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Biomedical subjects

J Ekstedt

Publications and source records attributed to J Ekstedt.

At least 37 records · Page 2Linked to original sources
PubMed1990

Community-based study of neurological disorders in Ethiopia: development of a screening instrument.

This paper describes the development of a screening instrument for a community-based neuroepidemiological survey in a rural community in Ethiopia. A pilot study in 1984 to pre-test the questionnaires developed revealed that epilepsy, poliomyelitis, mental retardation and speech disturbances were the most common neurological disorders among the 3,000 rural inhabitants surveyed. The study suggested that a base-population of about 50,000 was required for a future major epidemiological survey to identify rare neurological disorders.

Adolescent↗
PubMed1986

Cerebrospinal fluid hydrodynamic studies in children.

CSF-hydrodynamic investigation using the constant pressure infusion method was used in children. The CSF resting pressure was recorded and the CSF formation rate was measured. The conductance of the CSF outflow pathways and the pressure in the sagittal sinus were calculated. The method was used in children with suspicion of disturbed CSF hydrodynamics due to various neurological and other conditions. The method is applicable in paediatric neurological diagnostics and provides information for further understanding of the mechanisms behind cranial hypertension. The following mean values are offered as reference values in clinical work and in further research in this field: CSF-resting pressure 1.3 kPa, sagittal sinus pressure 1.1 kPa, pressure difference across arachnoid villi 0.5 kPa, conductance of CSF outflow pathways 22.6 mm3 kPa-1s-1, CSF formation rate 6.8 m3s-1.

Adolescent↗
PubMed1984

Effect of cranioplasty on cerebrospinal fluid hydrodynamics in patients with the syndrome of the trephined.

Forty patients with cranial bone defects after craniectomy underwent extensive cerebrospinal fluid (CSF) hydrodynamic investigations by means of a CSF infusion test before and after cranioplasty. The results of these investigations were related to the clinical signs of the patients before and after cranioplasty and to the size and location of the skull bone defect. Twenty-two patients were considered to have "the syndrome of the trephined" (ST). The remaining patients were either free of symptoms or had symptoms not related to ST. CSF hydrodynamic variables that were changed before and normalized after cranioplasty include the following: Resting pressure, sagittal sinus pressure, buffer volume, elastance at resting pressure and pulse variations at resting pressure. The changes were statistically significant mainly in ST patients who were also relieved of their symptoms after cranioplasty.

Adult↗
PubMed1983

Dose regimen of deprenyl (selegiline) and platelet MAO activities.

The effect of various doses of deprenyl on thrombocyte MAO activity in parkinsonian patients has been studied. It is suggested that individual differences in the degree of inhibition are due to differences in the metabolic rate of deprenyl. The recovery of thrombocyte MAO activity was linear at a rate of approximately 10% per day. The linearity of the recovery suggests that the disappearance of the population of thrombocytes is selected with respect to age.

Blood Platelets↗
PubMed1983

Volume/pressure relationship of the cerebrospinal space in humans.

Using constant flow rate infusions and compensating for the fluid formed and eliminated, the net volume/pressure (V/p) relationship of the cerebrospinal fluid (CSF) space in humans was investigated in more than 200 patients. Of these, 16 patients constitute a normal reference material. Reference values for the variables characterizing the V/p relationship are reported. The V/p relationship was found to be nonexponential, which is not consistent with the pressure-volume index theory. The reactivity of the vascular bed during induced CSF volume changes had to be taken into account when analyzing the results. There were reasons to believe that the major volume changes during the recording of the V/p relationship took place in the spinal part of the CSF space and that the pressure of minimal elastance corresponded to the spinal epidural venous pressure.

Adult↗
PubMed1979

Determination of prostaglandin F2 alpha, E2, D2 and 6-keto-F1 alpha in human cerebrospinal fluid.

Prostaglandin (PG)F2 alpha, E2, D2 and 6-keto-F1 ALha were determined in human cerebrospinal fluid by a mass spectrometric technique. The samples were obtained from 12 patients with suspected intracranial disease. A 64 fold variation in PG levels was observed. The major PG was 6-keto-F1 alpha (0.12--15 ng/ml). PGF2 alpha and PGE2 were present in lower concentrations PGD2 was below the level of detection (0.05 ng/ml) except in one patient with extremely high total levels of PGs.

Adult↗
PubMed1978

CSF hydrodynamic studies in man. 2 . Normal hydrodynamic variables related to CSF pressure and flow.

With the patient in the supine position, the subarachnoidal space was infused with artificial CSF at several constant pressure levels. The resulting flow of liquid was recorded. By draining CSF at a low pressure the CSF production rate was determined. Normal values are given and discussed for (1) the resting pressure, (2) the conductance of the CSF outflow pathways, (3) the formation rate of CSF, (4) the pressure difference across the CSF outflow pathways, and (5) the sagittal sinus pressure. None of the variables showed any age dependence, nor was there any sex difference.

Adolescent↗
PubMed1977

CSF hydrodynamic studies in man. 1. Method of constant pressure CSF infusion.

The constant pressure method for the study of the hydrodynamics of CSF is presented. By infusing artificial CSF at constant pressures and recording the resultant flow, it is possible to obtain information about the hydrodynamic conductance of the CSF outflow pathways. By lowering the infusion pressure below the pressure of the sagittal sinus all CSF produced can be collected and the CSF formation rate may thus be calculated. There is a rectilinear relationship between CSF pressure and the flow necessary to maintain the pressure. It is thus concluded that the arachnoidal villi, when once opened, are not further distended by pressure. This method makes possible indirect calculation of the pressure of the sagittal sinus and the pressure difference between the subarachnoid space and the sagittal sinus.

Adolescent↗
PubMed1975

Concentration gradients of monoamine metabolites in human cerebrospinal fluid.

The monamine metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), vanillylmandelic acid (VMA), and 4-hydroxy-3-methoxyphenylglycol (HMPG) were analysed in CSF from different regions of the CSF system to study the caudocranial concentration gradient of the metabolites. Four consecutive 10 ml fractions of CSF were withdrawn in 17 patients during the course of four minutes. The CSF pressure was monitored through a lumbar cannula because of suspected adult hydrocephalus. A pronounced gradient of the HVA concentration was found with a ratio between the last and the first fraction of 1,7. 5-HIAA showed a slight increase while HMPG and VMA showed no increase at higher levels of the CSF system. The results suggest that lumbar HVA reflects dopaminergic activity in the brain, whereas lumbar 5-HIAA and HMPG/VMA reflect the activity of 5-hydroxytryptamine and noradrenaline secreting neurones in both the brain and the spinal cord.

Adult↗
PubMed1975

Measurement of intracardiac pressure through a valve-tipped catheter. Technical note.

Intracardiac pressure recording is a simple and effective way of obtaining optimal placement of the cardiac catheter during shunting procedures. We have also found this method applicable when using a catheter with a slit in its tip. Pressure waves can be accurately recorded by means of a constant rate liquid flow through the catheter.

Cardiac Catheterization↗
PubMed1974

Calculation of the electromyographic jitter.

The electromyographic jitter is the variability at consecutive discharges in the time interval between two action potentials from two muscle fibres from the same motor unit. This paper deals with different methods of expressing the jitter. The method of choice seems to be Mean Consecutive Difference (MCD)[FORMULA: see text]where D(1), D(2) etc. are the individual time interval measurement data and n the number of discharges, preferably 50 or, if the jitter is not changing, 200. MCD can also be estimated from other measures of the jitter like Mean Range of Two (MR(2)) (giving the same estimated value as MCD), Mean Range of Five (MR(5)), Mean Range of Ten (MR(10)) and also from the Standard Deviation (SD). In a distribution without trends the following relations hold:MCD = 1·13×SDMCD = 0·49×MR(5)MCD = 0·37×MR(10)·The presence of slow variations and trends in most recordings makes SD not well suited for calculation because of the risk of getting too high estimates of the jitter.

Action Potentials↗
PubMed1974

Neuromuscular transmission in myasthenia gravis studied with single fibre electromyography.

Patients with myasthenia gravis have been investigated with single fibre electromyography. In all myasthenic muscles recordings were obtained where there was an increase of the jitter and occasional blocking of different degree of single fibre action potentials. The jitter is the variability at consecutive discharges in the time interval between action potentials from two muscle fibres from the same motor unit. During prolonged activity the jitter increased and blockings occurred more and more frequently. The size of the jitter and the degree of blocking also depended on the discharge rate. At a low rate the jitter was lower and the degree of blocking less than at the high rate. Injection of edrophonium could decrease or increase the jitter or leave it unaffected. Single fibre electromyography is a sensitive way of studying the transmission in individual motor end-plates in myasthenia gravis and is also a valuable diagnostic aid.

Action Potentials↗