Taste disorder in hypo and hyperthyroidism.

Gustatory responses to the basic taste substances (sweet, salty, sour and bitter) were studied in hypothyroid and hyperthyroid subjects. The intensity and hedonic responses were evaluated using "category scaling" for 7 concentrations of glucose, sodium chloride, citric acid and quinine sulphate. The intensity and hedonic values decrease in hyperthyroidism for salt and bitter solution, and sourness is perceived as more unpleasant. In hypothyroid subjects intensity and hedonic value decreases for sweetness, the pleasant responses to salt and bitter increase, though intensity perception decreases for bitter solutions.     

Differences in smoking-related variables based on phenylthiocarbamide "taster" status

Test strips impregnated with phenylthiocarbamide (PTC) have been used to identify genetic differences based on whether a bitter taste is perceived. To determine whether smokers who perceive PTC as bitter tasting ("tasters") would differ from those who describe it as tasteless ("non-tasters") on smoking-related variables, we studied 464 current smokers (70% female, 79% White; mean age 30.5+/-9 years) recruited to participate in laboratory experiments and clinical trials. Of these, 217 (47%) reported the PTC strips as tasteless and 154 (33%) as tasting bitter. The remaining 93 (20%) described the taste as salty, sweet, or other and were excluded from further analyses. Comparing tasters with non-tasters, we found significant differences in mean (S.D.) total years smoked (14.5 [9.2] for non-tasters, vs. 12.6 [8.4] for tasters, p<.05), Fagerstrom Tolerance Questionnaire scores (6.4 [2.1] vs. 5.8 [2.1], p<.01), and scores on the Positive Reinforcement scale of the Michigan-Nicotine Reinforcement Questionnaire (8.1 [2.9] vs. 6.8 [3.1], p<.05). Results suggest that among smokers, ability to taste PTC may confer some protection from development of nicotine dependence and positive reinforcement from smoking.     

Does a reduced sensitivity to bitter taste increase the risk of becoming nicotine addicted?

Cigarette smoking appears to be on the increase in adolescents. The initiation of regular smoking nearly always begins before adulthood. It is therefore crucial to find ways of identifying those children most vulnerable to nicotine addiction and prioritizing them for preventive measures. We hypothesized that individuals who, in a simple taste test, perceive phenylthiocarbamide (PTC) as bitter may find the taste of cigarettes aversively bitter and could therefore have a reduced vulnerability to nicotine addiction compared to nontasters, who would be the group at greater risk of addiction. We studied 242 Plains American Indians, 136 women and 106 men aged 18-59 years, and found that (allowing for gender differences and the possible direct effects of smoking on taste) the proportion of PTC nontasters to tasters in smokers, even light smokers, was significantly greater than in both nonsmokers and social smokers (chi2= 15.875, 4 df; P=.003), suggesting that nontasters, who are not aversive to the bitter taste of cigarettes, may be more at risk for heavy smoking and therefore more vulnerable to nicotine addiction.     

The study of tasters and non-tasters of phenyl-thio-carbamide (PTC) and its relation to blood groups

The ability to taste phenyl-thio-Carbamide (PTC) is one of the gene marker systems which provides one of the means to reconstruct relationships of ethnic groups of man. In 433 Maharashtrian subjects the ability to taste PTC was studied by Harris and Kalmus method. At the same time, blood groups of these subjects were determined by slide agglutination method. It was found that 63.74% of local population was taster and 36.26% non-taster. The percentage of non-tasters was higher in males, than in females. No significant relation was found between the ability to taste PTC and the blood groups. The results were compared with those observed by other workers and it was found that the percentage of non-tasters in local population in the present study was similar to that found in Indian elsewhere.     

Oxazepam pharmacokinetics in thyroid disease.

The pharmacokinetics of oxazepam, a drug mainly eliminated by a single step glucuronidation reaction, were studied in seven hyperthyroid and six hypothyroid patients before and after treatment. Oxazepam elimination half-life was shorter and apparent oral clearance higher in untreated hyperthyroid patients than after treatment. There was no significant change in oxazepam elimination in hypothyroid subjects. Time to peak concentration (tmax) was reduced in the hyperthyroid state. Hypothyroidism had no significant effect on tmax. Serum bilirubin concentration was lower in the patients while hyperthyroid before treatment than when euthyroid and also lower than in the hypothyroid patients. There was no significant correlation between serum bilirubin concentrations and oxazepam elimination. These results suggest that glucuronyl transferase activity is increased in hyperthyroidism but is not altered in most patients with hypothyroidism. The extent of increase in glucuronyl transferase activity is similar to that produced by enzyme inducing drugs.     

A double-blind study of the influences of eszopiclone on dysgeusia and taste function

Taste disturbance is a common, but poorly understood, side effect of a large number of medications. This double-blind study examined the frequency, intensity, and quality of taste disturbances related to the widely used hypnotic sleep aid eszopiclone (ESZ; Lunesta^®), as well as their associations with age, sex, body mass index (BMI), time of day, phenyl thiocarbamide (PTC) taste sensitivity, and ESZ saliva and blood levels. Sixty six percent of 24 female subjects and 53% of 15 male subjects reported dysgeusic sensations, mostly bitter/metallic, during the drug administration (respective placebo figures 17% and 7%). No meaningful relationships were found between the frequency or the intensity of the sensations and age, BMI, or PTC taste sensitivity. Dysgeusia was more intense and longer lasting in women than in men, stronger in the morning than in the evening, and positively correlated with drug plasma and saliva levels. In women, intensity ratings decreased across treatment days. Taste test measures were marginally, at best, influenced by ESZ. This study demonstrates, for the first time, that the dysgeusia associated with ESZ is systemically influenced by a number of factors, including sex, time since drug administration, and both blood and saliva levels of the drug.     

Taste function in methadone-maintained opioid-dependent men

It has been shown repeatedly that opioid dependence is associated with increased consumption of refined sugars. It is possible that this association results from altered taste reactivity in opioid-dependent subjects. Thus, in the present study, we compared taste responses to sweet, bitter, sour and salty solutions in methadone-maintained opioid-dependent men and healthy control subjects. The two groups did not differ in terms of rated intensity or pleasantness of sucrose (1-30%), quinine (0.001-0.005%), citric acid (0.02-0.1%) and sodium chloride (0.18-0.9%) solutions. Proportions of 'sweet-likers', i.e. subjects rating a 30% sucrose (0.88 M) solution as the most pleasant, were also similar in both groups. In line with the previous findings, the methadone-maintained subjects reported adding more table sugar to caffeinated beverages. The results of the present study suggest that changes in taste reactivity may not be responsible for altered dietary choices in opioid addicts.     

Pharmacokinetics of theophylline in hyperthyroid and hypothyroid patients with chronic obstructive pulmonary disease

Summary The pharmacokinetics of theophylline was investigated in five hyperthyroid, five hypothyroid, and five euthyroid patients, all with chronic obstructive pulmonary disease. Wide individual variability was found in theophylline kinetics, but the rate of elimination of theophylline was significantly higher in hyperthyroid, and lower in hypothyroid patients than in the euthyroid patients (k_el=0.155, 0.060 and 0.107 h^–1, respectively). The values for clearance and volume of distribution were not consistently changed compared with those in the euthyroid group, although all the parameters except AUC were significantly different in hyperthyroid and hypothyroid patients. There was a positive correlation between both thyroxine and triiodothyronine serum concentrations and total body clearance of theophylline (r=0.795 and r=0.791, respectively). It is concluded that in spite of the wide interindividual variability and the relatively small differences in the pharmacokinetics of theophylline in thyroid dysfunction compared with the euthyroid status, these differences have to be considered in certain clinical situations, as they may require changes in the therapeutic regimen for administration of theophylline in hyperthyroid or hypothyroid patients.     

Catecholamine sensitivity in hyperthyroidism and hypothyroidism.

1. Catecholamine sensitivity in hyper- and hypothyroidism has been studied using a standardised isoprenaline sensitivity test. 2. Seven patients with hyperthyroidism and seven with hypothyroidism were tested both when showing evidence of thyroid dysfunction and again when euthyroid. 3. No significant differences were seen in heart rate responses to isoprenaline when patients became euthyroid compared to their response when either hyperthyroid or hypothyroid. 4. These results indicate that sensitivity to catecholamines is not altered in thyroid dysfunction and, in particular, that hypersensitivity does not occur in spontaneous hyperthyroidism.     

Gustatory signaling in the periphery: detection, transmission, and modulation of taste information

Gustatory signaling begins with taste receptor cells that express taste receptors. Recent molecular biological studies have identified taste receptors and transduction components for basic tastes (sweet, salty, sour, bitter, and umami). Activation of these receptor systems leads to depolarization and an increase in [Ca(2+)](i) in taste receptor cells. Then transmitters are released from taste cells and activate gustatory nerve fibers. The connection between taste cells and gustatory nerve fibers would be specific because there may be only limited divergence of taste information at the peripheral transmission. Recent studies have demonstrated that sweet taste information can be modulated by hormones or other endogenous factors that could act on their receptors in a specific group of taste cells. These peripheral modulations of taste information may influence preference behavior and food intake. This paper summarizes data on molecular mechanisms for detection and transduction of taste signals in taste bud cells, information transmission from taste cells to gustatory nerve fibers, and modulation of taste signals at peripheral taste organs, in particular for sweet taste, which may play important roles in regulating energy homeostasis.     

Influence of thyroid hormone on the phospholipid composition of lung tissue and surfactant of rats

Thyroid hormone is an important regulator of lipid metabolism in vivo. The effect of thyroid hormone on the phospholipid composition of lung tissue and surfactant has been studied in hypothyroid and hyperthyroid rats in comparison with the control rats. Rats were made hyperthyroid by administering 1 mg of L-thyroxine/kg body weight for six days. Another group of rats was rendered hypothyroid by injecting 1 mci of Na I131 to each rat. Phosphatidyl choline, lysophosphatidyl choline, lysophosphatidyl ethanolamine, phosphatidyl ethanolamine, and sphingomyclin, were estimated by thin layer chromatography. A decrease in phospholipids in hypothyroid and an increase in the hyperthyroid rats was observed. This can be attributed to the altered thyroid activity.     

Influence of altered thyroid state on the inotropic potency of isoproterenol--studies with isolated rat left atria paced at different frequencies

The influence of thyroid status upon the inotropic effect of isoproterenol has been examined using left atrial preparations isolated from hypothyroid, control (untreated), and hyperthyroid rats. Atria were paced at 5 Hz with submaximal field pulses, and isoproterenol was added cumulatively. Mean maximum inotropic responses to isoproterenol were 1.4 mN (hypothyroid), 1.2 mN (control), and 0.3 mN (hyperthyroid). Analysis of log concentration-fractional response curves revealed that isoproterenol was approximately 10 times less potent in preparations from hypothyroid rats. In preparations from hyperthyroid rats, the potency of isoproterenol was similar to that observed in control preparations. These results cast doubt upon the functional significance of the increased responsiveness to isoproterenol observed in other studies in which atria were paced at low frequencies. When applied at a concentration approximating the appropriate EC50 to atria paced at varying frequencies (1, 3, 5, and 5.8 Hz), isoproterenol enhanced contractile force developed in response to stimulation at the lower frequencies in atria from hypothyroid rats, and depressed the response of atria from hyperthyroid rats to stimulation at the higher frequencies.     

甲状腺素对大鼠脂肪组织解偶联蛋白 2基因表达的影响

目的：探讨甲状腺素对大鼠白色脂肪组织(WAT)解偶联蛋白 2(UCP2)基因表达的影响.方法：正常雄性Wistar大鼠30只,随机分为3组,对照组、甲状腺功能亢进(甲亢)组和甲状腺功能低下(甲低)组,每组10只,应用左甲状腺素钠和甲巯咪唑分别造成大鼠甲亢和甲低状态;用放射免疫法检测血清总三碘甲状腺原氨酸(T3)、甲状腺素(T4)的浓度;半定量RT PCR法检测WAT中UCP2 mRNA的表达水平.结果：与对照组相比,甲亢组大鼠WAT中UCP2 mRNA的水平增加1.4倍,甲低组大鼠WAT中UCP2 mRNA的水平降低20%(均P＜0.01).结论：甲状腺素对WAT中UCP2基因的表达具有上调作用     

DISEASE-INDUCED CHANGES IN α-ADRENOCEPTOR-MEDIATED CARDIAC AND VASCULAR RESPONSES IN RATS

1. The physiological relevance of cardiac and vascular α-adrenoceptors may increase in disease states in which β-adrenoceptors are altered. To test this, positive inotropic and vasoconstrictor responses to phenylephrine were measured in isolated tissues from rats with experimentally-induced hyperthyroidism, hypothyroidism and diabetes as well as in genetically spontaneous hypertensive rats (SHR). 2. In left atria, positive inotropic responses to phenylephrine were increased in hypothyroid and diabetic rats and abolished in hyperthyroid and SHR. 3. In contrast, phenylephrine produced increased positive inotropy in left ventricular papillary muscles from hyperthyroid rats, increased potency in diabetic rats and negative inotropic responses in hypothyroid rats. 4. The potency of phenylephrine as a vasoconstrictor in thoracic aortic rings was increased in hyperthyroid and SHR and decreased in hypothyroid rats. 5. Thus, disease states which alter β-adrenoceptor responsiveness can independently regulate atrial, ventricular and vascular responses to the α₁-adrenoceptor agonist, phenylephrine. Therefore, these disease states may alter the physiological control of the cardiovascular system by noradrenaline and adrenaline as well as the responsiveness in disease states to therapeutic agents acting via α-adrenoceptors.     

甲状腺功能低下与亢进大鼠模型的几项生化指标的检测

目的:探讨甲状腺功能低下(甲低)及甲状腺功能亢进(甲亢)模型大鼠的甲状腺功能改变对血钙和血磷的影响。方法:制备甲低及甲亢大鼠模型,测定其血清T3、T4、TSH、钙、磷的含量变化。结果:甲低大鼠血清T3、T4和TSH浓度分别为0.27±0.08nm o l/L、25.87±2.83nm o l/L和3.36±0.42mU/L,与对照组血清T3(0.97±0.11nm o l/L)和T4(68.74±7.57nm o l/L)相比较,均明显降低(P<0.0001),有极显著差异;而血清TSH较对照组TSH含量(1.72±0.43mU/L)显著升高(P<0.0001)。甲亢大鼠T3(9.24±1.56 nm o l/L)和T4(155.73±13.98nm o l/L)含量比对照组均显著升高(P<0.0001),而TSH含量仅为0.37±0.06mU/L,与对照组相比明显降低(P<0.0001)。对照组血钙(C a2+)和血磷(HPO42-)含量分别为2.37±0.30mm o l/L和2.56±0.10mm o l/L;甲低组血钙为2.27±0.15mm o l/L,血磷为2.33±0.10mm o l/L;甲亢组血钙含量为6.17±1.42mm o l/L,血磷含量为3.84±1.13mm o l/L。结论:甲亢大鼠血钙和血磷含量较正常大鼠明显升高。甲低大鼠血清钙、磷含量与对照组大鼠比较均有所下降,但无统计学意义。     

Unaltered metabolism of phenytoin in thyroid disorders

The metabolism of phenytoin was studied in 9 hyperthyroid and 7 hypothyroid patients before and after treatment with either antithyroid drugs or 1-thyroxine. No difference in the half-life, volume of distribution and metabolic clearance rate was found between untreated hyper- and hypothyroid subjects. Furthermore, normalisation of thyroid function test did not change the kinetic parameters of phenytoin. The results indicate that the well-known correlation between thyroid function and antipyrine kinetics cannot be extrapolated uncritically to other drugs. It is concluded that no general rules are valid in the kinetics among different drugs in thyroid pathological conditions. Each drug must be evaluated by itself in different pathological conditions.     

Taste differences between cigarette smokers and nonsmokers

In a series of taste tests, cigarette smokers allowed to smoke, cigarette smokers not allowed to smoke, and nonsmokers, rated the pleasantness and intensity of sugar, salt, and quinine solutions. One taste test was performed before, and three tests were completed after, ingestion of a glucose load. Before the glucose load, there were no significant differences between the groups in rating test solutions. After the glucose load, the smokers allowed to smoke significantly decreased their ratings of the pleasantness of very sweet solutions. In contrast, nonsmokers and smokers-not-smoking did not significantly decrease their ratings of the pleasantness of sweet tastes. None of the subjects significantly changed their intensity ratings after the glucose load, nor did they change their pleasantness and intensity ratings of salt and quinine solutions.     

Ophthalmic Graves's disease: natural history and detailed thyroid function studies

Of 27 patients with ophthalmic Graves's disease (OGD) who had been clinically euthyroid three years previously, one became clinically hyperthyroid and seven overtly hypothyroid. Improvement in eye signs was associated with a return to normal of thyroidal suppression by triiodothyronine (T3) and of the response of thyroid-stimulating hormone (TSH) to thyrotrophin-releasing hormone (TRH). Of a further 30 patients with OGD who had not been studied previously, three were overtly hypothyroid. Of the combined series, 46 patients were euthyroid, 18 (40%) of whom had an impaired or absent TSH response to TRH, and 3(6-7%) an exaggerated response. Eleven out of 37 patients (29-7%) had abnormal results in the T3 suppression test. There was a significant correlation between thyroidal suppression by T3 and the TSH response to TRH. Total serum concentrations of both T3 and thyroxine (T4) were closely correlated with T3 suppressibility and TRH responsiveness. Free T4 and T3 (fT3) concentrations were normal in all but three patients, in whom raised fT3 was accompanied by abnormal TSH responses and thyroidal suppression. The presence of normal free thyroid hormone concentrations in patients with impaired or absent TSH responses to TRH is interesting and challenges the concept that free thyroid hormones are the major controlling factors in the feedback control of TSH.     

单纯味觉障碍与丘脑腔隙性脑梗死

目的分析丘脑腔隙性脑梗死与味觉障碍之间的关系。方法对7例主诉味觉障碍的患者进行临床检查、味觉检查及头MRI检查。结果 7例患者味觉检查均表现一侧味觉（甜、咸、酸、苦）消失,头MRI均证实丘脑腹内侧下部有腔隙性梗死灶,病灶位于味觉缺失对侧2例,病灶位于味觉缺失同侧5例。结论 （1）临床上重视单纯性味觉障碍的症状与查体,结合头MRI检查,可以确诊;（2）本文多数病例证实了味觉传导路具有同侧上行的特点,即从孤束核发出的味觉二级纤维在同侧脑干网状结构内上行到达丘脑腹侧后内核小细胞群（VPMpc）;（3）头MRI冠状位的检查异证实VPMpc病变的部位及程度;（4）丘脑腔隙性脑梗死导致的单纯味觉障碍有可恢复性。