PREVALENCE OF ENDEMIC GOITRE IN SCHOOL CHILDREN: SHIRUR (DIST. PUNE,MAHARASHTRA)

A survey for estimation of goitre in school children in the Rural Health Training Centre, Shirur area was undertaken. A total of 4664 students from 17 schools were surveyed. The goitre prevalence was found to be 59.8% with visible goitre rate of 6.2% in pre- and peri-adolescent (10–19 years) age group. Thus a highly endemic goitre focus was located in Shirur, area in Pune District (Maharashtra). This area is located on the eastern tail-end slopes of Sahyadri Hills in Balaghat ranges, situated at an altitude of 533 metres. The area is generally drought prone and receives scanty rain, with poor agricultural practices. Environmental deficiency of iodine was found to be the main cause for this high prevalence of goitre.KEY WORDS: Goitre endemic, Iodine     

Modulation of frustration in folding by sequence permutation

Folding of globular proteins can be envisioned as the contraction of a random coil unfolded state toward the native state on an energy surface rough with local minima trapping frustrated species. These substructures impede productive folding and can serve as nucleation sites for aggregation reactions. However, little is known about the relationship between frustration and its underlying sequence determinants. Chemotaxis response regulator Y (CheY), a 129-amino acid bacterial protein, has been shown previously to populate an off-pathway kinetic trap in the microsecond time range. The frustration has been ascribed to premature docking of the N- and C-terminal subdomains or, alternatively, to the formation of an unproductive local-in-sequence cluster of branched aliphatic side chains, isoleucine, leucine, and valine (ILV). The roles of the subdomains and ILV clusters in frustration were tested by altering the sequence connectivity using circular permutations. Surprisingly, the stability and buried surface area of the intermediate could be increased or decreased depending on the location of the termini. Comparison with the results of small-angle X-ray–scattering experiments and simulations points to the accelerated formation of a more compact, on-pathway species for the more stable intermediate. The effect of chain connectivity in modulating the structures and stabilities of the early kinetic traps in CheY is better understood in terms of the ILV cluster model. However, the subdomain model captures the requirement for an intact N-terminal domain to access the native conformation. Chain entropy and aliphatic-rich sequences play crucial roles in biasing the early events leading to frustration in the folding of CheY.Highly denatured states of globular proteins resemble statistical random coils when examined with low-resolution techniques such as X-ray scattering (1) and hydrodynamic analyses (2). However, a higher-resolution view provided by experimental models (3–6) and simulations (7) shows that the conformational ensemble is biased toward low-contact-order (CO) structures, e.g., α-helices, β-turns, and β-hairpins, which form and melt in less than a few microseconds. During folding, these nascent structures presumably coalesce into higher-order assemblies of ever-increasing free energy until reaching the transition-state ensemble (TSE) that leads to the native conformation. From another perspective, this assembly process mediates a global collapse of the chain in an unfavorable solvent (8). Landscape theory (9) posits that, in the simplest scenario, native-like substructures appear and lead without pause to the TSE and the native conformation in an apparent two-state fashion. However, simulations have found that topological frustration, e.g., the premature formation of a substructure that impedes access to the productive TSE, can lead to the accumulation of intermediates (I) that must unfold to some extent to traverse the folding reaction coordinate successfully (8, 10, 11). Experimental and computational studies on the folding of the α-subunit of Trp synthase (12, 13), the chemotaxis response regulator Y (CheY) (10, 14), a pair of apo-flavodoxins (8, 15, 16), and tandem titan domains (17) revealed frustration in the form of off-pathway intermediates (I_OFF). Thus, as-yet unexplored aspects of sequence and structure can add complexity to folding reactions.The observed inverse relationship between CO and folding rate constant (18) implies that elements of secondary structure that are near in sequence and near in space will associate preferentially over those that are distant in sequence. However, if such low-CO substructures are not involved in the productive TSE, they could serve as sources of frustration. A case in point is CheY, a member of the very common flavodoxin-fold family with its classic α/β/α sandwich architecture. The (β/α)5 motif displays the α1 and α5 helices on one face of the parallel β-sheet and the α2, α3, and α4 helices on the opposing face (Fig. 1 A and B). The proposed kinetic folding mechanism (Fig. 1C) (14) involves two parallel folding channels defined by the cis and trans isomers of the prolyl peptide bond between K109/P110. The unfolded proteins (U) in both the major trans (U_t) (90%) and minor cis (U_c) (10%) channels sample an off-pathway submillisecond intermediate (I_BP), I_BPt and I_BPc, respectively, before the rate-limiting isomerization reaction in the I_BPt→I_BPc step. I_BPc unfolds to the U_c state before accessing the productive TSE leading to the native conformation (N) in the U_c →N_c step. Further complicating the mechanism is an on-pathway intermediate, I_ON, between U_c and N_c that has been observed by equilibrium NMR measurements (19) and in Gō-model simulations (10) but not by circular dichroism (CD) or flow fluorescence (FL) experiments.Open in a separate windowFig. 1.(A) Topology diagram of CheY. The N-terminal folding subdomain is highlighted in yellow, and the C-terminal folding subdomain is highlighted in blue. The effects of each permutation on the continuity of cluster 1 (blue), and cluster 2 (red) are shown. (B) Clusters of ILV residues are superimposed on the crystal structure of CheY (Protein Data Bank ID code: 3CHY). Cluster 1 (blue) has a lower CO and resides on the α2/α3/α4 side of the central β-sheet. The larger cluster 2 (red) contains high-CO contacts and resides on the α1/α5 side of the β-sheet. (C) The folding mechanism of WT CheY. The major pathway is highlighted in red. The U_c →N_c step, involving the on-pathway intermediate, is designated by the triple dots.Mutational analysis (20, 21) has revealed a nucleation-condensation folding mechanism for CheY in which the N-terminal subdomain [residues 1–70, (βα)1–2β3] serves as the nucleus for the subsequent condensation of the C-terminal subdomain [residues 70–129, α3(βα)4–5] (Fig. 1A). However, native-centric simulations identified contacts between the N- and C-terminal subdomains, centered around (βα)3–4, early in folding that are incompatible with access to the productive TSE and that lead to frustration in the folding mechanism (10). Another perspective is provided by the branched chain aliphatic side chains (BASiC) hypothesis, which supposes that large clusters of isoleucine, leucine, and valine (ILV) side chains serve as cores of stability in folding intermediates (11, 14). Both these clusters have been shown to have a high contact density (22). CheY has two ILV clusters, each serving to fuse the surface helices to each other and to the central β-sheet (Fig. 1B). The smaller cluster (cluster 1) contains 10 side chains and primarily links α2(βα)3β4 on one face of the β-sheet; the larger cluster (cluster 2) contains 15 side chains and links the β-strands to α1 and α5. The sequence spanned by the smaller cluster agrees closely with the (βα)3–4 segment identified as the source of frustration in the simulations and, importantly, involves only low-CO contacts. If cluster 1 were to form early and, by sequestering β3, impede the development of the productive TSE in the N-terminal subdomain, (βα)1–2β3, the BASiC hypothesis would provide an alternative explanation for frustration in the folding of CheY.Permutations in the sequence of CheY provide a means to compare the subdomain model and the ILV cluster model as explanations for the frustration in folding detected by simulations and experiments. By fusing the natural N and C termini with a short linker peptide (Gly-Ala-Gly) and inserting new termini in the loops after β2, β3, and β4, it is possible to cleave within the N-terminal subdomain (Cpβ2), between the subdomains (Cpβ3), and within the C-terminal subdomain (Cpβ4). Related to the ILV clusters, Cpβ2 cleaves cluster 1 and leaves cluster 2 largely intact, Cpβ3 cleaves both clusters, and Cpβ4 cleaves only cluster 2 (Fig. 1A). Our simulations and experiments on these permutants show that aspects of both models describe the relationships between sequence, structure, and frustration in the folding of CheY. The results also show that frustration can be modulated by sequence permutations that can bias the initial stages of folding toward the productive TSE and away from kinetic traps.     

Orthotopic liver transplantation in a patient with carbamyl phosphate synthetase deficiency and cystic fibrosis

A 15-year-old female with carbamyl phosphate synthetase deficiency, cystic fibrosis, and cystic fibrosis-related diabetes underwent orthotopic cadaveric liver transplantation. Metabolic control was maintained during the procedure with nutritional support and the use of intravenous sodium phenylacetate and benzoate. Her postoperative course was complicated by seizures and a transient decline in her pulmonary function tests, which returned to preoperative levels within one year of the transplant. Now, four years post-transplant, her quality of life has dramatically improved. There are only four Canadian centres with paediatric liver transplantation programs. However, expert medical care for adults with inborn error of metabolism is even more limited, suggesting that access to adult medical care is one of the many factors to be considered when liver transplantation is contemplated for patients with metabolically unstable conditions.     

Bioinformatics analysis of diabetic retinopathy using functional protein sequences

Diabetic retinopathy is the leading cause of blindness among patients with diabetes mellitus. We evaluated the role of several proteins that are likely to be involved in diabetic retinopathy by employing multiple sequence alignment using ClustalW tool and constructed a phylogram tree using functional protein sequences extracted from NCBI. Phylogram was constructed using Neighbor-Joining Algorithm in bioinformatics approach. It was observed that aldose reductase and nitric oxide synthase are closely associated with diabetic retinopathy. It is likely that vascular endothelial growth factor, pro-inflammatory cytokines, advanced glycation end products, and adhesion molecules that also play a role in diabetic retinopathy may do so by modulating the activities of aldose reductase and nitric oxide synthase. These results imply that methods designed to normalize aldose reductase and nitric oxide synthase activities could be of significant benefit in the prevention and treatment of diabetic retinopathy.     

Molecular characterization of nontypeable group B streptococcus

Traditionally, the capsular polysaccharide (CPS) antigen has been used to distinguish between the nine known serotypes of group B streptococcus (GBS) by classical antibody-antigen reactions. In this study, we used PCR for all CPSs and selected protein antigens, multilocus sequencing typing (MLST), and pulsed-field gel electrophoresis (PFGE) to molecularly characterize 92 clinical isolates identified as nontypeable (NT) by CPS-specific antibody-antigen reactivity. The PCR and MLST were performed on blinded, randomly numbered isolates. All isolates contained the cfb gene coding for CAMP factor. While most (56.5%) contained a single CPS-specific gene, 40 isolates contained either two or three CPS-specific genes. Type V CPS-specific gene was present in 66% of the isolates, and all serotypes except types IV, VII, and VIII were represented. Most (44.5%) of the isolates contained a single protein antigen gene (bca, bac, rib, alp1, or alp3), and the remaining isolates had multiple protein antigen genes. Of the 61 isolates that had the V CPS-specific gene, 48 (78.6%) had the alp3 gene. PFGE analysis classified the isolates into 21 profile groups, while MLST analysis divided the isolates into 16 sequence types. Forty-two (69%) of 61 isolates with the V CPS-specific gene were in PFGE profile group 4; 41 of these 42 were sequence type 1 by MLST. These data shed new light on the antigenic complexity of NT GBS isolates, information that can be valuable in the formulation of an effective GBS vaccine.     

Bilateral mandibular metastases in medulloblastoma

Medulloblastoma is the most common malignant brain tumor of childhood, with a propensity for neuraxial spread via the cerebrospinal fluid. However, systemic metastases can occur in a small minority of patients. Very rarely such metastases can involve the mandible and present with intra-oral swelling. One such occurrence in a patient with medulloblastoma in the setting of disseminated disease is reported with a review of the relevant literature. The treatment options for patients with extra-neuraxial metastases are limited and their prognosis continues to remain poor.     

A novel protein tyrosine phosphatase gene is mutated in progressive myoclonus epilepsy of the Lafora type (EPM2)

Progressive myoclonus epilepsy of the Lafora type or Lafora disease (EPM2; McKusick no. 254780) is an autosomal recessive disorder characterized by epilepsy, myoclonus, progressive neurological deterioration and glycogen-like intracellular inclusion bodies (Lafora bodies). A gene for EPM2 previously has been mapped to chromosome 6q23- q25 using linkage analysis and homozygosity mapping. Here we report the positional cloning of the 6q EPM2 gene. A microdeletion within the EPM2 critical region, present inhomozygosis in an affected individual, was found to disrupt a novel gene encoding a putative protein tyrosine phosphatase (PTPase). The gene, denoted EPM2, presents alternative splicing in the 5' and 3' end regions. Mutational analysis revealed that EPM2 patients are homozygous for loss-of-function mutations in EPM2. These findings suggest that Lafora disease results from the mutational inactivation of a PTPase activity that may be important in the control of glycogen metabolism.      

Epstein-Barr virus association in classical Hodgkin''s disease provides survival advantage to patients and correlates with higher expression of proliferation markers in Reed-Sternberg cells.

Background:Most Epstein–Barr virus (EBV) associatedlymphoproliferative disorders have high proliferation indices. However,classical Hodgkin's disease (cHD) is heterogeneous, with respect toproliferation index of the Reed–Sternberg cell (RS cell), and EBVassociation. Hence, we investigated whether cHD with and withoutEBV-association differ with respect to the proliferation index of the RScells. Further we investigated whether this would have a bearing on patientssurvival. Patients and methods: We investigated 110 cases of cHD for: a) EBVassociation by immunohistochemical demonstration of EBV-latent membraneprotein-1 and EBV encoded nuclear RNA 1 by mRNA in situhybridisation; b) Proliferating cell nuclear antigen (PCNA) expressionin the RS cells. Results:EBV association was noted in 86 of 110 cases(78%). Higher PCNA expression (P = 0.004) and younger age(P = 0.001) correlated independently with EBV association. The 10year relapse free survival (RFS) of EBV+ and EBV– patients were60% and 44%, respectively (P = 0.03). The 10 yearoverall survival (OS) of EBV+ and EBV– patients were 85% and64%, respectively (P = 0.03). EBV association maintained itssignificant impact on RFS and OS within Cox proportional hazard model. Conclusions:Our study suggests that EBV is likely to confer ahigher PCNA expression and also contribute towards maintaining the RS cellsof cHD in cell cycle. Hence, RS cells in EBV associated cHD would be moreresponsive to chemotherapy and radiotherapy associated DNA damage. Thus,EBV-association provides survival advantage to cHD patients treated withstandard chemotherapy and radiotherapy protocols.