The gut microbiome drives inter- and intra-individual differences in metabolism of bioactive small molecules.

The origin of inter-individual variability in the action of bioactive small molecules from the diet is poorly understood and poses a substantial obstacle to harnessing their potential for attenuating disease risk. Epidemiological studies show that coffee lowers the risk of developing type 2 diabetes, independently of caffeine, but since coffee is a complex matrix, consumption gives rise to different classes of metabolites in vivo which in turn can affect multiple related pathways in disease development. We quantified key urinary coffee phenolic acid metabolites repeated three times in 36 volunteers, and observed the highest inter- and intra-individual variation for metabolites produced by the colonic microbiome. Notably, a urinary phenolic metabolite not requiring the action of the microbiota was positively correlated with fasting plasma insulin. These data highlight the role of the gut microbiota as the main driver of both intra- and inter-individual variation in metabolism of dietary bioactive small molecules.

In vitro enzymic hydrolysis of chlorogenic acids in coffee.

SCOPE: Coffee is rich in quinic acid esters of phenolic acids (chlorogenic acids) but also contains some free phenolic acids. A proportion of phenolic acids appear in the blood rapidly after coffee consumption due to absorption in the small intestine. We investigated in vitro whether this appearance could potentially be derived from free phenolic acids in instant coffee or from hydrolysis of chlorogenic acids by pancreatic or brush border enzymes. METHODS AND RESULTS: We quantified six free phenolic acids in instant coffees using HPLC-DAD-mass spectrometry. The highest was caffeic acid, but all were present at low levels compared to the chlorogenic acids. Roasting and decaffeination significantly reduced free phenolic acid content. We estimated, using pharmacokinetic modelling with previously published data, that the contribution of these compounds to small intestinal absorption is minimal. Hydrolysis of certain chlorogenic acids was observed with human-differentiated Caco-2 cell monolayers and with porcine pancreatin, which showed maximal rates on 3- and 5-O-caffeoylquinic acids, respectively. CONCLUSION: The amounts of certain free phenolic acids in coffee could only minimally account for small intestinal absorption based on modelling. The hydrolysis of caffeoylquinic, but not feruloylquinic acids, by enterocyte and pancreatic esterases is potentially a contributing mechanism to small intestinal absorption.

Hemostatic abnormalities and the severity of illness in patients at the onset of clinically defined sepsis. Possible indication of the degree of endothelial cell activation?

OBJECTIVE: To find out whether changes within the hemostatic system are related to the severity of illness and organ failure in patients at the onset of clinically defined sepsis and to find some indications for the contribution of endothelial cell activation or perturbation to the patient's status. The following measurements were undertaken: Acute Physiology and Chronic Health Evaluation (APACHE) II score, multiple organ failure (MOF) score, plasma levels of thrombin-antithrombin III complexes (TAT), antithrombin III (AT III), protein C antigen, factor XII, and plasminogen activator inhibitor type 1 antigen (PAI-1), neopterin, and interleukin 6 (IL-6). DESIGN: A prospective case series study. SETTING: Intensive care unit (ICU) of the Department of Internal Medicine, Justus Liebig University, Giessen, Germany. PATIENTS: 28 consecutive patients (11 females, 17 males; mean age 58 years) with clinically defined sepsis. Eleven patients were admitted from the surgical ICU (9 after elective surgery, 2 after trauma surgery). The operations were done 1-26 days (mean 14 days) prior to the onset of sepsis. MAIN RESULTS: At the onset of sepsis we found elevated plasma levels of TAT, PAI-1, neopterin, and IL-6, and lowered plasma levels of AT III, factor XII, and protein Cantigen. Neopterin, PAI-1, IL-6, and factor XII showed a statistically significant correlation with the APACHE II score. The MOF score is significantly correlated with IL-6 and neopterin. The extent of hemostatic abnormalities was related to increasing levels of IL-6. CONCLUSIONS: Clinical evidence of a septic process is most likely to be preceded by activation of the hemostatic system, the vascular endothelium, and the monocyte/macrophage system. IL-6 may have a regulatory function for hemostasis in inflammation. Laboratory monitoring could be helpful in deciding whether to start early intensive therapy in patients at risk for sepsis.

[Clinical and histologic findings after several weeks of intraocular tamponade with perfluorodecalin]. / Klinische und histologische Befunde nach mehrwöchiger intraokularer Tamponade mit Perfluordecalin.

Perfluorocarbon residues sometimes remain in the eye following vitreoretinal procedures employing liquid perfluorocarbons. According to the literature, one or two droplets do not appear to damage the ocular tissue. The question of whether this also applies to larger volumes was investigated in two eyes of two patients. Both eyes were injected with perfluorodecalin for removal of luxated lens in two patients. In one patient approximately 3 ml perfluorodecalin remained in the eye for 3 months postoperatively, in the other patient approximately 4 ml for 4 months. The eye of the first patient developed an inoperable complicated retinal detachment. The second eye developed a secondary glaucoma requiring additional cyclocryocoagulation after removal of the perfluorocarbon. Histological examination of excised retinal tissue revealed extensive destruction of the normal architecture with a marked reduction in the number of cells in the nuclear layers. It remains unclear whether these findings can be attributed to toxic or mechanical damage.

The occurrence of macrophages in the retina and periretinal tissues in ocular diseases.

Specimens obtained from eyes with various ocular diseases were examined immunohistochemically using a panel of monoclonal antibodies (Ki-M1P, K1-M4, CD68, anti-lysozyme, and anti-cytokeratins) to establish the occurrence of macrophages in the retina and periretinal tissues and to determine whether they can be distinguished from migrated cells of the retinal pigment epithelium (RPE). Eyes with proliferative diseases and intraocular melanomas were found to contain more macrophages in the retina than those with uveitis and glaucoma. The epiretinal membranes and subretinal space in eyes of the former group often exhibited additional clustered macrophages and migrated RPE cells. In all specimens studied, RPE cells reacted with antibodies KL-1, CK7, CK18, or CK19 but not with the CD68, Ki-M1P, or lysozyme antibodies. Control eyes without any known disease also contained rare macrophages in the retina. In conclusion, macrophages are regular and normal constituents of the retina that can be clearly distinguished immunohistochemically from migrated RPE cells. Their frequency varies depending on the type of ocular disease involved.

[Ocular tissue after intravitreous silicone oil injection. Histologic and electron microscopy studies]. / Okulare Gewebe nach intravitrealer Silikonölinjektion. Histologische und elektronenmikroskopische Untersuchungen.

The intraocular tolerance of silicone oil is still a matter of ongoing controversy. To evaluate a possible migration of silicone oil into eye tissues we examined various tissues from eyes that were injected with silicone oil for a period of 6 months to 3.5 years. The histological and ultrastructural characteristics of these tissues are reported (cornea, 4 cases; iris, 3 cases; retina, 8 cases; retinal pigment epithelium and optic nerve, 1 case). In the iris and in corneas showing a perforating injury light microscopy revealed vacuoles presumably lying in the cytoplasm of macrophages. Using immunohistochemistry and electron microscopy, macrophages could also be found in the retina of eyes that had been filled with silicone oil for longer than 6 months. Using energy dispersive X-ray analysis, vacuoles could be identified as storage sites of the silicone oil. This observation demonstrates that a long-term silicone oil tamponade may cause a migration of silicone oil into the retina and other ocular tissues. In order to prevent this complication, removal of silicone oil should be performed as early as possible.

Bilateral severe keratomalacia after acute pancreatitis.

A rare bilateral severe keratomalacia occurred in an emaciated alcoholic, 57-year-old white man with acute necrotic pancreatitis. The patient had a 10-year history of chronic alcoholism. Laboratory and clinical findings were consistent with the diagnosis of a fat malabsorptive and malnutrition syndrome secondary to chronic and acute alcoholic pancreatitis. Visual acuity of both eyes was limited to light perception. Bilateral corneal necrosis after acute pancreatitis has not previously been reported.

Biocompatibility of silicone oil and high-density liquids. An immunologic study.

Silicone oil and high-density liquids can be useful tools in the treatment of complicated retinal detachments. To test whether these substances induce specific and/or unspecific inflammatory responses, we performed immunoassays on 60 rats of two different inbred strains. After sensitization, each rat was injected in the right foot pad with either silicone oil, fluorosilicone oil, perfluorooctane, or perfluoropolyether. Depending on the inbred strain, the volume of the foot pads increased up to the fifth day, indicating an injection-induced inflammatory reaction. Histopathological examination of rats injected with silicone oil showed infiltration by mononuclear cells and occasional giant cells. In rats receiving fluorosilicone oil, additional eosinophilic reactions were observed. The most pronounced reactions occurred after injection of the two perfluorocarbons, which induced a greater number of giant cells and a slight granulomatous reaction. The degree of tissue response was independent of the type of sensitization; the majority of the draining popliteal lymph nodes showed no enlargement. Our findings demonstrate that all substances tested induced inflammatory though unspecific responses.

Identification of silicone oil in the retina after intravitreal injection.

Retinal tissue obtained from 2 eyes that had been injected with silicone oil for 2 years was stained with monoclonal antibodies against macrophages and studied by light and electron microscopy and energy-dispersive x-ray analysis. Both specimens showed areas with a relatively intact architecture as well as parts with loss of normal structure. In both areas, immunostaining showed single intraretinal macrophages. Energy-dispersive x-ray results clearly demonstrated that some of the intracellular and extracellular vacuoles within the retina represented the storage sites of silicone.

Experimental intraocular tolerance to liquid perfluorooctane and perfluoropolyether.

Three kinds of perfluorinated liquids (a perfluorooctane and two perfluoropolyethers) were evaluated as vitreous replacements. Tolerance to these liquids in rabbit eyes was investigated for periods of up to 2 months. Clinically, droplet formation of the liquids occurred within a few days of intravitreal injection. Histologic examination revealed no pathologic retinal changes 8 hours after surgery. At 6 days after surgery, hypertrophy of the Müller cells with bumplike protrusions into the interphotoreceptor space could be observed. At 1 month after surgery, light and electron microscopic examination showed larger droplike protrusions of Müller cells related to localized foldings of the outer retinal layers and rarefication of photoreceptor nuclei and loss of outer segments. Frequently disarranged, granule-loaded macrophages appeared in these areas. At 2 months after surgery, vesicles with low electron density appeared in some areas at the border between receptors and retinal pigment epithelium. In other areas pigment epithelial cells showed distinct hypertrophy (with drusen) toward the droplike Müller cell protrusion, together with narrowing of the interreceptor space. These findings were almost totally confined to the lower part of the retina that had been in permanent contact with the liquids. No histologic differences were noted between perfluorooctane- and perfluoropolyether-injected eyes. The results suggest that the liquids are not candidates for long-term vitreous replacement, but may be suitable for short-term intraoperative use.

[Immunohistochemical findings of epiretinal membranes after silicone oil injection]. / Immunhistochemische Befunde von epiretinalen Membranen nach Silikonölinjektion.

During vitreoretinal surgery, 23 epiretinal membranes from eyes treated with silicone oil were removed. They were examined by immunohistochemical methods and compared with 15 membranes from eyes affected by proliferative vitreoretinopathy (PVR) and not treated with silicone oil and with 4 membranes from eyes with intermediate uveitis. PVR membranes from eyes treated with silicone oil showed a high level of macrophages and a strong expression of HLA-DR. Additionally, lymphocytes were found in PVR membranes, a finding that has not been described before. Similar changes were seen in proliferations removed from eyes affected by uveitis, but these membranes were found to have smaller amounts of extracellular substance. In contrast to this, most cells in the PVR membranes from eyes not treated with silicone oil react with vimentin, GFAP and cytokeratin. In none of these membranes were we able to find T-lymphocytes. It is not possible to say whether or not the different findings are attributable ot the silicone oil.