Sox9 marks limbal stem cells and is required for asymmetric cell fate switch in the corneal epithelium

Adult tissues with high cellular turnover require a balance between stem cell renewal and differentiation, yet the mechanisms underlying this equilibrium are unclear. The cornea exhibits a polarized lateral flow of progenitors from the peripheral stem cell niche to the center; attributed to differences in cellular fate. To identify genes that are critical for regulating the asymmetric fates of limbal stem cells and their transient amplified progeny in the central cornea, we utilized an in vivo cell cycle reporter to isolate proliferating basal cells across the anterior ocular surface epithelium and performed single-cell transcriptional analysis. This strategy greatly increased the resolution and revealed distinct basal cell identities with unique expression profiles of structural genes and transcription factors. We focused on Sox9; a transcription factor implicated in stem cell regulation across various organs. Sox9 was found to be differentially expressed between limbal stem cells and their progeny in the central corneal. Lineage tracing analysis confirmed that Sox9 marks long-lived limbal stem cells and conditional deletion led to abnormal differentiation and squamous metaplasia in the central cornea. These data suggest a requirement for Sox9 for the switch to asymmetric fate and commitment toward differentiation, as transient cells exit the limbal niche. By inhibiting terminal differentiation of corneal progenitors and forcing them into perpetual symmetric divisions, we replicated the Sox9 loss-of-function phenotype. Our findings reveal an essential role for Sox9 for the spatial regulation of asymmetric fate in the corneal epithelium that is required to sustain tissue homeostasis.

Taste arbor structural variability analyzed across taste regions

Taste ganglion neurons are functionally and molecularly diverse, but until recently morphological diversity was completely unexplored. Specifically, taste arbors (the portion of the neuron within the taste bud) vary in structure, but the reason for this variability is unclear. Here, we analyzed structural variability in taste arbors to determine which factors determine their morphological diversity. To characterize arbor morphology and its relationship to taste bud cells capable of transducing taste stimuli (taste-transducing cell) number and type, we utilized sparse cell genetic labeling of taste ganglion neurons in combination with whole-mount immunohistochemistry. Reconstruction of 151 taste arbors revealed variation in arbor size, complexity, and symmetry. Overall, taste arbors exist on a continuum of complexity, cannot be categorized into discrete morphological groups, and do not have stereotyped endings. Arbor size/complexity was not related to the size of the taste bud in which it was located or the type of taste-transducing cell contacted (membranes within 180 nm). Instead, arbors could be broadly categorized into three groups: large asymmetrical arbors contacting many taste-transducing cells, small symmetrical arbors contacting one or two taste-transducing cells, and unbranched arbors. Neurons with multiple arbors had arbors in more than one of these categories, indicating that this variability is not an intrinsic feature of neuron type. Instead, we speculate that arbor structure is determined primarily by nerve fiber remodeling in response to cell turnover and that large asymmetrical arbors represent a particularly plastic state.

Colonic immune cells in irritable bowel syndrome: A systematic review and meta-analysis

BACKGROUND & AIMS

Increases in mucosal immune cells have frequently been observed in irritable bowel syndrome (IBS) patients. However, this finding is not completely consistent between studies, possibly due to a combination of methodological variability, population differences and small sample sizes. We performed a meta-analysis of case-control studies that compared immune cell counts in colonic biopsies of IBS patients and controls.

METHODS

PubMed and Embase were searched in February 2017. Results were pooled using standardized mean difference (SMD) and were considered significant when zero was not within the 95% confidence interval (CI). Heterogeneity was assessed based on I² statistics where I²  ≤ 50% and I²  > 50% indicated fixed and random effect models, respectively.

KEY RESULTS

Twenty-two studies on 706 IBS patients and 401 controls were included. Mast cells were increased in the rectosigmoid (SMD: 0.38 [95% CI: 0.06-0.71]; P = .02) and descending colon (SMD: 1.69 [95% CI: 0.65-2.73]; P = .001) of IBS patients. Increased mast cells were observed in both constipation (IBS-C) and diarrhea predominant IBS (IBS-D). CD3⁺ T cells were increased in the rectosigmoid (SMD: 0.53 [95% CI: 0.21-0.85]; P = .001) and the descending colon of the IBS patients (SMD: 0.79, 95% CI [0.28-1.30]; P = .002). This was possibly in relation to higher CD4⁺ T cells in IBS (SMD: 0.33 [95% CI: 0.01-0.65]; P = .04) as there were no differences in CD8⁺ T cells.

CONCLUSIONS & INFERENCES

Mast cells and CD3⁺ T cells are increased in colonic biopsies of patients with IBS vs non-inflamed controls. These changes are segmental and sometimes IBS-subtype dependent. The diagnostic value of the quantification of colonic mucosal cells in IBS requires further investigation.

The unsaponifiable fraction of extra virgin olive oil promotes apoptosis and attenuates activation and homing properties of T cells from patients with inflammatory bowel disease

The unsaponifiable fraction (UF) of extra virgin olive oil (EVOO) possesses anti-inflammatory properties and exerts preventative effects in murine models of inflammatory bowel disease (IBD). The present study was designed to determine the in vitro effects of UF on blood and intestinal T cells from IBD patients and healthy subjects. The T cell phenotype was investigated by flow cytometry and cytokine secretion was determined by ELISA. The presence of UF of EVOO promoted apoptosis and attenuated activation of intestinal and blood T cells isolated from IBD patients, decreasing the frequency of CD69(+) and CD25(+) T cells and, also, the secretion of IFN-γ. Moreover, UF reduced the expression of the gut homing receptor integrin β7 on blood T cells from IBD patients. In conclusion, UF modulates the activity and the gut homing capacity of T cells, and might therefore be considered as a dietary complement with an anti-inflammatory role in IBD patients.

Characterization of IBS-like symptoms in patients with ulcerative colitis in clinical remission

BACKGROUND

Gastrointestinal symptoms compatible with Irritable Bowel Syndrome (IBS) are common in patients with inflammatory bowel disease. It has been suggested that these symptoms are a reflection of occult inflammation rather than coexisting IBS. The aim of this study was to characterize IBS-like symptoms in patients with Ulcerative Colitis (UC) in clinical remission by assessing inflammatory markers, psychological symptoms, and quality of life.

METHODS

Ninety-four patients with new onset of UC were followed prospectively during 3 years with yearly follow-up visits. The patients completed self-administrated questionnaires. Fecal calprotectin was used as an inflammatory biomarker. Remission was defined as a total Mayo-score ≤2 and an endoscopic subscore ≤1, with no relapse during the 3-month period prior to visit.

KEY RESULTS

The prevalence of patients that fulfilled Rome II criteria for IBS among UC patients in remission was 11% at visit 1, 23% at visit 2, and 17% at visit 3. When comparing UC patients in remission with and without IBS-like symptom, patients with IBS-like symptoms had more severe gastrointestinal symptoms, tendencies toward more severe psychological symptoms and reduced levels of quality of life, but the calprotectin levels did not differ between the two groups.

CONCLUSIONS & INFERENCES

IBS-like symptoms are common in patients with UC in clinical remission and these fluctuate over time. The symptoms are associated with poor psychological well-being and reduced quality of life, and do not seem to be a reflection of low-grade inflammatory activity.

Clinical trial: the effects of a fermented milk containing three probiotic bacteria in patients with irritable bowel syndrome - a randomized, double-blind, controlled study

BACKGROUND

The effects of probiotic bacteria in IBS remain controversial.

AIM

To study the effects of a probiotic product on IBS symptoms.

METHODS

We randomized 74 IBS patients to receive 8 weeks of daily treatment with 400 mL milk fermented with the yoghurt bacteria and containing Lactobacillus paracasei, ssp. paracasei F19, Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 (Cultura; active) or acidified milk without these bacteria (control). The primary endpoint was the proportion of subjects reporting adequate relief of their IBS symptoms at least 50% of the weeks. IBS symptom severity, psychological symptoms and quality of life were assessed.

RESULTS

The proportion of responders was 38% (14/37 patients) in the active group and 27% (10/37 patients) in the control group (P = 0.3). IBS symptom severity improved significantly in both groups during the treatment period. This change was greater in the active group during the first 2 weeks, but thereafter, no significant group differences were seen.

CONCLUSIONS

We could not detect a clearly positive effect of fermented milk containing three probiotic bacteria on GI symptoms in IBS patients compared with the control treatment. However, a trend towards a more favourable effect during the first weeks was seen in the active group.

Indirect evidence for increased mechanosensitivity of jejunal secretomotor neurones in patients with idiopathic bile acid malabsorption

AIM

The interdigestive motor rhythm, the migrating motor complex (MMC), is accompanied by active secretion of chloride during periods of distally propagating maximal motor activity (MMC phase III). We studied the behaviour of this system in bile acid malabsorption (BAM), a relative common cause of chronic diarrhoea. We measured motor activity and transmucosal potential difference (PD, reflecting active chloride secretion), in the proximal jejunum in healthy controls (n = 18) and in a group of patients with BAM (n = 11). The phase III-generated voltage was related to the degree of BAM quantified by the (75)SeHCAT test.

METHODS

We used a multi-channel intestinal infusion system to simultaneously measure jejunal pressure and PD. Saline passing calomel half-cells was infused into the jejunum and subcutaneously. Pressure and PD were recorded in the fasting state and after a test meal.

RESULTS

In the absence of motor activity, jejunal PD was not significantly different from zero in either group. During MMC phase III, PD reached significantly higher mean and peak levels in BAM patients. The product of MMC phase III length multiplied by voltage, over 3 h, was also significantly higher in BAM patients (controls: median 307 mV x cm, range 70-398; BAM: median 511, range 274-2271, P < 0.01). This value was also significantly correlated with the degree of BAM as reflected by the (75)SeHCAT test (P < 0.05).

CONCLUSION

Phase III induced jejunal secretion may be upregulated in BAM patients, resulting in overload of colonic reabsorption capacity.

B-cell activation in patients with irritable bowel syndrome (IBS)

Patients with irritable bowel syndrome (IBS) may have a low grade immune activation. However, little is known about the properties of B cells of IBS patients. We therefore investigated activation level and antigen presenting phenotype of blood B cells of IBS patients. We also examined B-cell responses to lipopolysaccharide (LPS) and probiotic bacteria. Blood samples were obtained from 74 IBS patients and 30 healthy subjects. Peripheral blood mononuclear cells were isolated and stimulated with LPS or an UV-light inactivated bacterial cocktail consisting of the probiotic Gram-positive strains; Lactobacillus paracasei ssp. paracasei 19, Lactobacillus acidophilus La5, Bifidobacterium lactis B612. The phenotype of CD19(+) B cells was investigated by flow cytometry before and after 72 h cell culture. Furthermore, IBS symptom severity was assessed. B cells isolated from blood of IBS patients displayed an amplified activation level as demonstrated by increased cell surface expression of IgG, and also the costimulatory molecules CD80 and CD86. Expression of antigen presenting HLA-DR and costimulatory molecule CD40 on B cells was, however comparable in IBS patients and controls. B cells of IBS patients displayed an impaired ability to increase expression of CD80, but not CD86, in response to both LPS as well as probiotic bacteria stimulations. To conclude, blood B cells of IBS patients have an increased activation level. Bacterial component induced expression of the costimulatory molecule CD80, regarded as important for tolerance induction, is impaired. These data suggest that B-cell antigen presentation in IBS patients is associated with altered capacity of providing costimulation to T cells.

Characterization of coagulase-negative staphylococci isolated from patients with infected hip prostheses: use of phenotypic and genotypic analyses, including tests for the presence of the ica operon

The aim of this study was to investigate phenotypic and/or genotypic heterogeneity in coagulase-negative staphylococci (CoNS) obtained from multiple tissue samples taken perioperatively during exchange surgery from each of 19 patients with clinically and/or microbiologically proven hip prosthesis infections. CoNS are important pathogens in prosthetic hip joint infections. Several virulence factors have been suggested for CoNS, such as phenotypic variation, yet the pathogenic processes that are involved remain unclear. The PhenePlate system (PhPlate AB, Stockholm Sweden) was used for phenotyping and pulsed-field gel electrophoresis for genotyping of polymorphisms in isolates of CoNS. Furthermore, polymerase chain reaction was used to determine the presence of the icaADB gene complex in the isolates. Some patients were infected with CoNS and other species, some were infected with multiple CoNS species, although infections with Staphylococcus epidermidis alone were most common, and some were infected with different S. epidermidis clones. Phenotypic variation was found among isolates both from the same tissue sample and from different samples from the same patient, and in some cases such variation represented the presence of different clones. One-third of the patients infected with S. epidermidis carried the icaADB genes. CoNS isolates showing phenotypic and/or genotypic heterogeneity were identified in tissue samples from half of the patients. The presence of the intercellular adhesion (ica) operon does not seem to be a prerequisite for establishing infection with CoNS.

New insights into the pathogenesis and pathophysiology of irritable bowel syndrome

The pathogenesis and pathophysiology of irritable bowel syndrome is complex and still incompletely known. Potential pathogenetic factors include genes, infectious events, psychological symptoms and other loosely defined environmental factors. Both alterations at the central and peripheral level are thought to contribute to the symptoms of irritable bowel syndrome, including psychosocial factors, abnormal gastrointestinal motility and secretion, and visceral hypersensitivity. Today irritable bowel syndrome is viewed upon as a disorder of dysregulation of the so-called brain-gut axis, involving abnormal function in the enteric, autonomic and/or central nervous systems, with peripheral abnormalities probably dominating in some patients and disturbed central processing of signals from the periphery in others. Lines of evidence also suggest that inflammation within the gastrointestinal tract may be of great importance in at least subgroups of irritable bowel syndrome patients. To conclude, a complex picture of the pathogenesis and pathophysiology of irritable bowel syndrome is emerging, with interactions between several different alterations resulting in the divergent symptom pattern in these patients.

CD4+CD25+ regulatory T cells in irritable bowel syndrome patients

The aetiology of the irritable bowel syndrome (IBS) is incompletely understood. A low-grade colonic inflammation is frequently seen, but it is unclear to what extent this phenomenon contributes to the pathophysiology of IBS. CD4(+)CD25(+) regulatory T cells (Treg) are implicated to play an important role in suppressing intestinal inflammation. We, therefore, examined whether the intestinal inflammatory process in IBS patients is the result of an altered function and/or frequency of CD25(+) Treg cells. Patients with IBS (n = 34), fulfilling the Rome II criteria, were compared with controls (n = 26). The suppressive activity of blood CD25(+) Treg cells was determined and the frequency of colonic and blood CD25(+) Treg cells was analysed by flow cytometry. The expression of the Treg marker, FOXP3 mRNA, in colonic biopsies was determined by reverse transcription-polymerase chain reaction. Blood CD25(+) Treg cells from IBS patients suppressed the proliferation of blood CD4(+)CD25(low/-) T cells. Similar frequencies of CD25(+) Treg cells were recorded in mucosa and blood of IBS patients and controls. FOXP3 mRNA was equally expressed in the colonic mucosa of patients with IBS and controls. In conclusion, the low-grade intestinal inflammation recorded in patients with IBS is not associated with an altered function or frequency of CD25(+) Treg cells.

Acellular Bordetella pertussis vaccine enhances mucosal interleukin-10 production, induces apoptosis of activated Th1 cells and attenuates colitis in Galphai2-deficient mice

Mice deficient for the inhibitory G protein subunit alpha2 (Galphai2(-/-)) spontaneously develop a progressive inflammatory bowel disease resembling ulcerative colitis, and have a T helper 1 (Th1)-dominated immune response prior to onset of colitis, which is further augmented after the onset of disease. The present study was performed to investigate whether the Galphai2(-/-) mice were able to down-regulate the Th1-dominated inflammatory mucosal immune response and/or induce an anti-inflammatory Th2/T regulatory response and thereby diminish the severity of colitis following treatment with acellular Bordetella pertussis vaccine. The acellular vaccine against B. pertussis, the causative agent of whooping cough, has been demonstrated to induce a Th2-mediated response in both man and mice. We therefore treated Galphai2(-/-) mice intraperitoneally with a three-component acellular B. pertussis vaccine. The treated Galphai2(-/-) mice showed significantly increased interleukin (IL)-10 production in intestinal tissue, associated with significantly reduced colitis and decreased mortality, compared to untreated Galphai2(-/-) mice. The attenuation of colitis in Galphai2(-/-) mice was due, at least partly, to the B. pertussis surface antigen filamentous haemagglutinin (FHA), which almost completely inhibited proliferation of CD4(+) T cells and stimulated apoptosis of activated CD4(+) T helper 1 cells. In conclusion, the three-component acellular B. pertussis vaccine containing filamentous haemagglutinin increases the production of IL-10 in the intestinal mucosa, induces apoptosis of activated Th1 cells and attenuates colitis in Galphai2(-/-) mice.

A clone of coagulase-negative staphylococci among patients with post-cardiac surgery infections

Coagulase-negative staphylococci (CoNS) are important causes of hospital-acquired infections such as infections after cardiac surgery. Efforts to reduce these infections are hampered by the lack of knowledge concerning the epidemiology of CoNS in this setting. Forty strains of CoNS collected during the surgical revision of 27 patients operated on between 1997 and 2000 were analysed. Strains were also collected from the ambient air in the operating suite. Their pulsed-field gel electrophoresis (PFGE) characteristics and antibiotic resistance were analysed. Using PFGE 19 of 40 strains from 15 of 27 patients were shown to belong to one clone, and strains from this clone were also isolated from the ambient air. This clone had caused infections throughout the period. Antibiotic resistance did not correlate with PFGE patterns. Using PFGE one clone could be identified that caused 56% of the CoNS infections during this period. A strain from this clone was also found in the air of the operating suite suggesting the origin of the CoNS causing infections was the hospital environment.

Regression of Peyer's patches in G alpha i2 deficient mice prior to colitis is associated with reduced expression of Bcl-2 and increased apoptosis

BACKGROUND

G protein deficient (G alpha i2-/-) mice spontaneously develop an inflammatory bowel disease (IBD) closely resembling ulcerative colitis. Previous studies have demonstrated that gut T cells are hyperreactive to the endogenous microflora in most IBD models.

AIMS

The aim of this study was to analyse Peyer's patches (PP), the inductive sites for gut mucosal immune responses.

SUBJECTS AND METHODS

G alpha i2-/- mice, an animal model for IBD, were analysed using immunological methods with regard to phenotype and function.

RESULTS

We found significantly decreased numbers of PP in G alpha i2-/- mice. Even before the onset of colitis, G alpha i2 deficient animals exhibited diminished size of PP, as judged by histology. This involution of PP was associated with strongly increased levels of apoptotic lymphocytes, associated with decreased levels of antiapoptotic intracellular protein Bcl-2. PP T lymphocytes showed highly elevated production of interferon gamma in response to the enteric flora compared with PP T cells from wild-type mice, which produced predominantly interleukin 10.

CONCLUSIONS

Thus even before the onset of colitis, the PP in G alpha i2 deficient mice is a Th1 dominated milieu associated with downregulated levels of Bcl-2, resulting in increased apoptosis of lymphocytes leading to regression of PP. We speculate that this Th1 dominated microenvironment in the inductive site for mucosal immune responses contributes to the development of colitis in G alpha i2 deficient mice.

Changes in the appearance and treatment of deep sternal infections

The Department of Thoracic Surgery at the University Hospital, Linköping, Sweden, has actively followed up infectious complications of cardiac surgery since 1989. The aim of this study was to investigate whether changes occurred during the 1990s in the appearance and the management of deep infections. This was done by studying patients undergoing surgical revision of infected wounds. We studied 42 patients during 1990-94 and 49 during 1997-98 (total number of operations in these periods, 3075 and 1646, respectively). Pre-operative and intra-operative variables were recorded for the two patient populations. The proportion of cardiac surgery procedures followed by a surgical revision for an infection in the sternal wound increased between the two periods (1.4% vs. 3.0%). Variables associated with the surgical procedures preceding the infection remained unchanged. In the later period, treatment was started earlier (64 vs. 24 days), and the length of antibiotic treatment was decreased (115 vs. 72 days). The incidence of osteomyelitis of the sternal bone was lower (61% vs. 27%). It appears that as the proportion of patients undergoing surgical revision increased, management of the infections became more effective, with aggressive surgical and antibiotic treatment policies and shorter treatment periods. This indicates that in order to evaluate the overall impact of measures designed to reduce infections after cardiac surgery, not only the incidence of infection needs to be followed up but other factors also need to be taken into account.

Interaction of Staphylococcus epidermidis from infected hip prostheses with neutrophil granulocytes

This study focuses on the interaction of Staphylococcus epidermidis isolated from granulation tissue covering infected hip prostheses and neutrophil granulocytes. Bacterial strains isolated from normal flora were used as controls. The bacteria were well characterized with routine methods and further characterized with random amplified polymorphic DNA analyses and slime tests. Phagocytosis and chemiluminescence (CL) assays were used in the neutrophil interaction studies. The prostheses strains were ingested to a lesser extent than strains from normal flora (p < or = 0.001). There was no significant difference between the prostheses strains and the normal flora strains in terms of total CL response. However, the extracellular CL response from the neutrophils was lower in comparison with the normal flora when interacting with the prostheses strains. The results of this study support the notion that S. epidermidis strains isolated from infected hip prostheses have an enhanced capacity to resist phagocytosis and that most of these strains elicit a reduced inflammatory response, measured as the production of extracellular oxidative metabolites from the neutrophils, compared to normal flora.

Cell cycle progression in serum-free cultures of Sf9 insect cells: modulation by conditioned medium factors and implications for proliferation and productivity

Cell cycle progression was studied in serum-free batch cultures of Spodoptera frugiperda (Sf9) insect cells, and the implications for proliferation and productivity were investigated. Cell cycle dynamics in KBM10 serum-free medium was characterized by an accumulation of 50-70% of the cells in the G(2)/M phase of the cell cycle during the first 24 h after inoculation. Following the cell cycle arrest, the cell population was redistributed into G(1) and in particular into the S phase. Maximum rate of proliferation (micro(N, max)) was reached 24-48 h after the release from cell cycle arrest, coinciding with a minimum distribution of cells in the G(2)/M phase. The following declining micro(N) could be explained by a slow increase in the G(2)/M cell population. However, at approximately 100 h, an abrupt increase in the amount of G(2)/M cells occurred. This switch occurred at about the same time point and cell density, irrespective of medium composition and maximum cell density. An octaploid population evolved from G(2)/M arrested cells, showing the occurrence of endoreplication in this cell line. In addition, conditioned medium factor(s) were found to increase micro(N,max), decrease the time to reach micro(N,max), and decrease the synchronization of cells in G(2)/M during the lag and growth phase. A conditioned medium factor appears to be a small peptide. On basis of these results we suggest that the observed cell cycle dynamics is the result of autoregulatory events occurring at key points during the course of a culture, and that entry into mitosis is the target for regulation. Infecting the Sf9 cells with recombinant baculovirus resulted in a linear increase in volumetric productivity of beta-galactosidase up to 68-75 h of culture. Beyond this point almost no product was formed. Medium renewal at the time of infection could only partly restore the lost hypertrophy and product yield of cultures infected after the transition point. The critical time of infection correlated to the time when the mean population cell volume had attained a minimum, and this occurred 24 h before the switch into the G(2)/M phase. We suggest that the cell density dependent decrease in productivity ultimately depends on the autoregulatory events leading to G(2)/M cell cycle arrest.

Immune activation in the intestinal mucosa before the onset of colitis in Galphai2-deficient mice

G-protein subunit Galphai2-deficient mice spontaneously develop an inflammatory bowel disease that clinically and histopathologically resembles ulcerative colitis in humans. The aim of this study was to determine whether immunological changes precede the development of colitis in Galphai2-deficient mice. Therefore, Galphai2-deficient mice with no clinical or histopathological signs of colitis were compared with Galphai2-deficient mice with established colitis and wild-type animals, concerning immunological parameters. Healthy Galphai2-deficient mice displayed an increased frequency of CD4+ T cells and a decreased frequency of CD19+ B lymphocytes in the intestinal mucosa compared with control mice. The CD4+ population was characterized by a memory phenotype, i.e. increased expression of CD44 and decreased expression of CD45RB and CD62L, as well as increased expression of the mucosal homing receptors integrins alpha4beta7 and alphaEbeta7. Production of pro-inflammatory cytokines, interleukin (IL)-1beta and interferon (IFN)-gamma, were increased in Galphai2-deficient mice before clinical signs of disease were evident. In addition, total immunoglobulin (Ig)G and IgA levels in large intestinal secretions were increased significantly compared with wild-type mice, and antibodies specific for the normal intestinal flora in large intestinal secretions were present in Galphai2-deficient mice several weeks before the onset of colitis. In contrast, antibodies against tropomyosin, a putative autoantigen in human ulcerative colitis, were not found in Galphai2-deficient mice before the onset of colitis, although they were present in animals with established disease. In conclusion, activation of the intestinal immune system precedes histopathological and clinical signs of inflammation in Galphai2-deficient mice, suggesting that immune abnormalities play an important role in the induction of colitis.

Coagulase-negative staphylococci and sternal infections after cardiac operation

BACKGROUND

Coagulase negative staphylococci (CoNS) have been recognized as important pathogens in nosocomial infections, especially in connection with implanted foreign materials. In cardiac operation they are among the most common pathogens isolated from infected sternal wounds. The definition of the infection is very important. In this study we focus on deep postoperative chest infections.

METHODS

By studying 33 infected patients retrospectively and comparing them to 33 matched uninfected controls, we studied the characteristics and costs of the infections.

RESULTS

Typical for these infections is the late and insidious onset, and that the infections initially give only minor symptoms such as pain, redness, and serous secretion. We found the following risk factors for infection: number of preoperative days in a hospital, the total length of the operation, and if the patient had undergone an early reoperation due to causes other than infection. This kind of infection more than doubled the hospital costs for the patients affected.

CONCLUSIONS

Coagulase negative staphylococci are the most important pathogens in deep postoperative infections in this material. They cause infections that are difficult to recognize since they give only discrete symptoms and start well after the patients leave the hospital. The risk factors for patients with CoNS infections are mostly associated with a long exposure to the hospital environment. The treatment is often difficult and costly because of multiresistant bacteria and frequent need for repeated surgical revisions.

Pathways of glutamine metabolism in Spodoptera frugiperda (Sf9) insect cells: evidence for the presence of the nitrogen assimilation system, and a metabolic switch by 1H/15N NMR

1H/15N and 13C NMR were used to investigate metabolism in Spodoptera frugiperda (Sf9) cells. Labelled substrates ([2-15N]glutamine, [5-15N]glutamine, [2-15N]glutamate, 15NH4Cl, [2-15N]alanine, and [1-13C]glucose) were added to batch cultures and the concentration of labelled excreted metabolites (alanine, NH4+, glutamine, glycerol, and lactate) were quantified. Cultures with excess glucose and glutamine produce alanine as the main metabolic by-product while no ammonium ions are released. 1H/15N NMR data showed that both the amide and amine-nitrogen of glutamine was incorporated into alanine in these cultures. The amide-nitrogen of glutamine was not transferred to the amine-position in glutamate (for further transamination to alanine) via free NH4+ but directly via an azaserine inhibitable amido-transfer reaction. In glutamine-free media 15NH4+ was consumed and incorporated into alanine. 15NH4+ was also incorporated into the amide-position of glutamine synthesised by the cells. These data suggest that the nitrogen assimilation system, glutamine synthetase/glutamate synthase (NADH-GOGAT), is active in glutamine-deprived cells. In cultures devoid of glucose, ammonium is the main metabolic by-product while no alanine is formed. The ammonium ions stem both from the amide and amine-nitrogen of glutamine, most likely via glutaminase and glutamate dehydrogenase. 13C NMR revealed that the [1-13C] label from glucose appeared in glycerol, alanine, lactate, and in extracellular glutamine. Labelling data also showed that intermediates of the tricarboxylic acid cycle were recycled to glycolysis and that carbon sources, other than glucose-derived acetylCoA, entered the cycle. Furthermore, Sf9 cell cultures excreted significant amounts glycerol (1.9-3.2 mM) and ethanol (6 mM), thus highlighting the importance of sinks for reducing equivalents in maintaining the cytosolic redox balance.

Autoantibodies against the tumour-associated antigen GA733-2 in patients with colorectal carcinoma

The tumour-associated antigen (TAA) GA733-2 is expressed as a non-secreted surface molecule on the majority of human colorectal carcinoma cells. The antigen has been used as a target for passive and active immunotherapy during the last decade. To determine the incidence of autoantibodies against this antigen, sera from 1068 patients with colorectal carcinoma were analysed for naturally occurring IgG antibodies against the baculovirus-produced GA733-2E protein. A total of 14.5% of the patients had IgG antibodies against the antigen. In 519 patients, sera were collected at the time of diagnosis and 15% of those patients had anti-GA733-2E IgG antibodies. There was a tendency to a higher frequency of patients with antibodies among those in the advanced Dukes stages: 11% in stage A and 32% in stage D respectively (P = 0.06). Antibodies could be detected for up to 10 years after the diagnosis. Patients with Crohn's disease or colitis ulcerosa (n = 20) did not elicit anti-GA733-2E antibodies. No healthy control donor (n = 45) had detectable antibodies against the antigen. The specificity of GA733-2E-reactive serum IgG was indicated by significant inhibition of mAb17-1A (originally used to define GA733-2) binding to the GA733-2E antigen. Sera of positive patients bound to the GA733-2-expressing human colorectal carcinoma cell line, SW948. No significant correlation was found between the presence of antibodies and survival in the present patient population. However, the high incidence of autoantibodies against this tumour antigen in colorectal carcinoma patients confirms its antigenicity in humans and supports the use of the GA733-2 antigen as a target for immunotherapy.

The influence of excimer laser ablation on recurrent corneal erosions: a prospective randomized study

PURPOSE

We sought to evaluate the effect of excimer laser ablation on wound healing in patients with a history of recurrent corneal erosions.

METHODS

In a prospective, randomized study, 56 patients were treated either with epithelial removal only (n = 28) or epithelial removal followed by excimer laser ablation (n = 28). Patients were followed up at 1, 3, 6, and 12 months postoperatively. Visual acuity, refraction, intraocular eye pressure, and patients' symptoms, as well as their degree. were recorded before and after treatment. A recurrent erosion was regarded as a treatment failure. A Summit ExciMed 200 was used for the ablation. The laser was set to a 5-microm ablation by using a 6.5-mm in diameter treatment.

RESULTS

With regard to ocular symptoms and recurrence of corneal erosions, treatment with excimer laser after epithelial removal was significantly better (p < 0.005) than epithelial removal alone on the healing of recurrent corneal erosions. No complications and no change in visual acuity, refraction, or intraocular pressure occurred.

CONCLUSION

The use of excimer laser ablation after epithelial removal improved wound healing in patients with recurrent corneal erosions.

Physiology of cultured animal cells

The physiology of cultured animal cells, in particular hybridoma, myeloma and insect cells, with respect to growth and proliferation, amino acid metabolism, energy metabolism and cellular responses to environmental stress is discussed in this paper. The rate of proliferation of hybridoma cells in serum-containing media is limited by growth factors at a surprisingly early stage of growth. To maintain exponential growth in a batch culture, it is necessary to stimulate cell proliferation with repeated additions of serum or pure growth factor. It is further suggested that proliferation of Spodoptera frugiperda (Sf9 insect cells), a normal cell line able to grow in a serum-free medium without any added growth factors, is regulated by autocrine growth factors and possibly by other regulatory mechanisms, as Sf9 cells secrete a growth factor (IGF-I) and the medium still appears nutritionally sufficient at the time of cessation of growth. The uptake and metabolism of amino acids is one of the determinants of growth and production. Wasteful overproduction of amino acids in myeloma and hybridoma cells is a result of excess glutamine, and can be avoided by glutamine limitation. Synthesis of amino acids may be conditional, as in Sf9 cells which synthesise glutamine provided that ammonium is supplied to the medium; and cysteine (from methionine) provided that a sufficiently young inoculum is used. Uptake of amino acids in Sf9 cells appears regulated in relation to the proliferative status as there is a distinct cessation of uptake even before growth ceases. The energy metabolism in myeloma, hybridoma and insect cells is a typically substrate-concentration-dependent overflow metabolism. Substrate limitation (glucose and glutamine) decreases by-product formation and increases metabolic efficiency in all these cell lines. However, glutamine limitation, as used in fed-batch cultures (or chemostat cultures) provokes cell death (in parallel to growth) in hybridoma cells in the concentration range below 0.05 mM.

Molecular basis of agonism and antagonism in the oestrogen receptor

Oestrogens are involved in the growth, development and homeostasis of a number of tissues. The physiological effects of these steroids are mediated by a ligand-inducible nuclear transcription factor, the oestrogen receptor (ER). Hormone binding to the ligand-binding domain (LBD) of the ER initiates a series of molecular events culminating in the activation or repression of target genes. Transcriptional regulation arises from the direct interaction of the ER with components of the cellular transcription machinery. Here we report the crystal structures of the LBD of ER in complex with the endogenous oestrogen, 17beta-oestradiol, and the selective antagonist raloxifene, at resolutions of 3.1 and 2.6 A, respectively. The structures provide a molecular basis for the distinctive pharmacophore of the ER and its catholic binding properties. Agonist and antagonist bind at the same site within the core of the LBD but demonstrate different binding modes. In addition, each class of ligand induces a distinct conformation in the transactivation domain of the LBD, providing structural evidence of the mechanism of antagonism.

Seven days of euglycemic hyperinsulinemia induces insulin resistance for glucose metabolism but not hypertension, elevated catecholamine levels, or increased sodium retention in conscious normal rats

Epidemiological studies have suggested an association among chronic hyperinsulinemia, insulin resistance, and hypertension. However, the causality of this relationship remains uncertain. In this study, chronically catheterized conscious rats were made hyperinsulinemic for 7 days (approximately 90 mU/l, i.e., threefold over basal), while strict euglycemia was maintained (approximately 130 mg/dl, coefficient of variation < 10%) by using a modification of the insulin/glucose clamp technique. Control rats received vehicle infusion. Baseline mean arterial pressure and heart rate were 125 +/- 5 mmHg and 427 +/- 12 beats/min and remained unchanged during the 7-day infusion of insulin (127 +/- 7 mmHg; 401 +/- 12 beats/min) or vehicle (133 +/- 4 mmHg; 411 +/- 10 beats/min). Baseline plasma epinephrine (88 +/- 15 pg/ml), norepinephrine (205 +/- 31 pg/ml), and sodium balance (0.34 +/- 0.09 mmol) remained constant during the 7-day insulin or vehicle infusion. After 7 days of insulin or vehicle infusion, in vivo insulin action was determined in all rats using a 2-h hyperinsulinemic (1 mU/min) euglycemic clamp with [3-3H]glucose infusion to quantitate whole-body glucose uptake, glycolysis, glucose storage (total glucose uptake minus glycolysis), and hepatic glucose production. Compared with vehicle-treated rats, 7 days of sustained hyperinsulinemia resulted in a reduction (P < 0.01) in insulin-mediated glucose uptake, glucose storage, and glycolysis by 39, 62, and 26%, respectively. Hepatic glucose production was normally suppressed after 7 days of hyperinsulinemia. Neither insulin-stimulated glucose uptake nor glucose storage correlated with blood pressure or heart rate. In conclusion, 7 days of euglycemic hyperinsulinemia induces severe insulin resistance with respect to whole-body glucose metabolism but does not increase blood pressure, catecholamine levels, or sodium retention. This indicates that hyperinsulinemia-induced insulin resistance is not associated with the development of hypertension in rats who do not have a genetic predisposition for hypertension. Because hyperinsulinemia was initiated in normal rats under euglycemic conditions, additional (inherited or acquired) factors may be necessary to observe an effect of hyperinsulinemia and/or insulin resistance to increase blood pressure.

Comparative studies of rat recombinant purple acid phosphatase and bone tartrate-resistant acid phosphatase

The tartrate-resistant acid phosphatase (TRAP) of rat osteoclasts has been shown to exhibit high (85-94%) identity at the amino acid sequence level with the purple acid phosphatase (PAP) from bovine spleen and with pig uteroferrin. These iron-containing purple enzymes contain a binuclear iron centre, with a tyrosinate-to-Fe(III) charge-transfer transition responsible for the purple colour. In the present study, production of rat osteoclast TRAP could be achieved at a level of 4.3 mg/litre of medium using a baculovirus expression system. The enzyme was purified to apparent homogeneity using a combination of cation-exchange, hydrophobic-interaction, lectin-affinity and gel-permeation chromatography steps. The protein as isolated had a purple colour, a specific activity of 428 units/mg of protein and consisted of the single-chain form of molecular mass 34 kDa, with only trace amounts of proteolytically derived subunits. The recombinant enzyme had the ability to dephosphorylate bone matrix phosphoproteins, as previously shown for bone TRAP. Light absorption spectroscopy of the isolated purple enzyme showed a lambda max at 544 nm, which upon reduction with ascorbic acid changed to 515 nm, concomitant with the transition to a pink colour. EPR spectroscopic analysis of the reduced enzyme at 3.6 K revealed a typical mu-hydr(oxo)-bridged mixed-valent Fe(II)Fe(III) signal with g-values at 1.96, 1.74 and 1.60, proving that recombinant rat TRAP belongs to the family of PAPs. To validate the use of recombinant PAP in substituting for the rat bone counterpart in functional studies, various comparative studies were carried out. The enzyme isolated from bone exhibited a lower K(m) for p-nitrophenyl phosphate and was slightly more sensitive to PAP inhibitors such as molybdate, tungstate, arsenate and phosphate. In contrast with the recombinant enzyme, TRAP from bone was isolated predominantly as the proteolytically cleaved, two-subunit, form. Both the recombinant enzyme and rat bone TRAP were shown to be substituted with N-linked oligosaccharides. A slightly higher apparent molecular mass of the monomeric form and N-terminal chain of bone TRAP compared with the recombinant enzyme could not be accounted for by differential N-glycosylation. Despite differences in specific post-translational modifications, the recombinant PAP should be useful in future studies on the properties and regulation of the mammalian PAP enzyme.

Metabolic engineering of animal cells

Substrate-limited fed-batch cultures were used to study growth and overflow metabolism in hybridoma and insect cells. In hybridoma cells a glucose-limited fed-batch culture decreased lactate formation but increased glutamine consumption and ammonium formation. Glutamine limitation decreased ammonium and alanine formation but did not enhance glucose consumption. Instead lactate formation was reduced, indicating that glucose was used more efficiently. The formation of lactate, alanine, and ammonium was negligible in a dual substrate-limited fed-batch culture. The efficiency of the energy metabolism increased, as judged by the increase in the cellular yield coefficient for glucose of 100% and for glutamine of 150% and by the change in the metabolic ratios lac/glc, ala/gln, and NHx/gln, in the combined fed-batch culture. Insect cell metabolism was studied in Spodoptera frugiperda (Sf-9) cells. A stringent relation between glucose excess and alanine formation was found. In contrast, glucose limitation induced ammonium formation, while, at the same time, alanine formation was completely suppressed. Simultaneous glucose and glutamine limitation suppressed both alanine and ammonium formation. Alanine formation appears as wasteful as lactate formation because the growth rate of insect cells in substrate-limited cultures was the same as in batch cultures with substrate excess. In batch and fed-batch cultures of both cell lines, mu reaches it maximum early during growth and decreases thereafter so that no exponential growth occurs. The growth rate limiting factor for hybridoma cells was found to be a component of serum, because intermittent serum additions to batch cultures resulted in a high and constant growth rate. Insulin was identified as the main cause, inasmuch as intermittent insulin additions gave the same result as serum.

Induction of a metabolic switch in insect cells by substrate-limited fed batch cultures

Insect cell metabolism was studied in substrate-limited fed batch cultures of Spodoptera frugiperda (Sf-9) cells. Results from a glucose-limited culture, a glutamine-limited culture, a culture limited in both glucose and glutamine, and a batch culture were compared. A stringent relation between glucose excess and alanine formation was found. In contrast, glucose limitation induced ammonium formation, while, at the same time, alanine formation was completely suppressed. Simultaneous glucose and glucosamine limitation suppressed both alanine and ammonium formation. Although the metabolism was influenced by substrate limitation, the specific growth rate was similar in all cultures. Alanine formation must involve incorporation of free ammonium, if ammonium formation is mediated by glutaminase and glutamate dehydrogenase, as our data suggest. On the basis of the results, two possible pathways for the formation of alanine in the intermediary metabolism are suggested. The cellular yield on glucose was increased 6.6 times during glucose limitation, independently of the cellular yield on glutamine, which was increased 50-100 times during glutamine limitation. The results indicate that alanine overflow metabolism is energetically wasteful and that glutamine is a dispensable amino acid for cultured Sf-9 cells. Preliminary data confirm that glutamine can be synthesized by the cells themselves in amounts sufficient to support growth.

The chemiluminescence response of neutrophils on polymer surfaces made by glow discharge plasma polymerization

Polypropylene tubes were coated with different polymers made by glow discharge plasma polymerization. Isolated human blood neutrophils were allowed to interact with the polymer surface and the chemiluminescence response of the cells was recorded as a measure of oxidative activation. The polymers represented surfaces that differed markedly with respect to charge, hardness, and wettability. We found that all polymers stimulated the chemiluminescence response in neutrophils differently; when preincubation with human serum albumin (HSA) there was a general reduction of the chemiluminescence response particularly on one of the positively charged surface 1,2-diamino-cyclohexane (DACH). Addition of a soluble stimulus, the chemoattractant formylmethionyl-leucylphenylalanine (FMLP), to the cells caused a dramatic increase in the response on one of the hydrophobic surface hexamethylene-disiloxane (HMDSO). However, there was also a pronounced reduction in the response on polymers with acrylic acid (AA). The response was normalized after addition of HSA. Taken together, the chemiluminescence response of the neutrophils interacting with the polymer surfaces differed with regard to the type of surfaces. When HSA and FMLP were added a larger difference in the response was found. Our results showed that the activation of human neutrophil granulocytes influenced by different polymer surfaces, followed unspecific different patterns which were someway related to the specific characteristics of the polymer and from this point we came to similar conclusions made by Kaplan et al. (J. Biomater. Res. 28, 377 (1994)), that it is difficult to extrapolate any activation mechanisms from one material to another.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between susceptibility of infants to infections and interaction with neutrophils of Escherichia coli strains causing neonatal and infantile septicemia

The ability of Escherichia coli strains causing invasive infections to associate to human neutrophils and induce oxygen radicals was studied in three groups of blood isolates from neonates and infants: low-virulence septicemia strains (LVS), normal septicemia strains (NS), and meningitis strains (M). Infants were classified by susceptibility to infection as low- (LR) or high-risk (HR). All LVS strains were isolated from HR infants and showed higher association to neutrophils (P < .05) and induced a higher oxidative response (P < .05) compared with that of NS and M strains from LR infants. Three LVS strains caused the cells to release oxidative metabolites extracellularly. Thus, impaired interaction with neutrophils is characteristic of virulent clones of E. coli capable of causing invasive infection in healthy full-term neonates. Furthermore, increased extracellular release of oxygen metabolites could harm the surrounding tissue and potentiate the inflammatory process.

Phototherapeutic keratectomy in herpes simplex keratitis. Clinical results in 20 patients

Twenty eyes in 20 patients with herpetic keratitis were treated with excimer laser photoablation. Sixteen eyes underwent phototherapeutic keratectomy because of scars and surface irregularities, with the goal to improve vision and 1 eye for cosmetic reasons. Two eyes had slight scars but were treated because of a refractive error (PRK). One eye had a metaherpetic ulcer where the wound surface was ablated with the intention to improve healing. Twelve of the 16 eyes showed improved visual acuity of 2 lines or more on the Snellen chart. The refractive outcome was acceptable in the 2 PRK eyes. The cosmetic result was good and the metaherpetic wound epithelialized within 3 weeks. Of the 20 patients 5 had 1 or more recurrences during the 16.8 months of follow-up. In the 17 months preceding the laser surgery 9 eyes had 1 or more recurrences. Three of these eyes still showed improved vision. Phototherapeutic excimer laser surgery is advantageous in selected cases and should be considered before corneal grafting. The procedure does not seem to increase the incidence of recurrences.

Treatment of recurrent corneal erosions with the excimer laser

Seventy-six patients with recurrent corneal erosions resistant to conventional therapy with ointment, abrasion or contact lenses were treated with the excimer laser. The patients were treated in 3 different ways; ablation of 3 or 5 microns after epithelial removal, or ablation of 20 microns directly on the epithelium. Twenty out of the 76 treated eyes showed recurrences. Thirty-five of the patients had no symptoms after treatment and 21 patients had minor symptoms. The 3 different treatment modes were equally successful in the present study.

Nebulae at keratoconus--the result after excimer laser removal

Ten patients underwent excimer laser ablation due to nebula formation at keratoconus. The nebulae interfered significantly with contact lens fit or wearing time. The mean follow-up time in these patients was 16.5 months. Following surgery all patients could be successfully fitted with a contact lens and thereby obtain good visual acuity. Furthermore, contact lens wearing time was 8 hours or more in all cases. In 2 patients the nebulae recurred but were successfully retreated.

Phototherapeutic keratectomy: long-term results in 166 eyes

One hundred sixty-six eyes with corneal disease were treated with the excimer laser in order to ablate opacities, irregularities, or to improve wound healing. Postoperative follow up time was 15 months (range 6 to 28 months). An individual goal was set for each patient and 84% achieved the goal. The visual acuity change is given for each subgroup. Phototherapeutic keratectomy (PTK) was shown to be an advantageous surgical method, where the success is in the careful preoperative evaluation. One problem with the technique is the induced hyperopia.

Increased insulin sensitivity in the high sodium one-kidney, one figure-8 hypertensive rat

This study examines the relation between sympathetic activity and in vivo insulin-mediated glucose metabolism in a rat model of acquired hypertension. Two groups of conscious, unrestrained rats were studied in the postabsorptive state: sham-operated normotensive rats (n = 10) and renal-wrapped hypertensive rats (n = 10). Mean arterial pressure was increased in the hypertensive compared with the normotensive group in the fed (184 +/- 9 versus 144 +/- 6 mm Hg; p less than 0.01) and in the fasting (147 +/- 8 versus 112 +/- 7 mm Hg; p less than 0.01) state. After a 24-hour fast, hepatic glucose production, plasma glucose, insulin, and norepinephrine concentrations were similar in the two groups. Blood pressure did not change in either group during the 3-milliunits/kg.min euglycemic insulin clamp study; however, plasma norepinephrine concentration rose significantly in hypertensive (207 +/- 24 versus 329 +/- 11 pg/ml; p less than 0.05) but not in normotensive rats (229 +/- 23 versus 267 +/- 27 pg/ml; p = NS). During the insulin clamp study, the hepatic glucose production was similar in the hypertensive (3.8 +/- 0.8 mg/kg.min) compared with the normotensive (4.0 +/- 0.3 mg/kg.min) rats. Insulin-mediated glucose uptake was significantly higher in hypertensive than in normotensive rats (33.0 +/- 0.7 versus 25.8 +/- 0.8; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

N-acetylcysteine enhances receptor-mediated phagocytosis by human neutrophils

The effect of the sulphur compound N-acetylcysteine (NAC) on certain receptor-mediated cellular functions [chemiluminescence (CL), phagocytosis and degranulation] in human neutrophils was studied, to evaluate how a scavenger of certain toxic oxygen product can protect the phagocyte and the bystander tissue cells from oxidative damage. When using IgG-opsonized yeast particles as stimulating agent, preincubating the neutrophils with NAC (0.25 mg/ml = 1.5 mM) increased both the CL response and phagocytosis. Higher concentrations of NAC (0.50-1.00 mg/ml = 3-6 mM) decreased the CL response, whereas the phagocytic capacity was still enhanced. This effect was more pronounced with adherent neutrophils than with neutrophils in suspension. No increased CL or phagocytic activity was, however, induced by NAC when C3bi-opsonized particles were used as a prey. From the fact that NAC (i) inhibited extracellularly localized myeloperoxidase dependent activities, and (ii) had no effect on neutrophils from patients with chronic granulomatous disease (CGD), we conclude that the scavenger effect of NAC not only reduces the accumulation of oxidative metabolites per se, but also enhances receptor-mediated phagocytosis by protecting Fc(IgG)-receptors from oxidative damage mediated by myeloperoxidase (MPO) and hydrogen peroxide (H2O2). Since NAC can increase phagocytosis and reduce the extracellularly produced oxidative metabolites, we furthermore conclude that NAC possesses some ideal properties as an anti-inflammatory agent.

In vivo insulin action in genetic models of hypertension

Insulin resistance has been described in nonobese subjects with essential hypertension. At present it is unknown whether hypertension per se may lead to the onset of insulin resistance. To examine this question we studied in vivo insulin action in two rat models of genetic hypertension. Four groups of conscious rats were studied: Milan hypertensive (MHS), Milan normotensive (MNS), spontaneously hypertensive (SHR), and Wistar-Kyoto (WKY). Mean arterial pressure was increased in SHR vs. WKY in both the fed (184 +/- 5 vs. 126 +/- 6 mmHg; P less than 0.001) and fasting (160 +/- 5 vs. 129 +/- 5; P less than 0.001) states. During high-dose insulin clamps, total body glucose uptake (mg.kg-1.min-1) was similar in MNS (28.7 +/- 1.4) vs. MHS (33.6 +/- 3.0) and in WKY (34.6 +/- 1.8) vs. SHR (35.7 +/- 2.4). During low-dose insulin clamps, suppression of hepatic glucose production (3.5 +/- 0.6 vs. 3.0 +/- 0.5 mg.kg-1.min-1) and stimulation of glycolysis (12.9 +/- 0.8 vs. 14.4 +/- 1.5 mg.kg-1.min-1) were similar in WKY vs. SHR, whereas glucose uptake (24.6 +/- 1.9 vs. 18.3 +/- 1.2 mg.kg-1.min-1; P less than 0.01) and muscle glycogenic rate (10.2 +/- 1.1 vs. 6.5 +/- 1.1 mg.kg-1.min-1; P less than 0.05) were increased in SHR vs. WKY. In conclusion, 1) feeding markedly augments blood pressure in hypertensive but not in normotensive rats, and 2) hepatic and muscle insulin sensitivity are normal or increased in two different rat models of genetic hypertension. These results provide evidence that high blood pressure per se does not invariably lead to the development of insulin resistance.

Extracellular release of reactive oxygen species from human neutrophils upon interaction with Escherichia coli strains causing renal scarring

The production of reactive oxygen metabolites by neutrophils plays a key role in the host defense against invading microorganisms and in tissue damage resulting from infection. In the present study we measured the ability of different uropathogenic Escherichia coli strains to induce generation of oxygen metabolites upon interaction with human neutrophils. The strains were selected to represent two groups of patients with recurrent episodes of acute pyelonephritis: one with renal scars (12 strains) and one without renal scarring (11 strains). The majority of strains (from both groups) induced a pronounced neutrophil respiratory burst activity. When the intracellular and extracellular oxidative responses were measured separately, it was found that the response induced by nonscarring strains was primarily of intracellular (intraphagosomal) origin, whereas a proportionally larger fraction of the response induced by the scarring strains was extracellular. Since reactive oxygen products are toxic to the renal tissue, this release can be of importance in the development of renal scars.

The melanophore aggregating response of isolated fish scales: a very rapid and sensitive diagnosis of whooping cough

Pertussis toxin (PT) has been found to block noradrenaline-induced pigment aggregation in fish melanophores, and, based on this, a rapid and highly sensitive assay for PT was developed. Some preliminary results have also indicated that it may be possible to detect PT-like activity in saliva samples from patients with clinically suspected pertussis. In the present study the diagnostic value of the fish melanophore method was evaluated in 70 patients suspected of having pertussis; culture, serology and physician diagnosis were used as reference methods. In 60 of the patients, pertussis was verified by at least one of the reference methods. The melanophore test showed PT-like activity in saliva samples from 58 of the patients. Three patients with reference-verified pertussis showed no PT-like activity in the test; among these, one patient had been immunized and had also been treated with erythromycin during 3 days immediately prior to visiting the hospital. The melanophore test has three major advantages: it allows detection of pertussis in the early and curable stage of the disease; it takes only 2 h to perform; and it requires no sophisticated equipment.

Heparin surface modified intraocular lenses--a one-year follow-up of a safety study

PMMA intraocular lenses have been modified by bonding a monolayer of Heparin molecules to the surface. These Heparin surface modified (HSM) IOLs were implanted in the capsular bag after extracapsular cataract extraction. Sixty-six patients were followed for 12 months in an open safety study. No unexpected reactions or severe complications occurred. Eighty-nine per cent of the patients obtained a visual acuity (VA) of 0.5 or more at the 12-month visit. When excluding cases with preoperative pathology only one case (1.5%) had less VA than 0.5. A mild postoperative iritis was seen during the first week after surgery, and in only three cases at a later visit. Cell precipitates were seen in a small number of cases. From this study and from earlier in vitro and in vivo animal studies we draw the conclusion that the Heparin surface modified IOLs are safe for implantation in human eyes.