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Biomedical subjects

C Sachs

Publications and source records attributed to C Sachs.

At least 91 records · Page 5Linked to original sources
PubMed1984

Inactive renin in infants and children: evidence for its physiological response to orthostasis in children.

The aim of this work was to investigate the presence of inactive renin (IR) in plasma of normal infants and children and nephrectomized children and to study the plasma IR response to stimulation of the renin-angiotensin system (orthostasis) in children. The study was performed in 10 normal infants (2 days to 1 yr old), 28 normal children (1-15 yr old), 8 nephrectomized children (8-14 yr old), and 7 normal adults (20-40 yr old). IR was calculated as the difference in renin activity in trypsin-treated (1500 micrograms/ml) plasma, e.g. total renin (TR), and in untreated plasma, e.g. active renin (AR). IR was not detectable in most infants in the supine position, but their AR values were high (8.8-30 ng/ml X h). Moreover, in some of these infants, trypsin appeared to degrade renin activity, since TR values were lower than AR values. IR was detectable in 3 infants and 27 children, but their AR values were in a lower range (0.3-10 ng/ml X h). Trypsin degradation of renin activity was not found in either children or adults. With increasing age (2 days to 40 yr), AR decreased while IR and the IR to TR ratio increased significantly (P less than 0.001). A significant (P less than 0.001) inverse relationship was found between the IR and AR values of subjects 2 days to 40 yr old. IR was detectable in all nephrectomized children and represented 25% of normal values, while AR was undetectable (less than 0.1 ng/ml X h). In children in the upright position, IR decreased and AR increased significantly (P less than 0.001) in a reciprocal manner. TR did not change. These data suggest 1) that trypsin degradation of renin activity and absence of trypsin-activated IR are specific to infants with high AR levels, and 2) that IR might be activated in vivo into AR, especially after changes in position in children. IR could be a prorenin playing a physiological role in children.

Adolescent↗
PubMed1984

[Beta 2 microglobulin. Index of glomerular filtration in children].

121 assays for plasma Beta 2 microglobulin (B2M) levels were carried out with an immuno-enzymatic technique in 94 children whose ages ranged from 13 months to 18 years and whose renal functions showed various levels of renal impairment. In the 37 children with normal glomerular filtration rate, plasma B2M level was 1.58 +/- 0.48 mg/l (mean +/- 1 SD) and no significant differences were found according to sex, ages or heights. In the 29 children with glomerular filtration rate (GFR) ranging from 20 to 100 ml/min/1.73 m2, there was a significant correlation between B2M and the inulin clearance, plasma creatinine level and creatinine clearance (p less than 0.001). In 28 patients presenting with terminal renal failure, plasma B2M levels were significantly higher in children undergoing hemodialysis than in those under chronic peritoneal dialysis. These results indicate that B2M levels are as good an index of glomerular filtration rate as serum creatinine whereas its assay uses a long and difficult technique.

Adolescent↗
PubMed1983

Postmortem changes in binding to the muscarinic receptor from human cerebral cortex.

The effects of storage at 4 degrees C on the antagonist and agonist binding properties of the muscarinic acetylcholine receptor from fresh surgical and frozen autopsy samples from human cerebral cortex were studied. The number of L-[3H]3-quinuclidinyl benzilate binding sites and their affinities were stable up to 51 h, both when stored as pieces of intact nonfrozen tissue and as a homogenate. The agonist binding properties as measured by the ability of the muscarinic agonist carbachol to compete with L-[3H]3-quinuclidinyl benzilate were also stable up to 51 h when the tissue was stored in the form of pieces. The affinity for carbachol decreased when the tissue was stored as a homogenate. The frozen autopsy samples showed no significant differences in binding properties in comparison with fresh neurosurgical tissue.

Aged↗
PubMed1982

Enzymatic determination of acetate in serum or plasma using a centrifugal fast analyser.

A simple enzymatic spectrophotometric micromethod is described for direct kinetic assay of acetate in serum or plasma using the Eni-Gemsaec centrifugal fast analyser. The method is based on the transformation of acetate and ATP into acetylphosphate and ADP by acetate kinase (EC 2.7.2.1). ADP is further measured by two coupling reactions involving pyruvate kinase (EC 2.7.1.40) and lactate dehydrogenase (EC 1.1.1.27) with measurement of NADH consumption at 340 nm. The method involves a reagent blank for compensation of reagent deterioration, a preincubation of 3 min without acetate kinase to eliminate any interference due to endogenous pyruvate, and a two-point kinetic protocol with measurements of absorbance at 95s and 395 s. The analytical performances of the proposed method were investigated using an evaluation scheme proposed by the French Society of Clinical Biology.

Acetate Kinase↗
PubMed1982

Pre- and postsynaptic muscarinic receptors in surgical samples from human cerebral cortex.

The present study was carried out using fresh surgical material from human cerebral cortex of patients who were not medicated with atropine or other drugs known to affect the cholinergic system. The concentration of [3H]L-quinuclidinyl benzilate binding sites was 0.45 /+- 0.05 pmol/mg protein and the Kd-value of the receptor-[3H]L-QNB-complex was 0.038 /+- 0.005 nM. Agonist binding was studied by varying the concentration of carbamylcholine (10(-8) to 10(-2) M) in the presence of a constant concentration (0.2nM) of [3H]L-quinuclidinyl benzilate. The data revealed the existence of two populations of binding sites for carbamylcholine with different affinities and capacities. Presynaptic muscarinic receptors were studied in slices of the cerebral cortex, which were loaded with [3H]choline. The muscarinic antagonist, atropine (10(-6) and 10(-7) M) acting at the presynaptic muscarinic receptors enhanced the release of [3H] acetylcholine. It was also shown that muscarinic stimulation leads to elevation of cyclic GMP levels in the human cerebral cortical slices.

Acetylcholine↗
PubMed1982

Autonomic regulation of cardiopulmonary functions in sleep apnea syndrome and narcolepsy.

Thirteen patients with sleep apnea syndrome, nine with narcolepsy, and age-matched controls were studied to evaluate possible impairment of autonomic nervous control of cardiovascular and pulmonary function. The sleep apnea group had subnormal increases in heart rate and blood flow in the resting arm upon muscle contraction, although they were higher than seen in the narcolepsy group. Some sleep apnea patients had marked bradycardia in response to a dive reflex test. Other cardiovascular results did not differ from controls. Some sleep apnea patients had low ventilatory response to CO2. One had abnormal spirometry, two had enlarged tonsils, and five were snorers. The narcolepsy group had subnormal heart rate, blood pressure, and forearm blood flow responses to muscle contraction, subnormal respiratory sinus arrhythmia, and subnormal heart rate response to the Valsalva maneuver. Ventilatory function was normal. Thus, narcolepsy is associated with attenuation of some cardiovascular reflexes. The impairment is probably of central origin. The causative factor for the sleep apnea syndrome is probably also in the central nervous system rather than in the pulmonary or upper airway region. Great interindividual variations in the sleep apnea group point to a more multifactorial etiology. Thus, the two conditions of increased sleepiness are associated with autonomic dysfunction, but the differences in autonomic abnormalities reinforce that sleep apnea and narcolepsy, also in this respect, represent different clinical entities.

Adult↗
PubMed1982

Sleep related growth hormone and prolactin secretion in children during constant rate enteral nutrition.

The aim of this study was to investigate the nocturnal secretion of growth hormone and prolactin in a particular model where nutrients are delivered continuously. Six children with severe intestinal diseases undergoing total constant rate enteral nutrition for 1.5 to 8 months have been studied; all children had a normal nutritional status at the time of the recording. Sleep patterns were studied by the usual polygraphic methods from 10 p.m. to 8 a.m. Blood samples were taken every 20 min through an indwelling catheter for growth hormone and prolactin plasma level determination. Several growth hormone peaks were observed with a peak always secreted in connection with stage III-IV of the first cycle. This early peak was significantly higher than the following ones. Nocturnal patterns of prolactin secretion showed individual differences characterized by a series of episodic releases which consisted of a few long rises (4 patients) and several small fluctuations; no correlation was found with the sleep patterns; no increase in the level throughout the night was observed. Loss of the rhythmicity of alimentation does not alter the secretion of growth hormone during sleep.

Adolescent↗
PubMed1982

Clinical experience with the objective symmetry detector method for gammaencephalography.

The objective symmetry detector method for gammaencephalography previously described has been further developed. A rapid micro-computerized automatic measuring device has been constructed and the method used in screening of neurologic patients. The previously chosen classification boundaries between normal and pathologic isotope distributions were not entirely satisfactory for clinical screening of patients with neurologic symptoms. By use of new classification boundaries, 87 per cent of patients with brain tumours could be separated from patients with neurologic symptoms but without gross brain lesions and from neurologically healthy subjects.

Adult↗
PubMed1982

Nyctohemeral rhythm of plasma renin activity and plasma aldosterone in children.

Circadian rhythms of plasma renin activity (PRA) and plasma aldosterone (PA) were studied in eight healthy children, 7 to 15 years old. Blood samples were obtained at 7:00 AM, 10:00 AM, 1:00 PM, 4:00 PM, 5:00 PM, 8.00 PM, and midnight on day 1 and 4:00 AM and 7:00 AM on day 2. Children had normal activity during this test. Intra- and interindividual changes were noted in PRA in plasma taken in the upright position. Mean PRA values for samples taken in the upright position were maximal at 1:00 PM (7 ng/ml/hr) and minimal at 5:00 PM (4.1 ng/ml/hr). Mean PRA in the supine position was maximal at 4:00 AM on day 2 (5.6 ng/ml/hr), and its rise was statistically significant compared with the mean PRA at 7:00 AM on the same day (3.9 ng/ml/hr). Plasma aldosterone varied without any definite pattern. No correlation was found between PRA and PA and 24-hr urinary sodium excretion.

Adolescent↗
PubMed1982

Menstruation-related periodic hypersomnia: a case study with successful treatment.

A 16-year-old girl suffered from 1 to 2-week periods of hypersomnia associated with each menstruation. Serum hormone levels were normal. CSF concentrations of homovanillic acid and 5-hydroxyindolacetic acid were lower in hypersomniac than in symptom-free phases. 3-methoxy-4-hydroxyphenylethylene glycol was not affected. The sleep periods occurred only in connection with ovulatory menstrual cycles. When ovulation was inhibited by a combination of ethinylestradiol and lynestrenol, an oral contraceptive pill, the hypersomnia ceased. Thus, the hypersomnia seemed to be linked to the occurrence of ovulatory menstruations.

Adolescent↗
PubMed1982

Basal ganglia calcifications on CT: relation to hypoparathyroidism.

Eleven of 12 patients with primary hypoparathyroidism had CT evidence of bilateral intracerebral calcifications, mostly within the basal ganglia, but also in other sites. None of the 12 patients with secondary hypoparathyroidism had intracerebral calcifications. Among 20 patients with calcifications discovered incidentally, idiopathic hypoparathyroidism was diagnosed in 2 patients. Four patients had calcifications associated with antiepileptic treatment, parkinsonism, or Kearns-Sayre syndrome. The cause of the calcifications was unknown in 14 patients. No specific neurologic sign was related to the localization of the intracerebral calcifications. Incidentally discovered basal ganglia calcifications should lead to endocrinologic evaluation of parathyroid function. CT examination of the skull may be used to ascertain the diagnosis of idiopathic hypoparathyroidism.

Basal Ganglia Diseases↗
PubMed1981

[Effect of constant rate enteral nutrition on gastrin secretion in children (author's transl)]].

The aim of this work was to study gastrin secretion in children receiving constant rate enteral nutrition (CREN) then avoiding intermittent stimulation induced by meals. Induced hypergastrinemia was performed in 12 children during CREN and compared with that in 8 children with intermittent oral feeding as a control group. Before stimulation by protein load there was no significant difference between the 2 groups; 20 minutes after stimulation, there was no change in the serum gastrin concentration in the CREN group, but a dramatic increase in the control group. The hypothetic role of gastrin and/or intestinal factors is advanced to explain the inhibition of gastrin secretory response during CREN. A progressive substitution from continuous to discontinuous intakes is suggested to avoid weaning complications of this nutritional technique.

Adolescent↗