Exogenous GABA supplementation to facilitate Cr (III) tolerance and lipid biosynthesis in Chlorella sorokiniana

Microalgae possess the prospective to be efficiently involved in bioremediation and biodiesel generation. However, conditions of stress often restrict their growth and diminish different metabolic processes. The current study evaluates the potential of GABA to improve the growth of the microalga Chlorella sorokiniana under Cr (III) stress through the exogenous administration of GABA. The research also investigates the concurrent impact of GABA and Cr (III) stress on various metabolic and biochemical pathways of the microalgae. In addition to the control, cultures treated with Cr (III), GABA, and both Cr (III) and GABA treated were assessed for accurately analysing the influence of GABA. The outcomes illustrated that GABA significantly promoted growth of the microalgae, resulting in higher biomass productivity (19.14 mg/L/day), lipid productivity (3.445 mg/L/day) and lipid content (18%) when compared with the cultures under Cr (III) treatment only. GABA also enhanced Chl a content (5.992 μg/ml) and percentage of protein (23.75%). FAMEs analysis by GC-MS and total lipid profile revealed that GABA treatment can boost the production of SFA and lower the level of PUFA, a distribution ideal for improving biodiesel quality. ICP-MS analysis revealed that GABA supplementation could extend Cr (III) mitigation level up to 97.7%, suggesting a potential strategy for bioremediation. This novel study demonstrates the merits of incorporating GABA in C. sorokiniana cultures under Cr (III) stress, in terms of its potential in bioremediation and biodiesel production without disrupting the pathways of photosynthesis and protein production.

Heavy metal tolerance in microalgae: Detoxification mechanisms and applications

The proficiency of microalgae to resist heavy metals has potential to be beneficial in resolving various environmental challenges. Global situations such as the need for cost-effective and ecological ways of remediation of contaminated water and for the development of bioenergy sources could employ microalgae. In a medium with the presence of heavy metals, microalgae utilize different mechanisms to uptake the metal and further detoxify it. Biosorption and the next process of bioaccumulation are two such major steps and they also include the assistance of different transporters at different stages of heavy metal tolerance. This capability has also proved to be efficient in eradicating many heavy metals like Chromium, Copper, Lead, Arsenic, Mercury, Nickel and Cadmium from the environment they are present in. This indicates the possibility of the application of microalgae as a biological way of remediating contaminated water. Heavy metal resistance quality also allows various microalgal species to contribute in the generation of biofuels like biodiesel and biohydrogen. Many research works have also explored the capacity of microalgae in nanotechnology for the formation of nanoparticles due to its relevant characteristics. Various studies have also revealed that biochar deduced from microalgae or a combination of biochar and microalgae can have wide applications specially in deprivation of heavy metals from an environment. This review focuses on the strategies adopted by microalgae, various transporters involved in the process of tolerating heavy metals and the applications where microalgae can participate owing to its ability to resist metals.

1226 A MULTI-DISCIPLINARY APPROACH TO TRANSFORMING EYE CARE SERVICES FOR CARE HOME RESIDENTS

Introduction

Care home residents can have variable access to eye care services and treatments. We developed a collaborative approach between optometrists, care homes, and primary and secondary care to enable personalised patient-centred care.

Objective

To develop and evaluate an integrated model of eye care for care home residents.

Methods

Small scale plan-do-study-act (PDSA) service tests were completed in three care-homes in Southwark (2 residential, 1 nursing) between November 2021 to May 2022. Processes were compared to historical feedback and hospital-based ophthalmology clinic attendances (Mar 2019-2020). Hospital-like assessments were piloted at two care homes for feasibility and acceptability. Further piloting utilised usual domiciliary optometry-led assessment with multidisciplinary meeting access (including optometrist, GP, geriatrician, ophthalmologist and care home nurse) to reduce duplication of assessments and to evaluate MDM processes and referral rates.

Results

Examination was 100% successful at home (visual acuity and pressure measurement) compared to hospital outpatients (71.7% success visual acuity, 54.5% pressures). Examination was faster than in hospital settings (16 minutes vs 45 minutes-1 hour). Residents were away from usual activities for 32 minutes vs 6 hours for hospital visits including transport. Residents were less distressed with home-based assessments. Did-Not-Attend (DNA) rates reduced (26.7% to 0%), secondary care discharge rates improved (8.4% to 32%). Hospital eye service referral were indicated in 19% -23%, half of which were for consideration of cataract surgery. Alternative conservative plans were agreed at MDM for nursing home residents who were clinically too frail or would not have been able to comply with treatments avoiding 33% unnecessary referrals.

Conclusions

Home-based eye care assessments appear better tolerated and are more efficient for residents, health and care staff. Utilising an MDM for optometrists to discuss residents with ophthalmologists and wider MDT members enabled personalised patient-centred decision-making. Future work to test this borough wide is in progress.

AB0434 EFFICACY AND SAFETY OF OBINUTUZUMAB IN SYSTEMIC LUPUS ERYTHEMATOSUS PATIENTS WITH SECONDARY NON-RESPONSE TO RITUXIMAB

Background

Secondary inefficacy characterized by infusion reactions and anti-drug antibodies occur in 14% of SLE patients treated with repeat rituximab courses(1). Obinutuzumab is a next-generation humanized type-2 anti-CD20 therapy licensed for hematological malignancies which may overcome this issue(2).

Objectives

We set out to evaluate the clinical efficacy and safety of obinutuzumab in a cohort of rituximab resistant SLE patients.

Methods

We collated data from SLE patients receiving obinutuzumab for secondary non-response to rituximab in BILAG centres. Disease activity was assessed using BILAG-2004, SLEDAI-2K and serology before, and 6 months after, obinutuzumab 2x1000mg infusions alongside methylprednisolone 100mg. Flow cytometry where possible was carried out using a multiple gating highly sensitive strategy.

Results

All 9 patients included in the study received obinutuzumab alongside concomitant oral immunosuppression. At 6 months post-obinutuzumab, there were significant reductions in median SLEDAI-2K from 12 to 6 (p=0.014) and total BILAG-2004 score from 21 to 2 (p=0.009). Complement C3 and dsDNA titres improved significantly (both p=0.04). Non statistically significant numerical improvements were seen in C4 levels.

Of 8/9 patients receiving concomitant oral prednisolone at baseline (all >10mg/day), 5/9 had their dose reduced at 6 months; 4/8 were on 5mg/day and were in Lupus Low Disease Activity State. After obinutuzumab, 6/9 patients with peripheral B-cell data achieved complete depletion including 4/4 assessed with highly sensitive assays. 1/9 obinutuzumab non-responder required cyclophosphamide therapy. 1 unvaccinated patient died from COVID-19.

Table 1.

Baseline characteristics, disease activity and steroid doses before and after last obinutuzumab/rituximab.

PatientEthnicityDisease duration (Years)Age (Years)Total BILAG-2004 before ObiTotal BILAG-2004 after ObiSLEDAI-2K before ObiSLEDAI-2K after ObiPrednisolone before Obi (mg)Prednisolone after Obi (mg)1South Asian10.836.41821481052South Asian6.324.424212430103South Asian11.934.829110410104South Asian8.241.92116015155South Asian6.829.43221181450606White European17.537.0128881557White European16.930.01211281058Caribbean6.244.225213010159Caribbean2.621.092166105Median (Q1, Q3)NA8.2 (6, 12)34.8 (29,37)21 (12, 25)2 (1, 2)12 (10, 14)6 (4, 8)10 (10, 15)10 (5, 15)

Conclusion

Obinutuzumab appears to be effective and steroid-sparing in renal and non-renal SLE patients with secondary non-response to rituximab. Obinutuzumab was shown to be effective in patients with severe renal and non-renal disease. Therefore, in those with previous responsiveness to B-cell depletion, switching to humanised type-2 anti-CD20 therapy is a logical approach following loss off efficacy.

References

[1]Vital EM, Dass S, Buch MH, Henshaw K, Pease CT, Martin MF, et al. B cell biomarkers of rituximab responses in systemic lupus erythematosus. Arthritis Rheum [Internet]. 2011 Oct [cited 2020 Oct 12];63(10):3038–47. Available from: https://pubmed.ncbi.nlm.nih.gov/21618204/

[2]Hassan SU, Md Yusof MY, Emery P, Dass S, Vital EM. Biologic Sequencing in Systemic Lupus Erythematosus: After Secondary Non-response to Rituximab, Switching to Humanised Anti-CD20 Agent Is More Effective Than Belimumab. Front Med [Internet]. 2020 Aug 27 [cited 2020 Sep 2];7:498. Available from: https://www.frontiersin.org/article/10.3389/fmed.2020.00498/full

Disclosure of Interests

Jack Arnold: None declared, Shouvik Dass Consultant of: Roche, Abbvie, UCB & Chugai, Employee of: Honoraria from Roche, Abbvie, UCB & Chugai, Sarah Twigg: None declared, Colin Jones: None declared, Benjamin Rhodes: None declared, Peter Hewins: None declared, Mithun Chakravorty: None declared, Philip Courtney: None declared, Michael Ehrenstein Grant/research support from: GSK, Employee of: Has received honoraria from GSK, Md Yuzaiful Md Yusof: None declared, Edward Vital Employee of: Has received honoraria from Roche

POS1412 IDENTIFYING HIGH-COST DRUGS FOR RARE RHEUMATIC DISEASES IN ROUTINELY COLLECTED NHS DATA. RESULTS FROM A PILOT STUDY OF RITUXIMAB USE IN VASCULITIS USING DATA FROM THE NATIONAL DISEASE REGISTRATION SERVICE AND THE REGISTRATION OF COMPLEX RARE DISEASES-EXEMPLARS IN RHEUMATOLOGY (RECORDER) PROJECT

Background:

Understanding real-world usage of high-cost drugs is crucial to support planning, adoption of innovation and reduce unwarranted variation in treatment. Hospital Episode Statistics (HES) contain diagnoses (coded by ICD-10) and procedures/treatments (coded by OPCS) for all daycase or inpatient care in England. However, OPCS codes are not specific for individual drugs, for example X921 (cytokine inhibitors band 1) includes rituximab (RTX) and 15 other drugs.

Objectives:

We aimed to validate the accurate identification of patients treated with RTX for ANCA-associated vasculitis (AAV) using HES data.

Methods:

We used data from the National Congenital Anomaly and Rare Disease Registration Service (NCARDRS) at Public Health England and their legal permissions (CAG 10-02(d)/2015). We extracted records from HES of all patients treated at two hospitals during financial year 2018/19 who ever had a coded diagnosis of granulomatosis with polyangiitis (GPA, M313), eosinophilic granulomatosis with polyangiitis (EGPA, M301), microscopic polyangiitis (MPA, M317), polyarteritis nodosa (PAN, M300) or arteritis unspecified (I776). Where people had multiple diagnoses of vasculitis, the most specific was considered their diagnosis. Enabled by data sharing agreements, we reviewed hospital records of those patients to validate diagnoses and whether X921 reliably identified RTX. We report the positive predictive value and sensitivity of the coding for X921 and GPA/EGPA/MPA for identifying people with AAV who are treated with RTX.

Results:

At Trust 1 records ever coded with GPA/EGPA/MPA identified 74 people, 69 of whom had AAV confirmed in their medical notes. Among these 74 patients there were 59 episodes coded with X921 procedure codes, of which 56 correctly identified a RTX infusion given for AAV. A total of 64 RTX infusions were given to people with AAV – 3 missed infusions were X921 procedures in patients who had coded diagnoses of PAN or I776 but never GPA/EGPA/MPA and 5 infusions were not coded as X921.

The same analysis at Trust 2 identified 46 people, 44 of whom had AAV confirmed in their medical notes. Among patients identified with AAV there were 17 episodes coded as X921, of which 15 correctly identified a RTX infusion. A total of 23 infusions were given to people with AAV: 4 infusions were X921 procedures in patients who had coded diagnoses of PAN or I776 but never GPA/EGPA/MPA, and 4 infusions were not coded as X921.

Table 1.

Summary of Positive Predictive Values (PPV) applying our algorithm to identify AAV diagnoses and RTX use

Trust 1Trust 2CombinedDiagnosis of AAV and coded as AAV6944113AAV coded7446120Diagnosis of AAV under any code7355128PPV AAV ascertainment (95% CI)93.2% (84.9-97.8)95.7% (85.2-99.5)94.2% (88.4-97.6)Sensitivity of AAV ascertainment (95% CI)94.5% (86.8-98.5)80.0% (67.0-89.6)88.3% (81.4-93.3)RTX given in people coded as AAV561571RTX coded in people coded as AAV591776RTX given for AAV under any diagnostic or procedure code642387PPV RTX ascertainment (95% CI)94.9% (85.9-98.9)88.2% (63.6-98.5)93.4% (85.3-97.8)Sensitivity of RTX ascertainment (95% CI)87.5% (76.8-94.4)65.2% (42.7-83.6)81.6% (71.9-89.1)

Conclusion:

HES data identified patients treated with RTX for AAV with a PPV of 93.4% (85.3-97.8) and sensitivity of 81.6% (71.9-89.1). This demonstrates the utility of national data to identify people receiving RTX for AAV. The RECORDER project, within the National Disease Registration Service plans to conduct real-world studies of the high-cost drug RTX, given for AAV, across the whole of England, and assess whether geography, demographics or socioeconomic factors influence frequency of prescription of this, and potentially other, high-cost drugs in line with the NHS long term plan.

References:

[1]Ward-Platt M, Stevens S, Miller N. I18 The national congenital anomaly and rare disease registration service (NCARDRS): The first year

Acknowledgements:

I have no acknowledgements to declare.

Disclosure of Interests:

Cattleya Godsave: None declared, Mithun Chakravorty: None declared, Megan Rutter: None declared, Peter Lanyon Grant/research support from: P.C.L. is a recipients of a grant from Vifor Pharma. Vifor Pharma had no influence on the design, conduct or interpretation of this study., Jeanette Aston: None declared, Mary Bythell: None declared, Sarah Stevens: None declared, Fiona Pearce Grant/research support from: I have received a research grant from Vifor Pharma

28 Medication Compliance Aids and Acute Hospitals

Introduction

An estimated 64 million Medication Compliance Aids (MCAs) are dispensed by pharmacies in England each year as a method of reasonable adjustment to improve medication adherence (NICE 2009) and support medicines administration by carers (RPS 2013). Complexities exist when implementing medication changes for patients using MCAs, particularly at hospital discharge or outpatient appointments, where practices seem to vary. This National Survey is the first to determine the current policy and service provision of MCAs by acute hospitals in England.

Methods

An electronic survey was emailed to Chief Pharmacists via the Regional Medicines Information Services in Spring 2019. Initial non-responders were contacted by email and telephone.

Results

51% (73/144) of acute hospital trusts in England responded. 77% (56/73) dispensed medication in MCAs at discharge. Of these, 62.5% would initiate MCAs and 61% supplied a different length of MCA vs non-MCA prescription (see table).

41 hospitals had designated staff completing MCAs. The median time to complete an MCA was 59.5 minutes (range 10–200). The median time from prescription receipt in pharmacy to MCA arrival on ward was 144.5 minutes (range 60–1,440).

Of the 17 hospitals not providing MCAs, the majority would, upon discharge, contact the community pharmacy that provided the MCA pre-admission to update any medication changes and request the provision of a new supply of medicines.

Conclusion

Despite the ubiquitous nature of the MCA, there is no standard approach to the supply of these devices from acute hospitals across England. When hospitals do provide MCAs their preparation is time consuming, often requiring additional staff. A national approach to MCAs might help patients and carers, and reduce medication-related problems and costs.

1 Quality of Care Transitions: Older Adults’ Experiences in An Integrated Care Trust

Introduction

The transition of care from hospital to home is a high-risk time for older adults. The Partners at Care Transitions (PACT) programme aims to improve safety and quality of care transitions. We aimed to test the feasibility of using the Partners at Care Transitions Measure (PACT-M) to evaluate older adults’ experiences of the transition from hospital to home in an Inner London Integrated Care Trust and to identify factors impacting transition quality.

Methods

The PACT-M, a validated patient-reported questionnaire designed to evaluate care transitions, was administered to patients ≥65 years at 7, 30 and 90 days post-discharge. Likert scores were analysed quantitatively and manual thematic analysis performed on free-text comments.

Results

101 participants were recruited. Mean age 77.8 years. 84, 70 and 65 participants completed follow-up at 7, 30 and 90 days, respectively.

Factors impacting patients’ experience of transition quality are shown in Table 1.

Conclusions

130 Improving Documentation of Bowel Movement on Geriatric Wards

Introduction

Constipation is a widely prevalent issue in older adults that may result in complications such as urinary retention, delirium and bowel obstruction. Previous studies have indicated that while stool charts are well completed by nursing staff, they are infrequently monitored by doctors. This project aimed to improve the documentation of bowel movement by doctors on ward rounds to 85%, by the end of a 3-month period.

Methods

Formulation of the project was achieved using group work and a fishbone diagram which focussed on how doctors can improve on documenting bowel movements. Baseline data were collected from inpatient notes on weekdays over a three-week period on a geriatric ward in Northern General Hospital, Sheffield. Interventions of posters and stickers of the poo emoji were placed on walls and in inpatient notes respectively as a reminder. Post-intervention data were collected on weekdays over two weeks, and then repeated a month later to assess for a sustained change.

Results

The data on bowel activity documentation were collected from 28 patients. The baseline data showed that bowel activity was monitored daily on the ward 56.25% of the time. There was a significant increase in documentation of 85.75% following the interventions. The sustainability study showed that bowel activity was documented on the ward 59.09% of the time.

Conclusions

This study shows how a strong effect on behavioural change can be accomplished through simple interventions such as stickers and posters. As most wards currently still use paper notes, this is a generalisable model that other wards can trial. However, this study also shows the difficulty in maintaining behavioural change over extended periods of time. Further PDSA cycles should examine the reasons behind the difficulty sustaining the change and implement new changes that aim to overcome them.

SAT0483 SAFETY OF INTRAVENOUS IBANDRONIC ACID IN CHRONIC KIDNEY DISEASE: A REAL WORLD EXPERIENCE

Background:

Common forms of intravenous bisphosphonate used at the Royal Derby Hospital are zoledronic acid and ibandronic acid for a variety of indications. In the treatment of osteoporosis, zoledronic acid is preferred due to its convenience of once-yearly dosing; compared to ibandronic acid which is given three-monthly. Zoledronic acid is contraindicated in patients with an estimated glomerular filtration rate (eGFR) of less than 35 due to nephrotoxicity concerns. Ibandronic acid, however, is generally offered with an eGFR of 30 or over and is perceived to be a safer choice in more advanced chronic kidney disease. The potential of extending the use of ibandronic acid to patients with lower eGFR is being explored. However, there is a paucity of real world data and this study will therefore seek to affirm the safety profile in those on treatment.

Objectives:

Establish the safety profile of IV ibandronic acid with regards to worsening renal function or significant hypocalcaemia injury in the context of reduced renal clearance.

Methods:

The details of patients receiving IV ibandronic acid at Royal Derby Hospital were retrieved from the osteoporosis department register in September 2019. Data was collected anonymously from records using the electronic prescribing and pathology hospital database, together with electronic letters. The first three pre-infusion serum adjusted calcium levels, vitamin D, creatinine and eGFR were recorded. In addition, results from initiation to present were screened for any episodes of hypocalcaemia, acute kidney injury (AKI) or significant decline in renal function.

Results:

Treatment duration ranged from 6 months to 6 years. Female:male ratio was 9:1 and the average age was 75 years (range 50-90). Baseline eGFR ranged from 27 to over 60; 3 patients had eGFR≥60, 2 had eGFR 27 while remaining patients (75%) had eGFR 30-59. All patients received a standard 3mg infusion on each occasion. The most common rationale cited for ibandronic acid choice as opposed to zoledonic acid was reduced creatinine clearance or eGFR. Three patients (15%) developed one or more episodes of mild hypocalcaemia (lowest 2.01 mmol/l). No episodes of hypocalcaemia were identified in the first three pre-infusion levels. Four patients (25%) had a decline in eGFR by more than 5 ml/min/1.73m2but there was no definitive causal link with ibandronic acid and was most commonly felt to be related to their underlying renal disease. Three patients (15%) had at least one episode of AKI since commencing treatment, each explained by an intercurrent illness. Serum Vitamin D levels were measured pre-infusion in 92% of cases.

Conclusion:

This study reaffirms the safety profile of ibandronic acid use in renal function as low as CKD Stage 3b (≥30ml/min/1.73m2). No episodes of AKI or sustained decline in renal function were causally linked to ibandronic acid.

References:

Royal Derby Hospital Proposed Clinical Guideline (2019) – Use of ibandronic acid in CKD 4 at reduced dosage.

Disclosure of Interests:

None declared

AB1342-HPR RHEUMATOLOGY ‘HOT CLINIC’ IN A TEACHING HOSPITAL - WHAT CAN BE EXPECTED?

Background:

Increased financial and bed pressures faced by the NHS have necessitated significant changes in the service provision of many inpatient medical specialties. At the Royal Derby Hospital, rheumatology has become predominantly outpatient-based and no longer has an allocated ward for inpatients. As a result, weekly rheumatology ‘hot clinic’ have been set up to help facilitate early hospital discharge and specialist outpatient review of patients with suspected rheumatological conditions. It was anticipated that the bulk of referrals would be for conditions requiring early intervention such as suspected giant cell arteritis (GCA) and hot swollen joints. However, there is a paucity of literature on the usefulness of such ‘hot clinics’ and the quality of referrals.

Objectives:

This study sought to evaluate the range of conditions referred to the ‘hot clinic’ and early outcomes related to follow up or discharge.

Methods:

The details of patients who attended the ‘hot clinic’ were retrospectively obtained using the hospital’s electronic clinic appointments system. Electronic letters and discharge summaries were reviewed to determine the patient’s presenting symptoms, suspected diagnosis and clinical outcome.

Results:

A total of 40 patients who attended the ‘hot clinic’ from September 2018 to June 2019 were included. The average time from discharge to ‘hot clinic’ was 3.8 days (range 0-22 days). 27 patients (67.5%) were seen within 7 days of hospital discharge and 2 patients were seen after 18 and 22 days respectively, which spanned over the Christmas and New Year period.

87.5% (35) of patients were referred by acute medicine via the ambulatory care ward; 10% (4) by the Emergency Department and 1 by the medical ward. 5 patients were already known to rheumatology (3 with rheumatoid arthritis and 2 with psoriatic arthritis).

37.5% of referrals were made for suspected GCA, 35% for rash and possible connective tissue disease (CTD) or vasculitis except for GCA, 20% for swollen joints, and 7.5% for unexplained arthralgia or myalgia.

For the patients with suspected GCA, 3 out of 15 were treated as GCA after ‘hot clinic’ review - 2 of these went on to have a temporal artery biopsy and 1 had a positive biopsy for GCA. (All 3 received high dose steroids prior to their clinic appointment). 10 patients were felt to have an atypical headache and 3 of these were referred to neurology for further assessment. The remaining 2 patients were diagnosed with a sinus infection and migraine respectively.

Of the 14 patients referred with a rash and possible CTD or vasculitis except for GCA, 2 patients referred with a rash were diagnosed to have IgA vasculitis and referred to dermatology for further management. 2 patients were diagnosed with lupus and were followed up in the CTD clinic. 7 patients were felt to have a self-limiting post-viral or non-specific rash, 2 patients with possible drug-related rash and 1 patient thought to have erythema nodosum.

2 patients with swollen joints had a new diagnosis of seronegative inflammatory arthritis and 2 others were diagnosed with gout. 1 patient was diagnosed with osteoarthritis and another with post-viral arthritis and both were discharged.

The 3 patients with unexplained arthralgia or myalgia were felt to have self-limiting post-viral illnesses and were also discharged.

Conclusion:

Suspected GCA is the most common referral to the rheumatology ‘hot clinic’. However, the vast majority of these referrals turned out not to be GCA. The results of this study clearly suggest the need for development of better pathways e.g. for GCA and joint dermatology and rheumatology clinics.

Disclosure of Interests:

None declared

P.C. Sen Memorial best paper award on rural health practice: A study on visual acuity and vitamin A deficiency among primary school students in Naxalbari Village, Darjeeling district of West Bengal

331 primary school students studying from Nursery classes to Class IV in 2 randomly selected schools in Naxalbari Village in Darjeeling district of West Bengal were tested for visual acuity (VA), Vitamin A deficiency (VAD) and Bitot's spot. 329 students could be tested for visual acuity whereas all 331 students were tested for VAD and Bitot's spot. The prevalence of abnormal Visual Acuity (VA) (VA < 6/9 in any eye) in this study group was 3.65% and it was highest in 7-8 years age group in both the sexes contributing to 75% of the total students having abnormal VA. All these children fell within 50th percentile of weight and height for their respective age and sex. Hindu & ST children accounted for 91.67% & 50% abnormal VA respectively; however, when presence of abnormal VA was compared with its absence between 2 sexes, Hindu and Muslim students and in different castes, no statistically significant differences were found (p > .05). Students of Class-I and Class-II contributed 25% and 50% respectively and together accounted for 75% of abnormal VA. Prevalence of VAD was 8.16%. Among sufferers of VAD Hindus (81.48%) and ST (51.85%) were the main contributors; the differences between presence and absence of VAD in 2 sexes, among 3 religious groups were not statistically significant (p > .05); however, differences among ST and NonSCST groups, and again SC, ST and Non-SCST groups were statistically significant (p < .05). Prevalence of Bitot's spot was 3.63%. Among the students having Bitot's spot, females (58.33%) outnumber the males (41.67%); but the difference between presence and absence of Bitot's spot in 2 sexes was not statistically significant (p > .05). 83.33% each of Hindus and STs had Bitot's spot. No SC and no Muslim student had this spot; the differences between presence and absence of Bitot's spot between Hindu and Christian students were statistically significant (p < .01); similarly when the findings were considered between ST and NonSCST students the difference was found to be statistically highly significant (p < .001).

Multiple copies of the upstream regulatory region of the major capsid protein gene of bacteriophage MB78 inhibit phage morphogenesis

The 2.311 kb EcoRI F fragment of bacteriophage MB78 has been cloned in multicopy vectors pUC19 and pCR90. Salmonella typhimurium strains carrying such plasmids cannot support development of phage MB78 while other Salmonella phages like P22 and 9NA grow normally. Most of the phage MB78 induced functions are normal in such transformed hosts but proper maturation of the phage particles does not take place. Deletion of 138 bp from the 3' end of the cloned fragment reverses the inhibitory effect. Analysis of nucleotide and the deduced amino acid sequence of a 1.2 kb HindIII-SalI fragment of the phage genome which overlaps the 138 bp confirms that this part contains the upstream regulatory region of the major structural protein gene. It seems that in presence of multiple copies of the upstream regulatory region (which includes a number of promoter like sequence) of the coat protein gene, the maturase gene is down regulated and this is effective only in cis, a situation quite similar to that of Qbeta RNA phages.

Cloning, sequencing, expression and promoter analysis of a structural protein of bacteriophage MB78

Bacteriophage MB78, a virulent phage of Salmonella typhimurium isolated in our laboratory. It is different from the well-known temperate phage P22 and 9NA. A detailed physical map has been constructed. To understand more about the physiology and genetics of this interesting phage it has become necessary to fragment the phage genome, clone the fragments and analyze in depth. A number of promoters of bacteriophage MB78 have been cloned and characterized recently. As a part of this program, in this investigation, we report cloning, sequencing and expression and promoter analysis of the ClaI G fragment. We identified the expressed protein as phage structural. Phage structural proteins play a vital role in forming the core head of the phage particle.

Synthesis of a bacteriophage MB78 late protein by novel ribosomal frameshifting

MB78 is a virulent phage of Salmonella typhimurium that possesses a number of interesting features, making it a suitable organism to study the regulation of gene expression. A detailed physical map of this phage genome has been constructed and is being extensively studied at the molecular level. Here, we demonstrate the expression of two late proteins of bacteriophage MB78 derived from the same gene as a result of possible ribosomal frameshifting. In vitro transcription-translation yields a major protein that migrates as 28kDa, whereas in vivo expression using pET expression vectors yields two equally expressed proteins of molecular sizes 28 and 26kDa. A putative slippery sequence TTTAAAG and a pseudoknot structure, two essential cis elements required for the classical ribosomal frameshifting, are identified in the reading frame. Mutations created at the slippery sequence resulted in a single 28kDa protein and completely abolished the expression of 26kDa protein. Thus, we have produced the first evidence that ribosomal frameshifting occurs in bacteriophage MB78 of Salmonella typhimurium.

Expression of four genes of bacteriophage MB78 from contiguous open reading frames: the genomic organization as deduced by sequence analysis

Four proteins of bacteriophage MB78 having apparent molecular weights as 35, 14, 21 and 16 kDa are expressed from 3.9 kb SalI-HindIII fragment located almost in the middle of the phage genome. Analysis of the sequence supported by some experimental evidences suggest that these four proteins are expressed from polycistronic message without any intercistronic gap. Stop and start codons of consecutive ORFs overlap and rare initiation codons are used. Computer analysis of the sequence suggests the presence of two more open reading frames within the ORFs of 35 and 16 kDa proteins but in the opposite orientation, i.e. in the complementary strand.

Molecular cloning, sequencing, and expression of two late proteins of bacteriophage MB78

Bacteriophage MB78, a virulent phage of Salmonella typhimurium, does not allow other phages, such as P22 and 9NA, to grow in its presence. A detailed physical map of this phage has been constructed in our laboratory. In an ongoing effort to understand the genetics of this interesting phage, various genes were characterized. Here, we report cloning, sequencing, and expression of two late proteins, coded in a SalI-HindIII fragment (SH9), by using the minicell expression system. Further, we performed a kinetic study of phage proteins by infection the host LT2 cells and compared the proteins produced, with proteins obtained by the minicell expression system. Both sets of proteins run exactly parallel and migrated as 14- and 15-kDa proteins on a polyacrylamide gel. The synthesis of these two proteins started 15 min after infection with MB78 and was prominent after 45 min. One of the proteins exhibited 57% homology to the structural protein of mycobacteriophage L5.

Identification of a strong promoter of bacteriophage MB78 that lacks consensus sequence around minus 35 region and interacts with phage specific factor

A strong promoter of bacteriophage MB78 does not have minus 35 consensus sequence although it has a TGn motif immediately upstream of minus 10 sequence as well as the AT rich UP element. It is efficiently recognised by the sigma 70 RNA polymerase, however, a phage-specific factor competes with sigma 70 RNA polymerase for binding to this region, the binding of the factor being stronger than that of the polymerase. Contrary to the reports in the literature the polymerase appears not to bind to the UP element whereas the phage-specific factor does. The latter seems to be involved in the regulation of the promoter activity.

A supercoil-specific endonuclease from Salmonella typhimurium cleaves both negatively and positively supercoiled DNA

An enzyme which specifically cleaves supercoiled DNA to linear form through nicked circular form as intermediate was isolated from rifampicin-resistant mutant of Salmonella typhimurium, rif 39. The enzyme activity was stimulated by Mg+2, whereas Ca+2 had no effect. It does not require ATP for its activity. No activity could be detected with relaxed or single stranded circular DNAs. The molecular weight of the enzyme is approximately 34 kDa. The most characteristic feature of this enzyme is that it cleaves both positively and negatively supercoiled DNAs.

Exclusion of temperature bacteriophage P22 by virulent bacteriophage MB78 of Salmonella typhimurium: competition for association with the replication complex

MB78, a virulent bacteriophage of S. typhimurium does not allow other bacteriophages like P22 and 9NA to multiply in its presence. The exclusion of P22 by MB78 is found to be due to competition for common binding site(s) in the host cell membrane. As a result, P22 DNA fails to replicate in presence of MB78 DNA. Further, the sedimentation profile of P22 DNA in cells infected simultaneously with P22 and MB78 suggested fragmentation of P22 DNA. This may also contribute to the exclusion phenomenon.

Construction of a cloning vector from a naturally occurring plasmid of Salmonella typhimurium

A naturally occurring plasmid isolated from a drug-resistant strain of Salmonella typhimurium (993) has been used to construct a plasmid vector for cloning in a wild strain of Salmonella. The strain (993) contains at least two plasmids. The smaller plasmid (9 kb) contains an ampicillin-resistant marker, while the larger one (25 kb) is cryptic. Physical mapping of the 9-kb plasmid and construction of a 3.5-kb derivative have been carried out. This plasmid has been used for cloning in a restriction+modification+strain of S. typhimurium using a conventional calcium chloride method. It exhibited better efficiency of transformation than other commonly used plasmids such as pBR322 or its derivatives and transformants were found to be stable in the absence of antibiotic selection. The vector is compatible with pBR322 and can be used to study the expression of cloned genes in minicells.

Abortive infection of the virulent phage 9NA in a fatty acid auxotroph of Salmonella typhimurium: effect of fatty acid supplementation

A conditional (temperature sensitive) fatty acid biosynthetic mutant (fabB2) of Salmonella typhimurium does not support the development of the virulent bacteriophage 9NA even at permissive temperature (30 degrees C). A limited amount of phage DNA synthesis takes place at this temperature. When the fatty acid composition of the host membrane is altered by growing the cells at 37 degrees C in the presence of exogenous unsaturated fatty acid, differential expression of phage genes was observed. Phage specific lysozyme is induced when the cultures are supplemented with elaidic, palmitelaidic, linoleic and linolelaidic acids but not with oleic and plamitoleic acids. However, in no case were infective particles produced. Under conditions where no lysozyme is synthesized the infected cells increase in length and become filamentous.

Spontaneous deletions of drug-resistance determinants from Salmonella typhimurium in Escherichia coli

Plasmids isolated from two different clinical isolates of Salmonella typhimurium, both resistant to the antibiotics ampicillin, tetracycline, streptomycin and chloramphenicol, were used to transform Escherichia coli. Segregation of antibiotic-resistance determinants occurred in both cases. Analysis of plasmids from one set of segregants by DNA-DNA hybridisation indicated that the segregation was due to precise deletions in the transforming plasmid.

Isolation of temperature-sensitive mutants of bacteriophage MB78 and correlation between the physical and genetic maps

In order to study the biochemistry and genetics of the virulent virus MB78 of Salmonella typhimurium, 31 temperature-sensitive mutants of the phage were isolated following mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. These have been classified into six complementation groups (A through F). Linkage between different complementation groups has been mapped by using two factor crosses between representative members of each group. To correlate the physical and genetic maps of the phage, complementation between bacterial clones carrying plasmids with EcoRI fragments of the phage DNA as inserts and the ts mutants was studied. Good correlation between the physical and genetic maps has been obtained. Tentative locations of the ts mutations on the phage genome have thus been determined.

Hybrid between temperate phage P22 and virulent phage MB78

Bacteriophage MB78, a virulent phage of Salmonella typhimurium can not grow in rifampicin resistant mutant of the host. However, the temperate phage P22 which grows normally in this host helps MB78 to grow in its non-permissive host. P22 can not itself multiply under the condition of mixed infection and the burst size of MB78 is very much reduced. The burst sizes of both are reduced even when the permissive host LT2 is mixedly infected with P22 and MB78. When rifampicin resistant mutants are mixedly infected, only P22-specific mRNAs are produced in the early stage. This is followed by transcriptions from both P22 and MB78 genomes. Subsequently, only MB78-specific messengers are detected in the infected host. Hybrids between the two phages have been isolated from the mixedly infected cells. These hybrids which contain only 15-20% of P22 genome can grow in the rifampicin resistant mutants of the host. The analysis of hetero-duplex between MB78 and hybrid phages revealed the presence of at least three mismatch regions. Experiments are in progress to identify the parts of P22 genome present in the hybrid phage.

Bacteriophage P22 helps bacteriophage MB78 to overcome the transcription inhibition in rifampicin resistant mutant of Salmonella typhimurium

Bacteriophage MB78 cannot grow on rifampicin resistant mutant of host Salmonella typhimurium (rif39) which contains an altered beta subunit of RNA polymerase. Bacteriophage P22, however, grows normally in rif39 both in the presence or absence of rifampicin. Perhaps MB78 promoter is not recognized by altered RNA polymerase. As the phage P22 helps MB78 to grow to some extent on rif39, hybrids between P22 and MB78 have been isolated. Hybrid phage which can grow on rif39 contains mostly genes from MB78 although a small portion (15-20 per cent) of the genome belongs to P22 genome which helps MB78 to overcome the transcription inhibition in the host mutant with altered RNA polymerase.

Thiolutin-resistant mutants of Salmonella typhimurium

Spontaneous mutants of Salmonella typhimurium isolated in our laboratory from thiolutin-containing tryptone agar plates are partially resistant to thiolutin in enriched media. In minimal media, they are not resistant. The mutants are not temperature sensitive but fail to support the development of phage P22 at higher temperatures (40 degrees C). Thiolutin did not interfere with RNA polymerase or nucleotide kinase in in vitro experiments. However, thiolutin did inhibit the rate of incorporation of exogenous uridine into the cellular pool and consequently the acid-precipitable material. It appears that one site of action of thiolutin is at the membrane level.

Participation of the host protein(s) in the morphogenesis of bacteriophage P22

Spontaneous mutants of S. typhimurium resistant to thiolutin are conditionally non-permissive for phage P22 development (Joshi and Chakravorty 1979). At 40 degree C non-infective phage particles are produced. Phage development in two nonpermissive hosts (18/MC4 and 153/MC4) has been studied in detail. The steps at which the phage morphogenesis is interfered with differ in the two mutants. The electron micrograph of the particles produced in the mutant 18/MC4 reveals the presence of normal-looking particles; these particles contain phage DNA, adsorb to the permissive host but fail to inject their DNA. The particles produced in the mutant 153/MC4 which fail to adsorb to the host are found to be tail fibre-less. These observations indicate the involvement of host protein(s) in phage P22 morphogenesis.

MB78, a virulent bacteriophage of Salmonella typhimurium

The isolation and some properties of a virulent bacteriophage of Salmonella typhimurium, MB78, which is morphologically, serologically, and physiologically unrelated to P22, are reported. The phage has a noncontractile long tail with partite ends. It cannot multiply in minimal medium in the presence of citrate. MB78-infected cells are, however, killed in such medium. This phage cannot grow in rifampin-resistant mutants of the host. The latent period of growth of this phage is much shorter than that of P22. Both sieA and sieB genes of the resident P22 prophage are required to exclude the superinfecting MB78 phage, whereas all temperate phages related to P22 are excluded by either one or both of the genes individually. Restriction endonuclease cleavage patterns of P22 and MB78 are distinctly different. The absence of homology between the two phages P22 and MB78 suggests that MB78 is not related to phage P22.

Is the injection of DNA enough to cause bacteriophage P22-induced changes in the cellular transport process of Salmonella typhimurium?

It was demonstrated earlier in this laboratory that phage P22 induces a transient depression in the cellular transport processes of the host Salmonella typhimurium immediately after infection and that an effective injection process is enough to cause the depression. By using defective phage particles that contain host DNA instead of phage DNA for infection, it has been demonstrated that the injection of phage-specific DNA is essential for this. The defective particles adsorbed to the host and injected their DNA, but the cellular transport processes of the host were not altered. Thus, the injection of host DNA by the phage fails to affect the transport process. Insensitivity of the phage DNA-induced depression in transport to chloramphenicol rules out the involvement of newly synthesized protein in this change and indirectly suggests the possible role of phage DNA-associated internal proteins of P22.

Effect of spermidine on bacteriophage P22 infection

The effect of spermidine on phage P22 infection of Salmonella typhimurium has been found to depend on the time of addition of spermidine with respect to the time of addition of the phage and also on the composition of the growth medium. If spermidine was added prior to or within a short time after infection, the cells survived. Under this condition the invading DNA appeared to remain trapped in the cell membrane, and there was no expression of the phage genome. If spermidine was added after the initiation of the infective process, the replication of the phage was inhibited but the cells did not survive. If spermidine was added after DNA synthesis was over, there was no effect of spermidine on phage multiplication. Spermidine was found to affect phage DNA synthesis but not host DNA synthesis.

Superinfection exclusion and changes in cellular transport processes in phage infected Salmonella typhimurium

The changes induced by bacteriophage P22 in the cellular transport process(es) of the host Salmonella typhimurium (Taneja et al., 1975; Khandekar et al., 1975; Bandyopadhyay and Chakravorty, 1976) involve interactions between the superinfection exclusion system of the resident prophage and the C immunity region of the superinfecting phage. The sie A gene of the prophage interferes with the changes in the cellular transport process induced by the superinfecting phage. However, if the superinfecting phage carries active C1 and C2 genes there is no such interference. Thus the C1 and C2 genes of the superinfecting phage seem to be expressed in the sieA+ lysogen.

Effect of m3 gene on the development of phage P22

Mutation of the gene m3 of phage P22 causes permanent depression of macromolecular synthesis in the infected host and thus inhibits phage development as indicated by burst size and lysozyme production. The permanent depression of macromolecular synthesis is most probably due to blockage of the transport process. The m3 allele is dominant over m+. m3 allows some transcription of phage genes (however, the difference between early and late function is not clear). The inhibitory effect of m3 on DNA synthesis may be indirect.

Transport in bacteriophage P22-infected Salmonella typhimurium

There was rapid efflux of L-leucine, L-phenylalanine, and alpha-methyl-D-glucoside after infection of Salmonella typhimurium with the clear plaque mutant C1 of phage P22. The efflux was similar to that observed with cyanide or arsenate treatment except that there was partial recovery in the case of phage infection and almost complete recovery under the condition of lysogeny. There was no efflux after infection with the temperature-sensitive mutant ts16C1 at nonpermissive temperature. Superinfection of superinfection exclusion negative lysogen (sie A minus sie B minus) with C1 led to efflux, whereas the efflux was much less on superinfection of sie A+ Sie B+ lysogen. These results indicate that an effective injection process is enough to cause depression in the cellular transport processes.

Induction and repression of L-arabinose isomerase in Salmonella typhimurium

As with other inducible enzymes, the induced synthesis of l-arabinose isomerase (l-arabinose ketol isomerase, EC 5.3.1.4) in Salmonella typhimurium is subject to catabolite repression. Of the three catabolite repressors tested, glucose produces maximum repression. Analogues of catabolite repressors like 2-deoxy-d-glucose and d-fucose also inhibit the synthesis of the enzyme. The catabolite repression is completely reversed in the presence of 1.5 x 10(-3)m cyclic 3',5'-adenosine monophosphate (AMP). The maximum repression is produced in glucose-grown cells in glucose-containing induction medium. Cyclic 3',5-AMP reverses this repression provided that the cells are treated with ethylenediaminetetraacetic acid (EDTA). In normal cells, cyclic 3',5'-AMP has no effect on the induction but in EDTA-treated cells the cyclic nucleotide enhances synthesis of the enzyme. The inhibition produced by d-fucose cannot be reversed by cyclic 3',5'-AMP. d-Fucose competes with the inducer l-arabinose in some step(s) involved in the process of induction.

Control of the replication complex of bacteriophage P22

A replication complex for the vegetative synthesis of the deoxyribonucleic acid (DNA) of the temperate phage P22 previously has been described. This complex is an association of parental phage DNA, most of the newly synthesized phage DNA made during pulses with (3)H-thymidine, and other cell constituents, and has a sedimentation rate in neutral sucrose gradients of at least 1,000S. The complex is one of the intermediates, intermediate I, in the synthesis and maturation of phage P22 DNA after infection or induction. Evidence supporting the replicative nature of intermediate I is presented. Phage replication is repressed in lysogenic bacteria. On superinfection of P22 lysogens with nonvirulent phage, little association of the input phage DNA with a rapidly sedimenting fraction is demonstrable. However, after induction with ultraviolet light, the superinfecting parental phage DNA quickly acquires the rapid sedimentation rate characteristic of intermediate I; phage DNA synthesis follows; and progeny phages are produced. Infection with a virulent mutant of P22 produces progeny phages in lysogens. Its DNA associates with intermediate I. In mixed infection with the virulent phage, replication of nonvirulent phage P22 is still repressed, even though the virulent replicates normally. The nonvirulent input DNA does not associate with intermediate I. The repressor of the lysogenic cell prevents replication by interfering with the physical association of template material with intermediate I. A phage function is required for association of phage template with the replication machinery.

Induction and repression of L-arabinose isomerase in bacteriophage-infected Salmonella typhimurium

The induction of l-arabinose isomerase in Salmonella typhimurium (LT2) is repressed on infection with clear plaque forming mutants (C(1) and C(2)) of the temperate phage P22 (C(+)). However, after infection with C(+) leading to lysogeny, there is a temporary repression. During this period, messenger ribonucleic acid (RNA) for l-arabinose isomerase accumulates. DNA-RNA hybridization data suggest that there is transcription of host DNA during the period of repression. Interference at the level of translation might be responsible for the cessation of induced enzyme synthesis.

Absence of immunity to superinfection in spheroplasts of a lysogen

Penicillin-induced spheroplasts of Salmonella typhimurium strain LT2 lysogenic for bacteriophage P22, appear to lose immunity to superinfection by homologous phage.