Analysis of an adaptive lead weighted ResNet for multiclass classification of 12-lead ECGs

Background. Twelve lead ECGs are a core diagnostic tool for cardiovascular diseases. Here, we describe and analyse an ensemble deep neural network architecture to classify 24 cardiac abnormalities from 12 lead ECGs.Method. We proposed a squeeze and excite ResNet to automatically learn deep features from 12-lead ECGs, in order to identify 24 cardiac conditions. The deep features were augmented with age and gender features in the final fully connected layers. Output thresholds for each class were set using a constrained grid search. To determine why the model made incorrect predictions, two expert clinicians independently interpreted a random set of 100 misclassified ECGs concerning left axis deviation.Results. Using the bespoke weighted accuracy metric, we achieved a 5-fold cross-validation score of 0.684, and sensitivity and specificity of 0.758 and 0.969, respectively. We scored 0.520 on the full test data, and ranked 2nd out of 41 in the official challenge rankings. On a random set of misclassified ECGs, agreement between two clinicians and training labels was poor (clinician 1:κ= -0.057, clinician 2:κ= -0.159). In contrast, agreement between the clinicians was very high (κ= 0.92).Discussion. The proposed prediction model performed well on the validation and hidden test data in comparison to models trained on the same data. We also discovered considerable inconsistency in training labels, which is likely to hinder development of more accurate models.

Pre-existing chromatin accessibility and gene expression differences among naive CD4+ T cells influence effector potential

CD4+ T cells have a remarkable potential to differentiate into diverse effector lineages following activation. Here, we probe the heterogeneity present among naive CD4+ T cells before encountering their cognate antigen to ask whether their effector potential is modulated by pre-existing transcriptional and chromatin landscape differences. Single-cell RNA sequencing shows that key drivers of variability are genes involved in T cell receptor (TCR) signaling. Using CD5 expression as a readout of the strength of tonic TCR interactions with self-peptide MHC, and sorting on the ends of this self-reactivity spectrum, we find that pre-existing transcriptional differences among naive CD4+ T cells impact follicular helper T (TFH) cell versus non-TFH effector lineage choice. Moreover, our data implicate TCR signal strength during thymic development in establishing differences in naive CD4+ T cell chromatin landscapes that ultimately shape their effector potential.

Source contributions of surface ozone in China using an adjoint sensitivity analysis

Air pollution has become an adverse environmental problem in China, resulting in serious public health impacts. This study advanced and applied the CMAQ adjoint model to quantitatively assess the source-receptor relationships between surface ozone (O₃) changes over different receptor regions and precursor emissions across all locations in China. Five receptor regions were defined based on the administrative division, including northern China (NC), southern China (SC), Pearl River Delta region (PRD), Yangtz River Delta region (YRD), and Beijing-Tianjin-Hebei region (BTH). Our results identified the different influential pathways of atmospheric processes and emissions to O₃ pollution. We found that the atmospheric processes such as horizontal and vertical advection could offset the O₃ removal through chemical reactions in VOC-limited areas inside the receptor regions. In addition, O₃ pollution can be induced by transport of O₃ directly or its precursors. Our results of relative source contributions to O₃ show that transboundary O₃ pollution was significant in SC, NC and YRD, while the O₃ pollution in PRD and BTH were more contributed by local sources. Anhui, Hubei and Jiangsu provinces were the three largest source areas of NO_x and VOC emissions to O₃ in SC (>52%) and YRD (>69%). NO_x and VOC emissions from Tianjin and Beijing were the largest contributors to O₃ in NC (>34%) and BTH (>51%). PRD was the dominant source areas of NO_x (>89%) and VOC emissions (~98%) to its own regional O₃.

Comparison of magnetic resonance imaging–fluorodeoxy- glucose positron emission tomography fusion with pathological staging in rectal cancer

Background

This study represents an initial experience with combined magnetic resonance imaging (MRI) and [18F]fluorodeoxyglucose positron emission tomography (FDG PET) (MRI–PET fusion) in the primary staging of rectal carcinoma.

Methods

A retrospective analysis of data recorded on patients with rectal cancer was undertaken. Patients requiring long-course radiotherapy were excluded. Chest radiography, abdominal computed tomography and endorectal ultrasonography were performed. In addition, MRI of the pelvis, whole-body FDG PET and MRI–PET fusion were carried out. All patients subsequently underwent anterior resection.

Results

Twenty-three patients with rectal carcinoma (15 men), of median age 60 (range 46–75) years, were enrolled. In tumour (T) assessment, MRI correctly staged 14 of 22 T2/T3 tumours. In lymph node assessment, MRI–PET fusion had a sensitivity of 44 per cent, with a specificity and positive predictive value of 100 per cent. No additional information was acquired from MRI–PET fusion over MRI plus abdominal computed tomography and chest radiography.

Conclusion

MRI–PET fusion adds little to conventional investigations for staging rectal carcinoma.

Ultrasonography of the hand and wrist

Musculoskeletal ultrasonography (US) of the hands and wrist has recently been increasing in popularity. Recent rapid technical advances in the US, such as new ultra-high frequency probes and smaller probe sizes, have led to improved image quality. This, in turn, has accelerated the growth of musculoskeletal US. Known advantages of US are its lack of ionising radiation, noninvasiveness, portability and low cost. Dynamic and real-time assessment and Doppler imaging are additional benefits of this modality, especially in the imaging of the hands and wrist. Superficial structures of the hands and wrist, including the tendons, ligaments, nerves and vessels, are amenable to imaging with high frequency US. In this article, we demonstrate a spectrum of hand and wrist pathology using US, including entrapment neuropathy, inflammatory conditions, traumatic injury and masses. Ultrasound-guided procedures applicable to the hand and wrist are also briefly discussed.

Erdheim-Chester disease: a rare cause of acute renal failure

Erdheim-Chester disease (ECD) is a rare systemic histiocytic infiltrative disease of unknown aetiology. In radiology it is characterized by symmetrical sclerotic bone lesions predominantly affecting the diaphyses and metaphyses of long bones. Perivascular fibrosis has been reported in the literature as being a feature of this disease and we report one such case that presented with an encased aorta and renal arteries leading to acute renal failure. The diagnosis of ECD was delayed until a biopsy of the retroperitoneal infiltrate was performed. Further imaging with fluorine 18 deoxyglucose positron emission tomography, bone scintigraphy, plain films of the long bones and CT of the chest, abdomen and pelvis were performed to assess the extent of the patient's systemic disease involvement. To our knowledge, this is the first reported case of ECD presenting with acute renal failure secondary to bilateral occlusion of the renal arteries.

Incidental finding of meningioma on bone scintigraphy

An incidental finding of an intracranial posterior fossa meningioma detected by bone scintigraphy is presented. Most of the published literature on the diagnosis of meningioma is on the use of CT and MRI. There is limited published literature on the detection of meningioma with bone scintigraphy.

Management of a Class II deep bite malocclusion with combined straightwire appliance and bioprogressive therapy

Development of straightwire appliances and improvement in archwire technology have simplified fixed appliance therapy in orthodontics. Although straightwire appliances are routinely used to treat most malocclusions, there are inherent limitations and it is necessary to look at the needs of each individual case rather than to simply proceed through a "cookbook" series of archwires to achieve a desired result. The Bioprogressive Therapy, although biomechanically complex, offers several advantages that can be integrated with the straightwire appliances to overcome the latter's shortcomings. This article illustrates the use of simplified Bioprogressive mechanics by means of utility arch in the treatment of a Class II deep bite malocclusion with high anchorage requirement.

Development of a freshwater aquatic toxicity database for ambient water quality criteria for methyl tertiary-butyl ether

The detection of methyl tertiary-butyl ether (MTBE) in groundwater and surface water in recent years has drawn attention to its potential effects in aquatic ecosystems. To address concerns regarding MTBE environmental effects and to establish safe concentrations in surface waters, a collaborative effort was initiated in 1997 to develop aquatic toxicity databases sufficient to derive ambient water quality criteria for MTBE consistent with United States Environmental Protection Agency (U.S. EPA) requirements. Acute toxicity data for six species, chronic toxicity data for a fish and an invertebrate, and plant toxicity data were developed in order to complete the freshwater database. The toxicity tests followed U.S. EPA and American Society for Testing and Materials (ASTM, Philadelphia, PA, USA) procedures and were conducted in accordance with U.S. EPA Good Laboratory Practice guidelines. Based on measured exposure concentrations, acute toxicity endpoints ranged from 472 to 1742 mg MTBE/L, while chronic endpoints (IC25) were 57 to 308 mg MTBE/L. Aquatic invertebrates were generally more sensitive than fish to MTBE in both acute and chronic exposures. Acute-to-chronic ratios for fathead minnows and Daphnia magna were 3.4 and 11.3, respectively. The measured acute and chronic toxicity were within a 10-fold factor of toxicity predicted from quantitative structure-activity relationships for baseline toxicity or nonpolar narcosis typical of ether compounds. The data developed in this study were consistent with existing data and showed that MTBE has low acute and chronic toxicity to freshwater organisms. Reported environmental concentrations of MTBE are several orders of magnitude lower than concentrations observed to cause effects in freshwater organisms.

Insulin-like growth factor-I and transferrin mediate growth and survival of Chinese hamster ovary cells

The aim of this investigation was to elucidate the roles of insulin-like growth factor-I (IGF-I) and transferrin in the survival and proliferation of Chinese hamster ovary (CHO) cells upon withdrawal of serum. For this purpose, we employed DNA analysis and flow cytometry to compare CHO cell lines expressing either IGF-I alone or IGF-I and transferrin. The ability of cells to cycle and the occurrence of apoptosis were monitored in these cells in serum-free medium. These results indicate that IGF-I alone is able to maintain the viability of CHO cells for an extended length of time in the absence of serum. Transferrin alone does not promote survival or proliferation. Only in the presence of both IGF-I and transferrin do cells survive and proliferate. Therefore, in attached CHO cultures, IGF-I alone does not stimulate cell proliferation but is a requirement for growth in serum-free medium in cooperation with transferrin. We report on the dual role of IGF-I as a survival factor in CHO cells and its interlocking role with transferrin to stimulate cell growth.

Diuretic renography with the addition of quantitative gravity-assisted drainage in infants and children

The aim of this study was to evaluate the use of quantitative gravity-assisted drainage (GAD) using >50% residual activity as an indicator to confirm obstruction in diuretic renography in the investigation of hydronephrosis and hydroureteronephrosis in infants and children. This was evaluated in 2 groups: furosemide clearance half-time (t 1/2) > 20 min (obstructed range) and t 1/2 = 10-20 min (indeterminate range).

METHODS

Two hundred children (155 boys, 45 girls; age range, 2 d to 16 y; median age, 26 wk) were studied over a 2-y period. One hundred thirty-five F+20 (diuretic given 20 min after radiopharmaceutical) and 65 F+0 (simultaneous administration of diuretic and radiopharmaceutical) studies were performed with intravenous administration of 99mTc-mercaptoacetyltriglycine (MAG3) and furosemide. At the end of the 20-min diuretic phase, a 5-min post-GAD image was obtained, and the percentage of residual activity was calculated by comparison with the last 5 min of the diuretic phase. All patients were monitored for 6-12 mo, and the final diagnoses were based on either surgical findings or conservative management with follow-up sonography or 99mTc-MAG3 studies. Results of the diuretic renography using quantitative GAD were then compared with the final diagnoses.

RESULTS

A renal unit was defined as a kidney and its ureter. In the 200 patients studied, 256 hydronephrotic renal units were analyzed: 10 units showed no function, 1 unit showed poor function, 131 units had t 1/2 < 10 min, 62 units had t 1/2 > 20 min, and 52 units had t 1/2 = 10-20 min. Of the 131 renal units with t 1/2 < 10 min, there was only 1 case of obstruction. Using GAD > 50% residual activity for the diagnosis of obstruction in 62 renal units with t 1/2 > 20 min, the sensitivity was 88.4%, the specificity was 73.7%, and the accuracy was 83.9%. Similarly, using GAD > 50% residual activity for the diagnosis of obstruction in 52 units with t 1/2 = 10-20 min, the sensitivity was 100%, the specificity was 79.5%, and the accuracy was 82.7%.

CONCLUSION

The quantitation of GAD > 50% residual activity in diuretic renography can help to differentiate between obstruction and nonobstruction in renal units with t 1/2 > 20 min and t 1/2 = 10-20 min. The quantitation of GAD when t 1/2 < 10 min is not useful because obstruction has already been excluded.

Inguino-scrotal hernia detection in the early phase of a bone scan

A case report of a large inguino-scrotal hernia detected in the early phase of a radionuclide bone scan is presented.

F+0 diuresis renography in infants and children

The purpose of this study was to evaluate the feasibility of modifying diuresis renography by the simultaneous administration of 99mTc-mercaptoacetyltriglycine (MAG3) and furosemide in the investigation of hydronephrosis and hydroureteronephrosis in infants and children. Two parameters were assessed: the diuretic response in normal kidneys and the ability of the F+0 study to differentiate between renal obstruction and nonobstruction and to identify the level of obstruction in cases of renal obstruction.

METHODS

Seventy-two patients (48 males, 24 females; age 2 d to 7 y; median age 6 wk) with sonographic diagnoses of hydronephrosis or hydroureteronephrosis were reviewed prospectively over a 3-y period. All patients had prior sonographic studies and micturating cystourethrography. Bladder catheterization was not routinely performed and was undertaken only if the child had suspected vesicoureteric junction (VUJ) obstruction or grade II or more vesicoureteric reflux. A weight-adjusted dose of 99mTc-MAG3 (maximum 200 MBq, minimum 20 MBq) and 1 mg/kg of furosemide (maximum 40 mg) were administered intravenously at the same time. Posterior imaging of the kidneys and bladder was performed for 20 min and followed by gravity-assisted drainage or imaging after voiding. All patients were followed-up for 6-12 mo, and the final diagnoses were based on either surgery or conservative management with repeated sonography or follow-up 99mTc-MAG3 studies (or both). The results of the F+0 diuresis renography were then compared with the final diagnoses.

RESULTS

A renal unit was defined as a kidney and its ureter. There were 151 renal units with 1 patient having bilateral duplex kidneys, 6 patients having unilateral duplex kidneys and 1 patient having a solitary kidney. Fifty-five normal renal units and 96 abnormal renal units on the basis of sonographic findings were assessed. The furosemide clearance half-time for the 55 normal renal units was 1.3-6.3 min (mean 3.8 min). Of the 96 abnormal renal units, 53 were classified as nonobstructed and 43 were classified as obstructed. Of the 53 renal units classified as nonobstructed, there were 48 true-negative studies and 5 false-negative studies; of the 43 renal units classified as obstructed, there were 40 true-positive studies and 3 false-positive studies. The sensitivity was 88.9%, specificity was 94.1% and accuracy was 91.7%. The level of obstruction, either pelviureteric junction or VUJ, was also correctly identified.

CONCLUSION

F+0 diuresis renography shows excellent diuretic responses in normal kidneys and is a valid method for the investigation of hydronephrosis and hydroureteronephrosis in infants and children.

Effects of a homologous series of linear alcohol ethoxylate surfactants on fathead minnow early life stages

Effects of a homologous series of three primarily linear alcohol ethoxylate surfactants were studied in laboratory flow-through 28-day early-life-stage tests with fathead minnow (Pimephales promelas Rafinesque). Surfactants were a C(9-11), C(12-13), and C(14-15) with an average of 6, 6.5, and 7 ethylene oxide units per mole of alcohol, respectively. Average measured surfactant recoveries were 103%, 81%, and 79% of nominal concentrations for the C(9-11) EO 6, C(12-13) EO 6.5, and C(14-15) EO 7 studies, respectively. Embryo survival at 48 h was not adversely affected at any of the concentrations tested. Impaired hatching and deformed fry were observed only in the C(12-13) EO 6.5 study. The 28-day LC50 values were 4.87, 2.39, and 1.02 mg/L for the C(9-11) EO 6, C(12-13) EO 6.5, and C(14-15) EO 7 surfactants, respectively. The corresponding NOECs for survival were 1.01, 1.76, and 0.74 mg/L. Posthatch fry growth was more sensitive than survival for the C(12-13) EO 6.5 and C(14-15) EO 7 surfactants. Survival of posthatch fry decreased with increasing surfactant alkyl chain length. Twenty-eight-day laboratory data were compared to 96-h laboratory, 10-day laboratory and 30-day stream mesocosm data for fathead minnow previously determined for these surfactants. Survival endpoints from the different exposures were comparable and only varied within a factor of two. Similarity of results suggests that it is possible to effectively use 96-h, 10-day, or 28-day laboratory data to predict environmental effects concentrations of these surfactants for fish. http://link.springer-ny. com/link/service/journals/00244/bibs/37n4p536.html</++ +HEA

Experimental transmission of hepatitis C virus-associated fulminant hepatitis to a chimpanzee

Hepatitis C virus (HCV) was transmitted from a patient with fulminant hepatitis C to a chimpanzee. The patient had developed two episodes of fulminant hepatitis C, each occurring after a separate liver transplantation. Serial serum and liver samples from the patient and the chimpanzee were analyzed for HCV replication, genotype, quasispecies heterogeneity, and antibodies. In the patient, the levels of HCV replication in serum and liver correlated with the degree of hepatocellular necrosis and the clinical expression of fulminant hepatitis. The same HCV strain, genotype 1a, was recovered from both episodes of fulminant hepatitis. An unusually severe acute hepatitis was also observed in the chimpanzee. The viruses recovered from the patient and the chimpanzee were almost identical and displayed relatively little quasispecies heterogeneity. Thus, the same HCV strain induced two episodes of fulminant hepatitis in a single patient and severe hepatitis in a chimpanzee, suggesting that the pathogenicity or virulence of a specific HCV strain may be important in the pathogenesis of fulminant hepatitis C.

Induction of estradiol-2-hydroxylase and ethoxyresorufin-O-deethylase by 3-substituted indole compounds

Estrogen can be hydroxylated at both 2- and 16alpha-positions. These two reactions are mutually exclusive. The 2-hydroxylated estrogen is relatively inactive compared with the 16alpha-derivative; hence, one approach in anti-estrogenic therapy is to look for drugs that can induce the 2-hydroxylation pathway. In the present study, using Balb/c and C57B/6 mice as the animal models, the induction effect of several isoprenyl compounds on estradiol-2-hydroxylase and ethoxyresorufin-O-deethylase activities was studied. The compounds examined included 2'- and 3'-methylbutadienyl-indoles and their respective acid condensation products, isopropyl indolocarbazole and yuehchukene; positional isomers of indole carbinols and carboxyaldehydes, as well as 3-methylcholanthrene, the prototype inducer of cytochrome P450 1A1. Our results demonstrated that while all of them were capable of inducing cytochrome P450 1A1-mediated ethoxyresorufin-O-deethylase activity, only the 3' isomers could induce estradiol-2-hydroxylase activity. The induction of these two activities did not show any direct correlation, suggesting that cytochrome P450 1A1 was not the same enzyme catalyzing both ethoxyresorufin-O-deethylation and estradiol-2-hydroxylation. Nevertheless, both inductions were mediated by the aryl hydrocarbon receptor. Among the compounds tested, yuehchukene showed competitive binding to estrogen receptor. This, together with the induction of estradiol-2-hydroxylase activity, may account for the anti-estrogenic effect of yuehchukene.

Experimental infection of chimpanzees with hepatitis C virus of genotype 5a: genetic analysis of the virus and generation of a standardized challenge pool

Six major genotypes (genotypes 1-6) of hepatitis C virus (HCV) have been identified. These genetic variants are being transmitted to chimpanzees, the only recognized animal model for the study of HCV. Genotype 5a (strain SA13), a variant found primarily in South Africa, has been transmitted to chimpanzees for the first time. Experimental infection of 2 chimpanzees was characterized by early appearance of viremia and peak virus titers of 10(5)-10(6) genome equivalents/mL. The HCV infection was resolved by week 15 after inoculation in 1 chimpanzee and persisted in the other. Both chimpanzees became anti-HCV-positive by week 14 after inoculation. Both chimpanzees developed viral hepatitis. The infectivity titer of a genotype 5a challenge pool prepared from the first passage of HCV in a chimpanzee was approximately 10(4) infectious doses/mL. Finally, sequence analysis of strain SA13 confirmed that genotype 5a is genetically distinct from other genotypes of HCV.

Infection of a chimpanzee with hepatitis C virus grown in cell culture

Culture supernatant harvested from Daudi cells, a lymphoplastoid cell line, after 58 days of infection with the H77 strain of hepatitis C virus (HCV), was inoculated into a chimpanzee. HCV RNA, as detected by RT-PCR, first appeared in the serum and liver 5 and 6 weeks, respectively, after inoculation. Peripheral blood mononuclear cells (PBMC) collected on week 7 were also positive for HCV RNA. The major sequences of hypervariable region 1 (HVR1) of the viral genome recovered from the inoculated chimpanzee were the ones which were the majority in the original H77 inoculum and not those which were in the majority in the culture supernatant. Only the sequence recovered from PBMC was the same as the major one found in the cell culture.

Reversible severe lower limb pain during a dipyridamole sestamibi myocardial perfusion study: a case report

A 68-year-old woman reported acute severe pain in both lower limbs during a dipyridamole sestamibi myocardial perfusion scan. The pain was rapidly relieved by the administration of intravenous aminophylline. A review of the literature on the adverse effects of dipyridamole did not include this symptom.

Intra-axial posterior fossa cryptococcosis: MRI findings

Two case reports of intra-axial posterior fossa cryptococcosis in immunocompetent patients are presented. Magnetic resonance findings of solitary abscesses with mildly irregular peripheral enhancement within the medulla, and irregular peripheral enhancement with a nodular component within the right cerebellum are described.

Sequence analysis of the hepatitis C virus genome recovered from serum, liver, and peripheral blood mononuclear cells of infected chimpanzees

Of 13 different strains of hepatitis C virus (HCV) in the inoculum used, only 1 persisted in human lymphocyte cell lines infected in vitro (N. Nakajima, M. Hijikata, H. Yoshikura, and Y. K. Shimizu, J. Virol. 70:3325-3329, 1996). To determine whether that particular strain (designated H1-2) has a tropism for lymphocytes in vivo, we sequenced hypervariable region 1 (HVR1) of the genome of HCV recovered from the sera, livers, and peripheral blood mononuclear cells (PBMC) of chimpanzees infected with plasma H77, the same inoculum used for the in vitro studies. In the PBMC collected from two chimpanzees during the early phase of infection, H1-2 was detected as the only or predominant HVR1 sequence. H1-2 was also detected in PBMC obtained during persistent infection from a chimpanzee that had been treated with immunosuppressants. From the livers of these chimpanzees, two to six different strains were recovered but H1-2 was not detected. Thus, H1-2 appeared to have an affinity for lymphocytes not only in vitro but also in vivo. In samples collected from a chimpanzee after 6 years of infection, however, such tissue compartmentalization of the HCV genome was not observed; a single strain became predominant in the serum, liver, and PBMC. An HCV strain capable of replicating in both the liver and PBMC probably emerged during in vivo replication and persisted.

Rheumatoid papules in a patient with acquired immune deficiency syndrome and symmetric polyarthritis

We describe a patient with acquired immunodeficiency syndrome (AIDS) and an unusual rheumatoid factor-positive symmetric inflammatory polyarthritis who met all 7 American College of Rheumatology criteria for RA, but who also had many features suggestive of seronegative inflammatory arthritis. Although cutaneous vasculitis has also been described in human immunodeficiency virus infection, this is the first report of cutaneous extravascular necrobiotic granuloma (rheumatoid papule) in AIDS. This case highlights the immunopathogenesis of inflammatory arthritis in AIDS and illustrates the difficulties in making a classic rheumatic diagnosis in the setting of the immune dysregulation caused by AIDS.

Ultrasound and computed tomography appearances of primary hepatic leiomyosarcoma

Primary hepatic leiomyosarcoma is a rare condition. The ultrasound and computed tomography findings in a 73 year old female patient are described. Previous reports have concentrated on the histopathological features and clinical presentation of the condition.

Infantile hepatic haemangioendothelioma

Three cases of infantile hepatic haemangioendotheliomas are described. Two demonstrate the natural history of regression of this benign tumour with no associated complication. The last case demonstrates life-threatening complications, which included cardiac failure, thrombocytopenia, disseminated intravascular coagulation and bleeding. Imaging modalities with plain films, ultrasound, computed tomography and angiograms are presented. Pathological findings in two of the cases are also described.

Efficacy of an inactivated hepatitis A vaccine in pre- and postexposure conditions in marmosets

A two-part challenge study was done in marmoset monkeys to confirm the efficacy of an inactivated hepatitis A vaccine. In part 1 (preexposure), 7 marmosets received a single low dose of vaccine (360 ELISA units [EL.U.]) and were challenged orally with wild type hepatitis A virus (HAV) either 1 or 6 months later. In part 2 (postexposure), 8 marmosets were challenged orally with HAV and then half each were inoculated with a single dose of 360 or 1440 EL.U. of vaccine 2 days later. The suboptimal immune response elicited by the low vaccine dose in the preexposure group was sufficient to induce complete protection against oral challenge with heterologous HAV in all marmosets that had responded serologically. In the postexposure group, the 360-EL.U. dose of vaccine resulted in partial protection against hepatitis A disease, whereas the 1440-EL.U. dose of vaccine elicited complete protection against disease and virus excretion.

[Ca2+]i inhibition of Ca2+ release-activated Ca2+ influx underlies agonist- and thapsigargin-induced [Ca2+]i oscillations in salivary acinar cells

Inhibition of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases by thapsigargin elicits [Ca2+]i oscillations in rat salivary gland (parotid) acinar cells which are similar to those activated by agonists but are nevertheless independent of inositol 1,4,5-trisphosphate (IP3) or IP3-sensitive Ca2+ stores (Foskett, J. K., Roifman, C. M., and Wong, D. (1991) J. Biol. Chem. 266, 2778-2782). Neither bafilomycin alone or together with monensin or chloroquine inhibited thapsigargin-induced [Ca2+]i oscillations, ruling out the involvement of vacuolar-type proton pumps or organellar acidity in the mechanisms underlying them. Acute inhibition of plasma membrane Ca(2+)-ATPase by 1 mM La3+ inhibited the decline of [Ca2+]i during the falling phase of the oscillation. Acute inhibition of plasma membrane Ca2+ influx by removal of extracellular Ca2+, membrane depolarization, or inorganic channel blockers immediately abolished oscillations, even when applied during the [Ca2+]i rising phase of the cycle. Ca2+ influx rate oscillated during [Ca2+]i oscillations, varying 1.5-13-fold during a cycle. Modification of the rate of Ca2+ influx, by titrating the extent of depletion of IP3-sensitive stores or manipulating extracellular [Ca2+], indicated that oscillations depended on a high rate of Ca2+ influx. In thapsigargin- or carbachol-treated cells which did not exhibit a sustained [Ca2+]i rise or [Ca2+]i oscillations, inhibition of Ca2+ influx activated plasma membrane Ca2+ permeability. Thus, agonist- and thapsigargin-induced [Ca2+]i oscillations in parotid acinar cells appear to be generated by plasma membrane-based mechanisms which involve periodic inactivation by [Ca2+]i of the Ca2+ release-activated Ca2+ influx pathway.

After-hours radiology

After-hours radiological procedures are essential but expensive in any major teaching hospital. Using the criteria that radiological procedures performed after-hours should have a reasonable probability of influencing or changing patient management acutely, a study of the justification of after-hours radiological procedures was performed at the Princess Alexandra Hospital. Computer print-outs were used to select the patients based on the dates and times of the procedures. Their charts were then reviewed. The study found that most after-hours radiological procedures were justified. However, it also identified certain procedures that need not be performed or at least could be reduced after-hours. The procedures were: (i) computed tomography (CT) head--epilepsy, meningitis; (ii) CT abdomen--trauma (intubated)--unable to examine abdomen; (iii) CT spine--obvious unstable fractures; (iv) Ultrasound abdomen--biliary colic (afebrile); and (v) Ultrasound kidneys--renal failure (afebrile).

Prevention of hepatitis C virus infection in chimpanzees after antibody-mediated in vitro neutralization

Hepatitis C virus (HCV) is the most important etiologic agent of non-A, non-B hepatitis and is a major cause of chronic liver disease and hepatocellular carcinoma. Development of an effective vaccine would be the most practical method for prevention of the infection, but whether infection with HCV elicits protective immunity in the host is unclear. Neutralization of HCV in vitro was attempted with plasma of a chronically infected patient, and the residual infectivity was evaluated by inoculation of eight seronegative chimpanzees. The source of HCV was plasma obtained from a patient during the acute phase of posttransfusion non-A, non-B hepatitis, which had previously been titered for infectivity in chimpanzees. Neutralization was achieved with plasma obtained from the same patient 2 yr after the onset of primary infection but not with plasma obtained 11 yr later, although both plasmas contained antibodies against nonstructural and structural (including envelope) HCV proteins. Analysis of sequential viral isolates from the same patient revealed significant genetic divergence as early as 2 yr after infection. However, the HCV recovered from the patient 2 yr after the infection had a striking sequence similarity with the HCV recovered from one of the chimpanzees inoculated with the acute-phase virus, suggesting that the progenitor of the new strain was already present 2 yr earlier. This evidence, together with the different sequences of HCV recovered from the chimpanzees that received the same inoculum, confirms that HCV is present in vivo as a quasispecies. These results provide experimental evidence in vivo that HCV infection elicits a neutralizing antibody response in humans but suggest that such antibodies are isolate-specific. This result raises concerns for the development of a broadly reactive vaccine against HCV.

Focal localization of the NHE-1 isoform of the Na+/H+ antiport: assessment of effects on intracellular pH

Na+/H+ exchange (antiport) is a major pathway for the regulation of intracellular pH. Antiport activity is stimulated when suspended cells adhere to the substratum. In this report, immunofluorescence was used to study the subcellular localization of the ubiquitous NHE-1 isoform of the antiport. NHE-1 was not distributed homogeneously on the surface of the cells. Instead, antiports were found to accumulate along the border of lamellipodia and near the edge of finer processes. Dual immunofluorescence experiments demonstrated that vinculin, talin and F-actin are concentrated at sites of NHE-1 accumulation. A mutated construct of NHE-1 lacking residues 566-635 of the cytosolic domain also accumulated near marginal lamellae. In contrast, the focal distribution observed in adherent cells was not detectable in cells grown in suspension. Fluorescence ratio imaging was used to define the functional consequences of focal accumulation of NHE-1. In the steady state, the pH was virtually identical throughout the cytosol. Moreover, no pH gradients were found to develop when cells recovered from an acid load by activation of Na+/H+ exchange. This is probably because of the presence of high concentrations of mobile buffers in the cytosol. The focal accumulation of antiporters near the cell margins may be involved in stimulation by adherence and/or generation of local osmotic gradients.

Markedly prolonged incubation period of hepatitis B in a chimpanzee passively immunized with a human monoclonal antibody to the a determinant of hepatitis B surface antigen

The protective efficacy of a human monoclonal antibody directed against the a determinant of hepatitis B virus (HBV) surface antigen was studied in a chimpanzee. A single high dose of 5 mg/kg (body weight) of monoclonal antibody SDZ OST 577 was intravenously administered to a chimpanzee, followed by intravenous challenge with 10(3.5) chimpanzee infectious doses of a wild-type HBV, the MS-2 strain (ayw subtype). The passively acquired antibody to HBV surface antigen could be detected for 40 weeks. Serum HBV DNA tested by a "nested" polymerase chain reaction assay was negative through the 36th week after virus challenge but became positive by the 38th week. The chimpanzee subsequently developed acute hepatitis B approximately 1 year after challenge. The nucleotide sequence of the a determinant of the surface gene of the replicated virus was identical with that of the inoculated wild-type virus. Thus, a human monoclonal antibody directed against the a determinant of HBV surface antigen delayed but did not prevent experimental infection of HBV and hepatitis in the chimpanzee. Our results indicate an incomplete ability of this antibody to protect against HBV infection in vivo after a single infusion.

Lack of protective immunity against reinfection with hepatitis C virus

Some individuals infected with hepatitis C virus (HCV) experience multiple episodes of acute hepatitis. It is unclear whether these episodes are due to reinfection with HCV or to reactivation of the original virus infection. Markers of viral replication and host immunity were studied in five chimpanzees sequentially inoculated over a period of 3 years with different HCV strains of proven infectivity. Each rechallenge of a convalescent chimpanzee with the same or a different HCV strain resulted in the reappearance of viremia, which was due to infection with the subsequent challenge virus. The evidence indicates that HCV infection does not elicit protective immunity against reinfection with homologous or heterologous strains, which raises concerns for the development of effective vaccines against HCV.

The natural history of infection with hepatitis C virus (HCV) in chimpanzees: comparison of serologic responses measured with first- and second-generation assays and relationship to HCV viremia

The sensitivity of first- and second-generation tests for antibody to hepatitis C virus (HCV) and the relationship among the patterns of antibody response and HCV viremia were examined in serial serum samples from 6 chimpanzees experimentally infected with HCV and followed less than or equal to 3 years. HCV infection was transient in 4 chimpanzees and became chronic in 2. All chimpanzees developed antibodies to HCV detectable by second-generation assays, while only 5 of the 6 became positive by first-generation assay. Second-generation were consistently more sensitive than first-generation assays for the early diagnosis of primary HCV infection. The pattern observed with second-generation assays was not influenced by the outcome of HCV infection, since antibodies remained persistently detectable throughout follow-up regardless of whether viremia was transient or persistent. In contrast, the first-generation antibody response was variable: It usually disappeared after loss of viremia, whereas its presence paralleled HCV viremia in chimpanzees with chronic infection.

Effect of Pili-Specific Antibodies on the Adherence of Haemophilus influenzae Type b to Human Buccal Cells

Different strains of Haemophilus influenzae type b (Hib) produce antigenically distinct pili that mediate adherence to human buccal epithelial cells. This study determined the ability of antibodies specific for the LKP3 pili of Haemophilus influenzae type b to inhibit the adherence of Hib strain Eagan (p+). Antiserum was prepared by immunization of rabbits with pili purified from Hib strain Eagan (p+). The presence of pili-specific antibodies in the immune serum was shown by selective immunoprecipitation of pilin and by electron microscopy of cells labeled with immunogold. Immune serum, affinity-purified antibody, and Fab fragments from immune serum significantly inhibited (P less than .001) adherence of strain Eagan (p+) to human buccal epithelial cells whereas preincubation with preimmune rabbit serum or Fab fragments from preimmune serum had no significant effect on adherence. Dilution of the immune serum, affinity-purified antibodies, or Fab fragments from immune serum resulted in decreased inhibition of Hib adherence. These results indicate that antibodies specific for LKP3 pili can effectively inhibit adherence of Hib strain Eagan (p+) and probably other strains that express this pilus serotype.

Early events in hepatitis C virus infection of chimpanzees

The cytoplasmic antigen and ultrastructural changes we described previously for chimpanzees (Pan troglodytes) infected with hepatitis C virus (HCV) or with hepatitis D virus have recently been shown to be indirect measures of viral replication and appear to represent a host response to the expression or action of interferon. The time of appearance of these changes in hepatocytes during HCV infection, when compared with similar changes in hepatitis D virus infection, suggests a very early replicative phase for HCV. To investigate the early events in HCV infection, we infected two chimpanzees with HCV and obtained blood and liver biopsy samples from them daily during the first 10 days of infection. The early stage of infection with regard to HCV replication, antigen expression, and ultrastructural changes was similar in both chimpanzees. When tested by cDNA/polymerase chain reaction, HCV sequences became detectable in the serum as early as 3 days after inoculation and remained positive through the peak of aminotransferase elevations. In one chimpanzee the peak of virus production appeared to be 7 weeks after inoculation, which was coincident with rising enzyme values. The cytoplasmic antigen, detected by immunofluorescence, and ultrastructural changes, detected by electron microscopy, became positive in hepatocytes 3 and 6 days, respectively, after HCV sequences were first detected in serum. Circulating anti-HCV appeared 13 weeks and 32 weeks after inoculation, respectively, in the chimpanzees. These data indicate a very early replicative phase for HCV and a potentially long period of infectivity before the appearance of anti-HCV.

Alteration of the catalytic efficiency of penicillin amidase from Escherichia coli

Ampicillin and cephalexin are beta-lactam antibiotics that are synthesized by the condensation of D-(-)-alpha-aminophenylacetic acid with 6-aminopenicillanic acid or 7-aminodeacetoxycephalosporanic acid, respectively. The rates at which the penicillin amidase of Escherichia coli catalyzes these reactions are too low to be of practical use. The objective of this study was to determine whether it is possible to alter the substrate specificity of penicillin amidase and select enzymes that efficiently hydrolyze substrates with alpha-aminophenylacetyl moieties at low pH, at which the alpha-amino group is nearly completely protonated. In this study, D-(-)-alpha-aminophenylacetyl-(L)-leucine (APAL) was used as a substrate analog of ampicillin and cephalexin. The gene for the penicillin amidase of E. coli ATCC 11105 was cloned and transferred to a leucine auxotroph of E. coli; numerous amidase mutants were selected by their ability to cleave APAL and provide leucine for growth in low-pH medium. The plasmid encoding one of the mutant amidases (pA135) was used to transform naive cells, and transformants that expressed the mutant amidase were shown to grow more rapidly in medium at pH 6.5 containing 0.1 mM APAL as the sole leucine source than did cells with the wild-type amidase. The mutant amidase was purified, and the second-order rate constant (kcat/Km) for APAL hydrolysis at pH 6.5 was found to be 10-fold greater than the rate observed with the wild-type enzyme. The difference between the rates of APAL hydrolysis by the mutant and wild-type amidases increased as the pH of the reactions decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Selection of amidases with novel substrate specificities from penicillin amidase of Escherichia coli

To obtain amidases with novel substrate specificity, the cloned gene for penicillin amidase of Escherichia coli ATCC 11105 was mutagenized and mutants were selected for the ability to hydrolyze glutaryl-(L)-leucine and provide leucine to Leu- host cells. Cells with the wild-type enzyme did not grow in minimal medium containing glutaryl-(L)-leucine as a sole source of leucine. The growth rates of Leu- cells that expressed these mutant amidases increased as the glutaryl-(L)-leucine concentration increased or as the medium pH decreased. Growth of the mutant strains was restricted by modulation of medium pH and glutaryl-(L)-leucine concentration, and successive generations of mutants that more efficiently hydrolyzed glutaryl-(L)-leucine were isolated. The kinetics of glutaryl-(L)-leucine hydrolysis by purified amidases from two mutants and the respective parental strains were determined. Glutaryl-(L)-leucine hydrolysis by the purified mutant amidases occurred most rapidly between pH 5 and 6, whereas hydrolysis by wild-type penicillin amidase at this pH was negligible. The second-order rate constants for glutaryl-(L)-leucine hydrolysis by two "second-generation" mutant amidases, 48 and 77 M-1 s-1, were higher than the rates of hydrolysis by the respective parental amidases. The increased rates of glutaryl-(L)-leucine hydrolysis resulted from both increases in the molecular rate constants and decreases in apparent Km values. The results show that it is possible to deliberately modify the substrate specificity of penicillin amidase and successively select mutants with amidases that are progressively more efficient at hydrolyzing glutaryl-(L)-leucine.

Hepatitis A and non-A, non-B viral hepatitis in São Paulo, Brazil: epidemiological, clinical and laboratory comparisons in hospitalized patients

During a 33-month period, 295 patients with acute viral hepatitis were admitted to a state hospital for civil servants and their dependents in São Paulo, Brazil. Seventy-nine per cent (232) were HBsAg negative. To define the contribution of non-A, non-B viral hepatitis to hepatitis morbidity in this population, further serological studies were performed in 147 confirmed HBsAg-negative patients. One hundred and twelve (76%) were serologically classified as hepatitis A based on identification of IgM antibody to hepatitis A virus. Thirty patients (20%) without IgM antibody to hepatitis A virus, HBsAg, or anti-HBc were categorized as the non-A, non-B hepatitis group. The remaining five patients had probable hepatitis B (IgM antibody to hepatitis A virus negative, HBsAg negative, anti-HBs negative but anti-HBc positive). These data suggest that all three etiological forms of viral hepatitis are endemic in São Paulo. Epidemiological, clinical, and laboratory features were compared to the hepatitis A and non-A, non-B hepatitis groups. Patients with non-A, non-B hepatitis were significantly older than patients with hepatitis A (mean age +/- S.D.: 30 +/- 22 years vs. 9 +/- 9 years, p less than 0.001). Contact with hepatitis or jaundice was recognized in 26 (23%) of 112 hepatitis A patients and 3 (10%) of 30 non-A, non-B patients, a difference which was not statistically significant. Parenteral exposures were identified in 13 (43%) of 30 patients with non-A, non-B hepatitis and 23 (21%) of the 112 hepatitis A patients. Blood transfusion in the 2 months preceding onset of illness was reported in 5 (17%) of the 30 non-A, non-B patients and in none of the hepatitis A group (p less than 0.001). Although prodromal symptoms and fever were more common in patients with hepatitis A, neither these nor other clinical features appeared to be distinguishing characteristics. Similarly, mean peak SGPT levels, peak SGPT levels of greater than or equal to 1,000 IU/per liter, and the mean duration of SGPT elevations for each group were not significantly different. Mean peak serum bilirubin levels were slightly higher in the non-A, non-B group than in the hepatitis A group (7.6 +/- 8.0 mg per dl vs. 5.1 +/- 2.7, p less than 0.01) and peak bilirubin levels greater than or equal to 10 mg per dl were found in 27% of the non-A, non-B group and 5% of the hepatitis A group (p less than 0.001). Whether the higher bilirubin levels reflect an agent-related phenomenon or an older population of affected patients is uncertain.

Natural and experimental infection of woodchucks with woodchuck hepatitis virus, as measured by new, specific assays for woodchuck surface antigen and antibody

Solid-phase radioimmunoassays for woodchuck hepatitis virus (WHV) surface antigen (WHsAg) and antibody to it (anti-WHs) were developed. The test for WHsAg could detect as little as 10 ng/ml. In both tests it was necessary to employ radiolabeled WHsAg instead of anti-WHs as the probe because the latter appeared to be labile to the conditions of labeling. The tests were used to characterize naturally acquired and experimental WHV infections of woodchucks. Forty-three of 72 wild-caught woodchucks had serological evidence of WHV infections; 16 of these resulted in chronic infection, and the remainder were self-limiting. All chronically infected animals were positive for WHsAg and DNA polymerase activity. During 3 years of observation, 11 of the 16 WHsAg-positive animals and 3 of the 27 anti-WHs-positive animals, but none of the 21 uninfected animals developed hepatocellular carcinoma. Seroconversion, possibly resulting from infection with WHV, was documented in a chimpanzee inoculated with WHV. An immune adherence hemagglutination test for WHsAg was also developed by using anti-WHs of chimpanzee origin as a reagent, but the test was not useful for detecting anti-WHs of woodchuck origin because of the lability of the latter.

Woodchuck hepatitis and hepatocellular carcinoma: correlation of histologic with virologic observations

The livers of 33 captive woodchucks were examined histologically in 30 biopsy and 10 autopsy specimens and the findings were correlated with serum determinations for woodchuck hepatitis virus (WHV), surface antigen (WHsAg) and antibody (anti-WHs), and WHV DNA and DNA polymerase. The liver appeared normal in all 3 serum-negative animals, 7 of 16 with indeterminate WHV status, and 1 of 4 with anti-WHs, but not in 10 animals with WHsAg, WHV DNA, and DNA polymerase. Mild hepatic inflammation was found in 7 woodchucks with indeterminate status, 4 with anti-WHs, and 2 with each marker of WHV infection. Significant inflammation was found in 2 of indeterminate status and 4 with every marker, whereas more severe lesions (2 of chronic active type) occurred, almost always in autopsy specimens, in 8 animals with every marker. Eight of 10 animals with all markers had orcein-positive inclusions (Shikata's technique) and 6 had hepatocellular carcinoma associated with acute and chronic hepatic inflammation and, usually, neoplastic nodules in the noncarcinomatous parenchyma. Features distinguishing the woodchuck lesion from human hepatitis B disease were: association of carcinoma with acute hepatic inflammation (but not with cirrhosis) and DNA polymerase in the serum; transition to carcinoma from neoplastic nodules; conspicuous plasma-cellular reaction of hepatic inflammation, and hematopoietic cells in the tumor. Significant hepatic lesions in the woodchucks were regularly associated with serum WHsAg, WHV DNA, and DNA polymerase. In contrast to man, hepatocellular carcinoma in woodchucks was regularly associated with these markers of active viral replication. The nature of the orcein-positive inclusions requires elucidation, although they may assist in screening for similar viruses in other species. The woodchuck may help in the study of the relation between hepatocellular carcinoma and hepatitis B, including the possibility of cocarcinogenic factors.

Serodiagnosis of viral hepatitis A by a solid-phase radioimmunoassay specific for IgM antibodies

A solid-phase radioimmunoassay for detecting specific IgM antibodies to hepatitis A virus (HAV) was developed and characterized. The test utilized microtiter plates coated with anti-IgM to specifically absorb the IgM antibodies from the test serum. The anti-hepatitis A IgM antibodies are measured by the specific consecutive binding of hepatitis A antigen and radiolabelled anti-hepatitis A antibodies (anti-HA). In 6 chimpanzees infected with HAV, IgM anti-HA was detected from about the first date of elevated transaminases and was positive for about 3 months. The usefulness of the test was confirmed by testing acute phase sera of 30 patients from a common source outbreak of epidemic hepatitis, and negative sera from 2 control groups. A collection of serum specimens from 190 patients with sporadic HBsAg-negative hepatitis in Brazil was also tested and an etiologic association with HAV was confirmed in the majority of these cases.

PLC/PRF/5 (Alexander) hepatoma cell line: further characterization and studies of infectivity

The Alexander hepatoma cell line, PLC/PRF/5, was studied for evidence of hepatitis B virus markers and alpha-fetoprotein. Only hepatitis B surface antigen and alpha-fetoprotein were detected. Induction experiments with 5-iodo-2'-deoxyuridine and inoculation of chimpanzees with whole cells or tissue culture fluid did not reveal evidence of synthesis of additional hepatitis B virus markers or of production of infectious virus.

Epidemic and endemic hepatitis in India: evidence for a non-A, non-B hepatitis virus aetiology

69 serum pairs from two common-source water-borne outbreaks and one series of endemic cases of hepatitis in three parts of India were tested for hepatitis A and hepatitis B virus infections. None of the patients had evidence of HAV infection and only 10.1% had evidence of HBV infection. A large proportion of hepatitis in India seems to be caused by previously unrecognised agents.

Prevalence of antibody to hepatitis A and hepatitis B viruses in selected populations of the South Pacific

Five island populations representing the three major cultural groups of the South Pacific--Polynesia, Micronesia, Melanesia--were studied for prevalence of antibody to hepatitis A virus (anti-HAV) and of antibody to the core antigen of hepatitis B virus (anti-HBc). Sera were collected in the late 1950s and early 1960s, selected where possible for appropriate age and sex distributions, and were tested by radioimmunoassay. Rather marked differences in prevalence were observed. Anti-HBc patterns confirmed that HBV is endemic in the Pacific populations. Furthermore, the patterns differed somewhat from each other and did not correlate with ethnogeographic area. Prevalence of anti-HAV was high in all populations studied. A Unique pattern was found for the island of Ponape (Micronesia): In a Ponape population bled in 1963, anti-HAV was not detected in any individual under 20 years of age, but almost all individuals over that age were found to be seropositive. On testing a second group of sera collected in 1975, all individuals aged 14--21 years were found to be antibody positive, indicating that HAV had returned to Ponape sometime prior to 1975. There was no significant difference in the prevalence of HAV or HBV infection between males and females in any of the populations studied.

Enzyme-linked immunosorbent assay for detection of hepatitis A antigen in stool and antibody to hepatitis A antigen in sera: comparison with solid-phase radioimmunoassay, immune electron microscopy, and immune adherence hemagglutination assay

Previously described techniques for detection of hepatitis A antigen (HA Ag) and antibody (anti-HA) have required purified HA Ag and expensive equipment. Herein is described an enzyme-linked immunosorbent assay (ELISA) for specific detection of HA Ag in human stool filtrates and of anti-HA in sera by using selected HA Ag-containing human stool filtrates as the antigen source. Because human stools often react nonspecifically in serological tests for HA Ag, blocking with preexposure and hyperimmune anti-HA sera from a chimpanzee inoculated with hepatitis A virus was used to confirm specific detection of HA Ag. The sensitivity of ELISA was found to be comparable to that of solid-phase radioimmunoassay (SPRIA) and immune electron microscopy (IEM). Of 37 acute-phase stools collected from nine patients, 16 were positive for HA Ag by ELISA. In 13 of these, HA Ag particles were found by IEM, and an additional 3 stools negative by ELISA contained HA Ag particles by IEM. Eight control stools were negative by both ELISA and IEM. Anti-HA was measured in sera by demonstrating its ability to block binding of the enzyme conjugate to HA Ag in a stool without detectable nonspecificity. This test (blocking ELISA) was as sensitive and specific as blocking SPIRA, IEM, and immune adherence hemagglutination and, like SPRIA and IEM, detected early-developing antibody. The ELISA is simple to perform and requires only a minimum of equipment. It is useful for screening stools for HA Ag and for monitoring HA Ag during purification, as well as for detecting early and late anti-HA in sera.

Serologic and animal inoculation studies of a communal outbreak of viral hepatitis, type A

Sera from individuals in an outbreak of viral hepatitis in a multifamily household, probably spread by contaminated food, were studied for antibodies to hepatitis A virus (anti-HAV), and selected acute phase sera were inoculated into marmosets. Significant rises in anti-HAV titers between acute and convalescent sera occurred in all of 15 individuals in the outbreak who experienced serum enzyme elevations and in one of 14 individuals whose serum enzyme levels remained normal. The remaining 13 individuals in the latter group had antibody levels in both early and late sera compatible with residual immunity from prior HAV infections and correlating with resistance to reinfection. Groups of marmosets were infected with acute phase sera from two of the cases; in both instances the inoculated sera contained substantial levels of anti-HAV. The marmosets developed specific anti-HAV seroconversions as well as enzyme elevations.