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Biomedical subjects

K Alexander

Publications and source records attributed to K Alexander.

At least 163 records · Page 9Linked to original sources
PubMed1985

Doppler frequency spectrum analysis and digital subtraction angiography in carotid artery disease.

The aim of the study was to evaluate the diagnostic accuracy of frequency spectrum analysis complementary to direct Doppler sonography in comparison to conventional biplane arteriography and transvenous digital subtraction angiography in internal carotid artery stenosis. In a group consisting of 229 carotid arteries visualized by conventional biplane arteriography, Doppler frequency spectrum analysis had a specificity of 97% and concerning all stenoses and occlusions, a sensitivity of 89%. In a second group consisting of 198 carotid arteries imaged by transvenous digital subtraction angiography, Doppler sonographic examination had a specificity of 65% only, and concerning all categories of stenoses and occlusions a sensitivity of 85%. These differences concerning specificity are not interpreted as false positive diagnoses in Doppler spectrum analysis but are considered to be due to false negative findings of digital subtraction angiography in stenoses of less than 50% vessel diameter reduction.

Carotid Artery Diseases↗
PubMed1985

Drug-induced alterations in muscle tissue oxygen pressure in patients with arterial occlusive disease.

Muscle tissue oxygen pressure fields were examined on the surface of the gastrocnemius muscle of 17 patients with peripheral arterial occlusive disease before and during intra-arterial administration of dextran 40 50 ml/50 min, xantinolnicotinate 600 mg ad 50 ml NaCl 0.9%/50 min and prostaglandin E1 1.0-2.5 ng/kg/min ad 50 ml NaCl 0.9%/50 min. Median PO2 increased in 6 out of 7 patients up to 214% when dextran 40 was given and up to 300% in all 5 cases who received prostaglandin E1. In some patients the histograms' distribution type changed during the treatment from a scattered form which indicates microcirculatory disorders to a bell-shaped form which is expected when microcirculation is undisturbed. Intra-arterial administration of xantinolnicotinate was without any influence on poststenotic muscle PO2. The registration of muscle tissue oxygen pressure fields is an ideal method for determining the effect of so called vasoactive drugs in treatment of peripheral arterial occlusive disease.

Adult↗
PubMed1985

Studies of tibial subchondral bone density and its significance.

We examined the relationships between the density of the subchondral bone of the proximal end of the tibia and the location and condition of the overlying articular cartilage and menisci. We took coronal sections of the tibial plateaus and of the overlying articular cartilage and menisci from human knee joints that were grossly free of osteoarthritis. The specimens were examined for the presence of cartilage fibrillation using the India-ink technique of Meachim. Bone density was determined using the Quantimet picture-point analyzer. Fibrillation of articular cartilage was observed only in the articular cartilage that was not covered by meniscus and lying mesial to it, which supports the concept that the meniscus confers a protective effect on the articular cartilage. The density of the bone underlying the meniscus was lower, and was inversely related to the thickness of the meniscus and directly related to the thickness of the articular cartilage. In four knees from which the menisci were absent, the bone density was increased at the periphery. We suggest that there is a trinitarian relationship between the meniscus, cartilage, and subchondral bone, in which structural changes in any one of the three causes secondary pathological adaptive changes in the other two.

Adult↗
PubMed1985

Topical nitroglycerin ointment in Raynaud's phenomenon.

The purpose of the study was to evaluate the hemodynamics of nitroglycerin ointment in Raynaud's phenomenon. 22 patients (15 women and 7 men aged 25-75 years) suffering from Raynaud's phenomenon were investigated in a double-blind paradigm. Blood flow measurements were performed by venous occlusion plethysmography. Cardiac output was registered by means of impedance cardiography. 800 mg nitroglycerin ointment 2% was applied on one hand only. In the placebo group, finger blood flow, blood pressure, heart rate, and cardiac output did not change significantly. In the group receiving nitroglycerin, finger blood flow increased significantly from 21.6 +/- 6.0 to 31.7 +/- 7.0 ml/100 ml/min. Systolic blood pressure decreased from 126 +/- 4 to 118 +/- 3 mmHg. Cardiac output significantly decreased from 7.3 +/- 0.8 to 6.3 +/- 0.5 l/min. It is concluded that nitroglycerin ointment in Raynaud's phenomenon has a local and a systemic effect as well, because, on the one hand, cardiac output and blood pressure decreased whereas, on the other hand, the increase in finger blood flow was more marked in the treated hand than in the contralateral control fingers.

Administration, Topical↗
PubMed1985

[Heart and skeletal muscle scintigraphy with thallium 201].

The regional uptake of Thallium-201 is correlated with the regional distribution of cardiac output in the myocardium as well as in skeletal muscle. Thallium-201 perfusion scans will detect peripheral occlusive arterial disease (POAD) as well as coronary heart disease (CHD). In a prospective study we examined POAD patients and CHD patients by both myocardial and leg stress scintigraphy. In normals the uptake ratio of both calves was 1.03 +/- 0.05 (mean +/- SD), while in all patients with proven POAD the ratio was higher than 1.2. In 12 of 16 patients with myocardial infarction the high ratio indicated a coincidence of POAD and CAD, confirmed by other techniques in all but one patient. In patients with suspected CHD there was an increased ratio in 8 of 21;6 of these patients also had an abnormal myocardial stress scan, while there were only 4 abnormal scans in the 13 patients with normal leg uptake. In 19 of 26 patients with known POAD the myocardial stress scan was abnormal, indicating CHD in 75% of this group. This was confirmed in most patients by coronary angiography. The combination of myocardial and leg stress scan can be carried out without further radiation exposure to the patient and in a few minutes. It is a new approach to determine the possible coincidence between POAD and CHD; it should be performed in all patients referred for TI-201 myocardial stress scintigraphy.

Arterial Occlusive Diseases↗
PubMed1985

[Ergotamine-induced disorders of the peripheral blood circulation--a case report].

Ergotism with severe arterial circulatory disorders, sometimes leading to amputation of the leg, is a severe complication following application of drugs containing ergotamine. Often the diagnosis is made by the typical angiographic findings. The history, clinical course and a new treatment in a very severe case is reported.

Adult↗
PubMed1985

Effects of different living settings on the performance of mentally retarded individuals.

Motivation for adult attention and support, wariness, and expectancy of success over a 2-year period were assessed for 58 mentally retarded individuals residing in either large central institutions, regional centers, or group homes. Males were found to be more responsive to social reinforcement than were females in all living settings. Wariness was found to increase over time in the large central institutions, whereas it decreased in the smaller settings. Individuals with greater preinstitutional social deprivation had a lower expectancy of success. In addition, over the 2-year period, the expectancy of success of individuals from high-deprived backgrounds remained low, whereas it increased for individuals from less socially deprived preinstitutional backgrounds.

Adolescent↗
PubMed1985

[Oxygen pressure fields in ulcers of the lower leg].

Using a multi-wire surface electrode, oxygen pressure fields were determined in leg ulcers of 11 patients with chronic venous insufficiency (cvi). In three of them, cvi was combined with arterial occlusive disease. The histograms of all patients with very low PO2 values revealed microcirculatory disturbances of the ulcer tissue. The influence of leg position is reflected in the histograms. Patients with cvi showed higher PO2 values when the leg was raised in comparison with when it was in the hanging position. The patients with mixed ulcerations showed a significant increase in tissue PO2 when the leg was in the hanging position, which shows the importance of arterial perfusion pressure. After a compression bandage had been applied to the legs with cvi, the tissue oxygen pressure of the ulcers increased markedly, probably as a result of diminished blood stasis. These results can be explained either by a rarefaction of capillaries in the ulcer tissue or by fibrin diffusion barriers around the capillaries. The changes in the histograms after bandaging are thought to be caused by an improvement in venous circulation.

Adult↗
PubMed1984

[Doppler frequency spectrum analysis of extracranial carotid artery lesions].

Signals registered from the extracranial carotid artery by direct Doppler-ultrasound with a MHz transducer were subjected to real-time frequency spectrum analysis. A systolic maximal frequency over 3500 Hz was considered abnormal, together with a broadened spectrum. The study was made on 157 subsequently operated carotid arteries, not all of which had previous angiographic studies. Of 47 with a normal angiogram 45 were correctly classified non-invasively (specificity 96%). The non-invasive diagnosis was correct in 16 of 17 occlusions of the internal carotid artery demonstrated angiographically. An abnormal Doppler frequency analysis was present in only 7 of 14 stenoses with a decreased vessel lumen below 25%. An abnormal Doppler frequency analysis was present in 78 of 79 stenoses with more than 25% reduction in lumen diameter, diagnostic sensitivity for all stenoses being 91%.

Adult↗
PubMed1984

Endemic Lassa fever in Liberia. I. Clinical and epidemiological aspects at Curran Lutheran Hospital, Zorzor, Liberia.

In a study to assess the epidemiological and clinical aspects of endemic Lassa fever (LF) in Liberia at Curran Lutheran Hospital (CLH), 44 cases were diagnosed by virological and serological techniques over a 22-month period. During one calendar month, testing of febrile patients admitted to the medical-surgical ward revealed six cases of LF, 13% of all febrile cases and 17% of those who were tested. As the study progressed the diagnostic skills of the hospital staff improved. The most common mistake was the diagnosis of a case of LF as pneumonia; the most potentially serious diagnostic problem was differentiating LF from typhoid fever, a readily treatable infection. LF may also mimic other diseases such as aseptic meningitis, pelvic inflammatory disease, gastroenteritis or arbovirus infection. We found a previously unreported symptom of LF, rib tenderness typical of costochondritis. The mortality rate in the medical-surgical ward was 5.4%; the over-all case-fatality rate was 13.6%. Women outnumbered men by nearly three to one, and had a higher mortality particularly noted in the pregnant. LF is common at CLH, and as many as 100 cases may occur annually at this hospital.

Adolescent↗
PubMed1984

[Incidence of peptic ulcer in an inpatient angiologic patient sample].

Incidence of peptic ulcers in hospitalized patients with arterial occlusive disease without history or clinical symptoms of ulcer disease was 32% and four times higher than in patients with acute phlebothrombosis. Possible etiological factors could be: decreased blood perfusion of gastric or duodenal mucosa because of generalized arteriosclerosis, intake of ulcerogenic drugs, chronic abuse of nicotine, and stress due to the underlying arterial occlusive disease. Patients with inflammatory vascular disease are affected as often as are patients with arteriosclerotic disease. Routine endoscopic examination of the upper GI-tract should be performed in such patients in order to exclude potential bleeding sources before treatment with fibrinogen lowering drugs is started.

Adolescent↗
PubMed1983

[Percutaneous transluminal angioplasty of the lower extremities in the elderly].

Results of percutaneous transluminal angioplasty (PTA) for peripheral arterial occlusion were compared between a group of 41 patients aged over 60 years and one of 39 patients under 60 years. In the older patients the proportion of those in a decompensated state was 61%, more than double that in the younger ones. 54% of the older patients were diabetics with a poor peripheral vascular outflow bed; conservative treatment failed in them and surgical intervention was not possible. A primary success rate of PTA was 87% in the older patients, no worse than in the younger ones. Long-term follow up of both groups indicated that PTA in the compensated stage achieved prolongation of pain-free walking distance or absence of symptoms in 74%. Threatened leg amputation could be avoided in 80% of the younger and 60% of the older patients. Limited amputation was performed in 20% of the older patients with decompensated vascular disorders. The most frequent complication of PTA was embolization into the small vessels of the lower leg, in nearly 30% of patients. But only once did this worsen the clinical state, and this was transitory.

Adult↗