Lactic acidosis during metformin treatment in an elderly diabetic patient with impaired renal function

In recent years, lactic acidosis has been described in association with metformin therapy in diabetics. We report a fatal case in an elderly diabetic patient with impaired renal function and cardiac insufficiency. The patient presented with an elevated plasma metformin concentration and a concomitant digitoxin intoxication.

Lower breast cancer survival in mothers of children with a malignancy: a national study

As it is unclear if hereditary factors affect breast cancer survival, this was compared using fertility and cancer registry data, among all women so diagnosed during 1961–1999 in Sweden, having a child with childhood cancer (⩽20 years of age; n=254) and with that of other women (n=74 781). Those having a child with a childhood malignancy had a significantly worse survival than other women, relative risk (RR)=1.25, 95% CI 1.02–1.55, P<0.04, adjusted for age at diagnosis, year of diagnosis, parity and time since last pregnancy. Childhood sarcomas or acute myeloid leukaemia seemed to be most associated with a worse survival in the mother (RR=1.38 and 1.69, respectively). The lower survival of the mother was present for breast cancer diagnosed both before and after 50 years of age. The Li–Fraumeni syndrome and possibly other genetic disorders may lower breast cancer survival.

Isolation of transcriptionally active umbilical cord blood-derived basophils expressing Fc epsilon RI, HLA-DR and CD203c

BACKGROUND

Basophils are inflammatory cells associated with allergy and parasite infections. Investigation of their true biological function has long been hampered by the difficulty in obtaining sufficient amounts of pure basophils and by the lack of phenotypic markers. Moreover, it has been very difficult to clone and identify basophil-specific granule proteins, partially because of an almost complete lack of mRNA in mature circulating basophils.

METHODS

To obtain transcriptionally active immature basophils, umbilical cord blood cells were cultured in the presence of interleukin (IL)-3. The cells were analysed by flow cytometry and by histological staining.

RESULTS

The continuous presence of IL-3 in cord blood cultures resulted in the expansion of basophil precursors co-expressing FcepsilonRI and the recently described mast cell/basophil marker, 97A6 (CD203c). Several nonbasophil markers (i.e. CD3, CD14, CD15, CD16, CD19 and CD21) were absent on the cultured basophils. However, we show that in early cultures, almost 60% of the CD203c+ cells co-express human leukocyte antigen (HLA)-DR, a marker that is absent on mature circulating basophils. The presence of HLA-DR on basophil precursors may explain the low recovery (24+/-5.2%) obtained after isolation of cultured basophils, when using a conventional basophil isolation kit that removes HLA-DR+ cells. A novel purification method was developed, including a two-step cocktail of antibodies against selected markers, which resulted in both high purity (95+/-0.5%) and recovery (59+/-1.5%) of cultured basophils.

CONCLUSIONS

We here establish cord blood cultures as a source from which transcriptionally active basophil precursors can be isolated in reasonable quantities for thorough biochemical characterization.

IgG Immune Complex-Binding in Macrophages From Arthritis-Susceptible and Arthritis-Resistant Mice Following Collagen Type II Immunization

Occupancy of Fc gamma receptors (FcgammaR) by immune complexes (IC) induces secretion of various inflammatory mediators and cytokines. Therefore, knowledge of the FcR function is fundamental for understanding inflammatory processes. Here, we report an alteration in the FcR function in collagen-induced arthritis (CIA). The FcgammaR-binding activity of peritoneal macrophages from arthritis-susceptible DBA/1 mice following collagen type II (CII)/CFA immunization was assessed by Fc rosetting of SRBC opsonized with different IgG subclasses. A progressive reduction of IgG1 IC-binding was observed after immunization, and by the time of arthritis onset, the IgG1 IC-binding was abolished. Binding of IgG2a or IgG2b IC, however, was not affected. The blocked IgG1 IC-binding was reversed by a prior mild acid wash of the CIA macrophages, indicating receptor occupancy as the cause of the blocked binding. The impaired IgG1 IC-binding was associated with arthritis development, as macrophages from CII/CFA-immunized, arthritis-resistant SWR mice or DBA/1 mice, immunized with CFA alone, did not show this effect. Normal DBA/1 macrophages, blocked with a monoclonal antibody to FcgammaRIIB/FcgammaRIII, and macrophages from FcgammaRIII-deficient mice did not bind IgG1 IC, indicating FcgammaRIII as responsible for IgG1 IC-binding. Our data suggest that an increased degree of saturation of FcgammaRIII precedes the development of CIA, which is reflected by a reduced IgG1 IC-binding in macrophages of CII/CFA-immunized DBA/1 mice.

Long-term adaptation to prism-induced inversion of the retinal images

For 1 week, healthy human participants ( n=7) were devoid of normal vision by exposure to prism lenses that optically rotated their perceived world around the line of sight by 180 degrees. Adaptation to such prisms involved sustained and vigorous practice of the ability to redirect the unadapted efferent motor command; because prior to all visually guided movements, the to-be-executed efferent command was based on incorrect (prismatically reversed) spatial information. The time course of this sort of adaptation was systematically explored in Cooper-Shepard mental rotation (MR) tests and in naturalistic motor-tasks for the purpose of investigating whether mental rotations of the direction of the intended movement share common aspects with the process of MR. A control group ( n=7) intermittently exposed to the distorted spatial organization of the central visual field was studied in parallel. The main results were as follows: (a) the MR reaction times (RTs) day 1 with prisms appeared to be very similar to the normal RTs (day 1, no-prisms) with the one exception that subjects now responded within a prism (rotated) frame of spatial reference rather than within the environmentally upright. The visuomotor performance became grossly irregular and dysmetric. (b) The majority of the visuomotor adaptation functions began to level off on the 3rd day. (c) The increases in natural motor proficiency were accompanied by a systematic and noticeable decrease in magnitude of the MR Y-intercept obtained from the linear regression line calculated between each subject's RT and the various stimulus angles. MR slopes were stable through days 1-7 for both the experimental and control group. An increased correlation between rotational stimulus angle and RT suggested that the MR function also became progressively more tightly coupled to the stimulus angles. (d) Postadaptation measures of performance indicated the occurrence of selective and minimal adaptation in the natural motor tasks only. It is suggested that these results reflect an improved attentional (strategic) ability to replace incorrect (error producing) control signals with correct (error reducing) control signals. As a result, perceptual-motor start-up processes directly related to spatial coding and to the planning, initiation and correction of the intended direction of motor-or-mental movement improved while the subprocess ("stage") concerned with transformations of such movements remained unchanged. Visuomotor adaptation to inverting prisms engages, and thereby stimulates, a cortical system also invoked in the preparatory process of MR.

Importance of CpG dinucleotides in activation of natural IFN-alpha-producing cells by a lupus-related oligodeoxynucleotide

The oligodeoxyribonucleotide (ODN) 5'-TTTTCAATTCGAAGATGAAT-3' (ODN H), identified in systemic lupus erythematosus (SLE) serum, induced the production of interferon (IFN)-alpha in human peripheral blood mononuclear cells (PBMC) when combined with lipofectin. Flow cytometric analysis with staining for surface antigens and intracellular IFN-alpha, showed that the IFN-alpha-producing cells (IPC) were the natural IPC, also termed type 2 dendritic cell precursors (pDC2) or plasmacytoid monocytes. The importance of unmethylated CpG dinucleotides for the interferogenic activity of ODN was studied. Methylation of CpG impaired the activity of single-stranded (ss) ODN H, but increased that of the complementary ssODN I. Furthermore, CpG-methylated double-stranded (ds) ODN Hmet-Imet lost, but hemimethylated dsODN H-Imet retained interferogenic activity. Inversion of the CpG to GpC had no effect on the interferogenic activity of ssODN H, increased that of ssODN I, however abolished the activity of dsODN H-I. Alteration of the CpG in ODN H to ApG and in the ODN I to CpT destroyed their activity. The induction of IFN-alpha is therefore sequence-specific, but unmethylated CpGs are not always required, especially not in ssODNs. Interferogenic DNA sequences could therefore be more frequent in eukaryotic genomes than previously thought and their capacity to activate natural IPC may have implications for immune responses to microbial antigens and nuclear autoantigens.

Blocking of human anti-pig xenoantibodies by soluble GAL alpha 1-3Gal and Gal alpha 1-2Gal disaccharides; studies in a pig kidney in vitro perfusion model

Depletion of anti-pig xenoantibodies reduces cell cytotoxicity of human serum to pig endothelial cells and lymphocytes. The aim of this study was to test, in a pig kidney xenoperfusion model, the ability of soluble alpha Gal terminated disaccharides to prevent the hyperacute rejection process in an organ. Porcine kidneys were perfused with whole human blood lacking saccharide and blood supplemented with Gal alpha 1-3GAL, Gal alpha 1-2Gal and lactose. Parameters evaluated were, urine production, renal blood flow, vascular resistance, renal clearance, blood cell counts, xenoantibody titers, complement activation and histopathology. The blood flow was higher in the Gal alpha 1-3Gal (155 +/- 31 ml/min x 100 g-1 kidney tissue) group compared to Gal alpha 1-2Gal (138 +/- 16), lactose (92 +/- 78) and controls (69 +/- 16), When calculated as percent of the blood flow value at 1 min, the blood flow at 30 min was 157% for the Gal alpha 1-3Gal and for 187% the Gal alpha 1-2Gal. The corresponding values for the lactose and control groups were 102% and 74%, respectively. Urine production in the lactose/control groups was lower (0.7 ml/min x 100 g-1 kidney tissue) compared to Gal alpha 1-3Gal (3.0) and Gal alpha 1-2Gal (3.7). Urine sodium excretion was reduced in the lactose/control groups, compared to the Gal alpha alpha 1-groups during the perfusions. An increase in urine potassium excretion was found in the Gal alpha alpha 1-groups while a reduction occurred in the lactose/control experiments. An initial 40-50% reduction in platelet count was observed in all groups while the leukocyte count showed a continuous decrease. Immunohistochemistry revealed less deposition of IgM, IgG, C3 and C1 q in the Gal alpha alpha 1-saccharide groups compared to the lactose/control groups. Soluble Gal alpha a1-disaccharides improved both functional and histological parameters. However, significant pathological changes were still present indicating that this approach to inhibit HAR must be used in combination with additional therapeutic approaches such as solid phase xenoantibody immunoadsorption and blocking of complement activation.

CGMP increases in satellite cells of nitric oxide synthase-containing sensory ganglia

cGMP and the enzymes, nitric oxide synthase (NOS) and heme oxygenase-1 (HO-1), the products of which stimulate soluble guanylyl cyclase activity, were investigated in cultured dorsal root ganglia (DRG), and nodose ganglia of adult rats. A dramatic increase of cGMP-positive satellite cells in ganglia cultured for 24 or 48 h was observed, particularly in Th8-L2 DRG and in nodose ganglia. These ganglia also contained most NOS-positive neurones, as reflected by NADPH-diaphorase histochemistry. HO-1 immunoreactivity increased in satellite cells, but in different cells to those in which cGMP increased. These results suggest that both NO and CO could be involved in signalling between neurones and satellite cells in sensory ganglia during regeneration.

Heme oxygenase-1, heme oxygenase-2 and biliverdin reductase in peripheral ganglia from rat, expression and plasticity

The expression of inducible and constitutive heme oxygenase and biliverdin reductase was studied in normal and cultured peripheral ganglia from adult rats, using immunocytochemistry and in situ hybridization. Dramatic changes were induced by one to two days' culturing of dorsal root ganglia, nodose ganglia, otic ganglia, sphenopalatine ganglia and superior cervical ganglia. An up-regulation of inducible heme oxygenase was found in satellite cells of the cultured nodose ganglia, dorsal root ganglia, sphenopalatine ganglia and otic ganglia, whereas only a few satellite cells in the superior cervical ganglia responded with an increase in inducible heme oxygenase immunoreactivity. In the superior cervical ganglia inducible heme oxygenase also appeared in a subpopulation of macrophages. During culturing, expression of inducible heme oxygenase immunoreactivity also increased in axons and in nerve cell bodies. In situ hybridization corroborated the immunocytochemical findings, revealing a strong up-regulation of inducible heme oxygenase messenger RNA in satellite cells, and less pronounced up-regulation in nerve cell bodies. Constitutive heme oxygenase immunoreactivity was found in most neurons in all of the ganglia studied. No significant changes in constitutive heme oxygenase immunoreactivity could be observed in cultured ganglia. Biliverdin reductase immunoreactivity was barely detectable in any of the normal ganglia; however, after culturing it appeared in axons, single nerve cell bodies and nerve cell nuclei. The results show that inducible heme oxygenase is up-regulated in peripheral ganglia after axonal injury, and suggest a role for carbon monoxide in cellular signaling and a requirement for the antioxidant (bilirubin) during the regeneration process.

Intravenous synthetic alphaGal saccharides delay hyperacute rejection following pig-to-baboon heart transplantation

Several oligosaccharides containing the terminal structure Gal(alpha)1-3Gal (alphaGal) and different side chains were tested in vitro for their ability to block natural anti(alpha)Gal antibodies. A di-and a trisaccharide (di(alpha)Gal and tri(alpha)Gal) were selected. A blood group B baboon, having IgG and IgM natural antipig titers of 1:256 and 1:1024 and a hemolytic titer (to pig red blood cells, RBCs) of 1:8, was chosen to measure pharmacokinetic parameters of the saccharides and to assess the extent of in vivo neutralization of the antibodies. Three grams each of the di(alpha)Gal and the tri(alpha)Gal dissolved in saline were administered by bolus intravenous (i.v.) injection. Blood samples were collected at various times and urine was collected at 8 and 24 h. Plasma and urine concentrations of the alphaGal saccharides were estimated by an ELISA specially developed for this study. A fast distribution phase followed by equilibrium and excretion phases were observed, indicating a T1/2 in the order of 1 h. Fifty-eight per cent of the saccharides were recovered in the urine within 24 h. Determination of antipig antibody binding by FACS analysis and of serum cytotoxicity titers for pig endothelial cells demonstrated that a 70% reduction in binding and cytotoxicity could be achieved with plasma saccharide levels of 300-400 microg/ml. Six months later, a pig heart was transplanted heterotopically into the baboon. A 3-g bolus of the saccharide mixture (1.5 g of each saccharide) was given i.v. before allowing blood reperfusion of the transplanted heart, followed by an i.v. infusion of 1 g/hr for 1 hr and 0.5 g/hr for the 3 succeeding hours. Blood concentrations of the saccharides, CH50, hematology and cytotoxicity for PK15 cells were estimated in blood samples taken at various times. Heart function was observed to be satisfactory for 8 h, but was found to have ceased at 18 h. Myocardial biopsies taken at 3 and 5 h showed congestion only, suggestive of minimal vascular rejection, but by 18 h demonstrated severe vascular rejection. In conclusion, alphaGal saccharide therapy given for a period of 4 h delayed, but did not totally prevent, the development of vascular rejection in the pig-to-baboon heart transplant model. alphaGal saccharide therapy may be one of several useful approaches for the prevention of hyperacute rejection in pig-to-primate organ transplantation.

Soluble saccharides block the inhibition of agonist-induced human platelet aggregation observed after in vitro incubation of human platelet-rich plasma with porcine aortic endothelial cells

Platelet aggregation is a prominent feature in the hyperacute process of vascularized allografts and xenografts. In a study of extracorporeal connection of pig kidneys to the blood circulation of human volunteers, we observed in one case considerable destruction of human platelets in the pig kidney without signs of hyperacute rejection or microthrombi formation. In the present study, we have investigated the agonist-induced aggregation of human platelets in mixtures with porcine aortic endothelial cells (PAEC). In vitro incubation of human platelet-rich plasma (PRP) with PAEC inhibited platelet aggregation induced by ADP, collagen and arachidonic acid in a time-dependent manner and partially inhibited adrenalin-induced aggregation. Aggregation of the human platelets could not be induced by high concentrations of ADP (20 microM) to overcome the inhibition capacity of the PAEC. The PAEC inhibiting effect could be transferred by the supernatants of PAEC/PRP and PAEC/PPP incubation mixtures. Preincubation of the PAEC with aspirin, but not with NG-methyl-L-Arg, reduced the aggregation inhibitory effect. Control experiments mixing human umbilical vein endothelial cells (HUVEC) and human PRP or mixing porcine PRP and PAEC did not elicit any inhibition of ADP-induced platelet aggregation. The aggregation inhibition effect could partially be blocked by preincubation of PRP with soluble Gal alpha 1-3Gal, Gal alpha 1-3 beta 1-4GlcNAc, lactose, galactose, and glucose, but not by lactosamine, galactosamine, or glucosamine. The Gal alpha 1-3Gal disaccharide was most effective in blocking aggregation inhibition, and to a similar extent as its ability to block the human anti-pig lymphocytotoxicity reaction. In conclusion, the data indicate that PAEC, upon stimulation by human anti-pig xenoantibodies in a nondynamic system, inhibits agonist-induced human platelet aggregation, and that this effect is probably at least partially caused by prostacyclin released from the PAEC.

Differential macrophage responses following pre- and postganglionic axotomy

Here we report that macrophages in the rat superior cervical ganglia (SCG) respond differently to pre- and postganglionic axotomy. Postganglionic axotomy results in a rapid activation of resident macrophages, as measured by inducible nitric oxide synthase (iNOS) immunoreactivity, and a massive invasion by macrophages. Following preganglionic lesion there was no such rapid activation and the macrophage invasion was of much lower magnitude. A subpopulation of the macrophages also expressed haem oxygenase-1 (HO-1). The results are compatible with a model in which macrophages or their products, including nitric oxide (NO) and carbon monoxide (CO) could be important for induction of early changes in the nerve cell body, like an altered neuropeptide synthesis, which has been shown to accompany the regenerative response in peripheral ganglia.

Biotinylated platelets have an impaired response to agonists as evidenced by in vitro platelet aggregation tests

Biotinylation of platelets, using a water soluble biotin analogue which reacts with primary amines, has been proposed to be a reliable technique for study of in vivo survival of platelets and their subpopulations. The information about the influence of this technique on platelet function has been limited. In the present work we studied the effect of in vitro biotinylation on platelet function and activation. Washed human platelets, at a concentration of 1 x 10(9)/L, were biotinylated with five different concentrations of sulfo-NHS-biotin or NHS-LC-biotin, ranging from 0 to 5 mM. The degree of platelet activation during and after biotinylation was monitored by measuring the externalization of P-selectin, and the platelet function was evaluated by aggregometry. It was observed that biotinylated platelets, in a dose dependent manner, displayed an impaired aggregation response. A slight increase in platelet membrane P-selectin occurred during the labelling procedure.

[Acute otitis media at the Garethabaer Primary Health Care Centre, Iceland in 1990 and 1995. Prevalence and use of antibiotics.]

INTRODUCTION

Acute otitis media is a common health problem in Iceland. The prevalence in the urban areas is unknown. Last years, the choice of antibiotics has been widely discussed and clinical guidelines and prices have been used to influence the use of antibiotics.

OBJECTIVE

To study the prevalence of acute otitis media in an urban setting in Iceland and the use of antibiotics.

MATERIAL AND METHODS

Children 0-5 years old were studied in a retrospective way. The material from the only health centre in the community was studied by using the computerised health records of 1990 and 1995 where the diagnosis of acute otitis media had been given. The prevalence of acute otitis media was studied as well as prescriptions of antibiotics in 134 randomly selected cases from each year, totally 268 cases.

RESULTS

In the year 199015% of the children younger than one year old were given the diagnosis acute otitis media, 22.4% in 1995. The prevalence was higher among boys. Amoxicillin was the most frequently used drug in both years. The use of broad-spectrum antibiotics increased over the period.

CONCLUSION

Acute otitis media is one of the most common health problems presented to general practitioners and is the most common reason for antibiotics given to children. The choices of antibiotics seem to be in accordance with the national recommendations.

Acute bronchitis in adults. How close do we come to its aetiology in general practice?

OBJECTIVE

To investigate how close we can come to the aetiology of acute bronchitis in adults in a primary care setting.

DESIGN

Prospective study.

SETTING

General practice population in Gardabaer district, south-western Iceland.

SUBJECTS

140 patients > or = 16 years old who were diagnosed as having acute bronchitis during a two-year period (1992-1993).

MAIN OUTCOME MEASURES

Laboratory investigations (twice with a minimum four-week interval), used in general practice to analyse respiratory tract infections. They included serology for Chlamydia pneumoniae, Mycoplasma pneumoniae, respiratory tract viruses, and the level of C-reactive protein.

RESULTS

Of a total of 140 patients, two blood samples were taken on scheduled time in 113 patients. Serology confirmed recent infection in 18 (16%) of these patients. Only two (2%) had a bacterial infection (one C. pneumoniae, one M. pneumoniae). The others (84%) did not have a significant increase in antibody titres. Only four (4%) had C-reactive protein levels higher than 48 mg/l.

CONCLUSIONS

The study indicates that it is difficult to come close to a precise aetiology with respect to infectious agents of acute bronchitis in general practice. We conclude that the disease is rarely caused by atypical bacteria such as C. pneumoniae and M. pneumoniae, and rarely caused by bacterial infections severe enough significantly to increase the level of C-reactive protein.

Oh, for a little humanity

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Inducible nitric oxide synthase increases in regenerating rat ganglia

Nitric oxide synthase (NOS) exists in several isoforms. In this study we used immunocytochemistry to investigate one isoform, inducible NOS (iNOS), in the nodose ganglia (NG) and in the superior cervical ganglia (SCG) of the rat. iNOS was present in many neurones of the NG, while no iNOS-positive cells could be observed in the SCG. At 24 and 48 h following a crush lesion to the vagus nerve, expression of iNOS-immunoreactivity had increased in the NG. iNOS-immunoreactivity increased in both the NG and SCG of ganglia cultured for 24 and 48 h. The results show that an increase in iNOS-immunoreactivity accompanies regenerative processes in two peripheral ganglia, suggesting that nitric oxide, the product of iNOS activity, could be involved in nerve regeneration.

Treatment of rheumatoid arthritis--does it affect society's cost for the disease?

To assess whether the treatment of rheumatoid arthritis reduces the cost to society of the disease, 62 patients were studied retrospectively over an 18 month period. The first 6 months (period 1) was the time before treatment with remission-inducing drugs (RID). The following 6 month period (period 2) was the time when RID treatment was started and suitable doses were evaluated. The last 6 month period (period 3) was the follow-up period when the results of the treatment were evaluated. The cost for drugs, surgical treatment, out-patient visits, blood tests and hospitalization days during periods 2 and 3 was calculated as 1.6 million SEK. During the same period, the cost for loss of productivity to society was reduced by 1.5 million SEK, assuming that the cost to society would have been unchanged, compared to period 1, if therapy had not been given. In a small group of patients who entered remission, the net saving for society exceeded the cost of treatment. The study indicates that the treatment of rheumatoid arthritis can lead to a reduced cost to society.

[Chronic bronchitis among 50 and 80 years old males in Iceland. Prevalence and quality of life.]

OBJECTIVE

The mortality from chronic bronchitis has been increasing in Iceland during the last decades. Little is however known about the prevalence of this disease and the objective of this study was to find the prevalence of chronic bronchitis in Iceland.

MATERIAL AND METHODS

In this study a postal questionnaire was sent to all Icelandic males born in the years 1913 (N=388) and 1943 (N=1297) who were alive on the 1st November 1993, asking about several physical symptoms, including symptoms of chronic bronchitis. The response rate was 69.7%.

RESULTS

Altogether 7.1% of 50 years old males and 16.7% of 80 years old males had a history of daily sputum expectoration for at least three months during the last two years. These individuals with chronic bronchitis had a higher prevalence of other respiratory symptoms, such as coughing, wheezing or whistling. History of dyspnea was much higher among those with symptoms of chronic bronchitis. They also complained more often of sleep disturbances and found themselves more stressed than those without symptoms of chronic bronchitis.

CONCLUSION

Our study indicates that chronic bronchitis is a frequent illness among Icelandic males. Men with chronic bronchitis frequently have a decreased quality of life, difficulties to move and frequently sleep complaints.

Invading and resident macrophages in the regenerating rat vagus nerve in vivo and in vitro

Invading and resident macrophages were studied in the regenerating rat vagus nerve in vivo and in vitro, using antibodies to invading (EDI) and resident (ED2) macrophages. Fresh vagus nerves contained no EDI positive macrophages as revealed by immunocytochemical staining. In crush lesioned nerves in vivo, the number of EDI positive cells around and distal to the crush lesion, increased dramatically with time. Interestingly, EDI positive cells, although few, appeared in the cultured vagus nerves subjected to a crush lesion. Resident ED2 positive macrophages were abundant in fresh nerves. In vivo, there was a small increase of ED2 positive macrophages at the crush area as regeneration proceeded. In contrast, no increase was observed in vitro and after 3 days no ED2 stained macrophages were found. Immunocytochemical staining for low-affinity NGF-receptors showed a dramatic increase at the crush and distal to it in vivo, while in vitro, the receptors were upregulated along the entire nerve. The results suggest that invading macrophages may not be crucial for the initial and early outgrowth of sensory nerve fibres in peripheral nerves.

Effects of temperature and dietary n-3 and n-6 fatty acids on endocytic processes in isolated rainbow trout (Oncorhynchus mykiss, Walbaum) hepatocytes

Effects of different incubation temperatures (2, 8, 14 and 20°C) and hepatocyte membrane fatty acid composition on the rate of internalization and lysosomal degradation of the ligand, mannosylated albumin, that is taken up by receptor-mediated endocytosis, were investigated in rainbow trout (Oncorhynchus mykiss, Walbaum). The fish were kept at a water temperature ranging from 9 to 14°C and fed pelleted diets coated with either capelin oil (control), EPA/DHA-concentrate (rich in n-3 polyunsaturated fatty acids) or soybean oil (rich in n-6 unsaturated fatty acids) for at least 3 months prior to sampling. The endocytic uptake mediated by the mannose receptor was very efficient at all temperatures studied. Lysosomal degradation, on the other hand, came to a halt below 8°C. The activation energies for uptake and degradation were 54.6 and 164.2 kJ/mol respectively. No negative effects of increased amounts of either n-3 or n-6 fatty acids were observed on the endocytic parameters studied. On the contrary, multivariate analysis indicated a positive relationship between high levels of n-6 fatty acids and low unsaturation index in the phosphatidylcholine (PC) fraction of the hepatocytes and the internalization rate of 2°C, meaning that the rate of receptor-mediated endocytosis may be affected by membrane fatty acid composition.

Bovine histidine-rich glycoprotein is a substrate for bovine plasma factor XIIIa

Histidine-rich glycoprotein was purified from bovine plasma and the identity of the protein confirmed through amino acid sequencing. Activated bovine factor XIIIa catalyzed the incorporation of 1 nmol of 1,4-[14C]putrescine into 1 nmol of bovine histidine-rich glycoprotein, showing that histidine-rich glycoprotein has the ability to participate in transglutaminase-catalyzed reactions in vivo.

Low iron-binding capacity as a risk factor for myocardial infarction

BACKGROUND

In a recent Finnish study, ferritin was suggested to be an independent risk factor for acute myocardial infarction. This study suggested that high levels of iron stores might thus be atherogenic and possibly explain partly the sex difference in the incidence of ischemic heart disease.

METHODS AND RESULTS

A randomly selected group (n = 2036), men and women aged 25 to 74 years, were examined between June and September 1983. All classic risk factors for coronary artery disease were measured as well as basic hematologic parameters and the parameters of iron metabolism, ie, iron, total iron-binding capacity (TIBC), and ferritin. During the follow-up for 8.5 years, 81 subjects experienced acute myocardial infarction (63 men and 18 women). The differences in the iron parameters between men and women were almost exclusively seen in ferritin values (198 micrograms/L in men and 91 micrograms/L in women), whereas small differences were seen in TIBC. The Cox proportional hazards model was used to estimate the contribution of independent variables to the risk of myocardial infarction. TIBC was found to be a strong independent negative risk factor in men (RR = 0.95; 95% CI, 0.92 to 0.98), whereas ferritin (RR = 0.999; 95% CI, 0.997 to 1.001) or other iron parameters had no significant predictive power. Each increase in TIBC of 1 mumol/L was associated with a 5.1% decrease in the risk of myocardial infarction. The classic major risk factors, ie, blood pressure, smoking, total cholesterol, and high-density lipoprotein, had significant independent correlation with myocardial infarction. When Cox multivariate analysis was carried out on both sexes combined, TIBC was still an independent negative risk factor, and the logarithmic transform of ferritin had a weak negative correlation but was not statistically significant. Sex was in this group still a very strong risk factor after taking into account all classic risk factors as well as the parameters of iron metabolism.

CONCLUSIONS

This study suggests that transferrin, measured as TIBC, is an independent negative risk factor for myocardial infarction. Other parameters of iron metabolism, including ferritin, were not found to contribute to the risk.

Characterization of two distinct pathways of endocytosis of ricin by rat liver endothelial cells

We have studied the characteristics of internalization and intracellular transport of ricin via two distinct pathways in rat liver endothelial cells (EC), i.e., via binding to mannose receptors and surface galactosyl-residues, respectively. Treatments that inhibit endocytosis from coated pits, i.e., hyperosmolarity and acidification of the cytoplasm, decreased uptake via mannose receptors much more than uptake via galactosyl-residues, indicating that mannose receptors are largely internalized from coated pits, whereas internalization via galactosyl-residues is to a significant extent independent of coated pits. Uptake of ricin via mannose receptors was strongly inhibited by NH4Cl and monensin, and accordingly, NH4Cl protected the cells against ricin intoxication via mannose receptors. On the other hand, uptake via galactosyl-residues was not significantly inhibited by NH4Cl or monensin, and NH4Cl even sensitized the cells to intoxication via this pathway. Brefeldin A, which did not affect ricin uptake, protected the cells against ricin intoxication via either pathway. Protein synthesis in the EC was efficiently inhibited by ricin, even after very short periods of uptake at low ricin concentrations. The onset of protein synthesis inhibition was more rapid upon internalization of ricin via mannose receptors than via galactosyl-residues. Also, ricin internalized via mannose receptors was more efficiently transported from endosomes to lysosomes than ricin internalized via galactosyl-residues. Partial blocking of the galactosyl-binding sites of ricin caused a reduction in the extent of recycling of ricin from endosomes to the cell surface (retroendocytosis), indicating that binding of ricin to membrane galactosyl-residues, which is relatively stable at the slightly acidic pH of endosomes, is an important determinant of the intracellular handling of ricin. We suggest that the observed difference in the transport from endosomes to lysosomes between the two internalization pathways is related to the different stability of the two binding mechanisms at endosomal pH.

Receptor-mediated endocytosis of ricin in rat liver endothelial cells. An immunocytochemical study

The endocytic pathway of ricin in sinusoidal liver endothelial cells (EC) was traced by means of immunocytochemical labeling of ultrathin cryosections. Ricin, a highly mannosylated glycoprotein, is internalized mainly by receptor-mediated endocytosis via the mannose receptor in the EC. Labeling of specimens fixed at different time points after injection of ligand showed that several subcellular compartments are involved in processing of endocytosed ricin. One minute after injection ricin is seen in coated pits, coated vesicles and cisternal-shaped endosomes. After 6 min, the ligand associates with electron-dense, spherical vesicles and electron-lucent vesicles, presumably representing late endosomes. In the same time period we observed labeling in the vicinity of the Golgi stack. At later time points, ricin is increasingly localized in lysosomes. Both late endosomes and lysosomes showed labeling for Igp120, the lysosomal membrane glycoprotein. To compare uptake of ricin with another mannosylated ligand, we coinjected ricin and mannosylated colloidal gold particles (Man-Aun). Man-Au20, injected 24 h before fixation as a marker for late endocytic compartments, was found in two distinct compartments, presumably representing late endosomes and lysosomes. The distribution of ricin and Man-Au10, the latter injected 15 min before fixation, in early endosomes was strikingly different, indicating that the structure of this compartment is important in the process of sorting of ligand and receptor.

Bovine factor XIIa inhibitor

Bovine factor XIIa inhibitor was purified by an improved method employing affinity for heparin. N-terminal amino acid sequencing revealed a unique sequence without homology to any other known protein sequences. Peptide sequencing, however, showed that a part of the bovine factor XIIa inhibitor was homologous to human C1-inhibitor with a fraction of identical amino acid residues around 70%. Deglycosylation studies and carbohydrate analysis showed the presence of N- and O-linked carbohydrate. Bovine factor XIIa inhibitor did not inhibit plasma kallikrein and trypsin. The reactive site comprised an Arg-Asn bond, and represents the first example of asparagine as a P1' residue in Serpins with well documented inhibitory activity.

Corticosteroid effect of CPH-82

A patient suffering from seronegative polyarthritis was treated with CPH-82 (Reumacon). During the treatment he developed a cushingoid appearance and endocrinological abnormalities.

Characterization of retroendocytosis in rat liver parenchymal cells and sinusoidal endothelial cells

After receptor-mediated endocytosis, internalized ligands may be recycled to the cell surface instead of being routed to lysosomes for degradation, a process termed retroendocytosis. We have investigated the kinetics and extent of retroendocytosis of neoglycoproteins after internalization via two carbohydrate-specific receptors in rat liver cells: galactose receptors in parenchymal cells (PC) and mannose receptors in sinusoidal endothelial cells (EC). Retroendocytosis in both cell types occurred with first-order kinetics, and the rate of recycling of internalized ligands was about 4 times higher in EC than in PC. As the length of the internalization pulse was increased, the extent of subsequent retroendocytosis decreased, indicating that retroendocytosis takes place from a relatively early stage in the endocytic pathway. Furthermore, as the degree of carbohydrate substitution of the neoglycoprotein ligands increased, the affinities of the receptors for the ligands and the extent of ligand retroendocytosis increased. In the EC, the relationship between degree of substitution and extent of retroendocytosis was not immediately apparent, as some of the neoglycoprotein ligands used may also bind to and be internalized by scavenger receptors on the EC, causing a decreased apparent retroendocytosis. However, when this interaction was inhibited, this relationship was restored. We conclude that retroendocytosis mainly occurs because of incomplete dissociation of ligands from receptors before receptor recycling to the cell surface and that the affinities of a receptor for its ligand at the cell surface and in the endosomal environment are major factors in determining the extent of retroendocytosis.

Complete primary structure of bovine beta 2-glycoprotein I: localization of the disulfide bridges

The complete primary structure of bovine beta 2-glycoprotein I was determined by a combination of cDNA and peptide sequencing. Bovine beta 2-glycoprotein I was purified from citrated plasma, and by sequencing selected peptides, the complete disulfide bridge patterns of the 11 disulfide bridges were established as well as the positions of the five asparagine-linked carbohydrate groups. Bovine beta 2-glycoprotein I comprises five mutually homologous domains or Short Consensus Repeats, each containing two disulfide bridges, except for the fifth most C-terminal domain which diverges from the Short Consensus Repeat consensus by containing an additional disulfide bridge. In the four N-terminal domains, the first and third and the second and fourth half-cystines are disulfide-linked, while in the fifth domain the first and fourth, the second and fifth, and the third and sixth half-cystines are disulfide-linked.

Interactions of ricin with sinusoidal endothelial rat liver cells. Different involvement of two distinct carbohydrate-specific mechanisms in surface binding and internalization

We have investigated the interactions of the plant toxin ricin with sinusoidal endothelial rat liver cells (EC). In these cells, ricin can be bound and internalized via either cell surface galactosyl residues or mannose receptors. Binding and uptake via galactosyl residues and mannose receptors was studied in the presence of mannan (1 mg/ml) and lactose (50 mM) respectively. Whereas most of the ricin binding was accounted for by cell surface galactosyl residues, uptake of ricin via mannose receptors was much more efficient than uptake via galactosyl residues. Internalized ricin is subject to extensive retroendocytosis (recycling to the cell surface from an early endocytic compartment). Retroendocytosis occurs after internalization of ricin via either pathway and to a much greater extent than for other glycoproteins taken up via mannose receptors of the EC. Hyperosmolarity (150 mM-sucrose), which is known to inhibit endocytosis from coated pits, strongly inhibited ricin uptake via mannose receptors, but had less effect on uptake via galactosyl residues. This suggests that only part of the galactose-specific uptake takes place from coated pits. Protein synthesis in EC was very sensitive to ricin [concn. causing half-maximal inhibition (IC50) = 1.3 x 10(-13) M]. Mannan was slightly more effective than lactose in protecting the EC protein synthesis from ricin toxicity.

Prevalence of iron deficiency and iron overload in the adult Icelandic population

The aim of this cross-sectional study was to estimate the prevalence of iron deficiency and overload in the adult population in Iceland, a developed Scandinavian country. The study population consisted of 4240 individuals aged 25-74 years randomly selected from the national roster. Basic hematological, S-iron, S-total iron binding capacity (TIBC), and S-ferritin measurements were obtained on 2588 individuals (61.0%). The results indicated unusually large iron stores in the adult Icelandic population and significantly larger iron stores in the rural compared to the urban population. Iron deficiency was rare except in urban premenopausal women, where 1 in 4 showed evidence of iron deficiency and 3.2% had iron deficiency anemia. Seven patients with hereditary hemochromatosis were identified from a subgroup of 1887 subjects, resulting in a prevalence of 0.37%. Two of the hereditary hemochromatosis patients had been gastrectomized. Measures to improve the iron balance in urban premenopausal women cannot therefore include increased iron fortification of food but must be more directed towards the target group.

Histidine-rich glycoprotein inhibits contact activation of blood coagulation

Histidine-rich glycoprotein has been purified from bovine plasma employing two different purification procedures. The first procedure was one-step ion-exchange chromatography using phosphocellulose, while the second procedure involved fractionation using polyethyleneglycol 6000 followed by column chromatography employing CM-Sepharose and heparin-Sepharose. The effect of purified bovine histidine-rich glycoprotein on the contact activation of blood coagulation was studied in human plasma by using as activating surface either an ellagic acid-phospholipid suspension (Cephotest) or sulfatide. Contact activation was monitored by the generation of amidolytic activity towards a synthetic chromogenic substrate (S-2302) for factor XIIa and plasma kallikrein. Bovine histidine-rich glycoprotein inhibits the contact activation induced by both of these activating surfaces.

Extremely rapid endocytosis mediated by the mannose receptor of sinusoidal endothelial rat liver cells

Isolated sinusoidal endothelial rat liver cells (EC) in suspension bound and internalized ovalbumin, a mannose-terminated glycoprotein, in a saturable manner. The binding and uptake were Ca2+-dependent and were effectively inhibited by alpha-methyl mannoside and yeast mannan, but not by galactose or asialoglycoproteins. This corresponds to the binding specificity described for the mannose receptor of macrophages and non-parenchymal liver cells. Binding studies indicated a surface pool of 20,000-25,000 mannose receptors per cell, with a dissociation constant of 6 x 10(-8) M. Uptake and degradation of ovalbumin by isolated EC were inhibited by weak bases and ionophores which inhibit acidification of endocytic vesicles and dissociation of receptor-ligand complexes. Cycloheximide had no effect on uptake or degradation. Degradation, but not uptake, was inhibited by leupeptin. We conclude that ovalbumin dissociates from the mannose receptors in the endosomal compartment and the receptors are recycled to the cell surface, while the ovalbumin is directed to the lysosomes for degradation. A fraction of the internalized ovalbumin was recycled intact to the cell surface and escaped degradation (retroendocytosis). The rate of internalization of ovalbumin by isolated EC was very fast, with a Ke (endocytotic rate constant) of 4.12 min-1, which corresponds to a half-life of 10 s for the surface pool of receptor-ligand complexes. To our knowledge, this is the highest Ke reported for a receptor-mediated endocytosis system.

Contact activation of blood coagulation is inhibited by plasma factor XIII b-chain

The effect of the purified bovine plasma factor XIII b-chain on contact activation of blood coagulation was studied in human and bovine plasma using either an ellagic acid-phospholipid suspension (Cephotest) or dextran sulfate as activating surface. Contact activation was monitored by the generation of amidolytic activity towards a synthetic chromogenic substrate (S-2302) for factor XIIa and plasma kallikrein. The factor XIII b-chain, which is released from tetrameric factor XIII (a2b2) in the late stages of blood coagulation, inhibits contact activation induced by both activation surfaces mentioned. It was shown that a 5 min preincubation of the factor XIII b-chain with the activation surface increases its inhibitory effect. Light scattering measurements indicated a concurrent binding of the factor XIII b-chain to the Cephotest material. Because factor XIII (a2b2) itself had no such inhibitory activity, the present finding that the factor XIII b-chain inhibits contact activation may point to a novel feed-back inhibition mechanism of blood coagulation.

Primary structure of tetranectin, a plasminogen kringle 4 binding plasma protein: homology with asialoglycoprotein receptors and cartilage proteoglycan core protein

Tetranectin binds to plasminogen and to isolated kringle 4 [Clemmensen, I., Petersen, L. C., & Kluft, C. (1986) Eur. J. Biochem. 156, 327-333], apparently to its lysine-binding site. Each of the four identical chains consists of 181 amino acid residues. The three intrachain disulfide bonds connect Cys residues 50-60, 77-176, and 152-168. The tetranectin sequence is homologous (17-24% identical positions) with those parts of the asialoglycoprotein receptor family that are considered to be extracellular. Tetranectin has no structures corresponding to those parts of the receptors considered to be intracellular and membrane anchoring. The sequence of tetranectin is also homologous (22-23% identical positions) with the C-terminal globular domain of the core protein of the cartilage proteoglycan. All six Cys residues in tetranectin are located at positions that are also Cys residues in this proteoglycan. Therefore, a plausible disulfide bond pattern can now be proposed for both the asialoglycoprotein receptors and the C-terminal domain of the proteoglycan core protein. No covalently bound carbohydrate has been found.

Disulphide bridges of bovine factor X

Evidence is presented for the disulphide bridges in bovine Factor X. The protein was degraded by chemical and enzymic means, and all 12 disulphide bridges were isolated in separate peptides except for bridges nos. 6/7 in the light chain. All the disulphide bridges were found to be in positions corresponding to those found in other homologous domains. This report is the first verification of an epidermal-growth-factor-homologous domain having the same disulphide-bonding pattern as that found in mouse epidermal growth factor.

Complete primary structure of bovine plasma fibronectin

The primary structure of the 2265 residues of bovine plasma fibronectin has been completed. The new sequences reported in this paper are residues 600-868 (269 residues), 1138-1217 (80 residues), 1518-1599 (82 residues) and 1868-2061 (194 residues). These sequences constitute six type III homology units and two non-homologous connecting strands. Thus, there are fifteen type III homology units in plasma fibronectin. Evidence for two of the three splice variants found in rat liver cells [Schwarzbauer et al. (1983) Cell 35, 421-431] was obtained. No indication of the 'extra' type III domain present in some human fibroblast fibronectins [Kornblihtt et al. (1984) EMBO J. 3, 221-226] was found. Three carbohydrate groups (two glucosamine-based and one galactosamine-based) were identified, giving a total of eight carbohydrate groups in the longest splice variant of bovine plasma fibronectin. A second free sulfhydryl group (cysteine) was identified. This cysteine, like the first, is in a type III homology unit. HPLC patterns of peptides obtained from the C-terminal 6-kDa fragment suggested that the interchain bridge pattern of fibronectin is antiparallel. The bovine plasma fibronectin sequence is highly homologous to the human cellular fibronectin sequence deduced from the cDNA sequence [Kornblihtt et al. (1985) EMBO J. 4, 1755-1759].

Donor and acceptor splice signals within an exon of the human fibronectin gene: a new type of differential splicing

We have sequenced that area of a human fibronectin gene clone which codes for a connecting strand separating the last two areas of the type III homology. The gene has a complex exon with two 'AG' acceptor sites. One of these can be used (exon subdivision). In addition 93 basepairs inside the exon are sometimes spliced out as an intron. This is the third differential splicing found in the fibronectin gene transcript and it represents a new type of differential splicing.

Purification and complete primary structures of the heparin-, cell-, and DNA-binding domains of bovine plasma fibronectin

The complete amino acid sequences of the heparin-, cell- and DNA-binding domains of bovine plasma fibronectin have been determined. The fragments were generated from the 170-kDa central plasmic fragment by extensive digestion with chymotrypsin, and they contain 268, 300 and 269 amino acid residues, respectively. No half-cystines or cysteines were found in these sequences. A glucosamine-based oligosaccharide group is attached to Asn-108 in the sequence of the DNA-binding domain. Only one of the three types of internal homology found in fibronectin [Petersen et al. (1983) Proc. Natl Acad. Sci. USA 80, 137-141], namely the type III homology, occurs in these three fragments, and each of them consists of approximately three stretches of this type III homology. Part of the arrangement of peptides was derived by comparison with the partial cDNA sequence for human fibronectin recently reported [Kornblihtt et al. (1984) Nucleic Acids Res. 12, 5853-5868].