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Biomedical subjects

A Hartmann

Publications and source records attributed to A Hartmann.

At least 415 records · Page 23Linked to original sources
PubMed1990

Cerebral blood flow and rheologic alterations by hyperosmolar therapy in patients with brain oedema.

Cerebral blood flow was assessed as initial slope index by 133-Xenon inhalation in 36 patients with brain tumours subjected to osmotic dehydration. The following solutions were employed: I. 20% mannitol, II. 40% sorbitol, III. 10% glycerol. Parameters affecting blood rheologic properties as Hct, plasma viscosity, red blood cell aggregation and fluidity were simultaneously studied. CBF which was reduced in the oedematous hemisphere with brain tumour increased during infusion and thereafter by mannitol or sorbitol, respectively. The blood flow response to glycerol was more delayed, less intense, but maintained longer. Hct and plasma viscosity were significantly reduced by all osmotic agents, while red blood cell fluidity fell and aggregation rose under mannitol. It is concluded that sorbitol (40%) is superior for emergency treatment with high ICP, whereas glycerol seems to be preferable to improve cerebral blood flow in oedematous brain.

Cerebrovascular Circulation↗
PubMed1990

Is technetium-99 m-pyrophosphate scintigraphy valuable in the diagnosis of cardiac amyloidosis?

Amyloidosis is a systemic disease frequently involving the myocardium and leading to functional disturbances of the heart. Amyloidosis can mimic other cardiac diseases. A conclusive clinical diagnosis of cardiac involvement can only be made by a combination of different diagnostic methods. In 7 patients with myocardial amyloidosis we used a combined first-pass and static scintigraphy with technetium-99 m-pyrophosphate. There was only insignificant myocardial uptake of the tracer. The first-pass studies however revealed reduced systolic function in 4/7 patients and impaired diastolic function in 6/7 patients. Therefore, although cardiac amyloid could not be demonstrated in the static scintigraphy due to amyloid fibril amount and composition, myocardial functional abnormalities were seen in the first-pass study.

Amyloidosis↗
PubMed1990

Effect of flunarizine on cerebral blood flow in baboons with or without focal cerebral ischaemia.

In baboons with or without regional cerebral ischaemia (achieved by transorbital clip of the middle cerebral artery), cerebral blood flow (CBF) was measured using the intra-arterial Xenon-133 technique during steady-state, slight hypotension, and hypocapnia before and after administration of various doses of the calcium antagonist flunarizine (0.5 mg kg-1, 1.0 mg kg-1, or 10 micrograms kg-1 min-1 over 30 min). In normal baboons flunarizine did not alter CBF significantly, but at reduced blood pressure it increased CBF by 19.9% owing to exaggerated vasodilatory autoregulation. During hypocapnia flunarizine impaired the physiological reduction in CBF owing to reduced vasoconstriction. In baboons with cerebral ischaemia, CBF measurements were stable and comparable with those in a control group using an arterial clip unless flunarizine was added. In a group of five flunarizine-treated animals, mean CBF after positioning of the clip was higher than in the control group. However, the increase in mean CBF varied significantly between animals, indicating that a secondary reduction in CBF due to postischaemic pathophysiological processes was not prevented consistently.

Animals↗
PubMed1990

Loop diuretics reduce lithium reabsorption without affecting bicarbonate and phosphate reabsorption.

The effects of the loop diuretics ethacrynic acid and bumetanide on lithium, bicarbonate and phosphate reabsorption were compared in 16 anaesthetized, normovolaemic dogs. In six dogs, ethacrynic acid (3 mg kg-1 body wt) significantly reduced absolute lithium reabsorption from 29.3 +/- 4.1 to 19.0 +/- 3.4 mumol min-1, fractional lithium reabsorption from 0.65 +/- 0.04 to 0.37 +/- 0.04 and fractional chloride reabsorption from 1.00 +/- 0.00 to 0.65 +/- 0.02. Bicarbonate and phosphate reabsorption did not decrease significantly. In six other dogs, bumetanide (30 micrograms kg-1 body wt) gave similar results. Absolute lithium reabsorption significantly decreased from 34.0 +/- 2.2 to 18.1 +/- 2.6 mumol min-1 and fractional lithium reabsorption decreased from 0.50 +/- 0.03 to 0.25 +/- 0.03. Fractional chloride reabsorption decreased from 0.98 +/- 0.00 to 0.61 +/- 0.05, whereas bicarbonate and phosphate reabsorption were not significantly altered. Thus, both loop diuretics greatly reduced lithium reabsorption. We propose that loop diuretics inhibit passive lithium reabsorption in the thick ascending limb of Henle's loop by reducing the lumen-positive electrical potential that drives passive cation transport.

Absorption↗
PubMed1990

[The content of fresh material, DNA and RNA in different tissues of turkeys during growth. 1. Analysis of the M. pectoralis superficialis, the M. quadriceps femoris, the cerebrum and cerebellum and the spinal cord].

First Communication: Analyses of M. pectoralis superficialis, M. quadriceps femoris, Cerebrum, Cerebellum, and Spinal Cord. The fresh matter level in the M. pectoralis superficialis of turkey was found to increase by a factor of 915, between the first and 224th days from hatching. DNA went up by a factor of 169. The protein: DNA quotient was increased 8.5 times. RNA concentrations in the same muscle went up from 2.65 +/- 0.06 to 6.02 +/- 0.30 mg/g of fresh matter, within the first and seventh days from hatching, and then dropped to 3.61 +/- 0.21 mg/g of fresh matter up to the 14th day, to 2.98 +/- 0.11 mg/g by the 28th day, and to 1.16 +/- 0.05 mg/g by the 224th day. The M. quadriceps femoris exhibited a 111-fold fresh matter increase, from the first through 224th days, while DNA went up by a factor of 44. The cerebrum exhibited a 3.9-fold increase of fresh matter and a 5.2-fold increase of DNA, between the first and 224th day. The cerebellum rises were 6.4-fold or 3.2-fold. Spinal cord values for the same period of time were 27.8-fold for fresh matter and 13.2-fold for DNA.

Animals↗
PubMed1990

[The content of fresh material, DNA and RNA in different tissues of turkeys during growth. 2. Analysis of the myocardium, the liver, the lungs, the kidney, the pancreas, the spleen and the duodenum].

The highest DNA concentration so far recorded from organs of turkey chicken one day after hatching was the lung value of 8.61 +/- 0.20 mg/g of fresh matter, while the lowest level amounted to 1.92 +/- 0.11 mg/g and was linked to the myocardium. DNA concentrations in the spleen went up from 5.93 +/- 0.26 mg/g on the first day to 13.04 +/- 0.93 mg/g on the 224th day. The highest total amount of DNA on the 224th day was 314.6 +/- 30.23 mg/g in the liver. A high RNA concentration on the first day from hatching was 8.74 +/- 0.14 mg/g in the liver and the lowest 2.51 +/- 0.12 mg/g in the myocardium. DNA levels for the whole period under review (first through 224th days) rose by the following factors: 246.3 in the spleen, 87.4 in the pancreas, 76.6 in the liver, 60 in the duodenum, 40.5 in the kidneys, 18 in the lung, and 31.3 in the myocardium. Functional implications relating to DNA, RNA, and protein variations are discussed in some detail.

Animals↗
PubMed1990

[The effect of electromagnetically produced shock waves on calcified, stenosed aortic valves].

To determine if electromagnetically generated shock-wave lithotripsy has potential application for treatment of stenotic, calcified aortic valves, 38 cusps of surgically excised human aortic valves were studied. Valves were weighed, photographed, and calcium deposition was determined by x-ray. Stiffness was determined by palpation and by measuring the pressure gradient generated in a perfusion system. Valves were exposed to shock waves at 16 or 18 kV with 200 or 400 impulses each. Twenty valves reacted to exposure to shock waves with a reduction in pressure gradient of 1.9 +/- 2 cm H2O. Calcified valve area was reduced by 3.5 +/- 1.3 mm2. Valves without changes in pressure gradient showed a reduction of 7.1 +/- 2 mm2 of calcified valve area. There was no significant difference in weight loss. Using a small focus (4 mm) there was a significant reduction in pressure gradient and calcified valve area, but not in weight; with a large focus (8 mm) reduction in calcified valve area, gradient, and weight was significant (p less than 0.05). Changes in valve stiffness were independent of weight loss and reduction in calcified valve area. In conclusion, shock-wave lithotripsy is capable of reducing stiffness of calcified aortic valves, presumably by fragmentation of tissue calcium deposits.

Aortic Valve↗
PubMed1990

[Comparison of the oxygen deficit and ischemia pain threshold in patients with silent and symptomatic myocardial exercise-induced ischemia].

In 39 patients with angiographically documented coronary artery disease and silent or symptomatic myocardial ischemia under exertion it was investigated if there is a difference in forearm skeletal muscle ischemia and ischemic pain threshold. The degree of myocardial ischemia was determined by plethysmographically measured reactive hyperemia. In 12 asymptomatic and eight symptomatic patients maximal reactive hyperemia was induced by ischemic work in the forearm skeletal muscle. After termination of ischemia there was a significantly higher reactive hyperemia at 20, 90, and 180 s in the asymptomatic patients. Furthermore, nine asymptomatic and 10 symptomatic patients underwent symptom-limited ischemic work until weakness or pain developed. Under these conditions reactive hyperemia as a parameter of oxygen deficiency was higher in the asymptomatic patients. The difference was not statistically significant. There was, however, a significantly higher incidence of ischemic pain in the symptomatic patients. It can be concluded that patients with asymptomatic myocardial ischemia tolerate a higher oxygen deficit in the working forearm and have a higher pain threshold than patients with symptomatic ischemia.

Angina Pectoris↗
PubMed1990

Differentiation and retrodifferentiation of U937 cells: reversible induction and suppression of intermediate filament protein synthesis.

Significant morphological and functional changes were observed when human monoblastoid U937 tumor cells growing in suspension were induced by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) for 72 h to differentiate along the monocyte/macrophage pathway. These include adherence of the cells to each other and to the substratum, alterations in cell-surface antigen expression and cessation of autonomous proliferation. In this study, we show by both, hybridization analysis of RNA and immunoblotting that an enhanced expression of the intermediate filament (IF) subunit proteins vimentin, lamin A and lamin C accompanied the TPA-induced differentiation process. After long-term culture of differentiated U937 cells in the absence of TPA (more than 28 days), however, the adherent cells retracted their pseudopodia, detached and started again to proliferate. This "retrodifferentiation" process, not previously described was paralleled by a rapid down-regulation of both, IF mRNA and protein synthesis back to the level of undifferentiated U937 control cells. These data suggest a functional relationship between the expression of vimentin and lamins A and C and the differentiation process taking place in these cells.

Cell Differentiation↗
PubMed1990

[Psychiatric, psychosomatic and medical psychological consultation and liaison activity in West Germany. Results of a survey].

Results of the first survey of consultation/liaison psychiatry and psychosomatics in the Federal Republic of Germany are presented and discussed. All departments and units of psychiatry, psychosomatics and medical psychology were asked to fill in a questionnaire, characterizing the institution in question, the type and degree of cooperation with somatic units and the experiences made therewith, as well as special issues like the use of data bases and diagnosis, questions of organization, professional training and research in C/L work. The 177 institutions which replied (67% of the total of 263 institutions addressed) can be regarded as representative for those institutions which are involved in consultation/liaison work. As compared with psychiatry, psychosomatic (and medical psychology) departments are especially involved in C/L-work. Due to insufficient financing and relative neglect as concerns research and professional training and exchange, C/L-work in the Federal Republic of Germany at present is far from providing general hospital inpatients with the mental health care required, as indicated by prevalence estimates. Reasons for this are discussed and suggestions as to minimal standards of C/L-care are provided.

Germany, West↗
PubMed1989

An intravascular technique to occlude the middle cerebral artery in baboons.

A technique is described for occlusion of the middle cerebral artery in the baboon by an intravascular approach. A torque catheter is introduced under fluroscopic control into the internal carotid artery by transfemoral catheterization. In conjunction with a guide wire an infusion microcatheter with increasing stiffness from the distal tip to the proximal shaft is positioned in the proximal part of the middle cerebral artery via the introducer system. N-Butyl-2-cyanoacrylate-monomers are injected into the microcatheter for permanent occlusion of the middle cerebral artery. The procedure was successfully completed in 21 out of 24 baboons. In 3 baboons the occlusion could not be achieved since the torque catheter could not pass proximal extreme tortuosities of possibly arterisclerotic internal carotid arteries. Infarcts in the 21 animals were confirmed by computerized tomography and/or autopsies in all animals.

Animals↗
PubMed1989

Role of substance P in immediate-type skin reactions induced by staphylococcal enterotoxin B in unsensitized monkeys.

The staphylococcal enterotoxin B (SEB)-induced immediate-type skin reaction in unsensitized monkeys was used as a nonimmunologic mast cell stimulation to search for possible involvement of local neural mechanisms. Evidence is presented that substance P (SP) plays a predominant role in mediating intradermal SEB challenge in unsensitized monkeys. With a rabbit SP antiserum directed against the C-terminal region of SP, a concentration-dependent inhibition of SEB-induced skin reactivity could be demonstrated. Furthermore, a rabbit antiserum directed against the mast cell activating N-terminal part of SP was capable of impeding SEB-induced skin reactions totally. By use of SP antagonists, significant reduction of skin reactions evoked by SEB was found. Finally, capsaicin pretreatment of the skin caused a substantial inhibition of SEB-induced skin reactivity. These data suggest that SEB exerts its effect on cutaneous mast cells via stimulation of primary sensory neurons that contain SP. Moreover, a new in vivo model is described for studies of nerve-mast cell interactions.

Animals↗
PubMed1989

Alteration of intracranial pressure, cerebral blood flow, autoregulation and carbondioxide-reactivity by hypotensive agents in baboons with intracranial hypertension.

Intracranial pressure (ICP) was recorded by epidural transducer and cisterna magna catheter, and regional cerebral blood flow (rCBF) using the intraarterial Xenon 133-technique were measured in baboons with normal and during increased ICP provoked by an inflatable balloon positioned subdurally. Arterial blood pressure was altered by controlled infusion of Sodium-nitroprusside (SNP), Nitroglycerine (NG) or Trimetaphan (TMP) with the aim of reducing blood pressure by about 20%. During exflated balloon SNP provoked an increase of ICP which was more prominent than with NG and TMP. During increased ICP (due to inflation of the balloon) again SNP led to a higher further increase of ICP than both NG and TMP. rCBF rose during the state of normal ICP when SNP was infused. This was not observed with infusion of NG or TMP. When ICP was increased again by inflation of the balloon all 3 substances reduced rCBF, indicating damage to the autoregulation. CO2-reactivity as measured by induced hyperventilation with reduction of arterial CO2-tension was affected by all 3 substances thus indicating impairment of vasoconstriction during increase of ICP and simultaneous decrease of blood pressure. However, this impairment of physiological vasoconstriction was more prominent with SNP than with NG and TMP. The results indicate that all 3 substances should be used with care to reduce blood pressure during surgery or under intensive care condition, particularly in patients with increased ICP.

Animals↗