Alpha-thalassemia in two Mediterranean populations

We used restriction endonuclease analysis to determine the incidence of alpha-thalassemia in two Mediterranean islands. In a random population sample, the gene frequency of deletion-type alpha-thalassemia-2 (- alpha) was 0.18 in Sardinians and 0.07 in Greek Cypriots. All cases were the rightward crossover type. From these frequencies and the known incidence of hemoglobin-H disease in these populations, we calculated the frequency of the alpha-thalassemia-1 genotype (--) and determined that it was low. We also found that beta-thalassemia homozygotes in sardinia have a higher incidence of alpha-thalassemia than normals and beta thalassemia heterozygotes because a significantly greater number of these homozygotes are also homozygous for the alpha-thalassemia-2 lesion. These findings support the theory that coinheritance of alpha- thalassemia mitigates the severity of beta-thalassemia and suggest that the protection is most pronounced when two alpha-globin genes are deleted.     

Clinical dose-volume histogram analysis in predicting radiation pneumonitis in Hodgkin's lymphoma

PURPOSE: To quantify the incidence of radiation pneumonitis (RP) in a modern Hodgkin's lymphoma (HL) cohort, and to identify any clinically relevant parameters that may influence the risk of RP. METHODS AND MATERIALS: Between January 2003 and February 2005, 64 consecutive HL patients aged 18 years or older receiving radical mediastinal radiation therapy (RT) were retrospectively reviewed. Symptomatic cases of radiation pneumonitis were identified. Dose-volume histogram parameters, including V(13), V(20), V(30), and mean lung dose (MLD), were quantified. RESULTS: At a median follow-up of 2.1 years, the actuarial survival for all patients was 91% at 3 years. There were 2 (2/64) cases of Radiation Therapy Oncology Group (RTOG) Grade 2 RP (incidence 3.1%). Both index cases with corresponding V(20) values of 47.0% and 40.7% were located in the upper quartile (2/16 cases), defined by a V(20) value of > or =36%, an incidence of 12.5% (p = 0.03). Similarly for total MLD, both index cases with values of 17.6 Gy and 16.4 Gy, respectively, were located in the upper quartile defined by MLD > or =14.2 Gy, an incidence of 11.8% (2/17 cases, p = 0.02). CONCLUSIONS: Despite relatively high V(20) values in this study of HL patients, the incidence of RP was only 3%, lower compared with the lung cancer literature. We suggest the following clinically relevant parameters be considered in treatment plan assessment: a V(20) greater than 36% and an MLD greater than 14 Gy, over and above which the risk of RTOG Grade 2 or greater RP would be considered clinically significant.     

Chemical modification of the human ether-a-go-go-related gene (HERG) K+ current by the amino-group reagent trinitrobenzene sulfonic acid

We investigated the effects of trinitrobenzene sulfonic acid (TNBS), an amino-group reagent, on the human ether-a-go-go-related gene (HERG) K+ channels expressed in Xenopus oocytes. TNBS neutralizes the positively charged amino-groups of peptide N-terminal and lysine residues. External application of TNBS at 10 mM for 5 min irreversibly shifted the curves for currents at the end of the pulse and tail currents of HERG to a more negative potential and decreased the maximal amplitude of the I(tail) curve (I(tail,max)). TNBS had little effect on either the activated current-voltage relationship or the reversal potential of HERG current, indicating that TNBS did not change ion selectivity properties. TNBS shifted the time constant curves of both activation and deactivation of the HERG current to a more hyperpolarized potential; TNBS's effect was greater on channel opening than channel closing. External H+ is known to inhibit HERG current by shifting V(1/2) to the right and decreasing I(tail,max). TNBS enhanced the blockade of external H+ by exaggerating the effect of H+ on I(tail,max), not on V(1/2). Our data provide evidence for the presence of essential amino-groups that are associated with the normal functioning of the HERG channel and evidence that these groups modify the blocking effect of external H+ on the current.     

Inspiratory flow rates during hard work when breathing through different respirator inhalation and exhalation resistances

There has been a long-standing debate regarding the adequacy of airflow rates used in respirator certification testing and whether these test flow rates underestimate actual values. This study investigated breath by breath inspiratory peak flow rate, minute ventilation, and instantaneous flow rates of eight young, healthy volunteers walking on a treadmill at 80-85% of maximal aerobic capacity until exhaustion while wearing an air-purifying respirator with one of eight combinations of inhalation and exhalation resistance. An analysis of variance was performed to identify differences among the eight conditions. Scheffe's post hoc analysis indicated which means differed. The group of conditions with the highest average value for each parameter was identified and considered to represent a worst-case scenario. Data was reported for these conditions. A Gaussian distribution was fit to the data and the 99.9% probability levels determined. The 99.9% probability level for the peak and instantaneous flow rates were 374 L/min and 336 L/min, respectively. The minute ventilation distribution was not Gaussian. Less than 1% of the recorded minute ventilations exceeded 135 L/min. Instantaneous flow rates exceeded the National Institute for Occupational Safety and Health's respirator test standards of 64, 85, and 100 L/min constant flow 91%, 87%, and 82% of the time, respectively. The recorded minute ventilations exceeded the 40 L/min minute ventilation test standard (for tests with a sinusoidal flow pattern) 100% of the time. This study showed that young, healthy respirator wearers generated peak flow rates, minute ventilations, and instantaneous flow rates that consistently exceeded current test standards. Their flow rates should be higher than those of a respirator wearer performing occupational work and could be considered upper limits. Testing respirators and respirator cartridges using a sinusoidal breathing pattern with a minute ventilation of 135 L/min (peak flow rate approximately 424 L/min) would encompass 99% of the recorded minute ventilations and 99.9% of the predicted peak and instantaneous flow rates from this study and would more accurately reflect human respiration during strenuous exercise.     

Detection of aristolochic acid I, tetrandrine and fangchinoline in medicinal plants by high performance liquid chromatography and liquid chromatography/mass spectrometry

Problems with identification and labeling of medicinal plants, as well as substitution/adulteration of non-toxic plants by toxic ones have previously led to cancer, renal failure and even deaths. The non-toxic Stephania tetrandra (Fangji) has been known to be substituted by Aristolochia fangchi (Guang fangji), which contains the nephrotoxic and carcinogenic aristolochic acid (AA). In this study, 10 samples of "Fangji" were bought from local medicinal shops. HPLC-DAD chromatographic fingerprints of each methanol extract were compared with those of A. fangchi and S. tetrandra, using aristolochic acid I (AAI), tetrandrine and fangchinoline as marker compounds. Nine of the samples were found to be similar to A. fangchi. The presence of AAI in the nine samples was confirmed using LC-MS/MS. Neither tetrandrine nor fangchinoline were detected in these samples. The methods developed in this study allow the simultaneous detection of AAI, fangchinoline and tetrandrine. The results suggest possible substitution of S. tetrandra by A. fangchi at wholesale or retail level. This study highlights the importance of greater control of medicinal plants with toxic components as these may still be readily accessible to the public.     

Paradoxical increase of visual impairment with punctal occlusion in a patient with mild dry eye

We report a paradoxical increase in visual impairment after punctal plug placement despite improvement in corneal epithelial damage caused by mild dry eye. Ocular higher-order aberrations (HOAs) were measured sequentially with a wavefront sensor before and after punctal plug insertion in a patient with mild dry eye. Although postblink HOAs tend to increase in normal subjects or patients with dry eye, after treatment there was a maximum spike in HOAs for a few seconds that decreased gradually. Excessive retention of tear film by punctal occlusion may cause inferosuperior asymmetrical distribution in precorneal tear-film thickness, possibly leading to slower wavefront on the inferior cornea and increased coma-like aberrations. Increased visual impairment might occur paradoxically despite improvement in the corneal epithelial damage caused by dry eye.     

Indocyanine green angiographic features of myopic subfoveal choroidal neovascularization as a prognostic factor after photodynamic therapy

PURPOSE: To determine the influence of clinical features and Indocyanine green (ICG) angiographic features on the visual outcome of patients with myopic sub-foveal choroidal neovascularization (CNV) who received photodynamic therapy (PDT). METHODS: Thirty-six consecutive patients (39 eyes) with myopic CNV who were followed up for more than one year after PDT were enrolled in this study. Clinical features included age, gender, refractive error, great linear dimension, and subretinal hemorrhage. ICG features included the lesion size, lacquer cracks, hypofluorescence surrounding the CNV (dark rim), peripapillary atrophy size, and visible prominent choroidal veins under the macula. Linear regression analysis was performed using the change in visual acuity (delta logMAR) as the dependent variable and the above factors as independent variables. RESULTS: At one-year follow-up after PDT, a younger age (p = 0.002) and the presence of a dark rim (p = 0.002) were significantly correlated with an improvement of visual acuity (decrement in logMAR) after PDT. Other factors had no significant influence on changes in visual acuity. CONCLUSIONS: Younger patients and patients with a dark rim on ICG angiography had a higher chance of visual improvement after PDT in myopic CNV.     

The farnesyltransferase inhibitor, LB42708, inhibits growth and induces apoptosis irreversibly in H-ras and K-ras-transformed rat intestinal epithelial cells

LB42708 (LB7) and LB42908 (LB9) are pyrrole-based orally active farnesyltransferase inhibitors (FTIs) that have similar structures. The in vitro potencies of these compounds against FTase and GGTase I are remarkably similar, and yet they display different activity in apoptosis induction and morphological reversion of ras-transformed rat intestinal epithelial (RIE) cells. Both FTIs induced cell death despite K-ras prenylation, implying the participation of Ras-independent mechanism(s). Growth inhibition by these two FTIs was accompanied by G1 and G2/M cell cycle arrests in H-ras and K-ras-transformed RIE cells, respectively. We identified three key markers, p21(CIP1/WAF1), RhoB and EGFR, that can explain the differences in the molecular mechanism of action between two FTIs. Only LB7 induced the upregulation of p21(CIP1/WAF1) and RhoB above the basal level that led to the cell cycle arrest and to distinct morphological alterations of ras-transformed RIE cells. Both FTIs successfully inhibited the ERK and activated JNK in RIE/K-ras cells. While the addition of conditioned medium from RIE/K-ras reversed the growth inhibition of ras-transformed RIE cells by LB9, it failed to overcome the growth inhibitory effect of LB7 in both H-ras- and K-ras-transformed RIE cells. We found that LB7, but not LB9, decreased the expression of EGFRs that confers the cellular unresponsiveness to EGFR ligands. These results suggest that LB7 causes the induction of p21(CIP1/WAF1) and RhoB and downregulation of EGFR that may serve as critical steps in the mechanism by which FTIs trigger irreversible inhibitions on the cell growth and apoptosis in ras-transformed cells.     

Medicinal plants as potential sources of lead compounds with anti-platelet and anti-coagulant activities

Medicinal plants are potential sources of lead compounds which can be further developed or optimised into novel therapeutics. This paper gives an overview of drug discovery from plants and an up-to-date and comprehensive review of plants and phytoconstituents reported to have anti-platelet and anti-coagulant activities.