The factors instrumental in triggering latent tuberculosis (TB) infection to progress into active disease have long remained elusive to researchers. New insight into the mystery is provided by Professor David Russell, speaking at the Society for General Microbiology’s spring meeting in Edinburgh. His work could help develop innovative strategies for treating the disease.
Professor Russell and his group at Cornell University in New York, USA, have demonstrated that TB-causing bacteria are able to hijack fat metabolism in the host to drive the progression of the disease. The team’s research shows that Mycobacterium tuberculosis (Mtb) is able to stimulate macrophages, the immune cells the bacterium infects to accumulate fat droplets, turning them into “foamy” cells. This cellular transformation can trigger a reawakening of the TB infection from its latent state.
Following initial infection by Mtb, the infected immune cells in the body can clump together in the lungs in a cellular mass that is surrounded by a fibrous cuff. This containing structure, called a tubercle, physically protects the bacteria from being destroyed by the immune system. This allows them to persist inside the host for years during a latent period in which the host shows no symptoms. The respiratory infection is reactivated only in a small percentage of individuals (often those who are immune suppressed) in whom it progressively destroys lung tissue. Very little is known about the exact causes of reactivation and the relative roles of the host and the pathogen.
Professor Russell’s group discovered that inside the tubercle, surface molecules of Mtb prompted host macrophage cells to take up vast quantities of cholesterol-type lipids from the surrounding blood vessels. “We think that the lipids in the newly-formed foamy cell are then expelled into the cellular environment, which contributes to the collapse of the tubercle,” he said.
Once freed from their containing structure, the infectious bacteria are able to leak out into the airways where they can progressively destroy lung tissue. “If our model is correct, it has huge implications for vaccines and chemotherapy programs. A more detailed knowledge of the bacterium’s life cycle and its host interactions will allow us to spot new targets for drugs -- opening up new possibilities for treatment,” said Professor Russell.
Friday, April 23, 2010
Saturday, April 17, 2010
Super heavy Element 117 makes debut
PHYSICISTS have reported synthesizing element 117, the latest achievement in their quest to create "super heavy" elements in the laboratory. A paper describing the discovery has been accepted for publication in Physical Review Letters.
A team led by Yuri Oganessian of the Joint Institute for Nuclear Research in Dubna, Russia, reports smashing together calcium-48 - an isotope with 20 protons and 28 neutrons - and berkelium-249, which has 97 protons and 152 neutrons. The collisions spit out either three or four neutrons, creating two different isotopes of an element with 117 protons.
Sigurd Hofmann, a nuclear physicist at the GSI research center in Darmstadt, Germany, calls the new work on element 117 "convincing." Most elements heavier than uranium, which has 92 protons, do not exist stably in nature and must be made artificially in the laboratory.
The Russians collaborated with U.S. researchers, including from Vanderbilt University and Oak Ridge National Laboratory in Tennessee, where the berkelium target was made. Berkelium, with atomic number 97, is another of the rare artificially produced elements; the Russian team was able to obtain just 22 milligrams of it from Oak Ridge.
The researchers briefly spotted signs of element 117 during two runs of collisions lasting 70 days each. In their paper, the researchers report observing the heavier isotope of element 117 decay with a half-life of 78 milliseconds; they measured the lighter one's half-life at 14 milliseconds.
The new element, which has yet to be named, slips into a place on the periodic table between elements 116 and 118, both of which have already been discovered. Such super heavy elements are usually very radioactive and decay away almost instantly.
But many researchers think it is possible that even heavier elements may occupy an "island of stability" in which super heavy atoms stick around for a while.
A team led by Yuri Oganessian of the Joint Institute for Nuclear Research in Dubna, Russia, reports smashing together calcium-48 - an isotope with 20 protons and 28 neutrons - and berkelium-249, which has 97 protons and 152 neutrons. The collisions spit out either three or four neutrons, creating two different isotopes of an element with 117 protons.
Sigurd Hofmann, a nuclear physicist at the GSI research center in Darmstadt, Germany, calls the new work on element 117 "convincing." Most elements heavier than uranium, which has 92 protons, do not exist stably in nature and must be made artificially in the laboratory.
The Russians collaborated with U.S. researchers, including from Vanderbilt University and Oak Ridge National Laboratory in Tennessee, where the berkelium target was made. Berkelium, with atomic number 97, is another of the rare artificially produced elements; the Russian team was able to obtain just 22 milligrams of it from Oak Ridge.
The researchers briefly spotted signs of element 117 during two runs of collisions lasting 70 days each. In their paper, the researchers report observing the heavier isotope of element 117 decay with a half-life of 78 milliseconds; they measured the lighter one's half-life at 14 milliseconds.
The new element, which has yet to be named, slips into a place on the periodic table between elements 116 and 118, both of which have already been discovered. Such super heavy elements are usually very radioactive and decay away almost instantly.
But many researchers think it is possible that even heavier elements may occupy an "island of stability" in which super heavy atoms stick around for a while.
RESEARCHERS EXPLORE NUTRITIONAL VALUE OF LOCAL INSECT
IT may sound absurd but it is true. Insects like beetles, grasshoppers, termites, crickets, honeybee and caterpillar may be recommended alternative sources of protein and minerals.
THEY are easily gathered at the beginning of the rainy season in West, Central and Southern Africa when they swarm, as they are attracted to lights and can be gathered up when they land on nets or open water containers put up around a lamp. The wings are shed and can be removed by a technique similar to winnowing.
Termites are best gently roasted on a hot plate or lightly fried until slightly crisp; oil is not usually needed since their bodies are naturally high in oil.
The finished product is sold in markets in Western and eastern Nigeria as snack. Traditionally they make a welcome treat at the beginning of the rainy season when livestock is lean, new crops have not yet produced food, and stored produce from the previous growing season is running low.
Nigerian researchers have confirmed that insects are indeed a good source of protein and other nutrients. They found that edible insects constitute an important part of the daily diet of a large proportion of the population in South-Western Nigeria.
According to a study published in African Journal of Biotechnology, these insect provide high quality of proteins and supplements (minerals and vitamins) even when dried.
A. D. Banjo, O. A. Lawal; and E. A. Songonuga of the Department of Biological Sciences, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, wrote: "The consumption of non-toxic insects therefore, should be encouraged. Insects are traditional foods in most cultures, playing an important role in human nutrition and have much nutrient to offer. They can be reared for their high nutritional qualities and sold to the populace that regards them as delicacies. Some of the sought after species, especially those with high nutritional content, ought to be cultivated with modern techniques to increase their commercial values and availability."
The study is titled: "The nutritional value of 14 species of edible
Insects in south western Nigeria."
According to the study, commonly eaten insects in Nigeria are: Termites (winged adults, queen), Macrotermes bellicosus/ Macrotermes notalensis, adult crickets (Brachytrypes spp), Grasshopper (Zonocerus variegates), adult short horned grasshoppers (Cytacanthacris naeruginosus unicolor), Rhinoceros beetle larvae (Analeptes trifasciata), Scarab beetles larvae (Oryctes boas), Snout beetles larvae (Rhynchophorus phoenicis), eggs, larvae and pupae of honeybee (Apis mellifera), and larvae of caterpillars (Anaphe spp).
The researchers analysed 17 species of edible insects representing nine families from South-Western Nigeria for nutrient composition. They include the orders of Orthoptera, Lepidoptera, Coleoptera, Hymenoptera, and Isoptera. Analeptes trifasciata, Rhynchophorus phoenicis and Zonocerus variegates has the highest crude protein content (29.62, 28.42 and 26.8 per cent, respectively). The Ether Extract content ranged from 1.50 to 31.40 per cent, and the highest amount was found in R. phoenicis (31.4 per cent), Macrotermes bellicosus (28.2 per cent) and Macrotermes notalensis (22.5 per cent). The nitrogen free extract content ranged from 38.5 to 85.3 per cent, with highest values in Brachytrypes spp. and Oryctes boas.
The insect richest in Vitamin A, B2 and C was Apis mellifera (12.44 ug/100 g, 3.24 mg/100g and 10.25 mg/100 g, respectively). Highest calcium and phosphorus contents of 61.28 mg/100g and 136.4 mg/100g were found in Analeptes trifasciata. Iron was found highest in M. notalensi and magnesium in Zonocerus variegatus. These insects which are sources of delicacy are also pests of certain crops at developmental stages of their life. Despite this they constitute a significant component of diet among the people of south western Nigeria.
Until now, a number of insect or their products were used as food in some parts of Nigeria and to a large extent eaten as tit-bits or exclusively by children. Insects have played an important part in the history of human nutrition in Africa, Asia, and Latin America.
Hundreds of insect species have been used as human food, some of the more important groups include grasshopper, caterpillars, beetle grubs and sometimes adults, winged termites (some of which are very large in the tropics), bee, wasp and ant brood (larvae and pupae) as well as winged ants, cicadas, and a variety of aquatic insects.
Ordinarily, insects are not used as emergency food during shortages, but are included as a planned part of the diet throughout the year or when seasonally available. Among the numerous examples that could be cited, the Yukpa people of Colombia and Venezuela preferred certain of their traditional insect foods to fresh meat, as do the Pedi of South Africa.
Insects and meat play the same role in the human body. As food, caterpillars are regulars in the village but meat is a stranger. Most people in tropical Africa collect insects for food. The habit is especially well developed among the cultivators of the forest region. It is uncertain whether these insects are eaten because of their nutritional qualities.
The aversion to insects as human food among Europeans is nothing more than custom and prejudice Grubs of the palm weevil, Rhynchophorus phoenicis Fabr. (Coleoptera: Curculionidae), are fried and eaten in several parts of western Nigeria and in Delta and Edo States, where active marketing of the fried grubs takes place.
Imbrasia belina is the emperor moth. In its caterpillar stage, it is known as the Mopane worm and is a popular part of diets in Botswana, Northern South Africa, Zimbabwe and Namibia. Probably too popular for its own good, the worm is being eaten into extinction by the people of southern Africa.
In Uganda, the larvae of many species of the larger beetles are sought and eaten but are not as important as termites and grasshoppers in the diet. Chaoborus spp., adult lake fly, cakes are eaten and are possibly an important source of protein in Uganda.
Termites, Macrotermes bellicose, are eaten in several parts of western Nigeria. The winged adults are usually caught while on their nuptial flight or collected from the ground after they have shed their wings and then roasted for eating.
The termites are a group of asocial insects usually classified at the taxonomic rank of order Isopterans (but see also taxonomy below). Along with ants and some bees and wasps, which are all placed in the separate order Hymenoptera, termites divide labor among gender lines, produce overlapping generations and take care of young collectively.
Termites mostly feed on dead plant material, generally in the form of wood, leaf litter, soil, or animal dung, and about 10 per cent of the estimated 4,000 species (about 2,600 taxonomically known) are economically significant as pests that can cause serious structural damage to buildings, crops or plantation forests. Termites are major detritivores, particularly in the subtropical and tropical regions, and their recycling of wood and other plant matter is of considerable ecological importance.
As asocial insects, termites live in colonies that, at maturity, number from several hundred to several million individuals. Colonies use decentralized, self-organised systems of activity guided by swarm intelligence to exploit food sources and environments that could not be available to any single insect acting alone. A typical colony contains nymphs (semi-mature young), workers, soldiers, and reproductive individuals of both genders, sometimes containing several egg-laying queens. Termites are sometimes called "white ants", though they are not closely related to true ants.
In many cultures, termites are used for food (particularly the alates). The alates are nutritious, having a good store of fat and protein, and are palatable in most species with a nutty flavour when cooked.
According to a report in Proceedings of The United States National Academy of Sciences, hungry human ancestors living in southern Africa at least a million years ago had a simple approach to putting more protein and fat in their diet: They used sharpened pieces of bone to tear apart termite mounds so that they could gulp down mouthfuls of the edible insects.
Both chimpanzees and modern human foragers enthusiastically eat termites and other bugs. For the first time, though, researchers have direct evidence for this behavior in human fossil ancestors. Ancient bone tools used for digging tubers out of the ground exhibit different marks than do those used to open termite mounds.
Also, the variegated grasshopper, Zonocerus variegates (Linn.) (Orthoptera: Pyrgomorphidae), which has a large dry season population in southwestern Nigeria is reported eaten in the Akoko area of Ondo State. The larvae and pupae of honeybees, Apis
mellifera (Hymenoptera: Apidae), have a very high protein content. In southwestern Nigeria, edible insects are conceived as food and source of nutrient. Among the traditions and the customs that persist, is the consumption of various insects and usage of insects for rituals and medicinal purposes.
The researchers concluded: "This study revealed that some of the insects which are
Pests also have high nutritional qualities. Protein content of insects especially caterpillars has been studied from Central Africa, South Africa and South America.
"The result of the proximate analysis of Analeptes trifasciata from this study is similar to that obtained by Aduku (1993), Cmelik (1969), Bedford (1980) and Magdalena Sinao (1976). The ether extract, crude fibre, dry matter, moisture, nitrogen free extract and ash content level obtained generally agree with those reported by other authors investigating different insects from several parts of the world. However, the values of the proximate analysis for Brachytrypes spp. are low compared with those obtained by Chavunduka (1975). These differences may be due to variations in the dietary habits of the insects or as a result of different ecotypes. Differences may also be due to the age of the insects."
THEY are easily gathered at the beginning of the rainy season in West, Central and Southern Africa when they swarm, as they are attracted to lights and can be gathered up when they land on nets or open water containers put up around a lamp. The wings are shed and can be removed by a technique similar to winnowing.
Termites are best gently roasted on a hot plate or lightly fried until slightly crisp; oil is not usually needed since their bodies are naturally high in oil.
The finished product is sold in markets in Western and eastern Nigeria as snack. Traditionally they make a welcome treat at the beginning of the rainy season when livestock is lean, new crops have not yet produced food, and stored produce from the previous growing season is running low.
Nigerian researchers have confirmed that insects are indeed a good source of protein and other nutrients. They found that edible insects constitute an important part of the daily diet of a large proportion of the population in South-Western Nigeria.
According to a study published in African Journal of Biotechnology, these insect provide high quality of proteins and supplements (minerals and vitamins) even when dried.
A. D. Banjo, O. A. Lawal; and E. A. Songonuga of the Department of Biological Sciences, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, wrote: "The consumption of non-toxic insects therefore, should be encouraged. Insects are traditional foods in most cultures, playing an important role in human nutrition and have much nutrient to offer. They can be reared for their high nutritional qualities and sold to the populace that regards them as delicacies. Some of the sought after species, especially those with high nutritional content, ought to be cultivated with modern techniques to increase their commercial values and availability."
The study is titled: "The nutritional value of 14 species of edible
Insects in south western Nigeria."
According to the study, commonly eaten insects in Nigeria are: Termites (winged adults, queen), Macrotermes bellicosus/ Macrotermes notalensis, adult crickets (Brachytrypes spp), Grasshopper (Zonocerus variegates), adult short horned grasshoppers (Cytacanthacris naeruginosus unicolor), Rhinoceros beetle larvae (Analeptes trifasciata), Scarab beetles larvae (Oryctes boas), Snout beetles larvae (Rhynchophorus phoenicis), eggs, larvae and pupae of honeybee (Apis mellifera), and larvae of caterpillars (Anaphe spp).
The researchers analysed 17 species of edible insects representing nine families from South-Western Nigeria for nutrient composition. They include the orders of Orthoptera, Lepidoptera, Coleoptera, Hymenoptera, and Isoptera. Analeptes trifasciata, Rhynchophorus phoenicis and Zonocerus variegates has the highest crude protein content (29.62, 28.42 and 26.8 per cent, respectively). The Ether Extract content ranged from 1.50 to 31.40 per cent, and the highest amount was found in R. phoenicis (31.4 per cent), Macrotermes bellicosus (28.2 per cent) and Macrotermes notalensis (22.5 per cent). The nitrogen free extract content ranged from 38.5 to 85.3 per cent, with highest values in Brachytrypes spp. and Oryctes boas.
The insect richest in Vitamin A, B2 and C was Apis mellifera (12.44 ug/100 g, 3.24 mg/100g and 10.25 mg/100 g, respectively). Highest calcium and phosphorus contents of 61.28 mg/100g and 136.4 mg/100g were found in Analeptes trifasciata. Iron was found highest in M. notalensi and magnesium in Zonocerus variegatus. These insects which are sources of delicacy are also pests of certain crops at developmental stages of their life. Despite this they constitute a significant component of diet among the people of south western Nigeria.
Until now, a number of insect or their products were used as food in some parts of Nigeria and to a large extent eaten as tit-bits or exclusively by children. Insects have played an important part in the history of human nutrition in Africa, Asia, and Latin America.
Hundreds of insect species have been used as human food, some of the more important groups include grasshopper, caterpillars, beetle grubs and sometimes adults, winged termites (some of which are very large in the tropics), bee, wasp and ant brood (larvae and pupae) as well as winged ants, cicadas, and a variety of aquatic insects.
Ordinarily, insects are not used as emergency food during shortages, but are included as a planned part of the diet throughout the year or when seasonally available. Among the numerous examples that could be cited, the Yukpa people of Colombia and Venezuela preferred certain of their traditional insect foods to fresh meat, as do the Pedi of South Africa.
Insects and meat play the same role in the human body. As food, caterpillars are regulars in the village but meat is a stranger. Most people in tropical Africa collect insects for food. The habit is especially well developed among the cultivators of the forest region. It is uncertain whether these insects are eaten because of their nutritional qualities.
The aversion to insects as human food among Europeans is nothing more than custom and prejudice Grubs of the palm weevil, Rhynchophorus phoenicis Fabr. (Coleoptera: Curculionidae), are fried and eaten in several parts of western Nigeria and in Delta and Edo States, where active marketing of the fried grubs takes place.
Imbrasia belina is the emperor moth. In its caterpillar stage, it is known as the Mopane worm and is a popular part of diets in Botswana, Northern South Africa, Zimbabwe and Namibia. Probably too popular for its own good, the worm is being eaten into extinction by the people of southern Africa.
In Uganda, the larvae of many species of the larger beetles are sought and eaten but are not as important as termites and grasshoppers in the diet. Chaoborus spp., adult lake fly, cakes are eaten and are possibly an important source of protein in Uganda.
Termites, Macrotermes bellicose, are eaten in several parts of western Nigeria. The winged adults are usually caught while on their nuptial flight or collected from the ground after they have shed their wings and then roasted for eating.
The termites are a group of asocial insects usually classified at the taxonomic rank of order Isopterans (but see also taxonomy below). Along with ants and some bees and wasps, which are all placed in the separate order Hymenoptera, termites divide labor among gender lines, produce overlapping generations and take care of young collectively.
Termites mostly feed on dead plant material, generally in the form of wood, leaf litter, soil, or animal dung, and about 10 per cent of the estimated 4,000 species (about 2,600 taxonomically known) are economically significant as pests that can cause serious structural damage to buildings, crops or plantation forests. Termites are major detritivores, particularly in the subtropical and tropical regions, and their recycling of wood and other plant matter is of considerable ecological importance.
As asocial insects, termites live in colonies that, at maturity, number from several hundred to several million individuals. Colonies use decentralized, self-organised systems of activity guided by swarm intelligence to exploit food sources and environments that could not be available to any single insect acting alone. A typical colony contains nymphs (semi-mature young), workers, soldiers, and reproductive individuals of both genders, sometimes containing several egg-laying queens. Termites are sometimes called "white ants", though they are not closely related to true ants.
In many cultures, termites are used for food (particularly the alates). The alates are nutritious, having a good store of fat and protein, and are palatable in most species with a nutty flavour when cooked.
According to a report in Proceedings of The United States National Academy of Sciences, hungry human ancestors living in southern Africa at least a million years ago had a simple approach to putting more protein and fat in their diet: They used sharpened pieces of bone to tear apart termite mounds so that they could gulp down mouthfuls of the edible insects.
Both chimpanzees and modern human foragers enthusiastically eat termites and other bugs. For the first time, though, researchers have direct evidence for this behavior in human fossil ancestors. Ancient bone tools used for digging tubers out of the ground exhibit different marks than do those used to open termite mounds.
Also, the variegated grasshopper, Zonocerus variegates (Linn.) (Orthoptera: Pyrgomorphidae), which has a large dry season population in southwestern Nigeria is reported eaten in the Akoko area of Ondo State. The larvae and pupae of honeybees, Apis
mellifera (Hymenoptera: Apidae), have a very high protein content. In southwestern Nigeria, edible insects are conceived as food and source of nutrient. Among the traditions and the customs that persist, is the consumption of various insects and usage of insects for rituals and medicinal purposes.
The researchers concluded: "This study revealed that some of the insects which are
Pests also have high nutritional qualities. Protein content of insects especially caterpillars has been studied from Central Africa, South Africa and South America.
"The result of the proximate analysis of Analeptes trifasciata from this study is similar to that obtained by Aduku (1993), Cmelik (1969), Bedford (1980) and Magdalena Sinao (1976). The ether extract, crude fibre, dry matter, moisture, nitrogen free extract and ash content level obtained generally agree with those reported by other authors investigating different insects from several parts of the world. However, the values of the proximate analysis for Brachytrypes spp. are low compared with those obtained by Chavunduka (1975). These differences may be due to variations in the dietary habits of the insects or as a result of different ecotypes. Differences may also be due to the age of the insects."
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