Separate Primary Melanomas of the Bulbar Conjunctiva and Eyelid Skin: Clinical Implications of Multiple Primary Melanomas.

PURPOSE: We report a patient with previous in situ melanoma of the forehead skin who was referred for treatment of a bulbar conjunctival melanoma and a separate superficially invasive melanoma of the eyelid skin, and we offer a review of the biological and clinical implications of patients who have multiple primary melanomas. METHODS: This article offers a clinicopathological correlation with a review of the relevant literature. RESULTS: An 80-year-old white man was referred for evaluation of a suspicious conjunctival tumor and a lower-eyelid lesion. Excisional biopsies revealed that both were primary melanomas arising within in situ disease. Over the span of 25 years, the patient had three separate foci of in situ melanoma, two of which spawned invasive melanoma. CONCLUSION: Separate melanomas arising from the bulbar conjunctiva and eyelid skin have rarely been reported. Multiple primary melanomas of the skin, however, are not uncommon. Based on studies of persons with multiple cutaneous melanomas, the prognosis is best predicted by the tumor with the greatest depth of invasion. Patients with multiple melanomas should be examined for dysplastic nevi, additional cutaneous melanomas, and screened periodically for future lesions. Ongoing studies enrolling patients with multiple primary melanomas are attempting to generate insights into low-penetrance susceptibility genes.

HPLC methods for determination of D-aspartate and N-methyl-D-aspartate.

D-Amino acids are stereoisomers or optical isomers of naturally occurring L-amino acids and thus possess the same chemical structure, but may differ in their biological/physiological properties. Until a half century ago, D-amino acids had been considered to be unnatural substances found only in microorganisms. However, improvements in analytical instruments and methods have revealed that D-amino acids are present in invertebrates and vertebrates, including humans, and that they possess important physiological functions. D-Aspartate (D-Asp) and its methylated form N-methyl-D-aspartate (NMDA) possess neuroendocrine properties in many species. Several methods have been developed for determination of D- and L-enantiomers of amino acids by high performance liquid chromatography (HPLC). We report here improved HPLC methods for the specific determination of D-Asp and NMDA in biological tissues.

N-methyl-D-aspartic acid (NMDA) in the nervous system of the amphioxus Branchiostoma lanceolatum.

BACKGROUND: NMDA (N-methyl-D-aspartic acid) is a widely known agonist for a class of glutamate receptors, the NMDA type. Synthetic NMDA elicits very strong activity for the induction of hypothalamic factors and hypophyseal hormones in mammals. Moreover, endogenous NMDA has been found in rat, where it has a role in the induction of GnRH (Gonadotropin Releasing Hormone) in the hypothalamus, and of LH (Luteinizing Hormone) and PRL (Prolactin) in the pituitary gland. RESULTS: In this study we show evidence for the occurrence of endogenous NMDA in the amphioxus Branchiostoma lanceolatum. A relatively high concentration of NMDA occurs in the nervous system of this species (3.08 +/- 0.37 nmol/g tissue in the nerve cord and 10.52 +/- 1.41 nmol/g tissue in the cephalic vesicle). As in rat, in amphioxus NMDA is also biosynthesized from D-aspartic acid (D-Asp) by a NMDA synthase (also called D-aspartate methyl transferase). CONCLUSION: Given the simplicity of the amphioxus nervous and endocrine systems compared to mammalian, the discovery of NMDA in this protochordate is important to gain insights into the role of endogenous NMDA in the nervous and endocrine systems of metazoans and particularly in the chordate lineage.

Occurrence and neuroendocrine role of D-aspartic acid and N-methyl-D-aspartic acid in Ciona intestinalis.

Probes for the occurrence of endogenous D-aspartic acid (D-Asp) and N-methyl-D-aspartic acid (NMDA) in the neural complex and gonads of a protochordate, the ascidian Ciona intestinalis, have confirmed the presence of these two excitatory amino acids and their involvement in hormonal activity. A hormonal pathway similar to that which occurs in vertebrates has been discovered. In the cerebral ganglion D-Asp is synthesized from L-Asp by an aspartate racemase. Then, D-Asp is transferred through the blood stream into the neural gland where it gives rise to NMDA by means of an NMDA synthase. NMDA, in turn, passes from the neuronal gland into the gonads where it induces the synthesis and release of a gonadotropin-releasing hormone (GnRH). The GnRH in turn modulates the release and synthesis of testosterone and progesterone in the gonads, which are implicated in reproduction.