Studies on the interaction of hematoporphyrin with hemoglobin

Spectrophotometric and spectrofluorimetric studies reveal that an interaction occurs between hemoglobin and hematoporphyrin, a photosensitizing drug used in photodynamic therapy. Two concentration ranges of hematoporphyrin, 0.4-0.9 microM and 1.8-3.6 microM, representing significantly monomeric and aggregated (dimeric) state, respectively, have been used in the binding studies. The binding affinity constant (K) decreases, while the possible number of binding sites (p) increases as the concentration range of the porphyrin is increased. The nature of interaction has been studied by fluorescence quenching titration method under different ionic strengths and temperature conditions. It appears to be predominantly electrostatic and enthalpy-driven in the lower range of porphyrin concentration. However, the interaction follows mostly hydrophobic and entropy-driven modality in the higher concentration range of the ligand. The porphyrin-hemoglobin interaction results in release of oxygen from the protein. The extent of oxygen release depends on the stoichiometric ratio of hematoporphyrin:hemoglobin.

A, Kingston J, Singh UK. Detection and classification of Bacteria using Raman Spectroscopy Combined with Multivariate Analysis

<p class="p1">Vibrational spectroscopic techniques have advantages over conventional microbiological approaches towards identification &amp; detection of pathogens. Since unique spectral fingerprint is obtained, one can identify very closely related bacteria using such methods. In this study Raman microspectroscopy in combination with chemometric method has been used to classify four strains of <em>E</em>. <em>coli </em>(two pathogenic &amp; two non-pathogenic). Different multivariate approaches such as hierarchical cluster analysis, principal component analysis &amp; linear discriminant analysis were explored to obtain efficient classification of the Raman signals obtained from the four strains of <em>E.coli</em>. It was observed that multivariate analysis was able to classify the bacteria at strain level. Linear discrimination analysis using PC scores (PC-LDA) was found to give very good result with as high as 100% accuracy. This hybrid technique (Raman spectroscopy &amp; multivariate analysis) has tremendous potential to be developed as a tool for bacterial identification.<span class="Apple-converted-space"> </span></p>

Prevalence and significance of antiphospholipid antibodies in selected at-risk obstetrics cases: a comparative prospective study

In a prospective comparative study we screened 112 women with a past history either of pre-eclampsia, eclampsia, recurrent abortion, IUGR, IUFD or abruptio placentae, with no apparent aetiology and a demographically matched cohort of 106 women having a past history of uncomplicated pregnancy outcome for the presence of antiphospholipid antibodies (aPL) and their significance. In the former group, the prevalence of aPL ranged from 10-46.87% compared with 8.49% in the later group. In women with the presence of aPL, the incidence of pre-eclampsia, early onset pre-eclampsia and abruptio placentae were 25%, 14.58% and 18.75%, respectively. In the same group, the abortion rate was 25% and live-birth rate was 64.58% with IUFD rate of 10.42%. Fetal morbidity rates were also higher in the mothers with aPL positivity, the incidence of IUGR was 27.08% and oligohydramnios was 33.33% in them. All these complications were statistically significant when compared with those of aPL negative mothers.

Choroidal melanoma of left eye with very early liver metastasis

Uveal melanoma is a cancer (melanoma) of the eye involving the iris, ciliary body, or choroid (collectively referred to as the uvea). The liver is a frequent site for metastasis in patients with uveal melanoma. The interval between the diagnosis of the uveal melanoma and the diagnosis of the metastatic lesion can vary. Despite therapy, the median survival of those with liver metastasis is 5-7 months. We report here a rare case of choroidal melanoma in a 45-year-old male smoker presented with liver metastasis within just 8 months after completion of initial treatments consists of enucleation of eye and 3 Dimensional conformal radiation therapy (3D-CRT). The metastasis is an incidental finding on imaging after having some vague symptoms. This type of very early metastasis after completing initial treatment is very rare and proves the aggressiveness of the disease.

Arsenate resistance as a possible marker in the differentiation of environmental and clinical isolates of Vibrio parahaemolyticus

Strains of Vibrio parahaemolyticus were isolated from clinical, marine and freshwater fish of Calcutta, West Bengal, India. Drug and metal resistance characteristics were compared for differentiation of clinical and environmental strains. Eighteen out of the twenty environmental isolates were resistant to arsenate, unlike the clinical isolates which were all susceptible. All the thirty-five isolates of V. parahaemolyticus were resistant to ampicillin and streptomycin.

Protoporphyrin IX potentiates horseradish peroxidase-catalyzed oxidation of NADH:Involvement of enzyme-porphyrin interaction

Protoporphyrin IX potentiates horseradish peroxidase-catalyzed hydrogen peroxide-mediated NADH oxidation, but the porphyrin cannot change the enzyme-catalyzed o-dianisidine oxidation. Spectrofluorimetric studies reveal that an interaction occurs between horseradish peroxidase and protoporphyrin IX. The interaction is predominantly hydrophobic and entropy-driven endothermic process. This interaction may influence the potentiation effect of the protoporphyrin IX on horseradish peroxidase-catalyzed NADH oxidation because the latter has a positive correlation with the extent of binding of the protein with the porphyrin.

Design and delivery of the Refractive Errors Among Children (REACH) school-based eye health programme in India

CLINICAL RELEVANCE

Optimisation of vision screening programmes can result the detection of refractive anomalies in a high proportion of school children.

BACKGROUND

The Refractive Errors Among Children (REACH) programme aims to optimise outcomes of school-based vision screening in India by collaborating with hospitals and monitoring eye care throughout school attendance.

METHODS

REACH delivers school vision screening using pocket vision screeners (cards presenting rows of seven 0.2 logMAR Sloan letters at a 3 m viewing distance) in five states across India. Children who fail screening are referred for detailed evaluation including refraction, those requiring cycloplegic refraction are referred to partner hospitals. Spectacles are dispensed as needed and compliance is assessed. All data are recorded electronically.

RESULTS

Out of 2,240,805 children aged 5 to 18 (mean 11.5; SD ±3.3) years, 2,024,053 have undergone REACH screening in 10,309 schools predominantly in rural locations (78.7%) and government-funded (76%). Of those screened, 174,706 (8.6%) underwent detailed evaluation. A higher proportion of children in private or urban schools (11.8% and 10.4% respectively) were referred for detailed evaluation than those in government-funded or rural schools (5.9% and 7.2%, respectively; p < 0.001). The proportion referred for detailed evaluation differed by state (p < 0.001), from 4.0% in West Bengal to 14.4% in Kerala.

CONCLUSION

The REACH programme screened a high proportion of school children, providing further care and follow-up to optimise visual outcomes.

Effects of Habitat and Fruit Scent on the Interactions between Short-tailed Fruit Bats and Piper Plants

Piper is a mega-diverse genus of pioneer plants that contributes to the maintenance and regeneration of tropical forests. In the Neotropics, Carollia bats use olfaction to forage for Piper fruit and are a main disperser of Piper seeds via consumption and subsequent defecation during flight. In return, Piper fruits provide essential nutrients for Carollia year-round. There is evidence that the types and diversity of Piper frugivores are influenced by the primary habitat type of different Piper species (forest and gap), with forest Piper depending more on bats for seed dispersal; however, this pattern has not been tested broadly. We aimed to characterize and compare the interactions between Carollia and Piper across forested and gap habitats, and further investigate whether differences in fruit traits relevant to bat foraging (i.e., scent) could underlie differences in Carollia-Piper interactions. We collected nightly acoustic ultrasonic recordings and 24 h camera trap data in La Selva, Costa Rica across 12 species of Piper (six forest, six gap) and integrated this information with data on Carollia diet and Piper fruit scent. Merging biomonitoring modalities allowed us to characterize ecological interactions in a hierarchical manner: from general activity and presence of bats, to visitations and inspections of plants, to acquisition and consumption of fruits. We found significant differences in Carollia-Piper interactions between forested and gap habitats; however, the type of biomonitoring modality (camera trap, acoustics, diet) influenced our ability to detect these differences. Forest Piper were exclusively visited by bats, whereas gap Piper had a more diverse suite of frugivores; the annual diet of Carollia, however, is dominated by gap Piper since these plants produce fruit year-round. We found evidence that fruit scent composition significantly differs between forest and gap Piper, which highlights the possibility that bats could be using chemical cues to differentially forage for gap vs. forest Piper. By integrating studies of Piper fruit scent, plant visitation patterns, and Carollia diet composition, we paint a clearer picture of the ecological interactions between Piper and Carollia, and plant-animal mutualisms more generally.

Cyclometalated Iridium(III) Complex with Substituted Benzimidazole: pH Directed Organelle-Specific Localization Within Lysosome

We report the synthesis and pH dependent emission spectral behaviour of four emissive iridium(III) complexes (Ir1-Ir4) with two isomeric pairs of bis-trifluoromethyl appended benzimidazole ligands. The imidazolyl hydrogen(N-H) has been replaced by phenyl groups (N-Ph) in two ligands to understand the impact of hydrogen bonding on the photophysical properties of the complexes and it indeed plays interesting role in the charge-transfer dynamics. The pH dependent electronic spectral change is observed for two of the complexes. The enhancement of emission intensity is observed at different wavelength for pH<7 and pH>7 for Ir1 and Ir3. The emission sensing of biogenic amines with pka values ranging from 5.80-9.74 is reported along with cellular imaging. The complex Ir1 specifically localizes within lysosome (pH=4.5-5) and thus image this organelle with great precision. The detail electronic spectra and electrochemical behaviour were reported here along with TDDFT results.

Comparative studies on the interaction of protoporphyrin with hemoglobin and myoglobin

The binding parameters of protoporphyrin IX (PPIX) with hemoglobin (Hb) were studied spectrofluorimetrically and the results were compared with those of PPIX interacting with myoglobin (Mb). Two concentration ranges of PPIX (0.3 microM-1.5 microM and 1.5 microM-3.0 microM) were used. For both hemoglobin and myoglobin, the binding affinity constant (K) decreased while the number of binding sites (p) increased as the concentration range of PPIX increased. The interactions occurred in non-cooperative mode. Over a particular PPIX range, the interaction of PPIX with hemoglobin decreased significantly with increasing NaCl molarity indicating a trend in electrostatic interaction, whereas PPIX binding with myoglobin did not change significantly indicating mostly non-electrostatic mode of interaction. Total bound charge (z psi) decreased significantly with increased PPIX concentration range in case of hemoglobin-PPIX interaction, but remained almost same in case of myoglobin-PPIX interactions. Thermodynamic analysis revealed that binding of PPIX to hemoglobin was mostly electrostatic at lower concentration range of PPIX but became less electrostatic at higher concentration range and myoglobin-PPIX interaction, predominantly hydrophobic in nature, became more hydrophobic with increased range of PPIX concentration. The difference in binding modality between PPIX-Hb and PPIX-Mb has been discussed in relation to the state of aggregation of porphyrin as well as the subunit interaction property present and absent in hemoglobin and myoglobin, respectively.