Segmental archwire mechanics.

Straight wire orthodontic methods cannot treat the significant compromises demonstrated in this article. These types of patients require a three-dimensional method of correction, which involves segmental orthodontics or a modified straight wire technique. This article will discuss how to use the information gathered from a three-dimensional evaluation of the stable mandibular/maxillary relationship using a diagnostic orthotic to treat to a three-dimensional balanced relationship. Structural and functional relationships exist between the final occlusal relationship and the function of the joints, muscles and upper quadrant that must be considered during orthodontic, orthopedic and restorative finalization procedures if long term permanence is to be obtained. This article demonstrates these relationships and provides a means to approximate the dentition to function in harmony with the associated structures.

Diagnostic orthotics to establish the functional mandibular-maxillary relationship for orthodontic corrections.

Under optimal anatomic and physiologic circumstances, there exists a harmonious and functional balance between the occlusion, muscles of mastication and joint relationships referred to as a functional bite relationship. A diagnosis and treatment to the habitual bite relationship is provided if the function of the joints, muscles and associated structures is determined to be normal. If compromises of form or function are determined, a diagnostic orthotic is an essential tool to evaluate why the habitual bite position is not the best functional bite position and to also help determine a better functional relationship to avoid tissue and system compromise. The benefit of the diagnostic orthotic is the ability to establish an arbitrary reversible diagnostic relationship, evaluate the tissue and system response to this new association over time, and determine if the new treatment position is better for the patient than the habitual bite association.

Effect of in ovo administration of insulin-like growth factor-I on composition and mechanical properties of chicken bone.

The influence of in ovo administration of insulin-like growth factor-I (IGF-I) on long bone growth (tibiae and femora) of 42-d-old broiler chickens was investigated. Eggs were divided into three groups: uninjected control, vehicle-injected control, and recombinant human (rh) IGF-I. Eggs were injected once with 100 microL vehicle (10 mM acetic acid and 0.1% BSA) per embryo or vehicle containing 100 ng rh IGF-I/100 microL per embryo (n = 555 eggs total) on Days 1, 2, 3, or 4 of embryonic development. Males had greater bone length and moment of inertia than did females for the tibia and the femur (P < or = 0.01 for all). Although fracture load was significantly affected by gender (P < or = 0.02 and P < or = 0.006 for the femur and tibia, respectively), there was no treatment effect on these variables. However, when the fracture load was normalized with body weight of the animal, treatment and gender effects were found for femora (P < or = 0.04). Hydroxyproline concentrations of bones from male broilers were increased by the treatment (P < or = 0.02), whereas it had no effect on female broilers. There was no treatment effect on ash content, stiffness, yield load, yield deflection, and ultimate deflection and elastic, plastic, and total work for the femur or the tibia. We suggest that the effect of in ovo administration of IGF-I on bone mechanical properties was site-specific, and treated femora tended to have a lower fracture load relative to increased body weight.

Postnatal growth of broilers in response to in ovo administration of chicken growth hormone.

The effect of in ovo administration of chicken growth hormone (cGH) on growth rate and efficiency of gain, organ, and long bone growth of 42-d-old broiler chickens was investigated. Eggs were injected once with 100 microL vehicle (0.03 M NaHCO3, 0.15 M NaCl, pH 8.3) per embryo or vehicle containing 100 ng cGH/100 microL per embryo (n = 630 eggs total) on one of the following Days: 1, 4, or 7 through 18 of embryogenesis. There was no significant difference in hatchability between control and cGH treatment groups on any given injection day. Cumulative feed conversion of all treatment groups was improved relative to their respective control groups (P < 0.05). In ovo administration of cGH on Day 15 or 16 of incubation increased body weights (P < 0.01) of female broilers. On the other hand, body weights of male broilers were significantly increased by treatment on Day 1 (P < 0.04). Breast weights of female broilers from treatment groups Day 15 or 16 were increased (P < 0.01, P < 0.05, respectively). Liver weights of female broilers from treatment groups Day 1 and 15 were increased (P < 0.05, P < 0.01, respectively). In contrast, in ovo administration of cGH on Day 11 of incubation increased liver weights of male broilers (P < 0.03). There was no significant difference between control and treatment groups, in terms of heart or leg weights, or in Warner-Bratzler shear force of Pectoralis profundus muscle. Hydroxyproline concentration and cross-sectional area of female broiler tibias from treatment groups Day 11 or Day 16 were increased (P < 0.05), and ultimate breaking strength (stress) of tibias from the same groups was reduced (P < 0.05). In ovo administration of cGH altered growth and tissue development of broiler chickens in a time by sex dependent fashion.

The ontogeny of myostatin, follistatin and activin-B mRNA expression during chicken embryonic development.

The developmental pattern of myostatin, follistatin and activin-B genes in chick embryonic development was investigated. Total RNA was isolated from whole embryos on each of embryonic days (E) 0 to 6, from cranial halves of the embryo at E7 to 8, and from pectoralis muscle tissues at E9 to 20. Myostatin, follistatin and activin-B cDNAs were synthesized by reverse-transcription polymerase chain reaction (RT-PCR). Myostatin expression was first detected in embryos as early as the blastoderm stage (unincubated embryo, stage 1, E0). Myostatin mRNA concentration declined approximately 5 fold by E2 and remained lower through E6. Levels then increased 3 fold on E7 and plateaued through E16. Follistatin mRNA was first detected in the blastoderm stage of chick embryos. Overall follistatin mRNA increased 6 fold from E1 to E20 of development. Follistatin levels declined on E1 (approximately 2 fold) and remained low through E9. Follistatin mRNA reached the highest level prior to hatching. Activin-B mRNA from the whole embryo preparations (E0-E6) varied as the embryo matured. Overall activin-B gene expression from E11 to E20 appeared to decline (approximately 3.5 fold). This pattern is opposite of follistatin during the same period which is consistent with the opposing functions of these two proteins. We suggest that follistatin, activin-B and myostatin play an important role in embryogenesis and skeletal muscle development of the chick embryo. This study represents the first comprehensive report of myostatin mRNA patterns in chicken embryos.

Isolation and characterization of a calpain activator in chicken skeletal muscle.

The calpains (E.C. 3.4.22.17) and calpastatin constitute an ubiquitous, intracellular, Ca2+-dependent protease/inhibitor system. This system has been implicated as a principal regulator of myofibrillar protein degradation in both ante-mortem and postmortem muscle. Although proteolytic activity of the calpains is primarily controlled through interaction of calpain and calpastatin, evidence for an activator(s) has been limited and the reported characteristics varied. The function of the activator has not been elucidated. A putative calpain activator has been isolated from the Pectoralis muscle of broiler breeders (Cobb x Cobb). The activator elutes from an ion-exchange column at approximately 200 mM NaCl. Addition of activator increased apparent m-calpain activity to a level demonstrating a fourfold increase in proteolysis. The activator/calpain complex maintains a requirement for Ca2+ for proteolytic activity. Under physiological conditions, presence of the activator negates the ability of calpastatin to inhibit m-calpain. Additionally, the activator alone does not demonstrate proteolytic activity. Effect of the activator is pH-dependent; in a physiological pH range, the activator enhances m-calpain proteolytic activity but at pH less than 6.75 the effect is to inhibit m-calpain. The activator's ability to modulate m-calpain activity and eliminate calpastatin's effect provides a further means of regulating this important enzyme system.

In ovo administration of recombinant human insulin-like growth factor-I alters postnatal growth and development of the broiler chicken.

Two experiments assessed the efficacy of in ovo administration of insulin-like growth factor-I (IGF-I) to enhance skeletal muscle development and improve feed efficiency of broilers. Hatching eggs were divided into three groups: uninjected control, vehicle-injected control, and recombinant human (rh) IGF-I (100 ng per embryo). Eggs in Experiment 1 were injected on Day 1, 4, or one of Day 7 through 18 of incubation. Growth rates for Days 1 and 4 resulted in the greatest response to treatment (P < 0.01, P < 0.06 respectively). Based on these results, Experiment 2 focused on Days 1 to 4 of incubation. Results from Experiment 2 showed that there was no significant difference in hatchability among control and rh IGF-I treatment groups. Injection on Day 3 resulted in the greatest response for increased live (P < 0.035) and leg (P < 0.02) weights in both sexes. Feed efficiencies of all rh IGF-I groups were significantly (P < 0.01) improved for the first 3 wk. In ovo administration of rh IGF-I on Day 3 increased feed efficiency (6.65%; P < 0.009) in pens of mixed-sex broilers. In addition, live weights (12.3%; P < 0.002), leg weights (11.7%; P < 0.01), breast weights (9.9%; P < 0.04), and heart weights (11.4%; P < 0.02) were increased in males. These results demonstrate that in ovo administration of rh IGF-I alters feed efficiency, growth, and tissue development. This finding lends itself to significant improvements in broiler production efficiency and profitability.

Orthotics and orthodontics.

Many doctors think of orthotics or occlusal splints in connection with temporomandibular joint dysfunction patients and treatments. Few think of occlusal splints or intraoral orthotics in conjunction with orthodontics as diagnostic instruments. This article will demonstrate a close association between intraoral orthotics for diagnostic purposes to establish a functional mandibular-maxillary relationship before or during orthodontic treatment. Orthotics allow the practitioner to establish and maintain a harmony between the joint structures, the muscles and the dentition. Orthotics establish the stable orthopedic relationship prior to orthodontic intervention and thus, the end point of treatment established prior to irreversible corrections and a diagnosis of cause-effect relationships can be determined. Properly relating the mandible to the maxilla allows the opportunity to determine the arch developmental requirements necessary to maintain this functional relationship.

Interleukin-11 inhibits adipogenesis and stimulates myelopoiesis in human long-term marrow cultures.

Interleukin-11 (IL-11) is a bone marrow (BM) stromal-derived growth factor that has been shown to stimulate murine myeloid and lymphoid cells both in vitro and in vivo and to inhibit adipogenesis in a murine fibroblast cell line. We have studied the effects of IL-11 on highly purified human BM stem and progenitor cells and on human long-term marrow cultures (LTMC). Adipocyte differentiation is an integral component of murine and human LTMC. IL-11 stimulates myeloid growth as a single cytokine when added to highly enriched CD34+, HLA-DR+ bone marrow cells. IL-11 stimulated no growth in the more primitive CD34+, HLA-DR- population even in the presence of additional cytokines. IL-11 addition to human LTMC resulted in the expansion of myeloid and mixed, but not erythroid, progenitor populations. IL-11 dramatically increased the adherent cell populations, including both stromal cells and macrophages. Treated cultures also showed marked inhibition of fat accumulation in the adherent cells due in part to a block in the differentiation of preadipocytes to adipocytes, as shown by RNA analysis using adipocyte-specific markers. These data show that IL-11 stimulates a more differentiated, although multipotential, progenitor cell in human BM and that LTMC provide a useful model for studying the effects of this cytokine in the context of the hematopoietic microenvironment.

Human cord blood cells as targets for gene transfer: potential use in genetic therapies of severe combined immunodeficiency disease.

Human cord blood (CB) contains large numbers of both committed and primitive hematopoietic progenitor cells and has been shown to have the capacity to reconstitute the lympho-hematopoietic system in transplant protocols. To investigate the potential usefulness of CB stem and progenitor cell populations to deliver new genetic material into the blood and immune systems, we have transduced these cells using retroviral technology and compared the efficiency of gene transfer into CB cells with normal adult human bone marrow cells using a variety of infection protocols. Using two retroviral vectors which differ significantly in both recombinant viral titers and vector design, low density CB or adult bone marrow (ABM) cells were infected, and committed progenitor and more primitive hematopoietic cells were analyzed for gene expression by G418 drug resistance (G418r) of neophosphotransferase and protein analysis for murine adenosine deaminase (mADA). Standard methylcellulose progenitor assays were used to quantitate transduction efficiency of committed progenitor cells, and the long term culture-initiating cell (LTC-IC) assay was used to quantitate transduction efficiency of more primitive cells. Our results indicate that CB cells were more efficiently transduced via retroviral-mediated gene transfer as compared with ABM-derived cells. In addition, stable expression of the introduced gene sequences, including the ADA cDNA, was demonstrated in the progeny of infected LTC-ICs after 5 wk in long-term marrow cultures. Expression of the introduced ADA cDNA was higher than the endogenous human ADA gene in the LTC-IC-derived colonies examined. These studies demonstrate that CB progenitor and stem cells can be efficiently infected using retroviral vectors and suggest that CB cells may provide a suitable target population in gene transfer protocols for some genetic diseases.

Eminence-posterior occlusal plane angle in patients with temporomandibular disorders.

The causes of temporomandibular disorder are not clearly understood. The controversy regarding the role of the features, either dental or skeletal, still exists after nearly a half century of debate. The present study demonstrates an interesting correlation, expressed as an angular value, between the posterior surface of the articular eminence and the posterior occlusal plane. The group with dysfunction had a mean value significantly lower (133 +/- 4) than the group without symptoms (144 +/- 5). In light of this data, it is suggested to interpret a small eminence-posterior occlusal plane as an anatomical predisposing pattern for dysfunction.