the fingers. Recurrence after rechallenge with MTX suggests causality.

Aged↗

PubMed2003

Acute soft tissue neck injury from unexpected acceleration.

Recent evidence has identified a risk of neck injury resulting from exposure to high sustained G force during operation of fast jet military aircraft. This review considers the risk of acute soft tissue neck injury when exposure to acceleration is unexpected by the individual. In a military jet, this might occur to a back seat occupant such as an instructor or weapons operator/navigator, but unexpected forces may also be encountered by roller coaster riders and human centrifuge users under certain conditions. The mechanisms of injury in this situation are examined, the effect of acceleration axes (Gx, Gy, and Gz) are considered, and relevant experimental data are evaluated. These data are used to determine what influence the unexpected nature of the acceleration exposure has on the risk of neck injury. Injury below previously established 'tolerance' limits is possible, with some individuals being at risk from unexpected acceleration exposure above around +2 to .

Aerospace Medicine↗

PubMed1992

Metabolic acidosis accelerates whole body protein degradation and leucine oxidation by a glucocorticoid-dependent mechanism.

Previous work documented an acceleration of proteolysis and branched-chain amino acid oxidation when muscles from rats with chronic metabolic acidosis were incubated in vitro. The present study examines the impact of chronic metabolic acidosis on whole body amino acid turnover and oxidation in chronically catheterized, awake, male Sprague-Dawley rats using stochastic modeling and a primed continuous infusion of L[1-14C] leucine. Whole body protein turnover was accelerated by acidosis as reflected in a 70% increase in proteolysis and a 55% increase in protein synthesis. Amino acid oxidation was increased by 145% in rats with acidosis relative to control rats receiving diets identical in protein and calories based on a reciprocal pool model and plasma alpha-ketoisocaproate specific radioactivity. These changes were accompanied by a 104% increase in liver branched-chain ketoacid dehydrogenase (BCKAD) activity in rats with acidosis, similar to previously documented increases in skeletal muscle BCKAD activity caused by acidosis. In contrast, kidney BCKAD activity was decreased by 38%, illustrating the tissue specificity of the changes that were present. We conclude that chronic metabolic acidosis accelerates whole body protein turnover and reduces the efficiency of protein utilization by accelerating amino acid oxidation. These changes may require an intact glucocorticoid axis.

Acidosis↗

PubMedDate not supplied

Immunohistochemical studies of age-associated amyloid deposition in the joint of senescence-accelerated mouse (SAM).

The senescence-accelerated mouse (SAM) is a murine model of accelerated senescence and consists of the senescence-accelerated prone mouse (SAM-P) and senescence-accelerated resistant mouse (SAM-R), the latter of which shows normal aging characteristics. SAM shows a high incidence of age-associated microscopic amyloid deposition in synovial joints and intervertebral discs and the lesion is histologically quite similar to that of humans. The amyloid fibril protein of these mice is well characterized as a murine systemic senile amyloid (ASSAM). Twenty SAM-P and three SAM-R mice were used for this immunohistological study. Synovial joints and intervertebral discs were stained by immunoperoxidase method (PAP) using anti-ASSAM and anti-mouse AA antibodies and compared with birefringence in a Congo-red-stained section. Positive staining was observed in annulus fibrosus of the intervertebral discs, blood vessels, synovia, and on the surfaces of the meniscus and articular cartilage, exactly at the same site where green birefringence in Congo-red staining was observed. Both ASSAM and AA existed in the articular structures of SAM and the incidence of AA was significantly correlated with systemic signs of inflammation at autopsy. Among blood vessels, synovium and articular cartilage, there was no one tissue where amyloid deposited earlier than others. It was postulated that amyloid is transported via synovial fluid as its fibrillar form or as a precursor and that it deposits on the surface of articular cartilage.

Aging↗

PubMed2003

A partnership model to address the nursing shortage. The KSU accelerated BSN Program.

Metropolitan Atlanta and northwest Georgia, like other regions of the United States, face a critical shortage of nurses. To address this shortage, the Kennesaw State University (KSU) School of Nursing (SON) has developed and implemented a partnership model to offer second-degree students an accelerated BSN Program. The KSU model builds on a competitive statewide initiative that targets funds to educational and corporate collaborations as well as a growing number of nursing school non-nurse applicants who hold other baccalaureate degrees. To offer the accelerated BSN Program, the KSU nursing faculty developed an accelerated curriculum model that allows completion in 16 months. Further, a six member, collaborative partnership has been constructed to allow this curriculum to be offered to 40 second-degree students both on the KSU campus and as an outreach program in rural northwest Georgia. This article describes the accelerated BSN curriculum model as well as the partnerships constructed to implement and fund the program.

Community Networks↗

PubMed2004

[Accelerated angiogenesis in artificial dermis with allogenic cultured dermal fibroblasts transplantation].

OBJECTIVE: To evaluate the effects of cryopreserved cultured allogenic dermal fibroblasts on angiogenesis and fibroplasia while artificial dermis grafting by spraying the cells on the graft bed. METHODS: Full thickness skin defect was made on the back of Wistar rat, fibroblasts mixed into fibrin glue (fibroblast group) and same amount fibrin glue (control group) were sprayed separately between the wound bed and artificial dermis in cell density of 1.0 x 10(5) cells/cm2 before the artificial dermis was grafted. On day 5 after grafting, the graft and surrounding tissue were examined histologically for angiogenesis and fibroplasia in the dermis and wound bed with hematoxylin eosin stain, VEGF antibody stain, Masson's trichrome stain and India ink stain. Evans blue perfusion method was also used for detecting the angiogenesis quantitatively. RESULTS: In the fibroblast group, the angiogenesis of graft bed was significantly accelerated on day 5 after grafting; the numbers of the newly formed capillaries were 9.64 +/- 2.36/HP in the fibroblast group and 3.88 +/- 1.62/HP in the control group (P < 0.05). And on day 10 after grafting the angiogenesis was accelerated not only in graft bed but also in the artificial dermis when compared with control group, the newly formed capillaries network was clearly observed in the artificial dermis. Otherwise, the synthesis of collagen was increased in the dermis on day 10 after grafting in the fibroblast group when compared with control group. The immunoreactivity of VEGF antibody in the fibroblast group also showed a stronger expression than that in control group on day 5 after grafting, the numbers of positive cells were 46.04 +/- 8.90/HP in the fibroblast group and 30.08 +/- 7.76/HP in the control group(P < 0.05). CONCLUSION: Transplantation of cryopreserved dermal fibroblasts while artificial dermis grafting can accelerate the angiogenesis and fibroplasia in the artificial dermis and graft bed, thereby accelerate the formation of dermal-like tissue in the artificial dermis.

Animals↗