Adult “idiopathic” extrahepatic venous thrombosis

The etiology of extrahepatic venous obstruction (EHVO) is unknown in 50% of cases. Recently the presence of a latent myeloproliferative disorder has been reported in adults with idiopathic EHVO. We evaluated the course of these patients to establish if any putative latent myeloproliferative disorder influenced the clinical course compared to those with a known cause. Among 132 EHVO patients, 78 (59%) had a known etiology, 7 (5%) with an overt myeloproliferative disorder. The idiopathic group had 54 patients; 24 (13 men, 11 women) were diagnosed after 15 years of age, (median 38 years, range 17–70) with a median follow up of 96 months (19–372). Only 2 (8%) developed an overt myeloproliferative disorder. These 24 had a similar pattern of bleeding and onset of ascites as those with known cause. In EHVO failure to diagnose a latent myeloproliferative disorder does not influence the course of variceal bleeding, and thus has little prognostic significance.Supported by R Farini Foundation for Gastroenterology Research.     

Detection of clonality by polymerase chain reaction in childhood B-lineage acute lymphoblastic leukemia

Summary DNA-based PCR with various sets of primers for TCR /, and Ig heavy chain (IgH) genes were used to study clonality in childhood B-lineage acute lymphoblastic leukemia. Amplification of the IgH CDR-III was observed in 75 of 120 analyzed cases (62.5%). From all analyzed groups, the IgH gene rearrangement was most often observed in pre-B ALL (85.7%) and was rather rare in null-ALL (34.5%). TCR delta gene rearrangement was the most common, and was observed in 77 patients (64.2%). The typical pattern of rearrangements was defined as anincomplete V2 to D3, V2 to D2, or D3 to D3 to D2 recombination product. Rearrangements of TCR gamma gene we observed in 61 cases (50.8%). TCR gamma gene rearrangements were detected predominantly in null-ALL and early B-ALL (55.2% and 60%, respectively) and were rather rare in other groups. Of all eight V segments of VI group, the most frequent gene usage concerns regions V2, V4, and V7. We have confirmed that IgH gene amplification, together with TCR gamma and delta gene amplification, provides a rapid, sensitive approach to assessing clonality in ALL almost in 100% of cases.This work was financed by KBN grants 4.0551.91.01 and 6.6346.92.03     

Uptake and metabolism of radiolabelled GM1-ganglioside in skin fibroblasts from controls and patients with GM1-gangliosidosis

Summary The uptake and metabolism of [3-³H-sphingosine]GM1-ganglioside was measured in cultured skin fibroblasts from controls and patients with infantile, juvenile and adult GM1-gangliosidosis. When dissolved in medium with phosphatidylserine, GM1-ganglioside was efficiently taken up by cultured skin fibroblasts and transferred into lysosomes. A linear increase in GM1-ganglioside endocytosis was shown with phosphatidylserine concentrations of up to 40m/ml. A pulse-chase study revealed that [³H]GM1-ganglioside was metabolized to GM2-ganglioside, GM3-ganglioside, ceramide dihexoside, ceramide monohexoside, ceramide and sphingosine. Sphingosine was recycled to sphingomyelin. In a 20-h pulse study, cell lines from patients with GM1-gangliosidosis of infantile, juvenile and adult types hydrolysed 2–5%, 20–44% and 54–58% of the total endocytosed GM1-ganglioside respectively. These values were lower than in control cells (64.17 ± 5.43% (n=10)). The hydrolysis rates of exogenous [³H]GM1-ganglioside in cultured fibroblasts from patients with various types of GM1-gangliosidosis closely reflected the clinical severity.Abbreviations GM1 Gal13GalNAc14(NeuAc23)Gal14Galc-1-ceramide - GM2 GalNAc14(NeuAc23)Gal14Glc-1-ceramide - GM3 NeuAc23Gal14Glc-1-ceramide - CDH Gal14Glc-1-ceramide     

Secretory component and lactoferrin in pure pancreatic juice in chronic pancreatitis

To evaluate pathophysiological roles of proteins in pancreatic secretion, immunoreactive lactoferrin (LF) and secretory component (SC) were measured in the first fraction of the pure pancreatic juice obtained endoscopically from 17 control, 21 suspected (SCP), 14 noncalcified (NCP), and 14 calcified chronic pancreatitis (CCP) subjects. The protein and amylase tended to decrease both in concentration and output from control to CCP. LF concentration was elevated in CCP (18.0±4.9/ml) when compared with controls (2.3±0.2g/ml), and LF output in NCP (12.3±3.8 g/min) was increased from controls (3.8±0.6 g/min). The combination of high LF concentration with low protein output was observed in 10/14 in CCP but 0/14 in NCP and can be a biochemical discriminator of CCP from NCP. SC concentrations were also elevated in NCP (8.5±2.0 g/ml) and CCP (5.6±1.6 g/ml) from controls (1.2±0.2 g/ml). SC outputs in SCP (9.8±3.1 g/min) and NCP (21.1±4.8 g/min) were increased from controls (1.7±0.3 g/min), but there was no further increase in CCP. Hypersecretion of LF and SC in chronic pancreatitis is different, especially in CCP, although the mechanisms for hypersecretion are unknown.This study was supported in part by a research grant for intractable pancreatic disease from the Ministry of Health and Welfare, Japan.     

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.     

Comparative and combined effects of transforming growth factors α and β, interleukin-1 and interferon-γ on rheumatoid synovial cell proliferation,glycolysis and prostaglandin E production

Summary Enhanced cell proliferation, glycolysis and prostaglandin E production are all characteristic features of rheumatoid synovial tissue. The interrelationships of these three cellular parameters have been examined using rheumatoid synovial fibroblasts and their responses to specific cytokines in vitro. Transforming growth factor (TGF) caused a more than threefold increase in synovial cell proliferation whilst transforming growth factor (TGF), interleukin-1 (IL-1) and interferon- (IFN-) produced only marginal changes. The combined addition of IL-1 with TGF resulted in an enhanced proliferative response comparable with that produced by TGF. Glycolysis, estimated by glucose utilisation and measurements of the glycolytic regulatory metabolite fructose 2,6-bisphosphate was significantly stimulated by TGF, IL-1 and IFN-, but less so by TGF. Prostaglandin E production was significantly increased by IL-1 to an extent much greater than that produced by TGF or TGF, although the combined addition of IL-1 with either TGF or resulted in a synergistic increase in PGE production, a response partly diminished by the addition of IFN-. These findings suggest that the extent to which a cytokine stimulates glycolysis is not consistently related to its mitogenicity, and that cytokine combinations which stimulate high levels of PGE production (a growth inhibitor) will not necessarily be associated with a reduced rate of cellular proliferation in cultured, adherent, rheumatoid synovial fibroblasts.     

Differential interleukin-1 receptor antagonism on pancreatic beta and alpha cells. Studies in rodent and human islets and in normal rats

Summary The monokines interleukin-1 and - have been implicated as effector molecules in the immune-mediated pancreatic beta-cell destruction leading to insulin-dependent diabetes mellitus. Here we investigated the effects of interleukin-1 receptor antagonism on insulin and glucagon release of rat, mouse and human islets exposed to recombinant human interleukin-1, and on interleukin-1 induced changes in blood glucose, serum insulin and serum glucagon levels in Wistar Kyoto rats. The interleukin-1 receptor antagonist reduced the co-mitogenic effect of interleukin-1 on mouse and rat thymocytes with a 50% inhibitory concentration of 10- and 100-fold molar excess, respectively. Complete inhibition was obtained with a 100–1,000-fold molar excess. However, at a 100-fold molar excess the interleukin-1 receptor antagonist did not antagonise the potentiating effect of interleukin-1on rat islet insulin accumulation during 3 and 6 h of exposure or of interleukin-1-induced inhibition of insulin release after 24 h. In contrast, interleukin-1-stimulated islet glucagon release was completely antagonised by a 100-fold molar excess of interleukin-1 receptor antagonist. A 10,000-fold molar excess of interleukin-1 receptor antagonist was needed to antagonise interleukin-1 stimulatory and inhibitory effects on rat beta-cell function in vitro. A 100-fold excess of interleukin-1 receptor antagonist could not counteract interleukin-1 effects on mouse and human beta cells, excluding species difference in the efficacy of the human interleukin-1 receptor antagonist. An anti-mouse interleukin-1 receptor type I antibody completely abolished interleukin-1 effects on isolated mouse islets. A 10–100-fold molar excess of interleukin-1 receptor antagonist antagonised interleukin-1-induced fever, hypercorticosteronaemia and hyperglucagonaemia, but not interleukin-1-induced reduction in insulin/glucose ratio in normal rats. In conclusion, our results suggest that antagonism of interleukin-1 effects on beta cells requires higher concentrations of interleukin-1 receptor antagonist than those necessary to block interleukin-1 action on islet alpha cells and other interleukin-1 targets in vitro and in vivo. This may contribute to the understanding of the specificity of the immunological beta-cell destruction leading to insulin-dependent diabetes.     

Follow-up of “non-diabetic” relatives of diabetics by retesting oral glucose tolerance after 5 years

Summary Of 743 first degree relatives of diabetics in whom oral glucose tolerance tests had been performed in 1967 488 were re-tested in 1972. Among the original normals (n = 353) 17.6% had developed a subclinical and 1.3% an overt diabetes within 5 years. The original subclinical diabetics (n = 118) showed a remission to normal in 35.6% and a progression to overt diabetes in 13.6%. 3 out of the 17 formerly overt diabetics were found to be normal after 5 years and 3 were subclinical diabetics. Thus the performance of an oral glucose tolerance test is of limited prognostic value in the individual case. In both studies a higher prevalence of abnormal test results occurred in the older age groups and in overweight subjects. Remission or deterioration did not depend, however, on age or on weight changes. The frequency of abnormal tests was higher in males than in females, but the tendency towards the development of diabetes was more pronounced in females, in accordance with a previous observation of a higher age dependance of glucose tolerance in females.     

Differential expression of cell surface integrins on human mast cells and human basophils

Summary Integrins are multifunctional recognition molecules and are expressed on various hematopoietic cells. In the present study expression of integrins on the cell surface of human mast cells and human basophils was investigated by using monoclonal antibodies (mAbs) and indirect immunofluorescence. Human mast cells were obtained from lung (n = 5), uterus (n = 5) and skin (n = 4). Human blood basophils were obtained from normal donors (n = 2). In addition, HMC-1 cells (human mast cell line) and KU-812 cells (a basophil cell line) were analyzed. Primary mast cells were found to react with mAbs directed against the common chain of 1 integrins (CD 29), the chain of VLA-4 (CD49d) and VLA-5 (CD49e), the chain of 3 integrins (CD 61), and the chain of the vitronectin receptor (VNR) (CD 51). Mast cells were not recognized by mAbs to 2 integrins (CD 18, CD 11 a, CD 11b, CD 11c), the chain of VLA-2 (CD 49 b), and VLA-6 (CD 49 f). No differences in expression of integrins on human mast cells obtained from different organs were found. HMC-1 cells and primary mast cells expressed an almost identical pattern of integrins. Human basophils and KU-812 cells were found to react with mAbs directed against 1-integrins (CD 29, CD 49 b, CD 49 d, CD 49 e) and 2-integrins (CD 18, CD 11 a, CD 11 b, CD 11 c). Together, mast cells and blood basophils express a unique pattern of integrins. These cell surface structures may be involved in the distribution of basophils and tissue mast cells and their accumulation and function in inflammed tissues.Supported by theFonds zur Förderung der Wissenschaftlichen Forschung in Österreich, grant no. P-7891     

Primärer Formwandel der Thrombozyten in vitro

Zusammenfassung Bei der Untersuchung mit dem Interferenz-Kontrast-Mikroskop zeigen die Thrombozyten nach der Blutentnahme im Zitrat-Blut, -Plasma, Heparin- und EDTA-Blut innerhalb von 30–60 charakteristische, quantifizierbare FormverÄnderungen: Quellung, Bildung von Pseudopodien, kleinsten Vesikeln und Unebenheiten an der PlÄttchenoberflÄche. Dieser Formwandel wird durch niedrige Inkubationstemperaturen (4 C, 10 C) gegenüber Zimmer temperatur beschleunigt; bei 37 C lÄuft er verzögert ab. Durch mechanische Alteration bei der Blutentnahme ist eine überproportionale Zunahme von a priori formverÄnderten Thrombozyten im sofort-fixierten Venenblut induzierbar. In vitro ist der Formwandel teilweise, in vivo vollstÄndig oder fast vollstÄndig reversibel. Einige bekannte Aggregationshemmer führen in vitro und z. T. auch nach oraler und intravenöser Applikation zu einer mehr oder minder ausgeprÄgten Hemmung (Bencyclan, SH 869 ASS > D-Propranolol) des Formwandels nach der Blutentnahme. Bencyclan, SH 869 und D-Propranolol bewirken dabei in vitro eine charakteristische Änderung der PlÄttchenform mit Bildung von KugelplÄttchen. Diespontane, primÄre FormverÄnderung der Thrombozyten nach der Blutentnahme ist wahrscheinlich nicht identisch mit der ADP-induzierten (sekundÄren), shape change. Die FormverÄnderung der PlÄttchen beeinflu\t wahrscheinlich das Ergebnis verschiedener Thrombozytenfunktions-und Aggregationsteste. Die Formwandelkinetik von klinisch Gesunden und Hodgkin-Kranken unterscheidet sich signifikant. Es ist möglich, da\ die beschriebene Methode in der Zukunft klinische Bedeutung gewinnt.     

Serum cytokines in patients with rheumatoid arthritis

Serum cytokines such as interleukin 1 (IL-1), interferon (IFN-), and tumor necrosis factor (TNF) were measured in 40 patients with rheumatoid arthritis (RA). In the 40 patients studied, serum IL-1 was detected in 5 patients, IFN- in 10 patients, and TNF in 20 patients. The IL-1-positive group showed increased values of activity indices compared to the IL-1-negative group. Values of serum IFN- correlated well with the number of peripheral blood lymphocytes and CD3⁺ cells and with the percentage of CD3⁺ CD26⁺ cells. Values of serum TNF correlated positively with the number of peripheral blood monocytes and the percentage of CD3⁺ HLA-DR⁺ and CD3⁺ CD25⁺ cells. These results indicated that serum IL-1 in RA patients reflects the activity of RA, while the serum IFN- and TNF in RA patients may be related to circulating activated lymphocytes and monocytes, respectively.     

Plasma and intracellular levels of lactate dehydrogenase,phosphohexose isomerase and lysozyme activity in acute leukemia

Summary Plasma and intracellular levels of lactate dehydrogenase (LDH), phosphohexose isomerase (PHI) and lysozyme activities were investigated in 20 patients with acute myelocytic leukemia (AML), 18 patients with acute lymphatic leukemia (ALL) and 10 patients with chronic myelocytic leukemia in blast transformation (CML/BT). Though the plasma levels of LDH and PHI in all patients with acute leukemia were elevated as compared to control persons there was no distinctive pattern which could be of use in the classification of acute leukemia. On the other hand the intracellular levels of these enzymes could be of value in classifying acute leukemia. The leukemic lymphoblasts were characterized by low levels of PHI and lysozyme as compared to leukemic myeloblasts or to normal lymphocytes (p<0.01). The LDH/PHI ratio is also significantly higher in leukemic lymphoblasts than in leukemic myeloblasts or in normal lymphocytes (p always <0.01). These characteristics might also be made use of in identifying the blasts of CML/BT als lymphoid or myeloid in corresponding cases.     

Presence of Two Signaling TGF-β Receptors in Human Pancreatic Cancer Correlates with Advanced Tumor Stage

Transforming growth factor- (TGF-)signal transduction is mediated via specific cellsurface signaling TGF- receptors, most notably thetype I ALK5 (TR-I_ALK5)and the type II(TR-II). We evaluated TR-I_ALK5 andTR-II expression in 41 human pancreatic cancertissue samples and correlated these findings withclinical data of the patients. Northern blot analysisindicated that, in comparison with the normal pancreas,pancreatic adenocarcinomas exhibited 8.0-fold and4.5-fold increases (P < 0.01), respectively, in mRNAlevels encoding TR-I_ALK5 andTR-II. In situ hybridization showed that both TR-I_ALK5 mRNAwere highly expressed in the majority of pancreaticcancer cells. Immunohistochemical analysis ofTR-I_ALK5 and TR-II revealedpositive immunostaining in 73% and 56% of the tumors, respectively. Both receptorswere concomitantly present in 54% of the pancreaticcancer samples. The presence ofTR-I_ALK5 or TR-II and theconcomitant presence of TR-I_ALK5 and TR-II in the cancer cells was associatedwith advanced tumor stage (P < 0.01). These findingsshow that in many human pancreatic cancers, increasedlevels of the two signaling TRs are present. The presence of the signaling TRs inadvanced tumor stages indicates a role in diseaseprogression.     

Serum β2-microglobulin,sialic acid,and C-reactive protein in systemic lupus erythematosus

Summary Serum ₂-microglobulin (₂m), sialic acid and C-reactive protein (CRP) were studied in 58 patients with systemic lupus erythematosus (SLE) on 186 occasions. Serum ₂m was significantly higher in SLE patients than in control subjects. Increased serum ₂m levels were seen in 68% of the patients with only extrarenal manifestations of SLE, in 75% of the patients with renal manifestations but normal glomerular filtration rate, and in 100% of the patients with renal failure. Serum ₂m levels in 12 SLE patients with associated Sjögren's syndrome were similar to those in patients without that syndrome. Serum sialic acid was also significantly increased in the SLE patients. Sixty-one (33%) of the 186 sera were positive for CRP (5 mg/l). The CRP elevation was not accompanied by recognized intercurrent infection or other superimposed cause of tissue injury and inflammation in 37 instances (61%). Under such conditions CRP was only moderately increased.     

Types of Adrenoreceptors Mediating Responses of Rabbit Gastric Muscularis Mucosae

This study investigated adrenoreceptor-mediated responses of muscularis mucosae from the fundic and antral ends of the rabbit gastric corpus. Norepinephrine-induced fundic muscularis mucosae contractions were enhanced by propranolol and converted to relaxations by phentolamine. Methoxamine, but not clonidine, elicited large fundic contractions. Fundic muscle responded to low isoproterenol concentrations with atenolol- and butoxamine-resistant relaxations, and to high concentrations with atenolol-sensitive contractions. Norepinephrine evoked propranolol-resistant relaxations of antral muscularis mucosae that were enhanced by phentolamine. Methoxamine and clonidine elicited small antral contractions. Lower concentrations of isoproterenol caused atenolol-resistant antral relaxations that were enhanced by butoxamine; higher concentrations produced weak excitation. Fundic and antral relaxations to isoproterenol were abolished by cyanopindolol. Fundic muscularis mucosae possesses excitatory ₁-, ₁- and inhibitory ₃-adrenoreceptors. Excitatory ₂- and inhibitory ₃-adrenoreceptors predominate in the antral region. The heterogeneous adrenoreceptor-mediated responses of the gastric muscularis mucosae suggest that adrenergic modulation of its motor activity is unlikely to be linked to acid secretion.     

Pharmacological evidence for beta3 adrenoceptors in the control of rat gastric acid secretion

The effect of the ₃-adrenoceptor agonist BRL37344 on gastric acid secretion evoked by different secretory stimuli was investigated in anaesthetized rats with lumen-perfused stomachs in comparison with the ₂-adrenoceptor agonist clenbuterol. Intravenous injections of BRL37344 (1–10 mol/kg) and clenbuterol (0.01–1 mol/kg) dose-dependently reduced 2-deoxy-D-glucose-induced acid secretion, with BRL37344 about forty times less potent than clenbuterol. BRL37344 (0.1–3 mol/kg) inhibited pentagastrin-induced acid output, whereas clenbuterol was effective only at high doses (10–100 mol/kg). The inhibitory effect of BRL37344 on pentagastrin-induced acid secretion was not modified by the nonselective –adrenoceptor antagonist propranolol, but it was prevented by bupranolol, a ₃-adrenoceptor antagonist. Furthermore, neither BRL37344 (10 mol/kg) nor clenbuterol (100 mol/kg) modified the acid secretion induced by histamine. These data suggest that ₃ adrenoceptors have an inhibitory role in the control of rat gastric acid secretion induced by indirect stimuli.     

17β-Estradiol Attenuates Quinolinic Acid Insult in the Rat Hippocampus

A number of studies have shown that 17-estradiol has neuroprotective properties. In this study the neuroprotective effect of 17-estradiol against quinolinic-acid-induced neuronal damage was investigated. Ovariectomized rats were separated into three groups of five animals each. Rats received daily subcutaneous injections of either olive oil or 17-estradiol in olive oil for 7 days prior to and following a single intrahippocampal injection of 1 mol quinolinic acid in 2 L phosphate-buffered saline. The brains were removed and the hippocampi either sectioned and stained for microscopic examination or used in glutamate receptor saturation binding studies. Glutamate receptor displacement binding studies were also performed using concentrations of 0.05 nM–5 M 17-estradiol or quinolinic acid. The results show that 17-estradiol protects hippocampal neurons from quinolinic-acid-induced neurodegeneration by competing with quinolinic acid to bind to the N-methyl-D-aspartate (NMDA) receptor. This would result in a decrease in intracellular free-calcium influx and resultant neuronal swelling.     

A Three-dimensional Analysis of Blood Vessels in Bronchioloalveolar Carcinoma

The three-dimensional architecture of blood vessels within lung adenocarcinomas has not been well studied. In 19 cases with bronchioloalveolar carcinoma with central fibrosis, we three-dimensionally examined blood vessel architecture in 150 m thick sections stained with elastin staining and anti-CD34 antibody. We examined four regions: normal alveoli and three regions within the tumor including an area adjacent to the normal alveoli (external area), an area in which tumor cells were replacing epithelial cells (replacement area), and a central fibrotic area (fibrotic area). Elastin staining showed that elastic fibers formed the framework of the alveoli, and the alveolar structure shrank more strongly to the center of the tumor due to folding of alveolar walls invaded by adenocarcinoma cells. We also measured three vessel parameters in these four regions. The vessel diameters were 4.08±1.10 m, 3.95±1.02 m, 5.04±1.56 m, and 6.11±2.23 m, the circumferences of those vessels seen as complete circles were 43.11±12.78 m, 43.71±12.87 m, 95.21±39.32 m, and 126.77±54.65 m; the lengths between vessel bifurcations were 13.28±3.08 m, 13.47±4.58 m, 24.91±9.66 m, and 41.82±28.08 m in the normal alveoli, and the external, replacement, and fibrotic areas, respectively. Blood vessel architecture changed such that the vessels became larger and coarser towards the center of the tumor. Our three-dimensional analysis suggests continuous remodeling of alveolar capillaries rather than angiogenesis within bronchioloalveolar carcinoma.     

Desensitization pattern of cardiac β-adrenoceptor subtypes by prolonged in vivo infusion of pindolol and celiprolol in rats

Summary The regulatory effects of pindolol and celiprolol on cardiac -adrenoceptor density were studied in vivo in order to assess the subtype selectivity of their partial agonistic activity (PAA). The substances were continuously administered to rats for 1 week by means of implanted osmotic minipumps. The density of -adrenoceptor subtypes were estimated from ICYP saturation binding experiments performed on cardiac ventricular plasma membranes in the presence of a highly selective antagonist (CGP 20172 A or ICI 118,551). Both antagonists were employed at concentrations as high as to block one subtype only without affecting the complementary subtype. For control purposes, rats were also treated with isoprenaline (0.4 mg/kg/h) and propranolol (0.15 mg/kg/h), or vehicle. Pindolol (0.036 mg/kg/h) and celiprolol (0.36 mg/kg/h) reduced the density of ventricular ₂-adrenoceptors by 46% and 23%, respectively, which — in the case of pindolol — was significant when compared to the non-treated controls. Both compounds, however, produced a small, but distinct increase in the number of ₁-adrenoceptors by approximately 26%. This finding is in contrast to the propranolol-induced upregulation of both ₁- and ₂-adrenoceptors by approximately 80%. Since supramaximal doses of each drug were administered, a significant smaller increase of ₁-adrenoceptors by pindolol and celiprolol —as compared to the increase produced by propranolol — can be interpreted as evidence for a PAA of pindolol and celiprolol on ₁-adrenoceptors as well. Isoprenaline as a full agonist caused a marked loss of of both -adrenoceptor subtypes. Although it exhibits equal affinity at both subtypes the decrease amounted to 80% of the ₂- but only to 54% of the ₁-adrenoceptors density. This indicates that the down-regulation of cardiac -adrenoceptors in general seems to be more pronounced at the ₂-than at the ₁-adrenoceptors population. We conclude that the subtype desensitization pattern of agents with intrinsic activity precludes the determination of subtype-selectivity, since ₁- and ₂-adrenoceptors appear to differ in their sensitivity presumably as a result of subtype specific baseline desensitization produced by endogenous catecholamines.     

Heat shock protein induction in rat pancreatic islets by recombinant human interleukin 1β

Summary Interleukin 1, potentiated by tumour necrosis factor , is cytotoxic to pancreatic Beta cells in vitro. We have hypothesized that interleukin 1 induces oxygen free radicals in Beta cells. Since cytotoxicity induced by free radicals and by heat may activate the same cellular repair mechanism (the heat shock response), the aim of this study was to investigate the pattern of protein synthesis in isolated islets after exposure to interleukin 1 (150 pg/ml, 24 h), tumour necrosis factor (50 ng/ml, 24 h), heat shock (43°C, 30 min) and H₂O₂ (0.1 mmol/l, 20 min). By polyacrylamide gel electrophoresis, autoradiography, Western-blot analysis and partial peptide mapping of ³⁵S-methionine labelled islets, interleukin 1 was found to induce a 73 kilodalton protein belonging to the heat shock protein family heat shock protein 70, a heat shock protein 90, and haem oxygenase. A minor induction of heat shock protein 73 and haem oxygenase was seen after H₂O₂. Interleukin 1 did not induce heat shock proteins in rat thyroid cells, rat mesangial cells or in human monocytes. Tumour necrosis factor did not induce selective protein synthesis. Pre-exposure of islets to heat, tumour necrosis factor , or H₂O₂ did not prevent the impairment of glucose-stimulated insulin release seen after 24 h of interleukin 1 exposure. The data are compatible with free radical induction by interleukin 1. However, the heat shock response is not specific for oxidative injury, and previous studies have shown discrepant effects as to a protective effect of free radical scavengers against interleukin 1-mediated beta-cytotoxicity. Thus, a role for free radicals in this context is not definitely proven.