Functional regulation of an intrinsically disordered protein via a conformationally excited state

A longstanding goal in the field of intrinsically disordered proteins (IDPs) is to characterize their structural heterogeneity and pinpoint the role of this heterogeneity in IDP function. Here, we use multinuclear chemical exchange saturation (CEST) nuclear magnetic resonance to determine the structure of a thermally accessible globally folded excited state in equilibrium with the intrinsically disordered native ensemble of a bacterial transcriptional regulator CytR. We further provide evidence from double resonance CEST experiments that the excited state, which structurally resembles the DNA-bound form of cytidine repressor (CytR), recognizes DNA by means of a "folding-before-binding" conformational selection pathway. The disorder-to-order regulatory switch in DNA recognition by natively disordered CytR therefore operates through a dynamical variant of the lock-and-key mechanism where the structurally complementary conformation is transiently accessed via thermal fluctuations.

Functional Outcome of Subtrochanteric Femoral Fracture Fixation by Intramedullary Interlocking Surgical Implant Generation Network Nail

Subtrochanteric femoral fractures are one of the common fractures encountered in today's Orthopaedic practice. High stress leads implant failure and produce varus collapse. From the perspective of biomechanics, intramedullary fixation has unique advantage which can better distribute stress and acting load-sharing implants. Biomechanically proximal wide canal and short segment provide less optimal fixation by conventional intramedullary nails. Intramedullary nail by Surgical Implant Generation Network (SIGN) has proximal interlocking that gain purchase through femoral neck and provide improved stability for proximal part. The aim of this study was to evaluate the functional outcome of subtrochanteric fractures fixation by intramedullary interlocking SIGN nail. This prospective study was conducted from July 2016 to June 2018 at National Institute of Traumatology and Orthopaedic Rehabilitation (NITOR) through non randomized purposive sampling. Total 31 patients, aged above 18 years irrespective of sex with closed subtrochanteric fractures were included. Patients with pathological fracture, multiple injuries were excluded from the study. The mean age of the patients was 42.61±19.59 years with range 18-80 years. Most common fractures were Seinsheimer type III (51.6%) and average follows up 42.39 weeks (24-48 weeks). Union rate 93.55% with delayed union 6.45% and no nonunion. Functionally most of patient started early partial (77.42%) and full (64.52%) weight bearing with 61.29% have full knee ROM and 83.9% without limb shortening. Maximum patients regained walking (83.87%) and squatting (90.32%) and return to preinjury state (80.65%) of activities. Evaluation of outcome by Modified Harris Hip Score showed excellent (70.97%), good (22.58%), fair (3.23%) and poor (3.23%) thus satisfactory outcome were 93.55%. This study concludes that intramedullary interlocking SIGN nail is a safe and reliable implant for the treatment of subtrochanteric fractures with excellent functional outcome.

Result of Subtrochanteric Femoral Fracture Fixation by Intramedullary Interlocking Surgical Implant Generation Network (SIGN) Nail

Treatment of sub-trochanteric femoral fractures is a challenge to orthopaedic surgeons. High incidence of fixation failure and nonunion is due to thick cortical bone deserves special consideration of surgical treatment. Intramedullary nail by Surgical Implant Generation Network (SIGN) shows promising results in comparison to conventional fixation method because of its better strength, accuracy and surprisingly better results in infection and non-union. The aim of this study was to assess the rate and time taken for union of fractures by SIGN nail and determine peri-operative parameters. This prospective study was conducted from July 2016 to June 2018 at National Institute of Traumatology and Orthopaedic rehabilitation (NITOR) through non randomized purposive sampling. Total 31 patients, aged above 18 years irrespective of sex with closed subtrochanteric fractures were included. Patients with pathological fracture, multiple injuries were excluded from the study. Union status evaluated by Radiographic Union Score for Tibial (RUST) fracture where antero-posterior and lateral radiographs (X-ray) based assessment of healing of the four cortices done. The individual cortical scores were added to give a total score 4 being the minimum indicating fracture is definitely not healed and 12 being the maximum score indicating that the fracture is definitely healed. The mean age of the patients was 42.61±19.59 years with range 18-80 years. Majority of patients were male (68%) and most of injury (68%) due to road traffic accident with common fracture were Seinsheimer type III (51.6%). Average hospital stay period was 16.39 days and average follows up 42.39 weeks (24-48 weeks). Time taken for union was 14.16 weeks (11-28 weeks). According to RUST scores fracture union rate 93.55% with delayed union 6.45% and no nonunion. There was one patient with superficial wound infection, one unaccepted shortening and with no implant failure. This study concludes that intramedullary interlocking SIGN nail is a safe and reliable implant for the treatment of subtrochanteric femoral fractures.

Prospective Study of Deterioration of Quality-of-Life among Elderly Women with Untreated Fracture of Neck of Femur in Rural Areas of Mymensingh, Bangladesh

Elderly women are very much prone to develop fracture at neck of femur sustained by even minute trauma. Most of the cases are due to fall. Osteoporosis gives rise to this vulnerable condition. In developing countries like Bangladesh the women of rural areas are the prime victims mostly due to illiteracy. To assess the quality-of-life (QOL) of elderly women (>60 years) with untreated hip fractures in a rural areas in Mymensingh, Bangladesh is the objective of this study. This prospective study was done from January 2019 to December 2019 in Orthopaedics and Traumatology Department of Mymensingh Medical Hospital, Mymensingh, Bangladesh. Twenty-five elderly women with untreated fracture neck of femur were enlisted in this study. EuroQol (EQ-5D) was applied to assess the Quality of life of subjects before and after the situation. Twenty-five elderly women of healed operated neck of femur were included as comparison group, matched for age, economic condition and educational status among neighborhood people. So, sample size was fifty. Wilcoxon signed rank test and Mann-Whitney U test were applied to compare EQ-5D mean scores. Participants with hip fracture, 60% (15/25), 68% (17/25), 68% (17/25), 60% (15/25) and 92% (23/25) reported severe problems with mobility, pain, usual activity, self-care and anxiety respectively. The EQ-5D mean score among the elderly with fracture neck of femur was 0.198 (SD 0.14). It was low when compared with the same subjects before the occurrence of the event (Z-6.522, p<0.001) and as compared with the comparison group (Z-7.92 p<0.001). QOL scores assessed using EQ-5D index scores was poor among elderly women with untreated fracture neck of femur as compared with the healed operated comparison group. Vast majority of study participants in this study were reported severe problems like mobility, pain, usual activity and self-care and anxiety.

SARS-CoV-2 prevalence and immunity: a hospital-based study from Malawi

Background

COVID-19 transmission and disease dynamics in sub-Saharan Africa are not well understood. Our study aims to provide insight into COVID-19 epidemiology in Malawi by estimating SARS-CoV-2 prevalence and immunity after SARS-CoV-2 infection in a hospital-based setting.

Methods

We conducted a hospital-based, convenience sampling, cross-sectional survey for SARS-CoV-2 in Lilongwe, Malawi. Participants answered a questionnaire and were tested for SARS-CoV-2 by enzyme-linked immunosorbent assay and real-time reverse-transcription polymerase chain reaction (RT-PCR). A surrogate virus neutralization test (sVNT) was performed in seropositive samples to estimate immunity. Poisson regression was used to assess SARS-CoV-2 point prevalence association with demographic and behavioral variables.

Findings

The study included 930 participants. We found a combined point prevalence of 10.1%. Separately analyzed, RT-PCR positivity was 2.0%, and seropositivity was 9.3%. Of tested seropositive samples, 90.1% were sVNT positive. We found a high rate (45.7%) of asymptomatic SARS-CoV-2 infection. SARS-CoV-2 point prevalence was significantly associated with being a healthcare worker.

Interpretation

Our study suggests that official data underestimate COVID-19 transmission. Using sVNTs to estimate immunity in Malawi is feasible and revealed considerable post-infection immunity in our cohort. Subclinical infection and transmission are probably a game-changer in surveillance, mitigation and vaccination strategies.

Metamorphic proteins: the Janus proteins of structural biology

The structural paradigm that the sequence of a protein encodes for a unique three-dimensional native fold does not acknowledge the intrinsic plasticity encapsulated in conformational free energy landscapes. Metamorphic proteins are a recently discovered class of biomolecules that illustrate this plasticity by folding into at least two distinct native state structures of comparable stability in the absence of ligands or cofactors to facilitate fold-switching. The expanding list of metamorphic proteins clearly shows that these proteins are not mere aberrations in protein evolution, but may have actually been a consequence of distinctive patterns in selection pressure such as those found in virus–host co-evolution. In this review, we describe the structure–function relationships observed in well-studied metamorphic protein systems, with specific focus on how functional residues are sequestered or exposed in the two folds of the protein. We also discuss the implications of metamorphosis for protein evolution and the efforts that are underway to predict metamorphic systems from sequence properties alone.

Clinical Outcome in Intra Articular Distal Humerus Fractures in Adults Treated with Different Hardware in a Tertiary Level Hospital of Bangladesh

In adults, distal humerus fractures are infrequent and frequently intra-articular. Customarily encompass both medial and lateral columns. Operative management gives constructive outcomes. The aim of this study was to evaluate clinical outcome in intra articular distal humerus fractures in adults treated by different hardware. This prospective study consists of 20 purposively selected patients with intra articular distal humerus fractures treated by surgical intervention with different hardware who were admitted to Mymensingh Medical College and Hospital, Bangladesh in between November 2016 to October 2018. Surgical approaches were standard dorsal with or without olecranon osteotomy. The mean age of the patients was 32.3 years, range between 18-55 years. The maximum patients i.e. 85% were between 18-45 years. Seventy percent (70%) of the cases admitted were due to Road traffic accident (RTA). Most of the patients were males 14(70%) with right upper limb was involved in 13(65%) cases. Mean Mayo Elbow Performance Score was 81.5 post-operatively. According to Mayo Elbow Performance (MEP) score clinical outcome was excellent in 20%, good in 50%, fair in 25% and poor in 10% of patients. Distal humerus fractures are censorious in nature. Proper anatomical articular reconstruction and stable fixation by surgical intervention helps in fruitful results.

Giant Cell Tumour of the Talus: A Rare Case Report

Giant-cell tumor constitutes 4-20% of all primary bone tumors in south East Asian population. They are benign locally aggressive bone tumour first described by cooper in 1818. These tumors occur predominantly in meta-epiphyseal region. Most often they are located around the knee joint. Although most of the tumors are diagnosed on plain radiograph alone, varying CT and MRI presentations of these tumors are essential to narrow down the differentials has an extended pre operative assessment.

Comparative Study of Stabilization of Humerus Supracondylar Fracture in Children by Percutaneous Pinning From Lateral Side and Both Sides

The aim of this prospective experimental study was to analyze the radiological and clinical results of the supra condylar fracture of Humerus in children and conducted the functional outcome of closed reduction and internal fixation by percutaneous Kirschner-wire from lateral side and crossed technique in the National Institute of Traumatology and Orthopaedic Rehabilitation (NITOR), Sher-E-Bangla Nagor, Dhaka, Bangladesh from July 2011 to June 2013. Patients diagnosed as closed Supracondylar fracture of Humerus in children due to trauma were the study population. Total 30 patients aged 2 to 12 years irrespective of sex were included in the study and were divided in 2 groups. Information obtained included age, sex, type of fracture, management, outcomes and complications. The mean age was 7.80±2.08 and 5.93±2.31 years for Group I and Group II patients. Age range was 2-12 years. Males were predominant 11(73.3%) Group I and Group II. Fractures were primarily caused by fall from tree and left side predominant. In Group I the time elapsed between injury and surgery was minimum 2 hours and maximum 24 hours with mean±SD was 9.20±7.20, while in Group II minimum and maximum of 3 and 48 hours respectively with mean±SD was 9.60±11.01. Minimum and maximum post operative hospital stays were 1 and 2 days in Group I and Group II. Follow-up were carried out after 1, 3, 6 and 12 weeks of operation. Loss of post operative range of motion of elbow and loss of carrying angle was not significant (p>0.05). Functional outcome was analyzed by Flynn's grading. In this study there were 3(20%) cases with excellent, 10(66.67%) were good and 2(13.33%) were fair functional outcomes in Group I. In Group II excellent, good and fair functional outcome were 3(20%), 9(60%) and 3(20%) respectively. After chi-square test there was no significant difference between two groups.

The roles of homologous recombination and the immune system in the genomic evolution of cancer

A variety of factors, whether extracellular (mutagens/carcinogens and viruses in the environment, chronic inflammation and radiation associated with the environment and/or electronic devices/machines) and/or intracellular (oxidative metabolites of food, oxidative stress due to inflammation, acid production, replication stress, DNA replication/repair errors, and certain hormones, cytokines, growth factors), pose a constant threat to the genomic integrity of a living cell. However, in the normal cellular environment multiple biological pathways including DNA repair, cell cycle, apoptosis and the immune system work in a precise, regulated (tightly controlled), timely and concerted manner to ensure genomic integrity, stability and proper functioning of a cell. If damage to DNA takes place, it is efficiently and accurately repaired by the DNA repair systems. Homologous recombination (HR) which utilizes either a homologous chromosome (in G1 phase) or a sister chromatid (in G2) as a template to repair the damage, is known to be the most precise repair system. HR in G2 which utilizes a sister chromatid as a template is also called an error free repair system. If DNA damage in a cell is so extensive that it overwhelms the repair system/s, the cell is eliminated by apoptosis. Thus, multiple pathways ensure that genome of a cell is intact and stable. However, constant exposure to DNA damage and/or dysregulation of DNA repair mechanism/s poses a risk of mutation and cancer. Oncogenesis, which seems to be a multistep process, is associated with acquisition of a number of genomic changes that enable a normal cell to progress from benign to malignant transformation. Transformed/cancer cells are recognized and killed by the immune system. However, the ongoing acquisition of new genomic changes enables cancer cells to survive/escape immune attack, evolve into a more aggressive phenotype, and eventually develop resistance to therapy. Although DNA repair (especially the HR) and the immune system play unique roles in preserving genomic integrity of a cell, they can also contribute to DNA damage, genomic instability and oncogenesis. The purpose of this article is to highlight the roles of DNA repair (especially HR) and the immune system in genomic evolution, with special focus on gastrointestinal cancer.

Correlation of Foot Height with Stature in 5-10 Years Aged Bangladeshi Children

This cross sectional, descriptive and analytic type study was conducted among 5-10 years aged Bangladeshi children at different areas of Mymensingh district (Fulpur, Muktagacha, Fulbaria, Trisal and Haluaghat) on 109 Bangladeshi children (70 male and 39 female) from January 2016 to December 2016. Sample collection was done by nonrandom purposive sampling technique. Any kind of foot deformity resulting either from congenital or physical injury were excluded to construct standard measurement. The present anthropometric study was designed to construct data of 5 to 10 years aged Bangladeshi children regarding foot height, to measure correlation of stature with foot height and an attempt has been made out to grow interest among the researchers for future study and also to compare the data with the data of the people of other races. Stature of the subject was measured with the stadiometer and foot height was measured using flexible measuring tape. The children were asked to stand with weight distributed equally on both feet. The legs were perpendicular to the feet. The mean foot height of both sides of 5, 6, 7, 8, 9 and 10 years aged male were 5.90±0.76cm, 5.76±0.64cm, 6.80±0.35cm, 6.86±0.35cm, 7.24±0.46cm and 7.28±0.66cm respectively and those of female were 5.48±0.67cm, 6.25±0.28cm, 6.19±0.58cm, 6.42±0.34cm, 6.30±0.49cm and 6.30±0.39cm respectively. Correlation between stature and foot height was made. Foot height showed non-significant positive correlation with stature in 5 years old male, 6 years old male, 7 years old male and female, 8 years old male, 9 years old male and female and 10 years old male and female. In case of 5 years old female, it showed significant positive correlation with stature.

Laparoscopic surgery for acute neonatal appendicitis

We present the first two cases of acute neonatal appendicitis operated on through the laparoscopic approach. Acute neonatal appendicitis is uncommon and rarely considered by clinicians when assessing the neonatal acute abdomen. Our two cases demonstrate the potential value of diagnostic laparoscopy in the acute neonatal abdomen that poses a diagnostic dilemma. Furthermore, technical modifications of well-established laparoscopic techniques in the older child enable its use in neonates as a therapeutic tool.

Amniotic fluid embolism

The disastrous entry of amniotic fluid into the maternal circulation leads to dramatic sequelae of clinical events, characteristically referred to as Amniotic fluid embolism (AFE). The underlying mechanism for AFE is still poorly understood. Unfortunately, this situation has very grave maternal and fetal consequences. AFE can occur during labor, caesarean section, dilatation and evacuation or in the immediate postpartum period. The pathophysiology is believed to be immune mediated which affects the respiratory, cardiovascular, neurological and hematological systems. Undetected and untreated it culminates into fulminant pulmonary edema, intractable convulsions, disseminated intravascular coagulation (DIC), malignant arrhythmias and cardiac arrest. Definite diagnosis can be confirmed by identification of lanugo, fetal hair and fetal squamous cells (squames) in blood aspirated from the right ventricle. Usually the diagnosis is made clinically and by exclusion of other causes. The cornerstone of management is a multidisciplinary approach with supportive treatment of failing organs systems. Despite improved modalities for diagnosing AFE, and better intensive care support facilities, the mortality is still high.

Spectrum of Acute Viral Hepatitis in Southern India

BACKGROUND

The incidence of hepatitis-A among adults in India is on the decline as majority develops protective immunity to it by late adolescence. Most of these studies are from northern India. Clinical spectrum of sporadic acute viral hepatitis from southern India has not been well documented.

METHODS

A prospective hospital based study was conducted in a large military hospital in southern India. 224 consecutive patients with acute viral hepatitis were studied for their presentation, etiology and clinical features.

RESULT

Hepatitis-E was detected in 102 (45.4%), hepatitis A in 74 (33%) and hepatitis B in 28 (12.5%) patients. Acute hepatitis C was detected in two patients. 15 patients had a mixed infection. Hepatitis A constituted 41.2% and 31.3% of all cases in the age groups 11-20 and 21-30 years respectively. Cholestasis was present in 68 (30.4%) patients with hepatitis E accounting for most (61.8%) cases. There were four (1.8%) cases of acute liver failure. Two cases were due to hepatitis E and one case each was due to hepatitis A and hepatitis B. A relapsing course was seen in four cases due to hepatitis-A.

CONCLUSION

Hepatitis A remains a significant cause of sporadic acute viral hepatitis in young adults in southern India.

A comparison of neonatal surgical admissions between two linked surgical departments in Africa and Europe

Resources for neonatal surgery vary hugely between the developed countries and Africa. Due to the burden of other childhood diseases, neonatal surgery is of low priority to health-care budget holders in the developing countries. Admissions to two linked neonatal surgical institutions in Africa and Europe are compared to draw attention to the need of newborn care in developing countries. In a 3-year period, there have been 528 neonatal surgical admissions to the Kilimanjaro Christian Medical Centre (KCMC), Tanzania. During the same period, 707 surgical neonates were admitted to the John Radcliffe Hospital, UK (JRH). Conditions more commonly seen in the JRH include necrotising enterocolitis (NEC) (10.2 vs 0%), gastrochisis (5.5 vs 0.9%), congenital diaphragmatic hernia (2.4 vs 0.4%), congenital lung cysts (1.6 vs 0.4%), meconium ileus (2.4 vs 0%), malrotation (2.7 vs 0.6%) and abdominal/pelvic cysts (1.1 vs 0%). Conditions more commonly seen in KCMC include anorectal malformation (9.5 vs 4.7%), sacrococcygeal teratoma (2.3 vs 0.3%), Hirschsprung's disease (10.2 vs 4.5%), branchial fistula (0.9 vs 0%), haemangioma (2.1 vs 0%) and cystic hygroma (2.1 vs 1.0%). The spectrum of neonatal surgical admissions in our two institutions varied. We believe this is attributable to availability of antenatal diagnosis, primary health-care, transport facilities, genetics as well as survival of delayed presentation. This study demonstrates the extent and spectrum of neonatal surgical pathology in this part of Africa and highlights the need for newborn surgical care in developing countries.

Improvement of dry matter digestibility of water hyacinth by solid state fermentation using white rot fungi

Feeding value of water hyacinth biomass colonized by three species of white rot fungi during solid-state fermentation was investigated. All three organisms proved to be efficient degraders and enhanced dry matter digestibility. Loss of organic matter was maximum (23.6+/-0.1% dry wt) after 48 days by P. ostreatus. C. indica showed maximum cellulose degradation (18.5+/-0.1% dry wt) than other two fungi after 48 days of incubation. In all cases, an extensive removal of hemicellulose at the initial growth period and a delayed degradation of lignin were observed. Hemicellulolysis was maximum (46.3+/-0.1% dry wt) by C. indica, but delignification (14.2+/-0.2% dry wt) by P. sajor-caju after 48 days. The amount of reducing sugar in the degraded biomass decreased at early stages, but increased as degradation progressed in all three cases (maximum 1.1+/-0.05% dry wt after 48 days by C. indica). Soluble nitrogen content increased only during 16-32 days of incubation (highest 1.1+/-0.1% dry wt after 32 days by P. sajor-caju). Crude protein of the bioconverted biomass increased gradually up to 32 days but decreased thereafter (maximum 10.3+/-0.1% dry wt after 32 days by P. sajor - caju). Per cent change in in vitro dry matter digestibility of degraded substrates enhanced gradually after 8 days and reached maximum after 32 days but thereafter decreased (highest + 20.4+/-0.3% dry wt by P. sajor-caju). The results demonstrated the efficient degrading capacity of the test fungi and their potential use in conversion of water hyacinth biomass into mycoprotein-rich ruminant feed, more so by P. sajor-caju.

Palladium-copper catalyzed synthesis of benzofused heterocycles with two heteroatoms: novel and highly regio- and stereoselective syntheses of (E)-2-(2-arylvinyl)-3-tosyl-2,3-dihydro-1,3-benzothiazoles and (E)-2-alkyl(aryl)idene-3,4-dihydro-2H-1,4-benzothiazines

A highly novel, general, and convenient palladium and copper-catalyzed procedure has been developed for the synthesis of (E)-2-(2-arylvinyl)-3-tosyl-2,3-dihydro-1,3-benzothiazoles 28-40. 3-(2-Aminophenylthio)prop-1-yne 1 reacts with aryl iodides 2-14 under palladium-copper catalysis to yield the disubstituted alkynes 15-27 which after tosylation undergo a novel cyclization with CuI in the presence of triethylamine in THF to (E)-2-(2-arylvinyl)-3-tosyl-2,3-dihydro-1,3-benzothiazoles 28-40 rather than to the expected 3-alkylidene-4-tosyl-3,4-dihydro-2H-1,4-benzothiazines 41. The reaction is highly regio- and stereoselective. The synthesis of 2-(2-arylethyl)-3-tosylbenzothiazolines 42-47, 2-(2-arylvinyl)benzothiazoles 48-54, and a novel 5-substituted uracil derivative 55 of potential biological importance is also being reported. Similarly, the palladium-copper-catalyzed arylation of S-[2-(N-prop-2'-ynyl)aminophenyl]-N,N-dimethylthiocarbamate 58 with aryl iodides yields the disubstituted alkynes 59 which on cyclization with KOH in methanol leads to (E)-2-(2-aryl)methylidene-3,4-dihydro-2H-1,4-benzothiazines 61. The reaction of the diiodo compounds 12-14a, however, with 58 under palladium-copper-catalyzed reactions involves the participation of only one of the iodo groups in the heteroannulation process giving compounds 61i and 61j. These are amenable to further palladium-catalyzed reactions and afford polyunsaturated heteroaromatic compounds 62 and 63.

Rapid method for species-specific identification of Vibrio cholerae using primers targeted to the gene of outer membrane protein OmpW

The distribution of genes for an outer membrane protein (OmpW) and a regulatory protein (ToxR) in Vibrio cholerae and other organisms was studied using respective primers and probes. PCR amplification results showed that all (100%) of the 254 V. cholerae strains tested were positive for ompW and 229 ( approximately 98%) of 233 were positive for toxR. None of the 40 strains belonging to other Vibrio species produced amplicons with either ompW- or toxR-specific primers, while 80 bacterial strains from other genera tested were also found to be negative by the assay. These studies were extended with representative number of strains using ompW- and toxR-specific probes in DNA dot blot assay. While the V. cholerae strains reacted with ompW probe, only one (V. mimicus) out of 60 other bacterial strains tested showed weak recognition. In contrast, several strains belonging to other Vibrio species (e.g., V. mimicus, V. splendidus, V. alginolyticus, V. fluvialis, V. proteolyticus, V. aestuarianus, V. salmonicida, V. furnissii, and V. parahaemolyticus) showed weak to strong reactivity to the toxR probe. Restriction fragment length polymorphism analysis and nucleotide sequence data revealed that the ompW sequence is highly conserved among V. cholerae strains belonging to different biotypes and/or serogroups. All of these results suggest that the ompW gene can be targeted for the species-specific identification of V. cholerae strains. The scope of this study was further extended through the development of a one-step multiplex PCR assay for the simultaneous amplification of ompW and ctxA genes which should be of considerable value in the screening of both toxigenic and nontoxigenic V. cholerae strains of clinical as well as environmental origin.

(E)-2-[2-(1-Naphthyl)vinyl]-3-tosyl-2,3-dihydro-1,3-benzothiazole

The title compound, C(26)H(21)NO(2)S(2), which consists of a benzothiazole skeleton with alpha-naphthylvinyl and tosyl groups at positions 2 and 3, respectively, was prepared by palladium-copper-catalyzed heteroannulation. The E configuration of the molecule about the vinyl C=C bond is established by the benzothiazole-naphthyl C-C-C-C torsion angle of 177.5 (4) degrees. The five-membered heterocyclic ring adopts an envelope conformation with the Csp(3) atom 0.380 (6) A from the C(2)NS plane. The two S-C [1.751 (4) and 1.838 (4) A] and two N-C [1.426 (5) and 1.482 (5) A] bond lengths in the thiazole ring differ significantly.

Antibodies (IgG) to lipopolysaccharide of Vibrio cholerae O1 mediate protection through inhibition of intestinal adherence and colonisation in a mouse model

An antiserum raised against purified lipopolysaccharide (LPS) of a Vibrio cholerae O1 strain (Co366) induced passive protection against challenge with the parent as well as other O1 organisms but not against O139 or non-O1/non-O139 organisms. A considerable level of protection against O1 strains was also observed with the IgG fraction of the antiserum which inhibited intestinal adherence and colonisation. The monovalent Fab(IgG) fragment, on the other hand, showed only a low level of protection. Interestingly, purified LPS failed to inhibit intestinal colonisation by the parent strain (Co366), thereby suggesting that the cell surface LPS moieties of vibrios may not be directly involved in the colonisation process. It may be concluded that the anti-LPS antibodies induce passive protection through microagglutination and/or immobilisation of vibrios which do not allow the organisms to adhere to and colonise the intestine.

Molecular characterization of a new variant of toxin-coregulated pilus protein (TcpA) in a toxigenic non-O1/Non-O139 strain of Vibrio cholerae

A toxigenic non-O1/non-O139 strain of Vibrio cholerae (10259) was found to contain a new variant of the toxin-coregulated pilus (TCP) protein gene (tcpA) as determined by PCR and Southern hybridization experiments. Nucleotide sequence analysis data of the new tcpA gene in strain 10259 (O53) showed it to be about 74 and 72% identical to those of O1 classical and El Tor biotype strains, respectively. The predicted amino acid sequence of the 10259 TcpA protein shared about 81 and 78% identity with the corresponding sequences of classical and El Tor TcpA strains, respectively. An antiserum raised against the TCP of a classical strain, O395, although it recognized the TcpA protein of strain 10259 in an immunoblotting experiment, exhibited considerably less protection against 10259 challenge compared to that observed against the parent strain. Incidentally, the tcpA sequences of two other toxigenic non-O1/non-O139 strains (V2 and S7, both belonging to the serogroup O37) were determined to be almost identical to that of classical tcpA. Further, tcpA of another toxigenic non-O1/non-O139 strain V315-1 (O nontypeable) was closely related to that of El Tor tcpA. Analysis of these results with those already available in the literature suggests that there are at least four major variants of the tcpA gene in V. cholerae which probably evolved in parallel from a common ancestral gene. Existence of highly conserved as well as hypervariable regions within the sequence of the TcpA protein would also predict that such evolution is under the control of considerable selection pressure.

A new mycotoxin from Aspergillus candidus Link isolated from rough rice

A new mycotoxin (AcT1) was obtained from the mycelium of Aspergillus candidus Link isolated from rough rice stored under tropical conditions. AcT1 with the mol-formula C28H40O showed bright greenish blue fluorescence under uv (254 nm). The spectral and other characteristics indicated that the compound was a new one. The LD50 of the toxin on white rats was found to be 4.5 mg/Kg when injected intraperitoneally.

Acceptability and pathological changes in organs of rats fed wheat contaminated with a mixed culture of Aspergillus and Penicillium species

Mouldy grains can cause problems with pathological changes in vital organs. This investigation involved histological studies including the occurrence of fungal conidiospores in organs of rats fed wheat contaminated by the addition of a mixed culture of Aspergillus and Penicillium spp.