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Biomedical subjects

K Rootwelt

Publications and source records attributed to K Rootwelt.

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

Cerebral vasoreactivity and blood flow before and 3 months after carotid endarterectomy.

We measured regional cerebral blood flow and cerebral vasoreactivity before and 3 months after carotid endarterectomy using xenon-133 inhalation with single-photon emission computed tomography and the acetazolamide test in 14 selected patients who had suffered cerebral transient ischemic attacks due to an ipsilateral internal carotid artery stenosis. The patients had neither clinical nor cerebral computed tomographic evidence of infarction. Baseline regional cerebral blood flow was symmetrical before and unchanged after endarterectomy. Before endarterectomy, vasoreactivity in the middle and anterior cerebral artery territories of the symptomatic side was significantly reduced (p less than 0.05); however, vasoreactivity was normalized 3 months after surgery. Our findings strongly suggest that the stenoses caused a reduction in perfusion reserve that was improved by carotid endarterectomy.

Acetazolamide↗
PubMed1989

Blood velocity and regional blood flow in defined cerebral artery systems.

Cerebral artery blood velocity and regional blood flow (rCBF) were investigated in 17 normal subjects. Blood velocity was measured with 2 MHz pulsed Doppler ultrasound in the proximal segments of the middle, anterior and posterior cerebral artery (MCA, ACA, and PCA) and in the distal extracranial internal carotid artery (ICA). The rCBF in the regions of interest tentatively corresponding to the perfusion territories of these vessels was estimated using 133Xe inhalation and a rapidly rotating single photon emission computer tomograph. Concomitant capnograph recordings showed that the end-expiratory pCO2 was higher during the rCBF than during the blood velocity examinations. This differences was highly significant. While there was no significant correlation between blood velocity and rCBF when these clear differences in pCO2 were disregarded, we did find significant positive correlations when the data were normalized to a standard pCO2 (5.3 kPa) using accepted formulas. The best correlation was found for the MCA (r = 0.630, p less than 0.001) and the PCA (r = 0.73, p less than 0.001), with a lower correlation in the ACA (r = 0.49, p less than 0.01) and the ICA (r = 0.41, p less than 0.05). The estimated blood velocity (V) given rCBF = 0 was not significantly different from 0. The results support the validity of expressing the relationship between blood velocity (V) and rCBF in defined cerebral artery systems as: V = 1/60 (rCBF) T (A)-1, where A represents the area of the lumen of the vessel segment where the velocity is being measured, and T denotes the size of the brain region being perfused from this artery.

Adult↗
PubMed1989

Effect of acetazolamide on cerebral artery blood velocity and regional cerebral blood flow in normal subjects.

The effect of intravenous acetazolamide 1 g on cerebral artery blood velocity and regional blood flow (rCBF) was investigated in eight normal subjects. Blood velocity was measured with 2 MHz pulsed Doppler in the proximal segments of the middle, anterior and posterior cerebral artery (MCA, ACA, and PCA) and in the distal extracranial internal carotid artery (ICA). The rCBF in the regions of interest tentatively corresponding to the perfusion territories of these vessels was estimated using 133Xe inhalation and a rapidly rotating single photon emission computer tomograph. Both blood velocity and rCBF increased after acetazolamide. There was no significant difference between the percentage ICA blood velocity increase (22 +/- 12%) and the percentage rCBF increase in the ICA region of interest (25 +/- 9%). In the MCA, ACA, and PCA, however, blood velocity increased more (mean increase 36-42%) than the rCBF in the corresponding regions of interest (mean increase 24-26%). These differences were highly significant suggesting a direct and site specific effect of acetazolamide in narrowing the lumen of the proximal MCA, ACA, and PCA, but not of the extracranial ICA. We also propose that the effect of acetazolamide induces reciprocal changes in the extent of adjacent perfusion territories in individual brain hemispheres. Data compiled from all subjects investigated at two very different perfusion levels (before and after acetazolamide) revealed a significant positive correlation between blood velocity and rCBF.

Acetazolamide↗
PubMed1989

Renal effects of trimethoprim in ciclosporin- and azathioprine-treated kidney-allografted patients.

Sixteen stable renal transplant patients on chronic ciclosporin (CS, n = 8) or azathioprine (AZA, n = 8) treatment were given trimethoprim (TMP) 160 mg twice a day for 7 days. This TMP dose did not affect glomerular filtration, as 99mTc-DTPA clearance was unchanged in both groups. TMP did, however, increase serum creatinine and reduce creatinine clearance in all patients. This effect was most pronounced in CS-treated patients. We conclude that even at the moderate dosage, as employed presently, TMP blocks tubular secretion of creatinine. This route for creatinine excretion is quite important as the clearance ratio between creatinine and DTPA averaged 1.21 in CS-treated patients and 1.05 in AZA-treated patients before TMP treatment. During TMP the ratio was reduced to 0.95 and 0.99, respectively, suggesting a complete cessation of tubular creatinine secretion by TMP. TMP did not, however, significantly affect other markers of renal tubular function.

Adult↗
PubMed1989

Effect of nitroglycerin on cerebral circulation measured by transcranial Doppler and SPECT.

We used a combination of transcranial Doppler ultrasonography and single-photon emission computed tomography to noninvasively assess changes in the diameter of the middle cerebral artery induced by sublingual nitroglycerin in 10 healthy subjects. Nitroglycerin reduced mean blood flow velocities without concurrently changing regional cerebral blood flow in the perfusion territory of this vessel. Our results strongly suggest that nitroglycerin causes vasodilatation of the basal intracranial arteries.

Adult↗
PubMed1989

Encircling endocardial ventriculotomy for malignant ventricular arrhythmias. Effect on cardiac performance.

Cardiac performance and hemodynamics were studied with radionuclide ventriculography in 19 survivors of aneurysmectomy and encircling endocardial ventriculotomy for recurrent, sustained ventricular arrhythmia (group I). To characterize the effect of the ventriculotomy on cardiac function, comparisons were made with a similar group of patients who underwent aneurysm surgery for angina pectoris and/or congestive heart failure (group II). Functional classification revealed no difference between the groups and they achieved the same level of exercise after surgery. No intergroup difference was found postoperatively with respect to right or left ventricular ejection fraction, regional ejection fractions, peak ejection rate, cardiac index or stroke volume. Peak filling rate was also similar, as were cardiac volumes. Exercise did not change any parameter of this intergroup similarity. The authors conclude that most patients with moderately impaired left ventricular function who undergo left ventricular aneurysmectomy with encircling endocardial ventriculotomy do not differ in postoperative hemodynamics and systolic or diastolic function from those treated with simple aneurysmectomy.

Adult↗
PubMed1988

Neurological examination, computerized tomography, cerebral blood flow and neuropsychological examination in workers with long-term exposure to carbon disulfide.

Sixteen males, formerly exposed to carbon disulfide (CS2) for at least 10 years (mean 20 years), were administered a neurological examination, cerebral computerized tomography (CT), regional cerebral blood flow (rCBF) examination and neuropsychological examination. The clinical neurological examination revealed abnormalities in 15; cerebral CT showed signs of atrophy in 13; and neuropsychological examination indicated brain organic changes in 13. With the rCBF examination, slight abnormalities were found in 8. The findings indicate that long-term exposure to CS2 involves a risk of developing toxic encephalopathy, demonstrable on both neurological and neuropsychological examination. Furthermore, structural changes in the brain may be demonstrable by cerebral CT.

Brain↗
PubMed1988

Impairment in right ventricular performance after left ventricular aneurysm surgery.

To study the effect of operation for left ventricular (LV) aneurysm on right ventricular (RV) performance, we studied 50 patients before operation with right heart catheterization, RV angiography, and radionuclide ventriculography. Forty patients were followed up and underwent the same investigations 10 +/- 4 months after operation. At baseline, regional RV dysfunction was observed in 89% of the patients whereas global RV dysfunction was present in approximately a third. After operation, no changes in RV regional dysfunction or RV pressures were observed. However, a significant increase in RV end-diastolic (p less than 0.03) and end-systolic volume indices (p less than 0.02) along with a significant decrease in resting and exercise RV ejection fractions (p less than 0.05) was found. We were unable to demonstrate any significant relationship between preoperative RV dysfunction and surgical outcome. We conclude that RV dysfunction is common in patients with LV aneurysm. Current techniques of operative intervention for this type of aneurysm seem to be followed by RV dilatation and impairment in RV function.

Adult↗
PubMed1988

Serum thyroglobulin as a preclinical tumour marker in subgroups of thyroid cancer.

Serum samples from a biological serum bank taken several years before the diagnosis of cancer, were analysed for S-Tg and S-TSH in 43 patients with thyroid cancer and compared to 128 healthy controls matched for age, sex, geographical region and time of blood sampling. The main finding was the difference in S-Tg between cases and controls, the highest values being found in sera from cases. Relative risk of thyroid cancer increases with increasing S-Tg levels (the global test giving P less than 0.0005). Extremely high levels were found in 4 cases with follicular and 3 with anaplastic cancers. No such statistically significant difference was found in S-TSH concentration. Possible explanations for the elevated S-Tg observed several years before clinically evident malignant tumour are discussed.

Adult↗
PubMed1988

Improvement in cardiac performance and exercise tolerance after left ventricular aneurysm surgery--a prospective study.

Forty two patients were studied prospectively by rest and exercise radionuclide ventriculography before and after (10 +/- 4 months) left ventricular aneurysm resection. Functional classification (NYHA) improved from 3.0 +/- 0.6 to 2.3 +/- 0.5 (p less than 0.0001) with an increase in double product (p less than 0.01) and total exercise workload (p less than 0.04) over preoperative values. End-diastolic volume was significantly reduced (p less than 0.0001) and resting global left ventricular ejection fraction (LVEF) improved significantly (p less than 0.03) after surgery, as did regional ejection fractions of the lateral/inferior wall (p less than 0.01). Cardiac index (CI) at rest, however, remained unchanged. Under exercise, improvement of global (p less than 0.0003) and regional ejection fractions (p less than 0.02) was more pronounced and a significant increase was also observed for CI (p less than 0.003). Improvement in left ventricular performance occurred both in patients with single and multiple vessel disease, but was more distinct in the latter group who additionally received coronary artery bypass grafts. These patients were furthermore postoperatively able to increase global LVEF at exercise (p less than 0.05). We conclude that aneurysm resection with or without coronary bypass relieves cardiac symptoms and improves exercise tolerance and left ventricular function at rest and on exercise in most patients.

Adult↗
PubMed1988

Evaluation of a radioreceptor assay for TSH receptor autoantibodies.

A commercial radioreceptor assay for TSH receptor autoantibodies (TRAb), based on solubilized porcine receptor and purified radio-iodinated bovine TSH, was tested in 264 subjects with a variety of thyroid disorders. The sensitivity of the assay for the detection of hyperthyroid Graves' disease was 91%. The assay specificity for Graves' disease was 95%. With the exception of one patient with Hashimoto's disease and one patient with de Quervain's subacute thyroiditis no subjects other than Graves' patients had detectable TRAb. Thus purely blocking TSH receptor autoantibodies were not detected with the assay. One female with thyroxine-treated idiopathic primary hypothyroidism who had given birth to two children with transiently elevated TSH, was found to have a circulating TSH-binding substance that resulted in an abnormally negative TRAb value, and highly discrepant results when TSH was measured with a double antibody TSH radioimmunoassay and an immunoradiometric assay. The TSH-binding substance was precipitated like a protein, but was not IgG. Similar findings have not previously been reported.

Adolescent↗
PubMed1986

Herpes zoster ophthalmicus with cerebral angiitis and reduced cerebral blood flow.

Two patients with herpes zoster ophthalmicus (HZO) who experienced a delayed contralateral hemiparesis, the so-called crossed zoster syndrome, are described. Particular emphasis is paid to the cerebral blood flow (CBF) findings studied with the Xenon-133 inhalation technique using single photon emission computed tomography (SPECT). In a 40-year-old female with right-sided hemiparesis, angiography showed multiple segmental narrowings of the intracerebral arteries. Cerebral computer tomography (CT) scans were normal. The CBF studied 11 months after the HZO showed a generalized reduction of flow which, however, was more pronounced in the left hemisphere. On re-examination 8 months later both the mean hemispheric flow and regional CBF (rCBF) had increased to normal values. In a 66-year-old male with dysphasia and right-sided hemiparesis, cerebral CT scans demonstrated two small deep left-sided infarcts. CBF examination showed a generalized reduction of flow in the left hemisphere. The flow was slightly increased on re-examination 12 months later. These findings suggest that the Xenon-133 inhalation method represents a useful way to demonstrate the CBF pattern in this group of patients.

Adult↗
PubMed1986

Hereditary thrombocytopenia with excessively prolonged bleeding time, corrected by infusions of platelet poor plasma.

In a family with hereditary thrombocytopenia, transfused normal platelets as well as their own platelets had a shortened survival in the patients' circulation (11). On the other hand, the patients' platelets survived normally when transfused to a normal recipient. Platelet-associated immunoglobulins or circulating platelet antibodies were not detected (immunofluorescence method). About 200 ml platelet poor plasma (PPP) from each of 4 normal donors was infused daily for 5 consecutive d to 1 afflicted family member, causing a rise of platelet count from 65 X 10(9)/l to 163 X 10(9)/l and a decrease of bleeding time from 28 to 11 min 7 d after the PPP was discontinued. The platelet count then gradually decreased and was 65 X 10(9)/l with a bleeding time of 30 min 16 d after the PPP was discontinued. In a repeated PPP infusion experiment a similar response was evoked. It is concluded that the afflicted family members must have a deficiency of some plasma principle necessary to keep platelets fit and circulating.

Antibodies↗
PubMed1986

Measurement of aortic regurgitation by Doppler echocardiography.

In an attempt to develop a new approach to the non-invasive measurement of aortic regurgitation, transmitral volumetric flow (MF) and left ventricular total stroke volume (SV) were measured by Doppler and cross sectional echocardiography in 23 patients without aortic valve disease (group A) and in 26 patients with aortic regurgitation (group B). The transmitral volumetric flow was obtained by multiplying the corrected mitral orifice area by the diastolic velocity integral, and the left ventricular total stroke volume was derived by subtracting the left ventricular end systolic volume from the end diastolic volume. The aortic regurgitant fraction (RF) was calculated as: RF = 1 - MF/SV. In group A there was a close agreement between the transmitral volumetric flow and the left ventricular total stroke volume, and the difference between the two measurements did not differ significantly from zero. In group B the left ventricular total stroke volume was significantly larger than the transmitral volumetric flow, and there was good agreement between the regurgitant fractions determined by Doppler echocardiography and radionuclide ventriculography. Discrepancies between the two techniques were found in patients with combined aortic and mitral regurgitation or a low angiographic left ventricular ejection fraction (less than 35%). The effective cardiac output measured by Doppler echocardiography accorded well with that measured by the Fick method. Doppler echocardiography provides a new and promising approach to the non-invasive measurement of aortic regurgitation.

Adolescent↗