PRKAR1A inactivation leads to increased proliferation and decreased apoptosis in human B lymphocytes

The multiple neoplasia syndrome Carney complex (CNC) is caused by heterozygote mutations in the gene, which codes for the RIalpha regulatory subunit (PRKAR1A) of protein kinase A. Inactivation of PRKAR1A and the additional loss of the normal allele lead to tumors in CNC patients and increased cyclic AMP signaling in their cells, but the oncogenetic mechanisms in affected tissues remain unknown. Previous studies suggested that PRKAR1A down-regulation may lead to increased mitogen-activated protein kinase (MAPK) signaling. Here, we show that, in lymphocytes with PRKAR1A-inactivating mutations, there is increased extracellular signal-regulated kinase (ERK) 1/2 and B-raf phosphorylation and MAPK/ERK kinase 1/2 and c-Myc activation, whereas c-Raf-1 is inhibited. These changes are accompanied by increased cell cycle rates and decreased apoptosis that result in an overall net gain in proliferation and survival. In conclusion, inactivation of PRKAR1A leads to widespread changes in molecular pathways that control cell cycle and apoptosis. This is the first study to show that human cells with partially inactivated RIalpha levels have increased proliferation and survival, suggesting that loss of the normal allele in these cells is not necessary for these changes to occur.     

HLA-DQB1*06:02 allele frequency and clinic-polysomnographic features in Saudi Arabian patients with narcolepsy

Sleep and Breathing - Narcolepsy is an uncommon neurological disorder characterised by irresistible spells of sleep associated with abnormal rapid eye movement (REM) sleep. The association between...     

IL-7 promotes T cell proliferation through destabilization of p27Kip1

Interleukin (IL)-7 is required for survival and homeostatic proliferation of T lymphocytes. The survival effect of IL-7 is primarily through regulation of Bcl-2 family members; however, the proliferative mechanism is unclear. It has not been determined whether the IL-7 receptor actually delivers a proliferative signal or whether, by promoting survival, proliferation results from signals other than the IL-7 receptor. We show that in an IL-7-dependent T cell line, cells protected from apoptosis nevertheless underwent cell cycle arrest after IL-7 withdrawal. This arrest was accompanied by up-regulation of the cyclin-dependent kinase inhibitor p27Kip1 through a posttranslational mechanism. Overexpression of p27Kip1 induced G1 arrest in the presence of IL-7, whereas knockdown of p27Kip1 by small interfering RNA promoted S phase entry after IL-7 withdrawal. CD4 or CD8 T cells transferred into IL-7-deficient hosts underwent G1 arrest, whereas 27Kip1-deficient T cells underwent proliferation. We observed that IL-7 withdrawal activated protein kinase C (PKC)theta and that inhibition of PKCtheta with a pharmacological inhibitor completely blocked the rise of p27Kip1 and rescued cells from G1 arrest. The conventional pathway to breakdown of p27Kip1 is mediated by S phase kinase-associated protein 2; however, our evidence suggests that PKCtheta acts via a distinct, unknown pathway inducing G1 arrest after IL-7 withdrawal from T cells. Hence, IL-7 maintains T cell proliferation through a novel pathway of p27Kip1 regulation.     

Characterization of rpoB mutations in rifampin-resistant clinical Mycobacterium tuberculosis isolates from Kuwait and Dubai

Mutations conferring resistance to rifampin in rifampin-resistant clinical Mycobacterium tuberculosis isolates occur mostly in the 81 bp rifampin-resistance-determining region (RRDR) of the rpoB gene. In this study, 29 rifampin-resistant and 12 -susceptible clinical M. tuberculosis isolates were tested for characterization of mutations in the rpoB gene by line probe (INNO-LiPA Rif. TB) assay and the results were confirmed and extended by DNA sequencing of the PCR amplified target DNA. The line probe assay identified all 12 susceptible strains as rifampin-sensitive and the DNA sequence of RRDR in the amplified rpoB gene from two isolates matched perfectly with the wild-type sequence. The line probe assay identified 28 resistant isolates as rifampin-resistant with specific detection of mutation in 22 isolates including one isolate that exhibited hetro-resistance containing both the wild-type pattern as well as a specific mutation within RRDR while one of the rifampin-resistant strain was identified as rifampin-susceptible. DNA sequencing confirmed these results and, in addition, led to the specific detection of mutations in 5 rifampin-resistant isolates in which specific base changes within RRDR could not be determined by the line probe assay. These analyses identified 8 different mutations within RRDR of the rpoB gene including one novel mutation (S522W) that has not been reported so far. The genotyping performed on the isolates carrying similar mutations showed that majority of these isolates were unique as they exhibited varying DNA banding patterns. Correlating the ethnic origin of the infected TB patients with the occurrence of specific mutations at three main codon positions (516, 526 and 531) in the rpoB gene showed that most patients (11 of 15) from South Asian region contained mutations at codon 526 while majority of isolates from patients (6 of 11) of Middle Eastern origin contained mutations at codon 531.     

Braden scale for pressure ulcer risk predicts rehabilitation placement after pancreatic resection

BackgroundPatients undergoing pancreatic resection frequently require rehabilitation facilities after hospital discharge. We evaluated the predictive role of validated markers of frailty on rehabilitation facility placement to identify patients who may require this service.MethodsSingle-center retrospective cohort study of patients who underwent pancreatic resection from 2010 to 2015. 90-day morbidity and mortality were calculated. Postoperative validated markers of frailty (Activities of Daily Living scale, Braden scale [assesses pressure ulcer risk, lower scores = higher risk] and Morse fall scale) were evaluated via multivariate regression to identify predictors of discharge to rehabilitation facility.Results470 patients with complete data were included. Mean age was 62 and 49.2% were male. Postoperative median length of stay (LOS) was 8 (IQR 7–10). 92 (19.66%) patients were discharged to rehabilitation facilities and 138 (29.49%) patients were readmitted within 90 days. On multivariate analysis, age, sex, LOS > 8 days, inpatient Comprehensive Complication Index (CCI) and initial Braden scale were predictive of rehabilitation placement.ConclusionA marker of frailty routinely collected daily by nursing staff, the Braden scale, is available to help surgeons predict the need for postoperative rehabilitation placement after pancreatic resection. Engaging discharge planning services for at-risk patients may help prevent delayed hospital discharge and should be further evaluated.     

Prevalence of antibodies to human caliciviruses (HuCVs) in Kuwait established by ELISA using baculovirus-expressed capsid antigens representing two genogroups of HuCVs

Baculovirus recombinant-expressed antigens of Norwalk viruses (rNV) and a Mexico strain (rMX) of the Snow Mountain serogroup of human caliciviruses (HuCVs) were used in enzyme immunoassays to study the antibody prevalence among the Kuwaiti population and foreign workers employed in Kuwait. The antibody titers in 16 different age groups which ranged from neonates to centenarians were investigated by testing eight different dilutions of each serum (1:200–1:25,600). The results indicate that NV infection is widespread in Kuwait and affects all age groups. Ninety-eight percent of the 433 serum samples tested had antibodies to rNV. In the 50–79-year-old age group, the antibody levels to rNV were higher and significantly different from those in children 0–7 years old. In infants, the rNV antibodies did not diminish by 4 months of age and their titer steadily increased with age. When 414 of these sera samples were tested for antibodies to rMX, 96% positive serological responses were observed. Antibody titers to rMX were reduced in infants from 4 to 11 months; however, 95% of the samples were positive. These data indicate that children born in Kuwait are infected with Norwalk-like viruses at a very early age. Finally, antibodies to rNV and rMX were found in 98% of 151 and in 95% of 148 foreign workers, respectively. J Med Virol 51:115–118, 1997. © 1997 Wiley-Liss, Inc.     

Non-vitamin K antagonist oral anticoagulants for the treatment of intracardiac thrombosis

Intracardiac thrombus most commonly develops in the left atrial appendage (LAA) and left ventricle (LV) in the setting of atrial fibrillation (AF) and post-myocardial fibrillation (MI), respectively. Current guidelines recommend that patients with post-MI LV or LAA thrombus should be treated with vitamin K antagonist (VKA). However, the use of VKA may be limited by bleeding complications, interactions with various food and drugs, and a narrow therapeutic window requiring frequent monitoring. Thus, non-VKA oral anticoagulants (NOACs) have been attempted as an off-label use for the treatment of intracardiac thrombosis in light of their favorable pharmacologic profile. Until now, therapeutic effect of NOACs on intracardiac thrombosis has not been formally studied in large randomized controlled trials. This article aims to systematically review the literature regarding efficacy and safety outcome of NOACs in the management of intracardiac thrombus. Considering the high rate of complete thrombus resolution and low rate of thromboembolic or hemorrhagic complications, preliminary evidence from case series and reports indicate that NOACs (including factor Xa inhibitors and direct thrombin inhibitors) may be a safe and effective therapeutic option for intracardiac thrombosis, particularly in cases resistant to VKA therapy.