Alternative Gramineous Hosts of Leptosphaeria nodorum Including Two New Records for the U. S. A.

Repeated trunk injections of tetracycline hydrochloride and oxytetra-cycline over a 27 month period, retarded the rate at which clove trees in Zanzibar, died from sudden death (SD) disease. This result provides additional support for an MLO aetiology for SD, but indicates that the tetracycline formulations and method of application, as described here, is not a feasible method of SD control in the field. Bioassay of leaf discs and root sections using agar plates seeded with Bacillus subtilis, at various times after injection, indicated that antibiotic distribution to the canopy was extensive, but that down to the roots was minimal. The proportion of leaf discs showing tetracycline activity declined over a 54 day period post-injection, from 75,% to 17%. Mean tetracycline levels in leaves per tree peaked at 2.4 μg/ml, 21 days after injection. The highest individual leaf disc level was 7 μg/ml. Most trees maintained concentrations of tetracycline inhibitory to B. subtilis growth for 2,1–41 days.     

Kinetics of fluid-phase pinocytosis in Dictyostelium discoideum amoebae

Kinetics of pinocytosis in Dictyostelium discoideum were investigated over an extended period of time (up to 6 hours) using fluorescein isothiocyanate (FITC)-dextran as a fluid-phase marker. FITC-dextran added to the medium accumulated rapidly inside the cells with a rate of influx equivalent to 9 microns3 of fluid/cell x min. After a period of about 90 min of uptake, the intracellular FITC-dextran level reached a plateau which corresponded to a strict balance between pinocytosis and exocytosis as shown both by efflux measurements and pulse experiments with (3H) dextran. At equilibrium, the amount of internalized marker reached a value equivalent to 790 microns3 of fluid taken up per amoeba, i.e. a volume paradoxically higher than the total aqueous space of the cell (520 microns3 ). FITC-dextran was thus markedly concentrated intracellularly. The endocytic compartment in which the intracellular FITC-dextran was concentrated could be completely washed out when FITC-dextran was removed from the external medium.     

Kinetics of follicle growth in the prepubertal gilt.

Follicular growth rates were determined by histological examination of ovaries of five prepubertal gilts following treatment with the stathmokinetic agent colchicine. One ovary from each of five gilts was removed surgically and then colchicine (n = 3) or saline (n = 2) was infused i.v. Precisely 2 h after treatment with colchicine, the remaining ovary was removed. Ovaries were processed for histological analyses and sectioned at 10 microns; every twentieth section was stained with hematoxylin and periodic acid-Schiffe's. Sections were viewed with a projection microscope and individual follicles were measured. Eight classes of follicles were established such that the number of granulosa cells per cross section doubled in each class. Diameters of follicles for each class were as follows: 1) less than 106 microns, 2) 106-148 microns, 3) 148-206 microns, 4) 206-287 microns, 5) 287-400 microns, 6) 400-657 microns, 7) 657-1480 microns, and 8) 1480-3130 microns. A layer of thecal cells was first seen in class 2 follicles, and 76% of class 3 follicles had a thecal layer. Oocyte diameter increased through the first four classes and reached a maximum diameter of approximately 110 microns. Almost all follicles greater than 400 microns had an antrum. Preantral follicles had a lower mitotic index and a higher mitotic time and class time than antral follicles. Growth rate increased with increasing size of follicles. Preantral follicles grew at a rate of 5.2 microns/day whereas antral follicles grew at 313 microns/day.(ABSTRACT TRUNCATED AT 250 WORDS)     

How is the flagellar length of mature sperm determined? I. Comparison of flagellar growth in spermatids between newt and Xenopus in vitro

The kinetics of flagellar growth in round spermatids were compared between Xenopus laevis and Cynops pyrrhogaster in vitro, the latter of which has about 13 times longer flagella in mature sperm than the former. In both species, more than 90% of the spermatids derived from marked primary spermatocytes grew flagella. In Xenopus the average flagellar length increased to 28 microns by the 6th day and then stopped growth, while in the newt, flagellar growth did not stop until reaching 107 microns in average on the 10th day. Maximal length was 36-38 microns in Xenopus and 187 microns in the newt. Two major differences in kinetics of flagellar growth were found between the two species. First, the initial rate of growth in the newt was about double the rate in Xenopus. Second, the period of flagellar growth in the newt (10 days) was also about double the period in Xenopus (5-6 days). Actinomycin D (10 micrograms/ml) had no inhibitory effect on flagellar growth in either species, whereas cycloheximide (10 microM) inhibited flagellar growth by more than 80% in both species. These results indicate that translational control presumably of flagellar protein synthesis plays an important role in flagellar growth in both species and in the difference in flagellar length in spermatids between Xenopus and newt.     

Dissociation between metabolic and vascular insulin resistance in aging

Physiological actions of insulin via activation of the phosphatidylinositol 3-kinase/Akt pathway in the endothelium serve to couple regulation of hemodynamic and metabolic homeostasis. Insulin resistance, endothelial dysfunction, and hypertension increase in prevalence with aging. We investigated the metabolic and endothelial actions of insulin in 24- vs. 3-mo Sprague-Dawley rats. With the use of the hyperinsulinemic euglycemic clamp, the rate of glucose infusion necessary to maintain equivalent plasma glucose (5.5 mmol/l) was similar in 24- vs. 3-mo rats, as was fasting glucose (5.2 +/- 0.33 vs. 4.4 +/- 0.37 mmol/l; mean +/- SE) and insulin (0.862 +/- 0.193 vs. 1.307 +/- 0.230 mg/l). Systolic blood pressure was higher in 24-mo rats (133 +/- 5 vs. 110 +/- 4 mmHg; P = 0.005). Endothelial nitric oxide (NO)-dependent relaxation to insulin was impaired in aortas of 24- vs. 3-mo rats (maximal response 8.9 +/- 4.3 vs. 34.9 +/- 3.9%; P = 0.002); N(G)-nitro-l-arginine methyl ester abolished insulin-mediated relaxation in 3- but not 24-mo rats. Endothelium NO-dependent (acetylcholine) and -independent (sodium nitroprusside) relaxation, as well as NADPH oxidase activity, were similar in 3- and 24-mo rats. Insulin increased aortic serine phosphorylation of Akt in 3-mo rats by 120% over 24-mo rats (P < 0.05) and serine phosphorylation of endothelial NO synthase (eNOS) in 3-mo rats by 380% over 24-mo rats (P < 0.05). Aortic expression of phosphorylated c-Jun NH(2)-terminal kinase-1 and serine phosphorylated insulin receptor substrate-1, known mediators of metabolic insulin resistance, was similar in 3- and 24-mo rats. Expression of caveolin-1, a regulator of eNOS activity and insulin signaling, was 55% lower in 24- than 3-mo rats (P = 0.002). In summary, impaired vasorelaxation to insulin in aging was independent of metabolic insulin sensitivity and associated with impaired insulin-mediated activation of the Akt/eNOS pathway, but intact activation of the acetylcholine-mediated Ca(2+)-calmodulin/eNOS pathway. Vascular insulin resistance in aging may add to the increased susceptibility of this population to vascular injury induced by traditional cardiovascular risk factors.     

The Effect of Tetracycline upon Establishment of Escherichia coli of Bovine Origin in the Enteric Tract of Man

S ummary . Human volunteers were given orally 0, 50 or 1000 mg of tetracycline/day for the 4 days preceding and the 5 days following ingestion of 1–2 x 10⁶ cells of tetracycline resistant Escherichia coli strain x-314 of bovine origin. Of those receiving 0, 50 or 1000 mg of tetracycline/day, 9/13, 5/9 and 12/13, respectively, excreted the organism at least once during the 25-day sampling period. Significant differences were not observed between subjects receiving 0 or 50 mg of tetracycline/day with respect to the length of time the coliform was recovered from faeces, or the maximum proportion of the total coliforms found to be E. coli x-314. Those receiving 1000 mg of tetracycline/day shed E. coli x-314 for longer periods and the latter's contribution to the coliform population was greater than in those subjects receiving 0 or 50 mg of tetracycline/day. It was concluded that 1000, but not 50 mg, of tetracycline/day taken orally potentiates the establishment of a tetracycline resistant E. coli in the enteric tract of man.     

Continuous cultivation and improved drug responsiveness of Plasmodium falciparum in p-aminobenzoic acid-deficient medium

Long term cultivation of three culture lines of Plasmodium falciparum was achieved in Waymouth and RPMI media, both supplemented with 10% heat-inactivated human serum. Observations on parasite multiplication over a 6-mo period showed no difference in the rate of parasite population increase. Growth of asexual erythrocytic stages in Waymouth medium was as good as that in RPMI when measured by the rate of glucose utilization and extent of 3H-isoleucine and 3H-methionine incorporation. Responsiveness of the parasites to pyrimethamine and sulfadoxine was demonstrated to increase when tested in Waymouth medium because it contained no p-aminobenzoic acid to compete with the drugs.     

Growth, development and allometry of Philophthalmus nocturnus in the eyes of domestic chicks.

Fifty day-old chicks were each infected with 10 excysted metacercariae of Philophthalmus nocturnus Looss, 1907 around each orbit and growth, development and allometry were studied. The growth rate showed two phases over a period of 35 days, a limited lag phase lasting two days post-infection in which flukes did not exceed 440 microns in length, and a rapid phase during which growth was rapid and flukes reached a size of 3.008-3.504 mm on day 35. Five developmental stages were noticed during the course of development of the metacercaria to the egg-producing adult stage. Eggs appeared in the uterus on day 14 and oculate miracidia on day 25. The hindbody, testes and ovary showed positive allometric growth, the pharnyx less so, whereas negative allometric growth was shown by the forebody. Body width, oral sucker and ventral sucker were close to isometry, growing at the same rate as the body length.     

Influence of Lernaeocera branchialis (Crustacea: Copepoda) on growth rate of Atlantic cod, Gadus morhua

Influence of Lernaeocera branchialis, a hematophagous copepod, on the growth rate of Atlantic cod, Gadus morhua, was investigated in fish of various sizes. Initially, it appeared that growth, over a 16-mo period, was reduced when single or multiple infections were present. We then examined growth rate by comparing food consumption, weight gain, food conversion efficiency, and condition (k) factor over a 2-mo period and subsequently over a 4 wk in control and experimentally infected fish. Total body weight and length of each fish, controls and infected were determined before and after feeding known weights of food. Adults infected with young parasites consumed more food and gained more weight than controls, especially in the first month, but food conversion efficiency and k-factor were greater than those of controls after 2 mo, but food efficiency was still lower than in controls. In 2 groups of young infected fish, all values were consistently lower than those of uninfected fish of comparable size during the 2-mo period. Three additional trials on immature cod confirmed that infected fish consumed less food and exhibited less growth than infected controls. Our results suggest that only adult cod infected with immature parasites compensate for the infections by increasing food consumption, thus resulting in a transitory weight gain. Additionally, parasites that have completed their reproductive activities still produce subtle effects in the form of low food conversion efficiency in their hosts.     

Changes in nurse cell nuclei during synchronous infection with Trichinella spiralis

The rate of enlargement of nuclei was determined on 4-microns-thick sections of synchronously infected mouse thigh muscle. Normal muscle nuclei had a geometric mean volume of 84 microns and a range of 42-170 microns 3. At days 5, 6, 7, 8, and 10 and 6 mo after infection, mean nuclear volume was 177 (100-315) microns 3, 254 (140-462) microns 3, 278 (172-447) microns 3, 681 (407-1,138) microns 3, 512 (326-804) microns 3, and 509 (298-870) microns 3, respectively. Size of nuclei for any given day followed a log normal distribution. On days 7 and 8 after infection, 31% of enlarged nuclei had 2 nucleoli, whereas only 15% had 2 nucleoli on day 10. One percent of enlarged nuclei in 6-mo-old nurse cells had double nucleoli. The number of enlarged nuclei in 6-mo-old nurse cells was determined from serial sections of infected tongue muscle. Each nurse cell contained an average of 40 enlarged nuclei. Sixty-four percent of nurse cells examined (n = 55) had between 30 and 60 enlarged nuclei. However, there was great variation in the range (7-142). These results are discussed in relation to the development of the nurse cell.     

Fluorochrome labelling in Roman period skeletons from Dakhleh Oasis, Egypt

A histological aging study of femoral midshafts in a late Roman period sample from the Dakhleh Oasis, Egypt, showed discrete fluorochrome labelling. The fluorochrome is yellow-green in colour and fluoresces at a wavelength of 525 nm. The labelling occurs at the mineralization fronts and is so distinct that several histomorphometric measurements were made. The percent labelled surface values ranged from 6.03% to 59.34%, and the mean distance between labels ranged from 13.57 to 20.63 microns. Teeth from several individuals were also labelled within the enamel matrix. Comparisons were made between the patterns of fluorescent labelling from this population and from patients treated with interval and continuous dosages of tetracycline. The results collectively indicate that the fluorochrome is most likely tetracycline that made its way into the bone (in vivo) via stored grain contaminated by Streptomycetes. The labelling was differential, much like that of the patient on interval doses of tetracycline, so it is argued that the tetracycline was ingested occasionally, probably on a seasonal basis. The lack of bone infection in the adults (n = 29) suggests that the tetracycline may have provided some antibiotic protection in this population.     

Retention of nickel oxide (green) aerosol in rat lungs by long-term inhalation

Wistar male rats were exposed to green nickel oxide [NiO(G)] aerosols (mass median aerodynamic diameter, 0.6 μm) for 7 h/d, 5 d/wk for up to 12 mo. The average exposure concentration was controlled at 0.3 mg/m³ and 1.2 mg/m³ during the exposure period. Some rats were sacrificed just after the 3- and 6-mo exposures, and others were sacrificed after the termination of the 12-mo exposure. There were no differences in body weight gain between NiO(G) exposure groups and controls. The lung weights in the exposed rats were heavier than those in the control ones. Nickel concentrations in lungs of exposure groups were much higher than those of controls. The nickel concentrations in liver, kidney, spleen, and blood slightly increased with the passing of the exposure time. The nickel content in rat lungs during the 12-mo exposure was estimated theoretically. The estimated values agreed with the experimental data. This result shows that the clearance rate increases with the decreasing of the particle diameter.     

ORPHAN-INDUCED LACTATION IN TURSIOPS AND ANALYSIS OF COLLECTED MILK

Two non-lactating, non-gravid female bottlenose dolphins, Tursiops truncatus , (SLA, age 32 yr and TOD, age 34 yr) began lactating within one week after being housed with a 6.5- and 6.75-month-old orphaned calf, respectively. Cooperative swimming and nursing behaviors were quickly evident in both cow/ calf pairs. During the first 2.5 mo a milk substitute, eventually in combination with some whole fish, was used to supplement nursing in both calves. After this initial period, supplemental feeding was discontinued. SLA then became her adopted calf s sole source of nutrition for the next 5 mo, followed by another 6 mo during which the calf shifted to a predominantly fish diet with occasional nursing. TOD's orphan also continued to nurse beyond the 2.5-mo supplementation period and began voluntarily accepting small quantities of fish, suckling continued over the next year while fish consumption increased. Using a modified human breast pump, trainers collected milk at intervals from the adult dolphins throughout the lactation period. The first milk collected from TOD (day 8 after housing with calf) and SLA (day 12 with her calf) contained 6.0% and 10.3% fat, respectively. On day 68 TOD's milk fat had increased to 23.5%, and on day 37 that of SLA measured 22.5%. These later values are similar to those reported for normally lactating bottlenose dolphins.     

Deoxyribonucleic Acid synthesis in root cap cells of cultured roots of convolvulus

Isolated cultured roots of Convolvulus arvensis L. were incubated in 0.2 microcurie per milliliter methyl-³H-thymidine for 14 hours, for 64 hours, or for 14 hours followed by transfer to fresh nutrient medium without tritiated thymidine. Autoradiographs of serial, longitudinal sections of roots which were continuously incubated with tritiated thymidine showed that cells of the root cap columella did not undergo DNA synthesis after their formation from the root cap initials. In roots pulse-labeled with tritiated thymidine, the movement of labeled cells through the root cap columella was followed. Labeled cells were displaced at a constant rate of 72 microns per day over a period of 6 to 9 days before they were sloughed off from the root cap. The specialized role of the root cap cells in relation to their distinctive metabolism and longevity is discussed.     

Experimental activation of cryptosporidiosis in mice by immunosuppression

Cryptosporidium, a coccidian parasite first described by Tyzzer (1907) from a laboratory mouse, has become an important human enteric pathogen causing overwhelming diarrhea especially in immunocompromised patients such as AIDS. This parasite has been reported from over 20 countries and is recognized as a cosmopolitan species. In Korea, however, there has been no report on human as well as animal cryptosporidiosis. This study was performed so as to verify the presence of Cryptosporidium in Korea by activating the parasite from laboratory mice by immunosuppression. Total 65 conventionally-bred ICR mice including a control (5 mice) and 3 experimental groups (20 each) were used for this study. Group I was immunosuppressed with prednisolone injection (1 mg IM, every other day) for 7 weeks. Group II (prednisolone injection and tetracycline administration) and Group III (prednisolone injection and trimethoprim-sulfamethoxazole administration) were prepared to observe the effect of antibacterial agents on the activation of cryptosporidiosis. In fecal examinations of mice Cryptosporidium oocysts (4-6 microns in size) were detected from 1 week after the start of immunosuppression and the mice began to die. In H-E stained tissue sections of the lower jejunum, numerous very small (2-4 microns), dense, ovoid or spherical, slightly basophilic bodies were seen attached on the free border of mucosal epithelial cells. In scanning and transmission electron microscopic observations, these organisms were identified as various developmental stages of Cryptosporidium. The species is considered to be C. parvum.(ABSTRACT TRUNCATED AT 250 WORDS)     

Resistance training increases total daily energy expenditure in disabled older women with coronary heart disease.

Physical activity energy expenditure (PAEE) is a determinant of prognosis and fitness in older patients with coronary heart disease (CHD). PAEE and total energy expenditure (TEE) are closely related to fatness, physical function, and metabolic risk in older individuals. The goal of this study was to assess effects of resistance training on PAEE, TEE, and fitness in older women with chronic CHD and physical activity limitations (N = 51, mean age: 72 + 5 yr). The study intervention consisted of a progressive, 6-mo program of resistance training vs. a control group condition of low-intensity yoga and deep breathing. The study interventions were completed by 42 of the 51 participants. The intervention group manifested a 177 +/- 213 kcal/day (+9%) increase in TEE, pre- to posttraining, measured by the doubly labeled water technique during a nonexercise 10-day period (P < 0.03 vs. controls). This was due to a 50 +/- 74 kcal/day (4%) increase in resting metabolic rate measured by indirect calorimetry (P < 0.01, P < 0.05 vs. controls) and a 123 +/- 214 kcal/day (9%) increase in PAEE (P < 0.03, P = 0.12 vs. controls). Resistance training was associated with significant increases in upper and lower body strength, but no change in fat-free mass, measured by dual X-ray absorptiometry, or left ventricular function, measured by echocardiography and Doppler. Women in the control group showed no alterations in TEE or its determinants. There were no changes between groups in body composition, aerobic capacity, or measures of mental depression. These results demonstrate that resistance training of 6-mo duration leads to an increase in TEE and PAEE in older women with chronic CHD.     

Quantitative determination of follicle size distribution in the guinea pig ovary after hemicastration and PMSG treatment

In order to investigate the action point of intraphysiological or supraphysiological elevation of FSH during the preovulatory period on follicular development, adult guinea pigs underwent unilateral ovariectomy on days 10, 12 and 14 of the estrous cycle (N = 6 each group). Thereafter, guinea pigs were injected twice daily with either vehicle or pregnant mare's serum gonadotropin (PMS). After 2 days, the remaining ovaries were removed. The resected ovaries were fixed, embedded in paraffin, serially sectioned (7 microns) and stained with Azan. All follicles greater than 70 microns were classified by size and atretic stage. The follicular size distribution was not affected by hemicastration at day 10, although the ratio of atretic follicles (greater than 400 microns) decreased from 51% to 32% (P less than 0.01). Hemicastration at day 12 increased the largest nonatretic population (70-99 microns group) from 17% to 26%, and the ratio of atretic follicles (greater than 400 microns) decreased from 35% to 23%. The peak size distribution of follicles was shifted from 70-99 microns to 200-299 microns by PMS, and follicles 600-899 microns in size contained an increased percentage of atresia, which resulted in the bimodal distribution of viable follicles greater than 400 microns. These data suggest that 2 day hemicastration promotes an influx of primordial follicles into growing follicles and suppresses the atretic process by a different mechanism depending on the date of hemicastration in the estrous cycle. Conversely, hemicastration + PMS accelerated viable follicle growth to increase the percentage of atresia.     

Male Masturbation in Free-Ranging Japanese Macaques

We studied masturbatory behavior of males over a 14-mo period in free-ranging Japanese macaques (Macaca fuscata yakui) on Yakushima island, Japan. We distinguished 2 types: (1) masturbation only and (2) masturbation with final ejaculation. Both types occurred in all 15 adult troop males. We calculated masturbation only as an index (M/h). It occurred over the whole year; however, it was more frequent during the mating than during the non-mating periods. Masturbation with ejaculation was restricted to the mating period. Male mating success correlated positively with social status. Both rate of masturbation only and masturbatory ejaculations increased as male social status and male mating success declined. Lower-ranking males had higher rates of masturbation only, i.e., they spent more time masturbating than higher-ranking males did. Lower-ranking males also had higher proportions of ejaculates for masturbation, while higher-ranking males used most of their ejaculates for mating.     

Effect of clomiphene citrate on the ovary of a wild rat, Bandicota bengalensis

The effects of clomiphene citrate (0.3 or 3.0 mg/kg body weight/day) for 10 consecutive days on the ovary of a wild rat, Bandicota bengalensis, were studied. The low dose of clomiphene decreased the number of nonatretic follicles larger than 400 microns in diameter, increased atresia in follicles smaller than 200 microns, inhibited granulosal mitosis in follicles less than 200 microns and between 401 and 600 microns in diameter and inhibited thecal mitosis in follicles smaller than 400 microns and larger than 600 microns. The high dose of clomiphene increased the number of follicles between 201 and 400 microns, decreased the number of follicles larger than 600 microns, increased atresia in follicles of 51-400 microns and increased granulosal mitosis in follicles of 201-400 microns diameter. In both the doses, clomiphene inhibited the ovulation rate (p less than 0.005), with 25 and 35% of the rats being anovulatory in low and high doses, respectively. In addition, clomiphene caused irregularity in the estrous cycles associated with increased cycle length. These results suggest that the clomiphene-induced partial inhibition of ovulation is possibly through its action on follicular growth and atresia mainly in nonantral (less than 200 microns) and mature follicles (401-600 microns).     

Callus stimulation in distraction osteogenesis

Distraction osteogenesis has been described as in vivo tissue engineering. The ability to stimulate this process for the repair of bony defects or lengthening of congenitally shortened facial structures is likely to significantly impact the field of craniofacial surgery. The purpose of this study was to determine whether mechanical stimulation of the distracted rabbit mandible would accelerate the maturation of the bony callus when applied during the early consolidation period. Twenty adult New Zealand White rabbits underwent unilateral mandibular osteotomy. A uni-directional internal distractor device (Synthes, Paoli, Pa.) was positioned along a plane perpendicular to the line of osteotomy. After a 7-day latency period, distraction was commenced at a rate of 1.0 mm/day for 12 days in all animals. In a control group of 10 rabbits, a consolidation period of 8 weeks was observed before they were killed. In the experimental group of 10 rabbits, daily alternate compression and distraction of 1 mm (sequential compression and distraction) was performed for 3 weeks followed by a 5-week period of rigid fixation. Each animal received a dose of a fluorescent label at three different time points during the study: at the end of the distraction period, 3 weeks after the completion of the distraction phase, and 3 days before it was killed. All animals were killed 8 weeks after the completion of the distraction phase. Undecalcified histologic analysis and 3-point bending tests to failure were performed on the extracted mandibles. The results of the experimental and control groups were compared.Four animals in the control group and three animals in the experimental group were excluded from the study because of screw loosening resulting in distractor dislodgment or because of infection. On histologic analysis, cortical thickness at the center of the callus was found to be significantly greater in the experimental group compared with the control group when normalized to the contralateral hemimandible (83 percent versus 49 percent, respectively; p < 0.007). The ratio of cortical to cancellous bone in the distracted callus was uniformly found to be greater in the experimental specimens. The mineral apposition rate was calculated by using fluorescence microscopy and found to be significantly greater in the experimental group both during the period of sequential compression and distraction (3.2 microm/day versus 2.1 microm/day, p = 0.02) and after the period of sequential compression and distraction (1.4 microm/day versus 1.1 microm/day, p = 0.006). Mechanical testing revealed no significant differences in bending strength or stiffness between experimental or control groups (p = 0.54 and 0.47, respectively). This study has demonstrated that daily alternating compression and distraction of 1 mm amplitude during the early consolidation period has a stimulatory impact on callus formation with respect to osteoblastic activity, remodeling, and maturation of bone. Optimal timing and amplitude of sequential movement, long-term biomechanical differences, and molecular pathways have yet to be elucidated.