Endoscopic Versus Conservative Therapy for Bleeding Peptic Ulcer with Adherent Clot: A Comprehensive Systematic Review and Meta-Analysis

INTRODUCTION

Peptic ulcers with adherent clots are associated with a high-risk of rebleeding and mortality. However, the optimal management of bleeding ulcers with adherent clots remains unclear. We conducted this systematic review and meta-analysis to compare endoscopic therapy and conservative therapy to manage bleeding ulcers with adherent clots.

METHODS

We systematically searched PubMed, Embase, and Web of Science databases through October 2022 to include all studies comparing the endoscopic and conservative therapeutic approaches for bleeding ulcers with adherent clots. Our primary outcome was rebleeding (overall and 30-day). The secondary outcomes were mortality (overall and 30-day), need for surgery, and length of hospital stay (LOS). The random-effects model was used to calculate the pooled odds ratios (OR) and mean differences (MD) with the corresponding confidence intervals (CI) for proportional and continuous variables, respectively.

RESULTS

Eleven studies (9 RCTs) with 833 patients (431 received endoscopic therapy vs. 402 received conservative therapy) were included. Overall, endoscopic therapy was associated with lower overall rebleeding (OR 0.41, 95% CI 0.22-0.79, P = 0.007), 30-day rebleeding (OR 0.43, 95% CI 0.21-0.89, P = 0.002), overall mortality (OR 0.47, 95% CI 0.23-0.95, P = 0.04), 30-day mortality (OR 0.43, 95% CI 0.21-0.89, P = 0.002), need for surgery (OR 0.44, 95% CI 0.21-0.95, P = 0.04), and LOS (MD - 3.17 days, 95% CI - 4.14, - 2.19, P < 0.00001). However, subgroup analysis of randomized controlled trials (RCTs) showed no significant difference in overall mortality (OR 0.78, 95% CI 0.24-2.52, P = 0.68) between the two strategies, with numerically lower but statistically non-significant rates of overall rebleeding (7.2% vs. 18.5%, respectively; OR 0.42, 95% CI 0.17-1.05, P = 0.06), statistically lower rate of need for surgery (OR 0.28, 95% CI 0.08-0.96, P = 0.04) with endoscopic therapy compared to conservative therapy.

CONCLUSIONS

Our meta-analysis demonstrates that endoscopic therapy was overall associated with lower rates of rebleeding (overall and 30-day), mortality (overall and 30-day), need for surgery, and LOS, compared to conservative therapy for the management of bleeding ulcers with adherent clots. However, subgroup analysis of RCTs showed that endoscopic therapy was associated with numerically lower but statistically non-significant rates of overall rebleeding and a statistically lower rate of need for surgery compared to conservative therapy with similar overall mortality rates. Combined treatment with thermal therapy and injection therapy was the most effective treatment modality in reducing rebleeding risk. Further large-scale RCTs are needed to validate our findings.

Primary sclerosing cholangitis hospitalizations in the United States: characteristics and predictors of clinical outcomes

Background

Primary sclerosing cholangitis (PSC) is a chronic progressive disease that primarily affects the medium and large biliary ducts.

Methods

This study investigated the baseline characteristics and predictors of clinical outcomes among hospitalized patients with PSC in the US. Using the National Inpatient Sample database from 2018 to 2020, we included adults with a principal diagnosis of PSC.

Results

Our study included 2585 adult hospitalizations. The prevalence of cirrhosis, ulcerative colitis (UC), Crohn's disease (CD), and cholangiocarcinoma among hospitalized PSC patients was 44.5%, 32.3%, 13.15%, and 5.2%, respectively. Over a third of patients (38.1%) underwent endoscopic retrograde cholangiopancreatography (ERCP). UC, CD, cholangiocarcinoma, and autoimmune hepatitis had no impact on mortality, length of stay, or ERCP utilization. Interestingly, individuals of Asian/Pacific Islander ethnicity had higher odds of undergoing ERCP compared to White ethnicity (odds ratio 4.67, 95% confidence interval 1.25-17.4). Conversely, patients with cirrhosis and liver transplant recipients were less likely to undergo ERCP.

Conclusion

This is the first nationwide study to assess the clinical characteristics and outcomes of hospitalized patients with PSC. It highlights various factors associated with increased utilization of ERCP, longer length of stay, and increased inpatient mortality. Further research is warranted to explore these associations.

Lumen-Apposing Metal Stent With and Without Concurrent Double-Pigtail Plastic Stent for Pancreatic Fluid Collections: A Comparative Systematic Review and Meta-Analysis

Background

Lumen-apposing metal stents (LAMSs) are often used to drain pancreatic fluid collections (PFCs). However, adverse events, such as stent obstruction, infection, or bleeding, have been reported. Concurrent double-pigtail plastic stent (DPPS) deployment has been suggested to prevent these adverse events. This meta-analysis aimed to compare the clinical outcomes of LAMS with DPPS vs. LAMS alone in the drainage of PFCs.

Methods

An extensive search was conducted in the literature to include all the eligible studies that compared LAMS with DPPS vs. LAMS alone for drainage of PFCs. Pooled risk ratios (RRs) with the 95% confidence intervals (CIs) were obtained within a random-effect model. The outcomes were technical and clinical success, and overall adverse events, including stent migration and occlusion, bleeding, infection, and perforation.

Results

Five studies involving 281 patients with PFCs (137 received LAMS plus DPPS vs. 144 received LAMS alone) were included. LAMS plus DPPS group was associated with comparable technical success (RR: 1.01, 95% CI: 0.97 - 1.04, P = 0.70) and clinical success (RR: 1.01, 95% CI: 0.88 - 1.17). Lower trends of overall adverse events (RR: 0.64, 95% CI: 0.32 - 1.29), stent occlusion (RR: 0.63, 95% CI: 0.27 - 1.49), infection (RR: 0.50, 95% CI: 0.15 - 1.64), and perforation (RR: 0.42, 95% CI: 0.06 - 2.78) were observed in LAMS with DPPS group compared to LAMS alone but without a statistical significance. Stent migration (RR: 1.29, 95% CI: 0.50 - 3.34) and bleeding (RR: 0.65, 95% CI: 0.25 - 1.72) were similar between the two groups.

Conclusions

Deployment of DPPS across LAMS for drainage of PFCs has no significant impact on efficacy or safety outcomes. Randomized, controlled trials are necessary to confirm our study results, especially in walled-off pancreatic necrosis.

Real-world effectiveness of COVID-19 vaccination in liver cirrhosis: a systematic review with meta-analysis of 51,834 patients

SARS-CoV-2 vaccinations were found to be highly effective in phase 3 clinical trials. However, these trials have not reported data regarding the subgroup of liver disease or excluded patients with liver disease. The effectiveness of COVID-19 vaccines among liver cirrhosis (LC) patients is unclear. We conducted this meta-analysis to assess the effectiveness of SARS-CoV-2 vaccination in LC patients. A comprehensive literature search was conducted to include all the relevant studies that compared the outcomes of LC patients who received SARS-CoV-2 vaccines vs. unvaccinated patients. Pooled risk ratios (RRs) with 95% confidence intervals (CIs) were calculated by the Mantel-Haenszel method within a random-effect model. Four studies with 51,834 LC patients (20,689 patients received at least one dose vs 31,145 were unvaccinated) were included. COVID-19-related complications, including hospitalization (RR 0.73, 95% CI 0.59-0.91, P = 0.004), mortality (RR 0.29, 95% CI 0.16-0.55, P = 0.0001), and need for invasive mechanical ventilation (RR 0.29, 95% CI 0.11-0.77, P = 0.01), were significantly lower in the vaccinated group compared to the unvaccinated group. SARS-CoV-2 vaccination in LC patients reduced COVID-19-related mortality, intubation, and hospitalization. SARS-CoV-2 vaccination is highly effective in LC. Further prospective studies, preferably randomized controlled trials, are necessary to validate our findings and determine which vaccine is superior in patients with LC.

Abstract P254: Effect Of Covid-19 Infection On Qtc Prolongation

Background Objective: What is the association between COVID-19 infection and QTc changes? Coronavirus SARS-COV2 uses angiotensin-converting enzyme receptors 2 (ACE2) on host cells to enter into human cells. These receptors are expressed on the heart cells among other major cells. This is one of the most accepted theories for direct cardiac cell injury of COVID-19disease and associated cardiorespiratory manifestations. COVID-19 infection leads to unstable myocardial cell membranes, by causing hypoxia, myocarditis, myocardial ischemia, and abnormal host immune response. This is the main reason behind Arrhythmia and EKG changes during COVID19 infection. But the specific effect on QTc has not been studied well so far, so our research try to study this connection.

Method: This is an observational retrospective hospital chart review involving 320 adult participants diagnosed with COVID-19 infection at our facility. After applying the exclusion criteria, 130 participants remained, who were distributed into two groups. One group with long QTc and one group with normal QTc. Data was collected and demographics were recorded using Excel and SPSS, then compared using a student’s t-test for independent groups. The quantitative data are summarized by the mean and standard deviation (SD). Statistical significance was taken as P <0.05.

Result: A total of 63 participants (48.4% of total 130 participants) met the criteria for long QTc, and a total of 67 participants(51.5%) had normal QTc (P < 0.001). There was no statistically significant mortality outcome (0.8% vs. 3.8%, P = 0.21).

Conclusion: Our study showed 48.4% participants having an increase in QTc during COVID-19 infection, (20% of 320 total admissions). This observation is very important to help healthcare providers to gaina better understanding of this disease.

High-Flow Nasal Cannula Versus Noninvasive Ventilation in Patients With COVID-19

BACKGROUND

High-flow nasal cannula (HFNC) oxygen and noninvasive ventilation (NIV) have been widely used in patients with acute hypoxic respiratory failure (AHRF) due to COVID-19. However, the impact of HFNC versus NIV on clinical outcomes of COVID-19 is uncertain. Therefore, we performed this meta-analysis to evaluate the effect of HFNC versus NIV in COVID-19-related AHRF.

METHODS

Several electronic databases were searched through February 10, 2022, for eligible studies comparing HFNC and NIV in COVID-19-related AHRF. Our primary outcome was intubation. The secondary outcomes were mortality, hospital length of stay (LOS), and P_aO2 /F_IO2 changes. Pooled risk ratio (RR) and mean difference (MD) with the corresponding 95% CI were obtained using a random-effect model. Prediction intervals were calculated to indicate the variance in outcomes that would be expected if new studies were conducted in the future.

RESULTS

Nineteen studies involving 3,606 subjects (1,880 received HFNC and 1,726 received NIV) were included. There were no differences in intubation (RR 1.01 [95% CI 0.85-1.20], P = .89) or LOS (MD 0.38 d [95% CI -0.61 to 1.37], P = .45) between groups, with consistent results on the subgroup of randomized controlled trials (RCTs). Mortality was lower in NIV (RR 0.81 [95% CI 0.66-0.98], P = .03). However, the prediction interval was 0.41-1.59, and subgroup analysis of RCTs showed no difference in mortality between groups. There was a greater improvement in P_aO2 /F_IO2 with NIV (MD 22.80 [95% CI 5.30-40.31], P = .01).

CONCLUSIONS

Our study showed that despite the greater improvement in P_aO2 /F_IO2 with NIV, intubation rates and LOS were similar between HFNC and NIV. Although mortality was lower with HFNC than NIV, the prediction interval included the null value, and there was no difference in mortality between HFNC and NIV on a subgroup of RCTs. Future large-scale RCTs are necessary to support our findings.

Molecular classification of endometrial carcinoma applied to endometrial atypical hyperplasia biopsy specimens

e17622

Background: 50% of endometrial atypical hyperplasia (AH) cases on endometrial sampling have concurrent endometrial cancer (EC) on hysterectomy. Little data exists regarding molecular signatures that can predict the presence of concurrent endometrial cancer in patients with AH on biopsy. Therefore, we set to characterize molecular landscapes of endometrial samples diagnosed with AH with EC on the final hysterectomy specimen, using matched controls. Methods: Karmanos Cancer Institute pathology database was searched for patients with AH on endometrial curettage or biopsy who had a hysterectomy within 6 months. Only samples with adequate tissue for next generation sequencing were included. In total, 59 tissue samples from 34 patients were included: there were 15 AH endometrial biopsy samples, 18 AH final hysterectomy samples (13 matched pairs), 13 EC endometrial biopsies and 13 samples that were EC on final hysterectomy samples (12 matched pairs) that were analyzed using next-generation sequencing (WES) and/or whole transcriptome sequencing (WTS) (NovaSeq). TMB was measured by counting all somatic mutations found per tumor (TMB-high: >10 mutations per MB). Immune cell infiltrates were calculated by Quantiseq. Significance was determined using Fisher exact, Chi-square and Mann-Whitney U test and adjusted for multiple comparisons: p < 0.05 but q > 0.05 was considered a trend. Results: Clinical analysis demonstrated 15/34 patients with endometrial AH on initial sampling and EC on the final hysterectomy. 2 out of 15 patients were > stage II at time of surgery. Molecularly, fewer PTEN mutations were found between AH (2/8) and EC (14/17) on final hysterectomy (25% vs 82.4%, p = 0.01). Samples of EC origin were MSI-H by NGS-MSI (3/18) and had no mutations in PPP2R1A (0/16). Comparing hysterectomy samples, EC trended toward increased CTLA4 (FC: 6.97-fold) expression and immune cell infiltration of Macrophage M1 (+1.19%), NK cells (+2.13%), CD8+ T Cells (+1.27%), regulatory T cells (+2.17%) and Dendritic cells (+2.87%) compared to AH samples (all p < 0.05). Similarly, when comparing endometrial biopsies, EC samples trended toward increased expression of CTLA4 (12.6-fold), HAVCR2/TIM3 (FC: 2.59-fold) and IFNG (FC: 17.8-fold) immune checkpoint genes, as well as increased immune cell infiltration of Neutrophils (+11.7%), CD8+ T cells (+2.39%) and regulatory T cells (+2.43%) compared to AH samples (all p < 0.05). Conclusions: There are molecular and tumor microenvironment differences seen between AH endometrial biopsies that have concurrent EC compared to those that do not on the final hysterectomy specimens. These differences may lead to advances in identifying appropriate patients for fertility sparing treatments, versus those that can be managed surgically by a benign gynecologist or a gynecologic oncologist. Analyses with larger sample sizes are needed and are ongoing.

Triglyceride-Glucose Index for Early Prediction of Nonalcoholic Fatty Liver Disease: A Meta-Analysis of 121,975 Individuals

Insulin resistance (IR) is a major contributor to the pathogenesis of nonalcoholic fatty liver disease (NAFLD). The triglyceride-glucose (TyG) index has recently gained popularity for the assessment of IR and NAFLD due to its ease of acquisition and calculation. Therefore, we conducted this systematic review and meta-analysis to summarize the existing studies in the literature and provide a quantitative assessment of the significance of the TyG index in predicting the incidence of NAFLD. A comprehensive literature search in PubMed, EMBASE, and Web of Science databases from inception until 25 March 2022 was conducted. Published observational studies that evaluated the association between TyG index and NAFLD among the adult population and reported the hazard ratio (HR) or odds ratio (OR) for this association after multivariate analysis were included. The random-effects model was used as the primary statistical analysis model in the estimation of pooled ORs and HRs with the corresponding confidence intervals (CIs). A total of 17 observational studies, including 121,975 participants, were included. For studies analyzing the TyG index as a categorical variable, both pooled OR (6.00, CI 4.12–8.74) and HR (1.70, CI 1.28–2.27) were significant for the association between TyG index and incident NAFLD. For studies analyzing the TyG index as a continuous variable, pooled OR (2.25, CI 1.66–3.04) showed similar results. Consistent results were obtained in subgroup analyses according to the study design, sample size, ethnicity, and diabetic status. In conclusion, our meta-analysis demonstrates that a higher TyG index is associated with higher odds of NAFLD. TyG index may serve as an independent predictive tool to screen patients at high risk of NAFLD in clinical practice, especially in primary care settings. Patients with a high TyG index should be referred for a liver ultrasound and start intense lifestyle modifications. However, further large-scale prospective cohort studies are necessary to validate our findings.

567. Reasons for Deferral of COVID-19 Vaccines Among Arab American Healthcare Professionals Living in the United States

Background

The WHO identified the three most common reasons for worldwide vaccine hesitancy to be safety concerns, lack of knowledge and awareness, and religion and cultural issues. There is limited information on this topic among Arab Americans, a rapidly growing demographic in the US. We sought to determine the reasons for deferral of the coronavirus disease 2019 (COVID-19) vaccine amongst Arab American health professionals living in the US.

Methods

This was a cross-sectional study utilizing an anonymous online survey. The survey was distributed via e-mail to National Arab American Medical Association members and Arab-American Center for Economic and Social Services healthcare employees. Respondents were considered vaccine hesitant if they selected responses other than a willingness to receive the COVID-19 vaccine.

Results

A total of 4,000 surveys were sent via e-mail from December 28 2020 to January 31 2021. The highest group of respondents were between the ages of 18-29 years and physicians constituted 48% of the respondents. Among 515 respondents, 41.9% (n=216) would receive the vaccine within one month of it becoming available to them, and 30.2% (n=156) had already received a vaccine. Among those who would defer the vaccine, 9.3% (n=48) would receive it within 1-3 months, 5.6% (n=29) within 3-6 months and 6.6% (n=34) after over 6 months or longer. 6.2% (n=32) would not receive the vaccine. The three most commonly reported reasons for deferral of vaccine among 75 vaccine hesitant respondents were: “I am worried about the side effects” (65.3%), “I am worried the vaccine moved through clinical trials too fast (54.7%), and “There is no information about long term side effects of the vaccine” (52%). Data indicate that about a quarter of respondents also expressed distrust of the government and the pharmaceutical industry. The results are summarized in table 1.

Conclusion

Reasons cited by this sample of Arab Americans for deferring the COVID-19 vaccine mirror more general concerns about vaccine side effects and need for information. Concerns about clinical trial procedures and distrust have become more prevalent with COVID-19. This data can help inform COVID-19 vaccine advocacy efforts among health care providers, and thus could have substantial impact on vaccine attitudes of the general population.

Disclosures

Marcus Zervos, MD, contrafect (Advisor or Review Panel member)janssen (Grant/Research Support)merck (Grant/Research Support)moderna (Grant/Research Support)pfizer (Grant/Research Support)serono (Grant/Research Support)

Evaluation of COVID-19 Vaccine Attitudes among Arab American Healthcare Professionals Living in the United States

BACKGROUND

Vaccine hesitancy is the next great barrier for public health. Arab Americans are a rapidly growing demographic in the United States with limited information on the prevalence of vaccine hesitancy. We therefore sought to study the attitudes towards the coronavirus disease 2019 (COVID-19) vaccine amongst Arab American health professionals living in the United States.

METHODS

This was a cross sectional study utilizing an anonymous online survey. The survey was distributed via e-mail to National Arab American Medical Association members and Arab-American Center for Economic and Social Services healthcare employees. Respondents were considered vaccine hesitant if they selected responses other than a willingness to receive the COVID-19 vaccine.

RESULTS

A total of 4000 surveys were sent via e-mail from 28 December 2020 to 31 January 2021, and 513 responses were received. The highest group of respondents were between the ages of 18-29 years and physicians constituted 48% of the respondents. On multivariable analysis, we found that respondents who had declined an influenza vaccine in the preceding 5 years (p < 0.001) and allied health professionals (medical assistants, hospital administrators, case managers, researchers, scribes, pharmacists, dieticians and social workers) were more likely to be vaccine hesitant (p = 0.025). In addition, respondents earning over $150,000 US dollars annually were less likely to be vaccine hesitant and this finding was significant on multivariable analysis (p = 0.011).

CONCLUSIONS

Vaccine hesitancy among health care providers could have substantial impact on vaccine attitudes of the general population, and such data may help inform vaccine advocacy efforts.

Clinical and pathological characteristics and hormone receptor status of women with breast cancer in the European Gaza Hospital: a retrospective chart-based review

BACKGROUND

Breast cancer is the most common cancer (accounting for 31·3% of all cancers) among women in the Gaza Strip. This audit examines clinical and pathological characteristics of women presenting with breast carcinoma to the European Gaza Hospital (EGH), a governmental hospital and oncological centre serving 600 000 people in the southern Gaza Strip.

METHODS

Data were collected from the records of patients with breast cancer treated at the EGH from March, 2015, to Sept, 2017. 397 cases were identified, including 218 patients with full hormone receptor status (oestrogen, progesterone, and Her2/neu receptor status). Data were analysed using Student's t test.

FINDINGS

The mean age was 54 years (SD 11·2). 64% of the women (139 of 218) were older than 50 years, and 16% (33 of 218) were younger than 40 years. Histological grade was assessed for 56% of the women (122 of 218), and 55% of these women (67 of 122) presented with grade II tumours. Tumour size was documented in 82% of the files (178 of 218), and tumours were 2-5 cm in 47% of the documented cases (83 of 178). Furthermore, 51% of women (112 of 218) tested positive for the presence of cancer cells in lymph nodes, and 6% (14 of 218) had distant metastasis at presentation. The clinical stage at diagnosis was recorded in 56% of cases (122 of 218), of whom 4% (five of 122) presented at stage I, 54% (66 of 122) presented at stage II, and 42% (51 of 122) presented at stage III/IV. Pre-operative histopathology was carried out for 120 women, of whom 85% (102 of 120) had intraductal carcinoma. Only 81% of women (177 of 218) had post-operative histopathology, of whom 79% (139 of 177) had intraductal carcinoma. The histopathological type was significantly different for pre-operative and post-operative specimens (p<0·0001). Oestrogen receptor status was positive in 58% of patients (127 of 218), progesterone receptor status was positive in 57% of patients (124), and HER2/neu receptor was overexpressed in 33% of patients (65). Triple-negative breast cancer (testing negative for oestrogen, progesterone, and HER2/neu) was found in 23% of the women (49) and double-negative breast cancer (testing negative for oestrogen and progesterone but positive for HER2) in 11% of the women (24).

INTERPRETATION

Patients with breast cancer present with advanced disease in the Gaza Strip. HER2/neu overexpression was approximately 10% higher than the percentages reported in the literature for the USA. The significant difference between pre-operative and post-operative specimens' histopathological type could be due to use of fine-needle aspiration. Guidance from the Royal College of Radiologists recommends pre-operative core biopsy. It should be noted that documentation in the patient medical files was incomplete, which is a common obstacle in Gaza that must be tackled for effective improvement in the quality of care.

FUNDING

None.

Management of pregnancy loss in the first trimester: a retrospective audit

BACKGROUND

Early pregnancy loss occurs in 10% of all clinically recognised pregnancies. 80% of pregnancy losses occur in the first trimester. Offering choice and participation in the management decisions is essential to patient-centred care. The aim of this study was to assess the management of first trimester pregnancy loss at the Emirati Hospital in Rafah, Gaza Strip.

METHODS

In this retrospective audit, we compared the management of first trimester pregnancy loss at Emirati Hospital using the American College of Obstetricians and Gynecologists guidelines (ACOG, No. 150, May 2015). Data were obtained from patients' medical records.

FINDINGS

50 cases were identified in November and December, 2015. 32 (64%) cases were missed miscarriages (an ultrasound finding of a non-viable pregnancy in an asymptomatic patient), 13 (26%) were incomplete miscarriages, and five (10%) were complete miscarriages. All cases were haemodynamically stable. Only seven (14%) cases were managed medically (200 μg misoprostol four times sublingually without repetition). 43 (86%) cases were treated surgically. Of these, two (4%) cases were treated without prior medical management because of acute presentation with bleeding, and 41 (82%) cases were treated after failure of medical management, when expulsion of conception products did not occur after the full dose of medical management regimen. 43 (86%) women received antibiotic prophylaxis after surgery without specific indication, which is not recommended. Seven (14%) women received no antibiotics, whereas others received a variety of different antibiotic regimens. Expectant management did not require admission, and these cases were not recorded in this audit.

INTERPRETATION

This audit showed a high percentage of failure in the medical management regimen and poor adherence to antibiotic prophylaxis guidelines in surgical management. Furthermore, all patients not presenting with acute bleeding were treated with medical management first, without an opportunity to choose surgical management. To improve outcomes of medical management and offer patients a real choice of management methods, clear local guidelines need to be developed with an evidence-based medical management regimen (the ACOG regimen reports an expulsion rate of up to 84%). Regular audit and team feedback could further improve guideline adherence also in the use of antibiotic prophylaxis.

FUNDING

None.

Immunological control of hepatotoxicity and parasite egg excretion in Schistosoma mansoni infections: stage specificity of the reactivity of immune serum in T-cell deprived mice

Within seven weeks of infection with 200 Schistosoma mansoni cercariae, T-cell deprived mice have been shown to suffer from extensive microvesicular damage to hepatocytes, and an inability to excrete parasite eggs at the same rate as comparably infected, immunologically intact controls. Administration of serum (CIS) from chronically infected, immunologically intact donors prevented the development of microvesicular cell damage and partially restored egg excretion rates in infected deprived mice. Serum pools obtained from mice injected either with intact S. mansoni eggs or with a homogenate of eggs emulsified in Freund's complete adjuvant (FCA) were as effective as CIS in preventing hepatotoxicity and restoring the rate of egg excretion in infected deprived recipients. The degree of protection of liver tissue afforded by immune sera could be monitored either by histopathological examination of liver sections or by estimation of serum transaminase concentrations, the results from both assays being generally in agreement. Sera from donor mice injected with cercarial or worm antigens in FCA were relatively inactive either in protecting against S. mansoni-induced liver damage or in reconstituting egg excretion rates in infected deprived mice. Serum from donor mice infected with 25 cercariae became hepato-protective between 49 and 53 days after infection of the donors, and the degree of hepatoprotective activity and egg excretion reconstituting capacity in the serum of 25 cercariae-infected donors was shown to increase between 8 and 16 weeks after infection. Increasing the size of infection of the serum donors to 100 cercariae gave only a marginal increase of hepatoprotective activity at 7 weeks when compared with serum donors infected with 25 cercariae for 7 weeks. Liver parenchymal cells of very heavily infected, immunologically intact mice were found to show microvesicular damage similar to that in livers of infected deprived mice, and administration of CIS to these normal mice was histopathologically protective. However, the elevated serum transaminase concentrations obtaining in the infected normal mice were not reduced to any extent by CIS. The results obtained from serum-reconstituted deprived mice are discussed in terms of the contribution they may make to a better understanding of the host-parasite relationship in immunologically intact mice.

Serum protein concentrations during Schistosoma mansoni infection in intact and T-cell deprived mice. II. Immunoglobulin G and antibodies specific for heterologous erythrocytes

Mice infected with from twenty to fifty Schistosoma mansoni cercariae were found to have elevated serum IgG concentrations following patency of the infection, and the parasite-induced increase in concentration of IgG was dependent on the possession by the host of an intact T-cell lymphocyte pool. Following passive transfer of hyperimmune anti-sheep erythrocyte (SRBC) antibody, there was a more rapid decrease of haemolytic and haemagglutinating antibody titres in S. mansoni-infected, immunologically intact recipients than in uninfected intact mice, and infected or uninfected T-cell deprived mice. However, primary and secondary active immunization with SRBC resulted in similar patterns of serum antibody titre increase and decay in infected and uninfected intact mice over a time course of 140 days. The number of direct and indirect haemolytic plaque-forming (PFC) cells per million spleen cells was similar in S. mansoni-infected and uninfected immunologically intact mice 6 days after either primary or secondary challenge with SRBC. It is concluded that S. mansoni-infected immunologically intact mice challenged with heterologous erythrocytes synthesize anti-erythrocyte antibody at a greater rate than similarly challenged, uninfected mice.

Serum protein concentrations during Schistosoma mansoni infection in intact and T-cell deprived mice. I. The acute phase proteins, C3 and serum amyloid P-component (SAP)

Normal mice developed marked elevation of two acute phase plasma proteins, C3 and serum amyloid P-component (SAP), between 40 and 50 days after percutaneous infection with cercariae of Schistosoma mansoni. The high levels persisted until the end of the experiment (day 106). The onset of this acute phase response corresponds with the reported time at which granulomata develop in the liver. In mice deprived of T cells by thymectomy and anti-thymocyte serum, the granulomata were significantly smaller and all the animals died between days 70 and 80. These mice had normal C3 levels throughout although there was a rise in SAP concentration. C3 and SAP levels in infected control mice, which had been thymectomized but not deprived of T cells with anti-thymocyte serum, were the same as in intact infected animals. The different behaviour of C3 and SAP in infected T-cell deprived mice may reflect the alteration in specific schistosomal pathology and/or a role for T cells in mediation of the acute phase production of some proteins.

The pathological effects of immunosuppression of Schistosoma mansoni-infected mice, with particular reference to survival and hepatotoxicity after thymectomy and treatment with antithymocyte serum, and treatment with hydrocortisone acetate

The effects of various immunosuppressive regimes on the survival and liver pathology of mice infected with Schistosoma mansoni were investigated. T-cell deprivation before infection (by adult thymectomy and subsequent anti-thymocyte serum administration), or treatment with hydrocortisone or cyclophosphamide or azathioprine after infection, all reduced survival of infected mice when compared with immunologically intact, infected mice. T-cell deprivation or steroids produced severe liver damage in infected mice despite a reduction in the size of the peri-oval granulomatous inflammatory reaction. Administration of chronic infection serum reduced liver damage in both T-cell-deprived and steroid-treated animals, but improved survival only in the deprived animals and not to the level seen in normal infected mice. The liver damage in immunosuppressed mice was not due to opportunistic bacterial infection. Thus, although immunosuppression reduced the granulomatous response to schistosome eggs in the livers of infected mice (as it does to eggs injected intravenously into the lungs), survival time was decreased. The relevance of these findings to human S. mansoni infections is discussed.

Restricted heterogeneity of antibody synthesized by T-cell deprived mice

Mice which had been thymectomized and injected with anti-thymocyte serum to remove long-lived recirculating T cells, initially failed to produce haemagglutinating and haemolysing antibody after injection of sheep erythrocytes. After six fortnightly injections of heterologous erythrocytes, however, haemolysin titres in the T-cell deprived mice were comparable to those in similarly challenged but immunologically intact animals. Isoelectric focusing of these sera indicated that the anti-sheep erythrocyte antibody eventually synthesized by the T-cell deprived mice was less heterogeneous than antibodies found in the sera of control mice.

Schistosoma mansoni infections in T-cell deprived mice, and the ameliorating effect of administering homologous chronic infection serum. II. Pathology

Liver changes occurring in mice deprived of their T-cells by a combination of thymectomy and anti-mouse thymocyte serum, and in immunologically intact control mice, were followed during the early stages of heavy Schistosoma mansoni infections. Lesions in both groups began developing by day 38 and were maximal by day 48. Hepatic changes in control mice culminated in large hypersensitivity granulomas, tissue eosinophilia, portal periphlebitis, fibrosis, vascular obstruction, and infarction leading to arterialization and preferential sinusoidal channeling. Deprived mice showed greatly reduced egg reactions composed principally of macrophages, monocytes, and occasional neutrophils, and only minimal alteration of liver architecture; however, focal and disseminated hepatocellular lesions became prominent as the infections progressed, and by day 48 virtually every hepatocyte was affected. Typically, hepatocytes showed microvesicular cytoplasmic damage (steatosis) or ballooning degeneration with accompanying nuclear pyknosis or karyorrhexis. This cellular pathology may be attributed to the direct or indirect effect of eggs or egg products on liver cells. The administration of chronic infection serum obtained from immunocompetent mice to T-cell deprived mice dramatically eliminated the hepatocellular lesions. It also increased eosinophil participation and fibrosis in the egg reactions but did not restore the size and other cellular features typical of egg hypersensitivity granulomas. Serum from uninfected normal mice was found to lack these effects.

Studies on the host-parasite relationship in Schistosoma mansoni-infected mice: the immunological dependence of parasite egg excretion

CBA mice deprived of their T cells by means of thymectomy and anti-thymocyte serum and subsequently infected with Schistosoma mansoni were found to have substantially fewer parasite eggs in their faeces than similarly infected immunologically-intact control animals. The number of parasite eggs deposited in the tissues of T-cell deprived mice was by comparison only marginally lower than in control mice. Administration of serum obtained from normal mice with chronic S. mansoni infections partially restored the egg excretion rate in infected deprived mice, and also resulted in an increased number of eggs being deposited in the liver and intestine of these animals.