Laryngeal biomechanics of the singing voice.

By transnasal fiberoptic laryngoscopy, patients with functional voice often demonstrate abnormal laryngeal biomechanics, commonly supraglottic contraction. Appropriately, such conditions are sometimes termed muscle tension dysphonias. Singers working at the limits of their voice may also transiently demonstrate comparable tension patterns. However, the biomechanics of normal singing, particularly for different singing styles, have not been previously well characterized. We used transnasal fiberoptic laryngoscopy to study 100 healthy singers to assess patterns of laryngeal tension during normal singing and to determine whether factors such as sex, occupation, and style of singing influence laryngeal muscle tension. Thirty-nine male and 61 female singers were studied; 48 were professional singers, and 52 were amateurs. Examinations of study subjects performing standardized and nonstandardized singing tasks were recorded on a laser disk and subsequently analyzed in a frame-by-frame fashion by a blinded otolaryngologist. Each vocal task was graded for muscle tension by previously established criteria, and objective muscle tension scores were computed. The muscle tension score was expressed as a percentage of frames for each task with one of the laryngeal muscle tension patterns shown. The lowest muscle tension scores were seen in female professional singers, and the highest muscle tension scores were seen in amateur female singers. Male singers (professional and amateur) had intermediate muscle tension scores. Classical singers had lower muscle tension scores than nonclassical singers, with the lowest muscle tension scores being seen in those singing choral music (41%), art song (47%), and opera (57%), and the highest being seen in those singing jazz/pop (65%), musical theater (74%), bluegrass/country and western (86%), and rock/gospel (94%). Analyzed also were the influences of vocal nodules, prior vocal training, number of performance and practice hours per week, warm-up before singing, race, smoking, and alcohol consumption.

Organ, species, and compound specificity in the metabolic activation of primary aromatic amines.

For the evaluation of the role of target tissue activation in the induction of bladder cancer, microsome-mediated N-hydroxylation of the bladder carcinogen 4-biphenylamine (4-BA) was studied in bovine and canine bladder mucosae, relative to the activity in liver. Bovine bladder microsomes mediated the N-hydroxylation of 4-BA at an exceptionally high rate, whereas no detectable activity was found with bovine liver microsomes. Dog bladder microsomes were 40-100 times less active than bovine bladder microsomes and contained approximately one-third the amount of cytochrome P450. Dog liver microsomes were as active as dog bladder microsomes per nanomole P450 and an order of magnitude more active when normalized to microsomal protein. Rat liver microsomes contained the highest level of P450 of all the preparations studied, and N-hydroxylase activity was approximately twice the rate of that of dog liver. The rate of N-hydroxylation of 2-naphthylamine (2-NA) and 1-naphthylamine (1-NA) was compared in bovine bladder mucosa and was found to correlate well with the relative potency of these compounds as bladder carcinogens (4-BA greater than 2-NA greater than 1-NA). Such a comparison could not be made with dog bladder mucosa because of its low N-hydroxylation activity. In addition, bovine bladder mucosa S-9 mutagenic activation of 4-BA, 2-NA, and 1-NA was investigated in Salmonella typhimurium and found to parallel the carcinogenic potency of these compounds. These results demonstrate considerable tissue, species, and compound specificity for the metabolic activation of aromatic amines and provide further evidence in support of bladder activation as a mechanism of aromatic amine-induced bladder cancer.

Failure of pure 1-naphthylamine to induce bladder tumors in dogs.

1-Naphthylamine was administered p.o. to beagles for approximately 9 years at a daily dose of 15 mg/kg (5 days a week). At autopsy, no tumors or other pathological changes were observed in the bladders of any of these animals. With the possible exception of the excessive accumulation of lipofuscin in the hepatocytes of these dogs, no test compound-related pathological changes in other tissues of the body were observed. Analysis of the urine revealed the presence of small amounts of N-oxidation products (1-nitrosonaphthalene plus N-hydroxy-1-naphthylamine), ranging from 2.85 to 125 microgram, following a dose of 1-naphthylamine. The theoretical significance of these findings is discussed.

Isolation of the glucuronic acid conjugate of n-hydroxy-4-aminobiphenyl from dog urine and its mutagenic activity.

The glucuronic acid conjugate of N-hydroxy-4-aminobiphenyl (NOH-4-ABP) has been isolated in relatively pure form from the urine of dogs given 4-aminobiphenyl, utilizing molecular size, ion exchange, adsorption, and partition chromatography. This conjugate is an active mutagen in Salmonella typhimurium strains TA1538 and TA98 but not in TA1535 or TA1537. NOH-4-ABP and 4-nitrosobiphenyl are also highly active in TA1538 and TA98 and inactive in TA1535 and TA1537. These observations support the concept that this conjugate is the water-soluble carrier that delivers the active metabolite to the bladder. A substance of identical chromatographic and spectral properties to the conjugate isolated from dog urine has been synthesized in low yield by the direct condensation of NOH-4-ABP with glucuronic acid. This substance yields NOH-4-ABP on dilute acid hydrolysis. Sodium (N-4-biphenylhydroxylamino-beta-D-glucopyranosid) uronate, the N-O-C isomer, was also synthesized. It was found to have differing chromatographic and chemical properties to the natural conjugate. This evidence suggests that the urinary conjugate is the compound in which conjugation has occurred with the nitrogen atom of the hydroxylamine group rather than the oxygen atom.

Cocarcinogenic interaction between D,L-tryptophan and 4-aminobiphenyl or 2-naphthylamine in dogs.

Administration of a dietary supplement of 6 g D,L tryptophan/day for 4 1/2 years following the administration of a single dose of 50 mg 4-aminobiphenyl/kg produced a bladder tumor in 1 of 4 beagle dogs. No tumors were observed in 6 dogs given the same dose of 4-aminobiphenyl without supplemental tryptophan. In a second experiment, administration of a supplement of 6 g D,L-tryptophan/day for 3 years following the administration of 5 mg 2-naphthylamine/kg/day for 30 days produced bladder tumors in 2 of 4 dogs. No tumors or other bladder pathology was produced by treatment of 4 dogs with this dose of 2-naphthylamine alone. Dogs given D,L-tryptophan alone developed no bladder tumors, but in most dogs receiving tryptophan the "tryptophan effect", i.e., a darkly stained mucosa with white areas of focal hyperplasia, was observed. Both experiments suggest a role of D,L-tryptophan as a cocarcinogen or promotor in the induction of bladder cancer.

Ethanol and oral diazepam absorption.

Despite widespread use and abuse of ethanol and diazepam in combination, little is known about the effects of ethanol on diazepam absorption. We administered diazepam (0.07 mg per kilogram of body weight) with water and with 30 ml of 50 per cent ethanol to seven normal volunteers. Plasma diazepam levels were significantly higher at 60 minutes (P less than 0.05), 90 minutes (P less than 0.01), 120 minutes (P less than 0.01), and 240 minutes (P less than 0.01) when diazepam was administered with ethanol than with water alone. Since maximum mean plasma diazepam levels after combined ingestion with ethanol were nearly twice as high than after diazepam and water (373 ng per milliliter versus 197 ng per mililiter at 60 minutes) we conclude that ethanol enhanced diazepam absorption.