Malignant tumour of the stomach. The main risk factors include a diet high in salted, smoked, or pickled foods; Helicobacter pylori infection; tobacco and alcohol use; age (over age 60); and a family history of stomach cancer. Males develop stomach cancer at approximately twice the rate of females. Symptoms may be abdominal pain or swelling, unexplained weight loss, vomiting, and poor digestion. Surgery is the only method for treating stomach cancer, although radiation therapy or chemotherapy may be used in conjunction with surgery or to relieve symptoms.
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The gastric-brooding frogs or Platypus frogs (Rheobatrachus) were a genus of ground-dwelling frogs native to Queensland in eastern Australia. The genus consisted of only two species, both of which became extinct in the mid-1980s. The genus was unique because it contained the only two known frog species that incubated the prejuvenile stages of their offspring in the stomach of the mother.
The combined ranges of the gastric-brooding frogs comprised less than 2000 km² (800 mi²). Both species were associated with creek systems in rainforests at elevations of between and and . The causes of the gastric-brooding frogs' extinction are not clearly understood, but habitat loss and degradation, pollution, and the amphibian chytrid fungus may have contributed.
The assignment of the genus to a taxonomic family is hotly debated. Some biologists class them within Myobatrachidae under the subfamily Rheobatrachinae, but others place them in their own family, Rheobatrachidae.
Both species of gastric-brooding frogs were very different in appearance and behaviour to other Australian frog species. Their large protruding eyes and short, blunt snout along with complete webbing and slimy bodies differentiated them from all other Australian frogs. The largely aquatic behaviour exhibited by both species was only shared (in Australia) with the Dahl's Aquatic Frog and their ability to raise their young in the mother's stomach was unique among all frogs.
The Southern Gastric-brooding Frog was a dull grey to slate coloured frog that had small patches, both darker and lighter than the background colouration, scattered over dorsal surface (back). The ventral surface was white or cream, occasionally with yellow blotches. The arms and legs had darker brown barring above and were yellow underneath. There was a dark stripe that ran from the eye to the base of the forelimb. The ventral surface (belly) was white with large patches of cream or pale yellow. The toes and fingers were light brown with pale brown flecking. The end of each digit had a small disc and the iris was dark brown. The skin was finely granular and the tympanum was hidden. The male Southern Gastric Brooding Frog was to in length and the female to in length.
The call of the Southern Gastric-brooding Frog has been described as an "eeeehm...eeeehm" with an upward inflection. It lasts for around 0.5 of a second and was repeated every 6-7 seconds.
Being a largely aquatic species the Southern Gastric-brooding Frog was never recorded more than 4 m (13 ft) from water. Studies by Glen Ingram showed that the movements of this species were very restricted. Of ten juvenile frogs, only two moved more than 3 metres between observations. Ingram also recorded the distance moved along a stream by seven adult frogs between seasons (periods of increased activity, usually during summer). Four females moved between 1.8-46 m (6-151 ft) and three males covered 0.9-53 m (3-174 ft). Only three individuals moved more than 5.5 m (18 ft) (46 m, 46 m and 53 m). It appeared that throughout the breeding season adult frogs would remain in the same pools or cluster of pools, only moving out during periods of flooding or increased flow.
Male Northern Gastric-brooding Frogs call from the water's edge during summer. The call was loud, consisting of several staccato notes. It is similar to the Southern Gastric-brooding Frogs call although deeper, shorter and repeated less often.
Eggs found in females measured up to 5.1 mm in diameter and had large yolk supplies. These large supplies are common among species that live entirely off yolk during their period of development. Most female frogs possessed around 40 ripe eggs, this number is almost double that of the number of juveniles ever to be observed occurring in the stomach (21-26). This means one of two things, that the female fails to swallow all the eggs or the first few eggs to be swallowed are digested.
At the time the female ingests the fertilized eggs her stomach was no different from that of any other frog species. In the jelly that surrounded each egg was a substance called prostaglandin E2 (PGE2). This substance had the ability to turn off the production of hydrochloric acid in the stomach. This source of PGE2 was enough to cease the production of acid during the embryonic stages of the developing eggs. Once the eggs had hatched the tadpoles too created PGE2. The mucus excreted from the tadpoles gills contained the PGE2 necessary to maintain the stomach in a non-functional state. These mucus excretions do not occur in tadpoles of most other species. Tadpoles that don't live entirely off a yolk supply still produce mucus cord, but the mucus along with small food particles travels down the oesophagus into the gut. With Rheobatrachus (and several other species) there is no opening to the gut and the mucus cords are excreted. During the period that the offspring were present in the stomach the frog did not eat.
Information on tadpole development was observed by a group that was regurgitated by the mother and successfully raised in shallow water. During the early stages of development tadpoles lacked pigmentation, but as they aged they progressively develop adult colouration. Tadpole development took at least six weeks, during this time the size of the mother’s stomach continued to increase until it largely filled the body cavity. The lungs deflated and breathing relied more upon gas exchange through the skin. Despite the mothers increasing size she still remained active.
The birth process was widely spaced and may have occurred over a period of as long as a week. However, if disturbed the female may regurgitate all the young frogs in single act of propulsive vomiting. The offspring were completely developed when expelled and there was little variation in colour and length of a single clutch.
Populations of Southern Gastric-brooding Frogs were present in logged catchments between 1972 and 1979. The effects of such logging activities upon Southern Gastric-brooding Frogs was not investigated but the species did continue to inhabit streams in the logged catchments. The habitat that the Southern Gastric-brooding Frog once inhabited is now threatened by feral pigs, the invasion of weeds, altered flow and water quality problems caused by upstream disturbances. Despite intensive searching, the species has not been located since 1979 or 1981 (depending on the source).
The Eungella National Park, where the Northern Gastric-brooding Frog was once found, was under threat from bushfires and weed invasion. Continual fires may have destroyed or fragmented sections of the forest. The outskirts of the park are still subject to weed invasion and the chytrid fungus has been located within several rainforest creeks within the park. It was thought that the declines of the Northern Gastric-brooding Frog during 1984 and 1985 were possibly normal population fluctuations. Despite continued efforts to locate the Northern Gastric-brooding Frog it has not been found. The last reported wild specimen was seen in 1980
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