Mechanism of salinity tolerance in plants: physiological, biochemical, and molecular characterization

Salinity is a major abiotic stress limiting growth and productivity of plants in many areas of the world due to increasing use of poor quality of water for irrigation and soil salinization. Plant adaptation or tolerance to salinity stress involves complex physiological traits, metabolic pathways, and molecular or gene networks. A comprehensive understanding on how plants respond to salinity stress at different levels and an integrated approach of combining molecular tools with physiological and biochemical techniques are imperative for the development of salt-tolerant varieties of plants in salt-affected areas. Recent research has identified various adaptive responses to salinity stress at molecular, cellular, metabolic, and physiological levels, although mechanisms underlying salinity tolerance are far from being completely understood. This paper provides a comprehensive review of major research advances on biochemical, physiological, and molecular mechanisms regulating plant adaptation and tolerance to salinity stress.

Prevalence of diabetic retinopathy in various ethnic groups: a worldwide perspective

The alarming rise in diabetes prevalence is a global public health and economic problem. Diabetic retinopathy is the most common complication of diabetes and the leading cause of blindness among working-age populations in the Western world. Screening and prompt treatment of diabetic retinopathy are not top priorities in many regions of the world, because the impacts of other causes of preventable blindness remain an issue. Ethnicity is a complex, independent risk factor for diabetic retinopathy. Observations from white populations cannot be extrapolated fully to other ethnic groups. The prevalence of diabetic retinopathy, sight-threatening diabetic retinopathy, and clinically significant macular edema are higher in people of South Asian, African, Latin American, and indigenous tribal descent compared to the white population. Although all ethnic groups are susceptible to the established risk factors of diabetic retinopathy-such as length of exposure and severity of hyperglycemia, hypertension, and hyperlipidemia-ethnic-specific risk factors also may influence these rates. Such risk factors may include differential susceptibility to conventional risk factors, insulin resistance, differences in anthropometric measurements, truncal obesity, urbanization, variations in access to healthcare systems, genetic susceptibility, and epigenetics. The rates of nonproliferative diabetic retinopathy appear to be declining in the United States, supporting the observation that better medical management of diabetes and prompt treatment of sight-threatening diabetic retinopathy substantially improve the long-term diabetic retinopathy incidence; studies from other parts of the world are limited and do not mirror this finding, however. We examine the ethnicity and region-based prevalence of diabetic retinopathy around the world and highlight the need to reinforce ethnicity-based screening and treatment thresholds in diabetic retinopathy.

Predicting visual success in macular hole surgery

AIM

Data on the outcome of surgery facilitate informed preoperative patient counselling. Most studies on the outcome of surgery for idiopathic full thickness macular hole surgery have concentrated on rates of anatomical closure. The aim of this study was to identify factors predicting visual success (better than 20/40; 6/12 Snellen) following macular hole surgery.

METHODS

A retrospective study of 133 patients undergoing standardised macular hole surgery with at least 3 months of postoperative follow-up. All patients underwent preoperative measurement of the maximum macular hole diameter using optical coherence tomography.

RESULTS

Multivariable regression analysis identified that age, preoperative visual acuity and macular hole size were significant predictors of visual success. The resulting model correctly classified the visual outcome of 80% of cases. Predicted rates of visual success varied from 93% in patients <60 years old with visual acuity better than 6/24 and a hole diameter of <350 mum, to 2% in patients those >79 years old with visual acuity of 6/60 or worse and hole diameter of >500 microm.

CONCLUSION

The results provide a simple and clinically useful model to employ when counselling patients on macular hole surgery.

Peritonitis associated with exit site and tunnel infections

We reviewed all episodes of peritonitis associated with exit site and/or tunnel infection (n = 87; rate, 0.1/yr; 13% of all peritonitis episodes) occurring from 1979 to 1995. The exit site or tunnel infection was diagnosed at the time or shortly after the patient presented with peritonitis in 66% of the episodes. In the other one third the exit site or tunnel infection was diagnosed a median of 40 days prior to the development of peritonitis. Staphylococcus aureus accounted for 52% of episodes. Pseudomonas aeruginosa was the next most common organism. In 63 (72%) of the episodes the catheter was removed to resolve the infection at a median of 8 days (range, 0 to 226 days) from the onset of peritonitis. Catheter removal after 5 days predominately for refractory peritonitis (n = 23; median time to removal, 8 days) or relapsing peritonitis (n = 11; median time to catheter removal, 103 days). Patients with relapsing peritonitis suffered two to four episodes prior to removal of the catheter. Patients with peritonitis associated with tunnel infection were more likely to lose their catheter than patients with peritonitis associated with exit site infection (86% v 58%), while Staphylococcus epidermidis infections were less likely to result in catheter loss compared with all other organisms (15% v 82%). After a protocol to reduce S aureus catheter infections was implemented in 1990, the rate of catheter-related peritonitis decreased from 0.14/yr to 0.05/yr due to a decrease in S aureus episodes. We conclude that peritonitis episodes associated with a tunnel infection infrequently resolve without catheter removal. Delayed catheter removal in such circumstances often results in refractory or relapsing peritonitis. Therefore, catheter removal should be done promptly. Antibiotic prophylaxis for S aureus can reduce catheter-related peritonitis.

Curcuma longa inhibits TNF-alpha induced expression of adhesion molecules on human umbilical vein endothelial cells

Identification of non-steroidal anti-inflammatory small molecules is very important for the development of anti-inflammatory drugs. We demonstrate here that out of three compounds, viz diferuloylmethane, p-coumaroylferuloylmethane and di-p-coumaroylmethane, present in the ethyl acetate extract of Curcuma longa, diferuloylmethane is most potent in inhibiting TNF-alpha induced expression of ICAM-1, VCAM-1 and E-selectin on human umbilical vein endothelial cells. The inhibition by diferuloylmethane is time dependent and is reversible. By using RT-PCR, we demonstrate that it inhibits the induction of steady state transcript levels of ICAM-1, VCAM-1 and E-selectin, and therefore it may interfere with the transcription of their genes. As diferuloylmethane significantly blocks the cytokine induced transcript levels for the leukocyte adhesion molecules, it may be interfering at an early stage of signalling event induced by TNF-alpha.

Anti-tubercular therapy for intraocular tuberculosis: A systematic review and meta-analysis

Intraocular tuberculosis remains a diagnostic and management conundrum for both ophthalmologists and pulmonologists. We analyze the efficacy and safety of anti-tubercular therapy (ATT) in patients with intraocular tuberculosis and factors associated with favorable outcome. Twenty-eight studies are included in this review, with a total of 1,917 patients. Nonrecurrence of inflammation was observed in pooled estimate of 84% of ATT-treated patients (95% CI 79-89). There was minimal difference in the outcome between patients treated with ATT alone (85% successful outcome; 95% CI 25-100) and those with concomitant systemic corticosteroid (82%; 95% CI 73-90). The use of ATT may be of benefit to patients with suspected intraocular tuberculosis; however, this conclusion is limited by the lack of control group analysis and standardized recruitment and treatment protocols. We propose further prospective studies to better establish the efficacy of ATT and ascertain the factors associated with favorable treatment outcomes.

Hydrogen Peroxide and Polyamines Act as Double Edged Swords in Plant Abiotic Stress Responses

The specific genetic changes through which plants adapt to the multitude of environmental stresses are possible because of the molecular regulations in the system. These intricate regulatory mechanisms once unveiled will surely raise interesting questions. Polyamines and hydrogen peroxide have been suggested to be important signaling molecules during biotic and abiotic stresses. Hydrogen peroxide plays a versatile role from orchestrating physiological processes to stress response. It helps to achieve acclimatization and tolerance to stress by coordinating intra-cellular and systemic signaling systems. Polyamines, on the other hand, are low molecular weight polycationic aliphatic amines, which have been implicated in various stress responses. It is quite interesting to note that both hydrogen peroxide and polyamines have a fine line of inter-relation between them since the catabolic pathways of the latter releases hydrogen peroxide. In this review we have tried to illustrate the roles and their multifaceted functions of these two important signaling molecules based on current literature. This review also highlights the fact that over accumulation of hydrogen peroxide and polyamines can be detrimental for plant cells leading to toxicity and pre-mature cell death.

Intracranial pressure during nitroglycerin-induced hypotension

Nitroglycerin was given intravenously to five anesthetized, hyperventilated (PaCO2 25 to 30 torr) patients during craniotomy, to facilitate surgery by creating a relatively bloodless field, and to decrease the potential need to blood transfusion. A subarachnoid screw and an indwelling radial artery catheter were inserted to monitor intracranial pressure (ICP) and mean arterial pressure (MAP). As MAP decreased from 10.4 +/- 4.0 (SE) to 69.0 +/- 1.8 torr, ICP increased from 14.2 +/- 0.7 (SEM) to 30.8 +/- 1.1 torr. Cerebral perfusion pressure decreased from 90.2 +/- 3.6 (SEM) to 38.2 +/- 2.3 torr (p < 0.0005). We attribute this nitroglycerin-induced ICP increase to capacitance vessel dilation within the relatively noncompliant cranial cavity, with subsequent cerebral blood volume increase.

An ABRE-binding factor, OSBZ8, is highly expressed in salt tolerant cultivars than in salt sensitive cultivars of indica rice

BACKGROUND

The bZIP class Abscisic acid Responsive Element (ABRE)-binding factor, OSBZ8 (38.5 kD) has been considered to regulate ABA-mediated transcription in the suspension cultured cells of japonica rice. Still, nothing is known about the expression of OSBZ8 at protein level in vegetative tissue of salt sensitive and salt tolerant rice plants. In our previous study, Electrophoretic Mobility Shift Assay (EMSA) of [32P]ABRE-DNA and nuclear extracts prepared from the lamina of Pokkali rice plants has detected the presence of an ABRE-binding factor. Northern analysis has also detected salinity stress induced accumulation of transcripts for bZIP class of factor. Therefore, OSBZ8 was considered to play an important role in the regulation of transcription in the vegetative tissue of rice. The aim of this study is to find out whether OSBZ8 has any role in regulating the NaCl-stress induced gene expression in vegetative tissue and whether the expression of OSBZ8 factor directly correlates with the stress tolerance of different varieties of indica type rice.

RESULTS

Northern analysis of total RNA from roots and lamina of salt-sensitive M-I-48 and salt-tolerant Nonabokra, when probed with the N-terminal unique region of OSBZ8 (OSBZ8p, without the highly conserved basic region), a transcript of 1.3 kb hybridized and its level was much higher in tolerant cultivar. EMSA with Em1a, the strongest ABA Responsive Element till reported from the upstream of EmBP1, and the nuclear extracts from laminar tissue of untreated and salt-treated seedlings of three salt sensitive, one moderately sensitive and two salt tolerant indica rice cultivars showed specific binding of nuclear factor to ABRE element. Intensity of binding was low and inducible in salt sensitive rice cultivars while high and constitutive in salt tolerant cultivars. EMSA with 300 bp 5'upstream region of Rab16A gene, a well known salt stress and ABA-inducible gene of rice, showed formation of two complexes, again very weak in salt sensitive and strong in salt tolerant rice cultivar.

CONCLUSION

The bZIP factor OSBZ8 was found to be present in the ABRE-DNA: protein complex as shown by the supershift of the complex by the purified antiserum raised against OSBZ8p. Treatment of the seedlings with NaCl was found to enhance the complex formation, suggesting the regulation of OSBZ8 gene at both transcriptional and post-translational steps. Comparative EMSA with different varieties of rice suggests a positive correlation with the expression pattern of OSBZ8 and salt tolerance in rice cultivars.

Anti-inflammatory effect of Ruta graveolens L. in murine macrophage cells

Ruta graveolens L. (Rutaceae) is used for several therapeutic purposes worldwide. The present study is designed to investigate the effect of plant extract of Ruta graveolens on murine macrophage cells (J-774) challenged with lipopolysaccharide (LPS). LPS induces inflammatory response by stimulating the production of nitric oxide and other mediators. Significant inhibition (p=0.01 to p<0.002) of the LPS-induced nitric oxide production was observed in cells treated with plant extract in a concentration dependent manner. The inhibition observed for the extract was significantly higher than that observed for rutin, a flavonoid constituent of the plant. At 40 microM rutin, a comparable concentration of this flavonoid in the highest concentration (500 microg/ml) of plant extract was used in this study; a 20% inhibition (p=0.058) was observed. Inhibition in inducible nitric oxide synthase (inos) gene expression in the cells treated with the plant extract suggests an inhibition at the transcription level. Interestingly, a concomitant decrease in transcription of cyclooxygenase-2 (COX-2) gene has also been observed in cells treated with the plant extract and this inhibition is significantly higher than that observed with the highest concentration of rutin (80 microM) used in the study. As an inflammatory response, upregulation of nitric oxide synthase (iNOS) and COX-2 enzymes leads to production of pro-inflammatory mediators, namely nitric oxide and prostaglandins, respectively. Hence, the significant inhibitory effects on both of these inflammatory mediators unravel a novel anti-inflammatory action of this plant.

The attitudes of undergraduate students and staff to the use of electronic learning

BACKGROUND

Computer-aided learning (CAL) offers advantages over traditional methods of learning as it allows students to work in their own time and pace. The School of Dentistry at the University of Birmingham has created an electronic learning website, named the Ecourse. This is designed to be a web-based supplement to the dental undergraduate curriculum.

AIM

The aim of this study was to determine the attitudes of third year dental students and members of staff about the Ecourse website.

METHOD

A questionnaire was produced and piloted before being distributed to all 65 third year dental students to obtain their opinions about the Ecourse website. The views of Ecourse were sought from four members of staff by performing qualitative, semi-structured interviews.

RESULTS

Lecture handouts and textbooks were reported as the sources used most often, by 96% of students. Eighty-six per cent of students are accessing the Ecourse mainly at the School of Dentistry, but 53% are also accessing it at home. Students liked the multiple-choice questions, downloading extra notes and looking at pictures and animation to explain clinical procedures. The majority of the students (79%) want the Ecourse to be used as a supplement to the undergraduate programme and 7% wanted it to replace formal lectures. Staff recognised the benefits of the Ecourse but were concerned about plagiarism, the effect on lecture attendance and the lack of feedback from students on existing CAL material.

CONCLUSION

Students consider the Ecourse as a positive method of supplementing traditional methods of learning in the dental undergraduate programme. However in contrast teaching staff expressed negative views on the use of e-learning.

Effect of Scalp Block on Postoperative Pain Relief in Craniotomy Patients

The efficacy of scalp nerve block using 0.5% bupivacaine with adrenaline for postoperative pain relief in craniotomy patients was evaluated in 40 ASA I or II adult patients undergoing supratentorial craniotomy. A standard general anaesthesia technique was followed. Patients were randomly divided into two groups. Group B received 0.5% bupivacaine with 1:400,000 adrenaline and group S received normal saline with 1:400,000 adrenaline, both after skin closure. Postoperative pain was assessed at 30 seconds and 1, 2, 4, 6, 8 and 12 hours using a numerical rating scale. Diclofenac IM was administered as rescue analgesia if patients reported a numerical rating scale of 40 or more. Tramadol TV was administered as second rescue analgesia. Sixty per cent of patients in group S experienced moderate to severe pain (numerical rating scale of 40 or more) at some time during the first 12 postoperative hours in comparison to 25% patients in group B. Median pain scores were significantly lower in group B for up to 6 hours. Significantly more patients were pain free up to four hours in group B. Median duration for the requirement of first dose of diclofenac was longer in group B compared to group S (360 min vs 30 min, P<0.01). The number of doses of diclofenac (5 vs 19) was significantly lower in group B compared to group S (P<0.01). Tramadol was required by six patients in group S only. Scalp nerve block using 0.5% bupivacaine with 1:400,000 adrenaline decreases the incidence and severity of postoperative pain in patients undergoing supratentorial craniotomy.

The Collaborative Ocular Tuberculosis Study (COTS)-1 Report 3: Polymerase Chain Reaction in the Diagnosis and Management of Tubercular Uveitis: Global Trends

Purpose: To analyze the role of polymerase chain reaction (PCR) of ocular fluids in management of tubercular (TB) anterior, intermediate, posterior, and panuveitis. Methods: In Collaborative Ocular Tuberculosis Study (COTS)-1 (25 centers, n = 962), patients with TB-related uveitis were included. 59 patients undergoing PCR of intraocular fluids (18 females; 53 Asian Indians) were included. Results: 59 (6.13%) of COTS-1 underwent PCR analysis. PCR was positive for Mycobacterium TB in 33 patients (23 males; all Asian Indians). 26 patients were PCR negative (18 males). Eight patients with negative PCR had systemic TB. Anti-TB therapy was given in 18 negative and 31 PCR cases. At 1-year follow-up, five patients with positive PCR (15.15%) and three with negative PCR (11.54%) had persistence/worsening of inflammation. Conclusions: Data from COTS-1 suggest that PCR is not commonly done for diagnosing intraocular TB and positive/negative results may not influence management or treatment outcomes in the real world scenario.

Measurement of PO2 during vitrectomy for central retinal vein occlusion, a pilot study

INTRODUCTION

In this pilot study the effects of vitrectomy on PO(2) in the vitreous cavity in CRVO were investigated.

STUDY DESIGN

Prospective, controlled, interventional study.

METHOD

Six patients with ischaemic CRVO in one eye (undergoing vitrectomy for radial optic neurotomy, RON) and six with either macula hole or membrane were included. An oxygen probe was inserted before removal of the vitreous (pre-vitrectomy) and after removal of the vitreous (post-vitrectomy). In the patients with CRVO, measurements were taken before RON was performed. Oxygenation recordings (PO(2)) were taken in the mid-vitreous cavity and the preretinal vitreous.

RESULTS

Mean age was 65 years. In controls, pre-vitrectomy, the mean PO(2) adjacent to the retina (15.0 mmHg S.D.5.7) was significantly less than mid-cavity (33.7 mmHg S.D.12.8). Similarly in CRVO, the pre-vitrectomy pre-retinal PO(2) (8.1 mmHg S.D. 3.5), was significantly less than mid-cavity (19.8 mmHg S.D.7.3). The mean PO(2) was significantly less in the eyes with CRVO than in control eyes. Post-vitrectomy, the PO(2) was significantly greater than pre-vitrectomy at both recording sites in the controls mid-cavity (61.5 mmHg S.D.13.9) and pre-retinal (75.8 mmHg S.D. 9.1), and CRVO eyes mid-cavity (53.7 mmHg S.D. 17.9) and pre-retinal (59.8 mmHg S.D. 15.8).

CONCLUSION

PO(2) is reduced in the vitreous cavity in CRVO. Vitrectomy may be a method of increasing oxygen availability to the retina.

Symmetrical peripheral gangrene

Symmetrical peripheral gangrene (SPG), seen in a wide variety of medical conditions presents as symmetrical gangrene of two or more extremities without large vessel obstruction or vasculitis. Fingers, and toes (rarely nose, ear lobes or genitilia) are affected. It may manifest unpredictably in conditions associated with sepsis, low output states, vasospastic conditions, myeloproliferative disorders or in hyperviscosity syndrome. It carries a high mortality rate with a very high frequency of multiple limb amputations in survivors. Disseminated intravascular coagulation (DIC) is seen in majority of cases of SPG. A more or less stereotyped clinical picture of SPG in spite of ever widening aetiological spectrum is suggestive of DIC as the final common pathway of its pathogenesis. Early recognition of acrocyanosis, quick reversal of DIC, effective management of the underlying condition, haemodynamic stabilization and (perhaps) anticoagulation with low dose heparin (300-500 iu/hour) may be helpful in arresting the progression of pre-gangrenous changes to frank gangrene. Vasopressors such as dopamine should be used judiciously in the presence of DIC. Development of acrocyanosis and increase in serum lactate levels may be indicative of impending SPG and the imperative need to treat DIC as well as the underlying condition.

Development of the Drosophila olfactory sense organs utilizes cell-cell interactions as well as lineage

We have examined the mechanisms underlying the development of the olfactory sense organs on the third segment of the antenna of Drosophila. Our studies suggest that a novel developmental strategy is employed. Specification of the founder or precursor cell is not governed by the genes of the achaete-scute complex. Another basic helix-loop-helix encoding gene, atonal, is essential for determination of only a subset of the sensilla types--the sensilla coeloconica. Therefore, we predict the existence of additional proneural genes for the selection of sensilla trichoidea and sensilla basiconica. The choice of a founder cell from the presumed proneural domain is regulated by Notch activity. Soon after delamination of the founder cell, two to three additional neighboring cells also take on a sensory fate and these cells together form a presensillum cluster. The selection of neighbors does not occur when endocytosis is blocked using a temperature sensitive allele of shibire, thus suggesting that cell-cell communication is required for this step. The cells of the cluster divide once before terminal differentiation which is influenced by Notch activity. The final cell number within each sensillum is controlled by programmed cell death.