Diagnostic capability of biological markers in assessment of obstructive sleep apnea: a systematic review and meta-analysis.

OBJECTIVE: The purpose of this systematic review is to evaluate the diagnostic value of biological markers (exhaled breath condensate, blood, salivary and urinary) in the diagnosis of OSA in comparison to the gold standard of nocturnal PSG. METHODS: Studies that differentiated OSA from controls based on PSG results, without age restriction, were eligible for inclusion. The sample of selected studies could include studies in obese patients and with known cardiac disease. A detailed individual search strategy for each of the following bibliographic databases was developed: Cochrane, EMBASE, MEDLINE, PubMed, and LILACS. The references cited in these articles were also crosschecked and a partial grey literature search was undertaken using Google Scholar. The methodology of selected studies was evaluated using the 14-item Quality Assessment Tool for Diagnostic Accuracy Studies. RESULTS: After a two-step selection process, nine articles were identified and subjected to qualitative and quantitative analyses. Among them, only one study conducted in children and one in adults found biomarkers that exhibit sufficiently satisfactory diagnostic accuracy that enables application as a diagnostic method for OSA. CONCLUSION: Kallikrein-1, uromodulin, urocotin-3, and orosomucoid-1 when combined have enough accuracy to be an OSA diagnostic test in children. IL-6 and IL-10 plasma levels have potential to be good biomarkers in identifying or excluding the presence of OSA in adults.

The kinin system in patients with systemic lupus erythematosus exhibiting mucocutaneous lesions: a clinical study.

In the present study, we evaluated the kinin system components in the plasma of patients with systemic lupus erythematosus exhibiting mucocutaneous lesions. Fifteen women with active cutaneous lupus (P) and 15 normal healthy women (C) were studied. Low molecular (LKg) and high molecular (HKg) weight kininogen were determined by ELISA (expressed microg Bk/ml). The activities of tissue kallikrein (TKal), plasma kallikrein (PKal) and kininase II were assayed by their action on selective substrates. Statistical analysis was performed using the Mann-Whitney test. The patients presented increased plasma levels of LKg (P = 2.98, C = 0.79) and HKg (P = 1.78, C = 0.5) associated with the increased activity of PKal (P = 2.50, C = 1.63 U/ml), TKal (P = 1.87, C = 1.30 microM pNa/ml) and kininase II (P = 1.50, C = 0.51 microM Hys-Leu/ml), when compared to the values observed in the control group (P < 0.0001 for each comparison). Thus, the increased concentration of all parameters of the kinin system in these patients indicate an overactivity of the kinin system in the acute phase of lupus, corroborating with the participation of these mediators in lupus pathogenesis.

Increased activity of plasma and tissue kallikreins, plasma kininase II and salivary kallikrein in pemphigus foliaceus (fogo selvagem).

BACKGROUND: Pemphigus foliaceus (PF) is an autoimmune blistering disease of unknown aetiology, which is endemic in Brazil. Although the pathogenesis of PF is still unknown, proteins of the contact system have been implicated. OBJECTIVES: As the components of the kinin system may interact with those of the contact system, in this study we evaluated the plasma levels of high-molecular-weight kininogen (HK) and low-molecular-weight kininogen (LK), and the activity of plasma kallikrein, tissue kallikrein and kininase II in plasma of patients with PF presenting with Nikolsky's sign. As kidneys and salivary glands are relevant sources of tissue kallikrein for plasma, we also evaluated urinary/salivary kallikrein and urinary kininase II activities. METHODS: Fifteen patients and 15 age- and sex-matched controls were studied. Kininogen levels were determined by enzyme-linked immunosorbent assay, and the activities of kallikreins and kininase II were determined using selective chromogenic substrates. RESULTS: Compared with controls, plasma HK levels were decreased (P = 0.031), whereas the activities of plasma kallikrein, tissue kallikrein and kininase II in plasma, and the activity of salivary kallikrein, were increased in patients (P < 0.001 for each comparison). Plasma levels of LK and the activities of urinary kallikrein and urinary kininase II were not significantly different from controls. CONCLUSIONS: Diminished levels of HK associated with increased activities of plasma kallikrein and kininase II indicate that the kinin system is activated at the systemic level in PF. As active plasma kallikreins may act on some proteins of the contact system, it is possible that the enzyme may contribute to blister formation. The further observation of an increased tissue kallikrein activity at the systemic and saliva levels may be interpreted as a systemic reflex of skin inflammation. Whether the activation of the kinin system is a cause or a consequence of blister formation needs further clarification.

Kinins and cytokines in plasma and cerebrospinal fluid of patients with neuropsychiatric lupus.

OBJECTIVE: To evaluate the kinin system components and selected cytokines in plasma and cerebrospinal fluid (CSF) of patients with neuropsychiatric lupus (NPL). METHODS: We studied 29 women with active NPL and 29 healthy women matched to patients for age. Low (LKg) and high molecular weight kininogen (HKg) and cytokine concentrations [interleukin 1beta (IL-1beta), IL-6, IL-8, IL-10, and tumor necrosis factor-a (TNF-a)] were determined by ELISA. The activities of tissue kallikrein, plasma prekallikrein, and kininase II were assayed by their action on selective substrates. RESULTS: Compared to controls, patients with NPL presented increased plasma and CSF levels of LKg, HKg, and prekallikrein, increased activity of tissue kallikrein and kininase II, and increased levels of IL-6, IL-10, and TNF-a (p < 0.001 each comparison). IL-1beta levels were increased in patient plasma (p < 0.001), whereas plasma IL-8 levels did not differ from controls. IL-1beta and IL-8 were not detected in CSF of patients or controls. CONCLUSION: The increased levels of kininogen fractions, kallikreins, and kininase II in patient plasma and CSF indicate overactivity of the kinin system, suggesting intense kinin production. Since kinins may induce the production of proinflammatory cytokines including IL-1beta, IL-6, and TNF-a, these findings support the participation of kinins and cytokines in the acute manifestations of NPL. Most of the variables evaluated in patients' CSF increased proportionally in relation to plasma levels. In contrast, the activity of tissue kallikrein in patient CSF increased out of proportion to plasma levels, appearing to be locally synthesized in response to brain involvement.

The hepatic clearance of recombinant tissue-type plasminogen activator decreases after an inflammatory stimulus

We have shown that tissue-type plasminogen activator (tPA) and plasma kallikrein share a common pathway for liver clearance and that the hepatic clearance rate of plasma kallikrein increases during the acute-phase (AP) response. We now report the clearance of tPA from the circulation and by the isolated, exsanguinated and in situ perfused rat liver during the AP response (48-h ex-turpentine treatment). For the sake of comparison, the hepatic clearance of a tissue kallikrein and thrombin was also studied. We verified that, in vivo, the clearance of 125I-tPA from the circulation of turpentine-treated rats (2.2 + or - 0.2 ml/min, N = 7) decreases significantly (P = 0.016) when compared to normal rats (3.2 + or - 0.3 ml/min, N = 6). The AP response does not modify the tissue distribution of administered 125I-tPA and the liver accounts for most of the 125I-tPA (>80 percent) cleared from the circulation. The clearance rate of tPA by the isolated and perfused liver of turpentine-treated rats (15.5 + or - 1.3 µg/min, N = 4) was slower (P = 0.003) than the clearance rate by the liver of normal rats (22.5 + or - 0.7 µg/min, N = 10). After the inflammatory stimulus and additional Kupffer cell ablation (GdCl3 treatment), tPA was cleared by the perfused liver at 16.2 + or - 2.4 µg/min (N = 5), suggesting that Kupffer cells have a minor influence on the hepatic tPA clearance during the AP response. In contrast, hepatic clearance rates of thrombin and pancreatic kallikrein were not altered during the AP response. These results contribute to explaining why the thrombolytic efficacy of tPA does not correlate with the dose administered