T cell development and T cell responses in mice with mutations affecting tyrosines 292 or 315 of the ZAP-70 protein tyrosine kinase

After stimulation of the T cell receptor (TCR), the tyrosine residues 292 and 315 in interdomain B of the protein tyrosine kinase ZAP-70 become phosphorylated and plausibly function as docking sites for Cbl and Vav1, respectively. The two latter proteins have been suggested to serve as substrates for ZAP-70 and to fine-tune its function. To address the role of these residues in T cell development and in the function of primary T cells, we have generated mice that express ZAP-70 molecules with Tyr to Phe substitution at position 292 (Y292F) or 315 (Y315F). When analyzed in a sensitized TCR transgenic background, the ZAP-70 Y315F mutation reduced the rate of positive selection and delayed the occurrence of negative selection. Furthermore, this mutation unexpectedly affected the constitutive levels of the CD3-zeta p21 phosphoisoform. Conversely, the ZAP-70 Y292F mutation upregulated proximal events in TCR signaling and allowed more T cells to produce interleukin 2 and interferon gamma in response to a given dose of antigen. The observation that ZAP-70 Y292F T cells have a slower rate of ligand-induced TCR downmodulation suggests that Y292 is likely involved in regulating the duration activated TCR reside at the cell surface. Furthermore, we showed that Y292 and Y315 are dispensable for the TCR-induced tyrosine phosphorylation of Cbl and Vav1, respectively. Therefore, other molecules present in the TCR signaling cassette act as additional adaptors for Cbl and Vav1. The present in vivo analyses extend previous data based on transformed T cell lines and suggest that residue Y292 plays a role in attenuation of TCR signaling, whereas residue Y315 enhances ZAP-70 function.     

Elevated plasma total homocysteine in centenarians.

Homocysteine (Hcy) is a sulfur-containing metabolite of methionine and is an emerging independent risk factor for atherosclerosis. Previous studies have shown that age, gender, renal function and folic acid intake are the main factors influencing total plasma Hcy levels in humans. A unique approach to the science of human longevity is the natural model of centenarians. The objective of this study was to verify whether the previously determined risk factors for atherosclerosis and atherosclerosis-related diseases change with age and, finally, to establish the vitamin nutritional status role. We studied 54 centenarians (14 males and 40 females) aged between 100-107 years (mean age 102.6+/-1.8 years) living in Sicily (Italy), recruited via the Registry Office, and compared them with three control groups composed of subjects with different age ranges. Total plasma Hcy, folate, vitamin B12 and pyridoxal phosphate (PLP) levels were compared between the groups by the Student's t test. The comparison between centenarians and <65-year old, randomly selected individuals showed that in centenarians the mean value of serum creatinine levels was 18 micromol/l (p=0.000) higher, the mean total Hcy value was 22 micromol/l higher (p=0.000), the mean PLP value was 17.9 nmol/l lower (p=0.000), the mean folate level was 2.1 nmol/l lower (p<0.001) and vitamin B12 was 70.5 pmol/l lower (p=0.000). The comparison between centenarians and >65-year old, randomly selected individuals showed that in centenarians the mean value of serum creatinine levels was 8 micromol/l higher (p=0.037), the mean total Hcy value was 11.6 micromol/l higher (p=0.000) and the mean PLP value was 4.2 nmol/l higher (p=0.000). It seems that centenarians are protected by some mechanism (maybe genetic) that allows them a long survival despite the high value of homocysteinemia. On the other hand, it can by hypothesized that good vitamin intake is essential to live over 100 years.     

Maximizing the general success of cecal intubation during propofol sedation in a multi-endoscopist academic centre

Background  

Achieving the target of 95% colonoscopy completion rate at centres conducting colorectal screening programs is an important issue. Large centres and teaching hospitals employing endoscopists with different levels of training and expertise risk achieving worse results. Deep sedation with propofol in routine colonoscopy could maximize the results of cecal intubation.     

Oxidative stress and steatosis are cofactors of liver injury in primary biliary cirrhosis

Background

Factors responsible for the progression of primary biliary cirrhosis (PBC) are still poorly understood. In the present study, we investigated the associations between the stage of PBC and the immune reaction triggered by oxidative stress; the presence of obesity, steatosis, steatohepatitis; and other toxic, metabolic, or steatogenic factors.

Methods

We studied clinical, laboratory, and histological data for 274 untreated patients with serum antimitochondrial antibody (AMA)-positive PBC. Circulating IgG against human serum albumin adducted with malondialdeyde, the major product of lipid peroxidation, was measured in these patients and in a group of 98 sex-, age- and body mass index (BMI)-matched controls.

Results

Steatosis was present in 40.5% of all patients. Steatohepatitis was present in 14.9% of all patients. There was a significant association between the frequencies of steatosis and steatohepatitis and the worsening of PBC. Circulating IgG against lipid peroxidation products was significantly higher in the PBC patients than in the controls. Titers of lipid peroxidation-related antibodies were significantly increased in patients with steatosis and in patients at more advanced stages. Bivariate analysis revealed a significant association between indirect evidence of oxidative stress, steatosis, steatohepatitis, age, BMI, frequency of diabetes, alcohol intake, iron grade after Perl’s stain, and PBC stage. Logistic regression analysis confirmed that the titers of antibodies against lipid peroxidation products (odds ratio 4.5, p < .001, 95% confidence interval 3.9–14.4), the presence of steatosis (odds ratio 4.1, 95% confidence interval 2.5–15.4, p < .001), higher BMI (odds ratio 3.9, p < .021, 95% confidence interval 1.4–9.5), and alcohol intake (males ≥ 30 g/day, females ≥ 20 g/day, odds ratio 4.5, 95% confidence interval 1.3–19.8, p < .029) were independently associated with more advanced stages of the disease.

Conclusions

The immune reactions triggered by oxidative stress, steatosis, obesity, and alcohol intake are independent predictors of PBC stage progression.     

Efficacy of postprocedure administration of gabexate mesylate in the prevention of post-ERCP pancreatitis: a randomized, controlled, multicenter study

BACKGROUND AND OBJECTIVE: Gabexate mesylate reduces the incidence of post-ERCP pancreatitis. Patient-related risk factors associated with pancreatitis can be identified before ERCP, but the procedure-related factors are recognized only at the end of the procedure. This study's aim was to evaluate whether gabexate mesylate administered after ERCP reduces the incidence of pancreatitis. DESIGN: Randomized, prospective, double-blind, multicenter trial. SETTING: Tertiary care centers. PATIENTS AND INTERVENTION: A total of 608 patients undergoing ERCP were treated with gabexate mesylate 500 mg within 1 hour before ERCP (group A, 203 patients) or within 1 hour after ERCP (group B, 203), or with saline solution (group C, 202). MAIN OUTCOME MEASUREMENTS: The incidence and severity of pancreatitis and hyperamylasemia, as well as factors associated with the development of pancreatitis. RESULTS: The groups were similar for demographic characteristics, indications to ERCP, risk factors for pancreatitis, and therapeutic procedures. The incidence of pancreatitis was 3.9% in group A, 3.4% in group B, and 9.4% in group C (P<.01). Two patients (in groups A and C) developed necrotizing pancreatitis, and 1 died. Hyperamylasemia occurred in 23.6% in groups A and B, and in 24.7% in group C. Levels of amylase, the incidence of abdominal pain, and other complications occurred similarly. Female sex (odds ratios [OR] 2.7, 95% CI 1.2-5.9) and difficult cannulation (OR 5.6, 95% CI 2.6-12.3) were independently associated with pancreatitis. CONCLUSIONS: The administration of gabexate mesylate after ERCP protects against the development of pancreatitis similarly to the preprocedure administration. Factors associated with pancreatitis were mainly recognized after ERCP. We suggest administering gabexate mesylate after ERCP only in those patients recognized to be at risk of developing pancreatitis.     

Impaired inotropic response in type 2 diabetes mellitus: a strain rate imaging study

BACKGROUND: Left ventricular (LV) concentric geometry and hypertrophy, depressed wall mechanics, and abnormal diastolic properties have been described in the diabetic heart. However, the cardiac response to dynamic exercise in diabetic patients remains controversial. The present study assessed strain rate (SR) imaging during dobutamine stress, to investigate inotropic response in patients with type 2 diabetes mellitus and without coronary artery disease. METHODS: Twenty-four diabetics and 16 controls, both free of coronary artery disease, underwent Doppler echocardiography at rest and during dobutamine stress. Tissue Doppler systolic (S(m)) and early diastolic (E(m)) velocities, SR, and strain of middle posterior septum were measured at rest, low-dose, and high-dose dobutamine. RESULTS: Diabetics had higher LV mass and relative wall thickness, lower midwall shortening, and transmitral pattern of abnormal LV relaxation. At rest, E(m) was significantly lower but S(m), SR, and strain were similar between the two groups. At low-dose and high-dose dobutamine, without difference of S(m), SR and strain were significantly lower in diabetics. At every level of dobutamine, strain increased with increasing heart rate (HR) in either group (both P < .0001), but the slope of the overall relation between HR and strain was lower in diabetics (b = -0.08) than in controls (b = -0.14) (P < .01). CONCLUSIONS: In type 2 diabetes SR imaging allows detection of reduced longitudinal mechanics during dobutamine stress. The blunted slope of the relation between HR and regional strain suggests the impairment of the myocardial force-frequency relation, indicating altered contractile reserve in uncomplicated diabetes.     

Agenesis of the gallbladder

Agenesis of the gallbladder is a rare anomaly that is usually asymptomatic, but sometimes the patients may have symptoms compatible with a biliary disorder like cholelithiasis. Its preoperative diagnosis is often difficult, especially if dysplastic cyst is associated and simulates the gallbladder. When the diagnosis is doubtful its confirmation and treatment of dysplastic cyst require open surgery, careful dissection of the common bile duct to avoid biliary lesions and intraoperative ultrasonography or cholangiography to be performed to exclude other associated anomalies. The Authors describe the case of agenesis of gallbladder and dysplastic cyst associated and comment on its clinical, diagnostic, and therapeutic aspects.     

Complex sleep apnea and obesity hypoventilation syndrome. Opposite ends of the spectrum of obstructive sleep apnea?

In most cases, the application of continuous positive airway pressure (CPAP) during sleep in patients affected by obstructive sleep apnea (OSA) eliminates upper airway obstruction and makes breathing stable and regular. However, some OSA patients develop periodic breathing and central apneas during CPAP administration, a finding that has been labelled as “complex sleep apnea” (complex SA). Such breathing disorder may occur only acutely after CPAP treatment initiation or sometimes persist with chronic CPAP treatment. We hypothesize that complex SA may be the consequence of mechanisms analogous to those leading to obesity hypoventilation syndrome (OHS), but operating in an opposite direction.Periodic breathing is one of the factors predisposing to OSA and is an essential factor for the recurrence of central apneas in normo or hypocapnic patients. A high ventilatory responsiveness to chemical stimuli enhances breathing periodicity. In subjects with periodic central apneas chemoresponsiveness is high, while in subjects with OSA it spans throughout a wide range, and is correlated to diurnal blood gas levels. In fact, sleep respiratory disorders may be responsible for either an augmentation in ventilatory responses to chemical stimuli consequent to chronic exposure to intermittent hypoxia, or for a decrease in ventilatory responses when prolonged exposure to hypercapnia is experienced. Among OSA subjects, those with OHS show very depressed hypercapnic responses. After chronic OSA treatment, ventilatory responses to chemical stimuli may either decrease, in previously hyperresponsive subjects, or increase, in previously hyporesponsive subjects. Most patients with OHS decrease daytime PCO₂ levels and increase their ventilatory responses after chronic CPAP treatment.Complex SA could appear in those OSA subjects in whom chronic exposure to nocturnal respiratory disorders leads to the highest responsiveness to chemical stimuli, and could disappear after blunting of ventilatory responses following chronic CPAP treatment. Complex SA may be one extreme of evolutionary spectrum of OSA, the opposite end being represented by OHS.     

Sulfated K5 Escherichia coli polysaccharide derivatives as wide-range inhibitors of genital types of human papillomavirus

Genital human papillomaviruses (HPV) represent the most common sexually transmitted agents and are classified into low or high risk by their propensity to cause genital warts or cervical cancer, respectively. Topical microbicides against HPV may be a useful adjunct to the newly licensed HPV vaccine. A main objective in the development of novel microbicides is to block HPV entry into epithelial cells through cell surface heparan sulfate proteoglycans. In this study, selective chemical modification of the Escherichia coli K5 capsular polysaccharide was integrated with innovative biochemical and biological assays to prepare a collection of sulfated K5 derivatives with a backbone structure resembling the heparin/heparan biosynthetic precursor and to test them for their anti-HPV activity. Surface plasmon resonance assays revealed that O-sulfated K5 with a high degree of sulfation [K5-OS(H)] and N,O-sulfated K5 with a high [K5-N,OS(H)] or low [K5-N,OS(L)] sulfation degree, but not unmodified K5, N-sulfated K5, and O-sulfated K5 with low levels of sulfation, prevented the interaction between HPV-16 pseudovirions and immobilized heparin. In cell-based assays, K5-OS(H), K5-N,OS(H), and K5-N,OS(L) inhibited HPV-16, HPV-18, and HPV-6 pseudovirion infection. Their 50% inhibitory concentration was between 0.1 and 0.9 mug/ml, without evidence of cytotoxicity. These findings provide insights into the design of novel, safe, and broad-spectrum microbicides against genital HPV infections.