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Biomedical subjects

M Lindqvist

Publications and source records attributed to M Lindqvist.

At least 55 records · Page 3Linked to original sources
PubMed1992

Brain uptake and release of amino acids in nondiabetic and insulin-dependent diabetic subjects: important role of glutamine release for nitrogen balance.

We measured net uptake and release of amino acids in the brain of 7 nondiabetic and six diabetic subjects. Duration of insulin-dependent diabetes (IDDM) was 19.4 +/- 2.1 years. Arteriojugular vein measurements were performed before and after 120 minutes of insulin infusion and ensuing Biostator-regulated normoglycemia. Cerebral blood flow was measured during normoglycemia by 11-CH3-F and positron emission tomography. During hyperglycemia in the IDDM subjects, arterial concentrations of valine and leucine were higher, and those of glutamic acid and arginine lower, than in nondiabetic subjects. Insulin infusion lowered levels of most amino acids in both groups. Insulin treatment did not significantly affect the uptake or release of amino acids. Significant net uptake of branched-chain amino acids was noted in both groups, as well as uptake of lysine and phenylalanine in the IDDM subjects. The sum of measured differences was not different from zero in either group. Nitrogen balance depended on impressive release of glutamine from the brain (-963 +/- 147 and -960 +/- 303 nmol/100 g/min), which amounted to 73% and 69% of net release in nondiabetic and IDDM subjects, respectively. We conclude that balance between uptake and release of amino acids is similar in nondiabetic and in long-term IDDM subjects.

Adult↗
PubMed1992

Potential differences in the inferior vena cava and between cava and extravascular electrode at leg contraction in man.

When a voluntary adult male contracted his leg muscles, electric potential differences were recorded between platinum electrodes positioned inside the vena cava or between the vena cava and the grounded skin. Two experiments confirm that potential differences at leg contractions in man have a similar appearance as those in the rat at pain-evoked contractions of leg muscles. Platinum electrodes were used in man. The potential differences obtained are thereafter compared with recordings with Ag-AgCl electrodes in salt-bridges in the rat. Slow potential waves with superimposed irregular potential oscillations are recorded in man as previously found in the rat using platinum or Ag-AgCl electrodes. The findings indicate that vascular-interstitial routes participate in a vascular-interstitial-neuromuscular closed circuit, which is activated at contraction of the muscles.

Adult↗
PubMed1990

Positron emission tomographic measurements of cerebral glucose utilization using [1-11C]D-glucose.

Regional CMRglc was measured in seven healthy volunteers with positron emission tomography using [1-11C]D-glucose. Regional CBF was measured using [11C]fluoromethane. The arteriovenous differences of unlabeled glucose and oxygen together with 11C metabolites were also measured. In addition to the loss of [11C]CO2, a loss of acidic 11C metabolites was also detected. A three-compartment model was applied to the tracer data in the time interval 0-24 min. After correction for the loss of 11C metabolites, the tracer method gave an average CMRglc of 26.4 +/- 1.9 (SD) mumol/100 g/min, close to the value obtained with the Fick principle. After correction for the loss of [11C]CO2 only, the tracer method gave 23.6 +/- 2.1 mumol/100 g/min, compatible with (1/6) CMRO2, obtained with the Fick principle. These results and the time course of the loss of acidic 11C metabolites are consistent with the presence of nonoxidative metabolism of glucose that causes an early loss of mainly [11C]lactate after a bolus injection of the tracer. This implies that [1-11C]D-glucose measures the rate of glucose oxidation rather than the total CMRglc. The experiments using [1-11C]D-glucose were compared to five analogous experiments using [U-11C]D-glucose together with [15O]H2O as a flow tracer. After correction for the loss of [11C]CO2, the two glucose tracers gave similar global values of CMRglc and other parameters associated with glucose utilization, but with labeling in the carbon-1 position, the loss of [11C]CO2 was substantially delayed and the contrast between gray and white matter was improved.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1990

Cerebral blood flow and substrate utilization in insulin-treated diabetic subjects.

We compared regional cerebral blood flow (rCBF) and arteriojugular vein differences of glucose, ketones, glycerol, lactate, pyruvate, and O2 in eight subjects with well-controlled insulin-dependent diabetes mellitus (IDDM) and in six healthy volunteers. Duration of diabetes was 19.4 +/- 2.1 yr. Measurements were performed before and after 120 min of insulin infusion and concomitant Biostator-controlled normoglycemia. Net uptake of ketones was seen in IDDM subjects before but not after insulin. Net uptake of glucose did not differ significantly between groups. During normoglycemia the molar ratio of O2 to glucose uptake was lower in IDDM than in nondiabetic subjects (4.68 vs. 5.50; P less than 0.05; Wilcoxon test). Small but significant release of lactate and pyruvate was seen in IDDM but not in nondiabetic subjects. The rCBF was measured by 11CH3F and position emission tomography. Global mean CBF was higher in IDDM subjects (64.9 +/- 5.9 vs. 49.3 +/- 2.7 ml.100 g-1.min-1, means +/- SE in nondiabetic subjects, P less than 0.05). rCBF was enhanced in many cortical and subcortical areas, whereas it was decreased in the head of the caudate nucleus. Neuropsychological testing did not reveal obvious cognitive dysfunction. The results imply that a larger fraction of glucose is nonoxidatively metabolized in the IDDM subjects and furthermore indicate an abnormal rCBF pattern in these subjects.

Acetoacetates↗
PubMed1987

Natural history of postoperative aneurysm rests.

In a series of 715 patients operated on by microsurgical techniques for intracranial saccular aneurysms between 1970 and 1980, part of the aneurysmal sac was not obliterated in 28 aneurysms in 27 patients (3.8% of 715 cases). Clinical follow-up evaluation for 8 years (range 4 to 13 years) and angiographic follow-up studies for 6 years (range 2 to 10 years) in these 27 cases revealed that one aneurysm rest increased in size and bled twice, five were spontaneously obliterated, two decreased in size, 13 remained unchanged, and in seven cases no late follow-up angiography was performed. The incidence of rebleeding from an aneurysm rest was 3.7% of the 27 in whom the sac was not obliterated and 0.14% of all 715 patients who were operated on.

Adult↗
PubMed1986

Accuracy of computed tomography in the diagnosis of herpes simplex encephalitis.

The accuracy of computed tomography (CT) in the diagnosis of herpes simplex encephalitis (HSE) was assessed in 121 patients who during a 2 1/2 year period entered a prospective Swedish joint study with participation of six University Centres. The patients presented with symptoms and signs of febrile focal encephalopathy. The age ranged from 1 month to 76 years (mean 37.3 years). Only 6 were infants less than one year old. HSE was diagnosed in 50 patients by the demonstration of intrathecal HSV antibody production and/or by HSV isolation or antigen detection in brain tissue specimens. A total of 308 CT examinations--the majority performed during the first 5 days after onset of CNS symptoms--were evaluated under blind conditions. The correct diagnosis of HSE was usually suggested within 5 days after onset of neurologic symptoms yielding a sensitivity of 0.73 and a specificity of 0.89. Predominant location of the HSE lesions was the temporal lobes (88%), which rarely were involved in the non-HSE group (11%). Haemorrhage was a rare finding (12% ) and enhancement after intravenous contrast administration was insignificant. Repeat examinations further increased accuracy. It is concluded that the good reliability of high resolution CT, further improvement of immunologic techniques and the advent of new atoxic antiviral drugs all are factors which may in the future obviate the need for brain biopsy.

Adolescent↗
PubMed1986

Stereotactic radiation therapy of intracranial arteriovenous malformations.

Twenty-six patients with large intracranial arteriovenous malformations (AVM), not suited for open surgery or radiosurgery, have been treated by fractionated stereotactic radiation therapy using a linear accelerator. The preliminary results are based on follow-up angiography one and a half years after treatment, and in 5 cases also 5 years after treatment. In 2 cases a complete obliteration of the AVMs has occurred, and in the majority of the remaining cases a reduction of the size of the lesion has been obtained. Further development of the method is needed in order to improve the results. Today treatment with this technique is only recommended in cases which cannot be treated with other methods.

Adolescent↗
PubMed1982

Diagnosis of herpes simplex encephalitis. A comparison between electroencephalography and computed tomography findings.

In a series of six cases of encephalitis caused by herpes simplex virus, type 1, the diagnostic and prognostic value of the electroencephalogram (EEG) was investigated. Special interest was focused on the time relationship between the appearance of abnormal EEG findings, the initial clinical symptoms and the changes in cranial computed tomography (CT). The characteristic periodic EEG pattern can be demonstrated within 2 days of disease, before typical structural changes appear in CT. A unilateral periodic pattern may be associated with a good prognosis, whereas all patients with bilateral changes died in spite of specific antiviral therapy.

Adult↗
PubMed1981

Diaphanoscopy and diaphanography for breast cancer detection in clinical practice.

Transillumination of the female breast has during the past few years been reintroduced as an aid in the diagnosis of breast lesions. A series of 259 women with symptoms from the breast were examined by mammography, clinical examination by two independent surgeons, diaphanoscopy by one of the surgeons, diaphanography, and fine needle aspiration biopsy of material taken from palpable tumours. The results were evaluated in order to ascertain the contribution made by transillumination procedures to the diagnosis of malignancy. Carcinoma of the breast was confirmed in 26 women. The malignancy was correctly suggested in 21 and 23 women, respectively, at clinical examination, in 19 by mammography, in 20 by diaphanoscopy, in 16 by diaphanography and in 20 by aspiration cytology. The number of false positive cases was high, especially with the transillumination procedures. All malignancies detected by diaphanoscopy were also believed to be carcinoma at the clinical examination. The three cancers falsely classified as benign at clinical examination were correctly identified as malignant only by mammography or cytology or both.

Adult↗
PubMed1980

Cisternal abnormalities produced by clinical tumours in the posterior cranial fossa. I. Cerebellar tumours.

A detailed analysis of the deformities of the subarachnoid cisterns was carried out in a clinical material of 65 cases with cerebellar tumours examined by encephalography. The distortion of the cisterns was related to 8 different tumour positions, and the results compared with those from a previous experimental investigation. Typical cisternal distortions for cerebellar tumours are listed, constituting a basis for a general analysis of the cisternal abnormalities demonstrated by whatever means of neuroradiologic procedure employed: pneumography, computer tomography or cisternography with positive contrast medium.

Adolescent↗
PubMed1980

Computer tomography in the evaluation of subarachnoid hemorrhage.

Repeat CT scanning and cerebral angiography has been performed in 68 consecutive patients with subarachnoid hemorrhage. Blood in the subarachnoid cisterns could be discerned in 27 of 32 patients provided the examination was performed within 2 days of the bleeding. The distribution of cisternal blood can be identified which, in combination with the localization of a possible intracerebral hematoma, yields a rather good predictability as to the site of the ruptured aneurysm. The subsequent angiography can thus be directed to the relevant vessel in most cases. Repeat CT scanning can replace angiography in the evaluation of patients with deterioration of the clinical condition.

Adult↗
PubMed1980

Cisternal abnormalities produced by clinical tumours in the posterior cranial fossa. III. Tumours of the brain stem and pontine angle.

The pneumographic appearances of the subarachnoid cisterns have been analysed in detail in a clinical series of 17 patients with brain stem tumours and in 40 with pontine angle tumours. The cisternal distortions may be used to distinguish tumours in the pons from tumours in the medulla oblongata and also to distinguish tumours of the pontine angle with different modes of growth, e.g. tumours mainly indenting the cerebellar hemisphere from those mainly indenting the brain stem. The results should be applicable also for an analysis of cisternal pathology by other methods such as computer tomography and cisternography with positive contrast media.

Adolescent↗