Biomedical subjects

M Kuhn

Publications and source records attributed to M Kuhn.

At least 109 records · Page 6Linked to original sources

PubMed1996

Pituitary adenylate cyclase-activating polypeptide: a potent activator of human intestinal ion transport.

To investigate the effects of PACAP-27 on electrolyte transport across the isolated human intestinal mucosa, changes in short-circuit current (Isc) were measured in Ussing chamber experiments. Serosally added PACAP-27 increased Isc in a concentration-dependent manner, eliciting a similar maximal effect in both the jejunal and the colonic mucosa. Bumetanide inhibited Isc responses, indicating stimulation of Cl- secretion. The potency and efficacy of PACAP-27 were comparable to those of VIP, suggesting that both peptides activate intestinal secretion by way of a common receptor located in the basolateral membrane of the intestinal epithelium.

Colon↗

PubMed1996

[Liver injury caused by coumarin anticoagulants: experience of the IKS (Intercanton Monitoring Station) and the SANZ (Swiss Center for Drug Monitoring)].

Drug-induced liver diseases are potentially avoidable. Hepatotoxic drugs can mimic virtually any form of liver disease. Among all voluntary adverse drug reaction reports to central registries, 4-7% refer to drug-induced liver diseases. We analyze all cases of coumarin-induced hepatic injuries reported on a voluntary basis to the Swiss Drug Monitoring Centre (SANZ) and the Pharmacovigilance Centre (IKS) from 1981 to 1995. During this period the SANZ collected 9720 reports, 674 of which (6.9%) referred to the liver and the biliary tract. In only 11 reports an oral anticoagulant was involved. In 8 cases we assumed at least a possible causal relationship. 2 more cases were reported directly to the IKS. Among these 10 cases 7 were related to phenprocoumon and 3 to acenocoumarol. In 4 cases elevated concentrations of liver enzymes were measured 2-7 days after the beginning of therapy. In the remaining 6 cases the clinical picture was so severe that the patients had to be hospitalized. These 10 cases are discussed and compared with the cases published in the literature. According to our data, hepatic disorders induced by coumarin-anti-coagulants are rare. If hepatitis is diagnosed in a patient treated with oral anticoagulants, the differential diagnosis of a coumarin-induced hepatic injury has to be considered. Crossreactions between the coumarin derivatives phenprocoumon and acenocoumarol are possible.

Acenocoumarol↗

PubMed1996

[Ulcer drugs: profile of side effects of proton-pump blockers in comparison to H2 blockers in the spontaneous reporting system].

Inhibition of gastric acid secretion by drugs remains the most important rational approach to the treatment of acid related diseases. Histamine H2-antagonists and more recently the proton pump blockers have become the first line treatment for acid peptic diseases. Proton pump blockers bind specifically to the proton pump of the parietal cells and thus inhibit the final acid secretion independently from the activating stimuli. Because of this specific mechanism fewer adverse effects on other systems in the body are expected with proton pump blockers than with histamine antagonists. An analysis of the spontaneous reports which the Swiss Drug Monitoring Center (SANZ) received from 1981 to 1995 showed striking differences in the adverse drug reaction profile: hypersensitivity reactions with fever and anaphylactic reactions, liver disorders such as cholestatic hepatitis, most with severe progression and requiring hospitalization, as well as endocrine disorders were reported more frequently with histamine antagonists, skin reactions and joint disorders, however, were reported more often with proton pump blockers. Our data also support the conclusion that adverse drug reactions to proton pump blockers and histamine antagonists are rare in the spontaneous reporting scheme (reporting rate < 1%). There was a somewhat higher rate of serious reports with histamine antagonists. These data do not allow conclusions concerning long-term effects or effects with larger than recommended dosages.

Anti-Ulcer Agents↗

PubMed1996

[Thromboembolic events in women treated with hormones. Acute cerebrovascular thrombosis in 2 young women receiving ovulation inhibitors, and experiences of SANZ (Swiss Drug Monitoring Center) 1991-1995].

We describe 2 young patients with severe cerebrovascular thrombotic events whose only risk factor was intake of oral contraceptives. A 41-year-old woman suffered thrombosis of the basilar artery and remained disabled with a locked-in syndrome; a 23-year-old woman had thrombosis of the sinus sagittalis. These 2 cases and the current discussion regarding the use of hormones either as oral contraceptives or hormonal replacement therapy with estrogens and/or progestins prompted a review of the literature and a review of all spontaneous reports from 1991 to 1995 to SANZ (Schweizerische Arzneimittel-Nebenwirkungs-Zentrale), the Swiss Drug Side Effects Monitoring Center. The spontaneous reporting under this system does not allow conclusions on prevalence and incidence of adverse events. In these 5 years 33 vascular events associated with different hormones were reported. There were 28 reports of venous thrombosis of the lower and upper limb or pulmonary embolisms, and 5 reports of cerebrovascular complications. In 9 of 33 cases the hormones were used as hormonal replacement therapy and in 24 of 33 cases as oral contraceptives. In half of these women other risk factors for thromboembolic events such as overweight, family history of thrombosis and immobilization were known. Complications occurred with different preparations containing different estrogens and progestins. According to the literature, third generation progestins seem to involve a slightly increased risk of venous thromboembolism but a reduced risk of arterial thromboembolic events, which was confirmed by the SANZ data (17 of all 24 cases). Increasing age and rising estrogen dosage of oral contraceptives are associated with increased risk of vascular events. Although thromboembolic events also occur during hormonal replacement therapy with naturally occurring estrogens, the prophylactic potential of these drugs with regard to osteoporosis and cardiovascular events certainly outweighs this risk.

Adult↗

PubMed1996

[Drug-induced taste disorders].

Taste disorders may have diverse uncomfortable consequences such as reduced quality of life, weight loss and possibly professional disability. The sense of taste depends on many factors. Thus various conditions may cause taste disorders, drugs being one of them. The list of drugs being able to cause taste disorders as adverse drug reaction is long and there are many such cases reported to the Swiss Drug Monitoring Center (SANZ). The possibility of an unwanted side effect should be taken into account if a patient complains about taste disorders, such as reduced or changed sense of taste.

Adult↗

PubMed1996

[Side effects of drugs on the respiratory tract: experiences of the Swiss Drug Monitoring Center from 1991 to 1995].

Between 1991 and 1995 about 3% of the unwanted drug-induced side effects reported to the Swiss Drug Monitoring Center (SANZ) concerned pulmonary disturbances (144 out of a total of 4824 reports). The most frequent reports were those about cough and taste disorders caused by ACE-inhibitors, smell disorders caused by antimicotics, and asthma attacks caused by nonsteroidal antirheumatics or betablocking eye drops. 33% of these unwanted side effects have been classified as severe. By spontaneous reporting a correct calculation of incidence is not possible. The reports, however, have signal function. Precise case analysis, temporary correlations (reaction and exposure time and onset of reaction), exclusion of other causes for the disease, comparisons between similar cases and critical study of literature concerning drug-related side effects are still the most important foundations for diagnosis.

Drug Monitoring↗

PubMed1996

Site-directed mutations affecting the spectroscopic characteristics and midpoint potential of the primary donor in photosystem I.

Photosystem I is a member of the iron-sulfur center or type I reaction centers. The primary electron donor in photosystem I is a chlorophyll a dimer termed P700. The biophysical properties of P700 are well understood, but the protein environment that gives it such unique properties is unknown. We have characterized site-directed mutants of the photosystem I reaction center protein PsaB and identified an amino acid, His-656, that interacts closely with one of the P700 chlorophylls. Mutation of His-656 to Asn or Ser increases the oxidation midpoint potential of P700/P700+. by 40 mV. The P700/P700+. optical difference spectra show the appearance of a new bleaching band at 667 nm. Electron nuclear double resonance spectroscopy indicates a significant increase in the hyperfine coupling corresponding to methyl protons at position 12 of the spin carrying chlorophyll a of P700+. The implication of these results to current structural models of the photosystem I reaction center is discussed.

Amino Acid Sequence↗

PubMed1996

Effects of hydrogen bonding to a bacteriochlorophyll-bacteriopheophytin dimer in reaction centers from Rhodobacter sphaeroides.

The properties of the primary electron donor in reaction centers from Rhodobacter sphaeroides have been investigated in mutants containing a bacteriochlorophyll (BChl)--bacteriopheophytin (BPhe) dimer with and without hydrogen bonds to the conjugated carbonyl groups. The heterodimer mutation His M202 to Leu was combined with each of the following mutations: His L168 to Phe, which should remove an existing hydrogen bond to the BChl molecule; Leu L131 to His, which should add a hydrogen bond to the BChl molecule; and Leu M160 to His and Phe M197 to His, each of which should add a hydrogen bond to the BPhe molecule [Rautter, J., Lendzian, F., Schulz, C., Fetsch, A., Kuhn M., Lin, X., Williams, J. C., Allen J. P., & Lubitz, W. (1995) Biochemistry 34, 8130-8143]. Pigment extractions and Fourier transform Raman spectra confirm that all of the mutants contain a heterodimer. The bands in the resonance Raman spectra arising from the BPhe molecule, which is selectively enhanced, exhibit the shifts expected for the addition of a hydrogen bond to the 9-keto and 2-acetyl carbonyl groups. The oxidation--reduction midpoint potential of the donor is increased by approximately 85 mV by the addition of a hydrogen bond to the BChl molecule but is only increased by approximately 15 mV by the addition of a hydrogen bond to the BPhe molecule. An increase in the rate of charge recombination from the primary quinone is correlated with an increase in the midpoint potential. The yield of electron transfer to the primary quinone is 5-fold reduced for the mutants with a hydrogen bond to the BPhe molecule. Room- and low-temperature optical absorption spectra show small differences from the features that are typical for the heterodimer, except that a large increase in absorption is observed around 860-900 nm for the donor Qy band in the mutant that adds a hydrogen bond to the BChl molecule. The changes in the optical spectra and the yield of electron transfer are consistent with a model in which the addition of a hydrogen bond to the BChl molecule increases the energy of an internal charge transfer state while the addition to the BPhe molecule stabilizes this state. The results show that the properties of the heterodimer are different depending on which side is hydrogen-bonded and suggest that the hydrogen bonds alter the energy of the internal charge transfer state in a well-defined manner.

Amino Acid Sequence↗

PubMed1996

Fluorescent fiber-optic calcium sensor for physiological measurements.

A new optical sensor based on covalent immobilization of a newly synthesized calcium-selective, long-wavelength, fluorescent indicator has been constructed, with a response dynamic range optimal for physiological measurements. Immobilization occurs via photoinitiated copolymerization of the indicator with acrylamide on the distal end of a silanized 125 micrograms diameter multimode optical fiber. The working lifetime of this sensor is limited only by photobleaching of the indicator. Due to the inherent hydrophilic nature of the acrylamide polymer, the response time of this new sensor is governed by simple aqueous diffusion of the ionic calcium. This results in sensor response times fast enough to monitor some concentration fluctuations at physiological rates. The ability to monitor calcium concentration fluctuations in a high background level of magnesium is also demonstrated with a calculated selectivity of 10(-4.5).

Biosensing Techniques↗

PubMed1996

[Fulminant, rapidly reversible hepatitis and life-threatening anaphylaxis following rifampicin in an HIV-positive female patient with latent adrenal cortex insufficiency].

We report the case of a 28-year-old-prostitute from Thailand with HIV infection stage B2 associated with retroperitoneal lymph node tuberculosis. 6 days after the beginning of anti-tuberculous therapy (isoniazid, rifampicin, pyrazinamid and ethambutol) the temperature rose to 40.5 degrees C, diarrhea, vomiting, and tachycardia developed and systolic blood pressure fell to 80 mm Hg. Liver function tests revealed acute hepatic failure (ALT 800 IU/l rising to 1500; serum bilirubin 89 mumol/l rising to 238.0; alkaline phosphatase 199 IU/l; glucose 1.8 mmol/l; prothrombin time 20%). Isoniazid, rifampicin, and pyrazinamid were replaced by streptomycin and PAS. A few days after withdrawal the liver profile returned to normal. Hours after the reintroduction of rifampicin total body erythema, pruritus, vomiting and severe hypotension developed, requiring saline methylprednisolone and epinephrine administration. The next reexposure to intravenous rifampicin produced a rash and was rapidly discontinued. Liver function tests remained normal. Later mild adverse reactions to streptomycin and pyrazinamid occurred, two drugs which had been well tolerated before. Subsequently the diagnosis of adrenal insufficiency was established. After initiation of steroid replacement (50 mg prednisolone) the antituberculous therapy with isoniazid, pyrazinamid and ethambutol was well tolerated. We conclude that the shock in this HIV-infected patient was either due to severe anaphylaxis to rifampicin or acute adrenal insufficiency ensuing on this drug. The reversible fulminant acute hepatic failure represents either an adverse effect of antituberculous drugs, especially hepatotoxic interactions of drug combinations, or an ischemic liver injury during hypotension caused by anaphylaxis. The case illustrates the complex nature of side effects of antituberculous drugs in HIV patients and their aggravation by adrenal insufficiency.

Adrenal Insufficiency↗

PubMed1996

Topical anaesthesia for minor lacerations: MAC versus TAC.

OBJECTIVE: To determine whether a solution of bupivacaine Marcain [Astra]), adrenaline and cocaine (MAC) is as safe and effective as tetracaine, adrenaline and cocaine (TAC) as topical anaesthesia for wound suturing. DESIGN: Double-blind, randomised, prospective trial. SETTING: Emergency departments of two tertiary referral hospitals (one specialising in paediatric care) in Adelaide, South Australia, between February 1992 and April 1994. PARTICIPANTS: 181 patients, aged six or older, with simple dermal lacerations less than 5mm deep, not involving mucous membranes or areas with end-arterial blood supply. INTERVENTIONS: Patients received a weight-adjusted dose of either MAC or TAC. OUTCOME MEASURES: Needle-prick testing of wound for pain before suturing, pain ratings by patients and physicians during suturing, signs and symptoms of cocaine toxicity, wound complications and patient preference for topical anaesthesia. RESULTS: Topical anaesthesia was adequate for suturing in 73% of patients (83% or those with head wounds and 56% of those with extremity wounds). MAC and TAC did not differ significantly in efficacy overall or by wound location. Pain ratings from patients treated with MAC and TAC were comparable, as was patients acceptance of topical anesthesia (77%, MAC; 81%, TAC) and the incidence of adverse effects (4% infection rate overall). CONCLUSIONS: Topical anesthesia is a safe and effective means of anaesthetising selected lacerations for suturing. As we found no significant differences in either the efficacy or safety of the two solutions, we believe that MAC can be substituted for the less readily available TAC whenever expedient.

Adolescent↗

PubMed1996

Urinary excretion of urodilatin in patients with cirrhosis.

Cirrhotic patients with ascites show increased plasma levels of natriuretic peptides from cardiac origin (i.e., atrial natriuretic peptide [ANP] and brain natriuretic peptide [BNP]). Urodilatin is a unique member of the natriuretic peptide family because it is exclusively synthesized in the kidney acting on a paracrine fashion in the regulation of sodium excretion. To investigate the renal production of urodilatin in cirrhosis and its relationship with other natriuretic peptides and sodium retention, urodilatin excretion and plasma levels of ANP were measured in 21 healthy subjects, 13 cirrhotic patients without ascites and 23 cirrhotic patients with ascites. Urine urodilatin was measured with a highly specific radioimmunoassay using a polyclonal antibody against human urodilatin. Patients with ascites had marked sodium retention (UNa 7 +/- 2 mEq/d) as compared to patients without ascites and healthy subjects (29 +/- 3 mEq/d and 34 +/- 5 mEq/d, respectively, P < .001). Patients with cirrhosis and ascites had urine urodilatin excretion similar to patients without ascites and healthy subjects (82 +/- 8 pmol/g, 95 +/- 10 pmol/g, and 89 +/- 9 pmol/ g of creatinine, respectively; not significant). In addition, immunoreactive urodilatin from cirrhotic patients with ascites and healthy subjects showed a similar chromatographic pattern. By contrast, plasma ANP levels were increased significantly in patients with ascites (29 +/- 3 fmol/mL) as compared with patients without ascites or healthy subjects (14 +/- 3 fmol/mL and 6 +/- 1 fmol/mL, respectively; P < .01). In conclusion, urine urodilatin excretion is normal in patients with cirrhosis even in the presence of marked sodium retention. The coexistence of increased ANP levels and normal urodilatin excretion suggests that in cirrhosis both natriuretic peptides are regulated independently.

Aldosterone↗

PubMed1996

Localization, expression, and characterization of guanylin in the rat adrenal medulla.

The peptide guanylin, recently isolated from the intestine, and localized to cells of the gut mucosa, is involved in electrolyte/water transport in the intestinal epithelium by means of a paracrine mode of regulation. Since high amounts of this peptide are present also in the systemic circulation, we investigated the adrenal gland as a potential endocrine source of guanylin. Using a reverse transcriptase-polymerase chain reaction and hybridization with an internal oligonucleotide designed for rat guanylin, 514-bp signals were obtained in intestinal tissue and adrenal gland. Successive analyses of extracts from intestine and adrenal gland by HPLC, western blotting, and radioimmunoassay revealed the presence of the same high-molecular mass (about 12.4 kDa) guanylin that corresponds to the mass of the guanylin prohormone. About 60 fmol/ml of circulating immunoreactive guanylin was determined in plasma. Localization studies with antisera directed against different epitopes of guanylin revealed that, in the adrenal gland, guanylin immunoreactivity is restricted to the medulla, where it is mainly confined to norepinephrine chromogranin A-containing cells. On the ultrastructural level, guanylin immunoreactivity was exclusively located to secretory granules of chromaffin cells. The present data indicate that, in addition to entero-endocrine cells, the adrenal medulla represents a further source of guanylin. Thus, an endocrine mode of function of guanylin may accrue to its hitherto evidenced paracrine action in fluid transport in the intestinal epithelium. Furthermore guanylin may be considered as a neurohormonal peptide.

Adrenal Medulla↗

PubMed1996

Extensible biosignal (EBS) file format: simple method for EEG data exchange.

Increasing use of computer technology in EEG research requires the creation of standardized data formats to transmit, exchange, analyze or modify mainly EEG/MEG as well as mere general polygraphic data. The extensible biosignal file format (EBS) has been designed for easy use. The concept of the EBS format is a simple structure of variable size, consisting of one fixed and two variable headers and a data section. In the variable header, any information can be stored in attributes. The data are archived in one of 3 organizational forms: channel order, temporal order, or compressed. The format supports various data types, multiple biosignals (ECG, EEG, MEG, polygraph), annotations, processing history, location diagrams (CGM), 16 hit ISO 10646 character set, random access to large amounts of data, global or private extensions, self-identification, and multiple tools for conversion, modification and visualization which are freely available in source code.

Brain↗

PubMed1996

Guanylin strongly stimulates rat duodenal HCO3- secretion: proposed mechanism and comparison with other secretagogues.

BACKGROUND & AIMS: Guanylin and heat-stable enterotoxin (STa) stimulate intestinal Cl- secretion via activation of the cystic fibrosis transmembrane regulator (CFTR)-encoded Cl- channel. It was speculated that CFTR activation also regulates electrogenic duodenal HCO3- secretion. Therefore, the effect of guanylin/STa and other secretagogues on rat duodenal HCO3- secretion was studied. METHODS: The HCO3- secretory rate of in vitro rat proximal duodenum was determined by pH stat titration and paracellular permeability by 3H-mannitol fluxes, bidirectional 36Cl- fluxes were measured, and the short-circuit current (Isc) was recorded. RESULTS: Luminal guanylin and STa concentration dependently stimulated the HCO3- secretory rate and Isc. Guanylin-stimulated HCO3- secretion was independent of luminal Cl-, inhibited by the Cl- channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoate, and additive to the HCO3- secretory rate stimulated by glucagon and carbachol but not by the tested adenosine 3',5'-cyclic monophosphate (cAMP)-dependent agonists. The ratio of the HCO3- secretory rate/Isc stimulated by the tested guanosine 3',5'-cyclic monophosphate (cGMP)-dependent agonists was markedly higher than the cAMP-dependent agonists. Prostaglandin E2 and 8-bromo-cAMP but not STa/guanylin also transiently increased paracellular permeability. CONCLUSIONS: Guanylin and STa stimulate electrogenic HCO3- secretion in rat duodenum, most likely via CFTR Cl- channel activation, but the different relationship for HCO3- to Isc in cGMP-than in cAMP-stimulated anion secretion suggests a different cellular source and/or signaling pathways.

Animals↗

PubMed1996

Recombinant human erythropoietin enhances vasoconstrictor tone via endothelin-1 and constrictor prostanoids.

Hypertension is the main side effect developing in patients suffering from renal anemia who are treated with recombinant human erythropoietin (rHuEPO). We investigated the effect of rHuEPO on the vascular tone of isolated rabbit aorta and carotid artery under isometric conditions. The production of prostacyclin and the vasoconstrictor prostanoids PGF2 alpha and TXB2 was investigated in arterial rings incubated with rHuEPO. Endothelial cells from human umbilical veins (HUVECs) were isolated and cultured in flasks (37 degrees C, 5% CO2). After incubation with rHuEPO, the formations of prostacyclin (as its stable metabolite 6-keto-PGF1 alpha), PGF2 alpha, PGE2, thromboxane (TX) B2 and of ET-1 were measured by radioimmunoassays. rHuEPO had no direct vasoconstrictor effect, but it enhanced noradrenalin-induced contractions. This effect was more prominent in rings with intact endothelium than in rings from which the endothelium had been mechanically removed, indicating that endothelial vasoactive factors might be involved. Relaxations to acetylcholine (ACh, 1 microM) were unaltered in the presence or absence of rHuEPO, suggesting that the endothelial NO-cGMP pathway was not impaired by rHuEPO. Incubation with rHuEPO (20 to 200 U/ml) increased the release of the vasoconstrictor mediators ET-1, PGF2 alpha and TXB2, and decreased prostacyclin formation in isolated rabbit arterial rings and in HUVECs, respectively. The cyclooxygenase inhibitor indomethacin abolished the rHuEPO-induced increase in vasoconstrictor prostanoid production. ET-1 formation by HUVECs was also increased by rHuEPO in a dose-dependent manner (maximal effect +90% by rHuEPO 200 U/ml, P < 0.05). Indomethacin and the selective ETA receptor antagonist BQ123 each partly inhibited the enhancement of vascular responsiveness to noradrenalin induced by rHuEPO in rabbit carotid artery, but simultaneous administration of rHuEPO with both antagonists completely abolished the force increment. In conclusion, these studies show that a dose-dependent shift in the balance of constrictor and relaxing prostanoids as well as an increased synthesis of ET-1 induced by rHuEPO lead to the enhanced vascular responsiveness to noradrenalin in isolated rabbit arteries. The increased vascular responsiveness to noradrenalin, which is in line with clinical observations, may contribute to the hypertensive side effect associated with rHuEPO therapy in patients with chronic renal failure.

Acetylcholine↗

PubMed1996

Genetic markers linked to quantitative traits in poultry.

This study utilized DNA fingerprints and crosses of two genetically distinct lines of layer-type chickens to identify genetic markers linked to quantitative trait loci (QTL). In phase I, backcross (BC1) hens were separately ranked for each of eight traits and then blood pools were produced in groups along each phenotypic distribution. The DNA was isolated from the blood pools and used in a gradient analysis to screen for DNA fingerprint bands that exhibited intensity gradients associated with the phenotypic traits. To identify linkage of bands with QTL and to estimate band effects, F2 progeny were produced in phase II from the phase I BC1 population. A single-trait animal model was used for analysis of associations of all individual DNA fingerprint bands of sires and their progeny phenotypic performance. Twenty fingerprint bands, only two of which had shown trait-associated gradients in phase I, were identified by the animal model analysis of the progeny test as QTL linked (P < or = 0.05) to specific traits of growth, reproduction and egg quality. These 20 bands warrant further study as potentially valuable molecular markers for QTL.

Animals↗

PubMed1996

Differential regulation of cytokine and cytokine receptor mRNA expression upon infection of bone marrow-derived macrophages with Listeria monocytogenes.

Cytokine and cytokine receptor mRNA expression was analyzed by PCR-assisted amplification of RNA extracted from bone marrow-derived macrophages (BMM phi) at different time points after infection with Listeria monocytogenes. The mRNAs for the cytokines interleukin-1 alpha (IL-1 alpha), IL-1 beta, and tumor necrosis factor alpha (TNF-alpha) were induced early after infection, whereas IL-6 mRNA appeared later and even nonhemolytic Listeria strains, which are unable to grow inside eukaryotic cells, induced the same cytokine mRNAs at levels similar to those of the wild-type strain. In most cases, the amounts of cytokines determined by various bioassays correlated with the level of mRNA induction. Inhibition of phagocytic uptake of L. monocytogenes by cytochalasin D treatment resulted in adherent bacteria which still induced the proinflammatory cytokines. In BMM phi, the level of IL-1 receptor II mRNA was unaffected, whereas mRNA expression of the two subtypes of tumor necrosis factor receptors (TNF-RI and TNF-RII) was differentially regulated upon infection: transcription of TNF-RI was reduced, and that of TNF-RII mRNA was induced. Similar to the decreased TNF-RI mRNA expression, gamma interferon receptor mRNA was downregulated in L. monocytogenes-infected BMM phi. This dose- and time-dependent induction or downregulation of cytokine receptor mRNA following L. monocytogenes infection of BMM phi was not observed upon infection of established macrophage-like cell lines J774 and P388D1. Induction of IL-6 mRNA as well as IL-1 alpha/beta and TNF-alpha mRNAs upon L. monocytogenes infection of BMM phi occurs independently of autocrine TNF-alpha signaling via TNF-RI or TNF-RII, as shown by infection of TNF-RI- and TNF-RII-deficient macrophages derived from mutant B6 x 129 mice. In contrast to gamma interferon receptor mRNA, both TNF receptor subtype mRNAs were not influenced by L. monocytogenes infection of hybrid (B6 x 129) mouse macrophages. Whereas the proinflammatory cytokine mRNAs were even induced after infection with the nonpathogenic species L. innocua, no alteration of cytokine receptor mRNA expression was observed after challenge of BMM phi with this nonpathogenic species, suggesting that the modulation of cytokine and cytokine receptor expression by L. monocytogenes could be an important way of inhibition of macrophage stimulation.

Animals↗