Hepatitis B virus reactivation in cancer patients receiving direct-acting antivirals for hepatitis C virus infection

Direct-acting antivirals (DAAs) against hepatitis C virus (HCV) infection can cause hepatitis B virus (HBV) reactivation in HBV/HCV co-infected patients. Cancer patients undergoing immunosuppressant treatment or chemotherapy are at risk for HBV reactivation. To our knowledge, no prospective studies have examined the risk of HBV reactivation during DAA treatment for HCV infection in cancer patients with HBV/HCV co-infection. Here, we report the results of one such study. In a prospective observational study, we enrolled HCV-infected cancer patients undergoing DAA treatment at The University of Texas MD Anderson Cancer Center between January 2015 and March 2018. Data regarding demographics, cancer history, and prior HCV treatment history were collected. Patients were assessed for HBV status before DAA treatment and for HBV-related outcomes, including HBV reactivation, hepatitis flare, and HBV-associated hepatitis, during DAA treatment. Demographic and treatment variables were analyzed using descriptive statistics. One hundred sixty-six patients were analyzed. Forty-eight patients received systemic chemotherapy within 6 months before to 6 months after treatment with DAAs. Ledipasvir plus sofosbuvir was the most common DAA regimen, administered to 88 patients (53%). Fifty-one patients (31%) had past HBV infection, and 4 (2.4%) had chronic HBV infection. No patient experienced HBV reactivation, hepatitis flare, or HBV-associated hepatitis induced by DAA treatment. In HCV-infected cancer patients, DAA treatment is safe regardless of whether patients have past or chronic HBV infection. However, HBV screening is still recommended before the initiation of and during DAA treatment, as is anti-HBV prophylactic treatment in selected cases.

Strongyloides stercoralis Infection in Solid Organ Transplant Patients Is Associated With Eosinophil Activation and Intestinal Inflammation: A Cross-sectional Study

BACKGROUND

Strongyloidiasis can cause devastating morbidity and death in immunosuppressed patients. Identification of reliable biomarkers for strongyloidiasis in immunosuppressed patients is critical for the prevention of severe disease.

METHODS

In this cross-sectional study of solid organ transplant (SOT) candidates and recipients, we quantified Strongyloides-specific IgG to the recombinant NIE-Strongyloides antigen and/or to a soluble extract of S. stercoralis somatic antigens ("crude antigen") using enzyme-linked immunosorbent assays (ELISAs). We also measured peripheral eosinophilia, 4 different eosinophil granule proteins, and intestinal fatty acid-binding protein (IFABP).

RESULTS

We evaluated serum biomarkers in 149 individuals; 77 (52%) pre-SOT and 72 (48%) post-SOT. Four percent (6/149) tested positive by NIE ELISA and 9.6% (11/114) by crude antigen ELISA (overall seropositivity of 9.4% [14/149]). Seropositive patients had higher absolute eosinophil counts (AECs) than seronegative patients (P = .004). AEC was positively correlated to the levels of eosinophil granule proteins eosinophil cationic protein (ECP) and eosinophil peroxidase (EPO) (P < .05), while IFABP was positively related to the 2 other eosinophil granule proteins (major basic protein [MBP] and eosinophil-derived neurotoxin [EDN]; Spearman's r = 0.3090 and 0.3778, respectively; P < .05; multivariate analyses slopes = 0.70 and 2.83, respectively).

CONCLUSIONS

This study suggests that, in SOT patients, strongyloidiasis triggers both eosinophilia and eosinophil activation, the latter being associated with intestinal inflammation. These data provide insight into the pathogenesis of S. stercoralis infection in the immunocompromised population at high risk of severe strongyloidiasis syndromes.

547. A Retrospective Cohort Study of Treatment Patterns and Clinical Outcomes in Patients with COVID-19

Background

The SARS-CoV-2 pandemic has caused over 400,000 deaths worldwide thus far, and poses therapeutic challenges for millions of patients. There is currently no treatment for SARS-CoV-2 infection approved by the United States Food and Drug Administration. Multiple agents have been used off-label to treat SARS-CoV-2 infection based on small observational cohorts and in vitro data. Here we present the experience of a large academic medical center in treating SARS-CoV-2 infection.

Methods

We performed a retrospective cohort study of patients admitted for greater than 24 hours with a nasopharyngeal, oropharyngeal, and/or bronchoalveolar lavage sample positive for SARS-CoV-2 by polymerase chain reaction (PCR). Demographic data, comorbidities, clinical data, and treatment data were collected from the electronic medical record. Off-label therapies were used at the discretion of the treating providers guided by regularly updated treatment guidelines assembled by infectious diseases physicians and antimicrobial stewardship pharmacists. The primary outcome assessed was in-hospital mortality. Secondary outcomes included admission to the intensive care unit (ICU), endotracheal intubation, initiation of vasopressors, and drug-related adverse events.

Results

Data collection was completed for 448 patients admitted between March 18, 2020 and May 8, 2020. All-cause in-hospital mortality was 13.4% (60/448) during this time. Mortality rates increased with age, up to 45% for patients over 80 years old. Male sex, hypertension, chronic pulmonary disease, end-stage renal disease, chronic liver disease were also risk factors for increased mortality. QTc interval prolongation occurred significantly more frequently in patients who received hydroxychloroquine (HCQ) with or without azithromycin(AZM) than those who did not (HCQ 6%, HCQ+AZM 7.8% vs all other patients, 0%, p< .0001). Review of treatment trends showed close adherence to the treatment recommendations at that time (Figure 1).

Patient Characteristics

Admission Laboratory Data by Disease Severity

QTc Prolongation

Conclusion

SARS-CoV-2 infection is associated with significant inpatient mortality, and use of off-label treatments was associated with significant drug-related adverse events. Treatment regimens changed rapidly, and providers adhered closely to institutional guidelines as they evolved.

Treatment Trends by Week

QTC pre/post Treatment by Hydroxychloroquine Use vs. No Hydroxychloroquine Use

Disclosures

Samir Gupta, MD, Gilead Sciences (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member)ViiV (Consultant, Grant/Research Support, Scientific Research Study Investigator, Advisor or Review Panel member, Research Grant or Support)

Salvage therapy in cancer patients with hepatitis C without sustained virologic response after direct-acting antivirals-A prospective study

Background and Aim

No information exists regarding direct‐acting antivirals (DAAs) salvage therapy for Hepatitis C (HCV)‐infected patients with any type of cancer. We prospectively evaluated the safety and efficacy (SVR12) of salvage therapy in these patients.

Methods

Patients who failed initial DAAs (01/2015–01/2018) were analyzed. Resistance‐associated substitutions to NS5A and NS3 were investigated by population sequencing.

Results

Of 164 patients enrolled, 16 (10%) experienced treatment failure. Of these, 11 patients received salvage therapy. The majority (91%) were men; 55% had genotype 1a, 45% had cirrhosis, and 45% had hepatocellular carcinoma. Four patients failed the first salvage therapy, and two of them required a second salvage therapy. Overall, 9 of 11 (82%) patients achieved SVR12. All four patients treated with sofosbuvir/velpatasvir/voxilaprevir (+/− ribavirin) achieved SVR12. The presence of resistance‐associated substitutions did not impact response. Seven patients developed grade 1/2 adverse events. No patient had grade 3/4 adverse events. No patient required interruption of DAA therapy because of clinical or laboratory abnormalities.

Conclusions

This is the first prospective study in HCV‐infected cancer patients failing DAAs. The efficacy of salvage therapy in this group appears to be lower than previously reported in non‐cancer patients, but better response rates are observed with newer regimens. Salvage therapy is associated with minimal toxicity.

2197. Hepatitis B Reactivation in Patients with Malignancies Undergoing Treatment for Hepatitis C Infection with Direct-Acting Antivirals

Background

Reactivation of hepatitis B virus (HBV) can occur in patients after cancer therapies. Direct-acting antivirals (DAAs) are the effective therapies for hepatitis C virus (HCV) infection, and HBV reactivation in HCV/HBV co-infected patients treated with DAAs has been reported. We analyzed the risk of HBV reactivation among HCV/HBV co-infected cancer patients being treated with DAAs.

Methods

We prospectively followed patients with any type of cancer and HCV treated with DAAs between January 2014 and January 2018 at MD Anderson Cancer Center. Information on demographics, use of radiation, chemotherapy, immunotherapy, or anti-CD20 antibodies, and anti-HBV therapy were collected. All patients had the following tests at baseline, 2 and 4 weeks after initiation of DAAs, at end of treatment (EOT), and 12 weeks after completion of DAAs: alanine aminotransferase, total bilirubin, HBV surface antigen (HBsAg), hepatitis B core antibody (anti-HBc), and HBV DNA and HCV RNA levels. We defined the following outcomes by AASLD-recommended parameters: HBV reactivation (HBsAg reverse seroconversion, HBV DNA >2 log compared with baseline, HBV DNA >3 log if HBV DNA was undetectable, or >4 log if baseline was unavailable), hepatitis flare (ALT increase ≥3 times baseline and >100 U/L), and HBV-associated hepatitis (HBV reactivation and hepatitis flare). Patients were followed for 12 weeks after completion of DAAs.

Results

Of 169 cancer patients treated for HCV infection, 2.4% (n = 4) had chronic HBV infection (HBsAg+/anti-HBc+), and most (3/4) of these were on anti-HBV therapy. Past HBV infection (HBsAg-/HBcAb+) was noted in 30% (51/166), and none received anti-HBV therapy. Of these, 37% (19/51) had cancer therapy within 6 months prior to DAA treatment. HBV reactivation did not occur in any co-infected patients. Two patients had hepatitis flare, but none developed HBV-associated hepatitis.

Conclusion

This is the first prospective study evaluating HBV reactivation in HCV/HBV co-infected cancer patients receiving DAAs. The risk of HBV reactivation in these patients seems to be low. Future studies with a larger cohort of co-infected cancer patients allowing personalized risk stratification are needed.

Disclosures

J. P. Hwang, Gilead Sciences: Investigator, Grant recipient; Merck & Co., Inc.: Investigator, Grant recipient. H. Torres, Gilead Sciences, Merck & Co., Inc.: Grant Investigator, Grant recipient; Vertex Pharmaceuticals: Grant Investigator, Grant recipient.

Underdeveloped embryos and germination in Aristolochia galeata seeds

Aristolochiaceae have been described as having seeds with underdeveloped embryos and morphological or morphophysiological dormancy. Aristolochia galeata is a native climber found in the Cerrado biome, associated with road and gallery forest edges. The aims of this study were to investigate: embryo growth rate, morphology and seed germination parameters under different treatments. Embryos were excised to obtain embryo length at four stages: initial, seeds after coat rupture, radicle tip protrusion and cotyledon emergence from the seed coat. Germination tests were conducted at 30 °C under three nitrate concentrations (1, 10 and 20 mM), fluctuating temperature (27/20 °C) and light and dark conditions. We found that seeds have underdeveloped embryos, which take about 301 ± 178 h (±SD) to achieve seed coat rupture, another 205 ± 126 h to reach radicle protrusion and 176 ± 76 h more to the final stage of cotyledon emergence. Germinability was above 52% in all treatments, except in the dark (15%). For all treatments, average germination time was above 290 ± 123 h. Potassium nitrate increased germinability to >87%. No particular treatment was required for embryo development, but seeds in the population that continued to germinate after 1 month were probably in various states of non-deep, simple morphophysiological dormancy. Increased germinability in nitrate treatments and light requirement for germination could prevent germination under unsuitable environmental conditions and be a strategy to increase seedling establishment in the cerrado.

A novel TC deletion resulting in Pro(260)-->Stop in the human LCAT gene is associated with a dominant effect on HDL-cholesterol

Human lecithin:cholesterol acyltransferase (LCAT) plays a key role in the biogenesis of circulating high-density lipoprotein-cholesterol (HDL-C) and reverse cholesterol efflux. We investigated the molecular defect in the LCAT gene in a family with low levels of HDL-C. The proband, a 53-year-old woman from Oklahoma City, had a HDL-C level of 0.21 mmol/l. The LCAT activity in the proband was 5 nmol/ml/h and cholesterol esterification rate was 54.2 nmol/ml/h, consistent with LCAT deficiency. Analysis of polymerase chain reaction (PCR) amplified subgenomic fragments of LCAT DNA on polyacrylamide gels revealed heteroduplex bands in the proband and three other affected individuals in exon 6. DNA sequence analyses of the proband's LCAT gene identified a 2 base pair deletion (TC) (base pairs 4544-4545, corresponding to amino acid 255) in the heteroduplex allele, thereby converting Pro(260) to a premature stop codon and a predicted truncated protein of 260 amino acids. This is approximately 60% of the length of the normal translated protein. The heterozygous individuals also revealed significant reduction in apolipoprotein A-1 levels compared with the unaffected family members (n=4). The marked reduction in HDL-C in the proband and sibling suggests a dominant effect of this mutation on HDL-C levels. Furthermore, because the deletion results in a heterozygous allele that can be detected by a simple PCR reaction and polyacrylamide gel-size fractionation, it may be possible to rapidly screen susceptible individuals for the presence of this mutation.

Apolipoprotein A-I(Zavalla) (Leu159-->Pro): HDL cholesterol deficiency in a kindred associated with premature coronary artery disease

We investigated the molecular defect causing high density lipoprotein cholesterol (HDL-C) deficiency in a male proband and his family members. Amplification and sequencing of genomic DNA disclosed a novel base-pair substitution at residue 159 in the apolipoprotein (apo) A-I gene. This substitution resulted in the loss of an AviII restriction site and a predicted substitution of leucine with proline at residue 159. Restriction enzyme analysis demonstrated absence of the AviII site in 19 of 40 biological family members. Compared with familial controls, subjects with the apoA-I(Zavalla) variant had reduced HDL-C (1.16 versus 0.27 mmol/L, P<0.0001), apoA-I (38.7 versus 124.4 mg/dL, P<0.0001), and apoA-II (14.3 versus 19.0 mg/dL, P<0.0001) levels. Two subjects who have developed coronary artery disease to date possess additional cardiovascular risk factors. Other heterozygotes for apoA-I(Zavalla) are presently without symptomatic coronary artery disease. This study identifies a monogenic cause of hypoalphalipoproteinemia, with the single base-pair substitution having a dominant effect on the low HDL-C phenotype. In addition, it extends recent observations that HDL-C deficiency states may be more prone to the development of premature coronary artery disease when accompanied by additional cardiovascular risk factors.

Familial defective apolipoprotein B-100 in hypercholesterolemic Chinese Canadians: identification of a unique haplotype of the apolipoprotein B-100 allele

Familial defective apo B-100 (FDB) is an autosomal dominant condition resulting in hypercholesterolemia. It is generally observed in 1-6% of hypercholesterolemic subjects in Caucasian populations studied. There are, thus far, no reports characterizing the frequency and phenotype of FDB in a Chinese population. We report on the frequency of the FDB (Arg(3500)--> Gln) mutation and the associated haplotype among 160 hypercholesterolemic (TC > or = 6.2 mmol/l) Chinese Canadians including 36 subjects with a clinical diagnosis of familial hypercholesterolemia (FH). Screening for the FDB mutation was done using a mutagenic polymerase chain reaction and haplotype analysis was undertaken using eight diallelic markers and the 3'HVR marker. One Chinese Canadian clinical FH heterozygote was positive for the FDB Arg(3500)--> Gln mutation while none of the remaining non-FH hypercholesterolemic subjects (n = 124) were carriers of this mutation. Haplotype analysis in the patient positive for this mutation revealed a unique haplotype which differed from both the common haplotype of this mutation observed in Caucasians and from the only other haplotype reported in a Chinese individual. The associated haplotype included a 9-base pair deletion in the signal peptide region and the presence of three restriction sites absent in previously reported haplotypes. These data suggest that the apo B-100 Arg(3500)--> Gln mutation does not appear to be a significant factor contributing to moderate hypercholesterolemia in a Chinese population residing in Canada. However, this mutation was rarely observed among Chinese individuals with a clinical diagnosis of FH. The presence among Chinese individuals of two different haplotypes associated with this mutation, which are different from what has been described among Caucasians is compatible with multiple recurrent origins for this mutation in the Chinese population.

Acute dyslipoproteinemia induced by interleukin-2: lecithin:cholesteryl acyltransferase, lipoprotein lipase, and hepatic lipase deficiencies

Recombinant human interleukin-2 (rIL-2) is used to treat refractory cancers. During such treatment, patients develop severe hypocholesterolemia along with striking alterations in the concentration and composition of the circulating lipoproteins. The present study was undertaken to gather information about the pathogenesis of these abnormalities. Patients were studied before-, during- and after a 5-day course of high dose i.v. rIL-2. Whole plasma cholesterol was markedly reduced by rIL-2 administration (52%; P < 0.001), whereas the triglyceride concentration did not change. Thus, the lipoproteins became triglyceride enriched (P = 0.004). Low density lipoprotein cholesterol, apolipoprotein B (apoB), high density lipoprotein cholesterol, and apoA-I concentrations all decreased. Esterified cholesterol levels were markedly reduced. Total plasma apoE increased markedly, and two kinds of abnormal particles appeared: 1) beta-migrating, very low density lipoproteins; and 2) discoidal, apoE- and phospholipid-containing particles with abnormal density and electrophoretic mobility. The activities of two lipoprotein triglyceride hydrolases, lipoprotein lipase and hepatic lipase, fell significantly during treatment and returned promptly to pretreatment levels after rIL-2 was discontinued. Lecithin:cholesteryl acyltransferase (LCAT) activity also decreased significantly (64%) during treatment, but in contrast to the lipases, remained low for at least 5 days after the last dose of rIL-2 (P < 0.001). High dose i.v. rIL-2 induces severe dyslipidemia with deficiencies of both postheparin lipases and acute LCAT deficiency. Most, if not all, of the lipoprotein changes observed are explained by the LCAT deficiency that follows IL-2-induced hepatocellular injury and cholestasis.

The molecular pathology of lecithin:cholesterol acyltransferase (LCAT) deficiency syndromes

Lecithin:cholesterol acyltransferase (LCAT) deficiency syndromes represent a group of rare genetic disorders of HDL metabolism that have been the subject of a large number of clinical, biochemical, and genetic studies. Of special interest are patients with LCAT-related disorders with severe HDL deficiency and the apparent absence of premature atherosclerosis. This finding is inconsistent with the general concept that low HDL cholesterol levels are an obligate risk factor for atherosclerosis. In this review, we describe 36 natural mutations in the LCAT gene that result in either familial LCAT deficiency (FLD) or the milder phenotype known as fish-eye disease (FED). We propose a new classification of the natural mutations of the LCAT gene that are described to date. The defects are divided into four classes based on both the clinical and biochemical characterization of the patient and data that were obtained from the functional assessment of the mutant proteins. We define FLD-associated mutations that underlie a complete or nearly complete loss of LCAT activity due to null mutations (Class 1), and missense mutations (Class 2), respectively. In addition, we distinguish two classes of FED-associated mutations (Classes 3, 4) that underlie a partial impairment of LCAT activity but differ in their lipoprotein substrate specificity. In addition, we review the evidence of atherosclerosis in subjects with LCAT deficiency syndromes. The observation that 6 (all males) of a total of 19 FED subjects suffered from premature CAD (as defined by < 55 years of age and < 60 years of age for women and men, respectively) challenges the earlier assumption that the FED phenotype is not associated with increased risk of CAD. However, premature CAD remains an unusual clinical complication in FLD subjects.

Markedly accelerated catabolism of apolipoprotein A-II (ApoA-II) and high density lipoproteins containing ApoA-II in classic lecithin: cholesterol acyltransferase deficiency and fish-eye disease

Classic (complete) lecithin:cholesterol acyltransferase (LCAT) deficiency and Fish-eye disease (partial LCAT deficiency) are genetic syndromes associated with markedly decreased plasma levels of high density lipoprotein (HDL) cholesterol but not with an increased risk of atherosclerotic cardiovascular disease. We investigated the metabolism of the HDL apolipoproteins (apo) apoA-I and apoA-II in a total of five patients with LCAT deficiency, one with classic LCAT deficiency and four with Fish-eye disease. Plasma levels of apoA-II were decreased to a proportionately greater extent (23% of normal) than apoA-I (30% of normal). In addition, plasma concentrations of HDL particles containing both apoA-I and apoA-II (LpA-I:A-II) were much lower (18% of normal) than those of particles containing only apoA-I (LpA-I) (51% of normal). The metabolic basis for the low levels of apoA-II and LpA-I:A-II was investigated in all five patients using both exogenous radiotracer and endogenous stable isotope labeling techniques. The mean plasma residence time of apoA-I was decreased at 2.08 +/- 0.27 d (controls 4.74 +/- 0.65 days); however, the residence time of apoA-II was even shorter at 1.66 +/- 0.24 d (controls 5.25 +/- 0.61 d). In addition, the catabolism of apoA-I in LpA-I:A-II was substantially faster than that of apoA-I in LpA-I. In summary, genetic syndromes of either complete or partial LCAT deficiency result in low levels of HDL through preferential hypercatabolism of apoA-II and HDL particles containing apoA-II. Because LpA-I has been proposed to be more protective than LpA-I:A-II against atherosclerosis, this selective effect on the metabolism of LpA-I:A-II may provide a potential explanation why patients with classic LCAT deficiency and Fish-eye disease are not at increased risk for premature atherosclerosis despite markedly decreased levels of HDL cholesterol and apoA-I.

The proton NMR of blood plasma and the test for cancer

The water-suppressed proton NMR spectra of plasma from healthy controls and cancer patients have been recorded along with the high-density lipoprotein (HDL) and triglyceride (TG) levels in the plasma. The dependence of the average of methylene and methyl resonance linewidths on the HDL/TG ratio is demonstrated. It is shown that the deranged lipoprotein levels caused by the presence of cancer lead to the serological test for cancer proposed by Fossel. The work provides the formation for a complete understanding of the proposed serological test for cancer. However, the wide variation in lipoprotein composition in the plasma from both healthy adults and cancer patients means that the serological test proposed by Fossel cannot be used as a screen for cancer.

Adaptation of aquatic microbial communities to pollutant stress

The importance of microbial adaptation in the removal of environmental pollutants and in maintaining active microbial communities in impacted ecosystems is discussed using the biodegradation of p-nitrophenol and the volatilization of mercuric mercury as examples. A molecular mechanism of adaptation is suggested by enrichment of mercury resistance (mer) genes in some communities upon exposure to mercury.

Study of the components of reverse cholesterol transport in lecithin:cholesterol acyltransferase deficiency

Enzymatic and lipid transfer reactions involved in reverse cholesterol transport were studied in healthy and lecithin:cholesterol acyltransferase (LCAT), deficient subjects. Fasting plasma samples obtained from each individual were labeled with [3H]cholesterol and subsequently fractionated by gel chromatography. The radioactivity patterns obtained corresponded to the elution volumes of the three major ultracentrifugally isolated lipoprotein classes (very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL)). In healthy subjects, the LCAT activity was consistently found in association with the higher molecular weight portion of HDL. Similar observations were made when exogenous purified LCAT was added to the LCAT-deficient plasma prior to chromatography. Incubation of the plasma samples at 37 degrees C resulted in significant reduction of unesterified cholesterol (FC) and an increase in esterified cholesterol (CE). Comparison of the data of FC and CE mass measurements of the lipoprotein fractions from normal and LCAT-deficient plasma indicates that: (i) In normal plasma, most of the FC for the LCAT reaction originates from LDL even when large amounts of FC are available from VLDL. (ii) The LCAT reaction takes place on the surface of HDL. (iii) The product of the LCAT reaction (CE) may be transferred to either VLDL or LDL although VLDL appears to be the preferred acceptor when present in sufficient amounts. (iv) CE transfer from HDL to lower density lipoproteins is at least partially impaired in LCAT-deficient patients. Additional studies using triglyceride-rich lipoproteins indicated that neither the capacity to accept CE from HDL nor the lower CE transfer activity were responsible for the decreased amount of CE transferred to VLDL and chylomicrons in LCAT-deficient plasma.

Interaction of high density lipoprotein with adipocytes in a new patient with Tangier disease

A 56-year-old man, the offspring of a consanguineous first cousin marriage, presented with clinical, morphological, and biochemical features of familial deficiency of high-density lipoproteins (Tangier disease). Of 8 first- and second-degree relatives examined, 4 had either plasma apo A-I or HDL cholesterol concentrations 2 standard deviations below normal population mean on at least 1 occasion. The patient and a majority of his relatives also had high plasma apo B concentrations relative to their levels of cholesterol. Adipose tissue biopsy was undertaken to study HDL interaction with the patients' cells. Specific uptake of HDL3 was demonstrated in adipocytes of this patient, but was decreased relative to a control of similar fat cell size. However, no marked difference in fat cell cholesterol content was observed between the Tangier patient and the control. Thus it appears unlikely that adipocytes play a role in the etiology of Tangier disease.

Serum antibodies in Campylobacter enteritis

A solid-phase enzyme immunoassay method for the measurement of total and class-specific serum antibodies to Campylobacter jejuni was developed. The test was found to be both sensitive and specific. Immunoglobulin M, G, and A antibodies were detected in about 90% of sera collected from patients recovering from Campylobacter enteritis, with the pattern of appearance and decline of these antibodies conforming to that usually seen in an acute infection. A poor antibody response was noted in patients with intermittent or prolonged enteritis. The clinical implications and diagnostic value of this test are discussed.

A study of the prevalence of rotavirus infection in children with gastroenteritis admitted to an infectious diseases hospital

In a 12 month survey of infants and children with gastroenteritis admitted to Fairfield Hospital, Melbourne, rotavirus was found in approximately 42% of patients. This virus was detected more often during the winter months, particularly in children aged between 12 months and 3 years. Detection of rotavirus by electron microscopy was found to be more sensitive than by counterimmunoelectrophoresis. Routine bacterial and viral studies revealed that bacterial pathogens and common enteric viruses were associated with relatively few cases of gastroenteritis. There is little doubt that rotavirus is the most important aetiological agent of acute gastroenteritis in yvirus is the most important aetiological agent of acute gastroenteritis in young children in Melbourne.

The effects of administering N-(2-benzoyloxyethyl) norfenfluramine to rats on the hepatic synthesis of glycerolipids

N-(2-Benzoyloxyethyl) norfenfluramine (S-780) was administered to rats by stomach tube at a dose of 50 mg kg-1 of body weight. Livers of the rats which were given an acute dose of the drug synthesized more triacylglycerol, phosphatidylcholine and phosphatidylethanolamine from [1,3-3H]glycerol and [14C]palmitate than did those of control rats. The measurements were made by injecting a mixture of the radioactive precursors into the portal veins of anaesthetized rats and freeze clamping a portion of the liver 1 min later. Diffferent results were obtained after treating rats daily with S-780 for 5 days. Liver slices from these rats synthesized less triacylglycerol and relatively more phosphatidylinositol plus phosphatidylserine from [3H]glycerol than did those of control rats. S-780 treatment depressed the hepatic synthesis of phosphatidylcholine and phosphatidylethanolamine as measured in vivo after intrapotal injection of [14C]palmitate and [3H]glycerol. Chronic treatment with S-780 also depressed food intake and lowered liver weight and body weight of rats fed the 41B diet. The results are discussed in relation to the effects of S-780 on the synthesis of glycerolipids.

The cellular basis of immunological recovery in nude mice after thymus grafting

The changes that take place in the peripheral lymphoid tissues of congenitally athymic nude mice after stimulation with Pneumococcus polysaccharide and after thymus grafting are described. We have found that after antigen stimulation there is an increase in the cellularity of the primary nodules and changes in the endothelial wall of the post-capillary venules suggestive of an increased cell traffic into the lymph nodes. No germinal centres were observed in nude mice subjected or not to deliberate antigen stimulation. After thymus grafting a slow infilling of the thymus-dependent areas by lymphocytes took place, in addition, the presence of germinal centres was noticed. A number of possible explanations for the findings described is put forward and discussed.

Haemopoietic stem cells and progenitors of functional T-lymphocytes in the bone marrow of 'nude' mice

The stem cell potential of thymusless nu/nu mice measured in terms of CFU ratio and the capacity to reprieve lethally irradiated mice was similar to that of nu/+ and CBA mice. The thymus of nu/nu→T6T6 rediation chimaeras was repopulated by donor cells. Proliferation of donor cells, presumed to be T-lymphocytes, was observed in regional lymph nodes 3 days after sensitization with oxazolone.

T6T6 thymus grafts implanted subcutaneously in nu/nu mice restored the response to C57BL skin grafts. The mitotic figures in the thymus implant 30 and more days after grafting were almost exclusively of host karyotype. The high proportion of host cells dividing in the lymph nodes of thymus-grafted nu/nu mice suggested that T-cells derived originally from nu/nu bone marrow were present. Allogeneic thymus grafts partially restored the response of nu/nu mice to oxazolone.

It is concluded that the failure of thymic development in nu/nu mice is not due to an absence of thymocyte precursors in the bone marrow or to anything in the general physiological environment which prevents their differentiation to thymocytes and T-lymphocytes. It is presumably the result of defective embryonic development of the epithelial rudiment.

Immune responses in congenitally thymus-less mice. II. Quantitative studies of serum immunoglobulins, the antibody response to sheep erythrocytes, and the effect of thymus allografting

The concentrations of immunoglobulins in the sera of congenitally thymus-less `nude' (nu/nu) mice of various ages were studied by single radial diffusion and compared with those in phenotypically normal nu/+ controls. γM was present in normal concentrations. γA and γG2a concentrations were greatly reduced. γG1 was normal at the time of weaning (28 days of age), but fell progressively thereafter until it was indetectable in most animals more than 60 days old. The primary response to 4 × 10⁷ sheep erythrocytes was studied by haemolytic plaque and serum haemagglutination techniques. Nu/nu mice made subnormal quantities of 19S and little or no 7S antibody. Subcutaneous grafting of neonatal CBA/H thymus at 10–25 days of age was followed by increased survival of nu/nu mice and by the appearance of normal concentrations of γG2a and γG1 globulins and near-normal concentrations of γA. Intraperitoneal injection of 10⁸ CBA/H thymus cells resulted in still higher concentrations of these three proteins. It is concluded that the establishment of normal serum concentrations of γA, γG2a and, especially, γG1 depends upon the presence of funtional T-lymphocytes. γM shows no such T-dependence.

Influence of cutaneous sensitization with oxazolone on recruitment of myelogenous stem cells in the thymus

Cutaneous sensitization of CBA mice with oxazolone was followed 3 days later by increased cell proliferation in the regional lymph nodes and spleen, as measured by incorporation of radiolabelled 5-iodo-2'-deoxyuridine. The thymus was reduced in weight and contained fewer proliferating cells. Other mice were part-body irradiated, with shielding of the anterior three-quarters of the body, and injected with CBA-T6T6 bone marrow cells. Half of them were subsequently sensitized with oxazolone. The frequency of dividing cells of bone marrow origin in the thymus of sensitized and control animals was estimated cytologically 3–70 days later. There was a significant tendency for sensitized mice to have more dividing cells of donor origin in the thymus than controls.

Immune responses in congenitally thymus-less mice. I. Absence of response to oxazolone

Cell proliferation in regional lymph nodes of mice sensitized with oxazolone was measured by uptake of ¹²⁵IUdR. Experimental factors affecting incorporation of IUdR into lymph nodes are described. The delayed hypersensitivity response was assessed by measuring the increase in ear thickness after subsequent challenge with oxazolone. Unlike normal mice, thymus-less `nude' mice showed no detectable response to oxazolone. Implantation of an allogeneic neonatal thymus, either subcutaneously or under the kidney capsule, adoptively conferred on `nude' mice the ability to mount a lymphoproliferative response.