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T Thien

Publications and source records attributed to T Thien.

285 records · Page 16Linked to original sources
PubMed1978

[Phaeochromocytomas in neurofibromatosis (author's transl)].

Neurofibromas and phaeochromocytomas derive ultimately from ectodermal tissue. It is therefore not surprising that there is an increase in the incidence of phaeochromocytomas in Recklinghausen's neurofibromatosis. When investigating hypertension in patients with neurofibromatosis one must therefore consider the possibility of a phaeochromocytoma as well as vascular involvement by neurofibromatosis. Two patients with neurofibromatosis and phaeochromocytomas are described.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Effects of coffee on cardiovascular responses to stress: a 14-week controlled trial.

We studied the cardiovascular responses to orthostatic and mental stress of 43 healthy subjects who daily received six cups of boiled or filtered coffee and of 21 healthy subjects who abstained from caffeine-containing beverages. All 64 subjects first received six cups of filtered coffee/day for 2 weeks. Then blood pressure (BP) and heart rate (HR) were recorded before, during, and after a "stand upright" test and a mental arithmetic test. Subjects were then randomized to either complete abstinence from caffeine-containing beverages (n = 21), or consumption of six cups of filtered coffee (n = 21), or consumption of six cups of boiled coffee/day (n = 22). The stress tests were repeated after subjects had been on these regimens for 8 weeks. Abstinence from coffee did not affect the responses of BP or HR to orthostatic stress, or the response of BP to mental stress. The increase in HR caused by mental stress was five beats/min less (p = 0.02) in the no-coffee group than in the filtered- (95% confidence interval -8.8 to -1.2) or boiled- (95% confidence interval -8.4 to -0.8) coffee group. It is concluded that elimination of caffeine decreases the HR response to mental stress.

Adolescent↗
PubMedDate not supplied

Evaluation of two sympathetic cutaneous vasomotor reflexes using laser Doppler fluxmetry.

Disturbances in sympathetic cutaneous vasomotor reflexes may be of pathogenetic importance in several microvascular problems. Laser Doppler fluxmetry (LDF) enables one to study the influence of sympathetic reflexes on skin blood flow. A matter of concern is the high variability of skin blood flow and its reactivity to sympathetic reflex test resulting in a poor reproducibility. In this study we evaluated two sympathetic stimulation tests, distant cooling and inspiratory gasp, and their influence on LDF-measured skin blood flow of the pulp of the big toe in 63 healthy volunteers. No age or sex dependency of the LDF test results was found. Absolute and relative LDF decrease during distant cooling was highly variable between the subjects (LDF decrease, mean +/-SD: 0.7 +/- 5.3%) compared to an LDF decrease of 46.5 +/- 3.1% during an inspiratory gasp test. The reproducibility, however, was better for the distant cooling test [coefficient of variation (CV): distant cooling: 5.8%, inspiratory gasp test: 35.4%]. With the use of a thermostatically controlled LDF probe holder fixed at a temperature of 36 degrees C, the short-term reproducibility of the two sympathetic vasomotor tests did not improve, probably because of a steady increase in baseline skin blood flow during the test. Surprisingly long-term variability of the percentage LDF decrease during the inspiratory gasp test, performed with the heated LDF probe, was lower compared to the short-term variability (CV 19.2 vs. 39.0%, p < 0.05). In conclusion to study sympathetic skin vasomotor reflexes with LDF, vasoconstriction during the inspiratory gasp test was more uniform compared to the distant cooling test, although the latter was more reproducible. Measuring skin blood flow reactivity with a heated LDF probe (36 degrees C) did not improve reproducibility.

Adult↗
PubMedDate not supplied

Skin vasomotor reflexes during inspiratory gasp: standardization by spirometric control does not improve reproducibility.

Arteriovenous anastomoses (AVA) in skin microcirculation are mediated by the sympathetic stimuli. The inspiratory gasp test (IG test) triggers the sympathetic nervous system, resulting in a decrease in AVA skin blood flow, as measured by laser Doppler fluxmetry (LDF). We studied the reproducibility of the IG test under carefully standardized respiratory conditions. In each of 19 healthy (young) volunteers with a mean skin temperature during the experiment above 28 degrees C 13 IG tests were performed, either under spirometric control or uncontrolled and by using a negative pressure transducer. Starting the IG test end-inspiratory results in the most pronounced absolute LDF decrease [140 PU (70-490)], median (minimum-maximum) as compared to starting end-expiratory [100 PU (40-260)] and during inspiration [110 PU (50-350)], respectively, p < 0.001 and p < 0.001. Inspiration as fast as possible results in a larger absolute LDF decrease [150 PU (40-450)], compared to inspiration in 5 s [120 PU (60-340); p < 0.02] and in 10 s [130 PU (40-350); p < 0.05]. Continuously sucking negative mouth pressure results in a larger LDF decrease [140 PU (30-420)] in comparison with taking one deep breath and holding it for 10 s [110 PU (30-270); p < 0.01]. However, standardization of the IG test did not improve its reproducibility.

Adult↗
PubMedDate not supplied

Raynaud's phenomenon: subjective influence of female sex hormones.

Recent studies with standardized laboratory measurements of skin blood flow suggest an influence of female sex hormones on vasospasm. Therefore we evaluated the influence of sex hormonal status on the subjective complaints of Raynaud's phenomenon and furthermore the combined presence of Raynaud's phenomenon and migraine. A detailed questionnaire was filled in by 130 primary Raynaud patients (31 males, 99 females), while 27 females, with regular menstrual cycles without the use of oral contraceptives, kept a diary with daily registration (during three months) of frequency, severity and duration of the vasospastic attacks. Complaints improved during pregnancy in 6 out of 23 females. No influence of the menopause or the use of oral contraceptives was found. An exacerbation in some phases of the menstrual cycle was present in 15 out of 80 females. The diaries, however, did not show such influence of menstrual cycle phase. Migraine was present in 21% of the Raynaud patients. In contrast to most reports in the literature and contrary to the results of laboratory research, this study shows that most females do not experience an important subjective influence of sex hormonal status on vasospastic attacks.

Adult↗
PubMedDate not supplied

Vascular and humoral sympathetic nervous system reactivity during mental arithmetic in primary Raynaud's phenomenon.

To investigate the hypothesis of a sympathetic imbalance in the pathophysiology of digital vasospasms during stress we measured vascular and sympathetic nervous system reactivity during a standardized mental arithmetic test in 12 patients with primary Raynaud's phenomenon in comparison to 12 healthy control subjects. Blood pressure, heart rate, forearm blood flow and fingertip laser Doppler flux were measured together with the venous concentrations of norepinephrine and epinephrine from the back of the hand before and during mental arithmetic in a climate room. No significant differences in circulatory or sympathetic reactivity were found between both groups except for fingertip skin circulation with a small decrease of laser Doppler flux (-11.6%) in controls, whereas it increased in PRP (46.6%; p less than 0.05 between both groups). Baseline skin blood flow was inversely correlated with changes in laser Doppler flux (R = -0.91; p less than 0.001; no. 24) irrespective of the diagnosis when baseline skin bloodflow is low a vasodilatory response occurs and when it is high a vasoconstrictive response is seen. Initial laser Doppler flux was lower while baseline diastolic blood pressure, heart rate and (nor)epinephrine concentrations were significantly higher in Raynaud-patients suggesting an increased sympathetic activity at rest in primary Raynaud's phenomenon.

Adult↗
PubMedDate not supplied

Influence of cold challenge on finger skin temperature during long-term use of beta-adrenoceptor blocking drugs in hypertensive patients.

Because complaints of cold extremities are a frequent side effect of beta-adrenoceptor blocking drugs, we assessed Finger Skin Temperature (FST) during a standardized Finger Cooling Test (FCT) in 51 normals and in 50 hypertensive patients after long term treatment with beta-adrenoceptor blockers. In the 29 hypertensive patients with complaints of cold extremities the recovery of FST after cold challenge was significantly worse as compared to the 21 hypertensive patients without complaints. Hypertensive women who used beta-adrenoceptor blocking agents showed lower FST-values after the cold test in comparison to hypertensive men. No difference in recovery of FST were found between the users of non-selective and selective beta-adrenoceptor blockers. We conclude that the FCT is a suitable method to detect a decreased ability of vasodilate during chronic beta-adrenoceptor blockade in hypertensive patients.

Adolescent↗