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H Northoff

Publications and source records attributed to H Northoff.

At least 19 recordsLinked to original sources
PubMed2001

Induction of iNOS in human monocytes infected with different Legionella species.

The contribution of nitric oxide (NO) radicals to the suppression of intracellular replication of Legionella has been well established in rodents but remained questionable in humans. Considering the fact that human monocytes do not exhibit a high-output NO production, we used sensitive methods such as detection of inducible NO synthase (iNOS) mRNA by reverse transcription-PCR and demonstration of iNOS protein expression by means of flow cytometry and Western blot to compare the levels of iNOS induced by Legionella species which, in accordance to their human prevalence, show different multiplication rates within human monocytic cells. The expression of iNOS in Mono Mac 6 (MM6) cells showed an only moderate inverse correlation to the intracellular replication rate of a given Legionella species in the protein expression assays. However, stimulation of host cells with 1,25-dihydroxyvitamin D(3) to enhance NO production and inhibition of NO production by treatment of host cells with N(G)-methyl-L-arginine were not able to modify the intracellular multiplication of legionellae within MM6 cells. Therefore, NO production does not seem to play a crucial role for the restriction of intracellular replication of Legionella bacteria within human monocytic cells. Rodent models in investigations which are supposed to clarify the involvement of NO radicals in defense mechanisms against Legionella infections in humans are of doubtful significance.

Animals↗
PubMed2001

Time-related changes of collected shed blood in autologous retransfusion after total knee arthroplasty.

A prospective study was done to determine the changes in blood quality parameters of collected drainage blood in retransfusion systems at 6 and 12 h after surgery to verify whether the blood was still suitable for retransfusion purposes for an additional 6 postoperative hours beyond the so far accepted first 6-h time window after surgery. Eighty-one patients received retransfusion within the first 6 h immediately following total knee arthroplasty. Additionally, drainage blood was collected for another 6 h using the same retransfusion system. Samples for laboratory analysis were taken from both the first and second 6-h blood collection interval. Hemoglobin values increased from 9.6 to 10.4 g dl(-1) (p = 0.021). Platelet counts increased from 65,500 to 80,900 microl(-1) (p < 0.001). Leukocyte counts increased from 5,550 to 8,190 1(-1) (p < 0.001). Lactate dehydrogenase (672 U l(-1) during the first vs 651 U l(-1) during the second collection period) and free hemoglobin (71.7 mg dl(-1) vs 67.0 mg dl(-1)) did not change significantly. The potassium concentration decreased slightly from 4.33 to 4.20 mg dl(-1) (p = 0.002). The lactate concentration increased from 4.44 to 7.21 mg dl(-1) (p < 0.001). The pH decreased from 7.07 to 6.94 (p < 0.001). Interleukin-6 concentration increased from 6,500 to 46,500 ng l(-1) (p < 0.001). In this study, we found no relevant difference in most of the drainage blood quality parameters between the first 6-h collection period and the second 6-h collection with regard to its suitability for autologous retransfusion except higher interleukin-6 levels. Due to the higher interleukin concentration, a possible increase in febrile reactions should be taken into account during retransfusion.

Aged↗
PubMed2001

Artificial oxygen carriers--the new doping threat in endurance sport?

Maximal oxygen uptake is the major performance limiting factor in endurance sports. Sophisticated training methods have been developed to increase this variable. On the other hand, attempts have been made to improve maximal oxygen uptake by artificial means: blood doping and the misuse of recombinant human erythropoietin have beneficial effects on aerobic exercise capacity. Both methods have been banned by international sporting federations. A new class of substances might represent the next step of fraudulent improvement of the maximal oxygen uptake: artificial oxygen carriers, such as solutions based on recombinant, bovine or human hemoglobin and perfluorocarbon-emulsions have been shown to improve oxygen delivery to the muscle. Hemoglobin-based solutions improve aerobic exercise capacity in animal and human testing. Both substances have potentially lethal side effects including renal toxicity, increased systemic and pulmonary blood pressure and impairment of the immune system. Hemoglobin-based carriers can be detected in drug testing with routine laboratory tests based on the detection of free hemoglobin. Perfluorocarbon is not metabolized by the body and exhaled through the lung and can be measured with chromatography. No screening for these substances in drug tests has been performed so far. International sporting federations should be aware of this new, emerging doping threat.

Biological Transport↗
PubMed2001

Increased interleukin-6 in collected drainage blood after total knee arthroplasty: an association with febrile reactions during retransfusion.

We determined interleukin-6 (IL-6) concentrations in collected shed drainage blood intended for retransfusion in a prospective study in 81 patients after total knee replacement. We found large increases in IL-6 levels, averaging 6.5 (SD 3.9) ng/mL, in shed blood collected in the first 6 postoperative hours. 3 patients had febrile reactions after collected blood was retransfused. The IL-6 levels in the drainage blood of these patients were very high (9.6-13.4 ng/mL). In the blood collected after 6 hours, IL-6 concentrations increased to 47 (SD 33) ng/mL (p < 0.001). These results suggest a relation between increased interleukin-6 concentrations in shed drainage blood and the occurrence of febrile reactions after retransfusion of such blood.

Aged↗
PubMed2001

A system establishment compatibility profiles for artificial oxygen carriers and other substances.

Worldwide, great efforts are being made to develop a clinically useful artificial oxygen carrier. Toxicological and immunological compatibility is generally tested using animal experiments but inflammatory parameters in particular show large species-specific differences. Therefore, we developed an in vitro system using human components to establish a compatibility profile of unknown compounds. The test system comprises induction of hemolysis, activation of complement (C3a), induction/suppression of cytokine production, influence on cell proliferation, direct toxicity on peripheral leukocytes, and phagocytosis of the material under test and of microbes. The test system will be described, along with results of various perfluorocarbon emulsions. When testing lecithin-based perfluorodecalin (PFD) emulsions, and comparing them to Pluronic-based PFD emulsions, we could show that Pluronic-based emulsions were virtually untoxic to peripheral human leukocytes. They neither inhibited cell proliferation nor caused any hemolysis, but caused mild to moderate inhibition of endotoxin-induced cytokine production. At the same time, lecithin-based PFD emulsion caused substantial cytotoxicity in phagocytic cells like monocytes (60-100% after 24 h incubation) and granulocytes (10-20% after 24 h incubation). They also suppressed endotoxin-induced cytokine production in monocytes to more than 98% and inhibited cell proliferation of an endothelial (ECV 304) and a monocytic cell line (MonoMac6) to more than 95%.

Blood Substitutes↗
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↗