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Biomedical subjects

H Northoff

Publications and source records attributed to H Northoff.

At least 37 records · Page 2Linked to original sources
PubMed2001

Semifluorinated symmetrical diethers for intraocular use: synthesis, characterization, and in vitro biocompatibility.

Semifluorinated symmetrical diethers were synthesized using the William ether synthesis. These diethers should have similar properties to perfluorocarbons as are chemical inertness and high oxygen solubility, but in contrast a considerably lower density. With their lower density the damaging of the choroidal tissue of the eye observed with perfluorocarbons should be avoided. The synthesized diethers are inert compounds being stable against nucleophiles, oxidiziers and strong bases. Their density is in the range of 1.1-1.2 g/cm3. Besides the physical and chemical tests we conducted several in vitro biocompatibility tests. The tests comprised induction of hemolysis, the generation of C3a complement, the influence on the production of interleukin1beta, the influence on cell proliferation of a Raji and a Hela cell line (3H-Thymidine uptake) and finally the direct cytotoxic effect on these cell lines. All tested symmetrical diethers were positive in one or more tests and can be expected to be incompatible in vivo. Especially the "short" semifluorinated diethers [(CF3CH2O)2(CH2)3-6] showed a nearly total inhibition of cell proliferation or interleukin1beta release. Further variation of the compounds will be necessary to generate better biocompatible derivates.

Cell Division↗
PubMed2001

In vitro secretion kinetics of proteins from Legionella pneumophila in comparison to proteins from non-pneumophila species.

It has been shown that the loss of PilD, a prepilin peptidase necessary for type IV pilus biogenesis and establishment of the type II secretion apparatus is associated with loss of virulence in Legionella pneumophila. L. pneumophila is the species most frequently associated with Legionnaires' disease, but virulence factors unique to this species are not known, so the secretion kinetics of several pilD-dependent enzyme activities, including protease, acid phosphatase, phospholipase A (PLA) and lysophospholipase A (LPLA), of L. pneumophila and non-pneumophila species were compared during growth in BYE broth. Enzyme activity appeared during mid-exponential growth phase and reached maximal levels on entry into stationary growth phase. None of the enzyme activities were unique to L. pneumophila and it did not exclusively secrete the highest amounts of the hydrolytic proteins. However, the timing of PLA and LPLA secretion in L. pneumophila differed compared to other species. PLA activity was secreted prior to LPLA activity in L. pneumophila, which may lead to an accumulation of the cytotoxic agent lysophosphatidylcholine (LPC). In addition to L. pneumophila, several other Legionella species, including Legionella steigerwaltii and Legionella gormanii, were able to enrich for LPC due to a very potent PLA activity accompanied by only moderate LPLA activity. These species, in contrast to L. pneumophila, have not been shown to multiply within monocytic host cells. Thus none of the secreted enzymic activities investigated were unique to L. pneumophila, nor were they secreted at high concentrations. However, the timing of PLA and LPLA secretion may contribute to pathogenicity.

Acid Phosphatase↗
PubMed2001

Changes of HSP72-expression in leukocytes are associated with adaptation to exercise under conditions of high environmental temperature.

Overexpression of the heat shock protein HSP72 provides thermotolerance. We asked if two consecutive endurance runs 1 week apart (CR1, CR2) and additional environmental heat stress affect HSP72-expression in leukocytes of nonheat-acclimated endurance athletes. Twelve subjects were allocated randomly into two groups. Group HH completed both runs at 28 degrees C ambient temperature, and group NH performed CR1 at 18 degrees C and CR2 at 28 degrees C. HSP72-expression was determined by flow cytometry and RT-PCR before and 0, 24, and 48 h after exercise. Additionally, post-exercise cells were exposed to in vitro heat shock (HS; 2 h, 42 degrees C). The prolonged, high HSP72 protein level after CR1 in HH compared with NH may reflect thermotolerance induced by endurance exercise at high ambient temperature. Adaptation of cardiocirculatory/thermoregulatory capacity after CR2 in HH went along with a more rapid down-regulation of HSP72 compared with CR1. HSP72 mRNA demonstrated temperature-related changes after exercise. The reduced HS response in vitro after CR2 may represent exercise-related adaptation mechanisms. HSP72 concentrations in leukocytes may indicate previous exercise- and temperature-related stress conditions and adaptation in immunocompetent cells.

Adaptation, Physiological↗
PubMed2001

Free radicals, exercise, apoptosis, and heat shock proteins.

Free radicals are an integral part of metabolism and are formed continuously in the body. Many sources of stress heat, irradiation, hyperoxia, inflammation and any increases in metabolism including exercise, injury, and even repair processes lead to increased production of free radicals and associated reactive oxygen or nitrogen species (ROS/RNS). Evidence is accumulating that free radicals have important functions in the signal network of cells, including induction of growth and apoptosis and as killing tools of immunocompetent cells. Endogenous and nutritional antioxidant systems have to be adjusted to ensure adequate removal of radicals during stress to prevent damage to membranes, proteins, or nucleic acids. Excessive stress will induce DNA damage in the form of oxidized nucleosides, strand breaks, or DNA-protein crosslinks. Possible consequences of DNA damage are repair, apoptosis/necrosis, or defective repair leading to DNA sequence alterations and possibly to the development of cancer or, in case of mitochondrial DNA, to metabolic dysfunction. Excessive exercise will also induce DNA damage in peripheral leukocytes. The good message is that moderate stress in form of regular exercise/training may have protective effects against exercise-induced DNA damage. Up-regulation of endogenous antioxidant defense systems and complex regulation of repair systems such as heat shock proteins (HSP 70, HSP 27, HO 1) are seen in response to training and exercise. Up-regulation of antioxidants and modulation of the repair response may be mechanisms by which exercise can beneficially influence our health. Massive intervention into the redox state by pharmaceutical doses of exogenous antioxidants should be regarded with caution due to the ambiguous role of free radicals in regulation of growth, apoptosis, and cytotoxicity by immunocompetent cells.

Adaptation, Biological↗
PubMed2000

Localization of Legionella bacteria within ribosome-studded phagosomes is not restricted to Legionella pneumophila.

In this report, we investigate the intracellular fate of selected members of the genus Legionella within the monocytic cell line Mono Mac 6 cells. By means of electron microscopy and immunocytochemistry, we could show that Legionella pneumophila as well as Legionella longbeachae are able to induce ribosome-studded phagosomes which associate with the rough endoplasmic reticulum (RER), whereas Legionella micdadei remains to be located within smooth phagosomes but also shows signs of RER association. In addition, we could demonstrate a remarkable correlation between the phagosome type and the morphological phenotype of intracellular bacteria: within ribosome-studded phagosomes, bacteria generally lacked the outer coat of low electron density whereas bacteria within the smooth phagosomes still possessed this outer coat. The virulence factors responsible for inhibition of phagosome maturation and their distribution within the genus Legionella as well as the biological significance of the morphological difference of bacteria within smooth and ER-associated phagosomes remain to be investigated.

Endoplasmic Reticulum↗
PubMed2000

Change in perforin-positive peripheral blood lymphocyte (PBL) subpopulations following exercise.

Perforin, one of the cytotoxic proteins of the immune system, plays a prominent role in protection against viral and bacterial infections. We investigated its expression in PBL and their CD3+, CD4+, CD8+ and CD16+ and/or CD56+ subpopulations in endurance athletes before and after a triathlon. Lymphocyte subpopulations were analysed by flow cytometry following separation of peripheral blood mononuclear cells and staining with antibodies against specific membrane antigens and intracellular perforin. The number of total lymphocytes decreased from 2.1 x 10(3)/microl before the triathlon to 1.0 x 10(3)/microl 1 h after the triathlon (P < 0.01). Interestingly, there was already a significant spontaneous decline in the percentage of CD3+/perforin+, and in CD8+/perforin+ cells, in the week proceeding the triathlon, when subjects were instructed to refrain from strenuous exercise training. The percentage of CD3+/perforin+, CD8+/perforin+ and CD16+ and/or CD56+/perforin+ cells in each lymphocyte subpopulation decreased 1 h after exercise even further from 14.3% to 5.8% (P < 0.05), 18.5% to 6.5% (P < 0.05) and 77.3% to 67.3%, respectively. However, at 18 h and 48 h after exercise the percentage of perforin-expressing CD3+, CD8+ and CD16+/56+ cells increased again towards baseline levels. Compared with normal controls, baseline perforin co-expression in CD3+ and CD8+ lymphocytes was significantly higher in trained athletes. From our data we conclude that trained athletes have an increased percentage of perforin+ PBL and that following exercise the percentage of perforin+ and therefore potentially cytotoxic lymphocytes transiently decreases in peripheral blood.

Adult↗
PubMed2000

Physical exercise-induced expression of inducible nitric oxide synthase and heme oxygenase-1 in human leukocytes: effects of RRR-alpha-tocopherol supplementation.

This study evaluated the effects of RRR-alpha-tocopherol (500 IU/day, 8 days) on in vivo cytokine response and cytoplasmic expression of inducible nitric oxide synthase (iNOS) and the antioxidant stress protein heme oxygenase-1 (HO-1) in human leukocytes after exhaustive exercise. Thirteen men were investigated in a double-blind, placebo-controlled, cross-over study with a wash-out period of 28 days. The exercise procedure consisted of an incremental treadmill test followed by a continuous run until exhaustion at 110% of the individual anaerobic threshold (total duration 28.5 +/- 0.8 min). HO-1 and iNOS protein were assessed in mono- (M), lympho-, and granulocytes (G) using flow cytometry. Plasma interleukin-6 (IL-6) and IL-8 were measured by ELISA. IL-6 rose significantly whereas IL-8 did not exhibit significant changes after exercise. Changes of IL-6 were not affected by RRR-alpha-tocopherol. Exercise induced an increase of iNOS protein primarily in M and G. A small, but significant, increase of HO-1 protein was measured in M and G. RRR-alpha-Tocopherol did not show any significant effects on cytoplasmic expression of iNOS and HO-1 at rest and after exercise. In conclusion, exhaustive exercise induces expression of iNOS and HO-1 in human leukocytes by a mechanism that is not sensitive to RRR-alpha-tocopherol supplementation.

Adult↗
PubMed2000

HSP expression in human leukocytes is modulated by endurance exercise.

PURPOSE: Temperature increase, oxidative stress, and inflammatory reactions after endurance exercise were expected to stimulate the synthesis of heat shock proteins (HSP) in peripheral blood leukocytes. Furthermore, it was of interest whether regular endurance training influences HSP expression. METHODS: The expression of HSP27, HSP60, HSP70, constitutive HSC70, and HSP90 in the cytoplasma and surface of lymphocytes, monocytes, and granulocytes of 12 trained athletes was analyzed by flow cytometry before and after (0, 3, and 24 h) a half marathon. Twelve untrained persons at rest were included as control. RESULTS: After the race, there was a significantly greater percentage of leukocytes expressing cytoplasmic HSP27, HSP60, and HSP70 (P < 0.01), whereas HSC70 and HSP90 remained unchanged. The fluorescence intensity increased significantly in monocytes for HSP27 (0 and 3 h) and HSP70 (0, 3, and 24 h) and in granulocytes, only 24 h postexercise for HSP70. The percent values of trained athletes at rest were significantly lower compared with untrained persons (P < 0,01). CONCLUSIONS: Strenuous exercise increased HSP expression in blood immediately after the run, indicating a protective function of HSP in leukocytes of athletes to maintain function after heavy exercise. The downregulation of HSP-positive cells in trained athletes at rest seems to be a result of adaptation mechanisms to regular endurance training.

Adaptation, Physiological↗
PubMed2000

Expression of the inducible nitric oxide synthase (iNOS) in human leukocytes: responses to running exercise.

INTRODUCTION: We examined the influence of two different bouts of vigorous running exercise on the expression of the inducible nitric oxide synthase (iNOS) in leukocytes (LE). METHODS: In study 1, 10 trained runners competed in a half marathon (HM) lasting 90.5 +/- 11.0 min. In study 2, 8 untrained subjects performed a graded treadmill test followed by a continuous run (CR) until exhaustion (11.3 +/- 1.3 min). iNOS mRNA levels were assessed by RT/PCR at rest, 0, 3, and 24 h after HM and CR. In study 2, iNOS was additionally analyzed at the protein level in lympho- (L), mono- (M), and granulocytes (G) by flow cytometry at rest and up to 48 h after CR. RESULTS: Analysis revealed a rise of the iNOS transcript directly after the HM in 8 of 10 subjects. In study 2, the expression of iNOS protein at rest differed between L (mean +/- SE: 30.9 +/- 4.5% iNOS positive cells), M (91.3 +/- 4.0%), and G (64.9 +/- 10.3%): 3 h after CR, expression of iNOS increased in L (67.3 +/- 7.4%) and G (90.3 +/- 2.9%) and was still elevated 48 h post-exercise. However, our measurements failed to detect significant changes of leukocyte iNOS mRNA in response to CR. After the HM, our findings were paralleled by elevated plasma levels of interleukin-8, myeloperoxidase (MPO), and partly of TNF-alpha, whereas CR only induced a low rise of MPO. CONCLUSION: Our investigations revealed an increased expression of iNOS at the transcriptional and translational level in response to vigorous exercise. This reflects an inflammatory response and may contribute to an exercise-induced rise of endogenous nitric oxide production. It remains unclear if these effects serve an in-vivo immunoregulatory or cell-damaging role.

Adult↗
PubMed2000

Influence of Acanthamoeba castellanii on intracellular growth of different Legionella species in human monocytes.

Previous studies using a murine model of coinhalation of Legionella pneumophila and Hartmannella vermiformis have shown a significantly enhanced intrapulmonary growth of L. pneumophila in comparison to inhalation of legionellae alone (J. Brieland, M. McClain, L. Heath, C. Chrisp, G. Huffnagle, M. LeGendre, M. Hurley, J. Fantone, and C. Engleberg, Infect. Immun. 64:2449-2456, 1996). In this study, we introduce an in vitro coculture model of legionellae, Mono Mac 6 cells (MM6) and Acanthamoeba castellanii, using a cell culture chamber system which separates both cell types by a microporous polycarbonate membrane impervious to bacteria, amoebae, and human cells. Whereas L. pneumophila has shown a maximal 4-log-unit multiplication within MM6, which could not be further increased by coculture with Acanthamoeba castellanii, significantly enhanced replication of L. gormanii, L. micdadei, L. steigerwaltii, L. longbeachae, and L. dumoffii was seen after coculture with amoebae. This effect was seen only with uninfected amoebae, not with Legionella-infected amoebae. The supporting effect for intracellular multiplication in MM6 could be reproduced in part by addition of a cell-free coculture supernatant obtained from a coincubation experiment with uninfected A. castellanii and Legionella-infected MM6, suggesting that amoeba-derived effector molecules are involved in this phenomenon. This coculture model allows investigations of molecular and biochemical mechanisms which are responsible for the enhancement of intracellular multiplication of legionellae in monocytic cells after interaction with amoebae.

Acanthamoeba↗
PubMed2000

Transcriptional and translational regulation of heat shock proteins in leukocytes of endurance runners.

Heat shock proteins (HSP) represent cell-protective and antioxidant systems that may be induced by reactive oxygen species, cytokines, and hyperthermia. In the present study, we evaluated the influence of heavy endurance exercise and training on HSP27 and HSP70 in peripheral leukocytes of 12 athletes (before and at 0, 3, and 24 h after a half-marathon) and 12 untrained controls on protein and mRNA levels by flow cytometry and RT/PCR, respectively. HSP transcripts increased significantly immediately after acute exertion accompanied by elevated levels of corresponding proteins. HSP protein expression remained high until 24 h postexercise. Significant increases of plasma interleukin-8, myeloperoxidase, and creatine kinase occurred after exercise. Basal HSP expression was usually lower in trained compared with untrained subjects. Applying in vitro heat shock to resting blood samples of all subjects significantly stimulated HSP mRNA, showing higher increases in trained individuals. The exercise-induced alterations indicate that immunocompetent cells became activated. In addition to heat stress, other exercise-associated stress agents (oxidants, cytokines) may have also participated in stimulation of HSP expression in leukocytes. The expression pattern of HSP due to training status may be attributed to adaptive mechanisms.

Actins↗
PubMed2000

Upper respiratory tract infection in athletes: influence of lifestyle, type of sport, training effort, and immunostimulant intake.

Epidemiological evidence suggests that heavy acute or chronic exercise is related to an increased incidence of upper respiratory tract infections in athletes, while moderate exercise is believed to be protective. During the past years, many groups have investigated the association between changes within the immune system and exercise at different intensity levels. Although following strenuous exercise, some immunologic alterations were quite consistent and reproducible, e.g. neutrophilia, lymphopenia, and depression of natural killer cell activity, some findings were divergent or strongly dependent on the study design and athletes investigated. Lately, interesting results in the field of psychoneuroimmunolgy as well as new insights in the relationship between macro- and micronutrient and the immune system have brought up new fields of research interest. There is growing evidence that e.g. lifestyle factors, the coping with daily stress, and dietary behavior are important cofactors in the immune response to exercise. The present work gives a short review on the literature dealing with URTI in athletes with special reference to the above mentioned cofactors. In addition, the results of a recent investigation concerning training and associated lifestyle patterns in German athletes are presented.

Adjuvants, Immunologic↗
PubMed1999

[Effect of lymphocyte-conditioned medium on expression of smooth muscle alpha-actin in lens epithelium cells in situ].

PURPOSE: Contraction of the capsule of the ocular lens is based upon proliferation and contraction of transformed lens epithelial cells. It is assumed that these processes can be assisted by postoperative intraocular inflammation. Previously, we reported that lens epithelial cell proliferation is enhanced by lymphocyte-conditioned medium (LCM). In this study we investigated the effect of LCM as well as of a culture medium conditioned by pigmented ciliary epitheilal cells (CBCM) on the expression of the smooth-muscle alpha-actin of the contractile cytoskeletal elements. METHODS: Explants of the anterior lens capsule of freshly enucleated bovine eyes were cultured in serum-free LCM and CBCM for 3 days, followed by fixation. Smooth-muscle alpha-actin was identified by indirect immunoflorescence. Explants cultured in serum-free bFGF-containing and TGF-beta containing medium served as control. RESULTS: Lens epithelial cells expressed smooth-muscle alpha-actin under the influence of LCM or TGF-beta. No smooth muscle alpha-actin could be detected under the influence of CBCM or bFGF. CONCLUSION: Our results demonstrate that secreted molecules of activated lymphocytes are able to induce the transformation of lens epithelial cells into contractile myofibroblasts and may be involved in the post-operative contraction of lens capsules.

Actins↗
PubMed1999

Expression of the antioxidant stress protein heme oxygenase-1 (HO-1) in human leukocytes.

Inducible heme oxygenase (HO-1) is an antioxidant stress protein, that is mainly induced by reactive oxygen species (ROS), cytokines and hyperthermia. By using flow cytometry the present investigation demonstrated a rise in the cytoplasmic expression of HO-1 in lympho- (L), mono- (M) and granulocytes (G) of 9 endurance-trained male subjects after a half marathon run. The expression was more pronounced in M (median: 98.3% HO-1 positive cells/4.31 mfc) and G (94.8%/1.93 mfc) than in L (80.1%/1.51 mfc) when measured 3 h post-exercise. Additionally the exercise protocol caused a rise in the plasma levels of myeloperoxidase, TNF alpha and interleukin-8 (IL-8), indicating an inflammatory response. We could detect a correlation between IL-8 and HO-1, directly after exercise, that was apparent in G (r = 0.67, p < .05) and L (r = 0.80, p < .05), but did not reach significance in M (r = 0.65, p = 0.06). An additional detection of HO-1 at rest in 12 untrained subjects showed a higher baseline expression of HO-1 compared to the athletes. The regulatory pathways leading to an increased expression of HO-1 after endurance exercise are not completely clear, but a causal involvement of a cytokine-mediated generation of ROS must be discussed. We supposed that the down-regulation of the baseline expression of HO-1 in athletes reflects an adaptional mechanism to regular exercise training.

Adaptation, Physiological↗
PubMed1999

Differential expression of alpha2-6 sialylated polylactosamine structures by human B and T cells.

We found that human peripheral B and T cells differed in the surface expression of alpha2-6 sialylated type 2 chain glycans. In contrast to B cells, T cells expressed only sialoglycans with repeated N-acetyllactosamine (Galss1-4GlcNAc) disaccharides. This finding was based on the specificity of the monoclonal antibodies HB6, HB9 (CD24), HD66 (CDw76), FB21, and CRIS4 (CDw76) with the alpha2-6 sialylated model gangliosides IV6NeuAcnLc4Cer (2-6 SPG), VI6NeuAcnLc6Cer (2-6 SnHC), VIII6NeuAcnLc8Cer (2-6 SnOC), and X6NeuAcnLc10Cer (2-6 SnDC). We found that, in addition to their common requirement of an alpha2-6 bound terminal sialic acid for binding, the antibodies displayed preferences for the length of the carbohydrate backbones. Some of them bound mainly to 2-6 SPG with one N-acetyllactosamine (LacNAc) unit (HB9, HD66); others preferentially to 2-6 SnHC and 2-6 SnOC, with two and three LacNAc units, respectively (HB6 and FB21); and one of them exclusively to very polar alpha2-6 sialylated type 2 chain antigens (CRIS4) such as to 2-6 SnOC and even more polar gangliosides with three and more LacNAc units. These specificities could be correlated with the cellular binding of the antibodies as follows: whereas all antibodies bound to human CD 19 positive peripheral B cells, their reactivity with CD3 positive T cells was either nearly lacking (HD66, HB9), intermediate (about 65%: HB6, FB21) or strongly positive (CRIS4, 95%). Thus, the binding of the antibodies to 2-6 sialylated glycans with multiple lactosamine units appeared to determine their binding to T-cells.

Amino Sugars↗
PubMed1999

[Effect if 6-week nutritional intervention with enzymatic yeast cells and antioxidants on exercise stress and antioxidant status].

The aim of the present study was to investigate the influence of a yeast cell preparation rich in antioxidant vitamins, antioxidant enzymes, trace elements and minerals on the exercise-induced stress reaction and antioxidant status. The study was carried out in a non-blinded, controlled design. After a 6 week pre-ingestion period, 9 highly endurance-trained athletes took the preparation twice daily for another 6 weeks. After each phase venous blood samples were drawn in the resting state after an overnight fast followed by a strenuous 15 km cross country race. 1 h after the exercise venous blood sampling was repeated. Compared to the pre-ingestion period, the following significant alterations could be detected after 6 weeks of ingestion: 1) In the resting state, soluble interleukin-2 receptor (p < 0.05) and plasma fibrinogen (p < 0.01) were shown to be lower whereas plasma fibronectin was increased (p < 0.01). 2) 1 h after the race the significant difference in fibrinogen and fibronectin was confirmed. In addition myoglobin (p < 0.01) and CKMM3 (p < 0.05) as well as mangan superoxid dismutase (p < 0.05) were reduced. In conclusion, the 6-week ingestion-period resulted in an improvement of the systemic and muscular stress reaction. In addition, the decrease in mangan superoxide dismutase concentration can be interpreted as a sign of reduced free radical stress. However, these preliminary results have to be confirmed in larger trials in blinded designs. In addition, there seems to be a rationale for testing the effects of yeast-cell preparations in patients with chronic degenerative diseases as some of the investigated parameters are involved in the pathophysiology of such illnesses.

Adult↗
PubMed1999

Free radicals and oxidative stress in exercise--immunological aspects.

Reactive oxygen (ROS) and nitrogen species (RNS) are continuously generated in the biological system and play an important role in a variety of physiological and pathological processes. There is evidence that physical exercise augments the generation of ROS/RNS. The present review discusses and compares insights into the generation and function of ROS/RNS such as superoxide, hydrogen peroxide, hypochloric acid, and nitric oxide released by leukocytes in response to exercise. Emphasis is placed on: (a) mechanisms and regulation of ROS/RNS generation in immunocompetent cells with respect to acute exercise and regular training; (b) damaging effects of ROS/RNS in terms of oxidative stress which may be causally involved in features such as exercise-induced damage to muscle tissue and leukocyte DNA; (c) (immuno-) modulating effects of ROS/RNS which include activation of transcription factors; (d) responses of antioxidant stress proteins to acute exercise and regular training; and (e) effects of antioxidants on exercise-induced changes in immune function. Available data suggests that ROS/RNS are involved in the inflammatory response to heavy exercise and therefore exert damaging effects. Several immune functions are influenced by actions of ROS/RNS, and it is hypothesized that adaption to regular training is also modulated in part by free radicals. Furthermore, regular training seems to reduce the capacity of leukocytes for oxidant release and leads to an adaptation of antioxidative mechanisms, which may contribute to a limitation of exercise-induced oxidative stress.

Animals↗