Search PubMed⌕ Search

Biomedical subjects

K Alexander

Publications and source records attributed to K Alexander.

At least 109 records · Page 6Linked to original sources
PubMed1991

[Reflection spectrophotometry determination of cutaneous hemoglobin saturation in patients arterial occlusive diseases].

By a spectrophotometrical method, the oxygenation and relative concentration of hemoglobin in the skin of the forefoot was determined in 40 patients with advanced peripheral arterial occlusive disease. While the Hb-saturation at rest was hardly different from normals, leg elevation provoked a marked decrease of both parameters, especially in patients with critical ischemia. In these patients, reactive hyperemia was markedly delayed and impaired. External heat application failed to cause a hyperemic saturation increase in 14 patients and produced a decrease in 8 patients, 6 of whom experienced an infavourable clinical outcome. The method seems specially suited to assess states of severe ischemia.

Aged↗
PubMed1991

Skin surface oxygen pressure in healthy volunteers and patients with arterial occlusive disease.

When measuring transcutaneous oxygen pressure at an electrode core temperature of 37 degrees C autoregulating mechanisms of skin microcirculation can be studied. Because of poor reproducibility of a single PO2 measurement we determined skin surface oxygen pressure fields out of 50 or more PO2 values. At the forefeet and calves of healthy volunteers the histograms were slightly left-shifted with median PO2 of 4 mm Hg. Patients with multilevel arterial occlusive disease and low systolic ankle pressure presented with a disturbed PO2 distribution with very low PO2 values close to zero. About 16% of measurements were above 10 mm Hg. In contrast, diabetics had significantly higher PO2 (median 8 mm Hg) at the forefoot level when compared with healthy volunteers or patients without diabetes.

Adult↗
PubMed1991

[Long-term results 10-14 years following implantation of Y-prostheses for arterial occlusive disease].

Between 1973 and 1977 169 patients underwent implantation of bifurcated prostheses for arterial occlusive disease. Perioperative and follow-up data 10-14 years after operation were retrospectively assessed. The angiologic status of living patients was compiled. Impact of following risk factors was investigated with multivariant analysis. Coronary artery disease, hypertension, smoking, diabetes mellitus, Pulmonary disease, renal insufficiency, obesity. Follow-up was 98.8%. Preoperatively over 90% of the patients investigated had been in grade IIb (Fontaine) or worse (33% grade IV). Early mortality was 5.3% (1973 = 15%, 1977 = 5.3%, 1987/1988 = 1.8%) and was mainly related to cardiopulmonary factors. Reoperation was necessary in 69 patients (149 procedures, no mortality, 38 amputations). Late mortality was 75% (120 of 160 patients) and mainly due to cardiac problems. The 10-year-actuarial-survival (37%) was reduced due to following combinations of risk factors: Myocardial infarction/smoking/obesity (n = 41) 17%, diabetes/smoking (n = 36) 17% hypertension/myocardial infarction (n = 24) 8%. Clinical condition of the living patients (n = 40) was: 48% grade I, 28% grade IIa, 18% grade IIb, none grade III, 8% grade IV. Long term results following implantation of bifurcated prostheses for arterial occlusive disease show, that quality of life is consistently improved. Reoperation is necessary in almost half of the patients due to the progressive disease. Late mortality is closely related to the underlying arteriosclerosis. Life expectancy of our patients does not significantly differ from the normal population and is probably a sequelae of the close follow-up.

Adult↗
PubMed1991

Alterations of the nailfold capillary morphology associated with Raynaud phenomenon in patients with systemic lupus erythematosus.

Quantitative analysis of nailfold capillary morphology was performed in age and sex matched groups of 29 patients with systemic lupus erythematosus (SLE) presenting Raynaud phenomenon (RP), 29 RP negative patients with SLE with the same duration of the disease, and 29 healthy controls. Percentages of tortuous, meandering and bushy capillaries were significantly increased in both groups of patients without influence of RP. Capillary density was lower, mean diameters of the capillary loops were higher in patients, especially when RP was present (at the venular branch in microns, mean +/- SD: controls: 15.0 +/- 2.0, RP negative patients with SLE: 17.6 +/- 3.6, RP positive patients with SLE: 20.5 +/- 6.3). In a subgroup of 13 patients with frequent Raynaud's attacks (more than 1/week), diameters were still higher (22.1 +/- 7.1, p to controls less than 0.0005; p to RP negative patients less than 0.05). In patients with SLE, the prevalence of RP seems not to be associated with the increased number of abnormal capillaries but with capillary enlargement, correlating with the frequency of attacks.

Adult↗
PubMed1990

Microbody phosphoglycerate kinase of Trypanosoma brucei: expression and complementation in Escherichia coli.

In the primitive eukaryotic parasite, Trypanosoma brucei, most of the enzymes of glycolysis are located within microbody organelles called glycosomes. Proteins destined for the glycosome are synthesized on free ribosomes and post-translationally translocated into the organelle. The gene, gPGK, encoding the glycosomal isozyme of phosphoglycerate kinase (gPGK), was cloned adjacent to a T7 promoter and cotransformed with a plasmid encoding T7 RNA polymerase into Escherichia coli Pgk-cells. Functional complementation occurred, but only after the creation of a ribosome-binding site by mutagenesis. This represents the first example of complementation of an E. coli mutant with a gene encoding a microbody protein. Enzymatically active recombinant gPGK was purified to near homogeneity by ion exchange chromatography from highly expressing E. coli. The recombinant protein will aid in studies of glycosomal biogenesis.

Animals↗
PubMed1990

[Duplex sonography: accuracy, reproducibility and possibilities for error. Checking quantitative flow measurements against an in vitro model].

Using a pulsatile model of tubes, duplex-sonographic measurements of flow were compared with actual flow. The correlation coefficient between actual and duplex-sonographically obtained flow was 0.975, mean percentage deviation being -18.1% (P less than 0.0001). The obvious scatter (margin of error -69.2 to +50%) is to be explained by the simulation closely imitating a real situation: the transducer was hand-held and tubes were placed in muscle or fat tissue. Accuracy was increased by multiple measurements, especially when taking into account only the maximal value of any series of measurements. Vessel diameter was easy to measure accurately (mean error less than 0.01% [-18.7 to +9.4%]). Repeated measurements of flow velocity had only a small scatter (coefficient of variance 0.064). In muscle or fat the Doppler signal was attenuated and the error the greater the deeper the level at which measurements were made. Low flow (common in patients with obstructive vascular disease) can also cause faulty results.

Analysis of Variance↗
PubMed1990

Skin surface oxygen pressure fields during administration of prostaglandin E1 in patients with arterial occlusive disease.

Prostaglandin E1 is offered as a new therapeutic agent in the treatment of severe peripheral arterial occlusive disease. Especially when treating patients with ulcers or gangrene, the oxygen tension of the skin should improve during PGE1 administration. The new technique of assessing skin surface oxygen pressure histograms allows study of the skin microcirculation in vivo. Oxygen histograms were determined on the forefeet of 19 patients with different degrees of disease and different occlusion levels before and during a single intraarterial infusion of PGE1 at a dosage of 1.5 ng/kg body weight/min. Only 9 patients showed improvement during the infusion period. Skin oxygen pressure was increased to a large extent only in patients assumed to suffer from diabetic microangiopathy. The effect of a long-term therapy with PGE1 on skin microcirculation remains to be settled.

Adult↗
PubMed1990

Skin microcirculation and regional peripheral resistance in patients with chronic renal anaemia treated with recombinant human erythropoietin.

Skin microcirculation and regional peripheral resistance were studied in 14 patients with renal anaemia during therapy with recombinant human erythropoietin. Haematocrit was raised from 20.0 to 31.3% after 10-12 weeks of treatment and remained stable over another period of 12 weeks. Antihypertensive treatment had to be intensified in five patients. Regional calf blood flow decreased significantly; accordingly, calculated peripheral vascular resistance was increased by more than 100%. However, transcutaneous oxygen pressure (37 degrees C and 44 degrees C) increased significantly. The pathological vasoconstrictor response of skin capillaries was not influenced. There were no significant differences of any parameter between the patients requiring reinforced antihypertensive therapy and those with stable blood pressure. In conclusion skin oxygenation may be improved by erythropoietin treatment to a large extent despite an increase in calculated total limb vascular resistance.

Adult↗
PubMed1990

[Duplex ultrasound measurement of morphologic parameters before and following repeated puncture of the femoral artery for intermittent infusion therapy].

In order to estimate morphologic changes of the femoral artery after an intermittent intraarterial infusion therapy duplex scanning was performed before therapy, immediately after a series of 26 (10 to 52) infusions, and 30 weeks after hospital discharge. Minimum and maximum values of internal and external vessel diameter and thickness of wall were estimated in the common femoral artery, superficial femoral artery, and deep femoral artery. The external diameter values and the thickness of wall increased significantly after therapy. After 30 weeks these values decreased but did not reach the initial values.

Alprostadil↗
PubMed1990

[Biochemical effects of discontinuous muscle work in arterial occlusive disease].

8 patients with arterial occlusive disease were examined for the quantity of their lactate acidose during two treadmill tests. Test I was interrupted after 6 minutes. 20 minutes later test II followed. Lactate, pyruvate and blood gases were determined. There are significant differences between these two exercise tests in term of lactate differences between rest and exercise. It is assumed that the rate of glycolysis is reduced during exercise in test II.

Arterial Occlusive Diseases↗
PubMed1989

The inactivation of rhodanese by nitrite and inhibition by other anions in vitro.

Cyanide detoxification in mammals occurs, in part, by sulfur transfer by rhodanese to form the less toxic thiocyanate. Thiosulfate and nitrite are often used in combination for the treatment of cyanide intoxication. This report shows that nitrite can inhibit the rate of sulfur transfer by rhodanese in vitro. Nitrate, chloride, sulfate, and acetate were also examined as inhibitors. Inhibition by nitrite appeared to be more complex than for the other anions tested. Closer examination showed that nitrite can inactivate the sulfur-free rhodanese. Our observation leads to the suggestion that, in vivo, either rhodanese is maintained in its more stable sulfur-substituted form or cellular compartmentalization prevents inactivation by nitrite.

Animals↗