Search PubMed⌕ Search

Biomedical subjects

D R Brooks

Publications and source records attributed to D R Brooks.

At least 73 records · Page 4Linked to original sources

Elevated blood lead levels among construction workers in the Massachusetts Occupational Lead Registry.

Although the construction industry until recently was exempt from the Occupational Health and Safety Administration General Industry Lead Standard, including its medical monitoring provisions, periodic blood lead tests have been required for residential "deleaders" and structural painters in Massachusetts. Sixty-three percent of the 381 registrants in the Massachusetts Occupational Lead Registry with blood lead levels of 1.93 mumol/L or higher are construction workers. This proportion is much higher than that reported by registries of several states selected for comparison. These data highlight the need for better protection from lead exposure and the effectiveness of mandatory medical surveillance in identifying elevated blood lead levels among construction workers.

Adolescent↗

Escherbothrium molinae n. gen. et n. sp. (Eucestoda: Tetraphyllidea: Triloculariidae) in Urotrygon chilensis (Chondrichthyes: Myliobatiformes: Urolophidae) from the Gulf of Nicoya, Costa Rica.

Cestodes collected in spiral valves of the stingray Urotrygon chilensis from the Pacific coast of Costa Rica represent an undescribed species of Tetraphyllidea. By possessing more than 2 loculi as well as an apical sucker on each bothridium, the new species is diagnosably distinct from all other tetraphyllidean genera; therefore, a new genus is proposed for it. The new species also possesses globular structures irregularly arranged on the surface of the bothridia. We found similar structures on the bothridial faces of Trilocularia acanthiaevulgaris, possibly indicating phylogenetic relationships with the new species. This possibility is enhanced by the observation that the bothridia of T. acanthiaevulgaris comprise 2 loculi and an apical sucker, rather than 3 loculi.

Animals↗

Work-related injuries among Massachusetts children: a study based on emergency department data.

Millions of children in the United States work and, despite federal and state laws, face safety hazards. Previous studies have documented large numbers of injuries suffered on the job by working children. This study describes work-related injuries to children 14-17 years old in 14 Massachusetts communities (representing 5% of the state population) based on data from emergency departments and hospital admissions collected as part of a large population-based surveillance study of injuries to children and adolescents from 1979 to 1982. An estimated 1,176 work-related injuries occurred during the three-year period, accounting for 7-13% of all injury-related emergency department visits in this age group; the proportion among 17-year-olds was 14-26%. Cuts and lacerations were the most frequent type of injury, cutting/piercing was the most common cause, and cutting instruments were the most frequently identified products. Seventeen children were hospitalized for work-related injuries during the course of the study. The estimated annual rate of occupational injury rose from 3.7/1,000 children for 14- to 15-year-olds to 44.7/1000 for 17-year-olds; these rates count all resident children, regardless of their employment status, in the denominator. Rates based on actual hours worked are much higher, and strongly suggest that working minors should be considered a high-risk group for occupational injury. This study adds to the mounting evidence that work-related injuries to children are a significant public health problem and contribute significantly to the overall incidence of injuries among children 14-17 years old. The study also demonstrates the potential of emergency department data as a valuable source of information about work-related injuries to children. Active surveillance systems combining data from emergency departments, workers' compensation, and other potential sources should be established to fully document the nature and extent of the problem. Efforts to prevent these injuries will require the combined attention of employers, parents, medical providers, educators and regulators, as well as working children themselves.

Accidents, Occupational↗

Some Platyhelminths inhabiting white-throated sparrows, Zonotrichia albicollis (Aves: Emberizidae: Emberizinae), from Algonquin Park, Ontario, Canada.

Twenty-two of 26 white-throated sparrows, Zonotrichia albicollis, from Algonquin Park, Ontario, Canada, hosted 1 or 2 species of platyhelminths. One species of cestode and 3 of digeneans were collected. Anonchotaenia quiscali inhabited 50% of the sparrows. This is the third report of A. quiscali; Z. albicollis is a new host. Brachylecithum nanum inhabited 43%, Zonorchis alveyi 15%, and Prosthogonimus macrorchis 8% of the sparrows examined. Ontario is a new geographic distribution record from all 4 parasite species. The proportion of hosts infected with 2 species was not significantly different from expected based on single species prevalences, indicating that there is no competitive interaction among these species of parasites for access to the avian hosts.

Animals↗

Occupation, smoking, and the risk of high-grade invasive bladder cancer in Missouri.

Numerous epidemiological studies have established that occupational exposures and smoking are the two major known risk factors for the development of bladder cancer. Using data from the Missouri Cancer Registry, we investigated the hypothesis that individuals with occupationally-related bladder cancer are more likely to have a more invasive form of the disease. Data were analyzed for 2,893 white males diagnosed with primary bladder cancer in Missouri between 1984 and 1988. Of the 1,415 cases whose occupational status was recorded, 236 (17%) were employed in high-risk occupations. Cases with high-grade disease were more likely to have been employed in a high-risk occupation, after adjustment for age and smoking (adjusted odds ratio [AOR] = 1.7, 95% confidence interval [CI] = 1.1-2.6). High-risk workers under 60 years of age were most at risk for developing high-grade bladder tumors (AOR = 2.3, 95% CI = 1.0-5.3). There was no overall association between high-risk occupation and late-stage disease (AOR = 1.1, 95% CI = 0.7-1.5), but it was present in the men younger than 60 years of age (AOR = 2.0, 95% CI = 1.0-3.8). No association was found between tobacco use and grade (AOR = 1.1, 95% CI = 0.8-1.5), but cases with late-stage disease were more likely to be smokers (AOR = 1.5, 95% CI = 1.1-1.9). When occupations were examined individually, motor vehicle operators, truck drivers, vehicle mechanics, other mechanics, and janitors were among those most likely to be diagnosed with high-grade or late-stage tumors. Although further studies are necessary to confirm these results, they suggest that surveillance and targeted screening of workers in high-risk occupations may result in a greater yield of early invasive cancers and possibly decrease the mortality associated with this disease.

Aged↗

Cestode parasites in Potamotrygon motoro (Natterer) (Chondrichthyes: Potamotrygonidae) from southwestern Brazil, including Rhinebothroides mclennanae n. sp. (Tetraphyllidea: Phyllobothriidae), and a revised host-parasite checklist for helminths inhabiting neotropical freshwater stingrays.

Specimens of 5 species of cestodes were collected in 6 specimens of the freshwater stingray species Potamotrygon motoro (Natterer), collected in the vicinity of Corumba, Mato Grosso do Sul, Brazil. Acanthobothrium regoi, Potamotrygonocestus orinocoensis, Rhinebothroides venezuelensis, and Rhinebothrium paratrygoni are reported from P. motoro and from southwestern Brazil for the first time. Rhinebothroides mclennanae n. sp. appears to be the sister species of Rhinebothroides glandularis, the only other member of the genus exhibiting darkly staining glandular cells lying free in the parenchyma surrounding the terminal genitalia. The new species resembles Rhinebothroides glandularis, Rhinebothroides freitasi, and Rhinebothroides scorzai by having poral ovarian arms that extend anteriorly beyond the posterior margin of the cirrus sac, coiled vaginae, and vitelline follicles not interrupted on the poral side in the vicinity of the genital pore. It differs from all 6 previously described members of the genus by possessing an average of 31 testes per proglottid, compared with an average of 45 for R. glandularis, 55 for R. freitasi and R. venezuelensis, 77 for Rhinebothroides circularisi and Rhinebothroides moralarai, and 80 for R. scorzai. An updated phylogenetic tree for Rhinebothroides is presented.

Animals↗

Origins, diversification, and historical structure of the helminth fauna inhabiting neotropical freshwater stingrays (Potamotrygonidae).

Members of the freshwater stingray family Potamotrygonidae occur throughout the major river systems of eastern South America that empty into the Atlantic Ocean. Ichthyologists have tended to assume that the ancestor of the potamotrygonids was an Atlantic marine or euryhaline stingray that dispersed into freshwater, presumably during the last marine ingression 3-5 million years ago. The helminth parasites that inhabit potamotrygonids suggest an alternative perspective on their origin. Phylogenetic and biogeographic analysis of the helminths inhabiting potamotrygonids suggest that the hosts are derived from an ancestral Pacific urolophid stingray that was trapped in freshwater by the uplifting of the Andes beginning perhaps as early as the early Cretaceous period and ending by the mid-Miocene epoch, changing the course of the Amazon River, which previously had flowed into the Pacific Ocean.

Animals↗

Parasites and sexual selection: a macroevolutionary perspective.

The Hamilton-Zuk hypothesis postulates a causal link between parasitism and the evolution of epigamic traits by intersexual selection. Oversimplified assumptions about basic parasite biology, ambiguous formulation of the hypothesis, and poor communication between ethologists and parasitologists have hampered its testing. The hypothesis is supported at the microevolutionary level if females show significant preference for lightly or uninfected males, if intensity of infection reflects host resistance to parasites that depress host fitness by causing disease, and if intensity of infection is related to the degree of epigamic development. It must be shown that particular parasites cause disease, that the host population is polymorphic for resistance to infection by those species, and that female hosts are capable of distinguishing male hosts with low parasite loads due to heritable aspects of host resistance from males that are uninfected due to chance. The macroevolutionary prediction of the hypothesis, that species displaying strongly developed epigamic characters should host "more parasites" than species with weakly developed epigamic traits, contradicts the microevolutionary dynamic of the hypothesis, and is too ambiguous. We propose a macroevolutionary prediction based on understanding the evolutionary origin of epigamic traits and the evolutionary origin of each host-parasite association. Associations originating in the ancestor in which the epigamic trait appeared corroborate the hypothesis most strongly; those originating prior to the evolution of the epigamic trait corroborate it weakly; those beginning after the origin of the epigamic trait could not have been involved in the origin and spread of the epigamic trait.

Animals↗

Phylogenetic analysis of Alloglossidium Simer, 1929 (Digenea: Plagiorchiiformes: Macroderoididae) with discussion of the origin of truncated life cycle patterns in the genus.

Alloglossidium comprises 9 species of North American plagiorchiiform digeneans using ictalurid catfish, freshwater crustacea, and hirudinid leeches as definitive hosts. Two hypotheses about the evolution of this array of definitive hosts were examined using phylogenetic systematic analysis. Two most parsimonious trees, based on 15 homologous series derived from morphological data, each indicated the 2 species utilizing ictalurid catfish definitive hosts are basal members of the group, whereas the 2 species using freshwater crayfish definitive hosts and the 5 utilizing leech definitive hosts each comprise relatively derived monophyletic sister groups. The results suggest that species using crustaceans as definitive hosts are derived by life cycle truncation, whereas those using leeches as definitive hosts appear to be derived through a switch from crustaceans to leeches.

Animals↗

Advances in screening protocols for the detection of early bladder cancer.

Bladder cancer screening faces several obstacles, including low yield, numerous false-positive results, and the absence of a single effective screening test. We present a model of a screening program that (1) targets an occupational cohort exposed to a putative carcinogen, to increase the detection of disease, (2) uses four screening tests in parallel to maximize case detection, and (3) defines a diagnostic protocol that minimizes the number of invasive procedures by utilizing both flexible and rigid cystoscopy. In a hypothetical cohort of 1000 men aged 45 to 74 years potentially exposed to a bladder carcinogen, the model would find eight of the nine detectable cancers, with a sensitivity of 89% and a specificity of 78%. In addition, the model allows the sensitivities, specificities, and predictive values of the individual screening tests to be compared and evaluated in a single cohort.

Aged↗

The phylogeny of the cercomeria (Platyhelminthes: Rhabdocoela) and general evolutionary principles.

The unified theory of evolution is an expansion of Darwinian theory that asserts that evolution is driven by entropic accumulation of genetic information that is constrained and organized primarily by the genealogical effects of phylogenetic history and developmental integration, and secondarily by ecological effects, or natural selection in its classical mode. Phylogenetic systematic analysis of the 8 major groups of parasitic rhabdocoelous platyhelminths permits empirical macroevolutionary evaluation of these postulates. Of the 131 characters considered, 127 are phylogenetically constrained, and 4 show evidence of 1 case of convergence each. Data from different developmental stages are phylogenetically congruent, despite differences in ecology among those stages. Ecological diversification, indicated by phylogenetic association of definitive hosts and parasites, and by changes in ecological components of life cycle patterns, is more conservative evolutionarily than diversification in developmental patterns, indicated by the appearance of unique larval stages, asexual proliferation of larvae, polyembryony, and heterochronic changes. These observations support the macroevolutionary postulates of the unified theory.

Animals↗

The importance of protistan phylogeny for macroevolution.

Explicit estimates of protist phylogeny should play a key role in the development of macroevolutionary theory. Nearly half the evolutionary history of living systems involved only protists, and many trends and traits of macroevolutionary significance originated in protist groups. Special areas of research that can make use of protist phylogenies include: (1) origin of life studies, (2) biotic aspects of the evolution of the environment, (3) developmental biology and evolution, and (4) macroevolutionary trends in the diversification of life.

Animals↗

Rhinebothrium devaneyi n. sp. (Eucestoda: Tetraphyllidea) and Echinocephalus overstreeti Deardorff and Ko, 1983 (Nematoda: Gnathostomatidae) in a thorny back ray, Urogymnus asperrimus, from Enewetak Atoll, with phylogenetic analysis of both species groups.

The new species is a member of an apparently monophyletic group within the genus that includes R. flexile, R. walga, R. himanturi, R. burgeri, R. euzeti, R. hawaiiensis, R. urobatidium, R. paratrygoni, R. ditesticulum, R. tetralobatum, R. margaritense, R. biorchidum, and R. spinicephalum. All of these species have bothridia with medial longitudinal septa, a constriction at mid-bothridium, and, primitively, at least 42 loculi per bothridium and 17-22 testes per proglottid. Of the above, the new species is apparently most closely related to R. burgeri, with which it shares an increased number of testes (30-43) per proglottid, a V-shaped ovary, and a muscular genital pore. The new species is distinct by virtue of possessing 94-152 loculi per bothridium--no other known species has more than 78. This is the second report of Echinocephalus overstreeti from a stingray. It represents a new host, U. asperrimus, and a new location, Enewetak Atoll. Phylogenetic and biogeographic analysis of each species group suggests an ancient Tethys Sea-circum-Pacific origin and evolution. This supports the hypothesis of ancient Pacific origins for potamotrygonid stingrays.

Animals↗

Nonequilibrium thermodynamics and different axioms of evolution.

Proponents of two axioms of biological evolutionary theory have attempted to find justification by reference to nonequilibrium thermodynamics. One states that biological systems and their evolutionary diversification are physically improbable states and transitions, resulting from a selective process; the other asserts that there is an historically constrained inherent directionality in evolutionary dynamics, independent of natural selection, which exerts a self-organizing influence. The first, the Axiom of Improbability, is shown to be nonhistorical and thus, for a theory of change through time, acausal. Its perception of the improbability of living states is at least partially an artifact of closed system thinking. The second, the Axiom of Historically Determined Inherent Directionality, is supported evidentially and has an explicit historical component. Historically constrained dynamic populations are inherently nonequilibrium systems. It is argued that living, evolving systems, when considered to be historically constrained nonequilibrium systems, do not appear improbable at all. Thus, the two axioms are not compatible. Instead, the Axiom of Improbability is considered to result from an unjustified attempt to extend the contingent proximal actions of natural selection into the area of historical, causal explanations. It is thus denied axiomatic status, and the effects of natural selection are subsumed as an additional level of constraint in an evolutionary theory derived from the Axiom of Historically Determined Inherent Directionality.

Biological Evolution↗