Intraoral Gavage of Second-Generation Probiotic Lactobacillus Reuteri Releasing IFN-β (LR-IFN-β) Mitigates Intestinal Irradiation Toxicity and Improves Survival During Whole Abdomen Irradiation (WAI)

PURPOSE/OBJECTIVE(S)

We sought to establish a method by which to overcome the toxicity of WAI to facilitate clinical application in Ovarian Cancer patients.

MATERIALS/METHODS

We irradiated C57BL/6J mice to 19.75 Gy WAI and assessed the primary endpoint of overall survival (OS). In a separate experiment, mice were irradiated to 12 Gy WAI and intestinal barrier integrity was compared between groups: control (0 Gy), irradiation only, 12 Gy + LR, 12 Gy + IFN-β, and 12 Gy + LR-IFN-β. Luminex assay of plasma and intestinal cells were also assayed at day 5 after WAI for radiation-induced inflammatory cytokines, and fecal matter was analyzed for LR-IFN-β clearance and levels of the LR-derived IFN-β gene from day 1 to 5 in control non-irradiated mice. Moreover, fluorescent beads were intraorally administered three hours prior to sacrifice at days 2 or 5 after WAI, and blood was assayed for beads.

RESULTS

Mice receiving LR-IFN-β (109 bacteria in 100 mL of saline) 24-hours following a single fraction of 19.75 Gy WAI showed improved OS compared to control irradiated mice (p = 0.03). LR-IFN-β gavage maintained intestinal barrier integrity (p < 0.05) by stimulating intestinal stem cells regenerations (improved levels of Lgr5+ cells, occludin, and I-CAM; p < 0.05), and reduced levels of intestinal pro-inflammatory cytokines, including IFN-γ (p = 0.0261), IL-3 (p < 0.0020) and IL-17 (p < 0.0070). There was no significant effect of control LR or intraperitoneal injection of IFN-β protein at 24 hours after WAI. Detectable levels of LR-IFN-β bacteria were also cleared from fecal matter by day three via colony assay and rt-PCR, with no detectable growth of LR-IFN-β in blood from gavaged irradiated mice (13.5 Gy WAI).

CONCLUSION

LR-IFN-β is both a feasible and effective radiation mitigator that could potentially improve the management of ovarian cancer patients. Furthermore, the subsequent addition of platinum/taxane-based chemotherapy to the combination of WAI and LR-IFN-β should reduce tumor volume while protecting the intestine and thus improve overall survival in ovarian cancer patients.

142 FRAILTY IDENTIFICATION AND INTERDISCIPLINARY ASSESSMENT OF OLDER PEOPLE IN THE EMERGENCY DEPARTMENT

Background

Older People are attending Emergency Departments (EDs) in increasing numbers but the optimal assessment measures to use have yet to be established. This study examined the clinical utility of different assessments of strength, functional mobility, sarcopenia, cognition and frailty used by the physiotherapist in an interdisciplinary team (IDT) in the ED and determined any associations with clinical outcomes.

Methods

This observational cross-sectional study recruited adults ≥70 years who were assessed by an IDT on weekdays during working hours. Demographic variables such as age, gender, social situation, baseline mobility, falls and clinical measures such as Clinical Frailty Scale (CFS), 4AT, hand-held dynamometry, calf circumference and functional mobility in ED were recorded. Clinical outcomes were admission to hospital, discharge from ED with onward referral (ambulatory care or community) and discharge from ED with no referral. Ethical approval was obtained and SPSS was used for statistical analysis.

Results

Two hundred and fifty four participants were recruited, 58.3% female, mean age 80.23 (SD 6.56). Median CFS was 4 (IRQ 2.0), range 1–7 with 32.7% (n = 83) considered frail. Sarcopenia prevalence was 89.3% using grip strength and 7.1% using calf circumference. Grip strength predicted frailty even after adjusting for age (p &lt; 0.0001), gender (p &lt; 0.0001) and falls (p = 0.043). Admission to hospital was predicted by major diagnostic category (p = 0.016) and inability to sit to stand independently in ED (p &lt; 0.0001). Seventy percent (n = 179) of participants were discharged from ED, with 27.6% referred to ambulatory care or community services. Onward referral was predicted by frailty (p = 0.016) and falls in the last six months (p = 0.028).

Conclusion

Grip strength in addition to a validated tool such as CFS may assist an experienced IDT in identifying frailty, which can in turn inform decision-making regarding ED disposition and pathways of care for older people. Functional assessment in the ED is also important to determine the need for hospital admission.

Home FIRsT: interdisciplinary geriatric assessment and disposition outcomes in the Emergency Department

BACKGROUND

Older people in the Emergency Department (ED) are clinically heterogenous and some presentations may be better suited to alternative out-of-hospital pathways. A new interdisciplinary comprehensive geriatric assessment (CGA) team (Home FIRsT) was embedded in our acute hospital's ED in 2017.

AIM

To evaluate if routinely collected CGA metrics were associated with ED disposition outcomes.

DESIGN

Retrospective observational study.

METHODS

We included all first patients seen by Home FIRsT between 7^th May and 19^th October 2018. Collected measures were sociodemographic, baseline frailty (Clinical Frailty Scale), major diagnostic categories, illness acuity (Manchester Triage Score) and cognitive impairment/delirium (4AT). Multivariate binary logistic regression models were computed to predict ED disposition outcomes: hospital admission; discharge to GP and/or community services; discharge to specialist geriatric outpatients; discharge to the Geriatric Day Hospital.

RESULTS

In the study period, there were 1,045 Home FIRsT assessments (mean age 80.1 years). For hospital admission, strong independent predictors were acute illness severity (OR 2.01, 95% CI 1.50-2.70, P<0.001) and 4AT (OR 1.26, 95% CI 1.13 - 1.42, P<0.001). Discharge to specialist outpatients (e.g. falls/bone health) was predicted by musculoskeletal/injuries/trauma presentations (OR 6.45, 95% CI 1.52 - 27.32, P=0.011). Discharge to the Geriatric Day Hospital was only predicted by frailty (OR 1.52, 95% CI 1.17 - 1.97, P=0.002). Age and sex were not predictive in any of the models.

CONCLUSIONS

Routinely collected CGA metrics are useful to predict ED disposition. The ability of baseline frailty to predict ED outcomes needs to be considered together with acute illness severity and delirium.

Opt-out screening for HIV, hepatitis B and hepatitis C: observational study of screening acceptance, yield and treatment outcomes

BACKGROUND

We initiated an emergency department (ED) opt-out screening programme for HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) at our hospital in Dublin, Ireland. The objective of this study was to determine screening acceptance, yield and the impact on follow-up care.

METHODS

From July 2015 through June 2018, ED patients who underwent phlebotomy and could consent to testing were tested for HIV, HBV and HCV using an opt-out approach. We examined acceptance of screening, linkage to care, treatment and viral suppression using screening programme data and electronic health records. The duration of follow-up ranged from 1 to 36 months.

RESULTS

Over the 36-month study period, there were 140 550 ED patient visits, of whom 88 854 (63.2%, 95% CI 63.0% to 63.5%) underwent phlebotomy and 54 817 (61.7%, 95% CI 61.4% to 62.0%) accepted screening for HIV, HBV and HCV, representing 41 535 individual patients. 2202 of these patients had a positive test result. Of these, 267 (12.1%, 95% CI 10.8% to 13.6%) were newly diagnosed with an infection and 1762 (80.0%, 95% CI 78.3% to 81.7%) had known diagnoses. There were 38 new HIV, 47 new HBV and 182 new HCV diagnoses. 81.5% (95% CI 74.9% to 87.0%) of known patients who were not linked were relinked to care after screening. Of the new diagnoses, 86.2% (95% CI 80.4 to 90.8%) were linked to care.

CONCLUSION

Although high proportions of patients had known diagnoses, our programme was able to identify many new infected patients and link them to care, as well as relink patients with known diagnoses who had been lost to follow-up.

Utilising magnetic resonance imaging as the gold-standard in management of suspected scaphoid fractures in the emergency department setting

Scaphoid fractures are the most common carpal bone fracture. Up to 40% of scaphoid fractures can be missed at initial presentation and investigation. Follow-up plain film radiograph has overall poor sensitivity and reliability. MRI has been shown to have an almost 100% sensitivity and specificity and so is the gold standard in scaphoid fracture diagnosis. Additionally, early specialist involvement is recommended. We proposed that following a designated pathway, there would be no significant increase in MRI requests. Following implementation of a pathway for the management of suspected scaphoid fractures in St James's Hospital in 2012 re-auditing demonstrated that management changed to either MRI directly after initial x-ray (16/145, 11%), MRI after second x-ray (9/28, 32%) or orthopaedic follow-up (19/28, 68%). The number of MRIs requested was consistent with our predictors of demand. Thus, our new protocol maximises diagnostics, cost effectiveness and quality of patient care.

Opt-Out Panel Testing for HIV, Hepatitis B and Hepatitis C in an Urban Emergency Department: A Pilot Study

OBJECTIVES

Studies suggest 2 per 1000 people in Dublin are living with HIV, the level above which universal screening is advised. We aimed to assess the feasibility and acceptability of a universal opt-out HIV, Hepatitis B and Hepatitis C testing programme for Emergency Department patients and to describe the incidence and prevalence of blood-borne viruses in this population.

METHODS

An opt-out ED blood borne virus screening programme was piloted from March 2014 to January 2015. Patients undergoing blood sampling during routine clinical care were offered HIV 1&2 antibody/antigen assay, HBV surface antigen and HCV antibody tests. Linkage to care where necessary was co-ordinated by the study team. New diagnosis and prevalence rates were defined as the new cases per 1000 tested and number of positive tests per 1000 tested respectively.

RESULTS

Over 45 weeks of testing, of 10,000 patient visits, 8,839 individual patient samples were available for analysis following removal of duplicates. A sustained target uptake of >50% was obtained after week 3. 97(1.09%), 44(0.49%) and 447(5.05%) HIV, Hepatitis B and Hepatitis C tests were positive respectively. Of these, 7(0.08%), 20(0.22%) and 58(0.66%) were new diagnoses of HIV, Hepatitis B and Hepatitis C respectively. The new diagnosis rate for HIV, Hepatitis B and Hepatitis C was 0.8, 2.26 and 6.5 per 1000 and study prevalence for HIV, Hepatitis B and Hepatitis C was 11.0, 5.0 and 50.5 per 1000 respectively.

CONCLUSIONS

Opt-out blood borne viral screening was feasible and acceptable in an inner-city ED. Blood borne viral infections were prevalent in this population and newly diagnosed cases were diagnosed and linked to care. These results suggest widespread blood borne viral testing in differing clinical locations with differing population demographic risks may be warranted.

Socioeconomic deprivation does not affect prescribing of secondary prevention in patients with peripheral arterial disease

AIM

Aim of the study was to assess the effect of socioeconomic deprivation on prescribing of cardiovascular secondary prevention medications in patients referred with peripheral arterial disease (PAD).

METHODS

A retrospective review of vascular clinic referrals was performed. All patients referred from primary care with suspected PAD over a two month period were included. The deprivation score, prescription of cardiovascular secondary prevention medications, smoking status and the presence of cardiovascular co-morbidities (coronary artery or cerebrovascular disease--CAD/CVD) were assessed. Comparison was made between socioeconomic groups using the Carstairs Deprivation (DepCat) Score and between patients with and without a history of currently existing cardiovascular co-morbidities.

RESULTS

The study included 391 patients. Almost two thirds of patients (253) were from the most deprived socioeconomic groups and were significantly younger at presentation (median age DepCat 7: 63 yrs, DepCat 1-2: 74.5 yrs, P<0.0001). The majority of patients with a prior history of CAD/CVD were prescribed secondary preventative medications at the time of referral with suspected PAD whereas those with no prior history of CAD/CVD, (212 patients, 54%) were significantly less likely to be prescribed antiplatelets (47% vs. 83%), statins (45% vs. 86%) or ACEi/ARBs (29% vs. 68%) (all P<0.05). Secondary prevention prescribing did not differ between socioeconomic groups.

CONCLUSION

Secondary prevention prescribing is inadequate in patients with suspected PAD regardless of socioeconomic group and is significantly lower in those without previously diagnosed CAD/CVD. There remains a lack of appreciation of the high cardiovascular risk associated with PAD.

Sources of nitrogen dioxide (NO2) in New Zealand homes: findings from a community randomized controlled trial of heater substitutions

Houses in New Zealand have inadequate space heating and a third of households use unflued gas heaters. As part of a large community intervention trial to improve space heating, we replaced ineffective heaters with more effective, non-polluting heaters. This paper assesses the contribution of heating and household factors to indoor NO2 in almost 350 homes and reports on the reduction in NO2 levels due to heater replacement. Homes using unflued gas heaters had more than three times the level of NO2 in living rooms [geometric mean ratio (GMR) = 3.35, 95% CI: 2.83-3.96, P < 0.001] than homes without unflued gas heaters, whereas homes using gas stove-tops had significantly elevated living room NO2 levels (GMR = 1.42, 95% CI: 1.05-1.93, P = 0.02). Homes with heat pumps, flued gas heating, or enclosed wood burners had significantly lower levels of NO2 in living areas and bedrooms. In homes that used unflued gas heaters as their main form of heating at baseline, the intervention was associated with a two-third (67%) reduction in NO2 levels in living rooms, when compared with homes that continued to use unflued gas heaters. Reducing the use of unflued gas heating would substantially lower NO2 exposure in New Zealand homes.

PRACTICAL IMPLICATIONS

Understanding the factors influencing indoor NO2 levels is critical for the assessment and control of indoor air pollution. This study found that homes that used unflued gas combustion appliances for heating and cooking had higher NO2 levels compared with homes where other fuels were used. These findings require institutional incentives to increase the use of more effective, less polluting fuels, particularly in the home environment.

Günter Blobel--still passionate after all these years

What one word best describes Günter Blobel?

ANSWER

passion. Almost all of the nearly 200 investigators who have worked in the Blobel laboratory in the past quarter century would describe him as highly enthusiastic, intense and, above all, passionate. Whether it was in the early days of the signal hypothesis, the initial characterization of nuclear pores and lamina or his more recent foray into rebuilding the historic German City of Dresden, Günter attacks every project with unbridled passion, intensity, boundless energy and determination.

Intracellular localization of phospholipase D1 in mammalian cells

Phospholipase D (PLD) hydrolyzes phosphatidylcholine to generate phosphatidic acid. In mammalian cells this reaction has been implicated in the recruitment of coatomer to Golgi membranes and release of nascent secretory vesicles from the trans-Golgi network. These observations suggest that PLD is associated with the Golgi complex; however, to date, because of its low abundance, the intracellular localization of PLD has been characterized only indirectly through overexpression of chimeric proteins. We have used highly sensitive antibodies to PLD1 together with immunofluorescence and immunogold electron microscopy as well as cell fractionation to identify the intracellular localization of endogenous PLD1 in several cell types. Although PLD1 had a diffuse staining pattern, it was enriched significantly in the Golgi apparatus and was also present in cell nuclei. On fragmentation of the Golgi apparatus by treatment with nocodazole, PLD1 closely associated with membrane fragments, whereas after inhibition of PA synthesis, PLD1 dissociated from the membranes. Overexpression of an hemagglutinin-tagged form of PLD1 resulted in displacement of the endogenous enzyme from its perinuclear localization to large vesicular structures. Surprisingly, when the Golgi apparatus collapsed in response to brefeldin A, the nuclear localization of PLD1 was enhanced significantly. Our data show that the intracellular localization of PLD1 is consistent with a role in vesicle trafficking from the Golgi apparatus and suggest that it also functions in the cell nucleus.

Inhibition of phosphatidic acid synthesis alters the structure of the Golgi apparatus and inhibits secretion in endocrine cells

In mammalian cells, activation of a Golgi-associated phospholipase D by ADP-ribosylation factor results in the hydrolysis of phosphatidylcholine to form phosphatidic acid (PA). This reaction stimulates the release of nascent secretory vesicles from the trans-Golgi network of endocrine cells. To understand the role of PA in mediating secretion, we have exploited the transphosphatidylation activity of phospholipase D. Rat anterior pituitary GH3 cells, which secrete growth hormone and prolactin, were treated with 1-butanol resulting in the synthesis of phosphatidylbutanol rather than PA. Under these conditions transport from the ER through the Golgi apparatus and secretion of polypeptide hormones were inhibited quantitatively. Furthermore, the in vitro synthesis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)) by Golgi membranes was inhibited quantitatively. Most significantly, in the presence of 1-butanol the architecture of the Golgi apparatus was disrupted, resulting in its disassembly and fragmentation. Removal of the alcohol resulted in the rapid restoration of Golgi structure and secretion of growth hormone and prolactin. Our results suggest that PA stimulation of PtdIns(4,5)P(2) synthesis is required for maintaining the structural integrity and function of the Golgi apparatus.

Raised plasma homocysteine as a risk factor for retinal vascular occlusive disease

BACKGROUND/AIMS

A moderately elevated plasma concentration of the sulphur amino acid homocysteine is an independent risk factor for atherosclerotic vascular disease. Many of the risk factors associated with coronary, cerebral, and peripheral atherosclerotic vascular disease are common to retinal vascular occlusive disease but it is unclear whether elevated plasma concentrations of homocysteine are also associated with such disease. This study assessed the relation between retinal vascular occlusive disease and elevated levels of plasma total homocysteine (tHcy).

METHODS

A retrospective case-control study involving hospital based controls and cases with retinal artery, central retinal vein (including hemiretinal vein), and branch retinal vein occlusions was performed. The relation between elevated tHcy, defined as a level greater than or equal to 12 micromol/l and risk of retinal vascular occlusive disease was examined.

RESULTS

87 cases of retinal vascular occlusive disease including 26 cases of retinal artery occlusion, 40 cases with central retinal vein occlusion, and 21 cases of branch retinal vein occlusion were compared with 87 age matched controls. Mean tHcy levels were higher in all disease groups and this difference was significant in patients with retinal artery occlusions (p= 0.032) and patients with central retinal vein occlusion (p=0.0001). When adjusted for known cardiovascular risk factors, tHcy was an independent risk factor for retinal vascular occlusive disease (OR 2.85 (95% CI 1.43-5.68)).

CONCLUSIONS

Elevated tHcy is an independent risk factor for retinal vascular occlusive disease. Assessment of tHcy may be important in the investigation and management of patients with retinal vascular occlusive disease.

Serum amyloid A in the assessment of early inflammatory arthritis

OBJECTIVE

Acute phase serum amyloid A (A-SAA) has been reported to be more sensitive than C-reactive protein (CRP) as a marker of disease activity. It may function in immune regulation and is linked to the development of secondary amyloidosis. We investigated the profile of A-SAA in early inflammatory arthritis and compared A-SAA with CRP and erythrocyte sedimentation rate (ESR) in relation to diagnosis and disease activity.

METHODS

Using a sensitive and specific ELISA, A-SAA was measured in the serum of 140 patients with early arthritis (disease duration 2 weeks to 24 mo, mean 6 mo). CRP was determined using a standard ELISA; ESR and clinical disease activity variables were also recorded.

RESULTS

Sixty-four patients had rheumatoid arthritis (RA), 19 psoriatic arthritis (PsA), 28 undifferentiated arthritis (UA), and 29 other forms of arthritis. A-SAA levels correlated with both CRP (r = 0.73, p = 0.0001) and ESR (r = 0.6, p = 0.0001). The magnitude of the A-SAA response was greater than either the CRP or ESR, and very high A-SAA levels were observed in disease as early as 2 weeks. Highest A-SAA concentrations occurred in RA (median 70.3 mg/l, maximum 1542) compared with the other groups (medians, PsA: 33 mg/l; UA: 12.3 mg/l; other arthritis: 11.2 mg/l), with values > 520 mg/l observed exclusively in RA. A-SAA, unlike CRP or ESR, could distinguish patients with a final diagnosis of RA from those who had persistent UA. In RA, A-SAA provided the strongest correlations with clinical measurements of disease activity. Clinical improvement was also best represented by A-SAA, while disease deterioration was associated with a significant increase in A-SAA values, but not CRP or ESR.

CONCLUSION

Compared with ESR or CRP, A-SAA correlates best with markers of disease activity, and in patients with recent onset arthritis, very high levels of SAA occur exclusively in RA. As A-SAA is sensitive to change and accurately reflects alterations in disease status, it is the best marker available for the assessment of inflammatory joint disease.

Pseudoautosomal gene: possible association with bipolar males but not with schizophrenia

The phenomenon of anticipation has been demonstrated in several neuropsychiatric disorders and suggested for schizophrenia and bipolar affective disorder. Many conditions exhibiting anticipation have been shown to be caused by trinucleotide repeat (CAG/CTG) expansions. Some evidence suggests that these expansions also exist in individuals with schizophrenia and bipolar affective disorder. In this investigation, we analysed a polymorphic CAG repeat in the interleukin receptor gene (IL9R), mapped to the pseudoautosomal region Xq28 and Yq21 (a candidate region for schizophrenia and affective disorder). Two common alleles, differing by one repeat unit and two rare alleles were found in cases and controls. Allele frequencies of this repeat were investigated in Irish schizophrenic, bipolar disorder and ethnically matched control samples. We found no evidence of an increased frequency of larger CAG repeats in either the schizophrenic or bipolar affective disorder samples as a whole when compared to the controls. However, dividing the samples by sex demonstrated a significant association between bipolar affective disorder males and the larger allele (allele 2) (patients 54.8% vs controls 40.1%, chi2 = 6.7, P = 0.009). In addition, a decreased frequency of this allele has been observed in the female patients, but did not attain statistical significance (patients 37% vs controls 46%, chi2 = 2.1, P = 0.14). This provides preliminary evidence that this locus or a closely mapped DNA variant (in linkage disequilibrium with the CAG repeat) may be involved in the genetic susceptibility to bipolar affective disorder in males.

Disease models provide insights into post-golgi protein trafficking, localization and processing

Over the past two years, the use of in vitro systems and the identification of autoantibodies to Golgi proteins have provided important new tools for analyzing vesicle and cargo trafficking in the distal secretory pathway. In addition, the phenotypic characterization of mice with knockouts of various prohormone convertases has led to significant progress in understanding the biological relevance of prohormone processing in post-Golgi compartments.

Biosynthesis and packaging of carboxypeptidase D into nascent secretory vesicles in pituitary cell lines

Metallocarboxypeptidase D (CPD) is a membrane-bound trans-Golgi network (TGN) protein. In AtT-20 cells, CPD is initially produced as a 170-kDa endoglycosidase H-sensitive glycoprotein. Within 30 min of chase, the CPD increases to 180 kDa and is resistant to endoglycosidase H as a result of carbohydrate maturation. CPD also undergoes an activation step required for binding to a substrate affinity resin. Blocking the protein exit from the endoplasmic reticulum inhibits the increase in molecular mass but not the step required for affinity column binding, suggesting that enzyme activation precedes carbohydrate maturation and that these reactions occur in distinct intracellular compartments. Only the higher molecular weight mature CPD enters nascent secretory vesicles, which bud from the TGN of permeabilized AtT-20 and GH3 cells. The budding efficiency of CPD into vesicles is 2-3-fold lower than that of endogenous proopiomelanocortin in AtT-20 cells or prolactin in GH3 cells. In contrast, the packaging of a truncated form of CPD, which lacks the cytoplasmic tail and transmembrane domain, was similar to that of proopiomelanocortin. Taken together, the results support the proposal that CPD functions in the TGN in the processing of proteins that transit the secretory pathway and that the C-terminal region plays a major role in TGN retention.

The use of permeabilized cells to investigate secretory granule biogenesis

To investigate the mechanism of secretory granule biogenesis in endocrine cells, our laboratory used rat anterior pituitary GH3 cells which secrete growth hormone and prolactin. Here we describe a simple and rapid procedure for generating permeabilized cells to dissect molecular mechanisms involved in nascent secretory vesicle budding from the trans-Golgi network (TGN). Using this system, we demonstrate that vesicle budding is temperature, energy, and cytosol dependent; in addition, cytosol from a variety of cells, including yeast (Saccharomyces cerevisiae), can support vesicle release. The budding of nascent secretory vesicles from the TGN is stimulated by a phospholipase D activity that is associated with Golgi membranes. Our results suggest that phospholipid metabolism plays an important role in the release of nascent secretory vesicles from the TGN.

Temperature-induced conformational changes in prosomatostatin-II: implications for processing

Somatostatin (SRIF) is a 14-residue peptide hormone synthesized in the hypothalamus and pancreatic islets. SRIF-14 and an N-terminally extended form, SRIF-28, are generated by the proteolytic processing of an approx. 102-residue precursor prosomatostatin (proSRIF) at a single set of paired basic residues (Arg-Lys) and at a monobasic (Arg) site respectively. Previous work in our laboratory demonstrated that the propeptide of SRIF mediates intracellular sorting; we suggested that this information resides in the prohormone structure. To identify putative sorting domains we have investigated structural features of recombinant anglerfish proSRIF-II purified from Escherichia coli. Two species of proSRIF-II were obtained: a monomeric form and a disulphide-linked dimer. CD analyses revealed that monomeric proSRIF-II lacks appreciable periodic secondary structure; however, on slow heating (2 degrees C/min) and cooling, it assumed a predominantly alpha-helical conformation. When subjected to a second heating-and-cooling cycle, the alpha-helical conformation was maintained. In contrast, the dimeric form of proSRIF-II was predominantly alpha-helical and its helicity did not increase in response to heating and recooling. Our results suggest that proSRIF-II might exist in several different folding intermediate states.