Exceptional Changes in Skeletal Anatomy under Domestication: The Case of Brachycephaly.

"Brachycephaly" is generally considered a phenotype in which the facial part of the head is pronouncedly shortened. While brachycephaly is characteristic for some domestic varieties and breeds (e.g., Bulldog, Persian cat, Niata cattle, Anglo-Nubian goat, Middle White pig), this phenotype can also be considered pathological. Despite the superficially similar appearance of "brachycephaly" in such varieties and breeds, closer examination reveals that "brachycephaly" includes a variety of different cranial modifications with likely different genetic and developmental underpinnings and related with specific breed histories. We review the various definitions and characteristics associated with brachycephaly in different domesticated species. We discern different types of brachycephaly ("bulldog-type," "katantognathic," and "allometric" brachycephaly) and discuss morphological conditions related to brachycephaly, including diseases (e.g., brachycephalic airway obstructive syndrome). Further, we examine the complex underlying genetic and developmental processes and the culturally and developmentally related reasons why brachycephalic varieties may or may not be prevalent in certain domesticated species. Knowledge on patterns and mechanisms associated with brachycephaly is relevant for domestication research, veterinary and human medicine, as well as evolutionary biology, and highlights the profound influence of artificial selection by humans on animal morphology, evolution, and welfare.

La braquicefalia generalmente se considera un fenotipo en el que el cráneo, específicamente el hocico, es notablemente acortado. Mientras que la braquicefalia es característica de algunas variedades domésticas y razas (p.e. Bulldog, gato persa, vaca ñata, cabra anglo nubiana, cerdo Middle White), también se puede interpretar como un fenotipo patológico. A pesar de que la braquicefalia tiene una apariencia semejante, por lo menos superficial, en estas variedades y razas, al examinarla más en detalle se descubre que la "braquicefalia" incluye una variedad de diferentes modificaciones del cráneo que probablemente tienen diferentes subyacentes genéticos y de desarrollo y que están relacionados con la historia de la raza. Revisamos las diferentes definiciones y propiedades relacionadas con la braquicefalia en varias especies domésticas. Describimos diferentes tipos de braquicefalia (tipo bulldog, "katantognático" y braquicefalia alométrica) y analizamos condiciones morfológicas relacionadas con la braquicefalia incluyendo enfermedades (p.e. síndrome obstructivo respiratorio). Además, examinamos los complejos procesos genéticos y de desarrollo subyacentes y los motivos culturales y de desarrollo por las que variedades braquicéfalas pueden ser más o menos prevalentes en ciertas especies domésticas. El conocimiento de patrones y mecanismos asociados a la braquicefalia son relevantes para la investigación sobre la domesticación, medicina veterinaria y humana, así como para la biología evolutiva y destaca la profunda influencia de la selección artificial sobre la morfología y bienestar de los animales y su evolución.

Small bowel toxicity after high dose spot scanning-based proton beam therapy for paraspinal/retroperitoneal neoplasms.

PURPOSE: Mesenchymal tumours require high-dose radiation therapy (RT). Small bowel (SB) dose constraints have historically limited dose delivery to paraspinal and retroperitoneal targets. This retrospective study correlated SB dose-volume histograms with side-effects after proton radiation therapy (PT). PATIENTS AND METHODS: Between 1997 and 2008, 31 patients (mean age 52.1 years) underwent spot scanning-based PT for paraspinal/retroperitoneal chordomas (81%), sarcomas (16%) and meningiom (3%). Mean total prescribed dose was 72.3 Gy (relative biologic effectiveness, RBE) delivered in 1.8-2 Gy (RBE) fractions. Mean follow-up was 3.8 years. Based on the pretreatment planning CT, SB dose distributions were reanalysed. RESULTS: Planning target volume (PTV) was defined as gross tumour volume (GTV) plus 5-7 mm margins. Mean PTV was 560.22 cm(3). A mean of 93.2% of the PTV was covered by at least 90% of the prescribed dose. SB volumes (cm(3)) receiving doses of 5, 20, 30, 40, 50, 60, 70, 75 and 80 Gy (RBE) were calculated to give V5, V20, V30, V40, V50, V60, V70, V75 and V80 respectively. In 7/31 patients, PT was accomplished without any significant SB irradiation (V5=0). In 24/31 patients, mean maximum dose (Dmax) to SB was 64.1 Gy (RBE). Despite target doses of >70 Gy (RBE), SB received >50 and >60 Gy (RBE) in only 61 and 54% of patients, respectively. Mean SB volumes (cm(3)) covered by different dose levels (Gy, RBE) were: V20 (n=24): 45.1, V50 (n=19): 17.7, V60 (n=17): 7.6 and V70 (n=12): 2.4. No acute toxicity ≥ grade 2 or late SB sequelae were observed. CONCLUSION: Small noncircumferential volumes of SB tolerated doses in excess of 60 Gy (RBE) without any clinically-significant late adverse effects. This small retrospective study has limited statistical power but encourages further efforts with higher patient numbers to define and establish high-dose threshold models for SB toxicity in modern radiation oncology.

Structured three-dimensional co-culture of mesenchymal stem cells with chondrocytes promotes chondrogenic differentiation without hypertrophy.

OBJECTIVE: This study investigated a novel approach to induce chondrogenic differentiation of human mesenchymal stem cells (hMSC). We hypothesized that a structured three-dimensional co-culture using hMSC and chondrocytes would provide chondroinductive cues to hMSC without inducing hypertrophy. METHOD: In an effort to promote optimal chondrogenic differentiation of hMSC, we created bilaminar cell pellets (BCPs), which consist of a spherical population of hMSC encased within a layer of juvenile chondrocytes (JC). In addition to histologic analyses, we examined proteoglycan content and expression of chondrogenic and hypertrophic genes in BCPs, JC pellets, and hMSC pellets grown in the presence or absence of transforming growth factor-ß (TGFß) following 21 days of culture in either growth or chondrogenic media. RESULTS: In either growth or chondrogenic media, we observed that BCPs and JC pellets produced more proteoglycan than hMSC pellets treated with TGFß. BCPs and JC pellets also exhibited higher expression of the chondrogenic genes Sox9, aggrecan, and collagen 2A1, and lower expression of the hypertrophic genes matrix metalloproteinase-13, Runx2, collagen 1A1, and collagen 10A1 than hMSC pellets. Histologic analyses suggest that JC promote chondrogenic differentiation of cells in BCPs without hypertrophy. Furthermore, when cultured in hypoxic and inflammatory conditions intended to mimic the injured joint microenvironment, BCPs produced significantly more proteoglycan than either JC pellets or hMSC pellets. CONCLUSION: The BCP co-culture promotes a chondrogenic phenotype without hypertrophy and, relative to pellet cultures of hMSCs or JCs alone, is more resistant to the adverse conditions anticipated at the site of articular cartilage repair.

Rhinovirus-induced modulation of gene expression in bronchial epithelial cells from subjects with asthma.

Rhinovirus (RV) infections trigger asthma exacerbations. Genome-wide expression analysis of RV1A-infected primary bronchial epithelial cells from normal and asthmatic donors was performed to determine whether asthma is associated with a unique pattern of RV-induced gene expression. Virus replication rates were similar in cells from normal and asthmatic donors. Overall, RV downregulated 975 and upregulated 69 genes. Comparisons of transcriptional profiles generated from microarrays and confirmed by quantitative reverse transcription PCR and cluster analysis showed some up- and downregulated genes in asthma cells involved in immune responses (IL1B, IL1F9, IL24, and IFI44) and airway remodeling (LOXL2, MMP10, FN1). Notably, most of the asthma-related differences in RV-infected cells were also present in the cells before infection. These findings suggest that differences in RV-induced gene expression profiles of cells from normal and mild asthmatic subjects could affect the acute inflammatory response to RV, and subsequent airway repair and remodeling.

The cells that fill the bill: neural crest and the evolution of craniofacial development.

Avian embryos, which have been studied scientifically since Aristotle, continue to persevere as invaluable research tools, especially for our understanding of the development and evolution of the craniofacial skeleton. Whether the topic is beak shape in Darwin's finches or signaling interactions that underlie bone and tooth formation, birds offer advantages for craniofacial biology that uniquely complement the strengths of other vertebrate model systems, such as fish, frogs, and mice. Several papers published during the past few years have helped pinpoint molecular and cellular mechanisms that pattern the face and jaws through experiments that could only have been done together with our feathered friends. Ultimately, such knowledge will be essential for devising novel clinical approaches to treat and/or prevent diseases, injuries, and birth defects that affect the human craniofacial skeleton. Here we review recent insights plucked from avians on key developmental processes that generate craniofacial diversity.

Amelogenins in human developing and mature dental pulp.

Amelogenins are a group of heterogenous proteins first identified in developing tooth enamel and reported to be present in odontoblasts. The objective of this study was to elucidate the expression and function of amelogenins in the human dentin-pulp complex. Developing human tooth buds were immunostained for amelogenin, and mRNA was detected by in situ hybridization. The effects of recombinant amelogenins on pulp and papilla cell proliferation were measured by Brd U immunoassay, and differentiation was monitored by alkaline phosphatase expression. Amelogenin protein was found in the forming dentin matrix, and amelogenin mRNA was localized in the dentin, presumably in the odontoblast processes. Proliferation of papilla cells was enhanced by recombinant human amelogenin rH72 (LRAP+ exon 4), while pulp cells responded to both rH72 and rH58 (LRAP), with no effect by rH174. These studies suggest that odontoblasts actively synthesize and secrete amelogenin protein during human tooth development, and that low-molecular-weight amelogenins can enhance pulp cell proliferation.

Cranial skeletal biology.

To artists, the face is a mirror of the soul. To biologists, the face reflects remarkable structural diversity--think of bulldogs and wolfhounds or galapagos finches. How do such variations in skeletal form arise? Do the same mechanisms control skeletogenesis elsewhere in the body? The answers lie in the molecular machinery that generates neural crest cells, controls their migration, and guides their differentiation to cartilage and bone.

The cellular and molecular origins of beak morphology.

Cellular and molecular mechanisms underlying differences in beak morphology likely involve interactions among multiple embryonic populations. We exchanged neural crest cells destined to participate in beak morphogenesis between two anatomically distinct species. Quail neural crest cells produced quail beaks in duck hosts and duck neural crest produced duck bills in quail hosts. These transformations involved morphological changes to non-neural crest host beak tissues. To achieve these changes, donor neural crest cells executed autonomous molecular programs and regulated gene expression in adjacent host tissues. Thus, neural crest cells are a source of molecular information that generates interspecific variation in beak morphology.

Preliminary data on the Multidimensional Fatigue Inventory-20 from female caregivers of male hemodialysis patients.

To test the reliability and concurrent validity of the Multidimensional Fatigue Inventory-20, 45 spouses or first-degree female caregivers of male hemodialysis patients in northern and eastern Iowa were administered the Multidimensional Fatigue Inventory-20 and the Rhoten Fatigue Scale. Four of the five subscales had a high Cronbach alpha (.76 to .82). There were low to moderate statistically significant Pearson correlations between scores on the Rhoten Fatigue Inventory and the MFI-20 subscales (.40 to .72). Limitations of generalizations are addressed.

Local retinoid signaling coordinates forebrain and facial morphogenesis by maintaining FGF8 and SHH.

Correlations between facial anomalies and brain defects are well characterized throughout the clinical literature, yet a developmental basis for this association has not been identified. We demonstrate that the frontonasal process, which gives rise to the mid- and upper face, and the forebrain are linked early in their morphogenesis by a local retinoid signaling event that maintains the expression of key regulatory molecules. First, we show that aldehyde dehydrogenase 6, which synthesizes the ligand, retinoic acid, is localized to the ventral epithelium of the presumptive frontonasal process of chick embryos. At least two retinoid receptors are expressed in adjacent populations of mesenchyme. Second, using synthetic pan-specific retinoid antagonists, we transiently inhibit the ability of retinoid receptors to bind retinoic acid in the rostral head and we generate embryos with a hypoplastic forebrain, fused eyes, and no frontonasal process-derived structures such as the upper beak. These defects are not due to eliminating mesenchymal progenitors, as neural crest cells still migrate into the frontonasal process, despite disruptions to retinoid signaling. Rather, these malformations result from loss of fibroblast growth factor 8 and sonic hedgehog expression, which leads to increased programmed cell death and decreased proliferation in the forebrain and frontonasal process. Most significantly, we can rescue the morphological defects by re-introducing retinoic acid, or fibroblast growth factor and sonic hedgehog proteins into antagonist-treated embryos. We propose that the local source of retinoic acid in the rostral head initiates a regulatory cascade that coordinates forebrain and frontonasal process morphogenesis.

Genetic and teratogenic approaches to craniofacial development.

Craniofacial malformations are the most common birth defects that occur in humans, with facial clefting representing the majority of these defects. Facial clefts can arise at any stage of development due to perturbations that alter the extracellular matrix as well as affect the patterning, migration, proliferation, and differentiation of cells. In this review, we focus on recent advances in the understanding of the developmental basis for facial clefting through the analysis of the effects of gene disruption experiments and treatments with teratogens in both chickens and mice. Specifically, we analyze the results of disruptions to genes such as Sonic hedgehog (Shh), epidermal growth factor receptor (EGFR), Distal-less (Dlx), and transforming growth factor beta 3 (TGFbeta3). We also describe the effects that teratogens such as retinoic acid, jervine, and cyclopamine have on facial clefting and discuss mechanisms for their action. In addition to providing insight into the bases for abnormal craniofacial growth, genetic and teratogenic techniques are powerful tools for understanding the normal developmental processes that generate and pattern the face.

Urine as a source of conspecific disturbance signals in the crayfish Procambarus clarkii.

Chemical signals are an important aspect of ecological interactions in crustacean systems. Repellent chemical signals can be classified into three context-specific categories: chemicals released directly from a repellent stimulus (avoidance chemicals), chemicals released from damaged conspecifics (alarm chemicals) and chemicals released from stressed but undamaged conspecifics (stress chemicals). Our study examines the existence and putative source of the stress signals in crayfish. We hypothesize that Procambarus clarkii can recognize stressed individuals through chemical signals and also that the source of the signal that provides P. clarkii with information on the behavioral state of the sender is the urine. We collected urine and gill water from stressed and non-stressed animals, and chemicals from damaged conspecifics. Chemical cues were introduced into a test arena while several behavior patterns of P. clarkii were recorded. Stressed crayfish produce significantly more urine than non-stressed crayfish, and this urine caused crayfish to walk significantly faster and farther and away from the source of the signal. These results demonstrate that predator-stressed crayfish release urine that causes other crayfish to move away from the source of the signal. Responses to stress chemical signals may allow receiving organisms to avoid the fate of the signal sender.

Neural crest can form cartilages normally derived from mesoderm during development of the avian head skeleton.

The lateral wall of the avian braincase, which is indicative of the primitive amniote condition, is formed from mesoderm. In contrast, mammals have replaced this portion of their head skeleton with a nonhomologous bone of neural crest origin. Features that characterize the local developmental environment may have enabled a neural crest-derived skeletal element to be integrated into a mesodermal region of the braincase during the course of evolution. The lateral wall of the braincase lies along a boundary in the head that separates neural crest from mesoderm, and also, neural crest cells migrate through this region on their way to the first visceral arch. Differences in the availability of one skeletogenic population versus the other may determine the final composition of the lateral wall of the braincase. Using the quail-chick chimeric system, this investigation tests if populations of neural crest, when augmented and expanded within populations of mesoderm, will give rise to the lateral wall of the braincase. Results demonstrate that neural crest can produce cartilages that are morphologically indistinguishable from elements normally generated by mesoderm. These findings (1) indicate that neural crest can respond to the same cues that both promote skeletogenesis and enable proper patterning in mesoderm, (2) challenge hypotheses on the nature of the boundary between neural crest and mesoderm in the head, and (3) suggest that changes in the allocation of migrating cells could have enabled a neural crest-derived skeletal element to replace a mesodermal portion of the braincase during evolution.

From head to toe: conservation of molecular signals regulating limb and craniofacial morphogenesis.

Recent evidence indicates that many molecules involved in generating and patterning the limbs also play a role during craniofacial morphogenesis. On the surface, this is an unexpected finding given that these regions of the body have separate evolutionary origins, are composed of different embryonic tissues, and are quite dissimilar in their anatomy. Results from several experiments involving Sonic hedgehog and retinoic acid point to a remarkable conservation of the signaling pathways mediated by these morphogens across multiple organ systems. Moreover, mutants such as the extra-toes and doublefoot mouse, and the talpid chicken also provide insights on common developmental processes that underlie the formation of the limbs and face. The identification of highly conserved aspects of morphogenesis is important for understanding fundamental mechanisms of development, as well as for revealing the common denominator of countless birth defects and providing new strategies for their prevention and cure.

Proprioception and neuromuscular control of the shoulder after muscle fatigue.

OBJECTIVE: To examine the effects of fatigue on proprioception and neuromuscular control of the shoulder. DESIGN AND SETTING: Subjects were randomly assigned to either an experimental group or control group. Subjects were tested using either the active angle-reproduction or the single- arm dynamic stability test. The subjects were then fatigued using a dynamometer performing continuous, concentric rotation exercises of the shoulder. Once fatigued, the subjects were posttested using the same test. One week later, the subjects returned and were pretested, fatigued, and posttested using the other test. SUBJECTS: Thirty-two college-age (18 to 25 years) subjects (16 males, 16 females) with no history of glenohumeral instability or upper extremity injury volunteered for this study. MEASUREMENTS: Absolute angular error was measured using an electrogoniometer present within the isokinetic dynamometer, while sway velocity was measured using a force-plate system. RESULTS: Repeated-measures analysis of variance revealed a significant difference between the pretest and posttest values for absolute angular error in the experimental group, whereas no significant difference was revealed between pretest and posttest sway velocity for either the control or experimental group. CONCLUSIONS: Fatigue of the internal and external rotators of the shoulder decreased proprioception of the shoulder, while having no significant effect on neuromuscular control.

Reliability and validity of the Multidimensional Fatigue Inventory (MFI-20) and the Rhoten Fatigue Scale among rural cancer outpatients.

Cancer patients typically experience fatigue while undergoing treatment for their disease. This study was an effort to identify a reliable and economical measure of fatigue. In particular, scores on the five subscales of the Multidimensional Fatigue Inventory (MFI-20) were analyzed for internal consistency and then correlated with scores on the Rhoten Fatigue Inventory to establish a measure of validity. Moderate-to-high Cronbach alphas coefficients were established for the General Fatigue subscale of the MFI-20 using a sample of 97 rural oncology outpatients (1). Partial associations with the Rhoten Fatigue Scale lend evidence to the validity of the MFI-20 measures.

Concurrent validity of the Beck Depression Inventory and the multidimensional fatigue inventory-20 in assessing fatigue among cancer patients.

Cancer patients experience both fatigue and depression while undergoing treatment for their disease. A number of authors have conceptualized such depression among this populations as secondary to fatigue. This study of 54 patients was done to test the concurrent validity of two inventories. Scores on the five subscales of the 20-item Multidimensional Fatigue Inventory were correlated with those on the 21-item Beck Depression Inventory. Moderate correlations are reported and the potential usefulness of the Multidimensional Fatigue Inventory is discussed.

Have gene knockouts caused evolutionary reversals in the mammalian first arch?

Many recent gene knockout experiments cause anatomical changes to the jaw region of mice that several investigators claim are evolutionary reversals. Here we evaluate these mutant phenotypes and the assertions of atavism. We argue that following the knockout of Hoxa-2, Dlx-2, MHox, Otx2, and RAR genes, ectopic cartilages arise as secondary consequences of disruptions in normal processes of cell specification, migration, or differentiation. These disruptions cause an excess of mesenchyme to accumulate in a region through which skeletal progenitor cells usually migrate, and at a site of condensation that is normally present in mammals but that is too small to chondrify. We find little evidence that these genes, when disrupted, cause a reversion to any primitive condition and although changes in their expression may have played a role in the evolution of the mammalian jaw, their function during morphogenesis is not sufficiently understood to confirm such hypotheses.

Expression of heat-stable enterotoxin STb by adherent Escherichia coli is not sufficient to cause severe diarrhea in neonatal pigs.

The role of Escherichia coli heat-stable enterotoxin B (STb) in neonatal porcine diarrhea caused by enterotoxigenic E. coli was examined by comparing adherent isogenic strains with or without STb. The cloned STb gene (in the plasmid pRAS1) was electroporated into a nonenterotoxigenic strain (226M) which expresses the F41 adhesin. Strain 226M pRAS1 adhered and expressed STb in vivo, causing fluid secretion in ligated ileal loops in neonatal pigs. Although strain 226M pRAS1 caused very mild diarrhea in some orally inoculated neonatal pigs, the weight loss in these pigs was similar to that caused by the parental strain without STb. We conclude that STb does not significantly contribute to diarrhea caused by enterotoxigenic E. coli in neonatal pigs.

Virulence attributes of Escherichia coli isolated from dairy heifer feces.

Escherichia coli isolates from 1,305 (of 6,894) fecal samples collected during the 1991-1992 USDA, Animal and Plant Health Inspection Service, National Health Monitoring System, Diary Heifer Evaluation Project were tested for virulence attributes associated with human enterohaemorrhagic E. coli (EHEC) and the enterotoxin commonly associated with diarrhoea in newborn calves. Single, random isolates from each heifer were hybridized to probes derived from the 60 mDa EHEC plasmid (CVD 419), E. coli attaching and effacing gene (eae), Shiga-like toxin (slt) genes I and II, and E. coli heat-stable enterotoxin a (STaP). Seventy-seven of the 1305 isolates (5.9%) were slt-positive. Most (81.8%) slt-positive E. coli were also CVD 419 and eae-positive. Only 2 of the slt-positive E. coli isolates were STaP-positive.