Intraocular pressure profile during the modified diurnal tension curve using Goldman applanation tonometry and dynamic contour tonometry

The aim of this study was to compare the intraocular pressure (IOP) profile during the modified diurnal tension curve (mDTC) using Goldman applanation tonometry (GAT) and dynamic contour tonometry (DCT) in treated glaucomatous eyes. Eligible subjects were submitted to the mDTC using GAT and DCT in this sequence. IOP measurements were performed at 8 a.m., 10 a.m., 2 p.m., and 4 p.m.. Central corneal thickness was measured using ultrasound pachymetry in the morning. Statistical analysis was performed using paired Student’s t test and Bland–Altman plot. The mean difference between DCT and GAT measurements was 0.9 mmHg. The mean ± SD IOP measurements during the mDTC were 19.68 ± 4.68, 17.63 ± 4.44, 17.25 ± 5.41, and 17.32 ± 4.25 mmHg using GAT and 19.97 ± 4.75, 18.79 ± 4.61, 19.53 ± 5.30, and 19.43 ± 5.45 mmHg using DCT. IOP measurements were higher in the morning (8 a.m.) and decreased throughout the day using both tonometers. The difference between IOP measurements using GAT and DCT was smaller in the morning and increased throughout the day. The IOP variability using GAT was higher than using DCT. Corneal biomechanical properties might help explain our findings.     

Transfusion-transmitted infectious diseases

A spectrum of blood-borne infectious agents is transmitted through transfusion of infected blood donated by apparently healthy and asymptomatic blood donors. The diversity of infectious agents includes hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency viruses (HIV-1/2), human T-cell lymphotropic viruses (HTLV-I/II), Cytomegalovirus (CMV), Parvovirus B19, West Nile Virus (WNV), Dengue virus, trypanosomiasis, malaria, and variant CJD. Several strategies are implemented to reduce the risk of transmitting these infectious agents by donor exclusion for clinical history of risk factors, screening for the serological markers of infections, and nucleic acid testing (NAT) by viral gene amplification for direct and sensitive detection of the known infectious agents. Consequently, transfusions are safer now than ever before and we have learnt how to mitigate risks of emerging infectious diseases such as West Nile, Chikungunya, and Dengue viruses.     

High-level expression and purification of human thymidine kinase 1: quaternary structure, stability, and kinetics

Human cytosolic thymidine kinase (hTK1) is the key enzyme of the pyrimidine salvage pathway and phosphorylates thymidine to thymidine monophosphate, a precursor building block of the DNA. Wild-type hTK1 (hTK1W) as well as a truncated form of the enzyme (hTK1M) carrying deletions at the N- and C-terminal regions were cloned as His(6)-tagged fusion proteins. Expression, isolation, and purification protocols have been established, leading to high yields of soluble and active wild type (approximately 35 mg) and truncated hTK1 (approximately 23 mg) per liter of culture. The protein was purified to near homogeneity. The chaperone DnaK was identified to be the major contaminant that could be removed by applying an additional ATP-MgCl(2) incubation and washing step. hTK1W was a permanent tetramer in solution, whereas the truncated construct hTK1M appears to be a dimer in absence and presence of substrates. Both hTK1W and hTK1M exhibit pronounced thermal stability with transition temperatures (T(m)) of 71.7 and 73.4 degrees C, respectively, when measured without adding substrates. The presence of substrates stabilized both hTK1W (DeltaT(m) ranging from 5.6 to 12.5 degrees C) and hTK1M (DeltaT(m) ranging from 0.8 to 5.3 degrees C). Both enzymes show high activity over a broad range of pH, temperature, and ionic strength. Kinetic studies determined a K(M) of 0.51 microM and a k(cat) of 0.28 s(-1) for wild-type hTK1. The truncated hTK1M has a K(M) of 0.87 microM and k(cat) of 1.65 s(-1), thus exhibiting increased catalytic efficiency. The availability of recombinant human TK1 will facilitate further biochemical and crystallographic studies.     

Cerebral blood flow during cardiopulmonary bypass in pediatric cardiac surgery: the role of transcranial Doppler – a systematic review of the literature

Background

Transcranial Doppler Ultrasound (TCD) is a sensitive, real time tool for monitoring cerebral blood flow velocity (CBFV). This technique is fast, accurate, reproducible and noninvasive. In the setting of congenital heart surgery, TCD finds application in the evaluation of cerebral blood flow variations during cardiopulmonary bypass (CPB).

Methodology

We performed a search on human studies published on the MEDLINE using the keyword "trans cranial Doppler" crossed with "pediatric cardiac surgery" AND "cardio pulmonary by pass", OR deep hypothermic cardiac arrest", OR "neurological monitoring".

Discussion

Current scientific evidence suggests a good correlation between changes in cbral blood flow and mean cerebral artery (MCA) blood flow velocity. The introduction of Doppler technology has allowed an accurate monitorization of cerebral blood flow (CBF) during circulatory arrest and low-flow CPB. TCD has also been utilized in detecting cerebral emboli, improper cannulation or cross clamping of aortic arch vessels. Limitations of TCD routine utilization are represented by the need of a learning curve and some experience by the operators, as well as the need of implementing CBF informations with, for example, data on brain tissue oxygen delivery and consumption.

Conclusion

In this light, TCD plays an essential role in multimodal neurological monitorization during CPB (Near Infrared Spectroscopy, TCD, processed electro encephalography) that, according to recent studies, can help to significantly improve neurological outcome after cardiac surgery in neonates and pediatric patients.     

Asymmetric growth and development of the Xenopus laevis retina during metamorphosis is controlled by type III deiodinase

During the metamorphosis of the Xenopus laevis retina, thyroid hormone (TH) preferentially induces ventral ciliary marginal zone (CMZ) cells to both increase their proliferation and give rise to ipsilaterally projecting ganglion cells. Here we show that dorsal CMZ cells express type III deiodinase (D3), an enzyme that inactivates TH. The dorsal CMZ cells can be induced to proliferate if deiodinase activity is inhibited. D3 or dominant-negative thyroid hormone receptor transgenes inhibit both TH-induced proliferation of the ventral CMZ cells and the formation of the ipsilateral projection. Thus, the localized expression of D3 in the dorsal CMZ cells accounts for the asymmetric growth of the frog retina.     

Synthesis and opioid activity of N,N-dimethyl-Dmt-Tic-NH-CH(R)-R' analogues: acquisition of potent delta antagonism

N,N-Dimethylation of the H-Dmt-Tic-NH-CH(R)-R′ series of compounds produced no significant affect on the high δ-opioid receptor affinity (K_i=0.035–0.454 nM), but dramatically decreased that for the μ-opioid receptor. The effect of N-methylation was independent of the length of the linker (R); however, the bioactivities were affected by the chemical composition of the third aromatic group (R′): phenyl (Ph) (5′–8′) elicited a greater reduction in μ-affinity (40–70-fold) compared to analogues containing 1H-benzimidazole-2-yl (Bid) (9-fold). The major consequences of N,N-dimethylation on in vitro bioactivity were: (i) a loss of δ-agonism coupled with the appearance of potent δ antagonism (4′–7′) (pA₂=8.14–9.47), while 1 exhibited only a 160-fold decreased δ agonism (1′) and the δ antagonism of 8 enhanced >10-fold (pA₂=10.62, 8′); and (ii) a consistent loss of μ-affinity resulted in enhanced δ-opioid receptor selectivity. With the exception of compound 1′, the change in the hydrophobic environment at the N-terminus and formation of a tertiary amine by N,N-dimethylation in analogues of the Dmt-Tic pharmacophore produced potent δ-selective antagonists.     

Type I IFN protects permissive macrophages from Legionella pneumophila infection through an IFN-gamma-independent pathway

Legionella pneumophila is an intracellular pathogen whose replication in macrophages is mainly controlled by IFN-gamma. Freshly isolated peritoneal macrophages elicited in vivo with thioglycolate (TG) from A/J mice are highly permissive to L. pneumophila growth in vitro, while TG-elicited macrophages from CD1 mice are resistant. In this study, we show that when CD1 TG-macrophages are cultured for 7 days, they become permissive to Legionella infection. We demonstrate that treatment with type I IFN (IFN-alphabeta) totally inhibits the growth of L. pneumophila in both freshly isolated A/J and in vitro-aged CD1 TG-macrophages. IFN-alphabeta protective effect on permissive macrophages was comparable to that induced by IFN-gamma. Even low doses of either IFN-alpha or IFN-beta alone were effective in inhibiting L. pneumophila multiplication in macrophage cultures. Notably, treatment of resistant, freshly isolated CD1 TG-macrophages with Ab to mouse IFN-alphabeta significantly enhanced their susceptibility to Legionella infection in vitro, thus implying a role of endogenous IFN-alphabeta in mediating the natural resistance of macrophages to L. pneumophila infection. Finally, addition of anti-IFN-gamma-neutralizing Ab did not restore Legionella growth in IFN-alpha- or IFN-beta-treated A/J or CD1 permissive macrophages, indicating that IFN-alphabeta effect was not mediated by IFN-gamma. This observation was further confirmed by the finding that IFN-alphabeta was effective in inhibiting L. pneumophila replication in macrophages from IFN-gamma receptor-deficient mice. Taken together, our results provide the first evidence for a role of IFN-alphabeta in the control of L. pneumophila infection in mouse models of susceptible macrophages and suggest the existence of different pathways for the control of intracellular bacteria in macrophages.     

Blockade of nociceptin/orphanin FQ transmission in rat substantia nigra reverses haloperidol-induced akinesia and normalizes nigral glutamate release

We recently showed that pharmacological blockade of nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptors located in the substantia nigra stimulates the nigrostriatal dopaminergic pathway and motor behavior (Marti et al. J. Neurosci. 2004, 24, 6659-6666). To investigate whether such motor-stimulating action was dependent on functional dopaminergic transmission, the selective NOP receptor peptide antagonist [Nphe1,Arg14,Lys15]N/OFQ-NH2 (UFP-101) was microinjected into the substantia nigra reticulata of rats made cataleptic by systemic haloperidol administration. UFP-101 reduced haloperidol-induced akinesia as measured by immobility time in the bar test. UFP-101 also induced contralateral turning in cataleptic rats. To investigate the mechanisms involved in the anti-akinetic action of UFP-101, nigral glutamate release was monitored by microdialysis technique. The anti-akinetic action of UFP-101 correlated with normalization of nigral glutamate release, previously elevated by haloperidol injection. We conclude that endogenous N/OFQ in the substantia nigra sustains akinesia generated by impaired DA transmission and subthalamic nucleus overactivation. NOP receptor antagonists may be beneficial in the symptomatic therapy of parkinsonism, via normalization of subthalamonigral glutamatergic transmission.     

Werner's syndrome lymphoblastoid cells are hypersensitive to topoisomerase II inhibitors in the G2 phase of the cell cycle

Werner's syndrome (WS) is a rare autosomal recessive human disorder and the patients exhibit many symptoms of accelerated ageing in their early adulthood. The gene (WRN) responsible for WS has been biochemically characterised as a 3'-5' helicase and is homologous to a number of RecQ superfamily of helicases. The yeast SGS1 helicase is considered as a human WRN homologue and SGS1 physically interacts with topoisomerases II and III. In view of this, it has been hypothesised that the WRN gene may also interact with topoisomerases II and III. The purpose of this study is to determine whether the loss of function of WRN protein alters the sensitivity of WS cells to agents that block the action of topoisomerase II. This study deals with the comparison of the chromosomal damage induced by the two anti-topoisomerase II drugs, VP-16 and amsacrine, in both G1 and G2 phases of the cell cycle, in lymphoblastoid cells from WS patients and from a healthy donor. Our results show that the WS cell lines are hypersensitive to chromosome damage induced by VP-16 and amsacrine only in the G2 phase of the cell cycle. No difference either in the yield of the induced aberrations or SCEs was found after treatment of cells at G1 stage. These data might suggest that in WS cells, because of the mutation of the WRN protein, the inhibition of topoisomerase II activity results in a higher rate of misrepair, probably due to some compromised G2 phase processes involving the WRN protein.