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Dive into the research topics where Richard A. Heckmann is active.

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Featured researches published by Richard A. Heckmann.


American Journal of Sports Medicine | 1991

Influence of local steroid injections on traumatized tendon properties. A biomechanical and histological study.

J. Wesley McWhorter; Rulon S. Francis; Richard A. Heckmann

We investigated the effects of peritendon injections of hydrocortisone acetate on the separation force required to completely avulse a posttraumatized Achilles tendon of the adult male rat. One hundred thirty-five rats were randomly assigned to 3 groups and subsequently trau matized, treated, and sacrificed. One group was used to examine the effect of trauma; the second to examine effects of trauma and injections of hydrocortisone ace tate on the tension to failure strength of tendons; the third group was the control group. Injected animals received one, three, or five injections of 0.10 cc (125 mg/ml) hydrocortisone acetate and were sacrificed 3, 6, or 9 weeks following initial injection. Experimental animals (anesthetized) were traumatized by dropping a weight onto the Achilles tendon. The tendon was tested in tension to failure employing a soft tissue linear dis seminator. Histologic analysis using light microscopy was performed. We concluded that hydrocortisone ace tate has no deleterious effect on the rat Achilles tendon as measured biomechanically or histologically.


Mutation Research-genetic Toxicology and Environmental Mutagenesis | 1999

A comparative evaluation of aflatoxin B1 genotoxicity in fish models using the Comet assay

Gamal A. Abd-Allah; Refaat I. El-Fayoumi; Micah J. Smith; Richard A. Heckmann; Kim L. O'Neill

Aflatoxin B1 (AFB1) is classified as a Group I hepatocarcinogen in humans by the International Agency for Research on Cancer (IARC). The alkaline Comet assay is a simple and rapid method by which DNA damage can be demonstrated as a function of tail moment. The present work is the first to evaluate the genotoxicity of AFB1 in fish using the Comet assay. Two different species of fish were selected as models due to previously established sensitivity to AFB1: rainbow trout (sensitive) and channel catfish (resistant). Fish were i.p. injected with 0.5 mg AFB1/1 ml DMSO/1 kg body weight. The Comet assay was performed after 4 and 24 h on whole blood, liver, and kidney cells of both species. Trout blood and kidney tissue tested displayed significant (p < 0.05) and extensive DNA damage (shown by increased tail moment) after 4 h which then decreased by 24 h. In liver cells, damage progressively increased over time. Conversely, similarly treated catfish showed no elevation in DNA damage over controls at the same doses. These results suggest that the Comet assay is a useful tool for monitoring the genotoxicity of mycotoxins such as AFB1 and for evaluating organ specific effects of these agents in different species.


Endocrine | 2000

Stimulation by Interleukin-6 and Inhibition by Tumor Necrosis Factor of Cortisol Release from Bovine Adrenal Zona Fasciculata Cells Through Their Receptors

Michelle Barney; Gerald B. Call; Christopher J. McIlmoil; Omar F. Husein; Andrew Adams; Adam G. Balls; Gustavo K. Oliveira; Edward C. Miner; Todd A. Richards; Brenda K. Crawford; Richard A. Heckmann; John D. Bell; Allan M. Judd

Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) are synthesized and released from adrenal cells. Therefore, the effects of TNF-α and IL-6 on cortisol release from bovine zona fasciculata (ZF) cells were investigated. IL-6 (10–1000 pg/mL) significantly increased basal and adrenocorticotropic hormone (ACTH)-stimulated cortisol release in a concentration-dependent manner. This stimulatory effect of IL-6 became apparent at intervals as short as 4 h and continued through 24 h. IL-6 also potentiated the cortisol release stimulated by the adenylyl cyclase activator forskolin. By contrast, TNF-α (0.1–10 ng) inhibited basal and ACTH-stimulated cortisol release in a concentration-dependent manner. The inhibitory effects of TNF-α on cortisol release were significant at time intervals as short as 4 h and continued through 24 h. TNF-α inhibited forskolin-stimulated cortisol release. Binding studies demonstrated that ZF cells have IL-6 receptors (100 receptors/cell, Kd of 7.5×10−11) and TNF receptors (200 receptors/cell, Kd of 2.4×10−9M). Immunohistochemical analysis provided evidence that the majority of ZF cells have IL-6 receptors, TNF type 1 receptors, and TNF type 2 receptors. Because IL-6 and TNF-α are released from the adrenal cortex and these cytokines modify the release of cortisol from the ZF, IL-6 and TNF-α may play a paracrine or autocrine role in the regulation of adrenal function.


Life Sciences | 1973

The life history of Sanguinicola klamathensis

Wallace A. Evans; Richard A. Heckmann

Abstract The life history of the trematode blood fluke, Sanguinicola klamathensis was studied using experimentally infected cutthroat trout ( Salmo clarki ) and by examining wild salmonid populations. This study was carried out at the Hagerman National Fish Hatchery, Idaho, during 1971–1973. Ova, miracidia, sporocysts, cercariae, immature flukes, and adult flukes were measured, described, and photographed. A life cycle for the blood fluke is presented.


Journal of Parasitology | 1987

New host records for the Asian fish tapeworm, Bothriocephalus acheilognathi, in endangered fish species from the Virgin River, Utah, Nevada, and Arizona.

Richard A. Heckmann; Paul D. Greger; James E. Deacon

Bothriocephalus acheilognathi has been considered one of the most dangerous pseudophyllidean cestodes for cultured carp in Europe. This species, first described from fish in Japan, is common in the intestine of young grass carp cultured in South China. From China, cestode infections have followed grass carp imports into Europe, Russia, and the United States (Hoffman and Schubert, 1984, In Distribution, biology, and management of exotic fishes, Courtnay and Stauffer (eds.), Johns Hopkins University Press, Baltimore, pp. 233-261). To date there have been no published records of B. acheilognathi in the fishes found in the Virgin River of Utah, Nevada, and Arizona. During a preliminary survey of parasites of Plagopterus argentissimus and other endangered fish species from the Virgin River near St. George, Utah, 18% of 17 Gila robusta seminuda examined were found to be infected with the B. acheilognathi. From the same site no P. argentissimus (192) (number checked for parasites in paren-


Journal of Parasitology | 2008

New and already known acanthocephalans from amphibians and reptiles in Vietnam, with keys to species of Pseudoacanthocephalus petrochenko, 1956 (Echinorhynchidae) and Sphaerechinorhynchus johnston and deland, 1929 (Plagiorhynchidae)

Omar M. Amin; Ngyuen Van Ha; Richard A. Heckmann

Adults of 2 new species in 2 orders of acanthocephalans obtained from the intestines of terrestrial amphibians and reptiles collected between 1998 and 2004 in Vietnam are described here. Pseudoacanthocephalus nguyenthileae n. sp. (Palaeacnthocephala: Echinorhynchidae) was collected from 5 species of terrestrial amphibians: (1) the common Sunda toad Bufo melanostictus Schneider (Bufonidae); (2) Paa verucospinosa (Bourret); (3) Gunthers Amoy frog Rana guentheri Boulenger; (4) Taipei frog R. taipehensis Denburgh (Ranidae), and (5) the Burmese whipping frog Polypedates mutus (Smith) (Racophoridae); as well as from the Chinese cobra Naja atra Cantor (Reptilia: Elapidae) and house gecko Hemidactylus frenatus Dumeril and Bibron (Reptilia: Gekkonidae). Sphaerechinorhynchus maximesospinus n. sp. (Plagiorhynchidae: Sphaerechinorhynchinae) was isolated from a king cobra Ophiophagus hannah (cantor) (Reptilia: Elapidae). Cystacanths of Porrorchis houdemeri (Joyeux and Baer, 1935) Schmidt and Kuntz, 1967 (Plagiorhynchidae: Porrorchinae) obtained from the mesenteries of banded krait Bungarus fasciatus (Schneider) (Reptilia: Elapidae), a paratenic host, are reported for the first time. Keys to the species of Pseudoacanthocephalus and Sphaerechinorhynchus are included. Characteristic features distinguishing the new species from related taxa include: P. nguyenthileae has 15–19 (usually 16–18) proboscis hook rows, each with 5–6 hooks that progressively increase in length and size posteriorly. The largest, intermediate, and smallest proboscis hooks of S. maximesospinus are the middle, anterior, and posterior hooks, respectively; the proboscis and neck are enclosed in a membrane. Morphometric characteristics of P. nguyenthileae show host-related variability.


Acta Parasitologica | 2011

Description of two new species of Rhadinorhynchus (Acanthocephala, Rhadinorhynchidae) from marine fish in Halong Bay, Vietnam, with a key to species

Omar M. Amin; Richard A. Heckmann; Nguyen Van Ha

Two rhadinorhynchid species of acanthocephalans, Rhadinorhynchus dorsoventrospinosus sp. nov. and Rhadinorhynchus laterospinosus sp. nov. are described from the redtail scad, Decapterus kurroides Bleeker, and the trigger fish Balistes sp., respectively. The hosts were collected off Cat Ba Island, Halong Bay, Gulf of Tonkin, Vietnam in May, 2009. This brings the total number of species of Rhadinorhynchus Lühe, 1911 to 38. Specimens of the first species are characterized by having 11–12 proboscis hook rows with 30–31 hooks each, large dorsal and ventral spines in the posterior field of trunk spines, large eggs (100 × 20), and subterminal gonopore in both males and females. It is further characterized by many prominent fragmented nuclei in the body wall. The 1 female of the second species has 18 proboscis hook rows with 24 hooks each, smaller eggs (62 × 17), lateral trunk spines connecting those in the anterior and the posterior fields, and subterminal female gonopore. Notes on the genus Rhadinorhynchus, lists of the invalid and valid species, and a key to species are provided. Raorhynchus Tripathi, 1959 is proposed to be a junior synonym of Rhadinorhynchus pending a revision of the species of Raorhynchus.


Journal of Parasitology | 2009

Redescription of Rhadinorhynchus ornatus (Acanthocephala: Rhadinorhynchidae) from Skipjack Tuna, Katsuwonus pelamis, Collected in the Pacific Ocean off South America, with Special Reference to New Morphological Features

Omar M. Amin; Richard A. Heckmann; Nahla A. Radwan; Johan S. Mantuano Anchundia; Marcos A. Zambrano Alcivar

Abstract Adults of Rhadinorhynchus ornatus Van Cleave, 1918 were collected from the small intestine of skipjack tuna, Katsuwonus pelamis (Linnaeus), in the high seas of the Pacific Ocean off the west coast of South America (new parasite locality record) and described using optical microscopy and a scanning electron microscope (SEM). Our specimens were somewhat comparable to those described from North America and Japan, but had more trunk spines. Definitive differences between the length and thickness of each of the dorsal and ventral proboscis hooks are noted for the first time, with most ventral middle hooks being relatively shorter and more robust than dorsal middle hooks. The SEM documented, for the first time, the different surface topography of the tegument in the proboscis, the neck, and in 3 trunk regions; the presence of microtrichs in the mid- and posterior trunk regions; the elevated base of trunk spines; the circular arrangement of basal proboscis hooks; the different morphology of all dorsal and ventral proboscis hooks and the striations of their surface; the ribbed surface topography of eggs; the elevated slit-like female gonopore; and the rimmed edge of the bursa. The presence of microtrichs on the tegumental surface is further supported by transmission electron microscopy studies. This is the first report of microtrichs in any species of Acanthocephala and the second report of striations in proboscis hooks. The geographical distribution of R. ornatus appears to correspond, at least in part, to that of its epipelagic primary host, K. pelamis, throughout the world in waters ranging in temperature from 14.7 to 30 C.


Journal of Parasitology | 1992

Description and pathology of Neoechinorhynchus idahoensis n. sp. (Acanthocephala : Neoechinorhynchidae) in Catostomus columbianus from Idaho

Omar M. Amin; Richard A. Heckmann

Neoechinorhynchus idahoensis is described from Catostomus columbianus caught in the Salmon River, Stanley Basin, Idaho. The new species is closest to Neoechinorhynchus venustus Lynch, 1936, but is distinguished from it by its smaller and variably structured eggs, anterio-dorsal trunk hump, bent and posteriorly notched proboscis receptacle, and larger proboscis, proboscis receptacle, and hooks. It is distinguished also from 2 other species of Neoechinorhynchus with proboscis hooks in middle and anterior circles about equally large and from 7 other species having lemnisci greatly unequal in length. Histopathology of host tissue showed limited host response exemplified by epithelial damage and hemorrhaging at point of proboscis attachment with subsequent macrophage and other phagocytic cell migration. The proboscis extended through the host epithelium into the submucosa with limited hemorrhaging at the point of attachment. Unorganized collagenous fibers were present. The lumen of the host intestine was obstructed, and compressed villi were present. The trunk of the worm damaged intestinal epithelium near the crypts, causing localized inflammation. The caryophyllaeid cestode Isoglaridacris calentinei Mackiewicz, 1974, was present in concurrent infections of C. columbianus.


Journal of Parasitology | 2008

New and Already Known Acanthocephalans Mostly from Mammals in Vietnam, with Descriptions of Two New Genera and Species in Archiacanthocephala

Omar M. Amin; Ngyuen Van Ha; Richard A. Heckmann

Adults of 2 new species and 2 new genera of acanthocephalans in class Archiacanthocephala, collected between 1998 and 2004 in Vietnam from the intestines of mammals, are described, i.e., Cucullanorhynchus constrictruncatus n. gen., n. sp. (Oligacanthorhynchidae) from a leopard Panthera pardus (Linnaeus) (Mammalia: Felidae) and Paraprosthenorchis ornatus n. gen. n. sp. (Oligacanthorhynchidae) from the Chinese pangolin Manis pentadactyla (Linnaeus) (Mammalia: Manidae). Adult Sphaerechinorhynchus macropisthospinus Amin, Wongsawad, Marayong, Saehoong, Suwattanacoupt, and Sey, 1998 (Plagiorhynchidae) are described for the first time from 2 females collected from a tiger Panthera tigris (Linnaeus) (Mammalia: Felidae) and from 1 male from a water monitor Varanus salvator Laurenti (Reptilia: Varanidae). Characteristic features distinguishing the new species or genera from related taxa are as follows. The trunk of C. constrictruncatus has an anterior hood in both sexes and a posterior constriction in females. The anterior trunk of P. ornatus has many small festoons and proboscis hooks are inserted in elevated papillae separated by beady, near hexagonal, ornate grids.

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Omar M. Amin

University of Wisconsin–Parkside

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Nguyen Van Ha

Vietnam Academy of Science and Technology

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Allan M. Judd

Brigham Young University

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