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Biomedical subjects

M Lehmann

Publications and source records attributed to M Lehmann.

At least 199 records · Page 11Linked to original sources
PubMed1993

Neural cell adhesion molecule and prognosis of surgically resected lung cancer.

The prognostic significance of the expression of neural cell adhesion molecule (NCAM), a neuroendocrine antigen in lung cancer, was analyzed by an indirect immunoperoxidase method in 97 surgically treated patients. Reactivity of MOC-1 and S-L 11.14, both cluster-1 monoclonal antibodies directed against NCAM, was positive in all nine small-cell lung cancers and in 16 of 88 (18%) non-small-cell lung cancers. For the latter group, this expression demonstrated a phenotypic heterogeneity that was mainly observed in poorly differentiated squamous cell carcinomas and in stage N2 non-small-cell lung cancers. Patients with NCAM-positive non-small-cell lung cancer proved to have a shorter survival than those with NCAM-negative disease. In Cox's model for multivariate analysis, nodal status and histology were the main independent determinants of prognosis. We therefore concluded that NCAM expression in non-small-cell lung cancer is correlated to nodal status and that it indicates a poor prognosis. These findings confirm that the diversification of lung cancer phenotype leads to tumor progression and brings a negative prognosis to surgically resected non-small-cell lung cancer. However, nodal status remains the most important prognostic variable, suggesting that NCAM expression is only one of numerous biological events that promote tumor progression.

Adenocarcinoma↗
PubMed1993

Overtraining in endurance athletes: a brief review.

Overtraining is an imbalance between training and recovery, exercise and exercise capacity, stress and stress tolerance. Stress is the sum of training and nontraining stress factors. Peripheral (short-term overtraining, STO) or peripheral and central fatigue may result (long-term overtraining, LTO). STO lasting a few days up to 2 wk is termed overreaching. STO is associated with fatigue, reduction, or stagnation of the 4 LT performance capacity (performance at 4 mmol lactate or comparable criterion), reduction of maximum performance capacity, and brief competitive incompetence. Recovery is achieved within days, so the prognosis is favorable. LTO lasting weeks or months causes overtraining syndrome or staleness. The symptomatology associated with overtraining syndrome has changed over the last 50 yr from excitation and restlessness (so-called sympathetic form) to phlegmatic behavior and inhibition (so-called parasympathetic form). Increased volume of training at a high-intensity level is likely the culprit. The parasympathetic form of overtraining syndrome dominates in endurance sports. Accumulation of exercise and nonexercise fatigue, stagnation, or reduction of the 4 LT performance capacity, reduction in maximum performance capacity, mood state disturbances, muscle soreness/stiffness, and long-term competitive incompetence can be expected. Complete recovery requires weeks and months, so the prognosis is unfavorable. Other optional or further confirmation requiring findings include changes in blood chemistry variables, hormone levels, and nocturnal urinary catecholamine excretion. Based on the findings reported, recommendations for training monitoring can be made, but their relevance in the practice must still be clarified.

Exercise↗
PubMed1992

Suppressing effect of vanillin on chromosome aberrations that occur spontaneously or are induced by mitomycin C in the germ cell line of Drosophila melanogaster.

In order to investigate the anticlastogenic effect of vanillin on ring-X loss, D. melanogaster females exposed to different vanillin concentrations were crossed with non-treated, MMC- or MMS-treated males. The results obtained with this in vivo investigation showed a significant inhibition of vanillin in the frequencies of spontaneous ring-X loss--59, 56, 38 and 36%--at the different concentrations used. In addition, vanillin treatment caused a significant suppression of MMC-induced ring-X loss. This decrease was observed only in the first 3 days after the interruption of vanillin treatment and at the concentrations of 0.5 and 1% of this flavoring agent. In contrast, vanillin did not show any effect on chromosome loss provoked by MMS. Therefore, the ring-X loss-decreasing effect of vanillin seemed to depend on the quality of DNA lesions and consequently on a specific enzymatic repair process present in the oocytes of D. melanogaster.

Animals↗
PubMed1992

Training-overtraining: influence of a defined increase in training volume vs training intensity on performance, catecholamines and some metabolic parameters in experienced middle- and long-distance runners.

The influence of an increase in training volume (ITV; February 1989) vs intensity (ITI; February 1990) on performance, catecholamines, energy metabolism and serum lipids was examined in two studies on eight, and nine experienced middle- or long-distance runners; seven participated in both studies. During ITV, mean training volume was doubled from 85.9 km.week-1 (pretrial phase) to 174.6 km within 3 weeks. Some 96%-98% of the training was performed at 67 (SD 8)% of maximal performance. During ITI, speed-endurance, high-speed and interval runs increased within 3 weeks from 9 km.week-1 (pretrial phase) to 22.7 km.week-1 and the total training distance from 61.6 to 84.7 km.week-1. The ITV resulted in stagnation of running velocity at 4 mmol lactate concentration and a decrease in total running distance in the increment test. Heart rate, energy metabolic parameters, nocturnal urinary catecholamine excretion, low density, very low density lipoprotein-cholesterol and triglyceride concentrations decreased significantly; the exercise-related catecholamine plasma concentrations increased at an identical exercise intensity. The ITI produced an improvement in running velocity at 4 mmol lactate concentration and in total running distance in the increment test; heart rate, energy metabolic parameters, nocturnal catecholamine excretion, and serum lipids remained nearly constant, and the exercise-related plasma catecholamine concentrations decreased at an identical exercise intensity. The ITV-related changes in metabolism and catecholamines may have indicated an exhaustion syndrome in the majority of the athletes examined but this hypothesis has to be proven by future experimental studies.

Adult↗
PubMed1992

Decreased nocturnal catecholamine excretion: parameter for an overtraining syndrome in athletes?

The effectiveness of high performance training should be examined at short intervals in order to recognize overtraining promptly. Field or laboratory tests can usually not be performed with such frequency. Easy-to-measure biological, training-relevant parameters are being sought to use in their place. Since the importance of the sympathetic nervous system for adaptation of stress and the relationship between physical training and the activity of the sympathetic nervous system are well accepted, and since an impairment of the sympathetic nervous system is assumed in an overtraining syndrome, we examined the relevance of nocturnal "basal" urinary excretion of free catecholamines with respect to its practical application: 1. during a pilot study (training of road and track cyclists before the 1988 Olympic Games in Seoul), 2. through a 4-week prospective, experimental study in 1989 and 1990 (middle- and long-distance runners), 3. during the competitive season and winter break of a soccer team between August 1990 and April 1991. The following hypothesis was made: An overtraining or exhaustion syndrome in athletes may usually be accompanied by at least a 50% decrease in basal dopamine, noradrenaline and adrenaline excretion. When training is effective or the athletes are not exhausted, the decrease of the excretion rate--with the exception of dopamine--is more likely to be lower (noradrenaline, adrenaline). Generalization of these results requires further expansion of the experimental basis.

Adult↗
PubMed1992

Induction of long-term survival of rat skin allografts by a novel, highly efficient anti-CD4 monoclonal antibody.

The new monoclonal antirat CD4 antibody RIB 5/2, which detects another epitope than those covered by W3/25 and MRC OX35, was tested for its immunosuppressive potency following skin allografting by using strain combinations with different genetic barriers in the MHC and genetic low- or high-responder background. High-dose and long-term therapy of the grafted rats led to a significant delay of the acute rejection (P < 0.01) in the strain combination Wistar Furth-to-BDX as well as in LEW1W-to-LEW1A. No significant prolongation of the mean allograft survival time was obtained for the high-responder rats (LEW1A-to-LEW1W). Cytofluorometric analysis revealed that RIB 5/2 exerts the immunosuppressive activity predominantly by modulation of the CD4 glycoprotein. Furthermore, the dependence of the humoral immune response against the mouse-globulins upon the administered protein quantity could be demonstrated.

Animals↗
PubMed1992

[Detection of lectin binding sites in the trophoblast of cattle during early pregnancy].

In the present study we report on the histotopographical distribution of lectin binding sites in the trophoblasts of day 18 to day 40 bovine embryos, using the FITC-labeled lectins BPA, Con A, DBA, GS I, GS II, MPA, PNA, SBA, UEA I and WGA. Lectin binding sites localized in giant binucleate cells differ from those localized in uninucleate cells, indicating changes in the biochemical structure of cell surfaces taking place during differentiation. In the trophoblast of the day 40 embryo, a distinct staining of uninucleate cells was seen after incubation with GS I, Con A and MPA, demonstrating N-acetylgalactosamine (GS I), Mannose (Con A) and Galactose (MPA) moieties, whereas giant binucleate cells showed intense reactions after incubation with DBA and WGA, indicating presence of N-acetylgalactosamine (DBA) and N-acetylglucosamine (WGA). GS II (specific for N-acetylglucosamine), SBA (specific for N-acetylgalactosamine) and UEA I (specific for L-Fucose) showed no affinity toward any of the examined tissues. We assume, that carbohydrate moieties in trophoblast cells play an important role in fetomaternal cell-cell adhesion and cell migration during implantation and placentation period.

Animals↗
PubMed1992

[The development of the yolk sac in ruminants (sheep and cattle)].

Yolk sac development was investigated in 69 ovine and 10 bovine embryos from the blastocyst stage to the 7th week of gestation. Light and electron microscopical findings are reported. The yolk sac in sheep and cattle is composed of an enlarged sac-like portion lying below the embryo and two ends which follow the elongated course of the trophoblast. In sheep, an open connection exists between the intestines and the yolk sac up to a crown-rump length (CRL) of 9 mm. It is closed by 12 mm CRL. The wall of the yolk sac is especially well vascularized in the enlarged, sac-like portion. Primary erythropoiesis occurs within the blood capillaries. In the blastocyst, the yolk sac entoderm is made up of elongated, flat cells. It becomes cuboidal in the 3 mm embryo (ovine) and later columnar. The up to 20 microns tall cells stain darkly and contain numerous light-colored vesicles. At 4.5 mm CRL light cells appear between the dark ones. Both cells are rich in rough endoplasmic reticulum (rER). The increased staining of the darker cells is due to an osmophilic cytoplasm and numerous, often parallel lamella of rER. The rER of the light cells is enlarged to irregularly-shaped cisternae, which nearly fill the entire cytoplasm and give them a rounded appearance. The dark cells contain polygonal nuclei, whereas those in the light cells are round with one or two nucleoli. The oval mitochondria have only a few peripheral cristae. Golgi fields are not very common. Cells of the entoderm are connected to one another over zonulae occludentes. They possess microvilli on the luminal surface and are supported by a basement membrane. From 5 mm CRL onwards (ovine), the yolk sac entoderm folds itself between the capillaries, thereby becoming stratified. The intercellular space between the cells expands as projections between neighboring cells interlock. Canaliculi arise between adjacent epithelia. The wall of the yolk sac thickens as a result of this infolding and the densely packed capillaries. Infoldings are especially predominant in the sac-like portion of the yolk sac, and only suggested in the ends. Involution of the yolk sac begins in the peripheral end segments and proceeds centripetally. Numerous glycogen particles appear in the yolk sac entoderm cells of the ovine fetus at a CRL of 36 mm, and by a CRL of 42 mm, the sac-like portion has also begun to show signs of degeneration. Mesenchyme is very sparse within the wall of the yolk sac throughout the entire period of development.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Training-overtraining: performance, and hormone levels, after a defined increase in training volume versus intensity in experienced middle- and long-distance runners.

Performance and hormones were determined in eight middle- and nine long-distance runners after an increase in training volume (ITV, February 1989) or intensity (ITI, February 1990). Seven runners participated in both studies. The objective was to cause an overtraining syndrome. The mean training volume of 85.9 km week-1 increased within 3 weeks to 176.6 km week-1 during ITV and 96-98% of training volume was performed as long-distance runs at mean(s.d.) 67(8)% of maximum capacity. Speed endurance, high-speed and interval runs averaging 9 km week-1 increased within 3 weeks to 22.7 km during ITI, and the total volume increased from 61.6 to 84.7 km. A plateau in endurance performance and decrease in maximum performance occurred during ITV, probably due to overtraining, with performance incompetence over months. Nocturnal catecholamine excretion decreased markedly (47-53%), contrary to exercise-related plasma catecholamine responses, which increased. Resting and exercise-related cortisol and aldosterone levels decreased. Improvement in endurance and maximum performance occurred during ITI indicating a failure to cause an overtraining syndrome in ITI. Decrease in noctural catecholamine excretion was clearly lower (9-26%), exercise-related catecholamine responses showed a significant decrease, cortisol and aldosterone levels remained almost constant, exercise-related prolactin levels decreased slightly. There were no differences in insulin, C-peptide, free testosterone, somatotropic hormone (STH), follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), tri-iodothyronine (T3) and thyroxine (T4). The decrease in nocturnal catecholamine excretion during ITV might indicate a decrease in intrinsic sympathetic activity in exhausted sportsmen. But it remains open whether this reflected a central nervous system incompetence.

Adult↗
PubMed1992

[Secretion of hCG by mononuclear cells--a specific and essential reaction in pregnancy?].

Mononuclear cells in peripheral blood secrete immunoreactive hCG (ir-hCG) when they are stimulated in in-vitro culture with the proteinkinase C - activator phorbol-myristat-acetate (TPA). We examined the ir-hCG secretion in 61 fertile and 191 pregnant women and 38 men. Mononuclear cells of pregnant women secrete after TPA stimulation significantly more ir-hCG than mononuclear cells on non-pregnant but fertile women. This effect can be detected as early as 23rd days of a menstrual cycle which is accompanied by conception and persisted over the entire duration of a pregnancy. Maximal effects were observed in the 7th to 19th and 30th to 34th weeks of pregnancy. An artefact caused by adhesive serum-hCG could be excluded. The elevated potential of the mononuclear cells to be stimulated remained intact for about 14 days after termination of a normal pregnancy in the first trimester. An ir-hCG secretion similar to that seen in nonpregnant women was found in patients with early abortion. The possible physiological importance of the in-vivo secretion of beta-HCG during pregnancy is discussed.

Abortion, Incomplete↗
PubMed1992

[Interval resistance exercise in comparison with bicycle ergometry stress. Studies with resistance endurance training in coronary patients].

UNLABELLED: In the rehabilitation of coronary patients there is an increased interest in using complementary resistance exercise training. Therefore, we studied nine patients (males; age: 51 +/- 7 years) with chronic stable coronary heart disease during extensive resistance exercise (ex RE) (legpress, abduction, adduction) (60-s work: 60-s rest; contraction intensity: 65% of 1 RM) and during intensive resistance exercise (int. RE) (legpress) (30-s work: 45-s rest) with 85% of 1 RM. Non-invasive continuously measured blood pressure, heart rate, norepinephrine, epinephrine, lactic acid, and glucose were compared with values from maximal bicycle ergometry (3-min steps, each 25 w; max. performance: mean 156 w; range 125-200 w). RESULTS: 1) Comparing ex RE and int RE with bicycle ergometry there were no differences in blood pressure (systolic: 206 and 204 vs. 210 mm Hg; ns; diastolic: 98 and 104 vs. 92 mm Hg; ns). Heart rates (104 and 103 vs. 125/min; p < .01), norepinephrine (3.8 and 3.3 vs. 8.8 nmol/l; p < .01) and epinephrine (0.7 and 0.6 vs. 1.4 nmol/l; p < .01) were considerably lower. 2) The most significant increase and decrease of blood pressure and heart rate occurred within 15-30 s after the beginning and end, respectively, of isometric exercise. CONCLUSIONS: 1) ex RE is suitable for patients with stable CHD and cardiac exercise tolerances of 1.5-2 W/kg = 125-150 watts. 2) Blood pressure monitoring by the cuff method (RR) immediately after RE did not reflect blood pressure during RE. 3) Controlling RE by the training heart rate prescribed for endurance exercise is not possible.

Adult↗
PubMed1991

Sympathetic autonomic dysfunction. Programmed subcutaneous noradrenaline administration via microdosing pump.

Sympathetic dysfunction is characterized by postural hypotension, decreasing blood pressure without compensatory tachycardia during graded supine ergometric exercise, impaired catecholamine metabolism, and hypersensitivity to catecholamines. We report on eight patients, seven with sympathetic dysfunction, of whom three patients were treated for the first time with programmed subcutaneous noradrenaline administration by means of a microdosing pump over a time period of 1.5-13 months. A clear improvement in blood pressure values, orthostasis tolerance, and exercise capacity has been observed in these three patients which permit them to extend their action radius. Adjustment of the noradrenaline dose to the wide range of everyday stress and the possible occurrence of adrenoreceptor desensitization, however, remains a severe problem.

Adult↗
PubMed1991

Structural analysis of the actinophage phi C31 attachment site.

The lysogenisation of actinophage phi C31 in S. coelicolor J 1501 occurs by site-specific recombination. The DNA segments containing the attachment sites on the host chromosome, the phage genome and the two junctions created by the insertion of the prophage were cloned and the nucleotide sequences determined. The attachment sites (att) share an extremely short common sequence of three base pairs. Adjacent to the core sequences some direct- and inverted repeats were found as potential binding sites for proteins involved in site-specific recombination.

Attachment Sites, Microbiological↗
PubMed1991

Combination of culture on collagen gels and glucose starvation for cloning human colon cancer cells. Obtention of clones exhibiting different patterns of enterocytic differentiation.

Glucose starvation has been widely used to select differentiated subpopulations from the heterogenous human colon cancer cell line HT29. We observed that the important cell loss elicited by culturing these cells in glucose-free medium could be limited when type I collagen gel was used as substratum instead of conventional plastic support. We took advantage of this property to develop a new protocol, which combined glucose starvation and culture on collagen gels, for cloning HT29 cells. Using this procedure we have isolated four clones that were characterized on the basis of morphological (optical and transmission electron microscopy), electrophysiological (determination of transepithelial electrical parameters) and biochemical (detection of villin, sucrase-isomaltase and carcinoembryonic antigen) criteria. These four clones expressed different patterns of enterocytic differentiation regarding to these criteria. These results confirmed the heterogeneity of the HT29 cell line. One of these clones, HT29-A7, which displayed numerous intercellular cysts that disappeared at confluency, appears as a complementary model in the study of epithelial biogenesis.

Cell Differentiation↗
PubMed1991

Training-overtraining. A prospective, experimental study with experienced middle- and long-distance runners.

Overtraining may be one frequent cause of stagnation or decrease in performance capacity of athletes. Israel (19) differentiates between addisonoid (parasympathetic) and basedowoid (sympathetic) overtraining, characterized by inhibition or excitation. We tried to induce an overtraining syndrome in 8 experienced middle- and long-distance runners, based on an increase in training volume from an average 85.9 km (week 1) to 115.1 km (week 2) and 143.1 km (week 3) to 174.6 km per week (week 4). The influence of this training on cardiovascular, metabolic and hormonal parameters was examined with special respect to plasma and urinary catecholamines. Laboratory testing including graded treadmill running was performed on the days 0, 14 and 28. Training was held six days each week, with nearly 30 km per day in the fourth week. A stagnation in endurance performance capacity (running velocity at the aerobic-anaerobic transition range) and a decrease in maximum working capacity were observed in 6 and a stagnation in 2 of the 8 sportsmen, indicated by a decrease in total running distance from 4719 + 912 m to 4361 + 788 m during incremental treadmill ergometry. The sportsmen could neither improve nor could they even approximately reach their personal records during the subsequent competitive season. Subjective complaints, classified on a four-point scale, increased from 1.2 (week 1) to 3.2 in week 4. Glucose, lactate, ammonia, glycerol, free fatty acids, albumin, LDL, VLDL cholesterol, hemoglobin level (transient), leukocytes, and heart rate (before and during exercise) decreased significantly. Urea, creatinine, uric acid, GOT, GPT, gamma-GT, serum electrolytes (except phosphate and calcium) remained constant at the measuring times, CPK was elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗