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Biomedical subjects

A Meier

Publications and source records attributed to A Meier.

At least 73 records · Page 4Linked to original sources
PubMed1990

[Pain in the side].

In a 54-year-old patient who entered the hospital because of flank pain of the left side, a prevesicular urethral calculus was found. On further investigation hypercalcaemia and hypophosphataemia were detected, possibly indicating hyperparathyroidism. When an ultrasound of the abdomen was made to exclude hydronephrosis, a tumor in the pancreas was found. The result of the fine needle biopsy of this tumor showed a neuroendocrine tumor. The examination of neuroendocrine parameters was without any reference to an active secreting process. On suspicion of a multiple endocrine neoplasia, a MRI of the hypophysis was made which showed no adenomatous alterations. The examination of the neuroendocrine parameters were without any reference to an active secreting process of the hypophysis, too.

Humans↗
PubMed1989

[Neurological gait changes in old age: basic principles, senile gait].

Gait abnormalities and falls often occur in the elderly, and it is often difficult for the practitioner to distinguish between a specific disease causing disordered gait and gradual changes due to "normal" involution. Based on the biomechanics and the neural control mechanisms of normal adult gait, characteristics of the "senile gait" are described. The senile gait abnormality is regarded as a clinical entity ascribed to age alone and its many cerebellar, extrapyramidal and cerebrofrontal changes, all of which may give rise to disordered central programming of upright stance and gait. The need for a careful evaluation of the elderly patient's station and gait is stressed.

Aged↗
PubMed1988

Conservative replacement of methionine by norleucine in Escherichia coli adenylate kinase.

Escherichia coli grown in limited methionine and excess norleucine media accumulate cyanogen bromide-resistant species of proteins after the methionine supply is exhausted. Bacteria, transformed by recombinant plasmid pIPD37 carrying the adk gene and grown under limiting methionine and excess norleucine, synthesize 16-20% of adenylate kinase molecules having all 6 methionine residues replaced by norleucine. Species showing only partial replacement of methionine residues by norleucine are identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after cyanogen bromide treatment of pure enzyme. Norleucine-substituted adenylate kinase shows structural and catalytic properties similar to the wild-type protein as indicated by circular dichroism spectroscopy and kinetic experiments but exhibits a much higher resistance to hydrogen peroxide inactivation under denaturing conditions.

Adenosine Monophosphate↗
PubMed1987

Comparative diagnostic value of a new computerized vectorcardiographic method (cardiogoniometry) and other noninvasive tests in medically treated patients with chest pain.

The diagnostic value of cardiogoniometry (CGM), a new computerized vectorcardiographic method, for the identification of coronary artery disease was compared with other noninvasive tests in 48 medically treated patients with chest pain. Coronary angiography revealed one-vessel disease in 18, two- or three-vessel disease in 21, and normal coronary arteries in 9 patients. Cardiogoniometry was less sensitive (63%) than thallium-201 (201T1) scanning (82%), but slightly more sensitive than the exercise ECG (50%) or a recently proposed parameter of exercise performance (50%). On the other hand, specificity was comparable among these tests (exercise ECG 78%, thallium-201 scanning 72%, CGM 67%, new parameter of exercise performance 66%). Moreover, the false negative rate of noninvasive testing was reduced from 8 to 3% when CGM was added to thallium-201 scanning and exercise ECG. Our findings indicate that in view of the easier feasibility with computerized technology, the future role of vectorcardiographic methods such as CGM in the noninvasive diagnosis of coronary artery disease should be redefined.

Adult↗
PubMed1987

[Cervix and tocography screening in basic pregnancy monitoring].

Report about a myometrial contractility-screening in 2462 asymptomatic pregnancies at 30 weeks of gestation. A cervical examination was performed in the 26th and 33th weeks of gestation. An increased uterine contraction frequency was obtained in 3% and a cervical opening in 5.6%. Uterine contractions with cervical opening are a high-risk factor of prematurity (52%-70%) whereas uterine contractions alone are of low-risk. The prevention of preterm birth is useful. We found a significant decrease of early neonatal mortality in 487 singleton preterm deliveries after treatment. A classification of unexplained preterm delivery, iatrogenic or elective preterm delivery and complicated preterm labor is recommended for controlled outpatient and clinical trials.

Female↗
PubMed1983

Antihypertensive mechanism of diuretic treatment with chlorthalidone. Complementary roles of sympathetic axis and sodium.

Twenty-three patients with untreated mild to moderate essential hypertension had on the average an abnormally increased cardiovascular pressor responsiveness to exogenous norepinephrine (NE), while plasma and urinary NE, exchangeable body sodium and blood volume were normal. An increased pressor responsiveness to angiotensin II in these patients was associated with a tendency for low plasma renin activity (PRA). Compared to placebo conditions, treatment with chlorthalidone, 100 mg/day, for 6 weeks significantly decreased blood pressure and exchangeable sodium in these hypertensive patients but not in ten normal subjects; blood volume and heart rate were unchanged in both groups. Chlorthalidone induced a marked increase in PRA, but only a mild increase in angiotensin II pressor dose. In contrast, the diuretic caused a greater increase in NE pressor dose than in plasma NE in the hypertensive group, thus improving the disturbed relationship between plasma NE and NE responsiveness in these patients. No significant modification of plasma NE and NE responsiveness occurred in diuretic-treated normal subjects. In addition to sodium and the renin-angiotensin system, the sympathetic regulatory axis seems to be involved in the antihypertensive mechanism of chlorthalidone. Thiazide-like diuretics may decrease blood pressure in essential hypertension in part by lowering an abnormally high cardiovascular NE responsiveness without causing an equivalent increase in circulating NE.

Adult↗
PubMed1983

Correction of altered noradrenaline reactivity in essential hypertension by indapamide.

Fourteen patients with untreated mild to moderate essential hypertension had, on average, an abnormally high cardiovascular reactivity to exogenous noradrenaline and angiotensin II, while plasma noradrenaline, renin activity, exchangeable body sodium, and blood volume were normal. Treatment with a low dose of indapamide (2.5 mg/day) for 6 weeks decreased blood pressure by 10% in these hypertensive patients but not in 13 normal control subjects. Plasma or blood volume and exchangeable sodium were not changed significantly; nevertheless, the latter, and body weight, tended to be decreased slightly. Though a mild reduction in extracellular sodium in both normal and hypertensive subjects appears possible, it may not fully explain per se the blood pressure-lowering effect of indapamide in essential hypertension. Indapamide induced a mild decrease in angiotensin II pressor responsiveness in normal or hypertensive subjects, but a possible depressor influence from this change was probably antagonized by a concomitant pronounced increase in plasma renin activity. In hypertensive patients, the abnormally high noradrenaline reactivity was corrected by indapamide without an accompanying increase in endogenous plasma noradrenaline levels. Indapamide-induced changes in blood pressure correlated with those in noradrenaline pressor dose. It was concluded, therefore, that indapamide may decrease blood pressure in essential hypertension at least in part by lowering an abnormally high cardiovascular noradrenaline reactivity without causing an equivalent increase in adrenergic nervous activity.

Adolescent↗
PubMed1982

Effects of tyramine on blood pressure and plasma catecholamines in normal and hypertensive subjects.

Responses of blood pressure and plasma catecholamines to intravenous injection of tyramine at increasing dosage (30, 45, and 60 microgram/kg, respectively) were evaluated in 25 normal subjects and 20 patients with mild essential hypertension. Basal plasma norepinephrine and epinephrine concentrations before tyramine injections were similar in the two groups. Following tyramine injection, plasma epinephrine was unchanged. Responses of plasma catecholamines and blood pressure to tyramine were similar in the two groups. Plasma norepinephrine increased significantly 2 min after a dose of 30 microgram/kg, but higher tyramine doses failed to produce a further increase in plasma norepinephrine. In contrast, pressor responses to tyramine were dose-dependent. Maximal pressor responses were observed within 23 min after injection. These findings reveal a dissociation between changes in blood pressure and plasma norepinephrine following injection of tyramine. Lack of steady state may limit the value of tyramine bolus injections as a tool for the quantitation of pressor responsiveness to variations in endogenous sympathetic output. Alternatively, it is possible that the pressor effect of tyramine may be mediated at least in part by a norepinephrine independent mechanism.

Adult↗
PubMed1982

Responses of catecholamines and blood pressure to beta-blockade in diuretic-treated patients with essential hypertension.

Twenty patients (mean age 49 +/- 4 (SEM) yr) with mild to moderate essential hypertension were studied during placebo conditions, following 6 weeks of chlorthalidone monotherapy and 6 to 28 weeks of combined beta-blocker-chlorthalidone treatment, or vice versa. Compared to chlorthalidone therapy alone, addition of a beta-blocker to this diuretic caused a further blood pressure reduction in 11 patients (Responders); in 9 patients addition of a beta-blocking agent failed to further reduce blood pressure (Non-responders). Supine and upright plasma renin, aldosterone, norepinephrine and epinephrine levels and catecholamine excretion rates were always comparable between Responders and Non-responders. In both groups plasma and urinary norepinephrine or epinephrine values were not significantly altered following addition of a beta-blocker; heart rate and plasma renin activity were decreased in both groups to a similar extent. It is concluded that the antihypertensive mechanism of beta-blockers given to diuretic treated patients with essential hypertension is independant of renin and not associated with changes in plasma or urinary catecholamines.

Adrenergic beta-Antagonists↗
PubMed1982

Reversal or prevention of diuretic-induced alterations in serum lipoproteins with betablockers.

In 18 patients with essential hypertension serum low density lipoprotein cholesterol (LDL-C) was significantly (P less than 0.001) increased following short-term chlorthalidone therapy, but not during combination therapy with chlorthalidone and a betablocker. This tendency was similar in two subgroups which were studied with an inverse sequence of drug administration. In Group I (11 men), a 22% increase (P less than 0.01) in LDL-C during chlorthalidone monotherapy was restored to normal 6 weeks after addition to a betablocker to the diuretic; in Group II (5 men, 2 postmenopausal women) LDL-C levels were increased by 41% (P less than 0.05) 6 weeks after withdrawal of the betablocker from the combination therapy. No significant changes occurred during either the treatment phase in high density lipoprotein cholesterol or apoprotein B levels. It is concluded that combination therapy with a betablocker may prevent or reverse an increase in serum LDL-C associated with short-term chlorthalidone monotherapy.

Adolescent↗
PubMed1982

Catecholamines, sodium and renin in unilateral renal hypertension in man.

The relative roles of plasma or urinary norepinephrine (NE) and epinephrine (E), exchangeable sodium, blood volume, and plasma renin (PRA) or aldosterone in the pathogenesis of unilateral renal hypertension was evaluated. 99 normal subjects and 33 age-matched untreated hypertensive patients with unilateral renal parenchymal disease (RPD) (n = 18) or unilateral renal artery stenosis (RAS) (n = 15) were compared. Measurements were repeated following operative treatment in 23 patients. Plasma and urinary NE or E, exchangeable sodium and blood volume did not differ significantly between normal and untreated subjects with RPD or RAS. Both patient subgroups had increased blood pressure and supine PRA (p less than 0.001); these abnormalities were milder with RPD. Plasma aldosterone and upright PRA were significantly elevated (p less than 0.05) in RAS only. Operative treatment of RPD and RAS caused decreases in blood pressure (-18 and -28%) and PRA; they correlated in RPD (r = 0.56; p less than 0.05). In RPD and RAS, exchangeable sodium, blood volume, and NE or E values were not significantly changed following operation, except for mildly increased upright PNE in RAS. These observations suggest that the sympathetic system plays no major role in the maintenance of unilateral renal hypertension in man. However, the 'normal' body sodium-volume state in RPD or RAS may be inappropriate relative to coexisting hypertension. In addition to its established role in RAS, mild activation of the renin-angiotensin system may also be important for the pathogenesis of hypertension caused by unilateral RPD.

Adult↗