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Biomedical subjects

D Nagel

Publications and source records attributed to D Nagel.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Electrostimulation-induced stapedius reflex. Presentation of a standardized procedure and results of clinical studies].

The electro-tactile elicitation of the stapedius muscle reflex is well known but not used in clinical practice. Despite a complex reflex pathway in the brainstem, correlations between reflex parameters and neurological impairments are still possible. We have developed a method for eliciting the electro-tactile stapedius muscle reflex and automatic analysis of different reflex parameters by using an analog-digital converter and a personal computer-integrated signal analysis system. Clinical investigations were carried out with a group of 55 healthy persons (control group), 13 patients with central facial palsies, 51 patients with multiple sclerosis (MS group) and 24 patients with absent acoustic-stapedius muscle reflexes. Findings demonstrated that the latency between stimulus and beginning of the reflex (L1) was significantly longer in the MS group compared with the control group. The best parameter for dividing the MS group into groups with different disability scores was S, which was the parameter for the increase in the L1 growth curve at different stimulus levels. Reproduction of the parameter S in repeated tests with different locations of the stimulus-electrode was excellent.

Brain Damage, Chronic↗
PubMed1994

Lipoprotein Lp(a) as predictor of myocardial infarction in comparison to fibrinogen, LDL cholesterol and other risk factors: results from the prospective Göttingen Risk Incidence and Prevalence Study (GRIPS).

Based on pathophysiological findings Lp(a) is considered to be a cardiovascular risk factor. The Göttingen Risk Incidence and Prevalence Study (GRIPS) provides the possibility to evaluate this impact of Lp(a) on the basis of a large prospective cohort study. GRIPS included 6002 men, aged 40-59.9 years at baseline. Data of a 5 year follow-up period is now available for > 95% of the study participants. Multivariate logistic regression models for the estimation of MI risk confirm Lp(a) as an important risk factor, ranking fifth behind LDL cholesterol, family history of MI, plasma fibrinogen and HDL cholesterol (inversely related). The GRIPS data strongly support strategies for the identification and treatment of persons at increased MI risk which focus on LDL cholesterol. However, Lp(a) and fibrinogen have to be seriously considered as additional risk factors and should be included in diagnostic panels for the estimation of MI risk.

Cholesterol, LDL↗
PubMed1994

Endothelin and atrial natriuretic peptide in non-insulin-dependent diabetic versus nondiabetic patients on chronic hemodialysis.

Plasma levels of endothelin (ET) and atrial natriuretic peptide (ANP) are known to be elevated in patients on chronic hemodialysis. Since ET and ANP plasma levels are found to be raised in nonuremic diabetic versus nondiabetic subjects, we wanted to detect a possible difference in plasma levels of these hormones in diabetic versus nondiabetic patients who were on chronic renal replacement therapy. ET is a possible marker of increased vascular atherogenic activity. We measured plasma levels of ET and ANP pre- and posthemodialysis in 23 non-insulin-dependent (NIDDM) diabetic versus 23 nondiabetic patients who were matched according to age and time of day of hemodialysis, and who did not show clinical signs of overt cardiac decompensation. Mean plasma levels of ET and ANP did not differ in diabetic from nondiabetic patients, neither pre- nor postdialysis. In both patient groups, mean ET levels were twice the upper normal limit, did not change significantly pre- versus postdialysis, and did not correlate with blood pressure or with volume ultrafiltration during dialysis. Calcium channel blocker therapy was accompanied by a significant rise of ET pre- and postdialysis in nondiabetic patients but not in diabetic patients. In diabetic patients, ET plasma levels correlated positively with fructosamine levels as an indicator of short-term blood glucose control. Mean ANP plasma levels were about three times the upper normal limit and decreased significantly during dialysis, but this decrease correlated neither with volume ultrafiltration nor with blood pressure. In conclusion, we could not find a difference in plasma levels of ET and ANP for diabetic versus nondiabetic dialysis patients, but impaired short-term blood glucose control in diabetic and calcium channel blocker therapy in only nondiabetic dialysis patients showed concomitant increases in plasma ET levels and thus possibly different mechanisms of ET regulating pathways.

Aged↗
PubMed1993

CYFRA 21-1. A new marker in lung cancer.

BACKGROUND: It is known that cytokeratin 19 is particularly abundant in carcinoma of the lung. METHODS: A sandwich enzyme-linked immunosorbent assay called CYFRA 21-1 was, therefore, developed to detect soluble cytokeratin 19 fragments in serum using two specific monoclonal antibodies (Ks 19.1 and BM 19.21). The authors investigated the clinical significance of this new marker compared with the established markers carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC), neuron-specific enolase (NSE), carbohydrate antigen (CA) 19-9, CA 125, CA 15-3, CA 72-4, alpha-fetoprotein, and prostate-specific antigen in a pilot study on 1741 serum samples from patients with various benign and malignant diseases. RESULTS: Postulating a specificity of 95% versus benign diseases of the lung, the diagnostic sensitivity of CYFRA 21-1 in lung cancer (independent of histologic type) at primary diagnosis was superior (47%) to CEA (27%), SCC (15%), and NSE (16%). Especially in squamous cell carcinomas of the lung, the true-positive test results were much higher for CYFRA 21-1 (60%) than for CEA (18%) or SCC (31%). CONCLUSIONS: In small cell lung carcinomas, NSE was confirmed as the marker of first choice. For all of the other solid tumors investigated, CYFRA 21-1 showed no better profile of specificity and sensitivity than the established markers.

Antibodies, Monoclonal↗
PubMed1993

Auditory reflex thresholds elevated by stress-induced cortisol secretion.

To study steroid effects on auditory perception, 24 volunteers were unexpectedly confronted with a psychological stressor. Auditory reflexes to pure tones and noise were recorded before stress exposure, up to 100 min afterwards and in a second control session. Repeated measurements of cortisol and testosterone in saliva, as well as blood pressure, heart rate, and subjective feelings confirmed the stressful nature of the test. Following stress induction the auditory reflex of the contralateral ear needed significantly higher loudness (i.e. more decibels) to be elicited than at baseline or control measures. Two lines of evidence suggest that this stress-induced change may be specifically related to glucocorticoid actions: (1) In a previous study similar elevations in auditory reflex threshold had been obtained by the administration of exogenous glucocorticoids (hydrocortisone), and (2) in the present study the overall effect of stress induction on acoustic reflex described above was mainly observed in a subgroup of subjects, who responded to the stressor with a marked rise in free cortisol.

Acoustic Stimulation↗
PubMed1993

Development and evaluation of a reagent carrier with a new reaction sequence for the determination of creatinine in blood, plasma, serum and urine.

After a short outline of the history of creatinine determination methods we describe the development of a dry-reagent-carrier system for the reflometric determination of the creatinine concentration in blood, plasma, serum and urine (Reflotron Creatinine (new)). The method is based on a sequence of enzymatically catalyzed reactions producing H2O2, but which in contrast to the previously used procedure do not lead to the formation of creatine as an intermediate. Hence, pretreatment of sample material to eliminate endogenous creatine is no longer necessary. In the indicator reaction, use is made of an imidazole derivative as the chromogen. The dye formed in the presence of peroxidase can be measured by reflectance photometry beyond the long-wave absorption bands of haemoglobin and bilirubin at 642 nm. We present in detail the results of the multicentre evaluation of the analytical properties of this new test principle. The data obtained show that Reflotron Creatinine (new) correlates well with the routine method Creatinine PAP, which was used as a comparison method, with respect to accuracy and precision and even surpasses it with respect to specificity. Advantages over the first generation of Reflotron Creatinine are: shorter reaction time, longer stability of the reagent carrier, no interference by bilirubin and reduced interference by haemoglobin.

Blood Chemical Analysis↗
PubMed1992

Biochemical, hematological and endocrinological parameters during repeated intense short-term running in comparison to ultra-long-distance running.

In order to see the differences in the acute effects of two kinds of running on biochemical, hematological and hormonal parameters, we investigated in one 24 h race (same exterior conditions) two groups of runners (NR = nonstop runners; RR = relay runners). From each participant blood samples were taken before, 3 times during and after the race. In both groups the lipid parameters cholesterol, triglycerides and LDL-cholesterol declined significantly, triglycerides even to 40% of their initial value, whereas HDL-cholesterol increased significantly. Renal parameters showed similar increases in both groups except for uric acid, which rose by 73% in RR compared with only 23% increase in NR. A difference was also found in the lactate and glucose concentrations, showing a four-fold increase and a 34% increase at 4 h respectively in RR, whereas the NR remained constant. Changes in the hematological parameters were similar in both groups. Cortisol and prolactin showed similar alterations during the race but LH and testosterone declined to approximately half of their initial concentration (p greater than 0.05) in NR after 4 to 8 h, in contrast to RR, where the concentration of LH or testosterone remained constant or changed only moderately but insignificantly during the race. Our investigation indicates that in ultra-long-distance running and intense short-term exercise performed under the same exterior conditions, many parameters show similar changes but great differences can be found as well if certain hormones, glucose metabolism and renal parameters are considered.

Adolescent↗
PubMed1992

Removal of toxic metals and nonmetals from contaminated water.

The effects of the application of potassium ferrate to remove possible toxic compounds are presented. Potassium ferrate (K2FeO4) is shown in this work to be an effective means to remove toxic metals and nonmetals from aqueous solution. The toxic material present in water is precipitated from aqueous solution and readily removed. Potassium ferrate removes itself from solution. Discolored contaminated water may be made clear by utilizing potassium ferrate. In addition, turbidities of solutions induced by dissolved substances are eliminated by the action of potassium ferrate. The efficacy of potassium ferrate in cleaning contaminated water shows great potential in application to municipal and industrial waste water.

Chemical Precipitation↗
PubMed1992

Significance of bone alkaline phosphatase, CA 15-3 and CEA in the detection of bone metastases during the follow-up of patients suffering from breast carcinoma.

After the introduction (1, 2) and methodical evaluation (3, 4) of a new method for the quantitative measurement of the bone isoenzyme of alkaline phosphatase (test-combination bone alkaline phosphatase, Boehringer Mannheim), we started a retrospective clinical study for the follow-up investigations of breast cancer patients. Our aim was to establish the significance of the routinely used tumour markers, CEA and CA 15-3, in combination with bone alkaline phosphatase for the early detection of metastatic spread to the bone. We investigated 492 sera from 92 patients suffering from breast carcinoma, and we compared each date of investigation with the results of the clinical examination and with the results of medical imaging, if that had been performed. From a previous study involving skeleton scintigraphy (5) we knew that single examinations do not allow a differential diagnosis between benign and malignant disorders of the bone, so we based our calculations on differences between sequential investigations. We found that in follow-up investigations of patients with breast carcinoma the combined determination of CEA, CA 15-3 and bone alkaline phosphatase may be indicative for the localisation of metastatic disease. The determination of the bone alkaline phosphatase is easy to handle with a short assay time and good reproducibility; it can therefore be recommended.

Alkaline Phosphatase↗
PubMed1992

Cluster analysis in diagnosis.

The purpose of this paper is to survey the usefulness of cluster analysis in the special case of diagnoses. This complex topic is restricted, however, to the application on laboratory characteristics, separately or in connection with clinical data. The article is subdivided into three parts: (a) the fields of a possible use of cluster analysis, detection of diseases or subgroups of diseases, and data reduction by detection of structures; (b) a brief mathematical description of hierarchical and partitioning classification techniques (as a crucial point, the problems associated with these methods are discussed); (c) a critical review of 24 publications of the past 10 years concerning cluster analysis and diagnoses.

Clinical Laboratory Techniques↗
PubMed1991

Histologic, biochemical, and clinical parameters for monitoring multiple myeloma.

In a retrospective and prospective follow-up study from 1968 to 1989, bone marrow biopsy specimens, serum beta-2-microglobulin (SB2M) levels, and the clinical features of 251 patients with multiple myeloma (MM) and 28 patients with monoclonal gammopathy of undetermined significance (MGUS) were investigated. The main histologic variables (tumor cell type, tumor growth, tumor load, and fibrosis), SB2M level, serum thymidine kinase (STK) level, and various clinical parameters were analyzed to determine factors of value in monitoring the clinical phases of activity in MM. Our recently proposed prognostic strategy combining bone marrow histologic type, SB2M level, and signs of organ failure was tested for its ability to (1) diagnose the early and smoldering variants; (2) facilitate decisions on the time of initiation, the type and duration of initial induction therapy in the pretreatment phases (active and rapidly progressive phases); and (3) characterize variations in tumor regression and tumor-host interactions during chemotherapy (early treatment, plateau, relapse, transition, and refractory phases). The results indicate that this clinicopathologic monitoring combines information both on stage and aggressivity of MM and thus facilitates therapeutic decisions in the various clinical phases of MM.

Biomarkers, Tumor↗
PubMed1991

Serum androgens in intensive-care patients: correlations with clinical findings.

Serum androgen levels were studied in 100 patients (50 male) with varying degrees of severe illness, determined by Acute Physiological and Chronic Health Evaluation (APACHE). Comparison with normal subjects revealed the following changes: (1) Basal dehydroepiandrosterone sulphate (DHEAS) values were decreased in the ill female patients (P less than 0.001) as well as in the ill males (two groups, P less than 0.01; P less than 0.05). Androstenedione values did not differ from the controls in patients of either sex. Basal testosterone levels were decreased in ill male patients (P less than 0.001), but not in females. (2) The low testosterone concentrations in the severely ill male patients correlated inversely with the APACHE score; additionally, a dependence on diagnostic categories could be demonstrated in men, since the lowest values were found in patients suffering from sepsis or liver cirrhosis. Acutely ill males had a moderately decreased testosterone, whereas chronically ill males showed a marked reduction of testosterone compared to the controls. Lowered DHEAS and androstenedione levels could be measured in chronically ill males but not in ill females. (3) 17 alpha-OH-progesterone and 17 alpha-OH-pregnenolone levels in subgroups of the patients suggested a probable enzymatic block in the delta 5-pathway of androgen biosynthesis in severe illness. The ratio of 17 alpha-OH-pregnenolone to DHEAS was significantly higher in male patients and tended to be high in ill females, whereas the ratio of 17 alpha-OH-progesterone to androstenedione showed no difference between healthy and ill subjects.

17-alpha-Hydroxypregnenolone↗
PubMed1991

The kinetics of chemical reaction of activated nitrosamine with organic substrates.

The chemical reaction of tosylated N-nitrosobis (2-hydroxylpropyl) amine with aniline, 1-naphthol, pyridine, and hydroxylamine follows kinetics which can be described in a mixed order rate equation. This nitrosamine, considered an activated nitrosamine with a potential for alkylating a substrate, was seen to alkylate aniline, pyridine, 1-naphthol, and hydroxylamine. The presence of salts in the solution as well as an increase in solution pH increased the rate of reaction of the nitrosamine with substrates. The nitrosamine reacts quickly with water but will not react with solvents such as acetonitrile, dimethylsulfoxide, and methylene chloride.

Alkylating Agents↗
PubMed1991

Nitrosation of tertiary aromatic amines related to sunscreen ingredients.

Possible routes to the formation of the sunscreen contaminant, 2-ethylhexyl 4-N-methyl-N-nitrosoaminobenzoate, have been investigated in a study of the nitrosation chemistry of 2-ethylhexyl 4-N,N-dimethylaminobenzoate (Padimate-O) and related tertiary and secondary amines. Padimate-O and the corresponding ethyl ester nitrosate rapidly at 25 degrees C in either N2O3:ether or HNO2:HOAc to produce a mixture of alkyl 4-N-methyl-N-nitrosoaminobenzoate and alkyl 4-N,N-dimethylamino-3-nitrobenzoate, the former of which is the major product. The nitrosative dealkylation of these amines at this low temperature is unusual. Asymmetrical amines exhibit a preference for nitrosative demethylation (methyl versus ethyl or benzyl), but the cleavage ratios in N2O3:ether are time-dependent, suggesting competing mechanisms with different reactant kinetic orders. A radical cation route would explain the unusual reactivity, which may compete with the established nitrosative dealkylation mechanism. 2-Ethylhexyl 4-N-methyl-N-nitrosoaminobenzoate was mutagenic in two strains of Salmonella typhimurium in the Ames assay.

4-Aminobenzoic Acid↗
PubMed1990

The mutation of V79 cells by N-nitrosobis(2-oxopropyl)amine activated by pancreas acinar and duct tissue from Syrian hamsters and MRC-Wistar rats.

The mutagenicity of N-nitrosobis(2-oxopropyl)amine was measured in the V79 assay using homogenates of acinar cells and duct tissue from the pancreases of Syrian hamsters and MRC-Wistar rats as the activating systems. Mutations at the sodium/potassium ATPase and hypoxanthine:guanine phosphoribosyltransferase loci were measured by resistance to ouabain and 6-thioguanine (TG). The order of effectiveness in generating mutagens from BOP was hamster duct, hamster acinar, rat duct, rat acinar. These data show extensive differences in BOP activation by hamster acinar and duct tissue.

Animals↗