Essentiality of mitochondrial oxidative metabolism for photosynthesis: optimization of carbon assimilation and protection against photoinhibition

The review emphasizes the essentiality of mitochondrial oxidative metabolism for photosynthetic carbon assimilation. Photosynthetic activity in chloroplasts and oxidative metabolism in mitochondria interact with each other and stimulate their activities. During light, the partially modified TCA cycle supplies oxoglutarate to cytosol and chloroplasts. The marked stimulation of O2 uptake after few minutes of photosynthetic activity, termed as light enhanced dark respiration (LEDR), is now a well-known phenomenon. Both the cytochrome and alternative pathways of mitochondrial electron transport are important in such interactions. The function of chloroplast is optimized by the complementary nature of mitochondrial metabolism in multiple ways: facilitation of export of excess reduced equivalents from chloroplasts, shortening of photosynthetic induction, maintenance of photorespiratory activity, and supply of ATP for sucrose biosynthesis as well as other cytosolic needs. Further, the mitochondrial oxidative electron transport and phosphorylation also protects chloroplasts against photoinhibition. Besides mitochondrial respiration, reducing equivalents (and ATP) are used for other metabolic phenomena, such as sulfur or nitrogen metabolism and photorespiration. These reactions often involve peroxisomes and cytosol. The beneficial interaction between chloroplasts and mitochondria therefore extends invariably to also peroxisomes and cytosol. While the interorganelle exchange of metabolites is the known basis of such interaction, further experiments are warranted to identify other biochemical signals between them. The uses of techniques such as on-line mass spectrometric measurement, novel mutants/transgenics, and variability in metabolism by growth conditions hold a high promise to help the plant biologist to understand this interesting topic

Effectiveness of prenatal teaching on prevention of breast engorgement

Background: Breast engorgement is a major issue in the early postpartum period under the influence of hormonal shift and increase milk production. The purpose of this study was to evaluate the prevention, recognition and management of breast engorgement.Methods: Quasi Experimental, quantitative study conducted in AIMS, Kochi among sixty mothers by Convenience sampling technique. The design used was pre-test post-test control group design. A semi structured knowledge questionnaire, Bristol Breastfeeding Assessment Tool and an Observational checklist were used to collect the data. Prenatal teaching provided to the Experimental group.Results: The mean pre-test knowledge level of control group was 9.83 and the post-test knowledge was 10.03. In the Experimental group, the mean pre-test level was 10.20 and the post-test level is 20.76. The ‘t’ value of control group was 0.71 and that of Experimental group was 12.83 which was highly significant at 0.001 level. There was a significant increase in knowledge score in Experimental group. Comparing the breastfeeding practices regarding positioning and attachment in both groups, showed a significant difference at the level of 0.001 but other two aspects, sucking and swallowing were not significant. Comparing the incidence, 13.3% mothers reported in experimental group whereas 63.3% in the control group, which showed a remarkable decrease in the incidence of breast engorgement in the former group.Conclusions: The prenatal teaching was effective in improving the health of mothers as well as practices of breastfeeding and it helped in reduction of the incidence of breast engorgement

THERAPEUTIC EFFECTS AND ADVERSE EVENTS OF SINGLE DOSE OF INTRAVITREAL TRIAMCINOLONE ACETONIDE INJECTION IN MACULAR EDEMA

Objective: The objective of the study was to study the therapeutic effects and adverse events of single dose of intravitreal triamcinolone acetonide (TA) in macular edema (ME). Methods: This prospective observational study was conducted for a period of 18 months in a tertiary care hospital. A total of 100 patients who received intravitreal injection of TA 4 mg were followed up within 1 month of injection and thereafter monthly for 3 months. Therapeutic effect was noted by improvement in visual acuity and reduction in macular thickness. Safety was assessed based on adverse events reported during the study period. The quantitative variables were analyzed by paired t-test and the qualitative variables by Wilcoxon signed-rank test and Chi-square test. Results: The mean age was 58.66±11.21 years with majority of patients (46%) in 46–60 age group. Diabetic retinopathy was the most common etiology. Fifteen patients experienced improvement in vision within 1 month, 51, 84, and 91 patients had better visual acuity after 1, 2, and 3 months, respectively, which were statistically significant (p=0.001). The mean macular thickness of 497.79±115.08 at baseline reduced to 448.62±112.48 within 1 month which further reduced to 383.72±105.79, 327.33±86.49, and 263.83±68.68 at the end of the 1st, 2nd, and 3rd months, respectively (p=0.001). The adverse events of rise in intraocular pressure, cataract, redness, pain, floaters, and subconjunctival hemorrhage were not found to be statistically significant (p>0.05). Conclusion: Intravitreal TA injection may be an effective and safe treatment option for ME due to various etiologies

From Medley to Magnificence: Developing Problem Solving Skills in Biochemistry

Background: Medical students need problem-solving skills because these are crucial in diagnosing cases in the future. This study aimed to improve medical students’ problemsolving abilities through analysis, reasoning, and application. Methods: A four-month prospective cross-sectional study was conducted at MNR Medical College and Hospital (March to June 2021). Six case scenarios were developed and created in PowerPoint. Each scenario was broken down into the following sections: title, history, clinical findings, investigations, and treatment. The slides were arranged randomly to produce a medley which was then shown to the students. They were tasked with sorting the slides and diagnosing each case. Student responses were gathered using a Google Forms questionnaire. Results: The number of participants who completed the activity within the stipulated time was 132. The majority of students (85%) scored over 80% in the activity. The activity was interesting (63.6%), promoted active learning (65.2%), helped students correlate the different aspects of the case scenario and make a diagnosis (69.7%), helped build problembased skills, and activated prior knowledge (71.2%), improved clinical orientation to the curriculum (65.2%), exposed students to aspects of the diseases not dealt with in the classroom (40.9%), students felt such an activity should be required of future students (68.2%). Conclusion: This novel learning method of integrating case scenarios using a digital platform provided multiple opportunities for testing and developing skills necessary for clinical practice. The fact that the activity was well received by students strengthens the argument to create additional activities of this type that may be applied to any topic

Importance of ROS and antioxidant system during the beneficial interactions of mitochondrial metabolism with photosynthetic carbon assimilation

The present study suggests the importance of reactive oxygen species (ROS) and antioxidant metabolites as biochemical signals during the beneficial interactions of mitochondrial metabolism with photosynthetic carbon assimilation at saturating light and optimal CO2. Changes in steady-state photosynthesis of pea mesophyll protoplasts monitored in the presence of antimycin A [AA, inhibitor of cytochrome oxidase (COX) pathway] and salicylhydroxamic acid [SHAM, inhibitor of alternative oxidase (AOX) pathway] were correlated with total cellular ROS and its scavenging system. Along with superoxide dismutase (SOD) and catalase (CAT), responses of enzymatic components-ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), glutathione reductase (GR) and non-enzymatic redox components of ascorbate-glutathione (Asc-GSH) cycle, which play a significant role in scavenging cellular ROS, were examined in the presence of mitochondrial inhibitors. Both AA and SHAM caused marked reduction in photosynthetic carbon assimilation with concomitant rise in total cellular ROS. Restriction of electron transport through COX or AOX pathway had differential effect on ROS generating (SOD), ROS scavenging (CAT and APX) and antioxidant (Asc and GSH) regenerating (MDAR and GR) enzymes. Further, restriction of mitochondrial electron transport decreased redox ratios of both Asc and GSH. However, while decrease in redox ratio of Asc was more prominent in the presence of SHAM in light compared with dark, decrease in redox ratio of GSH was similar in both dark and light. These results suggest that the maintenance of cellular ROS at optimal levels is a prerequisite to sustain high photosynthetic rates which in turn is regulated by respiratory capacities of COX and AOX pathways

Microbiological Spectrum of Brain Abscess at a Tertiary Care Hospital in South India: 24-Year Data and Review

Intracranial abscesses are life-threatening infections that pose a diagnostic challenge not only to the neurosurgeon but also to the microbiologists. Detailed studies documenting the spectrum of infecting agents involved in brain abscesses are limited from India. Materials and Methods. This is a retrospective analysis of 352 samples from 1987 to 2010 analyzed at a tertiary care hospital in South India from 1987 to 2010, to document the changing trends with time. Results. The age of the patients ranged from 2 to 80 years, a larger number of males being affected. Otogenic infections were the most common cause while cryptogenic abscesses were 20%. Gram stain and culture positivity were 78% each. Gram-positive and negative facultative aerobes and obligate anaerobes were also on the rise. Unusual organisms, like Burkholderia pseudomallei, Salmonella typhi, Nocardia species, Cladosporium bantiana, Fonsecaea pedrosoi, Entamoeba histolytica, and Acanthamoeba were also isolated and/or detected from the brain abscesses aspirate or resected tissue. Summary. New and emerging pathogens associated with brain abscess, especially in immunosuppressed individuals, have renewed the necessity of an early detection, and it will be of great value in appropriate management of patients with brain abscess

Utility of the modified ATP III defined metabolic syndrome and severe obesity as predictors of insulin resistance in overweight children and adolescents: a cross-sectional study

BACKGROUND: The rising prevalence of obesity and metabolic syndrome (MetS) has received increased attention since both place individuals at risk for Type II diabetes and cardiovascular disease. Insulin resistance (IR) has been implicated in the pathogenesis of obesity and MetS in both children and adults and is a known independent cardiovascular risk factor. However measures of IR are not routinely performed in children while MetS or severe obesity when present, are considered as clinical markers for IR. OBJECTIVE: The study was undertaken to assess the utility of ATPIII defined metabolic syndrome (MetS) and severe obesity as predictors of insulin resistance (IR) in a group of 576 overweight children and adolescents attending a pediatric obesity clinic in Brooklyn. METHODS: Inclusion criteria were children ages 3–19, and body mass index > 95th percentile for age. MetS was defined using ATP III criteria, modified for age. IR was defined as upper tertile of homeostasis model assessment (HOMA) within 3 age groups (3–8, n = 122; 9–11, n = 164; 12–19, n = 290). Sensitivity, specificity, positive predictive values and odds ratios (OR) with 95% confidence intervals (CI) were calculated within age groups for predicting IR using MetS and severe obesity respectively. RESULTS: MetS was present in 45%, 48% and 42% of the respective age groups and significantly predicted IR only in the oldest group (OR = 2.0, 95% CI 1.2, 3.4; p = .006). Sensitivities were <55%; specificities <63% and positive predictive values ≤ 42% in all groups. Severe obesity was significantly associated with IR in both the 9–11 (p = .002) and 12–18 (p = .01) groups but positive predictive values were nonetheless ≤ 51% for all groups. CONCLUSION: The expression of IR in overweight children and adolescents is heterogeneous and MetS or severe obesity may not be sufficiently sensitive and specific indicators of insulin resistance. In addition to screening for MetS in overweight children markers for IR should be routinely performed. Further research is needed to establish threshold values of insulin measures in overweight children who may be at greater associated risk of adverse outcomes whether or not MetS is present

Biochemical properties of a bacterially-expressed Bowman-Birk inhibitor from Rhynchosia sublobata (Schumach.) Meikle seeds and its activity against gut proteases of Achaea janata

Crude proteinase inhibitors (CPIs) extracted from the seeds of Rhynchosia sublobata, a wild relative of pigeon pea showed pronounced inhibitory activity on the larval gut trypsin-like proteases of lepidopteran insect pest – Achaea janata. Consequently, a full-length cDNA of Bowman-Birk inhibitor gene (RsBBI1) was cloned from the immature seeds of R. sublobata. It contained an ORF of 360 bp encoding a 119-amino acid polypeptide (13.3 kDa) chain with an N-terminus signal sequence comprising of 22 amino acids. The amino acid sequence and phylogenetic analysis together revealed that RsBBI1 exhibited a close relation with BBIs from soybean and Phaseolus spp. A cDNA sequence corresponding to RsBBI1 mature protein (89 amino acid stretch) was expressed in E. coli. The recombinant rRsBBI1 protein with a molecular mass of 9.97 kDa was purified using trypsin affinity chromatography. The purified rRsBBI1 exhibited non-competitive mode of inhibition of both bovine trypsin (Ki of 358 ± 11 nM) and chymotrypsin (Ki of 446 ± 9 nM). Its inhibitory activity against these proteases was stable at high temperatures (>95 °C) and a wide pH range but sensitive to reduction with dithiothreitol (DTT), indicating the importance of disulphide bridges in exhibiting its activity. Also, rRsBBI1 showed significant inhibitory activity (IC50 = 70 ng) on A. janata larval gut trypsin-like proteases (AjGPs). Conversely, it showed <1% inhibitory activity (IC50 = 8 μg) on H. armigera larval gut trypsin-like proteases (HaGPs) than it has against AjGPs. Besides, in vivo feeding experiments clearly indicated the deleterious effects of rRsBBI1 on larval growth and development in A. janata which suggests it can be further exploited for such properties

Photosynthetic Adaptation to Length of Day Is Dependent on S-Sulfocysteine Synthase Activity in the Thylakoid Lumen

Abstract Arabidopsis (Arabidopsis thaliana) chloroplasts contain two O-acetyl-serine(thiol)lyase (OASTL) homologs, OAS-B, which is an authentic OASTL, and CS26, which has S-sulfocysteine synthase activity. In contrast with OAS-B, the loss of CS26 function resulted in dramatic phenotypic changes, which were dependent on the light treatment. We have performed a detailed characterization of the photosynthetic and chlorophyll fluorescence parameters in cs26 plants compared with those of wild-type plants under short-day growth conditions (SD) and long-day growth conditions (LD). Under LD, the photosynthetic characterization, which was based on substomatal CO2 concentrations and CO2 concentration in the chloroplast curves, revealed significant reductions in most of the photosynthetic parameters for cs26, which were unchanged under SD. These parameters included net CO2 assimilation rate, mesophyll conductance, and mitochondrial respiration at darkness. The analysis also showed that cs26 under LD required more absorbed quanta per driven electron flux and fixed CO2. The nonphotochemical quenching values suggested that in cs26 plants, the excess electrons that are not used in photochemical reactions may form reactive oxygen species. A photoinhibitory effect was confirmed by the background fluorescence signal values under LD and SD, which were higher in young leaves compared with mature ones under SD. To hypothesize the role of CS26 in relation to the photosynthetic machinery, we addressed its location inside of the chloroplast. The activity determination and localization analyses that were performed using immunoblotting indicated the presence of an active CS26 enzyme exclusively in the thylakoid lumen. This finding was reinforced by the observation of marked alterations in many lumenal proteins in the cs26 mutant compared with the wild type.</jats:p