Biomedical subjects
Publications and source records attributed to N A Romas.
A technique is recommended to repair urinary fistulas vaginally using a pedicle of labial fat to separate the urothelial and vaginal layers. The technique was used in 6 patients with vesicovaginal and 4 patients with urethrovaginal fistulas. Anatomic results were successful in all cases and stress incontinence was cured in all patients who had this coexistent condition.
The 24-hour urinary carcinoembryonic antigen determinations were performed on 61 patients with different stages of bladder carcinoma. Elevated titers were found in 81 per cent of the patients with active tumors and falsely positive studies were found in 7 per cent. High stage lesions were found to have high carcinoembryonic antigen levels. Plasma carcinoembryonic antigen determinations were elevated in only 45 per cent of the patients with active tumors but further study may be warranted in advanced bladder cancer cases. The 24-hour urinary carcinoembryonic antigen measurements yield the highest percentage elevations in bladder carcinoma and further investigation is required to better define its clinical application.
The tryptophan loading test and cutaneous antigen test were done on 55 patients with various stages of bladder cancer. Patients with an abnormality of tryptophan metabolism showed a greater degree of unreactivity to cutaneous delayed hypersensitivity testing. Of the 23 patients with normal tryptophan metabolism 47 per cent were unreactive to 2 or 3 skin antigens. Of 13 patients with 1 abnormal tryptophan metabolite 62 per cent were unreactive to 2 or 3 skin antigens. Of 19 patients with 2 or more abnormal tryptophan metabolites 68 per cent were unreactive to 2 or 3 antigens.
Abnormal tryptophan metabolism in patients with bladder carcinoma has been reported to have an extremely high correlation with future tumor recurrences. The methods for determination of these urinary metabolites have not been applicable for routine clinical use in the past. A new method is described using thin layer chromatography followed by fluorescent scanning with the SD 3000 spectrodensitometer. The range of recovery for the 6 tryptophan metabolites was from 96.9 to 106.7 per cent. In our study 31 per cent of the male and 50 per cent of the female bladder cancer patients had 2 or more abnormal tryptophan metabolites.
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Androgens and estrogens are well-known to initiate their actions by binding to specific intracellular receptors. The steroid-receptor interaction, the receptors, and the details of transcriptional activation consequent to the binding of these steroids with their respective receptors have been, and continue to be, intensively studied. More recently, it has become increasingly apparent that steroids may interact with cells by other than this classic pathway. This communication will deal with activation by sex hormones of a signal transduction pathway that originates at the cell membrane and utilizes cyclic adenosine monophosphate (cAMP) as a second messenger. The system consists of three components, an agonist steroid, sex hormone-binding globulin (SHBG), and a membrane receptor (R(SHBG)) for SHBG. SHBG is a well-characterized plasma protein that has two binding sites, one binds certain estrogens and androgens, and the other binds to R(SHBG). The characteristics of this novel signal transduction system, from the interaction of SHBG with R(SHBG), to the intermediacy of G-proteins, to cAMP generation, to downstream effects of the second messenger will be reviewed.
Sex hormone-binding globulin is a plasma glycoprotein that binds certain estrogens and androgens with high affinity. Over the past several years it has been shown that, in addition to functioning as a regulator of the free concentration of a number of steroid hormones, SHBG plays a central role in permitting certain steroid hormones to act without entering the cell. The system is complex. SHBG interacts with a specific, high affinity receptor (R(SHBG)) on cell membranes that appears to transduce its signal via a G protein. The SHBG-R(SHBG) complex causes the activation of adenylyl cyclase and the generation of cAMP within a matter of minutes after exposure to an appropriate steroid. Only steroids that bind to SHBG can activate SHBG-R(SHBG), but not all steroids that bind have this function, e.g. are agonists. All steroids that bind to SHBG but do not activate adenylyl cyclase are antagonists. The signals generated by the steroid-SHBG-R(SHBG) complex generate messages that have effects on the transcriptional activity of classic, intracellular receptors for steroid hormones. These and other downstream effects of this system are reviewed.
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