Brazilwood, sappanwood, brazilin and the red dye brazilein: from textile dyeing and folk medicine to biological staining and musical instruments.

Brazilin is a nearly colorless dye precursor obtained from the heartwood of several species of trees including brazilwood from Brazil, sappanwood from Asia and the Pacific islands, and to a minor extent from two other species in Central America, northern South America and the Caribbean islands. Its use as a dyeing agent and medicinal in Asia was recorded in the 2(nd) century BC, but was little known in Europe until the 12(th) century AD. Asian supplies were replaced in the 16(th) century AD after the Portuguese discovered vast quantities of trees in what is now Brazil. Overexploitation decimated the brazilwood population to the extent that it never fully recovered. Extensive environmental efforts currently are underway to re-create a viable, sustainable population. Brazilin is structurally similar to the better known hematoxylin, thus is readily oxidized to a colored dye, brazilein, which behaves like hematein. Attachment of the dye to fabric is by hydrogen bonding or in conjunction with certain metallic mordants by coordinative bonding. For histology, most staining procedures involve aluminum (brazalum) for staining nuclei. In addition to textile dyeing and histological staining, brazilin and brazilein have been and still are used extensively in Asian folk medicine to treat a wide variety of disorders. Recent pharmacological studies for the most part have established a scientific basis for these uses and in many cases have elucidated the biochemical pathways involved. The principal use of brazilwood today is for the manufacture of bows for violins and other stringed musical instruments. The dye and other physical properties of the wood combine to produce bows of unsurpassed tonal quality.

Reproducibility in monitoring nocturnal penile tumescence and rigidity.

The evaluation of sexual dysfunction has improved with the advent of methods to test nocturnal penile tumescence that also monitor penile rigidity. Earlier techniques may not have recorded abnormal rigidity despite normal tumescence. To test the reproducibility of penile tumescence and rigidity, the results of initial and repeat tracings performed a mean of 39 days apart were compared in 17 patients (median age 62 years). Three nocturnal patterns were identified. 1) Among the 17 patients the initial penile tumescence and rigidity pattern was reproduced on repeat testing in 15. 2) Patterns that were not reproduced in the other 2 patients were explained by the ingestion of alcohol or because of a febrile illness during the period monitored. 3) Nocturnal penile rigidity and tumescence tracings from these patients reproduced previous patterns. Monitoring of nocturnal penile tumescence and rigidity is a useful and reproducible tool in the evaluation of male sexual dysfunction.