Age-related changes in GH secretion were studied in the dog. In preliminary experiments, administration of GH-relasing hormone (GHRH-40, 2 \g=m\g/kg,iv) or the \g=a\2-adrenoceptor agonist clonidine (4 \g=m\g/kg,iv) elicited significantly higher plasma GH rises in 3 to 4 years old than in 10 to 14 years old beagle dogs. The pulsatile patterns of GH secretion in both young and old dogs under baseline conditions and after prolonged fasting or clonidine administration were studied. Samples were taken every 10 min from 09.00 to 15.00 h from five young and five old dogs of both sexes. Under baseline conditions, GH peak frequency, total peak area, and integrated GH secretion were significantly lower in old than in young dogs. In old dogs, 5-day complete fasting or 14\ x=r eq-\ day clonidine administration (75 \g=m\g/dog,po, twice daily) increased the frequency and amplitude of spontaneous GH bursts, the total peak area, and the integrated GH secretion. After either stimulus, the GH secretory pattern was quantitatively and qualitatively indistinguishable from that of young dogs under baseline conditions. Similarly, the foregoing indices were significantly increased in young dogs by either stimulus, except for the inability of clonidine to affect peak frequency. These data demonstrate that the defective GH secretion in old dogs is not irreversible, since it is normalized when old dogs are exposed to central nervous system-directed stimuli.Among the several causes proposed for the geria¬ tric changes in structure and function, one is cessa¬ tion of endogenous growth hormone secretion, which occurs in about half of the elderly popula¬ tion (1). There are some similarities between the al¬ terations in ageing and those that occur in GHdeficient patients. In both, there are shrinkage of lean body mass, expansion of adipose mass, dim¬ inution of renal function, and decreased rates of cell division (1). In addition, both kinds of subjects have reduced bone mass and density, dental defi¬ cits, and a decrease in calcium absorption. Consist¬ ent with this proposition, one third of a large group of old subjects (55-80 years) had very low levels of somatomedin-C (2), the GH-related peptide that mediates most of the biological effects of GH (3).If defective GH secretion is one of the pacema¬ kers of ageing, it is of interest to study the mechan¬ isms underlying reduced GH secretion in aged hu¬ mans and animals (2,4-6), with the ultimate goal being to develop suitable pharmacological means for counteracting the age-related phenomena. The present studies were performed in the dog, a species with many aspects of GH regulation resem¬ bling those in humans (7,8).After an initial assessment of the ability of old and young dogs to respond to acute challenges with GH-releasing hormone (GHRH) or clonidine, an a-adrenergic agonist (9), dogs were fasted for a long period or given clonidine, two known stimuli for GH secretion in this species (10)(11)(12), and the ability of these stimuli to alter the secretory pat¬ tern of GH was evaluated over a...

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e17535 Background: Juvenile Cancer (JC) involves patients between 18 and 29 years old (adult pt less than 30 yo) and can be or not associated to AIDS. The non-AIDS JC pt challenge the clinical oncologist in many ways: there are few preventive measures, avoiding delayed toxicities is mandatory (fertility, cognitive impairment) and there is a lack of evidence-based treatments for uncommon tumors. The aim of this paper is to evaluate the incidence and clinical outcome of JC non AIDS related at the IOHM. Methods: A JC search in the patient database of the IOHM was made. The inclusion criteria was: new cancer pt diagnosed between 18 and 29 yo. The following variables were analyzed: age, gender, date, absolute and relative annual incidence and diagnosis. The tumors were classified as expected (germinal, hematological, sarcoma, melanoma, CNS, thyroid, cervix, trophoblastic disease) or unexpected (breast, colon, ovarian, gastric, pancreatic, head and neck). The Mean Annual New Case (MANC) incidence for pt older than 30 yo (non-JC) and JC in two different four year periods (“A”: 2001–2004, “B”: 2005–2008) were calculated in order to analyze the relative risk between both populations for these periods. Results: A total of 12.828 new pt were managed at the IOHM between January 2001 and January 2008, with 336 of them (2.6%) being JC. Mean age (range) = 23.3 years (18–29). Gender: male = 180 (53%) and female = 156 (47%). Diagnosis: Expected tumors 269 pt (80%) (testicular tumors = 89 pt; lymphoma = 75 pt; sarcoma = 35 pt; melanoma = 17 pt; others = 53), Unexpected tumors 67 pt (20%) (gastrointestinal = 23 pt; breast cancer = 17 pt; ovarian = 13 pt; head and neck = 7 pt; others = 7 pt). MANC for Non JC in A=1458.25 pt/y; MANC for Non JC in B = 1748.75 pt/y (RR Non JC B/A = 1.2). MANC JC in A = 18.5 pt/y; MANC JC in B = 52.75 pt/y (RR JC B/A = 2.85). Conclusions: 1) In our database, 336 cases of JC out of 12.828 new cancer patients between were found 2001 and 2008; 2) Expected tumors represent 80% of the cases; 3) An unexplained trend of new cases of JC is seen in this 8-year period. The comparison of the first 4 years and the second 4 years shows a relative risk increase of 300% of cases in this population. If other investigators confirm this data, a severe public health problem may be unrecognized. No significant financial relationships to disclose.