Studies on gut ultrastructure and digestive physiology in Rhabdias bufonis and R. sphaerocephala (Nematoda: Rhabditida)

Parasitology ◽  
1971 ◽  
Vol 62 (2) ◽  
pp. 247-258 ◽  
Author(s):  
J. Barry Colam
Keyword(s):  
Acid Phosphatase ◽  
United States Public Health ◽  
Buccal Capsule ◽  
The United States ◽  
Parasitic Nematodes ◽  
Digestive Physiology ◽  
Light Microscope Level ◽  
Inactive Form ◽  
Contact Digestion ◽  
Lung Capillaries

Histological, histochemical and ultrastructural methods have been used to study gut structure and digestive physiology in the parasitic nematodes Rhabdias bufonis (Schrank, 1788) and R. sphaerocephala (Goodey, 1924). Both species are parasitic in the lungs of their amphibian hosts and feed entirely upon blood drawn from the lung capillaries.Three gland cells are present in the oesophagus, one in each sector. The two subventral ducts open, by way of ampullae, into the lumen of the oesophagus about a quarter of its length from the anterior end. The dorsal gland opens similarly into the base of the buccal capsule. It is suggested that the glands produce a B-esterase, in an histochemically inactive form in situ, which is responsible for haemolysis and the bulk of extracellular digestion. Only one cell type is present in the intestine and this is entirely absorptive in function.The major part of haemoglobin digestion is extracellular, partly by a process of contact digestion involving the B-esterase and acid phosphatase which are present in association with the microvilli. Haematin results from this process and is precipitated in the gut lumen. A smaller proportion of haemoglobin is taken up by the gut cells and is broken down intracellularly by lysosomes, originating in Golgi in the basal gastrodermis. These show endopeptidase activity and later acid phosphatase in some of the bodies of the lysosomal sequence and only at the light microscope level. The iron-containing pigment haemosiderin resulting from digestion is retained in the lysosome residues and forms the pigment granules in the gastrodermis. The products of extracellular digestion absorbed by the gastrodermis are synthetized into lipid by a lipase, probably produced by GER.This investigation was supported in part by Research Grant AI 06295 of the United States Public Health Service. The final manuscript was prepared during the tenure of a Postdoctoral Fellowship from the British Egg Marketing Board. I wish to extend my gratitude to Dr J. B. Jennings for advice and encouragement throughout this work.

Studies on gut ultrastructure and digestive physiology in Cyathostoma lari (Nematoda: Strongylida)

Parasitology ◽  
1971 ◽  
Vol 62 (2) ◽  
pp. 273-283 ◽  
Author(s):  
J. Barry Colam
Keyword(s):  
Acid Phosphatase ◽  
United States Public Health ◽  
Buccal Capsule ◽  
The United States ◽  
Digestive Physiology ◽  
Lysosomal Hydrolases ◽  
Prosthetic Group ◽  
Distal Surface ◽  
Group A ◽  
Contact Digestion

Histological, histochemical and ultrastructural methods have been used to study the gut structure and digestive physiology in the parasitic nematode Cyathostomalari E. Banchard, 1849. The nematode is parasitic in the orbito-nasal sinuses of its host and feeds exclusively upon blood.Three gland cells are present in the oesophagus, one in each sector. The two subventral gland ducts open into the lumen of the oesophagus at the level of the nerve ring, and the dorsal gland duct into the base of the buccal capsule. It is suggested that the latter gland may produce an anticoagulin, histolytic and/or haemolytic secretions, histochemically-inactive in situ. The intestine is syncytial, with no differentiation into secretory components, and its distal surface is provided with a prominent brush border of long microvilli.A non-specific esterase, thought to originate in the oesophageal gland secretions, causes haemolysis of ingested erythrocytes. The major part of haemoglobin digestion is extracellular, partly by a process of contact digestion on the microvilli, initiated by the esterase, and the protein is then further broken down by an exopeptidase of the ‘leucine aminopeptidase’ type, and the products absorbed into the gastrodermis possibly with the aid of an acid phosphatase present on or in the microvilli. An insoluble iron-containing compound, which is not haematin, results from breakdown of the prosthetic group. A smaller proportion of haemoglobin is taken up by the gastrodermis and digested intracellularly by the action of lysosomal hydrolases. An endopeptidase and an acid phosphatase are present in the gastrodermis, possibly in sacs of GER which are suggested to be primary lysosomes and which fuse with the endocytosed heterophagosomes. The insoluble pigment haematin results from digestion within the heterolysosomes, and this gives rise to the iron-containing gastrodermal pigment granules. The products of extracellular digestion are absorbed by the gastrodermis where they are synthetized into lipid by a lipase, which probably resides in whorls of GER.This investigation was supported in part by Research Grant AI 06295 of the United States Public Health Service. The final manuscript was prepared during the tenure of a Postdoctoral Fellowship from the British Egg Marketing Board. I wish to extend my gratitude to Dr J. B. Jennings for advice and encouragement throughout this work.

Studies on gut ultrastructure and digestive physiology in Cosmocerca ornata (Nematoda: Ascaridida)

Parasitology ◽  
1971 ◽  
Vol 62 (2) ◽  
pp. 259-272 ◽  
Author(s):  
J. Barry Colam
Keyword(s):  
Extracellular Enzymes ◽  
Rana Temporaria ◽  
United States Public Health ◽  
Buccal Capsule ◽  
The United States ◽  
Gut Contents ◽  
Digestive Physiology ◽  
Cellular Debris ◽  
Oesophageal Bulb ◽  
Cosmocerca Ornata

Histological, histochemical and ultrastructural methods have been used to study gut structure and digestive physiology in Cosmocerca ornata (Dujardin, 1845). The nematode is parasitic in the small intestine and rectum of Rana temporaria, and feeds solely upon the gut contents of the host, primarily bacteria and cellular debris rather than fluid material.Only a small buccal capsule is present and no host tissue is ingested. Rigid channels at the tips of the oesophageal radii and a spiral arrangement of the corpus lumen are probably concerned in expressing any fluid in the food while retaining the particulate matter. The latter is then shredded by three large valvular flaps projecting into the lumen of the posterior oesophageal bulb. One gland is present in each sector of the bulb. There is some evidence that two secretions are produced in each subventral sector, an electron-dense one posteriorly which is released into the lumen below the valve flaps, and an electron-lucid one synthesized more anteriorly which is released in the anterior region of the bulb. Only one secretion is produced in the dorsal gland, similar to that in the anterior subventral sector, and which is poured into the lumen of the posterior corpus. The intestine is not differentiated into distinct regions and contains no gland cells. A prominent striated border of microvilli is present, varying from 25 μm in the foregut to 0·5 μm in the hindgut. They have a prominent core composed of minute fibrils and an outer glycocalyx covering.Digestion is entirely extracellular, bacteria and cellular debris in the ingesta being broken down by a C-esterase present in the oesophageal gland secretions. It is completed by a process of contact digestion with the same enzyme adsorbed on to the glycocalyx. Acid phosphatase, also produced by the oesophageal glands and present on the microvilli, may be concerned in the absorption of the resultant digestion products and any simple solutes in the food made available by host extracellular enzymes. GER and free ribosomes present in the distal regions of the gastrodermis are probably concerned in the assimilation of the absorbed materials into glycogen which is stored in large quantities in the gastrodermis.This investigation was supported in part by Research Grant AI 06295 of the United States Public Health Service. The final manuscript was prepared during the tenure of a Postdoctoral Fellowship from the British Egg Marketing Board.

scholarly journals Users’ Beliefs Toward Physical Distancing in Facebook Pages of Public Health Authorities During COVID-19 Pandemic in Early 2020

2021 ◽  
pp. 109019812110144
Author(s):  
Soon Guan Tan ◽  
Aravind Sesagiri Raamkumar ◽  
Hwee Lin Wee
Keyword(s):  
Public Health ◽  
Health Belief Model ◽  
United States Public Health ◽  
Health Belief ◽  
The United States ◽  
Health Authorities ◽  
Public Health Authorities ◽  
Control And Prevention ◽  
Belief Model ◽  
The Health Belief Model

This study aims to describe Facebook users’ beliefs toward physical distancing measures implemented during the Coronavirus disease (COVID-19) pandemic using the key constructs of the health belief model. A combination of rule-based filtering and manual classification methods was used to classify user comments on COVID-19 Facebook posts of three public health authorities: Centers for Disease Control and Prevention of the United States, Public Health England, and Ministry of Health, Singapore. A total of 104,304 comments were analyzed for posts published between 1 January, 2020, and 31 March, 2020, along with COVID-19 cases and deaths count data from the three countries. Findings indicate that the perceived benefits of physical distancing measures ( n = 3,463; 3.3%) was three times higher than perceived barriers ( n = 1,062; 1.0%). Perceived susceptibility to COVID-19 ( n = 2,934; 2.8%) was higher compared with perceived severity ( n = 2,081; 2.0%). Although susceptibility aspects of physical distancing were discussed more often at the start of the year, mentions on the benefits of intervention emerged stronger toward the end of the analysis period, highlighting the shift in beliefs. The health belief model is useful for understanding Facebook users’ beliefs at a basic level, and it provides a scope for further improvement.

PUBLIC HEALTH

PEDIATRICS ◽  
1960 ◽  
Vol 25 (2) ◽  
pp. 343-347
Author(s):  
George M. Wheatley ◽  
Stephen A. Richardson
Keyword(s):  
Public Health ◽  
United States ◽  
Cause Of Death ◽  
United States Public Health ◽  
The United States ◽  
Vital Statistics ◽  
West Germany ◽  
Medical Attention ◽  
Age Group ◽  
Number Of Children

IN ALL COUNTRIES for which there are vital statistics, accidents are a major cause of death and disability among children. In countries where the food supply is adequate and infectious diseases have been brought under control, accidents have become the leading cause of death in the age group 1 to 19 years. For example, in such countries as Australia, Canada, Sweden, West Germany, and the United States, more than one-third of all deaths in this age group are caused by accidents. The number of children who are injured by accidents fan exceeds the number who are killed. Although no accurate international figures are available, the Morbidity Survey conducted by the United States Public Health Service indicates that in the United States, for every child under 15 killed by accident, 1,100 children are injured severely enough to require medical attention or to be restricted in their activity for at least a day.

Commissioned Corps Deployments & Family Resiliency

2020 ◽  
Vol 25 (1) ◽  
Author(s):  
Janice Arceneaux ◽  
James Dickens ◽  
Wanza Bacon
Keyword(s):  
Public Health ◽  
Health And Safety ◽  
United States Public Health ◽  
Disease Outbreaks ◽  
The United States ◽  
Humanitarian Assistance ◽  
Family Resiliency ◽  
Public Health Emergencies ◽  
National Public Health ◽  
The U.S

Established in 1889, the United States Public Health Service Commissioned Corps (Corps) is one of the seven uniformed services and is part of the U.S. Department of Health and Human Services. The Corps is committed to protecting, promoting and advancing the health and safety of the nation with a history that dates back over two centuries, beginning as the U.S. Marine Hospital Service. Today, the Corps responds and serves in many areas impacted by natural disasters, disease outbreaks, terrorist attacks and public health emergencies. Corps officers have deployed to provide assistance during national public health emergencies (e.g., hurricanes, bombings, flooding and wild fires); to combat the Ebola epidemic in West Africa; and to provide humanitarian assistance in Latin America and the Caribbean. Corps deployments impact not only service members but also their families. This article offers a brief overview of the Corps and discusses how deployments impact families. Family resiliency and future implications for research and practice will also be examined.

scholarly journals First Report of the Spiral Nematode Scutellonema brachyurum on Lilyturf in the United States

Plant Disease ◽  
2011 ◽  
Vol 95 (1) ◽  
pp. 74-74 ◽  
Author(s):  
P. Agudelo ◽  
D. Harshman
Keyword(s):  
United States ◽  
Population Density ◽  
The United States ◽  
Parasitic Nematodes ◽  
Initial Population ◽  
Herbaceous Plant ◽  
Plant Parasitic Nematodes ◽  
Essential Information ◽  
First Report ◽  
Plant Parasitic

Lilyturf (Liriope muscari (Decne.) L.H. Bailey), an herbaceous plant, is commonly used in landscaping including borders (along sidewalks, driveways, and trees) and mass plantings as groundcover in the southeastern United States. In December of 2009, a soil sample was submitted to our lab for diagnosis of plant-parasitic nematodes from an area planted with lilyturf located on the Clemson University main campus. A high population density (1,220 individuals/100 cm3 of soil) of spiral nematodes (Scutellonema brachyurum (Steiner, 1938) Andrássy, 1958) was found by routine extraction by sugar centrifugal flotation (3). Other plant-parasitic nematodes, mainly ring nematodes (10 individuals/100 cm3) and stubby root nematodes (10 individuals/100 cm3), were present. To verify if high numbers of spiral nematodes were consistently associated with lilyturf, 20 additional soil and root samples were collected from different places on the campus. In all cases, S. brachyurum was found in densities ranging from 680 to 1,600 individuals/100 cm3 of soil (average of 1,210 individuals/100 cm3). The species was identified by morphological characters of females, including well developed stylet (26 to 30 μm long), no spermatheca, no sperm in uterus, tail broadly rounded with 8 to 12 annules between anus and tail, and scutella at anus level. As is commonly the case for this species, no males were found in any of the samples collected. Examination of the roots revealed numerous, small, reddish brown, necrotic lesions, apparently caused by the feeding and penetration of S. brachyurum. Host plant suitability and pathogenicity of the nematode were tested in the greenhouse. Ten nematode-free lilyturf plants grown individually in 15-cm-diameter plastic pots with pasteurized soil were inoculated with 1,000 spiral nematodes each. Ten uninoculated plants were kept under identical conditions as controls. Three months after inoculation, soil population densities were measured and reproduction factors were calculated to be between 2.8 and 5.4 (final population density divided by initial population density) for the 10 plants. Characteristic lesions previously described were observed in the roots of all inoculated plants, along with slight chlorosis of foliage. These symptoms were not observed on control plants. Spiral nematodes may attack the roots and stolons of lilyturf as ectoparasites or they may enter them and feed in the cortex as endoparasites. Although root lesions were common on affected plants, root injury in general was not severe and generalized root decay was not observed on either the collected plants or those from the greenhouse study. Reports on the pathogenicity of S. brachyurum are variable. Moderate damage was recorded on amaryllis and other ornamentals (4), while measurable damage was observed on tobacco (2), with approximately 100 individuals/100 cm3 of soil, and severe damage on Aloe vera ((L.) Burm. f.), with approximately 500 individuals/100 cm3 (1). To our knowledge, this is the first report of S. brachyurum causing visible symptoms on lilyturf. As the interstate and international movement of perennial plants continues to grow, awareness of the host status of potentially harmful nematodes becomes essential information. References: (1) R. P. Esser et al. Nematropica 16:65, 1986. (2) T. W. Graham. Phytopathology (Abstr.) 45:347, 1955. (3) W. R. Jenkins. Plant Dis. Rep. 48:692, 1964. (4) L. Nong and G. F. Weber. (Abstr.) Phytopathology 54:902, 1964.

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