TGF-β/Extracellular Matrix Interactions in Dentin Matrix: A Role in Regulating Sequestration and Protection of Bioactivity

TGF-β isoforms sequestrated in dentin matrix potentially provide a reservoir of bioactive molecules that may influence cell behavior in the dentin–pulp complex following tissue injury. The association of these growth factors with dentin matrix and the influence of such associations on the bioactivity of growth factors are still unclear. We used surface plasmon resonance technology in the BIAcore^TM 3000 system to investigate the binding of TGF-β isoforms 1 and 3 to purified decorin, biglycan, and EDTA soluble dentin matrix components. TGF-β isoforms 1 and 3 were immobilized on sensorchips CM4 through amine coupling. For kinetic studies of protein binding, purified decorin and biglycan, isolated EDTA soluble dentin matrix, and dentin matrix immunodepleted of decorin and/or biglycan were injected over TGF-β isoforms and allowed to interact. Programmed kinetic analysis software provided sensorgrams for each concentration of proteoglycan or dentin matrix extract injected. Purified decorin and biglycan and dentin matrix extract bound to the TGF-β isoforms. However, the association with TGF-β3 was much weaker than that with TGF-β1. After immunoaffinity depletion of the dentin matrix extract, the level of interaction between the dentin matrix extract and TGF-β was significantly reduced. These results suggest isoform-specific interactions between decorin/biglycan and TGF-β isoforms 1 and 3, which may explain why TGF-β3 is not detected in the dentin matrix despite being expressed at higher levels than TGF-β1 in odontoblasts. These proteoglycans appear to play a significant role in TGF-β/extracellular matrix interactions and may be important in the sequestration of these growth factors in the dentin matrix.     

Pathomechanismen des Organversagens

Proinflammatory mediators as well as increased formation of reactive oxygen and nitrogen species impair cellular respiration during sepsis. In particular, the highly reactive peroxynitrite irreversibly damages lipids, proteins and nucleic acids and also inhibits enzyme complexes of the respiratory chain. In this way cellular metabolic functions and subsequently organ functions are also impaired. Repair of DNA by poly(ADP-ribose)polymerase consumes large amounts of nicotinamide adenine dinucleotide (NAD⁺) which leads to cellular NAD⁺ depletion further promoting inflammation. This article summarizes central aspects of the pathophysiology of mitochondrial dysfunction during sepsis and gives an overview about newly developed strategies which proved effective in experimental studies and may have a potential clinical application in the future.     

Montelukast exerts no acute direct effect on NO synthases

The cysteinyl leukotrienes (CysLTs) LTC(4), LTD(4) and LTE(4) are potent proinflammatory lipid mediators that play a central role in inflammation, contraction and remodelling of airways observed in asthmatics. Montelukast, a competitive inhibitor of the cysteinyl leukotriene-1 (CysLT(1)) receptor attenuates asthmatic airway inflammation, contraction and remodelling. As a number of studies have shown that montelukast reduced exhaled nitric oxide (NO) levels, a marker of inflammation that correlates with the severity of asthma, we investigated whether or not a direct inhibition of NO synthase (NOS) by montelukast takes place. In an ex vivo rat lung perfusion and ventilation model the NOS-dependent vasodilation effect after lipopolysaccharide (LPS) infusion was assessed with and without montelukast. Functional organ bath studies using isolated aortic rings from the same species aimed to assess effects of montelukast on the inducible and endothelial NOS isoenzymes (i- and eNOS) as well as on iNOS expression. Neuronal NOS (nNOS) was assessed by field stimulated rabbit corpus cavernosum, and isolated human iNOS enzyme activity was assessed for potential inhibition. Montelukast failed to cause vasoconstriction in LPS challenged rat lung, or to inhibit i- and eNOS activity as well as iNOS expression in aortic rings from the same species. Also the assays for nNOS in rabbit corpus cavernosum and on isolated human iNOS enzyme gave no evidence for a direct inhibition by montelukast in physiological and supraphysiological concentrations up to 10(-4)M. We therefore conclude that montelukast has no acute NOS inhibitor action. Its effect on exhaled NO is therefore probably indirectly mediated by a modulation of the asthmatic airway inflammation.     

Critical temperature ranges of hypothermia-induced platelet activation: possible implications for cooling patients in cardiac surgery

Cooling of the patient is routinely applied in cardiac surgery to protect organs against ischemia. Hypothermia induces activation of platelets, but the effects of temperatures such as used during cardiac surgery are not well described. To investigate this in an in-vitro study heparinized whole blood was incubated at different temperatures (37 degrees C, 34.5 degrees C, 32 degrees C, 29.5 degrees C, 27 degrees C, 24.5 degrees C, 22 degrees C, 19.5 degrees C and 17 degrees C). The effect of these temperatures on aggregation, P-selectin expression, GP IIb/IIIa activation and platelet microparticle (PMP) formation of unstimulated and ADP-stimulated platelets of 36 subjects was evaluated in flow cytometry. A four-parametric logistic model was fitted to depict the temperature effect on platelet parameters. Lower temperatures increased aggregates, P-selectin expression, and GP IIb/IIIa activation. The number of PMPs decreases with hypothermia. Additional experiments revealed a slight influence of heparin on platelet P-selectin expression but excluded an effect of this anticoagulant on the other evaluated parameters. Threshold temperatures, which mark 5% changes of platelet parameters compared to values at 37 degrees C, were calculated. On ADP-stimulated platelets the thresholds for P-selectin expression and GP IIb/IIa activation are 34.0 degrees C and 36.4 degrees C, respectively, and lie in the temperature range routinely applied in cardiac surgery. Hypothermia-induced platelet activation may develop in most patients undergoing cardiac surgery, possibly resulting in thromboembolic events, coagulation defects, and proinflammatory leukocyte bridging by P-selectin bearing platelets and PMPs. These findings suggest that pharmacological protection of platelets against hypothermia-induced damage may be beneficial during cardiac surgery.     

Atrial natriuretic peptide, a regulator of nuclear factor-kappaB activation in vivo

Natriuretic peptides (NPs) comprise a family of vasoactive hormones that play important roles in the regulation of cardiovascular and renal homeostasis. Along this line, atrial NP (ANP) (international non-proprietary name: carperitide, HANP) is an approved drug for the treatment of acute heart failure. In recent years, evidence has been given that the NP system possesses a far broader biological spectrum than the regulation of blood pressure and volume homeostasis. In fact, a substantial amount of in vitro work indicates that ANP affects important inflammatory processes and signaling pathways. Quite surprisingly, however, no information exists on the in vivo antiinflammatory potential and signaling of ANP. We show here that pretreatment of lipopolysaccharide (Salmonella abortus equi, 2.5 mg/kg)-challenged mice with ANP (5 microg/kg iv, 15 min) rapidly inhibits nuclear factor-kappaB activation via inhibition of phosphorylation and degradation of the IkappaB-alpha protein. ANP also reduces Akt activation upon lipopolysaccharide injection. In ANP-pretreated mice, the increase of TNF-alpha serum concentration is markedly prevented; most importantly, the survival of these animals improved. These findings demonstrate both in vitro and in vivo an antiinflammatory profile of ANP that deserves to be further investigated in a therapeutic perspective.     

Comorbidities play a larger role in predicting health-related quality of life compared to having an ostomy

BACKGROUND: Previous research suggests an ostomy worsens health-related quality of life (HR-QOL), but comorbidities also can affect HR-QOL. METHODS: Eligible patients had abdominal operation with ostomy (cases) or similar procedure without ostomy (controls). Patients were recruited for this case-control study from 3 Veterans Affairs hospital medical and pharmacy records. Comorbidities were assessed with Charlson-Deyo Comorbidity Index. Multinomial logistic regression evaluated the impact of comorbidities and having an ostomy on HR-QOL, measured using the Medical Outcomes Study Short Form 36 for Veterans. RESULTS: A total of 237 ostomates (cases) and 268 controls were studied. Average age was 69 years; 64% of cases had colostomy, 36% ileostomy. Twenty-nine percent of patients had a high level of comorbidities. Cases and controls were similar except for reasons for undergoing surgery. High comorbidity was a significant predictor of low HR-QOL in 6 domains of the Short Form 36 for Veterans; having an ostomy was a significant predictor in 4. CONCLUSIONS: High comorbidity significantly influences low HR-QOL and impacted more domains than having an ostomy.     

Therapeutic suppression of translation initiation modulates chemosensitivity in a mouse lymphoma model

Disablement of cell death programs in cancer cells contributes to drug resistance and in some cases has been associated with altered translational control. As eukaryotic translation initiation factor 4E (eIF4E) cooperates with c-Myc during lymphomagenesis, induces drug resistance, and is a genetic modifier of the rapamycin response, we have investigated the effect of dysregulation of the ribosome recruitment phase of translation initiation on tumor progression and chemosensitivity. eIF4E is a subunit of eIF4F, a complex that stimulates ribosome recruitment during translation initiation by delivering the DEAD-box RNA helicase eIF4A to the 5' end of mRNAs. eIF4A is thought to prepare a ribosome landing pad on mRNA templates for incoming 40S ribosomes (and associated factors). Using small molecule screening, we found that cyclopenta[b]benzofuran flavaglines, a class of natural products, modulate eIF4A activity and inhibit translation initiation. One member of this class of compounds, silvestrol, was able to enhance chemosensitivity in a mouse lymphoma model in which carcinogenesis is driven by phosphatase and tensin homolog (PTEN) inactivation or elevated eIF4E levels. These results establish that targeting translation initiation can restore drug sensitivity in vivo and provide an approach to modulating chemosensitivity.     

Genetic diversity in Hypericum and AFLP Markers for species-specific identification of H. perforatum L

One of the top-selling medicinal products worldwide is Hypericum perforatum (St. John's Wort). Despite its cosmopolitan distribution and utilization, little is known regarding the relationship of the bioactive compounds in H. perforatum to the plants from which they are purportedly derived. In this study, amplified fragment length polymorphism (AFLP) analysis of 56 Hypericum accessions, representing 11 species, was conducted to gain a better understanding of diversity within Hypericum species, especially within cultivated accessions of H. perforatum, and to establish a molecular methodology that will provide breeders and regulators with a simple, affordable, and accurate tool with which to identify purported H. perforatum material. Utilizing four primer combinations, a total of 298 polymorphic markers were generated, of which 17 were present in all H. perforatum accessions and 2 were specific to only H. perforatum. This study demonstrates that AFLP can be utilized not only to determine the relationships of closely related Hypericum accessions, but as a tool to authenticate material in herbal remedies through the use of genetic fingerprinting.     

Use of urine polymerase chain reaction to define the prevalence and clinical presentation of Trichomonas vaginalis in men attending an STD clinic

OBJECTIVE: To determine the prevalence and clinical features of Trichomonas vaginalis (TV) infection in men. METHODS: Men attending a public STD clinic in Baltimore, Maryland, were evaluated between March and July 2000. Clinicians recorded a standardised history and clinical examination. Urethral swab specimens were collected for Gram stain and Neisseria gonorrhoeae culture. First fraction urine samples were evaluated with TV culture and chlamydia and TV polymerase chain reaction (PCR). True positive TV was defined as a positive TV culture or a positive TV PCR confirmed with a second primer set. RESULTS: 355 men were evaluated in 363 visits. The prevalence of gonorrhoea, TV, and chlamydia were 19%, 13%, and 11%, respectively. In men over 28 years, the prevalence of TV was significantly higher than chlamydia. Age and urethritis by Gram stain were associated with a positive result on TV culture (p=0.03 and p=0.02, respectively) but not associated with TV infection as defined by a positive TV culture or a confirmed TV PCR. Discharge or dysuria was reported in 47% and 22% of men with TV, respectively. CONCLUSIONS: TV prevalence in an urban STD clinic setting was high. Older age and urethritis were not significantly associated with TV infection as defined by a positive TV culture or a confirmed TV PCR.