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Rebecca Z. German

Bio: Rebecca Z. German is an academic researcher from Northeast Ohio Medical University. The author has contributed to research in topics: Swallowing & Tongue. The author has an hindex of 30, co-authored 114 publications receiving 2899 citations. Previous affiliations of Rebecca Z. German include Johns Hopkins University & Kennedy Krieger Institute.
Topics: Swallowing, Tongue, Dysphagia, Lesion, Medicine


Papers
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Journal ArticleDOI
TL;DR: Comparison by Western blot of FGF-2 transgenic mice to nontransgenic littermates showed expression of human F GF-2 protein in all major organs and tissues examined including brain, heart, lung, liver, kidney, spleen, and skeletal muscle; however, different molar ratios of FGRD protein isoforms were observed between different organs and tissue.
Abstract: Basic fibroblast growth factor (FGF-2) is a pleiotropic growth factor detected in many different cells and tissues. Normally synthesized at low levels, FGF-2 is elevated in various pathologies, most notably in cancer and injury repair. To investigate the effects of elevated FGF-2, the human full-length cDNA was expressed in transgenic mice under control of a phosphoglycerate kinase promoter. Overexpression of FGF-2 caused a variety of skeletal malformations including shortening and flattening of long bones and moderate macrocephaly. Comparison by Western blot of FGF-2 transgenic mice to nontransgenic littermates showed expression of human FGF-2 protein in all major organs and tissues examined including brain, heart, lung, liver, kidney, spleen, and skeletal muscle; however, different molar ratios of FGF-2 protein isoforms were observed between different organs and tissues. Some tissues preferentially synthesize larger isoforms of FGF-2 while other tissues produce predominantly smaller 18-kDa FGF-2. Translation of the high molecular weight isoforms initiates from unconventional CUG codons and translation of the 18-kDa isoform initiates from an AUG codon in the FGF-2 mRNA. Thus the Western blot data from the FGF-2 transgenic mice suggest that tissue-specific expression of FGF-2 isoforms is regulated translationally.

308 citations

Journal ArticleDOI
12 Jun 1987-Science
TL;DR: The quantitative study of directionality in life's history (replacing vague, untestable, and culturally laden notions of "progress") should receive more attention from paleobiologists.
Abstract: Evolutionary time has a characteristic direction as demonstrated by the asymmetry of clade diversity diagrams in large statistical samples. Evolutionary groups generally concentrate diversity during their early histories, producing a preponderance of bottom-heavy clades among those that arise early in the history of a larger group. This pattern holds across taxonomic levels and across differences in anatomy and ecology (marine invertebrates, terrestrial mammals). The quantitative study of directionality in life's history (replacing vague, untestable, and culturally laden notions of "progress") should receive more attention from paleobiologists.

106 citations

Journal ArticleDOI
TL;DR: This pattern of electromyographic activity in the pharyngeal swallow was reinvestigated, testing two hypotheses concerning EMG variation: 1) that it could be reduced with modern methodology and 2) thatIt could be explained by selective detection of different types of motor units.
Abstract: The currently accepted description of the pattern of electromyographic (EMG) activity in the pharyngeal swallow is that reported by Doty and Bosma in 1956; however, those authors describe high levels of intramuscle and of interindividual EMG variation. We reinvestigated this pattern, testing two hypotheses concerning EMG variation: 1) that it could be reduced with modern methodology and 2) that it could be explained by selective detection of different types of motor units. In eight decerebrate infant pigs, we elicited radiographically verified pharyngeal swallows and recorded EMG activity from a total of 16 muscles. Synchronization signals from the video-radiographic system allowed the EMG activity associated with each swallow to be aligned directly with epiglottal movement. The movements were highly stereotyped, but the recorded EMG signals were variable at both the intramuscle and interanimal level. During swallowing, some muscles subserved multiple functions and contained different task units; there we...

95 citations

Journal ArticleDOI
TL;DR: In the normalized and averaged EMG data, there were significant differences in the timing of genioglossus activity and in the relative balance of hyoglossal and stylohyoid activity.
Abstract: !"#$%!&$ The movements of the tongue, hyoid, and jaw were recorded cineradiographically in preweaning pigs as they suckled bariumized milk from a veterinary teat or drank it from a bowl. The movements were quantified by measuring the X, Y coordinates of radioopaque markers embedded in the tongue and attached to both jaws and to the hyoid. EMG activity in masseter, anterior digastric, geniohyoid, genioglossus, hyoglossus, sternohyoid, stylohyoid, and omohyoid muscles was recorded synchronously with cineradiography at 100 frames/sec. In both suckling and drinking, the movements were characterized by minimal movements of the jaw and hyoid but extensive movements of the tongue. In suckling, the movements were largely confined to the mid- posterior part of the tongue. A seal was formed between the posterior tongue and soft palate while a depression formed in the mid-tongue; this was associated with fluid moving into the depression probably because of a reduced intraoral pressure. The depression was associated with increased EMG activity in the genioglossus muscle and overlapping activity in digastric, geniohyoid, hyoglos- sus, and sternohyoid muscles. In drinking cycles, significant movement occurred in all parts of the tongue; milk ingestion was associated with tongue movements that combined elements character- istic both of suckling (mid-tongue depression with a posterior seal) and of lapping (extensive antero- posterior movements within the tongue itself). In drinking, compared to suckling, there was a major reduction in EMG activity in masseter, digastric, geniohyoid, and sternohyoid muscles. Af- ter milk had accumulated in the valleculae, swallows usually occurred in every other cycle during suckling and in every third or fourth cycle during drinking. The emptying of the valleculae was an event that was embedded in the early jaw-opening phase of an otherwise normal suckling or drinking cycle. Emptying of the valleculae was associated with posteriorly directed movement of the back of the tongue and increased EMG activity in hyoglossus, styloglossus, and omohyoid muscles. No differences were noted in the kinematics associated with swallowing in the two activi- ties, but, in the normalized and averaged EMG data, there were significant differences in the timing of genioglossus activity and in the relative balance of hyoglossal and stylohyoid activity. '( )*+(,-../(,01234 © 1998 Wiley-Liss, Inc.

91 citations

Journal ArticleDOI
TL;DR: The results suggest that functional demands of the viscerocranium were greater after birth, and that growth in this area was faster, than in the control rats, which reached functional adult proportions earlier and was therefore more susceptible to epigenetic perturbations such as dietary protein level.
Abstract: To investigate the effects of protein malnutrition on a normal growth trajectory, we radiographed Rattus norvegicus from 22 d (weaning) and continuing past adult size. We took measurements from longitudinal radiographs of rats fed a control diet and littermates fed an isocaloric low protein experimental diet. A Gompertz model was fit to each individual rat for body weight and 22 measurements of the craniofacial skeleton, producing parameters that described the rate and timing of growth. We tested for differences in these parameters due to diet, sex and litter with a mixed-model three-way ANOVA. Allometric analysis examined the scaling relationships between and within various regions of the skull. For most measurements, final sizes predicted by the model were not significantly different between rats fed the two diets, although the differences in final measurements showed small, but significant differences in growth between rats in the two diet groups. The instantaneous initial rate of growth, maximum rate of growth and deceleration of growth were significantly higher in the control rats for every measurement. Rats fed the low protein diet grew for a significantly longer period of time. The shape of the neurocranium was relatively conserved between diet groups; however, rats fed the low protein diet had shorter and relatively wider skulls than the controls. These results suggest that functional demands of the viscerocranium were greater after birth, and that growth in this area was faster. The viscerocranium reached functional adult proportions earlier and was therefore more susceptible to epigenetic perturbations such as dietary protein level. Protein malnutrition did not affect many aspects of adult size, but strongly altered the growth trajectory to achieve that size.

90 citations


Cited by
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Journal Article
TL;DR: For the next few weeks the course is going to be exploring a field that’s actually older than classical population genetics, although the approach it’ll be taking to it involves the use of population genetic machinery.
Abstract: So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

9,847 citations

Journal ArticleDOI
TL;DR: There is every reason to believe that a specialization for grammar evolved by a conventional neo-Darwinian process, as well as other arguments and data.
Abstract: Many people have argued that the evolution of the human language faculty cannot be explained by Darwinian natural selection. Chomsky and Gould have suggested that language may have evolved as the by-product of selection for other abilities or as a consequence of as-yet unknown laws of growth and form. Others have argued that a biological specialization for grammar is incompatible with every tenet of Darwinian theory – that it shows no genetic variation, could not exist in any intermediate forms, confers no selective advantage, and would require more evolutionary time and genomic space than is available. We examine these arguments and show that they depend on inaccurate assumptions about biology or language or both. Evolutionary theory offers clear criteria for when a trait should be attributed to natural selection: complex design for some function, and the absence of alternative processes capable of explaining such complexity. Human language meets these criteria: Grammar is a complex mechanism tailored to the transmission of propositional structures through a serial interface. Autonomous and arbitrary grammatical phenomena have been offered as counterexamples to the position that language is an adaptation, but this reasoning is unsound: Communication protocols depend on arbitrary conventions that are adaptive as long as they are shared. Consequently, language acquisition in the child should systematically differ from language evolution in the species, and attempts to analogize them are misleading. Reviewing other arguments and data, we conclude that there is every reason to believe that a specialization for grammar evolved by a conventional neo-Darwinian process.

2,002 citations

19 Nov 2012

1,653 citations

Journal ArticleDOI
TL;DR: A positional cloning approach was used to identify the ADHR gene which included the annotation of 37 genes within 4 Mb of genomic sequence, and missense mutations in a gene encoding a new member of the fibroblast growth factor (FGF) family, FGF23 were identified.
Abstract: Proper serum phosphate concentrations are maintained by a complex and poorly understood process. Identification of genes responsible for inherited disorders involving disturbances in phosphate homeostasis may provide insight into the pathways that regulate phosphate balance. Several hereditary disorders of isolated phosphate wasting have been described, including X-linked hypophosphataemic rickets1 (XLH), hypophosphataemic bone disease2 (HBD), hereditary hypophosphataemic rickets with hypercalciuria3 (HHRH) and autosomal dominant hypophosphataemic rickets4,5 (ADHR). Inactivating mutations of the gene PHEX, encoding a member of the neutral endopeptidase family of proteins, are responsible for XLH (refs 6,7). ADHR (MIM 193100) is characterized by low serum phosphorus concentrations, rickets, osteomalacia, lower extremity deformities, short stature, bone pain and dental abscesses4,5. Here we describe a positional cloning approach used to identify the ADHR gene which included the annotation of 37 genes within 4 Mb of genomic sequence. We identified missense mutations in a gene encoding a new member of the fibroblast growth factor (FGF) family, FGF23. These mutations in patients with ADHR represent the first mutations found in a human FGF gene.

1,429 citations

Journal Article

1,091 citations