γ/δ Receptor-expressing T-cell clones from a cutaneous T-cell lymphoma suppress hematopoiesis

Summary Recently we described a cutaneous T-cell lymphoma expressing the / T-cell receptor [5]. The patient suffering from this lymphoma showed low numbers of myeloid and T cells in peripheral blood, while B and NK cells were relatively increased. In vitro culture of the patient's bone marrow (BM) cells revealed a significant suppression of myeloid/monocyte colony formation (GM-CFU) compared with normal controls. This was not due to infiltration of the BM with lymphoma cells. We speculated that a soluble factor either secreted or induced by the lymphoma cells might be responsible for the marked suppression of hematopoiesis in this patient. From a skin biopsy with infiltrating / T-lymphoma cells we established T-cell clones bearing the / T-cell receptor and resembling the phenotype of the lymphoma cells. The supernatant (SN) of these / T-cell clones reduced the number of colonies in a CFU-GM assay (using normal control BM) in comparison to SN of / T-cell clones established from the same biopsy. This suppression was seen mainly on day 7 of culture and was not neutralized by the addition of placenta-CM. The main mediator of this suppression seems to be IFN-,since it was detectable in high amounts in the SN of these / T-cell tumor clones as well as in the serum of the patient. In addition, anti-IFN- antibodies can reverse the T-cell SN-mediated suppression of CFU-GM. We conclude that high serum levels of interferon-, which is secreted in high amounts from / T-cells grown from a biopsy of a cutaneous lymphoma, can suppress hematopoiesis.Abbreviations TCR T-cell receptor - IFN- interferon- - SN supernatant - placenta CM placenta conditioned medium - BM bone marrow - CFU-GM myeloid/monocyte colony formation - NK cells natural killer cells - Ab antibody M. Wilhelm was supported by theDeutsche Forschungsgemeinschaft (DFG Wi 728-2)     

Comparing a high-dose dipyridamole SPECT imaging protocol with dobutamine and exercise stress testing protocols. Part III: Using dobutamine to determine lung-to-heart ratios, left ventricular dysfunction, and a potential viability marker

Determination of the severity of coronary artery disease (CAD) by single photon emission computed tomography (SPECT) imaging has previously been shown to have greater sensitivity, specificity, and accuracy when performed with pharmacologic stress using dobutamine than by standard dose dipyridamole (SDD) or exercise stress testing (EST) prior to SPECT imaging. The use of lung to heart (L:H) ratios has been shown to be valuable in determining the presence or absence of left main (LM) or triple vessel (3V) CAD. No such work has been previously reported for dobutamine. Twenty-one patients were studied using dobutamine (n=7) or EST (n=14). These results were compared with results from Part II of this series of studies using high-dose dipyridamole (HDD) pharmacologic stress. In this study, patients underwent L:H ratio analysis following injection of 3 mCi of Tl-201, this provides sufficient time for thallium clearance from the blood pool. Results of the L:H ratios were compared with the results of coronary arteriographic (CA) evaluation. Patients who were stressed via EST demonstrated statistically greater (p0.001) L:H ratios in patients with LM/3V CAD when compared with patients who had 0–2 significantly stenosed coronary arteries. Patients stressed with dobutamine demonstrated lower L:H ratios (p=NS) in patients with LM/3V CAD than was seen for patients with 0–2 V CAD. Patients stressed with dobutamine had statistically (p0.05) lower L:H ratios than did similar patients stressed with EST. Increased L:H ratios following EST and HDD, as shown previously in Part II of this series, provide excellent markers for LM/3V CAD following Tl-201 injection. The presence of normal L:H ratios in patients with LM/3V CAD following dobutamine stress may suggest the presence of stunned or hibernating myocardium. The presence of decreased L:H ratios following dobutamine after HDD or EST has already shown an increased L:H ratio, might suggest a marker for myocardial viability that deserves further investigation.Presented in part at the 39th Annual World Congress International College of Angiology, Istanbul, Turkey, June 1997.     

A sensitive double antibody radioimmunoassay for Human Growth hormone (HGH): levels of serum HGH following rapid tolbutamide infusion

Summary A double antibody radio-immunoassay for human growth hormone is described. — The assay can detect 0.0625 mg HGH/ml serum and has good reproducibility. It was found that: 1. a highly pure labelled hormone; 2. a specific and very potent guinea pig antihuman growth hormone antibody; and 3. at least five days of incubation for the first reaction were necessary to achieve this accuracy and sensitivity. -Porcine and rat growth hormone, sera from cow, guinea pig, rabbit, mouse, and toad fish did not react with the guinea pig anti-HGH serum used in the assay. — In four patients after hypophysectomy, HGH concentrations disappeared almost completely, and in another patient no rise of the hormone was seen during an IV insulin tolerance test.-Undiluted human serum appears to produce falsely high levels of HGH. — Normal males exhibited fasting HGH levels from 0 –2.2 mg/ml (mean 0.8 mg/ml). Females ranged from 0.6–15.0 mg/ml (mean 5.1 mg/ml) and 15 acromegalics from 8.0–103.0mg/ml (mean 31.2 mg/ml). — During a rapid tolbutamide tolerance test, serum HGH rose between 2.5- and 82-fold over the fasting levels within 10 to 70 minutes following the glucose nadir.Performed in part during a postdoctoral fellowship Stiftung Volkswagenwerk, Germany.     

Modulation of pacemaker activity in sheep cardiac Purkinje fibers by stimulation of β-adrenoceptor subtypes

The electrophysiological effects mediated by ₁- and ₂- in spontaneously active sheep cardiac Purkinje fibers were investigated using the non-selective agonist (–)-isoproterenol (IPN) and the selective agonists (–)-noradrenaline (₁) and procaterol (₂) in the absence and presence of the selective antagonists bisoprolol (₁) and ICI 118,551 (₂).IPN (0.01 mol/l) increased the spontaneous rate by 54% and the slope of diastolic depolarization by 68% of the respective control values. Further, IPN increased the action potential duration at –20 mV (APD –20 mV) from 96 to 154 ms, reduced the APD –70 mV by 17% and the duration of the diastole by 39% and slightly hyperpolarized the maximum diastolic potential. These effects were partially inhibited by ICI 118,551 (0.03 mol/l), diminished by bisoprolol (0.1 mol/l) and almost completely blocked by the combination of both antagonists. Concentration response curves of IPN were influenced by the selective antagonists as follows: ICI 118,551 (0.03 mol/l) shifted the curves to the right by 0.2–0.4 log units and increased the slope factor. Bisoprolol (0.1 mol/l) induced a greater shift to the right by 1.1–1.5 log units. Combination of bisoprolol with ICI 118,551 shifted the curves to the right by 1.5–1.7 log units.Noradrenaline (0.3 mol/l) elicited similar actions as IPN. Bisoprolol (0.1 mol/l) shifted the concentration response curves of noradrenaline to the right by 1.1–1.9 log units. Actions of procaterol (0.1 mol/l) were weak, attained only 15–35% of the maximal effects of IPN and could be blocked by ICI 118,551 (0.03 mol/l).These results show that the increase of pacemaker activity induced by catecholamines in sheep cardiac Purkinje fibers is predominantly mediated by stimulation of ₁. However, contribution of ₂ mediated effects could be demonstrated.Supported by Ministerium für Wissenschaft und Forschung, Nordrhein-Westfalen, Projekt-Nr, 40008786.     

Expression of adhesion molecules on acute leukemic blast cells and sensitivity to normal LAK activity

Summary Antigenic expression of CD54 and CD58 adhesion molecules was investigated on leukemic blast samples from ten patients with acute lymphoblastic (ALL) and 14 with acute myeloblastic (AML) leukemia. The mean intensity of fluorescence (MIF) was calculated and correlated with sensitivity of blast cells to the lytic activity of allogeneic lymphokine-activated killer (LAK) cells. CD54 antigen was expressed in all AML cases with an MIF of 11.2 while in ALL, though present in the majority of cases, it was absent in one case and expressed in less than 30% of blasts in two others, with an overall MIF of 3.0. CD58 expression was similar in both groups of patients, with an MIF of 7.6 in ALL and 7.0 in AML. In addition, in six of the ten ALL cases and in two of the 14 AML cases, leukemic blasts proved to be resistant to the cytotoxic activity of normal allogeneic LAK effectors. In these LAK-resistant patients, the CD54 antigenic expression was lower (p=0.03) than in LAK-sensitive patients with an MIF of 1.7 vs 4.9 in ALL and 1.35 vs 12.9 in AML cases. Finally, blocking of CD54 and/or CD58 receptors on leukemic blasts resulted in a slight reduction of⁵¹Cr release. Findings suggest that CD54 is differently expressed on myeloid and lymphoid blasts and that there is a correlation between CD54 MIF and susceptibility of blasts to the LAK activity.     

Analytical Performance of the New Coagulation Monitoring System INRatio™ for the Determination of INR Compared with the Coagulation Monitor Coaguchek® S and an Established Laboratory Method

An evaluation of the INRatio Prothrombin Time Monitoring system for determination of INR was done in two centers with a total of 5 healthy subjects and 77 subjects on oral anticoagulation. The INRatio and the Coaguchek® S were compared with an established laboratory method. The correlation coefficient of the comparison with the laboratory was r = 0.954 for INRatio and r = 0.937 for Coaguchek® S. The mean relative deviation from the lab method calculated according to Hill was 6.87% for INRatio, which is rated very goo, and 9.72% for Coaguchek® S (goo). The imprecision in the normal range (INR = 1.1) showed a coefficient of variation (CV) of 7.8% and a standard deviation (SD) of 0.09. In the therapeutic range (INR 3.9) the CV was 5.4%, the SD 0.21 and above therapeutic range (INR 5.3), the CV was 8.4% (SD 0.44), rated satisfactory. The concordances of the compared methods with the routine were 81% for INRatio and 79% for Coaguchek® S, which is considered state-of-the-art. Most of the patients perceptions of the INRatio were very positive.In the hands of professionals the INRatio demonstrated very good accuracy and precision and an excellent technical reliability. Further studies using INRatio for self testing by patients are warranted.     

Impaired cytokine production in whole blood cell cultures of patients with urological carcinomas

The production of the cytokines interferon (IFN ), interleukin-1 (IL-1 ) and tumor necrosis factor (TNF ) was investigated in the mitogen-stimulated whole blood cell culture media from 51 patients with urinary bladder carcinomas, 52 patients with renal carcinomas, 31 patients with prostatic carcinomas and 360 healthy controls. The cytokines were measured 4 days after induction by a sensitive enzymo-immunological assay. In the blood cell culture supernatants of the patients with urinary bladder carcinomas significancy lower levels of IFN (P0.001), IL-2 (P0.001) and TNF (P0.05) were found as compared to the controls. Blood cells of patients with renal carcinomas had lower production of IFN (P0.01), IL-2 (P0.001) and IL-1 (P0.01), whereas the values of the total group of patients with prostatic carcinomas were not significantly different from those of the controls. Lymphocyte and monocyte counts were almost identical in the control and all tumor patient groups. When the patients with renal carcinomas and prostatic carcinomas were analyzed according to their different clinical stages we could show a gradual depression of the IFN- levels, which was related to tumor burden.Abbreviations PHA phytohemagglutinin - PWM pokeweed mitogen - ELISA enzyme-linked immunoassay - IL interleukin - IFN interferon - TNF tumor necrosis factor, mAb, monoclonal antibody     

Dopamine in gastrointestinal disease

Dopamine is an important enteric neuromodulator. Herein we review the data that support a role for dopaminergic involvement in experimental duodenal and gastric ulceration; gastric, pancreatic, and duodenal secretion; gastrointestinal motility; and gastric and intestinal submucosal blood flow regulation. There also is support for a role for dopamine and dopamimetic agents in the treatment of certain experimental gastrointestinal diseases because some highly selective dopamine agonists are gastroprotective when given either parenterally or centrally. Based upon these observations, we suggest that dopamine is a key element of the brain-gut axis and represents a potentially important target for pharmacotherapeutic exploitation.Supported by grants from the Medical Research Council of Canada and the Faculty of Medicine Development Fund (G.B.G.) and the National Institutes of Health (S.S.).     

Expression and prognostic roles of integrins and interleukin-1 receptor type I in patients with ductal adenocarcinoma of the pancreas

To Investigate the prognostic indicator, we examined the expression of ₆- and ₅- integrin and interleukin-1 receptor type I (IL-1RI) immunohistochemically, and analyzed the correlation between immunohistochemical findings and clinicopathological factors in pancreatic cancer. In patients with a strongly expressing ₆- integrin subunit or weakly expressing ₅₁-integrin in pancreatic cancer tissues there was a significant association with advanced TNM stage (P = 0.027 and 0.014, respectively), presence of liver metastases (P = 0.032 and 0.002, respectively), and poor prognosis (P = 0.0155 and 0.0056, respectively). In patients with a weakly expressing ₆ integrin subunit or weakly expressing ₅₁-integrin in noncancerous pancreatic tissues there was a significant association with poor prognosis (P = 0.0324 and 0.0396, respectively). Multivariate analysis demonstrated that strong expression of ₆- and weak expression of ₅₁-integrin were found to be independent prognosticators in pancreatic cancer patients. Our present results indicate that ₆₁- and ₅₁-integrin expression can be a significant prognostic indicator in pancreatic cancer.     

Weakened cellular scavenging activity against oxidative stress in diabetes mellitus: regulation of glutathione synthesis and efflux

Summary Glutathione functions to scavenge oxidants or xenobiotics by covalently binding them and transporting the resulting metabolites through an adenosine 5-triphosphate-dependent transport system. It has been reported that the intracellular concentration of glutathione decreases in diabetes mellitus. In order to elucidate the physiological significance and the regulation of anti-oxidants in diabetic patients, changes in the activity of the glutathione-synthesizing enzyme, -glutamylcysteine synthetase, and transport of thiol [S-(2,4-dinitrophenyl)glutathione] were studied in erythrocytes from patients with non-insulin-dependent diabetes and K562 cells cultured with 27 mmol/l glucose for 7 days. The activity of -glutamylcysteine synthetase, the concentration of glutathione, and the thiol transport were 77%, 77% and 69%, respectively in erythrocytes from diabetic patients compared to normal control subjects. Treatment of patients with an antidiabetic agent for 6 months resulted in the restoration of -glutamylcysteine synthetase activity, the concentration of glutathione, and the thiol transport. A similar impairment of glutathione metabolism was observed in K562 cells with high glucose levels. The cytotoxicity by a xenobiotic (1-chloro-2,4-dinitrobenzene) was higher in K562 cells with high glucose than in control subjects (50% of inhibitory concentration. 300±24 mol/l vs 840±29 mol/l, p<0.01). Expression of -glutamylcysteine synthetase protein was augmented in K562 cells with high glucose, while enzymatic activity and expression of mRNA were lower than those in the control subjects. These results suggest that inactivation of glutathione synthesis and thiol transport in diabetic patients increases the sensitivity of the cells to oxidative stresses, and these changes may lead to the development of some complications in diabetes mellitus.Abbreviations ATP Adenosine 5-triphosphate - NIDDM non-insulin-dependent diabetes mellitus - GSH -glutamylcysteinyl glycine - GSSG glutathione disulphide - -GCS -glutamylcysteine synthetase - mRNA messenger ribonucleic acid - DNA deoxyribonucleic acid - C₅₀ 50% inhibitory concentration - CDNB 1-chloro-2,4-dinitrobenzene - GS-DNP S-(2,4-dinitrophenyl)glutathione - PSL photostimulated luminescence     

Inhibition ofO 6-alkylguanine-DNA alkyltransferase and DNase I activities in vitro by some alkylating substances and antineoplastic agents

Summary The specificities of the DNA repair enzymeO ⁶-alkylguanine-DNA alkyltransferase from brain and liver cells of the chick embryo and of DNase I were demonstrated in vitro by their response to substrate DNA pretreated with monofunctional alkylating agents of differentO ⁶-guanine alkylating ability and some antineoplastic agents. Treatment of DNA with ethidium bromide, Hoechst 33258, doxorubicin, Fe²⁺/bleomycin, and suramin resulted in a dose-dependent diminution of alkyltransferase activity (DE₅₀ 5 g/ml, 15 g/ml, 5 g/ml, 5 g/ml, 100 g/ml, respectively). Apart from bleomycin, comparable results were obtained with DNase I. Thermal denaturation of the substrate DNA reduced both alkyltransferase and DNase I activity. No effect was seen with X-irradiation. Cisplatin decreased only DNase I activity. Some topoisomerase II and/or gyrase inhibitors remained without significant effects on the alkyltransferase reaction whereas DNA catabolism by DNase I was diminished in a dose-dependent manner (DE₅₀ between 6.5 and 19 g/ml).Abbreviations AT alkyltransferase - BB bisbenzimide - EB ethidium bromide - DOX doxorubicin - CDDP cis-diamminedichloroplatinum (II) - MMS methylmethanesulphonate - EMS ethylmethanesulphonate - MNU methylnitrosourea - ENU ethylnitrosourea     

Vertebral osteomyelitis mimicking chronic pancreatitis

Summary Vertebral osteomyelitis rarely mimics pancreatitis. However, the potential consequences of longstanding unrecognized disease, including neurological impairment and bony deformity, should make it an item in the differential diagnosis of chronic pancreatitis. In the evaluation of our patient, four items were of particular importance: awareness of his previously documentedS. aureus bacteremia, a markedly elevated ESR, an abnormal chest radiograph, and the positive bone scan.Presented under the title Vertebral Osteomyelitis Mimicking Chronic Pancreatitis: Case Report and Literature Review at the annual meeting of the American College of Gastroenterology, October 16–18, 1995, New York, New York.     

An auto-anti-B in an A1B person. Serological studies

Summary The serum of a patient (Mr. Lat) with the regular blood group A₁B contains an anti-B reacting with all cells having a B antigen except b_x and cis AB. The anti-B reacts at 4° C and occasionally at room temperature as shown by agglutination, absorption-elution and by thermo-dynamic assays. The antibody is regarded as an irregular autoantibody belonging to the group of the so called suppressed or latent antibodies.

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Zusammenfassung Das Serum eines Patienten (Mr. Lat) mit der normalen Blutgruppe A₁B enthält Anti-B, das mit allen Zellen reagiert, die ein B-Antigen aufweisen, ausgenommen B_x und cis AB. Das Anti-B reagiert bei 4° C und gelegentlich bei Zimmertemperatur, was durch Agglutination, Absorption-Elution und durch thermodynamische Unter-suchungen gezeigt wurde. Der Antikörper wird als irregulärer Autoantikörper angesehen, der zur Gruppe der supprimierten oder latenten Antikörper gehört.

     

Interferon monotherapy for patients with chronic hepatitis C and normal serum aminotransferase levels at commencement of treatment

Background Approximately 30% of patients with chronic hepatitis C have normal serum alanine amino transferase (ALT) levels. While interferon (IFN) monotherapy is approved for patients with chronic hepatitis C infection, the effectiveness of such therapy for chronic hepatitis C patients with normal ALT levels at commencement of treatment remains poorly understood.Methods Ninety-four individuals (M/F, 54:40; median age, 46 years) with normal ALT levels (<50IU/l) at the commencement of treatment who were positive for both anti-hepatitis C virus (HCV) and serum HCV-RNA were studied. Among this group, 18 individuals (M/F, 9:9; median age, 50 years) had had persistently normal ALT levels for at least 3 months prior to treatment. All patients received their first course of IFN therapy in this study.Results Forty-three (45.7%) of 94 individuals had lost serum HCV-RNA at 6 months after cessation of therapy (complete response; CR). The proportion of patients with genotype 2a and HCV-RNA level over 1Meq/ml who showed CR was significantly lower in those with normal ALT levels than in those with elevated ALT levels (23.8% vs 55.6%; P = 0.0189). Two patients who had persistently normal ALT levels and HCV-RNA level over 1Meq/ml were nonresponders (NR) and had ALT flare-ups after IFN therapy. Patients with HCV-RNA levels of less than 1Meq/ml did not show differential responses based on ALT levels.Conclusions Our data suggest that IFN therapy is effective for patients with normal ALT levels and less than 1Meq/ml HCV-RNA. Thus, such patients should be considered for curative IFN therapy.     

Calcium-antagonists and islet function. IV. effect of D600

Summary D600 (2 to 20 M;-isopropyl- [(N-methyl-N-homoveratril)--aminopropyl]-3,4,5 -trimethoxyphenyl-acetonitril) caused a dose-related, rapid and reversible inhibition of glucose-induced insulin release. It also suppressed the insulinotropic action of a sulphonylurea but failed to affect the enhancing action of theophylline upon glucose-induced release. The inhibitory effect of D600 was enhanced at low extracellular Ca²⁺ concentration. D600 reduced both basal and glucose-stimulated⁴⁵calcium net uptake, whilst failing to affect the efflux of⁴⁵calcium from perifused islets. The recognition of glucose by the B-cell was also unaffected by D600 as judged by the effect of the sugar upon both 45 calcium efflux and net uptake in the isolated islets. These findings are compatible with the hypothesis that the primary mode of action of D600 is to inhibit Ca²⁺entry in the B-cell.(-isopropyl- [(N-methyl-N-homoveratril)--aminopropyl]-3, 4, 5-trimethoxyphenyl-acetonitril)     

[meso-1,2-Bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine]-dichloroplatinum(II), a new drug not only parenterally but also orally active in the therapy of breast and prostate cancer

The platinum complex [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)-ethylenediamine]dichloroplatinum(II), K, was tested for its antitumor activity on hormonesensitive tumor models under peroral administration. The resorption from the gastrointestinal tract was proved by determining the estrogenic effect of K in a dose/activity study using the immature-mouse uterine weight test. In comparison to the subcutaneous injection, a tenfold peroral dose was administered to achieve identical effects. By peroral treatment of the hormone-sensitive MXT(M3.2) mammary carcinoma of the mouse with K an almost complete inhibition of the tumor growth was obtained. This effect was superior to that of subcutaneously applied cisplatin and significantly better than that obtained by perorally administered ligand L at an equimolar dose, indicating that the antitumor effect is caused by the intact complex K and not by the liberated ligand L. The strong antitumor activity of perorally applied K was also demonstrated on the hormone-sensitive Noble Nb-R prostatic carcinoma of the rat. Histological examinations showed that the platinum complex K did not cause cisplatin-like kidney damage or irritations of gastric or intestinal mucosa when given perorally.Abbreviations DMBA dimethylbenz[a]anthracene - ER estrogen receptor - K complex - [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl (ethylenediamine]dichloroplatinum(II) - L ligand:meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine - LM 11 mixture (v/v) of polyethyleneglycol 400 and 1.8% NaCl - PEG polyethylene glycol     

Macrophages enhance binding of beta-VLDL and cholesterol ester accumulation in cultured aortic smooth muscle cells

Summary The effect of macrophages on the uptake of -very low-density lipoprotein (-VLDL) by smooth muscle cells (SMC) expressing different morphological phenotypes was examined in culture. The SMC were grown alone and in co-culture with macrophages for four days, then incubated with different concentrations of¹²⁵I--VLDL for 3 h at 4°C or with 75 ug/ml -VLDL for 24h at 37°C. The binding of -VLDL to SMC at 4°C was enhanced in the presence of macrophages irrespective of the phenotype expressed by SMC. This occurred through modification of the lipoprotein, since binding of re-isolated macrophage-conditioned -VLDL to SMC was 12.5 times that of fresh -VLDL. This modified form of -VLDL competed with fresh -VLDL for binding to SMC. Binding was inhibited in the presence of probucol, suggesting that an oxidative mechanism may be involved.The presence of macrophages also enhanced the accumulation of -VLDL-derived cholesterol in SMC. While most of this is a consequence of the enhanced binding, macrophages may also act directly on SMC to increase cholesterol accumulation, since the activity of acid cholesterol ester hydrolase and neutral cholesterol ester hydrolase in SMC was reduced in the presence of macrophages.     

Tannin inhibition of protein kinase C in airway epithelium

Tannin, a polydisperse polyphenol extracted from cotton bracts (CBE), has been implicated in the pathogenesis of byssinosis, a lung disease of mill workers. CBE tannin inhibits chloride secretion in airway epithelial cells by means of an unknown mechanism(s). Activation of protein kinase C (PKC) by PMA (phorbol 12-myristate 13-acetate) in airway cells increases chloride secretion. The effect of tannin on this PKC pathway was examined, using canine tracheal epithelium mounted in Ussing chambers. PMA addition (10 nM) to the mucosal bath resulted in a 0.36 ± 0.07 Eq/cm² · h (mean ± SEM, n = 20) increase in short-circuit current (I_sc) and a 0.38 ± 0.17 Eq/cm² · h increase in net chloride secretion (J_net). The inactive 4-phorbol had no effect. Tannin addition to the mucosal bath produced a dose-dependent decrease in I_sc and J_net. In tissues pretreated with 2–50 g/ml tannin, and subsequently stimulated with PMA, tannin inhibited PMA stimulation of chloride secretion beginning at a tannin concentration of 10 g/ml (0.09 ± 0.05 Eq/cm² · h [n = 10] increase in I_sc and 0.08 ± 0.03 Eq/cm² · h increase in J_net with PMA after tannin pretreatment). At 50 g/ml tannin, the stimulatory effect of PMA was completely abolished. The known PKC inhibitor, H-7 (20 M), inhibited PMA stimulation, while chelerythrine (2 M) had not effect on PMA-stimulated I_sc and J_net, and calphostin C was toxic to the airway epithelium. In membrane fragments, 2.5 g/ml tannin inhibited the rate of histone III phosphorylation by PMA from 32.1 ± 4.4 nmol/mg protein per min to 20.1 ± 2.7 nmol/mg protein per min (n = 7). In bovine airway cells, tannin pretreatment (2.5 g/ml) decreased the cytosolic activity of PKC but had no effect on PKC translocation to the membrane. We conclude that tannin inhibits chloride secretion in airway epithelial cells in part by inhibiting PKC.Offprint requests to: Michelle M. Cloutier     

Induction of an atypical interferon by bacteroides fragilis and escherichia coli in experimental infections and in leukocyte cultures

Summary Previous reports have shown thatBacteroides fragilis may enhance the pathogenicity of coinfecting enterobacteriaceae by interfering with the host's immune response. With the present study, we have investigated the possible role of interferons (IFN) in mediating these effects. Mice injected withB. fragilis developed moderate serum levels of IFN that appeared just prior to alterations of the animals' immunity described earlier. The IFN was neutralized by treatment with anti-IFN-alpha/beta-antibodies or hydrochloric acid; hence it displayed the same atypical characteristics as IFN found in patients with immuno-compromising diseases such as AIDS, systemic lupus erythematosus or rheumatoid arthritis.Escherichia coli displayed the same induction patterns asB. fragilis, while gram-positive bacteria induced regular IFN alpha/beta and gamma. Spleen cells, peritoneal macrophages, or liver leukocytes taken fromB. fragilis orE. coli-injected animals 6 h post infection were refractory to IFN induction byE. coli lipopolysaccharidein vitro; cells from mice infected with gram-positive organisms showed normal or enhanced responsiveness.

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Induktion eines atypischen Interferon durch Bacteroides fragilis und Escherichia coli in experimentellen Infektionen und in Leukozytenkulturen

Zusammenfassung Eine Reihe von Untersuchungen hat gezeigt, daßBacteroides fragilis in der Lage ist, die Wirtsabwehr zu beeinträchtigen und dadurch Koinfektionen mit Enterobacteriaceae zu begünstigen. Wir untersuchten die mögliche Rolle der Interferoninduktion in diesem Zusammenhang. Es zeigte sich, daß in experimentell mitB. fragilis infizierten Mäusen nachweisbare Interferonserumspiegel zeitlich unmittelbar vor bereits beschriebenen Veränderungen der Immunitätslage auftraten. Das Interferon (IFN) wurde durch Anti-IFN-Alpha/Beta-Antikörper oder durch Salzsäurebehandlung neutralisiert; es wies damit atypische Eigenschaften auf, die bereits für IFN von Patienten mit immunsupprimierenden Erkrankungen wie AIDS, Lupus erythematodes oder Rheumatoider Arthritis beschrieben wurden.B. fragilis undEscherichia coli zeigten ähnliche Induktionseigenschaften, während grampositive Bakterien normale IFN-Alpha/Beta und Gamma induzierten. Milzzellen, Peritonealmakrophagen oder Leberleukozyten, die von 6 Stunden zuvor mitB. fragilis oderE. coli infizierten Mäusen gewonnen wurden, waren hinsichtlich der IFN-Induktion mitE. coli-Lipopolysaccharidin vitro refraktär, während Zellen von mit grampositiven Bakterien infizierten Tierenin vitro normale oder vermehrte IFN-Produktion zeigten.

     

Comparison of dose-dependent enhancing effects of γ-ray irradiation on urethan-induced lung tumorigenesis in athymic nude (nu/nu) mice and euthymic (nu/+) littermates

The role of immunological surveillance in carcinogenesis is still controversial. In our previous experiments, urethan-induced lung tumorigenesis in athymic (nu/nu) mice and euthymic (nu/+) littermates was examined, and it was concluded that immunosurveillance mediated by T cells could not be demonstrated. However, the reported enhancement of development of various tumors following ionizing radiation might be achieved through modulating the host immunological conditions. In the present experiment,nu/nu and littermatenu/+ mice were treated with 1–4 Gy -rays alone at 6 weeks of age or treated with urethan at 0.5 mg/g body weight when aged 14 days followed by 1–4 Gy -rays 4 weeks later. Lung tumors were assessed at 6.5 months of age. Ionizing radiation itself caused a very low incidence of these lesions. On the other hand, multiplicities and incidences of lung tumors after urethan treatment at 0.5 mg/g body weight were similar between the two phenotypically different groups of mice (1.66 and 1.84 tumors/mouse, 73% and 80% incidences, fornu/nu andnu/+ cases respectively). This urethan-induced lung tumorigenesis was significantly enhanced by -rays in bothnu/nu andnu/+ mice, and the magnitude of tumor enhancement was somewhat higher innu/+ mice than innu/nu mice, especially with a 2-Gy dose. In conclusion, it may be said that lung tumorigenicity of -ray irradiation itself and the enhancing effect of radiation on urethan-induced tumorigenesis are scarcely influenced by immunosurveillance mechanisms mediated by T cells