Modulation of hematopoietic colony formation of stem cells in peripheral blood by anti-TGF-β in patients with severe immunosuppression

Summary The influence of transforming growth factor- (TGF-) on hematopoiesis has been evaluated by adding blocking antibodies against TGF- to colony forming assays (CFU-c). When optimum concentrations of recombinant growth factors, granulocyte-macrophage colony stimulating factor (GM-CSF), and interleukin-3 (IL-3) were added to stem cells from the peripheral blood of healthy individuals and certain patients with tumors or HIV infection, the anti-TGF- capable of blocking 5 ng/ml of active TGF- had no significant influence on erythroid or myeloid colony formation. However, in certain immunosuppressed individuals, anti-TGF- resulted in a significant decrease of erythroid colony formation and slight suppression of myeloid colony formation. The significant inhibition of hematopoiesis by plasma of HIV patients could be due to the presence of active forms of TGF-. The results of the blocking experiments are consistent with the concept that TGF- in low concentrations is essential for erythropoiesis and myelopoiesis but that higher levels of TGF- primarily inhibit erythropoiesis in vitro. TGF- serves as a coordinating factor when efficient recruitment of granulocytes and monocytes is more essential than erythropoiesis and stem cell growth.Abbreviations BFU-E burst forming unit-erythroid - CFC colony forming cells - CFU-GEMM colony forming unit-granulocyte/erythroid/macrophage/megacaryocyte - CFU-GM colony forming unit-granulocyte/macrophage - EPO erythropoietin - GM-CSF granulocyte/macrophage-colony stimulating factor - HIV human immunodeficiency virus - IL-1 interleukin-1 - IL-3 interleukin-3 - IMDM Iscove's Modified Dulbecco's medium - PBS phosphate buffered saline - TGF- transforming growth factor- - TNF- tumor necrosis factor-     

The role ofγδ T cells in the normal and disordered immune system

Summary A small population of T cells does not express the conventional T cell receptor characterized by the and polypeptide chains (TCR) but instead, two polypeptides termed and (TCR). This alternative receptor is able to recognize antigen. It appears early in T cell ontogeny, but its role in the thymus prior to the availability of TCR remains unclear. In selected sites such as skin or gut TCR predominates in mice which might suggest a role of T cells in the first line of defense against infection, T cells secrete lymphokines and display cytotoxic activity. However, their activation requirements may differ from what is known for T cells since MHC-nonrestricted and also CD4 and CD8 negative T cells have been described. Preferential activation by mycobacterial antigens possibly indicates a special repertoire of the T cells. In various diseases slightly increased numbers of T cells were found, but these preliminary studies have not yet provided evidence for a major pathogenetic role of T cells.List of abbreviations C constant region (immunoglobulin or TCR gene segment) - CD4 cluster of differentiation 4 (mainly on helper cells) - CD8 cluster of differentiation 8 (mainly on cytotoxic cells) - D diversity region (immunoglobulin or TCR gene segment) - DNA desoxyribonucleic acid - IL2 interleukin 2 - J joining region (immunoglobulin or TCR gene segment) - kD kiloDalton - MHC major histocompatibility complex - NK natural killer (cells) - RA rheumatoid arthritis - TCR T cell receptor - V variable region (immunoglobulin or TCR gene segment)     

Regulated overproduction of α-amylase by transformation of the amylolytic yeast Schwanniomyces occidentalis

Summary High frequency transformation of a Schwanniomyces occidentalis mutant defective in the last step of tryptophan synthesis was achieved with plasmids containing the tryptophan synthetase gene (TRP5) of Saccharomyces cerevisiae and an autonomous replication sequence from S. occidentalis, which we called SwARS1. The SwARS1 fragment is also functional in S. cerevisiae. The average copy number of the plasmids in both yeast species was 5–10 per cell under selective conditions. S. occidentalis cells that were transformed with an autonomously replicating plasmid carrying the cloned -amylase gene from S. occidentalis secreted about five times more -amylase than cells without additional copies of the -amylase gene. Both the chromosomal copy and the plasmid-carried copies of the -amylase gene were repressed in the presence of glucose. This transformation system provides a possibility to improve starch degradation by S. occidentalis.     

Genetic characterization of an α-specific gene responsible for sexual agglutinability in Saccharomyces cerevisiae: mapping and gene dose effect

Summary A recessive ag1 mutation leads to specific defect in sexual agglutinability specifically in cells of the yeast Saccharomyces cerevisiae. The cryptopleurine resistance gene cry^R 1, closely linked to the mating type locus, was used to select / strains which emerged from / strains by mitotic nonreciprocal recombination, to genetically analyse ag1, since ag1 is expressed only in mating type. The ag1 gene was found to be linked to the centromere tightly, to met3 at 4.4 cM, and to ilv3 at 12 cM on chromosome X. Sexual agglutinability of cells was shown to be dependent on the dose of the AG1 gene, using / isogenic strains carrying AG1/AG1, AG1/ag1 or ag1/ag1. The sst2-1 mutation did not suppress the ag1 mutation. Based on these results, function of the AG1 gene is discussed.Abbreviations cM centimorgan - FDS first division segregation - NPD nonparental ditype - PD parental ditype - SDS second division segregation - TT tetratype     

ω-Grammotoxin blocks action-potential-induced Ca2+ influx and whole-cell Ca2+ current in rat dorsal-root ganglion neurons

Field-potential stimulation of rat dorsal-root ganglion (DRG) neurons evoked action-potential-mediated transient increases in intracellular free calcium concentration ([Ca²⁺]_i) as measured by indo-1-based microfluorimetry. Field-potential-evoked [Ca²⁺]_i transients were abolished by tetrodotoxin, and their dependence on stimulus intensity exhibited an abrupt threshold. -Conotoxin GVIA (-CgTx, 100 nM) inhibited action-potential-mediated Ca²⁺ influx by 79%, while nitrendipine (1 M) had little effect. -Grammotoxin SIA (-GsTx, 267 nM), a peptide toxin purified from the venom of the tarantula spider, Grammostola spatulata, blocked action-potential-mediated Ca²⁺ influx as effectively as did -CgTx, suggesting that -GsTx blocks N-type Ca²⁺ channels. In contrast to block by -CgTx, the block produced by -GsTx reversed upon washout of the peptide. -GsTx (270 nM) blocked 80%, and -CgTx (1 M) blocked 64%, of whole-cell Ca²⁺ current (I _Ca) elicited by step depolarization to 0 mV from a holding potential of –80 mV. -GsTx completely occluded inhibition of I _Ca by -CgTx. However, when applied after -CgTx, -GsTx produced an additional inhibition of 27%, indicating that -GsTx also blocked a non-N-type Ca²⁺ channel. BayK8644 (1 M) elicited an increase in I _Ca in the presence of maximally effective concentrations of -GsTx, suggesting that -GsTx does not block L-type channels. Thus, -GsTx displays a selectivity for Ca²⁺ channel subtypes which should prove useful for studying Ca²⁺ channels and Ca²⁺-channel-mediated processes.     

Trennung der intestinalen β-Galactosidasen beim lactose-toleranten Erwachsenen durch Ultrazentrifugation im Dichtegradienten

Zusammenfassung Die intestinalen-Galactosidasen von 4 lactose-toleranten, erwachsenen Mitteleuropäern wurden im Saugbiopsie-Gewebe nach Solubilisierung mit Triton X-100 in einem linearen Mannitol-Gradienten (5–20%) auf der Ultrazentrifuge bei 4°C und 44000 U/min getrennt. Bei 12stündiger Zentrifugation fanden sich 3 Fraktionen, von denen die beiden schneller sedimenticrenden Lactose spalten. Alle 3 Fraktionen hydrolysieren p-Nitrophenyl--Galactosid. Die 3 isolierten-Galactosidasen entsprechen wahrscheinlich der neutralen Bürstensaum-Lactase, der sauren lysosomalen Lactase und einer cytoplasmatischen Hetero--Galactosidase.     

Bicarbonate permeability of epithelial chloride channels

To investigate the relation of arachidonate metabolism to the induction of fever by interleukin-1, indomethacin was administered in either an intracerebro-ventricular (icv) or a subcutaneous (sc) route in conscious rabbits. Fever induced by icv administration of recombinant human interleukin-1 (rhIL-1) was depressed by either icv or sc pretreatment with indomethacin. Fever induced by intravenous (iv) administration of rhIL-1 was significantly inhibited, though initial small increase in colonic temperature still remained, and was completely depressed by combination of icv and sc pretreatment with indomethacin. Intracerebroventricularly administered recombinant rabbit IL-1 (rrIL-1) induced dose-dependent increases in colonic temperature, which was depressed by sc pretreatment with indomethacin. There is little species specificity between human and rabbit IL-1, in terms of the pyrogenic potency and the inhibitory effect of sc indomethacin on fever induced by icv IL-1. Further, fever caused by icv administration of sodium arachidonate was significantly depressed by sc pretreatment with indomethacin. These results show that the inhibitory effect of indomethacin, administered either icv or sc, on IL-1-induced fever is similar to that of IL-1-induced fever reported previously [11]. This suggests that the site of arachidonate metabolism significantly involved in the mechanism of fever induction by IL-1 is easily accessible to the brain from the blood.     

A mutation affecting sexual agglutinability in MATα locus of Saccharomyces cerevisiae

Summary A temperature-sensitive non-agglutinative mutant of Saccharomyces cerevisiae was isolated and characterized. The mutation, sag2, affected sexual agglutination, conjugation and production of -mating pheromone at a restrictive temperature, but not the response to -mating pheromone. Genetic analyses showed that the mutation was recessive and in the MAT locus. The sag2 mutation complemented with mat2 but not with mat1 These results suggest that sag2 is in the MAT1 gene and that at a restrictive temperature the mutation, sag2, inactivated the MAT1 product, a positive regulator of -mating functions. The sag2 mutation is like mat1-5 in its retention of response to -mating pheromone. However, at 25 °C, sag2 cells were competent to mate, whereas mat1-5 cells were not. Hence, sag2 is regarded as a new allele in the MAT1 gene, which we designate mat1-11.     

Phenotypic differences between induced and spontaneous 2μ-plasmid-free segregants of Saccharomyces cerevisiae

Summary The maximum specific growth rates (_max) of 2 -plasmid-free ([cir°]) segregants of three haploid and one diploid strain of Saccharomyces cerevisiae have been determined and compared with the _max of their 2 -plasmid-containing ([cir ⁺]) progenitors. Two classes of [cir°] strains have been examined: those induced by transformation with a 2 -based recombinant plasmid according to the method of Dobson et al. (1980) and those isolated as spontaneous [cir°] segregants from glucose-limited continuous cultures. The _max of the spontaneous [cir°] segregants was not found to differ significantly from that of their [cir ⁺] parents. In all cases, however, the induced [cir°] strains had a _max which was significantly less than that of their [cir ⁺] counterparts. This effect was particularly marked in the case of the diploid strain where a 34% reduction in _max was observed. The implications of these results are discussed in terms of the effect of the transformation process on host yeast cells.     

Kinetic and pharmacological properties of high- and low-threshold calcium channels in primary cultures of rat hippocampal neurons

The kinetic, permeability and pharmacological properties of Ca currents were investigated in primary cultures of rat hippocampal neurons. The low-voltage-activated (LVA) Ca current turned on positive to –60mV and fully inactivated in a voltage-dependent way. This current was depressed by nickel (Ni, 40 M) and amiloride (500 M) and was insensitive to -conotoxin (-CgTx) (4 M) and to the Ca agonist Bay K 8644 (5 M). The high-voltage-activated (HVA) Ca current turned on positive to –40 mV and inactivated slowly and incompletely. This current was much less sensitive than the LVA current to Ni and amiloride but more sensitive to cadmium. CgTx blocked only partially this current (about 50%) in an irreversible way. Bay K 8644 had a clear agonistic action almost exclusively on the -CgTx-resistant HVA current component. The present results suggest that the HVA channels, quite homogeneous for their kinetic properties and sensitivity to holding potentials, can be pharmacologically separated in two classes: (i) -CgTx-sensitive and Bay-K-8644-insensitive (-S/BK-I) and (ii) -CgTx-insensitive and Bay-K-8644-sensitive (-I/BK-S), the latter displaying a stronger Cadependent inactivation.     

Interferon-α activates cytotoxic function but inhibits interleukin-2-mediated proliferation and tumor necrosis factor-α secretion by immature human natural killer cells

Natural killer (NK) cells play an important role in host defense mechanisms against infection and neoplasia. Interferon- (IFN-) has been shown to activate NK cells and to augment their cytotoxic activity, albeit its role in the maturation pathway of NK cells has not been elucidated. The present study examined whether IFN- activates the immature NK subset (Free cells) to become cytotoxic and also ascertained whether IFN- uses the same pathway of activation as that mediated by interleukin-2 (IL-2). Incubation of sorted Free cells overnight with IFN- resulted in augmentation of their cytotoxic function against NK sensitive target cells. The enhanced cytotoxic activity was not accompanied by a new recruitment of NK-target binder cells but by an increase in the frequency of killer cells in the conjugate fraction. Activation of the Free subset by IFN- resulted in upregulation of CD69, CD11b, and CD2 surface expression and stimulated secretion of IFN-. Unlike IL-2, IFN- did not stimulate the Free cells to proliferate or secrete TNF- and activation of cytotoxicity and modulation of surface antigens by IFN- were independent of TNF-. The failure of IFN- to stimulate secretion and proliferation by Free cells appeared to be mediated by negative signals. This was corroborated in experiments demonstrating that when Free cells were cultured with both IFN- and IL-2, a significant inhibition was observed for both the IL-2 dependent secretion of TNF- and proliferation. These results demonstrate that IFN- serves as both an activator and a regulator of NK function. Further, activation of the immature Free NK cells by IL-2 and IFN- proceeds by TNF--dependent and independent pathways, respectively. The findings also support our contention that the mechanism of activation of the cytotoxic machinery of NK cells is not linked to the mechanism of activation of cytokine secretion and/or proliferation.Abbreviations used IFN interferon - IL interleukin - PBL peripheral blood leukocytes - PE phycoerythrin - PE-GAM PE-conjugated Fab2 goat anti-mouse IgG - NK natural killer - NRS normal rabbit serum - TNF tumor necrosis factor - FCS fetal calf serum - FITC fluorescein isothiocyanate - PBS phosphate-buffered saline - MACS magnetic cell sorting - ELISA enzyme-linked immunosorbent assay - BSA bovine serum albumin - PKC protein kinase C - mAb monoclonal antibody - PBMC peripheral blood mononuclear cells - BCLL B-chronic lymphocytic leukemia - E effector - T target     

Expression of the Escherichia coli β-glucuronidase gene in industrial and phytopathogenic filamentous fungi

Summary The plant pathogenic fungus Pseudocercosporella herpotrichoides has been successfully transformed using two positive selection systems, one based on the Escherichia coli hygromycin B phosphotransferase gene (hph) and the other on the Neurospora crassa -tubulin gene bml which encodes resistance to the methyl benzimidazole carbamate fungicides. Both selection systems gave a transformation frequency of 1–20 transformants g^–1 DNA. The vector DNA was integrated into the genome and the number and sites of integration varied among the transformants. The hph transformants were mitotically stable and the transformed gene was transmitted through spores. In contrast the bml transformants were less stable.     

Bile acids and their amidates inhibit 11β-hydroxysteroid dehydrogenase obtained from rat kidney

Recently it has ben demonstrated that interaction of corticosteroids with extraadrenal target cells can effectively be modulated by metabolic transformation of the steroid hormone. As far as 11-hydroxylated glucocorticoids are concerned 11-hydroxysteroid dehydrogenase (11-HSD) is the most important enzyme charged with target cell metabolism. Inhibition of 11-HSD function either by genetically transmitted deficiency or by exogenous enzyme inhibitors causes severe pathophysiological derangements, which result in a syndrome of apparent mineralocorticoid excess. In the present paper we have tested whether or not endogenous inhibitors of this enzyme system might exist. The effects of the main naturally occurring mono-, di-, and trihydroxylated bile acids in man on 11-HSD have been studied in in vitro experiments. Using rat renal microsomes it could be demonstrated that unconjugated bile acids of all three classes as well as the corresponding glycine and taurine amidates effectively inhibit oxidative as well as reductive activity of 11-HSD, with lithocholic acid and chenodeoxycholic acid being the most potent compounds. It is concluded that bile acids are potent endogenous inhibitors of 11-HSD and, therefore, could participate in abnormalities of cortisol metabolism observed in liver cirrhosis and extrahepatic biliary obstruction and, possibly, after ingestion of bile acids.Abbreviations CA cholic acid - CDCA chenodeoxycholic acid - DCA deoxycholic acid - GCA glycocholic acid - GCDCA glycochenodeoxycholic acid - GLCA glycolithocholic acid - 11-HSD 11-hydroxysteroid dehydrogenase (EC 1.1.1.146) - IC₅₀ molar concentration of bile acid at 50% inhibition of enzyme activity - LCA lithocholic acid - TDCA taurodeoxycholic acid - TLCA taurolithocholic acid - TUDCA tauroursodeoxycholic acid - UDCA ursodeoxycholic acid Supported by the Deutsche Forschungsgemeinschaft Hi 97/16 1-4. Parts of this study have been presented at the 21st meeting of the Gesellschaft für Nephrologie [23]     

Proteinase — Antiproteinase imbalance in meningitis: Determination of α 1 proteinase inhibitor (α 1PI), elastase — α-1PI complex,and elastase inhibition capacity in cerebrospinal fluid

Summary Mortality and long-term neurologic sequelae are still frequent complications of meningitis despite effective antibiotic treatment. This suggests that pathogen-independent inflammatory mechanisms may play an important role in the course of this illness.Neutrophil granulocytes form the primary immune defense in meningitis. Once activated, these cells release elastase into the cerebrospinal fluid (CSF). Elastase may induce tissue damage if local antiproteinase capacity is low as under normal conditions.To define the relevance of this mechanism we studied 22 patients with meningitis. Concentrations of elastase in complex with the main antiproteinase 1-proteinase inhibitor (elastase- 1PI), 1-proteinase inhibitor ( 1PI), and elastase inhibition capacity (EIC) were measured in CSF of 9 patients with bacterial meningitis (BM), aged 1 month-214 years; 13 patients with non-bacterial meningitis (NBM), aged 1 month–15 years; and 20 patients in whom meningitis was excluded after spinal tap (control group), aged 6 months–15 years. The concentration of elastase- 1PI in the BM group (median 552 g/l) was significantly higher than in either the NBM group (median 30 g/l,p<0.01) or the control group (median 30 g/l,p<0.01). Similarly, the 1PI-concentration in the BM group was significantly higher (median 113 mg/l) than either the NBM group (median 13.7 mg/l,p<0.025) or the control group (median 6.3 mg/l,p<0.001). The concentration of elastase- 1PI shows a significant correlation with the duration of the infectious symptoms before admission to the hospital (r=0.51,p<0.02), but not with the number of neutrophil granulocytesr=0.23, p=0.21).Free elastolytic capacity in CSF could be demonstrated in 4 patients: 1 with BM, 2 with NBM, and 1 with pertussis pneumonia and enzephalitis.The measured insufficiency of the proteinase-antiproteinase system may indicate high-risk patients in need of additional anti-inflammatory therapy, e.g., with corticosteroids, during the initial phase of meningitis.Abbreviations 1PI 1-proteinase inhibitor, 1-antitrypsin - elastase- 1PI complex elastase- 1-proteinase inhibitor complex - EIC elastase inhibition capacity - BM group: bacterial meningitis - NBM group: non-bacterial meningitis - CSF cerebrospinal fluid     

Isoenzymes of γ-glutamyl transpeptidase in liver diseases

Summary A new method for the separation of isoenzymes of-glutamyl-transpeptidase is described, using electrophoresis on acetate cellulose gel and a developing solution composed by-glutamyl-naphthylamide, and a colored diazonium compound.The method permits the separation of up to four different isoenzymes, which we called-GT₁,-GT₂,-GT₃,-GT₄, the first two showing an electrophoretic migration similar to that of ₁- and ₂-globulins and the other two to that of-globulins.The present technique has proved its usefulness in detecting isoenzymes in serum with values of total-glutamyl-transpeptidase higher than 80 U/L.The application of this method in 52 patients with different types of biliary obstruction and hepatocellular damage has shown that it provides new possibilities in differential diagnosis.     

Differential effects of prednisolone and indomethacin on zymosaninduced inflammation in a modified murine tissue-chamber model

A tissue-chamber model of inflammation in mice has been modified and used to investigate the kinetics of zymosan-induced inflammatory mediators such as tumour necrosis factor (TNF), interleukin-1 (IL-1) and prostaglandin E₂ (PGE₂). In addition, the influx of polymorphonuclear leukocytes (PMN) into the chamber fluid and the granuloma surrounding the chamber was measured by myeloperoxidase (MPO) activity using a new microtitre plate assay. TNF and IL-1 reached peak concentrations at 3 and 6 h respectively after zymosan injection. Intermediate high concentrations of IL-1 were observed until the end of the experiment at 72 h, but TNF concentrations decreased from 24 h to biologically insignificant values. In contrast, exudate PGE₂ and MPO activity increased up to 24 h after zymosan injection and remained high until 72 h. At 6h after zymosan challenge, oral pre-treatment with prednisolone (3 to 30mg/kg) dose-dependently reduced TNF, IL-1 and PGE₂ concentrations while indomethacin (0.3 to 3 mg/kg) significantly attenuated PGE₂, slightly enhanced TNF and had no effect on IL-1 concentrations in the exudate. Both drugs had similar potencies against exudate and tissue MPO activities. Prednisolone inhibited IL-1 at 72 h post-zymosan. Indomethacin was more potent than prednisolone against PGE₂ (ID₅₀ of <0.3 versus 0.6mg/kg). The data obtained confirm the usefulness and reliability of this model in evaluating the effects of anti-inflammatory agents on inflammatory mediators induced by zymosan.     

Overshoot in <Emphasis Type="Italic">V̇</Emphasis>O<Subscript>2</Subscript> following the onset of moderate-intensity cycle exercise in trained cyclists

We have previously observed that following the onset of moderate intensity cycle ergometry, the pulmonary O₂ uptake (O₂) in trained cyclists often does not increase towards its steady-state value with the typical mono-exponential characteristics; rather, there is a transient overshoot. The purpose of this study was to systematically examine this phenomenon by comparing the O₂responses to two moderate-intensity work rates and one high-intensity work rate in trained and untrained subjects. Following a ramp exercise test to the limit of tolerance for the determination of the gas exchange threshold (GET) and O_2peak, seven trained cyclists [mean (SD); O_2peak 66.6 (2.5) ml·kg^–1·min^–1] and eight sedentary subjects [O_2peak 42.9 (5.1) ml·kg^–1·min^–1] completed six step transitions from baseline cycling to work rates requiring 60% and 80% GET and three step transitions from baseline cycling to a work rate requiring 50% of the difference between GET and O_2peak (50%). O₂ was measured breath-by-breath and modelled using standard techniques. The sedentary subjects did not overshoot the steady-state O₂ at any intensity. At 60% GET, six of the seven cyclists overshot the steady-state O₂ [by an integral volume of 164 (44) ml between ~45 and 125 s]. At 80% GET, four of the seven cyclists overshot the steady-state O₂ [by an integral volume of 185 (92) ml between ~55 and 140 s]. None of the cyclists showed an overshoot at 50%. These results indicate that trained cyclists evidence an overshoot in O₂ before steady-state is reached in the transition to moderate-intensity exercise. The mechanism(s) responsible for this effect remains to be elucidated, as does whether the overshoot confers any functional or performance benefit to the trained cyclist.     

Diameter and flow velocity changes of feline small pulmonary vessels in response to sympathetic nerve stimulation

Using an X-ray television system, we measured directly changes in the internal diameter (ID), flow velocity, and volume flow of the small pulmonary vessels (100–500 m ID) in response to electrical sympathetic nerve stimulation (SNS) in anaesthetized cats before and after adrenergic receptor blockade. Flow velocity was obtained by measuring the distance that the leading edge of the contrast medium moved per 0.1 s in the small arteries. Volume flow was obtained from the product of flow velocity and cross-sectional area calculated from the ID of the small arteries. SNS was accolmplished with 10- to 15-V square-wave pulses of 2-ms duration at 20–30 Hz for 20-s periods. In response to SNS, arterial ID decreased significantly by 8–13% in the 200- to 500-m vessels but not in the 100- to 200-m vessels. In the veins, on the other hand, there was no significant ID decrease in any of the 100- to 500-m vessels. After -receptor blockade (phentolamine, 2 mg/kg i.V.), there were significant ID increases (4–9%) in the 100- to 500-m arteries in response to SNS, the maximum increases being in the 100- to 200-m arteries. After -blockade (propranolol, 2 mg/kg i.V.), the ID decrease due to SNS in the 200- to 500-m arteries was enhanced (24–27%) and, in addition, the 100- to 200-m arteries exhibited a significant ID decrease (18%). Combined and -blockade completely abolished the ID decrease due to SNS. In the veins, on the other hand, no ID change occurred even after - or -blockade. The results indicate that SNS selectively constricts 200- to 500-m arteries. The data suggests that SNS has -mediated vasoconstrictor and -mediated vasodilator effects on the 100- to 500-m arteries and that the ID response pattern to SNS depends chiefly on the balance between -mediated vasoconstriction and -mediated vasodilation. Associated with the ID decrease due to SNS, flow velocity was increased by 21%. However, SNS did not affect volume flow, because the increase in velocity was compensated by the reduction in the cross-sectional area (due to the decreased ID).     

Trennung der intestinalen β-Galactosidasen beim lactose-intoleranten Erwachsenen durch Ultrazentrifugation im Dichtegradienten

Zusammenfassung Bei 11 erwachsenen Versuchspersonen mit Lactose-Intoleranz konnten bei der Trennung der intestinalen-Galactosidasen im Dichtegradienten die neutrale Bürstensaum-Lactase und die saure lysosomale Lactase nachgewiesen werden. Im Vergleich zu lactose-toleranten Erwachsenen war die Bürstensaum-Lactase stark vermindert. Die Hetero--Galactosidase, die bei lactose-toleranten Erwachsenen als langsam sedimentierendes Enzym nachweisbar ist, fehlte bei allen 11 Versuchspersonen.Diese Arbeit wurde durch die Stiftung Volkswagenwerk und durch das Landesamt für Forschung Nordrhein-Westfalen unterstützt.     

Presence of two isoforms of Na,K-ATPase with different pharmacological and immunological properties in the rat kidney

Previous studies have demonstrated the presence of two populations of Na,K-ATPase with distinct kinetic, pharmacological and immunological characteristics along the rabbit nephron, indicating that the proximal segments of the nephron express exclusively the ₁ isoform of the catalytic subunit, whereas the collecting duct expresses an ₃-like isoform. Because pharmacological studies have shown the existence of two populations of Na,K-ATPase with different sensitivities to ouabain in the rat cortical collecting duct, which may result from the presence in the same nephron segment of the two isoforms demonstrated in the different segments of the rabbit nephron, the present study was undertaken to characterize the properties of Na,K-ATPase along the rat nephron. Results indicate that each segment of the rat nephron contains two subpopulations of Na,K-ATPase: a component highly sensitive to ouabain (IC₅₀ 5.10^–6 M) which is recognized by an anti- ₃ antibody and another moiety of lower affinity for ouabain (IC₅₀ 5.10^–4 M) which is recognized by an anti- ₁ antibody. Whether these two subpopulations correspond to different isoforms of the subunit of Na,K-ATPase ( ₁ and ₃-like) remains to be determined.