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Biomedical subjects

G Mayer

Publications and source records attributed to G Mayer.

At least 181 records · Page 10Linked to original sources
PubMed1994

[The significance of quantitative computerized tomography in the long-term prognosis of ischemic stroke].

The courses of 118 patients who had suffered a supratentorial ischaemic infarction were observed over a mean follow-up period of 4 years. One goal of this study was to assess the prognostic value of quantitative cranial computerized tomography (CT). The infarct volume was determined using CT and expressed quantitatively as a percentage of the total brain volume. The infarct volume correlated negatively with the global outcome as estimated by the Barthel Index. It correlated positively with the occurrence of psychiatric alterations, disturbances of consciousness or alterations in the EEG. Nicotine, alcohol consumption and hyperuricaemia were the most frequent risk factors identified for men, while for women, especially those over 60, cardiac diseases were the most relevant risk factors. In looking only at the older patients, age, psychiatric alterations and cardiac disease at the time of the stroke were unfavourable prognostic factors. CT lesions in the basal ganglia were also unfavourable prognostic factors. Infarcts in the posterior cerebral artery region were seen as prognostically favourable. During the 4-year follow-up period, the reinfarction rate was 26%. Nearly 50% of the total patient population died. This group was significantly older, had more psychiatric alterations as well as multiple infarct areas in CT.

Adolescent↗
PubMed1994

[Demonstration of platelet-specific alloantibodies in HLA-sensitized hematologic oncologic patients].

Alloimmunization to the platelet-specific antigen systems HPA-1, -3 and -5 was studied in 59 multitransfused patients (31 females, 16 males, 12 children) with haematologic-oncologic disorders. All patients tested had broad-reacting or multispecific HLA antibodies. Of these, 10 (17%) were found to have additional platelet-specific alloantibodies. With respect to HLA sensitization, 9 out of 10 platelet-specific alloantibodies were found in sera which showed HLA antibodies reacting with more than 95% of unselected panel cells. Determination of antibody specificity revealed 6 patients with anti-HPA-1b, one patient with anti-HPA-3a, and 2 patients with anti-HPA-1b combined with anti-HPA-3a. One patient had anti-HPA-5b; in retrospect, only the HPA-5b antibody was demonstrable before the beginning of transfusion therapy and before HLA sensitization.

Adult↗
PubMed1993

Beneficial effect of autologous blood transfusion on infectious complications after colorectal cancer surgery.

Homologous blood transfusion has been associated with an increased risk of postoperative infectious complications. To test the clinical consequences of this apparently immunosuppressive effect of homologous blood in a controlled trial, we designed a study in which the control group deposited autologous blood before their operations for use should transfusion be needed. We enrolled 120 patients with apparently curable colorectal cancer who were able to predeposit autologous blood (haemoglobin > 12.5 g/dL). 62 patients were assigned to receive homologous blood if blood transfusions were needed during operation, and the other 58 to receive their own predeposited blood followed, if necessary, by homologous blood [corrected]. Despite the similarity between the groups in factors known to affect the risk of postoperative infections, there was a significant difference in postoperative infection rate between the homologous and autologous blood groups (17 [27%] vs 7 [12%], p < 0.05; unadjusted odds ratio 2.75 [95% CI 1.07-7.11). The rates of non-infectious complications were similar Probably because their preoperative blood depositing caused the autologous blood patients to have lower haemoglobin concentrations, they were more likely to require transfusion than were the homologous blood group (53 [91%] vs 37 [60%], p < 0.001; relative risk 1.53 [1.24-1.89]). 20 (35%) required homologous as well as autologous blood. To adjust for the many infection-related factors, we did multivariate regression analysis; tumour location, preoperative ASA index, and study group assignment were the only significant risk factors. The odds ratio for postoperative infections adjusted for these factors was 2.84 (1.02-7.98, homologous vs autologous). Testing of delayed-type hypersensitivity responses before and after surgery showed decreases in both mean diameter and number of positive reactions in recipients of homologous blood and slight increases in those who received autologous blood. This study shows the clinical potential of blood-transfusion-mediated immunomodulation, which may be important also in tumour immunology.

Adenocarcinoma↗
PubMed1993

[Cervico-mediastinal goitre. Analysis of preoperative clinical symptoms].

During past decades, a considerable and debated speculation about the classification of intrathoracic goitre was more and more developing. One of the most reliable classifications we share is that considering the degree of the intrathoracic extension of the thyroid gland: i) largely intrathoracic (more than 80%), ii) partially intrathoracic (more than 50%, but less than 80%), and iii) sub-sternal goitre (more than 50% holding in the neck). Consistently with the above mentioned classification, this report deals with ninety-seven cases of completely intrathoracic goitre (64 females and 33 males, aging between 29 and 78 years). Sixty-eight patients out of these showed a goitre reaching the upper aortic border; the other 29 patients had a thyroid gland exceeding this degree of extension. Therefore the intrathoracic goitre is a not frequent thyroid disease: in our series, it represents the 3.67% of 2641 surgical interventions on the thyroid gland from January 1984 to December 1990, that is to say the 20% of the so-called plongeant goitres undergoing surgery during the same years. The aim of this survey was to study the clinical features of the intrathoracic goitre and to have a therapeutic and prognostic assessment in this thyroid disease, before the surgical intervention. To this purpose, the prodromic symptom or sign, the clinical course before surgery, the clinical examination (peculiarly about the neck) and the laboratory findings at admission, the preoperative imaging study (chest X-ray, ultrasound examination, scintiscan and tomoscan finding) were reviewed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Effects of dichloroacetate on exercise performance in healthy volunteers.

Dichloroacetate (DCA), a stimulator of the pyruvate dehydrogenase complex, decreases lactate levels and peripheral resistance and increases cardiac output. This study was performed to examine the effects of DCA on exercise performance in humans. Eight healthy male volunteers (age 20-28 years) were tested by bicycle spiro-ergometry using a microprocessor-controlled gas analysis system after infusion of DCA (50 mg/kg body weight) or saline. Prior infusion of DCA significantly reduced the increase of lactate levels during exercise when compared with infusion of saline (1.40 +/- 0.21 vs 2.10 +/- 0.09 mmol.l-1 at 50% of the expected maximal working capacity, P < 0.05; 8.53 +/- 0.45 vs 9.92 +/- 0.59 mmol.l-1 at maximal working capacity, P < 0.05). Oxygen uptake increased significantly after DCA when compared with saline from 7.5 +/- 0.4 vs 7.4 +/- 0.5 to 27.2 +/- 1.5 vs 23.7 +/- 1.7 (P < 0.05) at anaerobic threshold and to 35.6 +/- 1.7 vs 30.5 +/- 1.0 ml.kg-1 min-1 (P < 0.05) at maximal exercise capacity. Following DCA infusion the workload at which the anaerobic threshold was reached was significantly higher (160 +/- 7 vs 120 +/- 5 W, P < 0.05) and the maximal working capacity was significantly increased (230 +/- 9 vs 209 +/- 8 W, P < 0.05). In summary, DCA reduced the increase of lactate levels during exercise and increased oxygen uptake at the anaerobic threshold and at maximal working capacity, which was significantly increased. These results warrant further studies on a potential therapeutic application of DCA in patients with reduced exercise capacity.

Adult↗
PubMed1993

Effects of angiotensin II receptor blockade on remnant glomerular permselectivity.

This study examined the mechanisms by which angiotensin II (Ang II) receptor blockade improves glomerular barrier function in rats with reduced nephron number. Proteinuria was measured at four weeks after 5/6 renal ablation, and rats were then divided into a group which received the Ang II receptor blocker MK954 and a group which received no treatment. Studies performed one week later showed that Ang II receptor blockade reduced proteinuria without altering GFR in renal ablated rats. Micropuncture studies showed that Ang II blockade reduced both mean arterial pressure (142 +/- 7 mm Hg, ablation without treatment; 105 +/- 2 mm Hg, ablation with treatment) and glomerular transcapillary pressure (54 +/- 3 mm Hg, ablation without treatment; 43 +/- 1 mm Hg, ablation with treatment). Dextran sieving studies showed that untreated rats developed a size-selective defect characterized by increased transglomerular passage of neutral dextrans with radii 54 to 76 A and a charge-selective defect characterized by an increased transglomerular passage of anionic dextran sulfate with a radius of approximately 18 A. Ang II blockade reduced fractional clearance values for large neutral dextrans near to values observed in normal rats but had no effect on the fractional clearance of dextran sulfate (0.68 +/- 0.11, ablation without treatment; 0.66 +/- 0.08, ablation with treatment; 0.46 +/- 0.05, normal rats). These findings indicate that reducing Ang II activity improves size-selectivity without affecting charge-selectivity in injured remnant glomeruli.

Angiotensin II↗
PubMed1993

The effects of lisinopril on renal function in proteinuric renal transplant recipients.

Renal transplantation is frequently accompanied by systemic hypertension. In the present study we evaluated the effect of 2.5 mg lisinopril in 12 hypertensive and proteinuric renal graft recipients with stable graft function over 3 months. Only patients with absence of renal artery stenosis, at least as judged by technetium-scan imaging, were included. Lisinopril was effective in lowering systemic blood pressure. Mean arterial pressure was unchanged despite reduction of concomitant antihypertensive medication. Mean serum creatinine was unchanged during the study (1.95 +/- 0.8 mg/dl in the pretreatment period vs. 1.77 +/- 0.76 mg/dl in the intervention period, n.s.). Glomerular filtration rate remained stable (62.75 +/- 21.96 vs. 60.17 +/- 18.27 ml/min/1.73 m2, n.s.) whereas renal plasma flow increased (224.75 +/- 91.66 vs. 244.92 +/- 94.13 ml/min/1.73m2, P < 0.01), leading to a drop in filtration fraction (31.4 +/- 12.4 vs. 26.8 +/- 8.6, n.s.). Renal vascular resistance was significantly reduced following angiotensin-converting enzyme (ACE) inhibitor therapy (26,447 +/- 14,574 vs. 23,425 +/- 12,430 dyne sec cm-5/1.73 m2, P < 0.01). Mean daily proteinuric decreased significantly (2.98 +/- 2.06 vs. 2.06 +/- 2.29 g, P < 0.01) whereas in a group of patients with comparable blood pressure but without ACE inhibitor therapy and similar degree of proteinuria, 24-hr proteinuria remained stable. No severe side effects were observed--in particular, mean serum potassium showed only a slight increase and no clinically significant hyperkalemic condition was observed. When lisinopril therapy was withdrawn after 3 months, blood pressure increased in all patients, requiring reinstitution of additional antihypertensive medication. Renal hemodynamic parameters and daily proteinuria returned to baseline values. We conclude that 2.5 mg lisinopril daily was safe and effective in this group of renal transplant recipients and showed a good antihypertensive as well as antiproteinuric effect.

Adult↗
PubMed1993

Motor dyscontrol in sleep of narcoleptic patients (a lifelong development?).

In our retrospective study 27 narcoleptic patients were divided into two groups: Group A comprised 14 patients (10 male, 4 female) with a history of REM behaviour disorder (RBD) and Group B comprised 13 age- and sex-matched patients (10 male, 3 female) without a history of RBD. Polygraphic and videometry data, medical history, medication, blood chemistry, psychological and neuroradiological data of the two groups of patients were compared. The narcoleptic patients with a history of RBD differed from the narcoleptic control group without history of RBD in that they had: (a) a higher frequency of parasomnias in their history; (b) a higher percentage of stage 1 REM (P < 0.01); (c) a lower number of arousals during REM sleep; (d) fewer sleep stage changes. Compared to the heterogenous RBD patient group of Mahowald and Schenck, the REM behaviour of most of our narcoleptic patients was less violent. Thus it can be speculated that the motor disorder in REM sleep might still be in the process of developing towards a full-blown REM sleep behaviour disorder. In a possible lifelong development of a motor disorder starting in NREM sleep, the onset of narcolepsy might represent the turning point for its intrusion into REM sleep.

Journal Article↗
PubMed1993

Treatment of narcolepsy-cataplexy syndrome with the new selective and reversible MAO-A inhibitor brofaromine-a pilot study.

Eighteen narcoleptic patients were treated in a single-blind study with brofaromine, a new selective and reversible MAO-A-inhibitor. After a drug-free period of seven days, brofaromine was administered for two weeks. Patients were treated with 75 mg brofaromine for the first week and with 150 mg brofaromine for the second week of the study. After an adaptation night nocturnal sleep EEGs were recorded under placebo before brofaromine was given, one week later under 75 mg, and another week later under 150 mg brofaromine. Excessive daytime sleepiness (EDS) was evaluated under placebo at the beginning of the study, under 75 mg at the end of the first week, and under 150 mg brofaromine at the end of the second week by means of the Multiple Sleep Latency Test (MSLT) and the Maintenance of Wakefulness Test (MWT). The number of cataplexies was protocolled by the patients. Compared to placebo the administration of 150 mg brofaromine led to a significant increase of sleep latency in the MLST as well as in the MWT. REM sleep was significantly suppressed in the nocturnal sleep EEG, in the MSLT and in the MWT. The number of cataplexies protocolled by the patient was significantly decreased under 150 mg of brofaromine compared to placebo. Improvement of vigilance and cataplexy occurred in dose-dependent manner. No serious side effects were observed. The results of the present single-blind study indicate that brofaromine seems to be a well-tolerated and effective drug for the treatment of excessive daytime sleepiness and cataplexy in narcoleptic patients.

Journal Article↗
PubMed1993

Serological screening, using three different test systems of platelet-transfused patients with hematologic-oncologic disorders.

Sera of hematologic-oncologic patients were tested regularly after platelet transfusions in three test systems: lymphocytotoxicity test, platelet adhesion immunofluorescence test, and--only selected sera--in the monoclonal antibody-specific immobilization of platelet antigen test. Of 388 patients 53 (14%) had HLA antibodies 5 of these in combination with platelet-specific alloantibodies. Lymphocyte-restricted (non-HLA) reactions were observed in 20 patients, the majority of which was attributed to lymphocyte-specific auto- or alloantibodies. Sera of 27 patients showed platelet-specific reactions, usually cold-reacting autoantibodies which have no effect in vivo.

Adult↗
PubMed1993

Glomerular permeability barrier in the rat. Functional assessment by in vitro methods.

The formation of glomerular ultrafiltrate is dependent on the prevailing hemodynamic forces within the glomerular microcirculation and the intrinsic properties of the filtration barrier. However, direct assessment of the permeability barrier is difficult with most available techniques. We used confocal microscopy to image 1-micron thick optical cross-sections of isolated intact glomeruli and glomeruli denuded of cells and quantitated dextran (70,000 mol wt) diffusion from the capillary lumen. Dextran permeance was 11 times greater for the acellular filtration barrier than the intact peripheral capillary. Consideration of the basement membrane and cells as series resistors demonstrated that cells of the filtration barrier contribute 90% of the total resistance to macromolecular permeance. Using a different approach, dextran sieving coefficients for acellular glomeruli consolidated as a multilayer sheet in a filtration cell were similar to those for intact glomeruli in vivo at radii 30-36 A and approximately 50 times greater at a dextran radius of 60 A. The presence of cells significantly reduced hydraulic permeability determined on consolidated intact or acellular glomeruli in an ultrafiltration cell with 50 mmHg applied pressure. The glomerular basement membrane does restrict macromolecular permeability but cells are important determinants of the overall macromolecular and hydraulic permeability of the glomerulus.

Animals↗
PubMed1993

The effects of blood pressure reduction on cyclosporine nephrotoxicity in the rat.

The effects of blood pressure reduction on cyclosporine nephrotoxicity were studied over 12 months in four groups of rats. Group 1 received no drugs and served as controls. Groups 2, 3, and 4 received cyclosporine (CyA), approximately 9 mg/kg.day, in their food. In addition, Group 3 received enalapril and Group 4 received minoxidil, hydrochlorothiazide, and reserpine. Time-averaged monthly systolic blood pressure was equal in Groups 1 and 2 (136 +/- 1 and 135 +/- 1 mm Hg, respectively). Antihypertensive agents reduced average systolic blood pressure in Groups 3 and 4 (116 +/- 1 and 117 +/- 1 mm Hg, respectively). Morphometric studies showed that 12 months of CyA treatment caused interstitial fibrosis with an increase in the fractional volume of cortical interstitium (VvInt: Group 2, 20 +/- 1%; Group 1, 11 +/- 1%) and a reduction in mean glomerular volume (VG. Group 2, (2.00 +/- 0.06) x 10(6) mu 3; Group 1, (2.48 +/- 0.06) x 10(6) mu 3). These structural changes were accompanied by a significant reduction in GFR (Group 2, 2.27 +/- 0.10 mL/min; Group 1, 2.76 +/- 0.10 mL/min). Cotreatment with enalapril reduced interstitial fibrosis (VvInt, 14 +/- 1%) and maintained VG (2.23 +/- 0.08 x 10(6) mu 3) and GFR (2.56 +/- 0.08 mL/min) at near-normal values in Group 3. In contrast, the combination antihypertensive regimen increased the extent of interstitial fibrosis (VvInt, 24 +/- 1%) and further lowered VG (1.72 +/- 0.05 x 10(6) mu 3) and GFR (1.72 +/- 0.05 mL/min) in Group 4. These results show that sustained treatment with a moderate dose of CyA causes interstitial fibrosis and impairs renal function in rats. The administration of enalapril, but not minoxidil, reserpine, and hydrochlorothiazide, limits renal injury in this model.

Animals↗
PubMed1993

[Assessment of the degree of disability in narcolepsy].

This article sums up the scientific results of the past 10 years on narcolepsy reflecting its impact on socio-medical impairment of narcoleptic patients. Extensive epidemiological studies showed that major restrictions for narcolepsy patients are caused by daytime sleepiness and sleep attacks with consecutive cognitive and memory deficits high accident rates, personality, mood and sexual disorders. We suggest the minimum degree of impairment as a rule should be at least 50%, in case of drug-resistant cataplexy or permanent sleep attacks around 80%.

Cataplexy↗
PubMed1992

Streptomycin biosynthesis and its regulation in Streptomycetes.

New insights into the gene orders, structures, evolution, and functions of streptomycin (Sm) biosynthetic genes (str) were gained via hybridization studies, determination of nucleotide sequences, and measurement of expression in the str gene clusters of Streptomyces griseus and S. glaucescens. Both str clusters showed considerable divergence in macro and micro structure. Genes putatively involved in pathways leading to the (dihydro-)streptose and N-methyl-L-glucosamine moieties of Sm were identified. Additional regulatory elements, such as gene strS and conserved TTA codons in the N-terminal sections of reading frames, are reported. Evidences for the involvement of physiological state, signal transduction, and activators in the control of Sm production are presented.

Bacterial Proteins↗
PubMed1992

[Clinical and immune hematologic problems in prenatal prevention of Rhesus sensitization].

Various studies have provided impressive evidence of the efficacy of antenatally administered anti-D in the prevention of rhesus (D) alloimmunisation in rhesus-negative women. However, possible clinical and immunohaematological problems associated with this prophylactic therapy have received little attention. We describe perinatal and immunohaematological problems, which occurred in four cases after antenatal rhesus prophylaxis. Classical immunohaematological techniques were employed, to detect and specify irregular red cell antibodies. It was found, that the antenatal administration of anti-D could mask sensitization to other red cell antigens or the production of maternal immune anti-D antibodies later in pregnancy. A further problem encountered was that of neonates with a positive direct Coombs' test (the uncertainty in the individual case being, whether this is a result of the antenatal administration of anti-D) and marked hyperbilirubinaemia. Antenatal immunoprophylaxis for rhesus disease can give rise to immunohaematological and clinical findings, of which the interpretation is extremely difficult and requires intensive cooperation between the obstetrician, neonatologist, and haematologist/clinical biochemist.

Adult↗
PubMed1992

Isoagglutinins following ABO-incompatible bone marrow transplantation.

Isoagglutinins were investigated following ABO-incompatible bone marrow transplantation. In major incompatibility anti-A tends to require more time to disappear than anti-B. Correspondingly, A erythrocytes require more time to become demonstrable. There is no such difference in major plus minor incompatibility. In minor incompatibility, isoagglutinins against the recipient blood group may be produced early after bone marrow transplantation, which then give way to a possibly lifelong tolerance for the recipient's old blood group.

ABO Blood-Group System↗