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PubMed2003

In vitro analysis of stone fragmentation ability of the FREDDY laser.

BACKGROUND AND PURPOSE: The Frequency-Doubled Double-Pulse Nd:Yag) (FREDDY) laser (World of Medicine, Berlin Germany) is a short-pulsed, double-frequency solid-state laser with wavelengths of 532 and 1064 nm. This low-power, low-cost laser was developed for intracorporeal lithotripsy. We designed an experimental set-up to test its fragmentation efficiency at different energy and frequency settings. MATERIALS AND METHODS: Forty previously weighed plaster-of-Paris stone phantoms were divided into four groups in order to test fragmentation at 5 and 10 Hz for 2 and 4 minutes. A hands-off underwater laboratory set-up including a holder to keep the stone phantom in contact with the quartz laser fiber was utilized. The 280-microm laser fiber was cleaved and stripped between runs to ensure optimal energy delivery. After fragmentation was completed, all of the stone fragments remaining within the holder were allowed to desiccate for 48 hours and reweighed. Fragmentation was measured as the percentage weight loss. RESULTS: Stone phantoms fragmented at 5 Hz for 2 minutes sustained a mean 24% loss of weight, whereas the 4-minute treatment at 5 Hz reduced stone weight by 54%. Treatment at 10 Hz for 2 minutes demonstrated results similar to those of stones treated for 4 minutes at 5 Hz, reducing stone weight by 51%. Fragmentation at 10 Hz for 4 minutes revealed a 64% loss of mass, less than expected for these power settings. Fiber deterioration observed at the higher energy settings may be the cause of the reduced stone-fragmentation efficiency. CONCLUSIONS: Fragmentation with the FREDDY laser in the 5 Hz, 4 minutes and 10 Hz, 2 minutes protocols is comparable, suggesting that stone fragmentation correlates well with the total energy delivered to the stone. The slight drop in fragmentation efficiency at 10 Hz, 4 minutes is most likely explained by fiber damage occurring consistently at these higher energy settings. The safety profile and low investment and running costs of this laser are advantages that suggest the laser warrants further clinical trials.

In Vitro Techniques↗

PubMed2005

Energy balance and breast cancer risk.

We evaluated the hypothesis that a pattern of behavioral exposures indicating positive energy balance [i.e., less exercise/sport activity, high body mass index (BMI), or high energy intake] would be associated with an increased breast cancer risk in the Shanghai Breast Cancer Study, a population-based study of 1,459 incident breast cancer cases and 1,556 age frequency-matched controls. Participants completed in-person interviews that collected information on breast cancer risk factors, usual dietary intake and physical activity in adulthood. Anthropometric indices were measured. Odds ratios and 95% confidence intervals were estimated by logistic regression to describe the individual and joint effects of the exposures on breast cancer risk. Lack of exercise/sport activity, low occupational activity, and high BMI were all individually associated with increased risk of breast cancer [odds ratios (OR) ranged from 1.49 to 1.86]. In general, women with lower exercise/sport activity level and higher BMI, or those with higher energy intake, were at an increased risk compared with women who reported more exercise/sport activities, had lower BMIs, or reported less energy intake. There was a significant multiplicative interaction (P = 0.02) between adult exercise/sport activity and BMI, with inactive women in the upper BMI quartile being at increased risk (OR, 2.16; 95% confidence interval, 1.25-3.74) compared with their active and lean counterparts. This association was stronger in postmenopausal than in premenopausal women, and non-exercising postmenopausal women with higher BMIs were at substantially increased risk (OR, 4.74; 95% confidence interval, 2.05-12.20). Our study suggests that promotion of behavior patterns that optimize energy balance (weight control and increasing physical activity) may be a viable option for breast cancer prevention.

Adult↗

PubMed1987

Novel mu-selective Met-enkephalinamide analogs with antagonist activity. Synthesis, receptor binding, analgesic properties and conformational studies.

Four novel mu-selective peptide antagonists have been synthesized and examined for receptor binding, analgesic agonist and antagonist activity and energy conformational properties. These peptides were designed by analogy to results of molecular modeling of 3-phenyl piperidines which led to incorporating four modified tyrosine residues, m-Tyr, beta-methyl-m-Tyr, N-phenethyl-m-Tyr and alpha, beta-dimethyl-m-Tyr into D-Ala2-Met5-enkephalinamide. Peptides were synthesized by stepwise solution synthesis using an active ester coupling procedure. Receptor binding assays were performed on rat brain homogenates and data were analyzed by a modified version of the program LIGAND. Analgesic agonist and antagonist activity was evaluated by the mouse tail-flick test. Energy-optimized conformations were obtained using a program called Molecule-AIMS. The results demonstrate that relative ratios of in vivo agonist and antagonist potencies in D-Ala2-Met5-enkephalinamides can be modulated by chemical modification of the tyrosine residue. A shift in the phenolic-OH position from para to meta significantly enhances relative antagonist versus agonist activity; addition of a beta-CH3 group to the m-Tyr enhances mu-selectivity and leads to nearly equal agonist/antagonist activity. Energy conformational studies indicate that all analogs with high mu-receptor affinity examined have a common energy accessible B'II 2-3 turn conformation similar to that previously identified for high mu-affinity binding in peptides, lending further support to this candidate conformer. This conformer also has tyrosine side-chain angles which allowed total overlap with the amine and phenolic groups of a known structure of 3-(m-OH phenyl)-piperidine. This structural similarity together with the observation of mixed agonist antagonist activity in both types of opioids confirms the rationale upon which design of these peptides was based.

Animals↗

PubMed1992

DNA flexibility as a function of allomorphic conformation and of base sequence.

Systematic theoretical modeling of symmetric DNA oligomers, carried out earlier for the B conformation, is now extended to A-DNA. In contrast to the previous results, it is found that A-DNA shows no multiplicity of low-energy substate conformations. The possibilities of the Jumna algorithm are subsequently applied to studying deformations of the oligomers. Controlled winding and stretching deformations are used to study how the two allomorphs and different base sequences absorb such external stress. The results help explain the internal mechanics of the DNA double helix and the extent to which fine structure influences this behavior. The results point to some differences between the A and B double helices, but also to many similarities. Sequence effects on flexibility are relatively limited compared to their impact on optimal energy conformations. It is also shown that the conformational substates detected for B-DNA oligomers are preserved under deformation, but have little influence on its energetics.

Base Sequence↗

PubMed1991

Histopathology of continuous wave neodymium: yttrium aluminum garnet and diode laser contact transscleral lesions in rabbit ciliary body. A comparative study.

Neodymium: yttrium aluminum garnet (Nd:YAG) laser transscleral cyclophotocoagulation has been shown to be an effective method of lowering intraocular pressure (IOP). Transmission and absorption features of diode laser radiation (810 nm) make these new laser sources suitable for production of transscleral thermal lesions. The transscleral effects on rabbit ciliary body of Nd:YAG and diode laser wavelengths were compared using a CW Nd:YAG laser and a CW Aluminum Gallium Arsenide diode laser. Both lasers were delivered by silica optic fibers, 600 microns in diameter. Eight rabbits were treated by applying the optic fiber 0.5 mm from limbus while increasing energy values from 0.2-2 J. The lesions produced at equal energy values underwent gross and histologic and ultrastructural comparison. Gross examination revealed threshold lesions at 1 J energy for the Nd:YAG laser and 0.8 J for the diode laser. The diode laser produced transscleral thermal lesions of the rabbit ciliary body comparable to those achieved by the Nd:YAG laser. The histologic and ultrastructural study showed that diode laser radiation produced more remarkable damage to the ciliary pigmented structures, causing deep coagulation necrosis of the pigmented epithelium, wide disorganization of the collagen in the stroma, and intravascular coagulation phenomena in the ciliary vessels. Before the introduction of these new laser sources in clinical transscleral procedures, further investigation is needed to determine optimal energy levels.

Animals↗

PubMed2002

Short day lengths attenuate the symptoms of infection in Siberian hamsters.

Symptoms of infection, such as fever, anorexia and lethargy, are ubiquitous among vertebrates. Rather than nonspecific manifestations of illness, these responses are organized, adaptive strategies that are often critical to host survival. During times of energetic shortage such as winter, however, it may be detrimental for individuals to prolong energetically demanding symptoms such as fever. Individuals may adjust their immune responses prior to winter by using day length to anticipate energetically-demanding conditions. If the expression of sickness behaviours is constrained by energy availability, then cytokine production, fever, and anorexia should be attenuated in infected Siberian hamsters housed under simulated winter photoperiods. We housed hamsters in either long (14 L : 10 D) or short (10 L : 14 D) day lengths and assessed cytokines, anorexia and fever following injections of lipopolysaccharide (LPS). Short days attenuated the response to lipopolysaccharide, by decreasing the production of interleukin (IL)-6 and IL-1beta, and diminishing the duration of fever and anorexia. Short-day exposure in hamsters also decreased the ingestion of dietary iron, a nutrient vital to bacterial replication. Taken together, short day lengths attenuated the symptoms of infection, presumably to optimize energy expenditure and survival outcome.

Adaptation, Physiological↗

PubMed1987

[Sutureless method of micro-vascular anastomosis using low-energy Nd-YAG laser].

Sutureless end-to-end anastomosis of rat common carotid artery was carried out, low energy Nd-YAG laser being used thereby. An intraluminal-intervascular splint, made of water-soluble poval, was used for precise adaptation of the intimas. Neither stay suture nor glue was required. The patency rate of the anastomosed vessels, 24 hours after operation, was as high as 91%. The vessels were confirmed to be likewise patent on the 7th and 30th postoperative day. Complications such as pseudoaneurysm formation or stenotic change, were negligible. The fusion of the anastomosis with Nd-YAG laser was histologically proved to be satisfactory and the result of tensile strength test was excellent. Temperature at the anastomotic site during laser irradiation was measured, optimal energy for anastomosis determined and possible mechanism of vascular fusion by laser beam postulated. The major advantages of the laser technique combined with poval splint, such as rapidity, consistency and no residual foreign body (thread or adhesive), are discussed.

Anastomosis, Surgical↗

PubMed2003

Fluorescence resonance energy transfer between donor-acceptor pair on two oligonucleotides hybridized adjacently to DNA template.

We use fluorescein as the energy donor and rhodamine as the acceptor to measure the efficiency of fluorescence resonance energy transfer (FRET) in a set of hybridized DNA constructs. The two fluorophores are covalently attached via linkers to two separate oligonucleotides with fluorescein at the 3' end of one oligonucleotide and rhodamine at the 5' end or in the middle of another nucleotide. For the FRET analysis both fluorophore-labeled oligonucleotides are hybridized to adjacent sections of the same DNA template to form a three-component duplex with a one base gap between the two labeled oligonucleotides. A similar configuration is implemented for a quantitative real-time polymerase chain reaction (PCR) with LightCycler technology, where a 1-5 base separation between donor and acceptor is recommended to optimize energy transfer efficiencies. Our constructs cover donor-acceptor separations from 2 to 17 base pairs (approximately 10-70 A). The results show that, when the two fluorophores are located at close distances (less than 8 base separation), FRET efficiencies are above 80%, although there may be ground-state interactions between fluorophores when the separation is under about 6 bases. Modeling calculations are used to predict the structure of these three-component constructs. The duplex mostly retains a normal double helical structure, although slight bending may occur near the unpaired base in the DNA template. Stable and reproducible energy transfer is also observed over the distance range investigated here in real-time thermal cycling. The study identifies important parameters that determine FRET response in applications such as real-time PCR.

Base Sequence↗

PubMed2001

Metabolic energy metabolism in diabetes: therapeutic implications.

Diabetic alterations of myocardial metabolism result mainly from malfunctions of acetyl-coenzyme A carboxylase, carnitine-palmitoyl-transferase-I and pyruvate-dehydrogenase inducing an overshoot of fatty acid oxidation that inhibits glucose oxidation. Gene expression of pyruvate-dehydrogenase and glucose transporters and depression of the third step of the mitochondrial respiratory chain also contribute to the diabetic alterations of myocardial metabolism. Ischaemic cardiovascular alterations are common and treatment is rarely successful in cases of diabetes since fatty acid oxidation is the costliest metabolic pathway for oxygen. Thus, in diabetes, aerobic glycolysis gradually shifts to anaerobic glycolysis under ischaemia, with accumulation of lactate and acid metabolites that in turn induce myocardial deterioration, Animal experiments have demonstrated that elective depression of activity of carnitine-palmitoyl-transferase-I enzyme-activity promotes glucose oxidation and early rapid recovery of myocardial contractility, especially under diabetic conditions. To reduce diabetic alterations of myocardial metabolism, anti-diabetic treatment must be switched to insulin during the acute ischaemic and post-ischaemic period of coronary diseases. Trimetazidine optimizes energy metabolism by selectively inhibiting action of the 3-ketoacyl-coenzyme A thiolase enzyme involved in beta-oxidation and inhibiting the overshoot of fatty oxidation. Trimetazidine, as the first 3-ketoacyl-coenzyme A thiolase inhibitor, therefore provides permanent myocardial cytoprotection in stable angina pectoris. However, in our experience, this beneficial anti-anginal effect is only observed in well-controlled situations.

Angina Pectoris↗

PubMed2005

Study of pi halogen bonds in complexes C2H(4-n)Fn-ClF (n = 0-2).

The pi-halogen bond may be considered, in a broad sense, essentially a pi-hydrogen bond. Using the counterpoise-corrected potential energy surface method (interaction energy optimization), the stationary structures of the C2H(4-n)Fn-ClF (n = 0-2) complexes with all real frequencies have been obtained at the MP2/aug-cc-pVDZ level. For C2H(4-n)Fn-ClF (n = 0-2), the pi-halogen bond has a long distance and is elongated by the F substituent effect. The pi-halogen bond length order is 2.661 A for C2H4-ClF < 2.745 A for C2H3F-ClF < 2.766 A for g-C2H2F2-ClF < 2.8076 A for trans-C2H2F2-ClF < 2.8079 A for cis-C2H2F2-ClF. For three complexes C2H3F-ClF, g-C2H2F2-ClF, and cis-C2H2F2-ClF, the pi-halogen bonds are further shifted and sloped by the F substituent effect. The F substituent effect reduces also the interaction energy of the pi-halogen bond. The interaction energies are respectively -3.7 for C2H4-ClF, -2.8 for C2H3F-ClF, -2.3 for g-C2H2F2-ClF, -1.9 for cis-C2H2F2-ClF, and -1.8 kcal/mol for trans-C2H2F2-ClF, at the CCSD(T)/aug-cc-pVDZ level. The electron correlation contribution of the interaction energy is large for C2H(4-n)Fn-ClF (n = 0-2), which shows that the stabilities of the pi-halogen bond systems results primarily from the dispersion interaction. In the double F substituent systems, the interaction energy of the pi-halogen bond structure with a longer interaction distance is larger than that of the corresponding pi-hydrogen bond structure with a shorter interaction distance. This may be because there are the large electron correlation contributions of the interaction energy, and a secondary interaction between lone pairs of Cl atom and some atoms (H, C) with positive charges in the pi-halogen bond structure.

Chlorides↗

PubMed1975

Studies on the control of energy metabolism in mammalian cardiac muscle cells in culture.

Myocardial cells in a monolayer culture are a myogenic model system wihch shows functional differentiation and in which the intracellular metabolism and energy utilization do not differ markedly from those of the fresh tissue. In the myocardial cells, as in numerous other muscle tissues, the concentration of high energy phosphate compounds, primarily phosphorylcreatine, correlates well with the functional integrity of the cells. The decline of adenosine triphosphate (ATP) below a critical level leads to the cessation of rhythmic contractions of the cells in culture, and, conversely, an increased steady state level of ATP correlates with an increased rate of excitability. When creatine, in the concentration range known to be present in the cardiac tissue, is added to the growth medium of the cultured myocardial cells, the intracellular concentration of phosphorylcreatine increases up to 100%. Since the only metabolic path known for phosphorylcreatine synthesis is via creatine phosphokinase, the rate of transphosphorylation and ATP synthesis must have been increased. This stimulation of energy production is due to the regeneration of mitochondrial ADP brought about by the phosphosphorylation of creatine to phosphorylcreatine and possibly, also, to an enhanced rate of glycolysis. No net transfer of approximately P from ATP to creatine was observed under any of the experimental conditions. The high steady state level of phosphorylcreatine was not maintained upon the addition of either oligomycin or 2-deoxyglucose, and the addition of both metabolic inhibitors simultaneously resulted in a depletion of phosphorylcreatine and ATP and in cessation of rhythmic contractions. The excitability was also inhibited upon the addition of 1-fluoro-2,4-dinitrobenzene, a creatine phosphokinase inhibitor, and the accompanying depletion of approximately P was primarily reflected in a decrease of ATP concentration. These findings support the following conclusions: (1) phosphorylcreatine serves as a source of approximately P for the resynthesis of ATP at the site of utilization (i.e., myofibrils, membrane) and thus maintains the optimal energy charge; (2) production site; (3) the regeneration of phosphorylcreatine is coupled to oxidative phosphorylation and possibly to glycolysis. Creatine-phosphorylcreatine system operates as a undirectional shuttle for approximately P and as a control system regulating energy production according to demand. Reports of studies on intact mitochondria and on isoenzymes of creatine phosphokinase give further support to the above conditions.

Adenosine Triphosphate↗

PubMed1996

Energy substrate requirements for in vitro development of early cleavage-stage bovine embryos.

Energy substrate preferences of bovine cleavage-stage embryos produced by in vitro maturation and in vitro fertilization were examined in a chemically-defined (protein-free) culture medium modified hamster embryo culture medium-3, (mHECM3). Few inseminated ova cleaved without energy substrates. Glucose and/or glutamine could not support embryo development, but lactate alone was effective (37% 5-8-cells), equivalent to complex medium TCM-199 (44%). Addition of 11 selected amino acids to lactate increased embryo cleavages, although this treatment was not significantly different from pyruvate alone. Addition of glucose to lactate or to pyruvate depressed development. Lactate + amino acids was significantly better than TCM-199 (54% and 26% > or = 8-cells, respectively). Blastocyst development was evaluated after transferring > or = 8-cell embryos into a complex medium (TCM-199) containing serum. Cleavage-stage embryos produced with pyruvate alone or with lactate + amino acids yielded the highest proportions of blastocysts (36% and 41%, respectively, of inseminated ova). Between 33-63% of blastocysts derived from embryos that were initially developed in mHECM-3 supplemented with various substrates escaped from their zonae (hatched) depending on the treatment, but none of the embryos from the pyruvate + glucose combination hatched. This study shows that optimal energy substrates for bovine cleavage-stage embryo development can be determined using a chemically-defined culture medium, that a simple medium with selected substrates can support early development as well as or better than a complex medium, that a two-step culture system can be used to evaluate blastocyst development from these cleavage-stage embryos, and that timing and hatching of embryos may provide additional information about discriminating between the suitabilities of different substrates for early embryo development.

Amino Acids↗

PubMed2006

Randomized trial comparing holmium laser enucleation of prostate with plasmakinetic enucleation of prostate for treatment of benign prostatic hyperplasia.

OBJECTIVES: To compare the alternative energy sources of the holmium:yttrium-aluminum-garnet laser and bipolar plasmakinetic energy for endoscopic enucleation. METHODS: A prospective, randomized controlled trial was undertaken, with 20 patients assigned to each group. The preoperative and postoperative measures included transrectal ultrasound-assessed prostate volume, postvoid residual urine volume, and urodynamic evaluation findings. The intraoperative measures included procedure length, energy use, and specimen weight. All adverse events were recorded at each postoperative visit in a 1, 3, 6, and 12-month protocol. RESULTS: No differences were found in the preoperative characteristics between the two groups. The significant differences favoring holmium laser enucleation of the prostate compared with plasmakinetic enucleation of the prostate were seen in the operative time (43.6 versus 60.5 minutes), recovery room time (47.1 versus 65.6 minutes), and bladder irrigation requirement (5% versus 35%). The outcomes after holmium laser enucleation of the prostate and plasmakinetic enucleation of the prostate were in all other respects similar by the postoperative outcome measures assessed. CONCLUSIONS: Plasmakinetic enucleation of the prostate is a safe and technically feasible procedure for the enucleation of prostatic adenomata. Plasmakinetic enucleation of the prostate is limited by the longer operative and recovery room times, as well as a more pronounced postoperative irrigation requirement because of reduced visibility and a greater propensity for bleeding. The transfusion rates and catheterization and hospitalization times were similar. The optimal energy source for enucleation should still be considered the holmium laser, but bipolar energy can be considered by users already experienced with holmium laser enucleation of the prostate.

Aged↗

PubMed1996

Promotion of bone repair in the cortical bone of the tibia in rats by low energy laser (He-Ne) irradiation.

The effect of low energy laser (He-Ne) irradiation on bone repair in the cortical part of the tibia of the rat was investigated using biochemical and radioactive labeling methods. A fixed round hole was created in the lateral aspect of the tibia and the newly formed tissue was collected from the gap in the cortical bone. Alkaline phosphatase (ALP) and calcium progressively accumulated at the site of injury, peaking at 9 and 13 days postinjury, respectively. Direct irradiation of the hole injury with He-Ne laser on days 5 and 6 postinjury altered osteoblastic activity at the injured site as reflected by alkaline phosphatase activity. The laser irradiation also caused a significant increase ( approximately 2-fold) in calcium accumulation at the site of injury for 9-18 days postinjury. The rate of calcium deposition, measured by radioactive calcium, was significantly higher (approximately 2-fold) in the laser-irradiated rats as compared with controls. It is concluded that the process of bone repair in a hole created in the rat tibia is markedly enhanced by direct He-Ne laser irradiation of the injured site at the optimal energy level and time postinjury.

Animals↗

PubMed2004

Characteristic of structures and pi-hydrogen bond of dimers C2H4-nFn-HF (n=0,1,2).

By the counterpoise-correlated potential energy surface method (interaction energy optimization), five structures of the C(2)H(4-n)F(n)-HF (n = 0,1,2) dimers with all real frequencies have been obtained at MP2/aug-cc-pVDZ level. The influence of F substituent effect on the structure and pi-hydrogen bond of dimer has been discussed. For C(2)H(4-n)F(n)-HF (n = 1,2), the pi-hydrogen bonds are elongated comparing with that for C(2)H(4)-HF. For C(2)H(3)F-HF, g-C(2)H(2)F(2)-HF, cis-C(2)H(2)F(2)-HF, the pi-hydrogen bonds are further deformed. These changes (elongate, shift, and deformation) of pi-hydrogen bond mainly come from deformation of pi-electron cloud of C=C bond. The pi-electron cloud is pushed towards the one C atom, the pi H-bond shift also to the C direction. Since the two lobes of pi-electron cloud have deviated slightly from the molecular vertical plane passing through C=C bond, the pi-hydrogen bond is sloped. Intermolecular interaction energies of the dimers are calculated to be -3.9 for C(2)H(4)-HF, -2.8 for C(2)H(3)F-HF, -2.1 for g-C(2)H(2)F(2)-HF, -1.6 for cis-C(2)H(2)F(2)-HF, -1.3 kcal/mol for trans-C(2)H(2)F(2)-HF, at CCSD(T)/aug-cc-pVDZ level.

Journal Article↗

PubMed1999

Erbium:YAG laser cataract removal: role of fiber-optic delivery system.

PURPOSE: To review the properties of energy delivery systems and to evaluate the efficiency of zirconium-fluoride-based and sapphire fibers delivering erbium:YAG (Er:YAG) laser energy in a clinical laser cataract surgery system. SETTING: Department of Ophthalmology, Medical College of Virginia Campus of Virginia Commonwealth University, and Veterans Affairs Medical Center, Richmond, Virginia, USA. METHODS: Thirty-two patients had Er:YAG laser cataract extraction. Preoperative visual acuity ranged between finger counting and 20/40 secondary to cataract. The endothelial cell count was measured preoperatively and 6 weeks after surgery. A zirconium-fluoride-based fiber was used in 23 patients and a sapphire fiber in 9 patients. RESULTS: Of the patients examined after 3 months (n = 31), 90.3% (n = 28) had a visual acuity of 20/30 or better and 9.7% (n = 3), of 20/40 or 20/50. Mean endothelial cell loss at 6 weeks was 7.6% +/- 12.8 (SD). Posterior capsule rupture with vitreous loss occurred in 3 cases; 1 was attributed to laser damage to the capsule. Conversion to ultrasound phacoemulsification was required in 13 cases. Suitable fiber materials for Er:YAG laser delivery are sapphire, zirconium fluoride, silica, and germanium oxide. Toxicity of the latter is under investigation. CONCLUSION: The Er:YAG laser emulsified the lens nucleus safely and effectively. These early results include a higher than acceptable posterior capsule rupture rate and reflect the surgeon's learning curve with a new technology. Effective power delivery can be achieved with sapphire- and zirconium-fluoride-based fiber optics through a silica tip. The optimal energy delivery system has not been determined.

Aged↗

PubMed1982

Metabolic energy demand and optimal walking speed in post-polio subjects with lower limb afflictions.

The metabolic demand, using the relationship between speed and energy cost, and the optimal speed of walking, estimated by means of speed and energy cost per unit distance travelled, were studied in 16 post-polio subjects with lower limb affliction and 20 normal subjects with sedentary habits. It was observed that the post-polio subjects consumed higher energy than the normal persons at each walking speed between 0.28 and 1.26 m/s. The optimal speed of walking in post-polio subjects was lower than that of the normal persons and was associated with a higher energy demand per unit distance travelled. It was deduced that the post-polio subjects. not having used any assistive devices for a long time, have acquired severe degrees of disability which not only hindered their normal gait but also demanded extra energy from them.

Journal Article↗

PubMed2003

A flexible nudged elastic band program for optimization of minimum energy pathways using ab initio electronic structure methods.

A driver program for carrying out nudged elastic band optimizations of minimum energy reaction pathways is described. This approach allows for the determination of minimum energy pathways using only energies and gradient information. The driver code has been interfaced with the GAUSSIAN 98 program. Applications to two isomerization reactions and to a cluster model for H(2) desorption from the Si(100)-2 x 1 surface are presented.

Journal Article↗