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A Argyriou

Publications and source records attributed to A Argyriou.

7 recordsLinked to original sources

Melatonin facilitates short-term memory.

The olfactory social memory test, based on the recognition of a juvenile rat by a male adult rat, was used to investigate whether melatonin influences memory. Intracerebroventricular (i.c.v.) injection of 1.1 nmol melatonin shortened recognition time, while the melatonin ML1 receptor antagonist luzindole (1 nmol) exerted the opposite effect. The facilitating influence of melatonin was abolished in the presence of 0.5 nmol luzindole. The findings suggest that endogenous melatonin facilitates short-term memory.

Animals↗

Neonatal screening for Duchenne muscular dystrophy: a novel semiquantitative application of the bioluminescence test for creatine kinase in a pilot national program in Cyprus.

The objectives of this study were to evaluate a novel semiquantitative application of the bioluminescence test for screening newborns for Duchenne muscular dystrophy (DMD) and to use this technique in a pilot national program. The study was performed on the island of Cyprus, which provides ideal conditions for maximizing the prevention rate due to the small size of the country, the well-defined population, and the high degree of awareness of the public concerning genetic diseases. Guthrie spots were obtained through the national screening center for phenylketonuria and congenital hypothyroidism. The bioluminescence method for measuring creatine kinase (CK) in dried blood spots was adapted for use in a semiquantitative way. During the first 6 years of the program (1992-1997), we screened 30,014 samples and found 43 with initially high CK values. We were able to obtain repeat specimens in 35 cases. Of the repeat samples, 30 were found to have normal activity, giving a false-positive rate of 0.10%. Five boys had persistent CK elevations and were confirmed to be DMD or Becker (BMD) cases by DNA analysis and/or dystrophin analysis. The semiquantitative application of the bioluminescence assay of CK that we have introduced has proved to be a fast and reliable method for screening large numbers of samples for DMD. It has a low rate of false positives, which compares favorably with that of other DMD screening programs. Although it is early to evaluate its impact fully, the program seems to be bringing about the anticipated benefits to affected families.

Creatine Kinase↗

Histaminergic neurons facilitate social memory in rats.

The social memory test was used so as to investigate whether brain histamine is involved in short-term memory. Histamine injected intracerebroventricularly (i.c.v.) decreased investigation time of a juvenile rat by an adult rat. A similar effect was elicited by i.c.v. administration of histidine. Compared with the control animals, rat pretreatment with alpha-fluoromethylhistidine (FMH), which inhibits neuronal synthesis of histamine, prolonged recognition time. The H3-receptor agonist immepip also prolonged investigation time, while the H3-antagonist thioperamide exerted the opposite effect. Treatment with histidine increased, while treatment with FMH decreased histamine levels in various brain regions. It is concluded that histamine released from histaminergic neurons facilitates short-term memory.

Animals↗

Steroidogenesis in the two enriched-Leydig cell populations of human testis: evidence for a positive control by seminiferous tubules secreted factor(s).

In two different enriched populations of Leydig cells (called FI and FII) obtained from human testes (young patients: mean age 36 +/- 3 years, n = 6; aged men: mean age 73 +/- 2 years, n = 5), the dehydroepiandrosterone and testosterone in vitro outputs were increased in a dose- and time-related manners by hCG. Similar results were obtained when the Leydig cells were incubated in presence of either dbcAMP or 22R-hydroxycholesterol. In presence of either hCG or dbcAMP, the coefficient of stimulation (in terms of steroid outputs) was higher in FII when compared to FI. Conversely, the basal production of steroids was greater in FI than in FII, mainly for testosterone. The addition of increasing amounts of seminiferous tubule culture medium (STM) to the Leydig cell incubation medium led to a dose-related enhancement of the steroid production in both enriched-Leydig cell fractions under basal and hCG-stimulated conditions. Similar results were obtained in presence of increased seminiferous tubules length. Additional experiments realized with either concentrated STM or the coculture of seminiferous tubules with purified Leydig cells have confirmed the existence of a paracrine control of Leydig cell steroidogenesis by seminiferous secreted factor(s). A paracrine factor (or factors) from seminiferous tubular origin influences positively and with a high efficiency the Leydig cell function in humans, whatever the age.

Adult↗