Immune imprinting and next-generation coronavirus vaccines

Vaccines based on historical virus isolates provide limited protection from continuously evolving RNA viruses, such as influenza viruses or coronaviruses, which occasionally spill over between animals and humans. Despite repeated booster immunizations, population-wide declines in the neutralization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have occurred. This has been compared to seasonal influenza vaccinations in humans, where the breadth of immune responses induced by repeat exposures to antigenically distinct influenza viruses is confounded by pre-existing immunity-a mechanism known as imprinting. Since its emergence, SARS-CoV-2 has evolved in a population with partial immunity, acquired by infection, vaccination or both. Here we critically examine the evidence for and against immune imprinting in host humoral responses to SARS-CoV-2 and its implications for coronavirus disease 2019 (COVID-19) booster vaccine programmes.

A computationally designed antigen eliciting broad humoral responses against SARS-CoV-2 and related sarbecoviruses

The threat of spillovers of coronaviruses associated with the severe acute respiratory syndrome (SARS) from animals to humans necessitates vaccines that offer broader protection from sarbecoviruses. By leveraging a viral-genome-informed computational method for selecting immune-optimized and structurally engineered antigens, here we show that a single antigen based on the receptor binding domain of the spike protein of sarbecoviruses elicits broad humoral responses against SARS-CoV-1, SARS-CoV-2, WIV16 and RaTG13 in mice, rabbits and guinea pigs. When administered as a DNA immunogen or by a vector based on a modified vaccinia virus Ankara, the optimized antigen induced vaccine protection from the Delta variant of SARS-CoV-2 in mice genetically engineered to express angiotensin-converting enzyme 2 and primed by a viral-vector vaccine (AZD1222) against SARS-CoV-2. A vaccine formulation incorporating mRNA coding for the optimized antigen further validated its broad immunogenicity. Vaccines that elicit broad immune responses across subgroups of coronaviruses may counteract the threat of zoonotic spillovers of betacoronaviruses.

Glycan masking of a non-neutralising epitope enhances neutralising antibodies targeting the RBD of SARS-CoV-2 and its variants

The accelerated development of the first generation COVID-19 vaccines has saved millions of lives, and potentially more from the long-term sequelae of SARS-CoV-2 infection. The most successful vaccine candidates have used the full-length SARS-CoV-2 spike protein as an immunogen. As expected of RNA viruses, new variants have evolved and quickly replaced the original wild-type SARS-CoV-2, leading to escape from natural infection or vaccine induced immunity provided by the original SARS-CoV-2 spike sequence. Next generation vaccines that confer specific and targeted immunity to broadly neutralising epitopes on the SARS-CoV-2 spike protein against different variants of concern (VOC) offer an advance on current booster shots of previously used vaccines. Here, we present a targeted approach to elicit antibodies that neutralise both the ancestral SARS-CoV-2, and the VOCs, by introducing a specific glycosylation site on a non-neutralising epitope of the RBD. The addition of a specific glycosylation site in the RBD based vaccine candidate focused the immune response towards other broadly neutralising epitopes on the RBD. We further observed enhanced cross-neutralisation and cross-binding using a DNA-MVA CR19 prime-boost regime, thus demonstrating the superiority of the glycan engineered RBD vaccine candidate across two platforms and a promising candidate as a broad variant booster vaccine.

A Multicenter Cohort Study From India of ABO-Incompatible Kidney Transplantation in Post-COVID-19 Patients

BACKGROUND

There is a dearth of data regarding the consequences of ABO-incompatible kidney transplant (ABOiKTx) among post-COVID-19 candidates.

METHODS

The study was designed as a retrospective, multicentric cohort study across 11 sites in India, from August 2020 to December 2021. The data for ABOiKTx conducted for post-COVID-19 candidates were investigated. The primary outcome of biopsy-proven acute rejection was compared with the ABO protocol implemented through Kaplan-Meier analysis. The secondary outcomes were graft loss, patient survival, and infections.

RESULTS

A total of 38 ABOiKTx with candidates of median (interquartile range) age of 38.5 (31.25-47.5) years were performed. Nineteen cases had mild COVID-19 severity, while 9 cases (23.6%) had an oxygen requirement. Six (15.7%) donors also were post-COVID-19. The most common ABO incompatibility reported was A to O in 14 (36.8%) pairs followed by B to O in 10 (26.3%) pairs. The maximum isoagglutinin titer cutoff was 1:2048 and 1:64 for baseline and pretransplant levels, respectively. The median time from COVID-19 infection to surgery was 130 (63.2-183) days. Biopsy-proven acute rejection, graft loss, and mortality were 13.1%, 2.6%, and 2.6%, respectively. The Breslow-Wilcoxon's P value in Kaplan-Meier plots were 0.57 and 0.93 for thymoglobulin-based induction and high dose rituximab-based regimen, respectively. The incidence of reinfection was 2.6%. Two (5.2%) urinary tract infections were reported. No cytomegalovirus or BK polyomavirus infection was reported. The median serum creatinine at 1 year of follow-up was 1.1 (0.8-1.3) mg/dL.

CONCLUSIONS

Our report implies that ABOiKTx in post-COVID-19 candidates can be successfully performed with no major deviation from standard ABO protocol.

Structures of distantly related interacting protein homologs are less divergent than non-interacting homologs

Homologous proteins can display high structural variation due to evolutionary divergence at low sequence identity. This classical inverse relationship between sequence identity and structural similarity, established many years ago, has remained true between homologous proteins of known structure over time. However, a large number of heteromeric proteins also exist in the structural data bank, where the interacting subunits belong to the same fold and maintain low sequence identity between themselves. It is not clear if there is any selection pressure to deviate from the inverse sequence-structure relationship for such interacting distant homologs, in comparison to pairs of homologs which are not known to interact. We examined 12,824 fold pairs of interacting homologs of known structure, which includes both heteromers and multi-domain proteins. These were compared with monomeric proteins, resulting in 26,082 fold pairs as a dataset of non-interacting homologous systems. Interacting homologs were found to retain higher structural similarity than non-interacting homologs at diminishing sequence identity in a statistically significant manner. Interacting homologs are more similar in their 3D structures than non-interacting homologs and have a preference towards symmetric association. There appears to be a structural constraint between remote homologs due to this commitment.

One-Year Outcomes with Use of Anti-T-Lymphocyte Globulin in Patients Undergoing Kidney Transplantation: Results from a Prospective, Multicentric, Observational Study from India

INTRODUCTION

Large-scale Indian data on the use of anti-T-lymphocyte globulin (ATLG) (Grafalon^®) as induction therapy in kidney transplantation (KT) patients is lacking. The aim of this study was to determine the 1-year patient and graft survival outcomes with the use of ATLG as induction regimen in KT.

METHODS

In a prospective, multicentric, observational study, adult patients who underwent ABO-compatible KT and had received ATLG as a part of induction were included in the study. The primary outcome measure was overall survival and death-censored graft survival at 12 months. The primary safety outcome was assessed by development of infectious complications and graft rejection.

RESULTS

In total, 359 patients were included in this study. The mean age was 42.77 ± 12.30 years and 83% were male. The average ATLG dose per patient was 6.2 ± 2.2 mg/kg whereas average cumulative dose per patient was 389.6 ± 149.8 mg. The rate of graft dysfunction was 13.4% of patients and 6.7% had biopsy-proven acute rejection (BPAR). There were a total of 12 (3.3%) deaths and one graft loss. Overall survival and death-censored graft survival at 12 months were 96.65% and 99.44%, respectively. The rate of infections was 13.6% with urinary tract infections being most common.

CONCLUSION

ATLG at an average dose of 6 mg/kg is an effective and safe induction regimen immunosuppressant for ABO-compatible KT with favourable impact on survival and graft function in Indian patients.

Ligand Docking Methods to Recognize Allosteric Inhibitors for G-Protein-Coupled Receptors

G-protein-coupled receptors (GPCRs) are membrane proteins which play an important role in many cellular processes and are excellent drug targets. Despite the existence of several US Food and Drug Administration (FDA)-approved GPCR-targeting drugs, there is a continuing challenge of side effects owing to the nonspecific nature of drug binding. We have investigated the diversity of the ligand binding site for this class of proteins against their cognate ligands using computational docking, even if their structures are known already in the ligand-complexed form. The cognate ligand of some of these receptors dock at allosteric binding site with better score than the binding at the conservative site. Interestingly, amino acid residues at such allosteric binding site are not conserved across GPCR subfamilies. Such a computational approach can assist in the prediction of specific allosteric binders for GPCRs.

A Case of Hearing Impairment with Renal Dysfunction

Hearing impairment in a patient with renal failure is an important clue towards etiologic diagnosis of kidney disease. Variety of hereditary diseases, developmental defects, and toxins involve these two organs. However, additional retinopathy is seen in quite a few diseases which include Alport's syndrome and Muckle–Wells syndrome (MWS). We are reporting a case of middle-aged woman with childhood-onset of hearing impairment who presented with renal failure and was diagnosed to have renal amyloidosis on kidney biopsy but without any light chain restriction. During evaluation for live donor kidney transplant, her brother was also found to have hearing impairment and retinopathy however with normal renal function and urinalysis. Genetic testing of both of them was done for panel of mutations related to hereditary amyloidosis which revealed NLRP3 mutation in both. This mutation is characteristic of MWS which can lead to secondary amyloidosis and renal failure.

Diffuse large B-cell lymphoma in elderly: Experience from a tertiary care oncology center in South India

Introduction:

Diffuse large B-cell lymphoma (DLBCL) is the most frequent non-Hodgkins lymphoma in the elderly. With the rising proportion of older persons in India, it is important to study current patterns and management of this disease, given that data in this regard are scarce in Indian settings. The aim of this study was to document the clinical features of DLBCL among elderly patients and their outcome over 7 years at a tertiary care oncology center.

Materials and Methods:

This was a retrospective records review of 119 DLBCL cases between January 2007 and January 2015 aged 60 years and above done at Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India. Clinical staging was done according to Ann Arbor staging as modified by Cotswold's and International Prognostic Index (IPI) calculated.

Results:

The mean age was 69.54 years (±5.44) with male: female ratio of 1.52:1. B symptoms were seen in 33% of patients. Thirty-six percent of the patients had stage II disease. The advanced stage was seen in 12% and bulky disease in 9.5%. Bone marrow was involved in 12%. The most common extranodal site was the head and neck region. The distribution according to the IPI was as follows: Low risk 38 (31.93%), low-intermediate risk 53 (44.54%), high-intermediate risk 20 (16.80%), and high risk 8 (6.72%). Among 119 patients, 98 (64.7%) received treatment with either combination of rituximab, cyclophosphamide, adriamycin, vincristine, epirubicin, and prednisolone. Overall response rate was 63.26% with a complete response rate of 38.77%. The overall survival ranged from 2 to 123 months with the median being 9.5 months.

Conclusion:

In elderly, DLBCL is common in seventh decade and most of them present in an early stage and low IPI. The incorporation of rituximab to anthracycline based chemotherapy shows a significant improvement in survival in elderly DLBCL.

Is balloon-assisted maxillary sinus floor augmentation before dental implant safe and promising? A systematic review and meta-analysis

We aimed to assess the complications of minimally invasive balloon-assisted maxillary sinus floor augmentation, compared with the conventional sinus floor augmentation procedures done before placing a dental implant. A structured question was formulated and an electronic search was conducted in three databases (MEDLINE via PubMed, Google Scholar, and Scopus). A separate search of gray literature and a hand search for missing articles were also conducted. Apart from animal studies, in-vitro studies, and case reports, all other types of studies where maxillary sinus floor augmentation was done using a balloon were considered for review. Our review was registered in International Prospective Registration of Systematic Reviews (PROSPERO) under number CRD42018086770. Our search produced 73 articles. However, only eight articles were found eligible to be included in our review (seven case series and one case-control study). Quality check was done using Methodological Index for Non-Randomized Studies (MINORS). Results suggest that balloon-assisted augmentation is associated with low rates of membrane tears (9 out of 272 sinus augmentation attempts), and high follow-up bone gain levels (mean 212.91%, 95% confidence interval 158.07%-267.75%, I2 = 97.62%). Balloon-assisted augmentation seems to be safe. More clinical trials are needed to assess the advantages and disadvantages of balloon-assisted maxillary sinus floor augmentation compared with other procedures.

Mechanism of CcdA-Mediated Rejuvenation of DNA Gyrase

Most biological processes involve formation of transient complexes where binding of a ligand allosterically modulates function. The ccd toxin-antitoxin system is involved in plasmid maintenance and bacterial persistence. The CcdA antitoxin accelerates dissociation of CcdB from its complex with DNA gyrase, binds and neutralizes CcdB, but the mechanistic details are unclear. Using a series of experimental and computational approaches, we demonstrate the formation of transient ternary and quaternary CcdA:CcdB:gyrase complexes and delineate the molecular steps involved in the rejuvenation process. Binding of region 61-72 of CcdA to CcdB induces the vital structural and dynamic changes required to facilitate dissociation from gyrase, region 50-60 enhances the dissociation process through additional allosteric effects, and segment 37-49 prevents gyrase rebinding. This study provides insights into molecular mechanisms responsible for recovery of CcdB-poisoned cells from a persister-like state. Similar methodology can be used to characterize other important transient, macromolecular complexes.

Clinicoepidemilogical Correlation of BRCA 1 and 2 Mutations in Carcinoma Ovary - an Indian Perspective

Introduction: All over the world in 2008, approximately 225,000 women were diagnosed with ovarian cancer, and 140,000 died from this disease.1 Ovarian cancer is the second-most common gynecologic malignancy in the developed countries. In the developing countries, it is the third-most common gynecologic malignancy after breast and cervical cancer with an incidence of 5.0/100,000 and a mortality rate of 3.1/100,000. Women with BRCA1 gene mutations typically develop ovarian cancer at an earlier age than other women, with an average age at diagnosis of 50-year-old while for patients with BRCA2 mutation carriers it is 60 years, similar to the general population. Aim and Objective: The aim of this study is to study the incidence, clinical profile, and outcomes of a patient with BRCA 1 and BRCA 2 mutation in carcinoma ovary and its comparison with patients without mutation. Results: Out of total 50 patients, 45 (90%) were BRCA negative and rest fi ve (10%) were BRCA positive. Of the five patients, only two (4% of total) had pathological mutations while the rest of three patients had benign mutations only. Overall median age of presentation was 61 years for BRCA-negative patients and 38 years for BRCA-positive patients. Most of the patients presented in Stage III (23 out of 50; 46%), while the second-most common presentation was in Stage IV (34%). In our study, we had an overall mortality of one patient who was BRCA negative, in Stage IV while no mortality was noted in BRCA positive subset of patients. Conclusion: This was a single center-based and spanned over 24 months involving limited number of patients with ovarian cancer with maximum follow-up for 9 months.

Fold combinations in multi-domain proteins

Domain-domain interactions in multi-domain proteins play an important role in the combined function of individual domains for the overall biological activity of the protein. The functions of the tethered domains are often coupled and hence, limited numbers of domain architectures with defined folds are known in nature. Therefore, it is of interest to document the available fold-fold combinations and their preference in multi-domain proteins. Hence, we analyzed all multi-domain proteins with known structures in the protein databank and observed that only about 860 fold-fold combinations are present among them. Analyses of multi-domain proteins represented in sequence database result in recognition of 29,860 fold-fold combinations and it accounts for only 2.8% of the theoretically possible 1,036,080 (1439C2) fold-fold combinations. The observed preference for fold-fold combinations in multi-domain proteins is interesting in the context of multiple functions through structural adaptation by gene fusion.

Occult Gallbladder Carcinoma Presenting as a Primary Ovarian Tumour: a Case Report and Review of Literature

The ovary is a common site of metastasis from various organs. However, little is known about gallbladder carcinoma metastasising to the ovaries and presenting as a primary ovarian tumour. We report a case of a metastatic gallbladder carcinoma which mimicked a primary ovarian tumour in a 31-year-old woman who presented with menstrual symptoms and an ovarian mass without obvious signs and symptoms related to gallbladder carcinoma. Postoperatively histopathological examination diagnosed primary ovarian germ cell tumour for further chemotherapy. However, postoperative re-evaluation with radiology suggested the possibility of a primary gallbladder carcinoma. Exact diagnosis could only be made after repeat histopathological evaluation of the ovarian mass.

Microsatellite instability in stage II colorectal cancer: An Indian perspective

INTRODUCTION

Around 80% of colorectal carcinoma are associated with chromosomal instability (CIN) while rest of 20 % are euploid, possessing defect in mis match repair system (MMR) quintessential for surveillance and correction of errors in introduced into microsatellites.

MATERIALS AND METHODS

We analyse all stage II CRC for MSI who presented at MDTC at Army hospital (research and refrral) new delhi during last 2 years (Jan 14 to Dec 2015).

RESULTS

We found that 22.2% patients out of 45 patients with stageII CRC being MSI-. high. We also noticed all suchcases were associated with loss of expression of PMS2 & MLH1, that was in contrast other studies where loss of MLH1 and MSH@, MSH6 were seen more commonly.

CONCLUSION

MSI occurs in a significant proportion of colorectal cancers in young (<50 years old) patients. Young age at colorectal cancer diagnosis, proximal tumor location, family history of colorectal cancer were independent predictors of MSI status in our patients. In a proportion of these young patients with MSI tumors, loss of expression of proteins by 2 MMR genes PMS2 and hMLH1 has been identified.

Same but not alike: Structure, flexibility and energetics of domains in multi-domain proteins are influenced by the presence of other domains

The majority of the proteins encoded in the genomes of eukaryotes contain more than one domain. Reasons for high prevalence of multi-domain proteins in various organisms have been attributed to higher stability and functional and folding advantages over single-domain proteins. Despite these advantages, many proteins are composed of only one domain while their homologous domains are part of multi-domain proteins. In the study presented here, differences in the properties of protein domains in single-domain and multi-domain systems and their influence on functions are discussed. We studied 20 pairs of identical protein domains, which were crystallized in two forms (a) tethered to other proteins domains and (b) tethered to fewer protein domains than (a) or not tethered to any protein domain. Results suggest that tethering of domains in multi-domain proteins influences the structural, dynamic and energetic properties of the constituent protein domains. 50% of the protein domain pairs show significant structural deviations while 90% of the protein domain pairs show differences in dynamics and 12% of the residues show differences in the energetics. To gain further insights on the influence of tethering on the function of the domains, 4 pairs of homologous protein domains, where one of them is a full-length single-domain protein and the other protein domain is a part of a multi-domain protein, were studied. Analyses showed that identical and structurally equivalent functional residues show differential dynamics in homologous protein domains; though comparable dynamics between in-silico generated chimera protein and multi-domain proteins were observed. From these observations, the differences observed in the functions of homologous proteins could be attributed to the presence of tethered domain. Overall, we conclude that tethered domains in multi-domain proteins not only provide stability or folding advantages but also influence pathways resulting in differences in function or regulatory properties.

High prevalence of multi-domain proteins in proteomes has been attributed to higher stability and functional and folding advantages of the multi-domain proteins. Influence of tethering of domains on the overall properties of proteins has been well studied but its influence on the properties of the constituent domains is largely unaddressed. Here, we investigate the influence of tethering of domains in multi-domain proteins on the structural, dynamics and energetics properties of the constituent domains and its implications on the functions of proteins. To this end, comparative analyses were carried out for identical protein domains crystallized in tethered and untethered forms. Also, comparative analyses of single-domain proteins and their homologous multi-domain proteins were performed. The analyses suggest that tethering influences the structural, dynamic and energetic properties of constituent protein domains. Our observations hint at regulation of protein domains by tethered domains in multi-domain systems, which may manifest at the differential function observed between single-domain and homologous multi-domain proteins.

Microsatellite Instability in Stage II and III Colorectal Cancer: Patterns and Profile

Introduction: Around 80% of colorectal carcinoma are associated with chromosomal instability while rest of 20% are euploid, possessing defect in mismatch repair system (MMR) quintessential for surveillance and correction of errors introduced into microsatellites. The microsatellite instability (MSI) phenotype has three major clinical applications: prognosis of colorectal cancer (CRC), prediction of response to 5 fluorouracil, and irinotecan, and genetic assessment of Lynch syndrome. Materials and Methods: We analyzed all Stage II and Stage III colorectal cancer (CRC) for MSI, who presented at Army Hospital, Research and Referral, New Delhi, from January 2014 to December 2016. Although patients of Stage II CRC were taken throughout the study period, Stage III CRC was included in last 1½ years to compare the prevalence of MSI in these two subsets of patients. Results: 26.2% of Stage II and 11.3% of Stage III patients were found to be MSI-high (MSI-H) (P = 0.04). Nineteen (86%) of 22 MSI-H patients were below 30 years of age (P = 0.01). Of 22 MSI-H patients, 18 had right-sided tumors (P = 0.03) and only three patients had rectal tumors. Most common pattern of MSI-H tumors was loss of expression of MLH1 and PMS2, seen in 15 of 16 (88%) of Stage II and three of 6 (50%) of Stage III CRC (P = 0.04). Conclusion: We conclude higher prevalence of MSI-H tumors in Stage II, as compared to Stage III CRC, which was demonstrated slightly higher in our study compared to published literature. MSI-H tumors tend to occur with high frequency in younger population, with right-sided colonic tumors, histopathology characterized by mucinous subtype with high prevalence of tumor infiltrating lymphocytes. Loss of expression of two MMR proteins, namely, PMS2 and MLH1 has been identified in most of MSI-H patients of our study, of which 86% were <30 years of age. This is in contrast to observation in previous studies where loss of PMS2 and MLH1 proteins was observed in older (>70 years) patients with MSI-H tumors, and in younger patients, MSI-H status was associated with loss of MLH1, MSH2, and MSH6.

Specificity and stability of transient protein-protein interactions

Remarkable features that are achieved in a protein-protein complex to precise levels are stability and specificity. Deviation from the normal levels of specificity and stability, which is often caused by mutations, could result in disease conditions. Chemical nature, 3-D arrangement and dynamics of interface residues code for both specificity and stability. This article reviews roles of interfacial residues in transient protein-protein complexes. It is proposed that aside from hotspot residues conferring stability to the complex, a small set of 'rigid' residues at the interface that maintain conformation between complexed and uncomplexed forms, play a major role in conferring specificity. Exceptionally, 'super hotspot' residues, which confer both stability and specificity, are attractive sites for interaction with small molecule inhibitors.

Spectrum of renal involvement in hematolymphoid neoplasms: Renal biopsy findings of 12 cases

Spectrum of causes for renal dysfunction in patients with hematolymphoid malignancy (excluding plasma cell dyscrasia) is varied. A retrospective evaluation of “native” renal biopsies referred to our institute during the period from January 2010 to December 2013 revealed 12 cases. Age ranged between 7 and 69 (median 54.5) years. All patients were males. The neoplasms included non-Hodgkin lymphoma, chronic lymphocytic leukemia, acute lymphoblastic leukemia, Burkitt's lymphoma, intravascular lymphoma, Hodgkin lymphoma and chronic myeloid leukemia. Proteinuria was noted in 66% of the patients (nephrotic range in 5, subnephrotic range in 3). Renal insufficiency was noted in 100% patients. Malignancy-related kidney injury was noted in 75% of the cases. Renal histology showed lymphomatous infiltration (8), membranoproliferative glomerulonephritis (MPGN) (3), intracapillary monoclonal deposit disease (1) and intravascular lymphoma (1). Distribution of lymphomatous infiltration was diffuse in 50% and focal in 50%. We observed that renal dysfunction was predominantly a direct effect, that is, lymphomatous invasion. Paraneoplastic glomerulopathic changes occur in the form of MPGN. Proteinuria of >2 g/day correlated with glomerular disease.

IgG4 related renal disease: A wolf in sheep's clothing

IgG4 related disease is a fibro-inflammatory condition with involvement of renal and extra renal organs, characterized by lymphoplasmacytic infiltration with organ dysfunction. We describe three cases of IgG4 related renal disease from a tertiary care hospital in south India.

P02-270 “Education, education, education-” adult liaison psychiatry (consultation-liaison): Can service development fulfil educational needs?

Introduction

Liaison Psychiatry is primarily concerned with the detection and treatment of psychiatric disorders within the general hospitals. 1A study2 also highlighted the presence of only 45.5 core trainee posts in this speciality nationally.

Aims & objective

To survey the liaison psychiatry service recently set up as a service provision at a psychiatry unit in North Derbyshire.

Methods

We retrospectively reviewed all case notes of patients who had been assessed from January 2007 to June 2009 by the consultation-liaison service.

Results

A total of 136 patients had been assessed since this service began in September 2007. Majority of the patients (72%) were between the ages of 31 to 65 years, while the gender was equally distributed. 51% were referred from the medical ward and most of them had been referred by core trainee. 95% of the referral was during working hours and 74% of the patients were assessed within 24 hours. Their diagnosis was variable, for e.g. 29% had depression, 19% had substance misuse problems, 8% had psychosis etc. 66% of patients were managed by medication advice, psycho-education and referral to CMHT/GP.

Conclusions

Liaison psychiatry was established for service provision, but it is apparent that it fulfilled both clinical and educational needs, despite the challenges. Adequate experience can be gained with a well supervised service. The overall educational value of designing and implementing a new service as a trainee cannot be overstated; it is something which is difficult to learn in classrooms.

Melioidosis in southern India: epidemiological and clinical profile

Melioidosis, which is mainly prevalent in Thailand and Australia, has shown an increasing trend in India in the last few years. We carried out a retrospective study of 25 culture-proven adult cases of melioidosis who were admitted to a tertiary care hospital in southern India during June 2001 to September 2007. There was a six-fold increase in the number of cases in 2006 and 2007 as compared to 2001. Diabetes mellitus was the predisposing factor in 68% of cases, followed by alcoholism (28%). The clinical presentations were fever (80%), pneumonia and/or pleural effusion (48%), hepatomegaly (56%), joint involvement, and/or osteomyelitis (48%), splenomegaly (40%), splenic abscess (24%) and septicemia (28%). The organism, Burkholderia pseudomallei, was sensitive to co-amoxiclav, cotrimoxazole, ceftazidime, and carbapenem. The study suggests that melioidosis is an emerging infectious disease in the southwestern coastal belt of India, and it is likely to happen at much higher incidence.

Syndromic management of vaginal discharge among women in a reproductive health clinic in India

OBJECTIVES

To examine the performance of the syndromic approach in the management of vaginal discharge among women attending a reproductive health clinic in New Delhi, India.

METHODS

Women who sought services from the clinic and who had a complaint of vaginal discharge were interviewed, underwent a pelvic examination, and provided samples for laboratory investigations of bacterial vaginosis, candidiasis, syphilis, trichomoniasis, and Chlamydia trachomatis and Neisseria gonorrhoeae infections. Data analysis focused on the prevalence of infection and on the performance of the algorithm recommended by the national authorities for the management of vaginal discharge.

RESULTS

The most common infection among 319 women was bacterial vaginosis (26%). At least one sexually transmitted infection was detected in 21.9% of women. The prevalence of C trachomatis infection was 12.2%; trichomoniasis 10%; syphilis 2.2%; N gonorrhoeae was not isolated. An algorithm based on risk assessment and speculum assisted clinical evaluation was not helpful in predicting cervical infections associated with C trachomatis (sensitivity 5% and PPV 9%). This algorithm was sensitive (95%) though not specific (22%) in selecting women for metronidazole therapy effective against bacterial vaginosis or trichomoniasis, and overtreatment was a problem (PPV 38%). The sensitivity, specificity, and PPV of this algorithm for the treatment of candidiasis were 46%, 98%, and 88% respectively. The cost per case assessed using the algorithm was $2 and the cost per infection correctly treated was $4.25.

CONCLUSIONS

The prevalence of cervical infection associated with C trachomatis was high among these "low risk" women. The syndromic approach is not an efficient tool for detecting this condition, and alternative approaches to evaluation and intervention are required. The syndromic management of vaginal discharge among women seeking family planning and other reproductive health services should focus on vaginal infections, thus enhancing quality of care and addressing women's concerns about their health.

Antigenic relationships among the rickettsiae of the spotted fever and typhus groups

Using immunoblots to analyze antigenic relationships among the pathogenic spotted fever and typhus group rickettsiae, I found that the rickettsial lipopolysaccharide (LPS) was a group-specific antigen. All the rickettsiae examined had 135-kDa and 58-kDa protein antigens. The spotted fever rickettsiae and Rickettsia canada had, in addition, 190-kDa protein antigens which were antigenic analogs of previously described protective antigens of R. conorii and R. rickettsii.

A recombinant Rickettsia conorii vaccine protects guinea pigs from experimental boutonneuse fever and Rocky Mountain spotted fever

There are no vaccines against boutonneuse fever and Rocky Mountain spotted fever. Previous studies have identified a Rickettsia rickettsii surface protein as a vaccine candidate and shown that an antigenically related protein is present in R. conorii, which causes boutonneuse fever. The gene encoding the R. rickettsii protein has been cloned and expressed in Escherichia coli. We confirmed by 7.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis of rickettsial lysates followed by immunoblotting with a monoclonal antibody raised against the R. rickettsii protein that an analogous protein exists in R. conorii. Although these proteins were previously called 155-kilodalton (kDa) proteins, we found that their apparent molecular masses were 198 kDa for R. conorii Kenya tick typhus and 190 kDa for R. rickettsii R. Using the R. rickettsii gene probe, we cloned and expressed a 5.5-kilobase HindIII fragment from R. conorii Kenya tick typhus genomic DNA in E. coli JM107. The expressed recombinant product was recognized by a monospecific polyclonal rabbit antiserum prepared against the 198-kDa protein. Guinea pigs immunized with sonic lysates of the E. coli strain expressing the recombinant gene product developed antibodies recognizing R. conorii when tested by a microimmunofluorescence antibody assay. Upon immunoblotting of rickettsial lysates, those antisera specifically recognized the 198-kDa R. conorii protein and its 190-kDa analog in R. rickettsii. Guinea pigs immunized with sonic lysates of the recombinant E. coli expressing the 198-kDa protein were protected from experimental infections with the homologous R. conorii strain and partially protected from experimental infections with a strain of the heterologous species R. rickettsii. These findings show that the 198-kDa R. conorii protein is a candidate for a vaccine against boutonneuse fever.

Respiratory-mucin inhibition of the opsonophagocytic killing of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a frequent respiratory tract colonizer in diseases in which mucociliary clearance is defective. The most striking of these is cystic fibrosis. The reasons for this organism's ability to colonize the respiratory tract and to persist there are not fully understood. Earlier studies showed that P. aeruginosa adheres preferentially to tracheobronchial mucin when compared with enterobacteria. We reasoned that if adherence to respiratory mucin protected P. aeruginosa from opsonophagocytic killing, then the ability of this organism to chronically colonize the respiratory tract could be partially explained. Using an opsonophagocytic killing assay with human polymorphonuclear leukocytes, we found that respiratory mucin protected six strains of P. aeruginosa from opsonophagocytic killing but did not protect poorly adhering strains of Escherichia coli, Staphylococcus aureus, or group B streptococci. Incubating P. aeruginosa with the mucin prior to addition to the opsonic assay inhibited phagocytic killing, whereas incubation of polymorphonuclear leukocytes with mucin did not, suggesting that inhibition was not due to an effect of mucin on leukocytes per se but was a consequence of bacterial adherence to mucin. Further studies indicated no decrease in the binding of either antibody or complement component C3 to the bacterial surface in the presence of mucin. This suggests that phagocytic inhibition may be due to a defect in uptake or destruction of mucin-coated bacteria by the leukocytes. Thus, the adherence of P. aeruginosa to respiratory mucin potentially contributes to its persistence in the respiratory tract by interfering with host immune responses.

Lipopolysaccharide phase variation determines the complement-mediated serum susceptibility of Coxiella burnetii

Phase variation of Coxiella burnetii is due to variation of the lipopolysaccharide (LPS), a phenomenon analogous to smooth-to-rough LPS variation of gram-negative enteric bacteria. Virulent enterobacteria usually have a smooth LPS and resist serum killing, whereas avirulent rough LPS mutants are sensitive to complement-mediated serum killing. Like gram-negative enterobacteria, smooth LPS phase variants of C. burnetii are virulent, whereas the rough LPS variants are avirulent. We therefore studied the effects of human serum on the LPS variants of the Nine Mile strain of C. burnetii. Analogous to gram-negative enterobacteria, the smooth and intermediate LPS C. burnetii phase variants were resistant to complement-mediated serum killing, whereas the rough LPS variants were killed by serum complement. Although the smooth and intermediate LPS variants were serum resistant, they differed in their interactions with the complement system. The smooth LPS variant activated complement poorly and did not bind C3b; however, the intermediate LPS variant activated complement and bound C3b. The rough LPS variant activated complement via the alternative pathway, whereas the intermediate LPS variant activated the classical pathway. These results provide an explanation for the avirulent nature of the rough LPS variant of C. burnetii and suggest that differences in C. burnetii LPS structure influence the interactions of the LPS phase variants with the complement system.

Why is Pseudomonas the colonizer and why does it persist?

Pseudomonas aeruginosa is currently the major cause of morbidity and mortality in cystic fibrosis. Studies to understand why this particular organism is a problem and why host defenses fail to clear it, are beginning to provide some answers. Implicit in any working hypothesis are the prerequisites that: (i) P. aeruginosa should have a tropism for the respiratory tract; (ii) there should be a physical clearance defect; and (iii) there should be an acquired immune clearance defect. Studies from many laboratories support these contentions. This organism exhibits its tropism by adhering to tracheal cells and to tracheobronchial mucins by means of pili or the mucoid exopolysacharide of mucoid strains. The receptors on both cells and mucins contain sialic acid as the dominant sugar moiety. Many factors contribute to its persistence, chief among which is the failure of phagocytic defenses caused by microbial or host enzymes and even by mucins which inhibit the opsonophagocytosis of P. aeruginosa. Injury to the mucociliary system, again caused by microbial or host factors, is also a prominent factor in the persistence of P. aeruginosa. We hypothesize that this organism is the dominant pathogen because of the existence of receptors in the respiratory tract for it and that it persists because bacteria in stagnant mucus cannot be cleared physically or immunologically. We are doubtful that conventional vaccination approaches will yield a solution to this problem.

Effects of subminimal inhibitory concentrations of antibiotics on the adherence of Pseudomonas aeruginosa to tracheobronchial mucin

Bacterial adherence to mucins may be important in tracheobronchial infections in cystic fibrosis. Sublethal concentrations of antibiotics reduce bacterial adherence to epithelial cells and mucins. This reduction in adherence may be a component of antimicrobial effects in infections at anatomical sites where bactericidal concentrations of antibiotics are difficult to achieve. We therefore tested the effects of sublethal concentrations of an aminoglycoside, tobramycin, and a beta-lactam antibiotic, ceftazidime, on the adherence of Pseudomonas aeruginosa to tracheobronchial mucin, since mucus secretions are often colonized by P. aeruginosa in cystic fibrosis. Adherence of the mucoid strains tested was inhibited by ceftazidime, but not by tobramycin. This effect of ceftazidime may partially explain its efficacy in patients with cystic fibrosis despite variables achieved in sputum.

Adherence of Pseudomonas aeruginosa to human tracheobronchial mucin

A microtiter plate assay was developed to study the adherence of Pseudomonas aeruginosa to purified human tracheobronchial mucin. The wells of the plates were treated with silicon to minimize nonspecific binding of bacteria and then coated with a solution of purified human tracheobronchial mucin. Bacteria were added to the wells, and the plates were incubated at 37 degrees C. The wells were washed 15 times in an automated microtiter plate washer, and the bacteria bound to wells were desorbed with Triton X-100 and plated for enumeration. Scanning electron microscopy verified bacterial adherence to the mucin-coated wells and desorption of bacteria by Triton X-100. Adherence of P. aeruginosa increased as the concentration of mucin used to coat the wells was increased, with saturation occurring at 0.5 microgram of mucin protein per ml. Other parameters that affected adherence included the time of incubation and concentration of bacteria. Similar studies with strains of Escherichia coli and Klebsiella pneumoniae indicated a relative lack of binding of these bacteria to mucin. In comparing different strains of P. aeruginosa, there were small differences in binding between strains. It is inferred that there may be specific sites on human tracheobronchial mucin which facilitate this preferential binding.

Strongyloides infection and meningitis in an immunocompromised host

Strongyloidiasis and aseptic meningitis occurred in a renal transplant recipient who was receiving immunosuppressive drugs. Cure followed therapy with antibiotic administration for 3 days combined with oral thiabendazole, suggesting parasitic infection as the most likely cause of meningitis. Awareness of this disease and need for prompt institution of therapy is stressed. Prophylactic administration of thiabendazole is probably preventive.