Publications by authors named "David M Webb"

Although many studies relating stature to foot length have been carried out, the relationship between foot size and body mass remains poorly understood. Here we investigate this relationship in 193 adult and 50 juvenile habitually unshod/minimally shod individuals from five different populations-Machiguenga, Daasanach, Pumé, Hadzabe, and Samoans-varying greatly in body size and shape. Body mass is highly correlated with foot size, and can be predicted from foot area (maximum length × breadth) in the combined sample with an average error of about 10%.

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Objective: Intrathecal drug delivery systems (IT-DDSs) have gained more widespread use in patients with non-cancer-related pain, notably failed back surgery syndrome and spinal arachnoiditis. Secondary to the longer life spans of these patients, more complications have been discovered with IT-DDSs. With an estimated incidence of 1% to 3%, an uncommon but serious complication is that of granuloma formation.

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Background: Patients with type 1 diabetes require intensive insulin therapy for optimal glycemic control. AIR((R)) inhaled insulin (system from Eli Lilly and Company, Indianapolis, IN) (AIR is a registered trademark of Alkermes, Inc., Cambridge, MA) may be an efficacious and safe alternative to subcutaneously injected (SC) mealtime insulin.

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Background: Long-term safety and efficacy of AIR((R)) inhaled insulin (Eli Lilly and Co., Indianapolis, IN) (AIR is a registered trademark of Alkermes, Inc., Cambridge, MA) in patients with diabetes and concomitant lung disease remain to be established.

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Background: Patients with type 1 diabetes may prefer features of AIR inhaled insulin (developed by Alkermes, Inc. [Cambridge, MA] and Eli Lilly and Company [Indianapolis, IN]; AIR is a registered trademark of Alkermes, Inc.) over insulin injection, but the two methods need to be compared for efficacy and safety.

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Using data from NHANES III, we evaluated the effect of diabetes on the age-related decline in lung function. The Diabetes group (n=471) had significantly lower mean FEV(1) and FVC values than the No Diabetes group (n=4317), but pulmonary function declined with increasing age at a similar rate for both groups.

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Proteins involved in sperm-egg binding have been shown to evolve rapidly in several groups of invertebrates and vertebrates. Mammalian SED1 (secreted protein containing N-terminal Notch-like type II epidermal growth factor (EGF) repeats and C-terminal discoidin/F5/8 C domains) is a recently identified sperm surface protein that binds the egg zona pellucida and facilitates sperm-egg adhesion. SED1-null male mice are subfertile.

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Catsper1 is a voltage-gated calcium channel located in the plasma membrane of the sperm tail and is necessary for sperm motility and fertility in mice. We here examine the evolutionary pattern of Catsper1 from nine species of the rodent subfamily Murinae of family Muridae. We show that the rate of insertion/deletion (indel) substitutions in exon 1 of the gene is 4-15 times that in introns or neutral genomic regions, suggesting the presence of strong positive selection that promotes fixations of indel mutations in exon 1.

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Although the woodpeckers have long been recognized as a natural, monophyletic taxon, morphological analyses of their intra- and intergeneric relationships have produced conflicting results. To clarify this issue, and as part of a larger study of piciform relationships, nucleotide sequences for the 12S ribosomal RNA (12S; 1123 bp), cytochrome b (Cyt b; 1022 bp), and cytochrome oxidase c subunit 1 (COI; 1512 bp) mitochondrial genes were obtained from 34 piciform species that included 16 of the 23 currently recognized woodpecker genera (subfamily Picinae), three piculets (subfamily Picumninae), a wryneck (subfamily Jynginae), a honeyguide (family Indicatoridae), and three barbets (infraorder Ramphastides). Analyses were conducted on the individual and combined 12S, Cyt b, and COI sequences with maximum parsimony, neighbor-joining, maximum likelihood, and Bayesian algorithms.

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Human cytidine deaminase APOBEC3G and the virion infectivity factor (vif) of the human immunodeficiency virus (HIV) are a pair of antagonistic molecules. In the absence of vif, APOBEC3G induces a high rate of dC to dU mutations in the nascent reverse transcripts of HIV that leads to the degradation of the HIV genome. HIV vif, on the other hand, can suppress the translation and trigger the degradation of human APOBEC3G.

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Vertebrate pheromones are water-soluble chemicals perceived mainly by the vomeronasal organ (VNO) for intraspecific communications. Humans, apes, and Old World (OW) monkeys lack functional genes responsible for the pheromone signal transduction and are generally insensitive to vomeronasal pheromones. It has been hypothesized that the evolutionary deterioration of pheromone sensitivity occurred because pheromone communication became redundant after the emergence of full trichromatic color vision via the duplication of the X-chromosome-linked red/green opsin gene in the common ancestor of hominoids and OW monkeys.

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Pheromones are water-soluble chemicals released and sensed by individuals of the same species to elicit social and reproductive behaviors or physiological changes; they are perceived primarily by the vomeronasal organ (VNO) in terrestrial vertebrates. Humans and some related primates possess only vestigial VNOs and have no or significantly reduced ability to detect pheromones, a phenomenon not well understood at the molecular level. Here we show that genes encoding the TRP2 ion channel and V1R pheromone receptors, two components of the vomeronasal pheromone signal transduction pathway, have been impaired and removed from functional constraints since shortly before the separation of hominoids and Old World monkeys approximately 23 million years ago, and that the random inactivation of pheromone receptor genes is an ongoing process even in present-day humans.

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Genes responsible for human-specific phenotypes may have been under altered selective pressures in human evolution and thus exhibit changes in substitution rate and pattern at the protein sequence level. Using comparative analysis of human, chimpanzee, and mouse protein sequences, we identified two genes (PRM2 and FOXP2) with significantly enhanced evolutionary rates in the hominid lineage. PRM2 is a histone-like protein essential to spermatogenesis and was previously reported to be a likely target of sexual selection in humans and chimpanzees.

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Data on footprints and gait of 54 Hadzabe, 6-70 years of age expand understanding of pedal morphology of unshod people and assist the development of ideas about the evolution of hominid bipedality and upright posture. Contrary to published data on gaits and pedal morphology of unshod populations, Hadzabe (also known as Hadza) from northern Tanzania exhibit values of stride length, relative stride length, and walking speeds that exceed those of rural and small-town populations. In all observable plantar features, including foot indices, an interdigital space between the hallux and second toe, fanning of the foot anteriorly, and foot angles (in-toeing and out-toeing), Hadzabe feet are comparable with those of never-shod Machiguengas in Perú.

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