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Biomedical subjects

A Nicolai

Publications and source records attributed to A Nicolai.

At least 55 records · Page 3Linked to original sources
PubMed1984

Interindividual differences in a set of biological rhythms documented during the high arctic summer (79 degrees N) in three healthy subjects.

The High Arctic summer with its permanent sunlight provides a situation in which one of the natural synchronizers, the light-dark alternation, is minimal. During the summers of 1981 and 1982 three healthy right-handed geographers who were performing field studies in Svalbard as part of their own research volunteered to document, 4-6 times per 24 hr for respectively 63, 141 and 147 days, a set of circadian rhythms: self-rated fatigue, oral temperature, grip strength of both hands, heart rate and times of awakening and retiring. Tests were performed before departure from France, in Svalbard (79 degrees N latitude) where their daily activities were often strenuous, and after returning to France. Time series were treated individually according to three methods: display of data as a function of time, cosinor analyses to quantify rhythm parameters, and spectral analyses to estimate component periods of rhythms. Circadian parameters such as period and acrophase of activity-rest, oral temperature and fatigue rhythms were not altered. On the other hand, the circadian rhythm in grip strength was altered: the period differed from 24 hr in one subject, while grip strength acrophase of the left, but not the right, hand of the other two subjects was phase shifted during the sojourn in Svalbard. A prominent circahemidian (about 12 hr) rhythm was observed in two subjects for their heart rate in Svalbard, while a prominent circadian rhythm (differing from exactly 24 hr) was observed in France associated with a small circahemidian component.

Activity Cycles↗
PubMed1983

Circadian and seasonal changes in ACTH-induced effects in healthy young men.

The effects of the ACTH 1-17 analogue (100 micrograms i.m.) as a function both of time of day (7.00, 14.00 and 21.00 h) and season (winter versus summer) were determined on a set of physiological variables: urinary 17-hydroxycorticosteroids, oral temperature, grip strength (right and left hands), peak expiratory flow and self - rated fatigue. Six young healthy males took part in the study in January-February 1980 and June-July 1981. They were synchronized with a diurnal activity from 7.00 to midnight and a nocturnal rest. Urine was collected every 3 to 4 hours, at fixed clock hours over 72 h (winter) and 48 h (summer). There was a one week interval between each ACTH test or placebo control. Variables were measured according to the same schedule. 24 h urinary 17-OHCS excretion was maximum for ACTH injected at 7.00 in winter and 14.00 in summer, and the minimum occurred after ACTH given at 21.00. The highest peak of urinary 17-OHCS was found after ACTH at 7.00 both in winter and in summer. It is likely that the maximal stimulation of glucocorticoid secretion occurs when ACTH is administered around the beginning of the activity span. Both in winter and summer the injection of ACTH at 7.00 was followed by the greatest decrease in self-rated fatigue (24 h mean) and the largest increase (24 h mean) both in grip strength and peak expiratory flow (bronchial patency) in comparison with other times of ACTH administration (14.00 and 21.00 h).

17-Hydroxycorticosteroids↗
PubMed1983

A case of cheiralgia paresthetica secondary to diabetes mellitus.

The anatomy and etiology of cheiralgia paresthetica are discussed in the light of a case of this syndrome in a diabetic. The variability of the area affected can be ascribed to anatomical variants in the innervation of the hand ("ulnar intervention" in the radical sensory distribution). In patients in whom mechanical causes have been excluded diabetes mellitus should be considered as a possible cause.

Action Potentials↗
PubMed1982

Lateral geniculate unit activity in freely moving rats. I. Relation to behavior and stimulus relevance.

Using semimicroelectrodes implanted in the dorsal lateral geniculate body unit responses to light stimuli were recorded in two groups of rats in the state of water deprivation and after satiation. The animals of one group were trained to keep still in order to receive water, the others were trained to approach water dispenser on the light stimulation with a water reward. Responses of about two thirds of the units recorded in both groups differ depending on the animals’ behavior or motivational state. Drinking before stimulation had little influence. In spite of a similarity of behavior in both groups there was a significant tendency only in the LT-group, consisting of a prolongation of the postexcitatory suppression periods and an increase of the second excitation in satiated animals vs. water deprived ones. This might be ascribed to processes connected with the biological meaning of the light stimulus.

Animals↗
PubMed1982

Lateral geniculate unit activity in freely moving rats. II. Relation to conditioning and motivation.

Unit activity of the lateral geniculate body was recorded on successive days using implanted semimicroelectrodes. Unit responses to light stimuli recorded in water deprived and satiated animals were compared. They differed in dependence on whether the light stimulus is a conditioned one (leading to a behavioral response) or is acting merely as a physical event without relevance to the animal’s adaptive behavior. This was confirmed using the following experimental procedures: (i) recording from one cell population on several successive days under equal conditions, (ii) elaborating a conditioned reflex during recording, and (iii) comparing unit responses to light stimuli in relation to the rat’s behavioral responses (correct, not correct) during the first training days.

Animals↗
PubMed1977

[Responses of single cells of the rat lateral geniculate body to light stimuli differing in wavelength and intensity].

Single unit responses of the rat's lateral geniculate body to red and green stimuli of light emission diods and to daylight spectrum flashes were recorded. The primary response consisted either in an increase or in a decrease of the discharging rate. Each unit was responsive to all light stimuli either with excitation or inhibition, i.e. the direction of the change in the discharging rate was always the same for one cell. When applying the stimuli in the above mentioned sequence we found a shortening of the latency period and a shorter duration of the primary response, more afterdischarges, and a more marked postexcitatory inhibition.

Animals↗
PubMed1975

[Plastic response changes in neurons from lateral geniculate body in rats submitted to conditional reflectory stimulation].

In alert curarized rats the influence of an electric stimulation of the tail skin on the flash-evoked activity of single units of the dorsal part of the lateral geniculate body (CGLd) was investigated. The light flashes were applied 400 msec prior to the electric shocks. 50% of the units showed a change of the response pattern to flash. In the majority of cases the response shifts consisted in a facilitation, which developed gradually and persisted in most of the units examined, even when the electrical stimulus was no longer given in combination with the light. The results are discussed taking into consideration the possibility of an altered emotional or motivational status of the animal, which could play a role in the development of plasticity at the unitary level.

Action Potentials↗
PubMedDate not supplied

Gastric emptying and intragastric balloon in obese patients.

BACKGROUND: Intragastric balloons have been proposed to induce weight loss in obese subjects. The consequences of the balloon on gastric physiology remain poorly studied. We studied the influence of an intragastric balloon on gastric emptying in obese patients. PATIENTS AND METHODS: 12 patients were included in the study, with BMI (mean +/- SD) of 38.51 +/- 4.32 kg/m2. The balloon was inserted under light anaesthesia and endoscopic control, inflated with 700 ml saline, and removed 6 months later. Body weight and gastric emptying (T1/2 and T lag) using 13C-octanoic acid breath test were monitored before balloon placement, during its permanence and 2 months after removal. RESULTS: Mean weight loss was: 6.2 +/- 2.3 kg after one month; 12.4 +/- 5.8 kg after 3 months; 14.4 +/- 6.6 kg after 6 months and 10.1 +/- 4.3 kg two months after BIB removal. Gastric emptying rates were significantly decreased in the first periods with balloon in place, and returned to pre-implantation values after balloon removal. T1/2 was: 87 +/- 32 min before BIB positioning, 181 +/- 91 min after 1 month, 145 +/- 99 min after 3 months, 104 +/- 50 min after 6 months and 90 +/- 43 min 2 months after removal. T lag was 36 +/- 18 min before BIB positioning, 102 +/- 82 min after 1 month, 77 +/- 53 min after 3 months, 59 +/- 28 min after 6 months and 40 +/- 21 min. 2 months after removal. CONCLUSIONS: BIB in obese patients seems to be a good help in following the hypo caloric diet, especially during the first three months when the gastric emptying is slower and the sense of repletion is higher. After this period gastric emptying starts to return to normal and the stomach adapts to BIB loosing efficacy in weight loss.

Adult↗
PubMedDate not supplied

[Femoral neuropathy, diabetes mellitus, reduced glucose tolerance. Possible correlations].

44 cases are reported of definite femoral mononeuropathy, by clinical and neurophysiological criteria. In 11 patients there was diabetes mellitus, in 10 compressions, in 23 no determined etiology was identified. Among these 23 patients, 15 showed glucose intolerance. The value of diabetes mellitus and the glucose intolerance in the etiology of femoral mononeuropathy is discussed.

Adult↗
PubMedDate not supplied

Language disturbances from paramedian thalamic infarcts: a CT method for lesion location.

The authors describe the case of three patients suffering from language disorder secondary to mesencephalo-thalamic infarcts. One of them showed the clinical features of transcortical motor aphasia, while the other two presented the typical pattern of the so-called "thalamic aphasia". The CT-stereotaxic method for lesion localization disclosed that the dorso-medial was the mostly involved thalamic nucleus in each case. Since this nucleus is connected both with Broca's and Wernike's areas, the authors suggest that the more or less extensive involvement of the fibres connecting these structures may be responsible for the different aphasic features presented in these cases.

Aged↗