Using egg yolk in a TRIS-Equex STM paste extender for freezing of dog semen is superior to egg yolk plasma, also after addition of lecithin and catalase.

We compared the results of using egg yolk plasma (EYP) instead of egg yolk (EY) in a TRIS-based Equex STM Paste freezing extender system for dog semen [25]. We also tested whether the addition of lecithin and catalase to the EYP extenders would improve results. Fractionated semen collection was done in 17 stud dogs and the sperm rich fraction diluted with different extenders in 2 steps: (I) TRIS-fructose-citric acid extender (TRIS) containing 20% egg yolk (EY) and 3% glycerol [25], (II) TRIS containing 20% egg yolk plasma (EYP) and 3% glycerol, and (III) TRIS containing 20% EYP and 0.8% lecithin (EYP-L) and 3% glycerol. After equilibration the second dilution step was done: samples with (I) were diluted with TRIS-EY with 7% glycerol and 1% Equex STM paste [25]; samples with (II) and (III) were divided in 2 aliquots each, and one part diluted with TRIS-EYP or TRIS-EYP-L, both containing 7% glycerol and 1% Equex STM paste, and the other one part with the same extenders containing additionally 300 I.U./mL catalase. After freezing and thawing, samples were analyzed by CASA and sperm chromatin structure assay (SCSA); reactive oxygen species (ROS), degree of apoptosis and zona binding ability were determined. Semen samples with TRIS-EY with a final concentration of 5% glycerol and 0.5% Equex STM paste [25] showed best post thaw progressive motility (P), most intact cells, lowest percentage of ROS, acrosome damages, dead and apoptotic cells. Curvilinear velocity (VCL), DNA fragmentation, morphological abnormalities and zona binding ability did not differ between groups. Replacement of egg yolk by EYP increased the ROS and late apoptotic cells. Addition of lecithin and catalase to EYP containing extenders decreased motility and increased complete apoptosis. We conclude that egg yolk is superior to EYP in the here investigated extenders. The TRIS-based extender [25] with EYP could not be improved by addition of lecithin and catalase; however, in-vivo fertilization capacity of the here examined extenders remains to be investigated.

Can LDL cholesterol be too low? Possible risks of extremely low levels.

Following the continuous accumulation of evidence supporting the beneficial role of reducing low-density lipoprotein cholesterol (LDL-C) levels in the treatment and prevention of atherosclerotic cardiovascular disease and its complications, therapeutic possibilities now exist to lower LDL-C to very low levels, similar to or even lower than those seen in newborns and nonhuman species. In addition to the important task of evaluating potential side effects of such treatments, the question arises whether extremely low LDL-C levels per se may provoke adverse effects in humans. In this review, we summarize information from studies of human cellular and organ physiology, phenotypic characterization of rare genetic diseases of lipid metabolism, and experience from clinical trials. Specifically, we emphasize the importance of the robustness of the regulatory systems that maintain balanced fluxes and levels of cholesterol at both cellular and organismal levels. Even at extremely low LDL-C levels, critical capacities of steroid hormone and bile acid production are preserved, and the presence of a cholesterol blood-brain barrier protects cells in the central nervous system. Apparent relationships sometimes reported between less pronounced low LDL-C levels and disease states such as cancer, depression, infectious disease and others can generally be explained as secondary phenomena. Drug-related side effects including an increased propensity for development of type 2 diabetes occur during statin treatment, whilst further evaluation of more potent LDL-lowering treatments such as PCSK9 inhibitors is needed. Experience from the recently reported and ongoing large event-driven trials are of great interest, and further evaluation including careful analysis of cognitive functions will be important.

Beneficial effects of levosimendan on survival in patients undergoing extracorporeal membrane oxygenation after cardiovascular surgery.

BACKGROUND: The impact of levosimendan treatment on clinical outcome in patients undergoing extracorporeal membrane oxygenation (ECMO) support after cardiovascular surgery is unknown. We hypothesized that the beneficial effects of levosimendan might improve survival when adequate end-organ perfusion is ensured by concomitant ECMO therapy. We therefore studied the impact of levosimendan treatment on survival and failure of ECMO weaning in patients after cardiovascular surgery. METHODS: We enrolled a total of 240 patients undergoing veno-arterial ECMO therapy after cardiovascular surgery at a university-affiliated tertiary care centre into our observational single-centre registry. RESULTS: During a median follow-up period of 37 months (interquartile range 19-67 months), 65% of patients died. Seventy-five per cent of patients received levosimendan treatment within the first 24 h after initiation of ECMO therapy. Cox regression analysis showed an association between levosimendan treatment and successful ECMO weaning [adjusted hazard ratio (HR) 0.41; 95% confience interval (CI) 0.22-0.80; P=0.008], 30 day mortality (adjusted HR 0.52; 95% CI 0.30-0.89; P=0.016), and long-term mortality (adjusted HR 0.64; 95% CI 0.42-0.98; P=0.04). CONCLUSIONS: These data suggest an association between levosimendan treatment and improved short- and long-term survival in patients undergoing ECMO support after cardiovascular surgery.

An unexpected intriguing effect of Toll-like receptor regulator RP105 (CD180) on atherosclerosis formation with alterations on B-cell activation.

OBJECTIVE: In atherosclerosis, Toll-like receptors (TLRs) are traditionally linked to effects on tissue macrophages or foam cells. RP105, a structural TLR4 homolog, is an important regulator of TLR signaling. The effects of RP105 on TLR signaling vary for different leukocyte subsets known to be involved in atherosclerosis, making it unique in its role of either suppressing (in myeloid cells) or enhancing (in B cells) TLR-regulated inflammation in different cell types. We aimed to identify a role of TLR accessory molecule RP105 on circulating cells in atherosclerotic plaque formation. APPROACH AND RESULTS: Irradiated low density lipoprotein receptor deficient mice received RP105(-/-) or wild-type bone marrow. RP105(-/-) chimeras displayed a 57% reduced plaque burden. Interestingly, total and activated B-cell numbers were significantly reduced in RP105(-/-) chimeras. Activation of B1 B cells was unaltered, suggesting that RP105 deficiency only affected inflammatory B2 B cells. IgM levels were unaltered, but anti-oxidized low-density lipoprotein and anti-malondialdehyde-modified low-density lipoprotein IgG2c antibody levels were significantly lower in RP105(-/-) chimeras, confirming effects on B2 B cells rather than B1 B cells. Moreover, B-cell activating factor expression was reduced in spleens of RP105(-/-) chimeras. CONCLUSIONS: RP105 deficiency on circulating cells results in an intriguing unexpected TLR-associated mechanisms that decrease atherosclerotic lesion formation with alterations on proinflammatory B2 B cells.

Recruiting refugees and migrants as potential hematopoietic stem cell donors to serve patients of comparable ethnicities with rare human leucocyte antigen patterns - The BluStar.NRW project in North Western Germany.

Currently, approximately 19 million people with a migration background live in Germany. The majority of those descend from regions where the population has a genetically different distribution of HLA antigens when compared to the HLA frequencies usually found in North Western Europe. In case of severe haematological disorders of these individuals, allogeneic stem cell transplantation may be the treatment of choice. However, finding appropriate histocompatible hematopoietic stem cell donors continues to be a major challenge. If no matching sibling donors are available, there are only few suitable donors with a similar genetic background available in international blood stem cell donor registries. The "BluStar.NRW" project aimed to recruit new blood and hematopoietic stem cell donors with a migration background and to noticeably increase the number of suitable donors for patients within this group. Since December 2017, a total number of 9100 blood and stem cell donors with a migration background were recruited and typed for this project. HLA typing for HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1 was performed by Next Generation Sequencing. We assessed the proportion of rare alleles according to HLA frequency tables, as defined by a frequency of <1:1000. The rare HLA allele frequencies according to HLA frequency tables of the BluStar.NRW cohort were compared with a matched control donor cohort: Rare HLA-A, -B, -C, -DRB1 and -DQB1 alleles occurred three times more frequent than in the control group, but rare HLA-DPB1 alleles occurred more frequently in the control cohort. This difference was highly significant for all HLA alleles (p < 0.0001 for HLA-A, -B, -C, -DRB1, -DPB1; p = 0.0002 for HLA-DQB1). In addition, the distribution of rare alleles differed between the two groups. To date, 29 work-ups were initiated, 12 PBSC, one BM and three DLI were collected so far out of the BluStar.NRW cohort. The apheresis probability is twofold higher (0.18% vs. 0.07%) compared to the control group which clearly shows a serious medical need. However, 13 work-ups were cancelled in the BluStar.NRW donor cohort which represents an almost twice as higher cancellation rate (45% vs. 25%). This single registry analysis with a large sample cohort clearly indicates that hematopoietic stem cell donors with a migration background represent an adequate donor pool to serve patients of comparable ethnicity.

CHO(E)P-14 followed by alemtuzumab consolidation in untreated peripheral T cell lymphomas: final analysis of a prospective phase II trial.

The rate of long-term remissions after treatment of peripheral T cell lymphomas (PTCL) with standard CHOP-like protocols is unsatisfactory. A prospective multicenter phase II trial was initiated in untreated patients with PTCL of all International Prognostic Index-risk groups, evaluating alemtuzumab consolidation in patients with complete or good partial remission after CHO(E)P-14 induction. Twenty-nine (70.7 %) of the 41 enrolled patients received alemtuzumab consolidation (133 mg in total). The main grades 3-4 toxicities during alemtuzumab therapy were infections and neutropenia with one potentially treatment-related death. Complete responses were seen in 58.5 %, partial responses in 2.4 % and 29.3 % had progressive disease. After a median observation time of 46 months, 19 patients have died, 16 of them due to lymphoma and/or salvage therapy complications. Event-free and overall survival at 3 years in the whole intent to treat population are 32.3 and 62.5 %, respectively, and 42.4 and 75.1 % in the patients who received alemtuzumab. In conclusion, application of a short course of alemtuzumab after CHO(E)P-14 induction is feasible although complicated by severe infections. A current phase III trial, applying alemtuzumab as part of the initial chemotherapy protocol to avoid early progression, will further clarify its significance for the therapeutic outcome.

Cardiovascular risk factors: The effects of ageing and smoking on the immune system, an observational clinical study.

Currently immunomodulatory compounds are under investigation for use in patients with cardiovascular disease, caused by atherosclerosis. These trials, using recurrent cardiovascular events as endpoint, require enrollment of large patient groups. We investigated the effect of key risk factors for atherosclerosis development, ageing and smoking, on the immune system, with the objective to identify biomarkers differentiating between human populations, and potentially serving as endpoints for future phase 1B trials with immunomodulatory compounds. Blood was collected from young healthy volunteers (aged 18-25 years, n=30), young smokers (18-25 years, n=20), elderly healthy volunteers (>60 years, n=20), heavy smokers (>45 years, 15 packyears, n=11) and patients with stable coronary artery disease (CAD) (>60 years, n=27). Circulating immune cell subsets were characterized by flow cytometry, and collected plasma was evaluated by proteomics (Olink). Clear ageing effects were observed, mostly illustrated by a lower level in CD8+ and naïve CD4+ and CD8+ T cells, with an increase in CD4+ and CD8+ effector memory T cells in elderly healthy volunteers compared to young healthy volunteers. Heavy smokers showed a more inflammatory cellular phenotype, especially a shift in Th1/Th2 ratio: higher Th1 and lower Th2 percentages compared to young healthy volunteers. A significant decrease in circulating atheroprotective oxLDL-specific IgM was found in patients with CAD compared to young healthy volunteers. Elevated pro-inflammatory and chemotactic proteins TREM1 and CCL11 were observed in elderly volunteers compared to young volunteers. In addition, heavy smokers had an increase in pro-inflammatory cytokine IL-6 and lysosomal protein LAMP3. These data show that ageing and smoking are associated with an inflammatory immunophenotype, and that heavy smokers or aged individuals may serve as potential populations for future clinical trials investigating immunomodulatory drugs targeted for cardiovascular disease.

ß-catenin-independent WNT signaling in basal-like breast cancer and brain metastasis.

A role of WNT signaling for primary breast cancers of the basal-like subtype and as a predictor of brain metastasis has been described. However, a responsible WNT ligand has not been identified. To further clarify this question, we comparatively investigated 22 human breast cancer brain metastases as well as the highly invasive human breast cancer cell line MDA-MB-231 and the weakly motile MCF-7 as models for the basal-like and the luminal A subtype. WNT5A and B were found overexpressed in MDA-MB-231 cells as compared with MCF-7. This corresponded to reduction of MDA-MB-231 invasiveness by WNT inhibitors, whereas MCF-7 invasion was enhanced by recombinant WNT5B and abolished by WNT and Jun-N-terminal kinase antagonists. Expression and subcellular distribution of ß-catenin remained uninfluenced. Consistently, ß-catenin was not localized in the nuclei of brain metastases while there was strong nuclear c-Jun staining. Similar to MDA-MB-231, metastases showed expression of WNT5A/B and the alternative WNT receptors ROR1 and 2. These findings were validated using external gene expression datasets (Gene Expression Omnibus) of different breast cancer subtypes and brain metastases. Hierarchical cluster analysis yielded a close relation between basal-like cancers and brain metastases. Gene set enrichment analyses confirmed WNT pathway enrichment not only in basal-like primaries but also in cerebral metastases of all subtypes. In conclusion, WNT signaling seems highly relevant for basal-like and other subtypes of breast cancers metastasizing into the brain. ß-catenin-independent WNT signaling, presumably via ROR1-2, plays a major role in this context.

Expression of nuclear progesterone receptor, progesterone receptor membrane components 1 and 2 and prostaglandin-endoperoxide synthase 2 in the endometrium and oviduct of spontaneously ovulating cats.

Although ovulations not followed by pregnancy occur regularly in cats, differences in endometrial function between cats in the luteal and non-luteal phase have not been studied so far. Progesterone exerts its effects through a nuclear progesterone receptor (PGR) and via cell-membrane bound receptors referred to as progesterone receptor membrane component (PGRMC) 1 and 2. Progesterone receptor expression is regulated by gonadal steroid hormones and therefore may change throughout the oestrous cycle. Protein expression of PGR, PGRMC-1 and 2 and prostaglandin-endoperoxide synthase 2 (PTGS2) was analysed in the endometrium and oviduct of non-pregnant female cats in the follicular (n = 8) and luteal phase (n = 9). We hypothesized that the presence of corpora lutea (CL) is associated with downregulation of progesterone receptors and PTGS2. Cells of the luminal endometrial epithelium, endometrial stroma and oviductal epithelium were assessed by immunohistochemistry. The PGR protein expression was more pronounced in the endometrial epithelium than stroma (p < 0.001) and less pronounced in cats with a CL than without CL (p < 0.001) but did not differ between groups in the oviduct. The PTGS2 was localized only in the endometrial and oviductal epithelium and its expression was reduced in cats with CL (p = 0.001). In the endometrial epithelium, PGRMC-1 expression was reduced in cats with CL (p < 0.05). Expression of PGRMC-2 was highest in the endometrial epithelium and lowest in the endometrial stroma (p = 0.01) but did not differ between cats with and without CL. In conclusion, progesterone receptor and PTGS2 downregulation in the female cat closely resembles findings in other spontaneously ovulating domestic animal species.

Natural antibodies, intravenous immunoglobulin and their role in autoimmunity, cancer and inflammation.

Natural antibodies are produced by B lymphocytes in the absence of external antigen stimulation. With their ability to recognize self, altered self and foreign antigens, they comprise an important first-line defence against invading pathogens, but are also important for tissue homeostasis. By recognizing oligosaccharides expressed on tumour cells and modified cell surface structures accompanying necrosis, natural antibodies have an important anti-tumorigenic function. IVIg contains a wide spectrum of specificities presented in normal plasma including natural antibodies and has been shown to exert inhibitory effects on tumour cells through a subfraction of anti-vascular endothelial growth factor immunoglobulin (Ig)G antibodies with anti-angiogenic properties. IgA antibodies also have potent immunomodulatory properties, being able to both induce and suppress immune responses. IgA-mediated inhibitory function is able to inhibit several inflammatory diseases including asthma and glomerulonephritis. Autoantibodies of the IgM type, on the other hand, have shown promising results in the treatment of multiple sclerosis. These autoantibodies promote remyelination rather than modulating inflammation. Oxidation-specific epitopes, as found in atherosclerotic lesions and on apoptotic cells, comprise one important target of natural antibodies. By recognizing these epitopes, natural antibodies neutralize proinflammatory responses and mediate atheroprotection.

Oxidation-specific epitopes are important targets of innate immunity.

During the oxidation of LDL, a central pathophysiological component of atherogenesis, a wide variety of chemical and physical changes occur leading to the generation of oxidation-specific neoepitopes. These epitopes are not only immunogenic, leading to adaptive humoral responses, but are also a prominent target of multiple arcs of innate immunity. The pattern recognition receptors (PRRs) of innate immunity are germ line encoded, conserved by natural selection, and bind to pathogen-associated molecular patterns (PAMPs) common on multiple structures. However, it is not intuitive as to why they should recognize oxidation-specific neoepitopes. Yet it is clear that multiple macrophage scavenger receptors, which are classic PRRs, recognize oxidation-specific epitopes, such as those found on oxidized LDL (OxLDL). Other innate proteins, such as C-reactive protein, also bind to OxLDL. Natural antibodies (NAbs), the humoral arc of innate immunity, provide a nonredundant role in the first line of defence against pathogens, but are also believed to provide important homeostatic house-keeping functions against self-antigens. Our work demonstrates that oxidation-specific epitopes, as found on OxLDL, are a major target of NAbs. In this review, we will discuss the specific example of the prototypic NAb T15/E06, which is increased in atherosclerotic mice and mediates atheroprotection, and discuss the potential role of NAbs in atherogenesis, and in inflammation in general. We also review data that oxidation-specific epitopes are generated whenever cells undergo programmed cell death, forming a common set of PAMPs recognized by oxidation-specific PRRs on macrophages, NAbs and innate proteins. We present the hypothesis that oxidation-specific epitopes on apoptotic cells exerted evolutionary pressure for the conservation of these PRRs and also serve to maintain the expansion of a substantial proportion of NAbs directed to these stress-induced self-antigens.

Oxidized low-density lipoprotein in inflammation-driven thrombosis.

Thrombosis is the defining feature of the most prevalent causes of cardiovascular mortality, such as myocardial infarction, stroke, and pulmonary artery embolism. Although platelet activation and activation of the plasmatic coagulation system are the hallmarks of thrombus formation, inflammatory processes and the cellular responses involved are increasingly being recognized as critical modulators of thrombosis. In the context of many chronic inflammatory diseases that are associated with a high thrombotic risk, oxidized lipoproteins represent a prominent sterile trigger of inflammation. Oxidized low-density lipoprotein and its components play a central role in the initiation and progression of atherosclerotic plaques, but also in other processes that lead to thrombotic events. Moreover, dying cells and microvesicles can be decorated with some of the same oxidized lipid components that are found on oxidized lipoproteins, and thereby similar mechanisms of thromboinflammation may also be active in venous thrombosis. In this review, we summarize the current knowledge on how oxidized lipoproteins and components thereof affect the cells and pathways involved in thrombosis.

Natural antibodies to oxidation-specific epitopes: innate immune response and venous thromboembolic disease.

Essentials Natural antibodies to oxidation-specific epitopes have antithrombotic properties. We evaluated the relation between natural IgM and IgG antibodies and the venous thrombosis risk. Risk of recurrent thrombosis was higher in patients with low natural IgM antibody levels. The protective effect of high IgM levels suggests a role of innate immune response in thrombosis. SUMMARY: Background and objectives Natural antibodies to oxidation-specific epitopes protect from atherothrombotic events. Whether mechanisms of innate immunity are relevant in the pathogenesis of venous thromboembolism (VTE) is unknown. Patients/Methods We measured plasma levels of immunoglobulin M (IgM) antibodies to oxidized low-density lipoproteins (OxLDL) and phosphocholine (PC) by enzyme linked immune assay in 663 patients with unprovoked VTE, who were prospectively followed after discontinuation of anticoagulation for a median of 8.8 years. The study endpoint was recurrent VTE. Results IgM antibody levels to OxLDL and PC were higher in patients without compared to those with recurrent VTE (n = 174, 26.2%). For each doubling of OxLDL-IgM or PC-IgM the hazard ratio (HR) of recurrence was 0.88 (95% confidence interval [CI], 0.77-1.01) and 0.82 (95% CI, 0.71-0.94), respectively. After 5 years the probability of recurrence in patients with PC-IgM levels in the highest tertile (> 19.6 RLU/100 ms) was 13.0% (95% CI, 8.1-17.6%), compared with 21.1% (95% CI, 14.9-26.9%) in the middle tertile and 20.6% (95% CI, 14.7-26.0%) in the lowest tertile. The corresponding HR was 0.56 (0.39-0.82) for PC-IgM levels in the highest compared with the lowest tertile. Neither immunoglobulin G IgG antibody levels to OxLDL nor those to PC were associated with risk of VTE. Conclusion Levels of natural IgM antibodies to oxidation-specific epitopes are inversely related to the risk of VTE.

Kinetics of human connecting peptide in normal and diabetic subjects.

The metabolic clearance rate (MCR) of synthetic human connecting peptide (C-peptide) was measured with a single-dose injection technique in six normal and seven diabetic subjects and with a constant infusion technique in one normal subject. The MCR of C-peptide did not differ in normal subjects (4.4 ml/min per kg; range, 3.7-4.9) and in diabetic subjects (4.7 ml/min per kg; range, 3.7-5.8). Employment of both techniques in one subject gave similar MCR. The average half-life of C-peptide in plasma calculated from the last 1-h period of the single-dose injection studies was longer in the insulin-dependent diabetics (42.5 min; range, 39.4-48.5) than in the normal subjects (33.5 min; range, 24.9-45.3). These results indicate that the beta-cell secretory capacity of normal and insulin-dependent diabetic subjects can be compared by measuring the C-peptide concentration in peripheral venous plasma. The difference in the half-life of C-peptide in plasma between diabetics and normals suggests an altered kinetics of the disappearance of the peptide, while the overall metabolism, as expressed by the MCR, is similar.

Malondialdehyde Epitopes as Targets of Immunity and the Implications for Atherosclerosis.

Accumulating evidence suggests that oxidation-specific epitopes (OSEs) constitute a novel class of damage-associated molecular patterns (DAMPs) generated during high oxidative stress but also in the physiological process of apoptosis. To deal with the potentially harmful consequences of such epitopes, the immune system has developed several mechanisms to protect from OSEs and to orchestrate their clearance, including IgM natural antibodies and both cellular- and membrane-bound receptors. Here, we focus on malondialdehyde (MDA) epitopes as prominent examples of OSEs that trigger both innate and adaptive immune responses. First, we review the mechanisms of MDA generation, the different types of adducts on various biomolecules and provide relevant examples for physiological carriers of MDA such as apoptotic cells, microvesicles, or oxidized low-density lipoproteins. Based on recent insights, we argue that MDA epitopes contribute to the maintenance of homeostatic functions by acting as markers of elevated oxidative stress and tissue damage. We discuss multiple lines of evidence that MDA epitopes are proinflammatory and thus important targets of innate and adaptive immune responses. Finally, we illustrate the relevance of MDA epitopes in human pathologies by describing their capacity to drive inflammatory processes in atherosclerosis and highlighting protective mechanisms of immunity that could be exploited for therapeutic purposes.

Comparison of bacterial counts in expressed breast milk following standard or strict infection control regimens in neonatal intensive care units: compliance of mothers does matter.

Bacterial counts in 1466 expressed breast milk (EBM) samples from women following one of two infection control regimens (standard vs strict) were investigated. Overall, 12% of samples yielded Gram-negative bacteria, with no significant differences between the standard [11.9% (94/788)] and strict [12.1% (82/678)] regimens (P = 0.92). Significantly more samples were contaminated when expressed at home (standard regimen home/hospital: 17.9% vs 6.1%; strict regimen home/hospital: 19.6% vs 3.4%; P < 0.001). Bacterial contamination of EBM was not associated with the regimen, but was associated with the location of breast milk expression. Attempts to improve personal hygiene during milk collection seem to be of limited value. Good hygiene of collection and storage equipment is likely to be the most important way to ensure the microbiological quality of EBM.

Residual beta-cell function and its metabolic consequences.

Improvement in the sensitivity and specificity of the C-peptide immunoassay and studies of larger groups of patients have increased our knowledge of the importance of residual beta-cell function and its metabolic consequences in insulin-treated diabetic patients. During the first five to 10 years after the onset of diabetes mellitus residual beta-cell function is demonstrable in the majority of insulin-treated patients irrespective of the severity of the initial symptoms and only partly dependent on the patient's age at diagnosis. Residual beta-cell function facilitates good control. Stable patients have a higher C-peptide concentration in plasma than unstable ones, but unmeasurable C-peptide is not always associated with poor control. More data are needed before the full significance of an even minimal reserve of beta-cell function is elucidated. It also remains to be shown whether the reductive in beta-cell function in diabetic patients has a qualitative as well as quantitative component.

C-peptide response to glucagon. A test for the residual beta-cell function in diabetes mellitus.

Pancreatic beta-cell secretory activity was measured in 17 patients with insulin-dependent diabetes mellitus of less than 19 months' duration and in 10 nondiabetic subjects by means of the peripheral plasma C-peptide response to 1 mg. of glucagon I.V. The C-peptide response to a meal was also measured in the diabetic patients. Residual beta-cell function was present in all the diabetic patients as indicated by significant amounts of C-peptide in plasma. Significant increases in C-peptide were observed in 16 after glucagon stimulation and in 15 after the meal. Both absolute and relative increase in C-peptide were reduced in the diabetic patients. The increase in C-peptide was correlated to the fasting C-peptide concentration both after glucagon (r=0.86, p less than 0.001) and after the meal (r=0.66, p less than 0.01). The responses to the meal and to glucagon were correlated (r=0.77, p less than 0.005), indicating a high predictive value of the glucagon test as to how the beta-cells will respond during normal daily life.

Follow-up of women with previous GDM. Insulin, C-peptide, and proinsulin responses to oral glucose load.

Gestational diabetes mellitus (GDM) is a strong predictor of glucose intolerance later in life. Former GDM (n = 145) and control (n = 41) subjects were studied 3-4 yr after the index pregnancy. They were subjected to a 75-g oral glucose tolerance test (OGTT) with measurements of insulin, C-peptide, and proinsulin in the basal state and every 30 min for 180 min. In the former GDM group, 5 subjects (3.4%) had developed non-insulin-dependent diabetes mellitus (NIDDM), and 32 (22%) had developed impaired glucose tolerance (IGT; by World Health Organization criteria). In the control group, 2 (4%) had IGT. In the GDM group, IGT or NIDDM was significantly associated with obesity (body mass index [BMI] greater than or equal to 25 kg/m2) and earlier diagnosis of GDM during pregnancy (P less than 0.001). Nonobese (BMI less than 25 kg/m2) GDM subjects with normal glucose tolerance at follow-up had significantly higher mean glucose (P less than 0.01), insulin (P less than 0.05), and proinsulin (P less than 0.001) values during the OGTT than control subjects, whereas there was no significant difference in C-peptide values. A comparison between control subjects with normal OGTT and BMI less than 25 kg/m2 (n = 39) and GDM subjects (n = 39) selected to have a comparable area under the glucose curve, BMI, and age demonstrated no group differences in glucose, C-peptide, or insulin levels, whereas the proinsulin levels were significantly higher (P less than 0.001) during the glucose load. The molar ratio between proinsulin and insulin was also significantly higher among the former GDM subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics of human C-peptide in man.

A review of studies concerned with the metabolism of human C-peptide showed that the kidney is the major organ in C-peptide removal. The turnover rate of C-peptide was similar to that of proinsulin but considerably slower than that of insulin. An analysis of corresponding C-peptide and insulin concentrations in normal subjects after the administration of oral glucose or intravenous glucagon was used to define the relationships between the two peptides. These results show that different peripheral vein concentrations of insulin may correspond to identical C-peptide concentrations, depending on sampling conditions.