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Biomedical subjects

G Mayer

Publications and source records attributed to G Mayer.

At least 145 records · Page 8Linked to original sources
PubMed1996

Cardiovascular effects of increasing hemoglobin in chronic renal failure.

Partial correction of renal anemia by the use of recombinant human erythropoietin is associated with various effects on cardiovascular performance parameters. A decrease in cardiac output as well as an increase in systemic peripheral resistance have been noted and the pathogenetic basis of these changes will be discussed. Furthermore this article will focus on the potential cardiovascular consequences of prolonged correction of anemia in patients with renal failure. The literature on the clinical implications, such as left ventricular hypertrophy, peripheral arterial occlusive disease and finally patient care costs, will be discussed.

Anemia↗
PubMed1996

Reactive oxygen species and glomerular injury.

The generation of reactive oxygen species (ROS) has been recognized as a common pathway of tissue damage in a wide range of seemingly unrelated disorders like atherosclerosis or reperfusion injury [1, 2]. Not surprisingly therefore a growing body of evidence suggests that ROS are also important mediators in renal disease where they have been noted to be of importance in vascular, glomerular, tubular and interstitial damage [3-7]. In this review we will give a short description of the nature of ROS, their intrarenal production as well as their degradation by local defense mechanisms. We then will focus on the impact of ROS in glomerular injury trying also to summarize the experimental as well as human data (as far as they are available) as to how 'antioxidants' might be effective drugs for the treatment of specific disorders.

Animals↗
PubMed1996

Angiotensin-converting enzyme polymorphism in patients with terminal renal failure.

An insertion/deletion polymorphism has been described for the gene that encodes the angiotensin-converting enzyme. The deletion allele is associated with higher angiotensin-converting enzyme plasma levels, which ultimately might lead to increased angiotensin II concentrations. Because angiotensin II is a mediator for progressive renal injury, this study determined the frequency of distribution of the angiotensin-converting enzyme insertion/deletion polymorphism in 106 hemodialysis patients and in a group of 95 healthy control patients. There was no difference between the two groups as far as the distribution of the insertion and deletion allele was concerned. Of the total hemodialysis population, 26.4% exhibited the deletion/deletion genotype, as compared with 37.9% of the healthy control population. Also, when patients with terminal renal failure as a result of glomerular disease were analyzed separately, the frequency of the deletion/deletion genotype was identical to that of the control group. Furthermore, the frequency of hypertension, coronary artery disease, left ventricular hypertrophy, and dilated cardiomyopathy, were analyzed according to the angiotensin-converting enzyme genotype, but the deletion allele could not be defined as a risk factor in the study's hemodialysis population. It was therefore concluded that the angiotensin-converting enzyme insertion/deletion polymorphism is not a major risk factor for development of end-stage renal failure. Additionally, in hemodialysis patients, there is no association between the risk for cardiovascular diseases and the angiotensin-converting enzyme genotype.

Adult↗
PubMed1996

[The in vitro induction of monocyte chemotactic protein-1 and interleukin-8 in whole human blood by low molecular weight thymus peptides].

Thymic peptides show immunoreconstitutive und tumor suppressive effects. They are used in oncology to improve the immunological status of patients. Chemokines are able to activate immune cells and inhibit tumor growth. In this study it was proved whether low molecular thymic peptides are able to increase the secretion of the chemokines monocyte chemotactic protein-1 (MCP-1), interleukin-8 (IL-8), macrophage inflammatory protein-1 alpha (MIP-1 alpha) and macrophage inflammatory protein-1 beta (MIP-1 beta) as well as the cytokine tumor necrosis factor-alpha (TNF-alpha) which is not related to chemokines using cell cultures of human whole blood. The thymic peptides induced a significant (p < 0.05) elevated secretion of MCP-1 and IL-8 whereas for MIP-1 alpha, MIP-1 beta and TNF-alpha no significant chances were seen. MCP-1 and IL-8 showed divergent dose-dependent effects and a different time kinetic of their secretion. The MCP-1 concentration correlated positively with the count of monocytes in whole blood of the volunteers while the IL-8 concentration in dependence with the incubation time correlated positively with the count of granulocytes or monocytes of the volunteers. The results indicate an activation of monocytes and/or granulocytes by low molecular thymic peptides followed by selective elevated secretion of MCP-1 and IL-8.

Adult↗
PubMed1996

[Performance and personality of patients with hypersomnia].

5 groups of patients with hypersomnia (narcolepsy, posttraumatic, psychophysiologic, idiopathic hypersomnia and circadian sleep-wake disorders) were tested with a battery of psychometric tests (FPI, MMPI, BVND, BIV, Benton, d2, WIP), visual vigilance test, polysomnography and MSLT in order to investigate the context between personality and performance. MSLT showed a range from clear pathologic to borderline sleep latencies among all groups, only patients with posttraumatic hypersomnia and narcolepsy displayed sleep onset REM. Correct results of vigilance tests correlated negatively with performance-motivation and orientation in patients with narcolepsy and posttraumatic hypersomnia, whereas there was positive correlation for patients with idiopathic hypersomnia. In patients with psychophysiologic hypersomnia performance orientation and false reactions correlate negatively. Patients with posttraumatic hypersomnia have better results on d2. Benton and vigilance tests than all other groups. Results of personality diagnosis are similar to those of healthy subjects, while patients with psychophysiologic hypersomnia are more sensible than all other groups with high social fears and the highest disposition among all groups toward somatic complaints. Patients with idiopathic hypersomnia show strong introversion and inhibition. Patients with circadian sleep-wake disorders display the most striking personality disorders, which are most probably sequelae of their strong disease-dependent impairment. The degree of personality disorder seems to be strongly dependent on the duration of the hypersomnias. The assessment of the whole set of tests can only be recommended for patients with psychophysiologic hypersomnia and circadian sleep-wake disorders, a few tests suffice to describe the other groups.

Adult↗
PubMed1996

[Aspects of medical expert assessment of sleep-waking disorders].

Knowledge gained in sleep medicine over the past 10 years has not yet been incorporated into laws for the severely handicapped and pension law. The impact of increased accident incidence of patients with hypersomnia has not yet been recognized in the guidelines for medical diseases in automobile traffic in governmental driving regulations. In preparation for implementation of sleep-wake disorders into medico-legal jurisdiction they must be introduced to the guidelines as a separate medical entity according to the International Classification of Sleep Disorders. Due to different prognoses sleep-wake disorders should be separated into reversible and irreversible disorders. To decide on driving ability, degree of disablement and permanent and total disability therapeutic efficiency should be documented by methods acknowledged in sleep medicine. Professional and nonprofessional drivers and personnel in charge of responsible monitoring should be submitted to regular therapy controls. Degree of disablement or permanent and total disability can only be recommended for patients with symptoms partially or completely refractory to therapy. Accompanying diseases posing a high health risk or those causing sleepiness themselves have to be included in the overall judgement. Sleep specialists have to be nominated as expert witnesses and should furthermore contribute to multiplication of knowledge on sleep medicine for public health officers.

Accidents, Traffic↗
PubMed1996

[Effects of diuretic therapy on electrolyte and acid-base homeostasis].

The use of diuretics leads to a negative sodium and fluid balance without primary effects on serum sodium concentration. This parameter is regulated by the activity of the antidiuretic hormone (ADH) system. Secondary changes in other electrolyte systems and in acid base homeostasis also are induced by diuretic therapy. Especially diuretic induced hypokalemia is important as it is responsible for the excess mortality observed in patients with diuretic treated essential hypertension and cardiac abnormalities. All adverse metabolic effects of diuretic therapy are, in contrast to the antihypertensive action, dose dependent. Changes in fluid and electrolyte metabolism induced by diuretics occur within the first 2 or 3 weeks after initiation of medication. Counterregulatory mechanisms are activated and a new steady state is established. Serial laboratory determinations after this period are not necessary as long as this steady state is not affected by additional events (like a change in therapy or diet as well as the occurrence of vomiting or diarrhea).

Acid-Base Equilibrium↗
PubMed1996

[Renal side effects of angiotensin converting enzyme inhibitors].

Angiotensin converting enzyme (ACE) inhibitors are used widely in the treatment of hypertension and congestive heart failure. An increasing number of patients with chronic renal failure is treated with ACE inhibitors because of their antiproteinuric effect. In patients with diabetic nephropathy ACE inhibitors also slow the progression of renal failure. Direct drug related nephrotoxic effects, like the induction of proteinuria, glucosuria or an interstitial nephritis are rare events. The often observed reduction of the glomerular filtration rate after the induction of an ACE inhibitor therapy is due to the specific intrarenal action of these agents and therefore not an adverse drug reaction.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Effects of vitamin B12 on human circadian body temperature rhythm.

To clarify the effect of vitamin B12 on the human circadian clock, five healthy male adults participated in two constant routine procedures, 2 or 3 weeks apart. In one, subjects received intravenous saline injections (placebo trial) and in the other, intravenous injections of methylcobalamin (MB12) (drug trial). Intravenous administration of MB12 increased rectal temperature in the later hours of the daytime during the constant routine. The activity did not change between treatments in any period during the constant routine. During the later hours of the constant routine, alertness assessed with visual analog scale was higher in the drug trial than in the placebo trial. The period in which drug treatment produced greater alertness almost coincided with that in which MB12 elevated rectal temperature. These results may provide evidence of an effect of vitamin B12 on the circadian clock.

Adult↗
PubMed1995

Elevated levels of serum carbohydrate deficient transferrin are not specific for alcohol abuse in patients with liver disease.

BACKGROUND: Serum carbohydrate deficient transferrin is a marker of chronic alcohol consumption; it increases above normal in healthy individuals after a daily alcohol intake of more than 60 g/d for more than 2 weeks. The influence of liver disease itself on carbohydrate deficient transferrin levels has not been sufficiently established. METHODS: We investigated serum levels of carbohydrate deficient transferrin in 196 consecutive patients admitted to our Gastroenterology and Hepatology Unit and correlated this parameter with the patients' statements about alcohol intake during the previous 2 weeks and with other markers of chronic alcohol consumption. RESULTS: In our patient population, carbohydrate deficient transferrin had the best overall performance with respect to sensitivity (88%), specificity (82%), and negative predictive value (98%), as compared to other markers, although specificity was much lower than previously reported in patients without liver disease. In the group of patients with liver disease, sensitivity and specificity were 90% and 73%, respectively, and in patients without liver disease, 80% and 88%. The negative predictive value was excellent (96% for patients with liver disease and 99% for patients without liver disease). CONCLUSIONS: Thus, in a patient with a negative interview for chronic alcohol abuse and normal carbohydrate deficient transferrin level, alcohol is unlikely to be the cause of liver disease, and further investigations to establish the etiology of liver disease are warranted. An increased carbohydrate deficient transferrin level, however, cannot be regarded as reliable evidence for chronic alcohol abuse in patients with liver disease.

Adolescent↗
PubMed1995

No association of converting enzyme insertion/deletion polymorphism with immunoglobulin A glomerulonephritis.

It has been recently reported that in type 1 diabetes the insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme gene is associated with the presence of diabetic nephropathy. Tissue angiotensin I-converting enzyme is determined by I/D polymorphism, and it has been speculated that in diabetes differences of local angiotensin II availability determine the risk of renal disease. Since angiotensin II is thought to play an important role in the evolution of renal disease in general, we tested whether genotype distribution of the I/D polymorphism is also different in patients with immunoglobulin A-glomerulonephritis (IgA-GN). Furthermore we compared IgA-GN patients with (1) stable renal function or (2) terminal renal failure to investigate a potential role of the I/D polymorphism in the renal prognosis. We examined 122 patients with biopsy-confirmed IgA-GN who had stable renal function and 82 dialysis-dependent or transplanted patients with biopsy-confirmed IgA-GN. Furthermore, in 134 healthy individuals used as controls we analyzed the DNA for normal distribution of genotypes and allele frequencies. The polymorphic region was amplified using polymerase chain reaction with specific primers. Alleles were detected on 2% agarose gels. Genotype distributions and allele frequencies were not significantly different between controls and patients with IgA-GN and stable renal function. Furthermore, no significant difference in genotype distribution was detected between patients with IgA-GN and stable renal function compared with patients with IgA-GN and end-stage renal failure, although a trend for a higher frequency of DD-homozygotes was noted in the latter group (P = 0.07).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Effect of modafinil in narcoleptic patients. Electrophysiologic and psychometric studies].

Clinical efficiency of Modafinil was clearly demonstrated in narcoleptic patients but only a few electrophysiological studies were carried out to confirm these observations. Since Modafinil did not change the propensy to fall asleep, the aim of this work was to study maintenance of wakefulness and performance levels in treated narcoleptic patients. Of the 16 treated patients, 12 responded as expected to Modafinil. These 12 patients were studied. After a one night polysomnography, electrophysiological tests included: baseline spectral analysis, maintenance of wakefulness tests carried out respectively eyes open in diffused light and eyes closed in darkness during which sleep latency, duration of test and changes in the theta/alpha ratio were measured. Psychometric performances were evaluated using verbal or non verbal tests: visual and auditory reaction time tests. Trail Making Test, Stroop, verbal Fluency and WAIS-R. Modafinil improved the ability of narcoleptic patients to remain awake only when the situation or the environmental conditions were favorable. Some psychometric performances also trended towards on improvement.

Adult↗
PubMed1995

Lower cardiac troponin T levels in patients undergoing cardiopulmonary bypass and receiving high-dose aprotinin therapy indicate reduction of perioperative myocardial damage.

Nowadays in many European heart centers the activation of the fibrinolytic system, always occurring during cardiopulmonary bypass, is routinely reduced by high-dose application of the proteinase inhibitor aprotinin (total of > 4 million KIU). In this study parameters of myocardial ischemic injury were investigated with the aim of identifying further benefits of aprotinin, particularly the protection of the myocardium during the ischemic period of aortic crossclamping. Forty patients with coronary artery disease who underwent aorta-coronary bypass grafting were randomly and in a double-blind fashion divided into two groups, one that received high-dose aprotinin therapy and one that received only saline solution. Markers such as troponin T, with high specificity for detection of myocardial ischemia and infarction, and markers with more general specificity such as creatine kinase, its isoenzyme, and lactate dehydrogenase showed significantly increased values after ischemia in both groups. In patients who received high-dose aprotinin therapy 3 days after cardiopulmonary bypass all parameters measured showed significantly lower levels compared with those in the control group. Therefore we can presume that the application of high-dose aprotinin provides myocardial protection from perioperative ischemic injury.

Aprotinin↗
PubMed1995

Aprotinin in elective primary bypass surgery. Graft patency and clinical efficacy.

The proteinase inhibitor aprotinin is used in open heart surgery to reduce intraoperative and postoperative blood loss and transfusion requirements. To investigate a possible influence on graft patency, a randomized double-blind group comparison study was carried out in male patients elected for primary bypass surgery. One hundred ten (55/55) patients received either placebo treatment or aprotinin according to the Hammersmith scheme (2 Mio KIU as loading dose before sternotomy, followed by an infusion of 0.5 Mio KIU/h until the end of surgery; 2 Mio KIU added to the priming volume additionally). Graft patency was evaluated by angiography in 44 aprotinin and 35 placebo patients between the 18th and 35th days postoperatively. There was no difference in the overall graft occlusion: in the aprotinin group 89.5% (111/124) grafts were found patent compared to 87.2% (89/102) in the placebo group. Of the aprotinin patients 72.7% (32/44) and 71.4% (25/35) of the placebo patients had all grafts patent. Venous grafts were occluded in 16% (7/44) of aprotinin patients and in 29% (10/35) of placebo patients. On the other hand 5/27 patients in the aprotinin group vs 0/27 in the placebo group had occluded internal mammary artery (IMA) grafts (P = 0.0511%). Graft occlusions were not accompanied by signs of myocardial infarction in any case. Fifty-one patients in the aprotinin group and 47 patients in the placebo group were valid for parameters of clinical efficacy: blood loss within 6 h postoperatively was reduced by 58.5% in the aprotinin group (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗