Hospitalization is a missed opportunity for HIV screening, pre-exposure prophylaxis, and treatment

BACKGROUND

Hospitalization is a "reachable moment" for people who inject drugs (PWID), but preventive care including HIV testing, prevention and treatment is rarely offered within inpatient settings.

METHODS

We conducted a multisite, retrospective cohort study of patients with opioid use disorder with infectious complications of injection drug use hospitalized between 1/1/2018-12/31/2018. We evaluated HIV care continuum outcomes using descriptive statistics and hypothesis tests for intergroup differences.

RESULTS

322 patients were included. Of 300 patients without known HIV, only 2 had a documented discussion of PrEP, while only 1 was prescribed PrEP on discharge. Among the 22 people with HIV (PWH), only 13 (59%) had a viral load collected during admission of whom all were viremic and 10 (45%) were successfully linked to care post-discharge. Rates of readmission, Medicaid or uninsured status, and unstable housing were high in both groups.

DISCUSSION

We observed poor provision of HIV testing, PrEP and other HIV services for hospitalized PWID across multiple U.S. medical centers. Future initiatives should focus on providing this group with comprehensive HIV testing and treatment services through a status neutral approach.

Xylazine co-occurrence with illicit fentanyl is a growing threat in the Deep South: a retrospective study of decedent data

BACKGROUND

Xylazine is a dangerous veterinary sedative found mainly in illicit fentanyl in the Northeast and Midwest. Its role in the Deep South overdose crisis is not well-characterized.

METHODS

We conducted a retrospective review of autopsy data in Jefferson County, Alabama to identify trends in xylazine prevalence among people who fatally overdosed from June 2019 through June 2023.

RESULTS

165 decedents met inclusion criteria. While the first identified xylazine-associated overdose was in June 2019, xylazine has become consistently prevalent since January 2021. All cases of xylazine-associated fatal overdoses were accompanied by fentanyl, and most (75.4%) involved poly-drug stimulant use. The average age was 42.2, and most decedents were white (58.8%) and male (68.5%). Overall, 18.2% of people were unhoused at the time of death.

DISCUSSION

Xylazine is prevalent in the Deep South. Efforts to promote harm reduction, publicly viewable drug supply trends, and legalization of drug checking and syringe service programs should be prioritized.

331. Blood Culture Identification (BCID) Performance in Polymicrobial Bacteremia

Background

The rapid multiplex PCR (rmPCR)-based FilmArray® blood culture identification (BCID) assay reduces time from positive blood culture to organism identification. Polymicrobial bacteremia is a known area of reduced diagnostic fidelity for BCID and remains incompletely characterized.

Methods

All cases of clinically confirmed polymicrobial bacteremia at a large academic single center from a 23-month period were evaluated in a retrospective cohort analysis (figure 1). Samples were assorted into BCID/blood culture concordant and BCID/blood culture discordant groups. Clinical characteristics of the two groups were compared, missed organisms were characterized, and changes in antimicrobial regimen in response to BCID results were characterized. Figure 1.

Screening and exclusion process. 207 cultures were included in final analysis from a number screened of 2750 (constituting all positive blood cultures over a 23-month period from February 2019 to January 2021). Microbiologic inclusion criteria were as follows: evidence on final phenotypic culture of at least two separate microorganisms from the same blood culture specimen as long as both organisms were species other than coagulase negative staphylococci.

Results

A total of 207 samples were identified and studied. Overall, 49.3% (N=102) of polymicrobial cultures were incompletely identified by FilmArray® result. There were no significant group differences in comorbidity status, length of stay, mortality, or source between patients with polymicrobial bacteremia who had complete versus incomplete BCID identification (see table 1). Some 29.9% (38 of 127 total) of species identified corresponded to an organism potentially requiring time-sensitive treatment (relative numbers of each shown in table 2). De-escalation from adequate empiric to inadequate step-down antibiotic coverage following incomplete BCID result occurred in only 8.8% (N=9) of cases (shown in table 3). Table 1.

Comparison of the characteristics of the BCID/blood culture (BCx) concordant and BCID/BCx discordant groups. Abbreviations: BCx, blood culture; IQR, interquartile range; ICU, intensive care unit; ER, emergency room; TPN, total parenteral nutrition. Table 2.

Discrepant organisms typically requiring timely treatment identified on blood culture phenotyping but not on BCID. A complete list can be found in supplemental table S1. Table 3.

Among patients with inaccurate BCIDs, antimicrobial changes and outcomes following return of BCID result are shown below. P-values comparing the four groups are shown. There was no significant association that could be seen in mortality and time to discharge and patient’s empiric therapy and de-escalation therapy status. Abbreviations: IQR, interquartile range; N/A, not applicable.

Conclusion

BCID frequently results in incomplete identification of blood culture results in patients with polymicrobial bacteremia, but clinical characteristics and outcomes were similar to those of patients with accurate BCID identification. Clinical team de-escalation to inappropriate antibiotic coverage following return the BCID assay was uncommon and was not clearly associated with inferior outcomes.

Disclosures

All Authors: No reported disclosures.

Abstract MP218: Cop9 Signalosome Subunit 6 Restricts Desmosomal Proteome Degradation To Prevent Desmosomal Targeted Cardiac Disease

Dysregulated protein degradative pathways are increasingly recognized as mediators of human cardiac disease. This pathway may have particular relevance to desmosomal proteins that play critical structural roles in both tissue architecture and cell-cell communication. Genetic mutations in desmosomal genes resulting in the destabilization/breakdown of the desmosomal proteome are a central hallmark of all genetic-based desmosomal-targeted diseases, including the cardiac disease arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C). However, no information exists on whether there are resident proteins that regulate desmosomal proteome homeostasis. Here we identified a desmosomal resident regulatory complex, composed of subunit 6 of the COP9 signalosome (CSN6), enzymatically restricted neddylation and targets desmosomal proteome. Pharmacological restoration of CSN enzymatic function (via neddylation inhibitors) could rescue desmosomal protein loss in CSN6 deficient cardiomyocytes. Through the generation of two novel mouse models, we showed that cardiomyocyte-restricted CSN6 loss in mice selectively accelerated desmosomal destruction to trigger classic disease features associated with ARVD/C. We further showed that disruption of CSN6-mediated (neddylation) pathways underlined ARVD/C as CSN6 binding, localization, levels and function were impacted in hearts of classic ARVD/C mouse models and ARVD/C patients impacted by desmosomal loss and mutations, respectively. We anticipate our findings have broad implications towards understanding mechanisms driving desmosome degradation in other desmosomal-based diseases, such as cancers.

Reduction of myocardial ischaemia-reperfusion injury by inactivating oxidized phospholipids

Aims

Myocardial ischaemia followed by reperfusion (IR) causes an oxidative burst resulting in cellular dysfunction. Little is known about the impact of oxidative stress on cardiomyocyte lipids and their role in cardiac cell death. Our goal was to identify oxidized phosphatidylcholine-containing phospholipids (OxPL) generated during IR, and to determine their impact on cell viability and myocardial infarct size.

Methods and results

OxPL were quantitated in isolated rat cardiomyocytes using mass spectrophotometry following 24 h of IR. Cardiomyocyte cell death was quantitated following exogenously added OxPL and in the absence or presence of E06, a 'natural' murine monoclonal antibody that binds to the PC headgroup of OxPL. The impact of OxPL on mitochondria in cardiomyocytes was also determined using cell fractionation and Bnip expression. Transgenic Ldlr-/- mice, overexpressing a single-chain variable fragment of E06 (Ldlr-/--E06-scFv-Tg) were used to assess the effect of inactivating endogenously generated OxPL in vivo on myocardial infarct size. Following IR in vitro, isolated rat cardiomyocytes showed a significant increase in the specific OxPLs PONPC, POVPC, PAzPC, and PGPC (P < 0.05 to P < 0.001 for all). Exogenously added OxPLs resulted in significant death of rat cardiomyocytes, an effect inhibited by E06 (percent cell death with added POVPC was 22.6 ± 4.14% and with PONPC was 25.3 ± 3.4% compared to 8.0 ± 1.6% and 6.4 ± 1.0%, respectively, with the addition of E06, P < 0.05 for both). IR increased mitochondrial content of OxPL in rat cardiomyocytes and also increased expression of Bcl-2 death protein 3 (Bnip3), which was inhibited in presence of E06. Notably cardiomyocytes with Bnip3 knock-down were protected against cytotoxic effects of OxPL. In mice exposed to myocardial IR in vivo, compared to Ldlr-/- mice, Ldlr-/--E06-scFv-Tg mice had significantly smaller myocardial infarct size normalized to area at risk (72.4 ± 21.9% vs. 47.7 ± 17.6%, P = 0.023).

Conclusions

OxPL are generated within cardiomyocytes during IR and have detrimental effects on cardiomyocyte viability. Inactivation of OxPL in vivo results in a reduction of infarct size.

2788. Case Report: Severe Community-Acquired Human Adenovirus 7 Infection in a Mother and Son

Background

We present the case of a 42-year-old male (Patient 1) with a history of morbid obesity and cirrhosis of unclear etiology who died of acute hypoxic respiratory failure and devastating encephalitis after community-acquired infection with human adenovirus 7 (HAdV7) in spite of antiviral treatment with Cidofovir. Patient 1’s course is outlined in Figure 1. During his stay, the patient’s mother (Patient 2) was also hospitalized in the same unit following a similar presentation with 10 days of flu-like symptoms that progressed to ARDS requiring intubation. Patient 2 recovered from her infection with no specific antiviral treatment.

Methods

N/A.

Results

These cases illustrate particularly fulminant presentations of HAdV7 infection and highlight the high pathogenicity of HAdV7 compared with other adenovirus subtypes. Severe lower respiratory tract HAdV7 infections have been reported most commonly as outbreaks of respiratory illness among military recruits and infants. A notable recent outbreak of HAdV-7d in New Jersey in 2016–2017 resulted in 12 confirmed cases with 4 deaths; however, all deaths occurred in patients with significant medical comorbidities.¹ In a case particularly striking for its similarity to the one presented here, a healthy 44-year-old male along with his 68-year-old father were hospitalized with human adenovirus 7 days infection in Chicago in December 2014, with the son requiring ECMO for ARDS and the father briefly requiring ICU-level care.²

Conclusion

While our patient’s case is by no means unprecedented, it does represent an uncommon and potentially serious infection that points to need for continuing nosocomial testing efforts and deserves special attention in outbreak settings. In the future, perhaps use of the extant vaccine for human adenovirus serotypes 4 and 7 (currently licensed for military personnel³) could be expanded for use in civilian populations could be explored and potentially expanded for use in outbreak settings.

Disclosures

All authors: No reported disclosures.

Future directions in idiopathic pulmonary fibrosis research. An NHLBI workshop report

The median survival of patients with idiopathic pulmonary fibrosis (IPF) continues to be approximately 3 years from the time of diagnosis, underscoring the lack of effective medical therapies for this disease. In the United States alone, approximately 40,000 patients die of this disease annually. In November 2012, the NHLBI held a workshop aimed at coordinating research efforts and accelerating the development of IPF therapies. Basic, translational, and clinical researchers gathered with representatives from the NHLBI, patient advocacy groups, pharmaceutical companies, and the U.S. Food and Drug Administration to review the current state of IPF research and identify priority areas, opportunities for collaborations, and directions for future research. The workshop was organized into groups that were tasked with assessing and making recommendations to promote progress in one of the following six critical areas of research: (1) biology of alveolar epithelial injury and aberrant repair; (2) role of extracellular matrix; (3) preclinical modeling; (4) role of inflammation and immunity; (5) genetic, epigenetic, and environmental determinants; (6) translation of discoveries into diagnostics and therapeutics. The workshop recommendations provide a basis for directing future research and strategic planning by scientific, professional, and patient communities and the NHLBI.

Eukaryotic G protein signaling evolved to require G protein-coupled receptors for activation

Although bioinformatic analysis of the increasing numbers of diverse genome sequences and amount of functional data has provided insight into the evolution of signaling networks, bioinformatics approaches have limited application for understanding the evolution of highly divergent protein families. We used biochemical analyses to determine the in vitro properties of selected divergent components of the heterotrimeric guanine nucleotide-binding protein (G protein) signaling network to investigate signaling network evolution. In animals, G proteins are activated by cell-surface seven-transmembrane (7TM) receptors, which are named G protein-coupled receptors (GPCRs) and function as guanine nucleotide exchange factors (GEFs). In contrast, the plant G protein is intrinsically active, and a 7TM protein terminates G protein activity by functioning as a guanosine triphosphatase-activating protein (GAP). We showed that ancient regulation of the G protein active state is GPCR-independent and "self-activating," a property that is maintained in Bikonts, one of the two fundamental evolutionary clades containing eukaryotes, whereas G proteins of the other clade, the Unikonts, evolved from being GEF-independent to being GEF-dependent. Self-activating G proteins near the base of the Eukaryota are controlled by 7TM-GAPs, suggesting that the ancestral regulator of G protein activation was a GAP-functioning receptor, not a GEF-functioning GPCR. Our findings indicate that the GPCR paradigm describes a recently evolved network architecture found in a relatively small group of Eukaryota and suggest that the evolution of signaling network architecture is constrained by the availability of molecules that control the activation state of nexus proteins.

G protein activation without a GEF in the plant kingdom

Animal heterotrimeric G proteins are activated by guanine nucleotide exchange factors (GEF), typically seven transmembrane receptors that trigger GDP release and subsequent GTP binding. In contrast, the Arabidopsis thaliana G protein (AtGPA1) rapidly activates itself without a GEF and is instead regulated by a seven transmembrane Regulator of G protein Signaling (7TM-RGS) protein that promotes GTP hydrolysis to reset the inactive (GDP-bound) state. It is not known if this unusual activation is a major and constraining part of the evolutionary history of G signaling in eukaryotes. In particular, it is not known if this is an ancestral form or if this mechanism is maintained, and therefore constrained, within the plant kingdom. To determine if this mode of signal regulation is conserved throughout the plant kingdom, we analyzed available plant genomes for G protein signaling components, and we purified individually the plant components encoded in an informative set of plant genomes in order to determine their activation properties in vitro. While the subunits of the heterotrimeric G protein complex are encoded in vascular plant genomes, the 7TM-RGS genes were lost in all investigated grasses. Despite the absence of a Gα-inactivating protein in grasses, all vascular plant Gα proteins examined rapidly released GDP without a receptor and slowly hydrolyzed GTP, indicating that these Gα are self-activating. We showed further that a single amino acid substitution found naturally in grass Gα proteins reduced the Gα-RGS interaction, and this amino acid substitution occurred before the loss of the RGS gene in the grass lineage. Like grasses, non-vascular plants also appear to lack RGS proteins. However, unlike grasses, one representative non-vascular plant Gα showed rapid GTP hydrolysis, likely compensating for the loss of the RGS gene. Our findings, the loss of a regulatory gene and the retention of the "self-activating" trait, indicate the existence of divergent Gα regulatory mechanisms in the plant kingdom. In the grasses, purifying selection on the regulatory gene was lost after the physical decoupling of the RGS protein and its cognate Gα partner. More broadly these findings show extreme divergence in Gα activation and regulation that played a critical role in the evolution of G protein signaling pathways.

Oral combination therapy with a nucleoside polymerase inhibitor (RG7128) and danoprevir for chronic hepatitis C genotype 1 infection (INFORM-1): a randomised, double-blind, placebo-controlled, dose-escalation trial

BACKGROUND

Present interferon-based standard of care treatment for chronic hepatitis C virus (HCV) infection is limited by both efficacy and tolerability. We assessed the safety, tolerability, and antiviral activity of an all-oral combination treatment with two experimental anti-HCV drugs-RG7128, a nucleoside polymerase inhibitor; and danoprevir, an NS3/4A protease inhibitor-in patients with chronic HCV infection.

METHODS

Patients from six centres in New Zealand and Australia who were chronically infected with HCV genotype 1 received up to 13 days oral combination treatment with RG7128 (500 mg or 1000 mg twice daily) and danoprevir (100 mg or 200 mg every 8 h or 600 mg or 900 mg twice daily) or placebo. Eligible patients were sequentially enrolled into one of seven treatment cohorts and were randomly assigned by interactive voice or web response system to either active treatment or placebo. Patients were separately randomly assigned within each cohort with a block size that reflected the number of patients in the cohort and the ratio of treatment to placebo. The random allocation schedule was computer generated. Dose escalation was started in HCV treatment-naive patients; standard of care treatment-experienced patients, including previous null responders, were enrolled in higher-dose danoprevir cohorts. Investigators, personnel at the study centre, and patients were masked to treatment allocation. However, the pharmacist who prepared the doses, personnel involved in pharmacokinetic sample analyses, statisticians who prepared data summaries, and the clinical pharmacologists who reviewed the data before deciding to initiate dosing in the next cohort were not masked to treatment allocation. The primary outcome was change in HCV RNA concentration from baseline to day 14 in patients who received 13 days of combination treatment. All patients who completed treatment with the study drugs were included in the analyses. This study is registered with ClinicalTrials.gov, NCT00801255.

FINDINGS

88 patients were randomly assigned to a study drug treatment regimen (n=74 over seven treatment groups; 73 received at least one dose of study drug) or to placebo (n=14, all of whom received at least one dose). The median change in HCV RNA concentration from baseline to day 14 ranged from -3·7 to -5·2 log(10) IU/mL in the cohorts that received 13 days of combination treatment. At the highest combination doses tested (1000 mg RG7128 and 900 mg danoprevir twice daily), the median change in HCV RNA concentration from baseline to day 14 was -5·1 log(10) IU/mL (IQR -5·6 to -4·7) in treatment-naive patients and -4·9 log(10) IU/mL in previous standard of care null responders (-5·2 to -4·5) compared with an increase of 0·1 log(10) IU/mL in the placebo group. The combination of RG7128 and danoprevir was well tolerated with no treatment-related serious or severe adverse events, no grade 3 or 4 changes in laboratory parameters, and no safety-related treatment discontinuations.

INTERPRETATION

This oral combination of a nucleoside analogue polymerase inhibitor and protease inhibitor holds promise as an interferon-free treatment for chronic HCV.

FUNDING

Roche Palo Alto.

Targeted disruption of Drosophila Roc1b reveals functional differences in the Roc subunit of Cullin-dependent E3 ubiquitin ligases

Cullin-dependent ubiquitin ligases regulate a variety of cellular and developmental processes by recruiting specific proteins for ubiquitin-mediated degradation. Cullin proteins form a scaffold for two functional modules: a catalytic module comprised of a small RING domain protein Roc1/Rbx1 and a ubiquitin-conjugating enzyme (E2), and a substrate recruitment module containing one or more proteins that bind to and bring the substrate in proximity to the catalytic module. Here, we present evidence that the three Drosophila Roc proteins are not functionally equivalent. Mutation of Roc1a causes lethality that cannot be rescued by expression of Roc1b or Roc2 by using the Roc1a promoter. Roc1a mutant cells hyperaccumulate Cubitus interruptus, a transcription factor that mediates Hedgehog signaling. This phenotype is not rescued by expression of Roc2 and only partially by expression of Roc1b. Targeted disruption of Roc1b causes male sterility that is partially rescued by expression of Roc1a by using the Roc1b promoter, but not by similar expression of Roc2. These data indicate that Roc proteins play nonredundant roles during development. Coimmunoprecipitation followed by Western or mass spectrometric analysis indicate that the three Roc proteins preferentially bind certain Cullins, providing a possible explanation for the distinct biological activities of each Drosophila Roc/Rbx.

Expression analysis of the T-cell-targeting chemokines CXCL9 and CXCL10 in mice and humans with endothelial infections caused by rickettsiae of the spotted fever group

Rocky Mountain spotted fever and other related diseases are systemic infections caused by rickettsiae. These obligatory intracellular bacteria target the endothelium, offering an appealing model to study the interactions between endothelial cells and T lymphocytes. We investigated the mRNA expression of chemokines known to target CD8+ T cells and CD4(+) T-helper 1 cells in the lungs of C3H/HeN mice infected with Rickettsia conorii with the purpose of identifying evidence for a role of chemokines in the immune clearance of rickettsiae from the vasculature. The expression of the CXCR3 ligands CXCL9 and CXCL10 was significantly higher than the other chemokines investigated. We validated the relevance of these results in the animal model through the analysis of tissues from humans with Rocky Mountain spotted fever. We then characterized the kinetics and localization of expression of CXCL9 and CXCL10 in lungs, brain, and liver of mice infected with lethal or sublethal doses of R. conorii by a combination of quantitative real-time polymerase chain reaction and immunohistochemistry. Interestingly, the peak of expression of these chemokines occurred 4 days before CD8+ T cells infiltrated the infected tissues. Our results suggest that CXCL9 and CXCL10 may play a role early during the immune response against rickettsial infections.

Inspissation of pancreatic zymogen material in cystic fibrosis

Cystic fibrosis is characterized by the elaboration of abnormal, thick, tenacious mucus resulting in obstructive disease in sites such as the lung and pancreas. In the pancreas, acinar plugs of mucus have been reported as the earliest recognizable morphologic lesion in cystic fibrosis. Since mucus is not normally elaborated within the pancreatic lobular tissue, the mechanism of accumulation of mucus in acini is enigmatic. To investigate this phenomenon, well-preserved autopsy pancreatic tissue was studied ultrastructurally. This study demonstrated very prominent mucous metaplasia in these diseased organs. Acinar plugs, though, developed before mucous metaplasia. Subsequent histochemical study was performed, which demonstrated that the early acinar plugs exhibited the same staining properties as zymogen granules and were distinct from the staining pattern of mucus in pancreatic tissue of cystic fibrosis patients. These findings, then, indicate that zymogen material, not mucus, becomes inspissated in the acini of the pancreas in early cystic fibrosis, and that subsequent mucous metaplasia occurs as the obstruction and exocrine atrophy progress.

Duke's 3rd year: a 35-year retrospective

PURPOSE

Our purpose was to review and evaluate Duke University School of Medicine's 3rd year.

SUMMARY

Duke University School of Medicine instituted a dramatic change in its curriculum 35 years ago by restructuring the 1st, 2nd, and 4th years of medical school so that the entire 3rd year could be devoted to an elective research experience or independent study of the basic sciences. Today this "new curriculum" permits students to work in basic science laboratories or with clinical investigators, work toward a 2nd degree, and participate in basic science courses beyond the core curriculum. Students were surveyed in 1996 and 1998 about their 3rd-year experience. Results showed that 67% and 73%, respectively, believed the 3rd year was very helpful in facilitating their understanding and appreciation of biomedical and clinical research. Students especially valued the experience and availability of their preceptors and the range of opportunities available during the 3rd year. The most frequent critiques by students were the lack of opportunities to pursue clinical interests, difficulty integrating the 3rd year into the remainder of the curriculum, and a tendency to place too much emphasis on coupling the 3rd-year experience with scholarships and residency plans rather than on a specific investigative interest.

CONCLUSIONS

Overall, both faculty and students value the 3rd year as a unique positive experience. Duke faculty have noted, however, that no other medical schools have attempted to replicate the Duke experience.

Cytogenetics and mechanisms of spontaneous abortions: increased apoptosis and decreased cell proliferation in chromosomally abnormal villi

Genetic defects of the zygote, such as chromosome aberrations, are the most frequent causes of abnormal embryonic development and spontaneous abortion. However, the underlying mechanisms remain unknown. Chromosome aberrations likely cause changes in placental morphology and function (such as size, shape, vascularity, and the presence of trophoblastic inclusion). We postulated that chromosome aberrations may affect rates of cell proliferation or programmed cell death (apoptosis) during the differentiation of chorionic villi. To address these questions, we evaluated cell proliferation using a monoclonal antibody to Ki-67 (a cell-cycle marker) and apoptosis using the in situ end-labeling method (TUNEL) on paraffin-embedded placental tissues. Tissues were obtained from spontaneous abortions in early gestational periods with normal (11 cases) and abnormal karyotypes (15 cases), as well as eight normal control placentas from elective abortions. Apoptotic cells were found in the stroma of all cases, but were significantly higher in number in the stroma of chromosomally abnormal versus chromosomally normal spontaneous abortions. The apoptotic index of the trophoblasts was not significantly different between groups. Cell proliferation was higher in muscularized blood vessels in chromosomally normal placentas (both elective and spontaneous abortions) versus chromosomally abnormal spontaneous abortions. Cell proliferation was different in the trophoblast and stroma between the groups but to a lesser degree than in blood vessels. The morphological and biological data presented here suggest that: (1) chromosomally abnormal spontaneous abortions may occur because of different mechanisms than chromosomally normal spontaneous abortions, (2) apoptosis of the stromal cells and cell proliferation in blood vessels and stroma play an important role in the differentiation and functioning of villi, and (3) these changes could explain the etiology of spontaneous abortion and growth retardation of chromosomally abnormal embryos.

Hepatic parenchymal cells in cystic fibrosis: ultrastructural evidence for abnormal intracellular transport

Few ultrastructural observations of hepatic parenchymal cells in cystic fibrosis (CF) have appeared in the literature. Utilizing a unique opportunity to examine freshly fixed hepatic tissue by transmission electron microscopy, we studied 12 patients dying with CF at Duke Hospital from 1979 to 1981 in order to identify possible abnormalities of intracellular architecture. The major findings include (1) intracellular fatty vacuoles, (2) distended bile ductules and bile ducts containing increased cellular debris, (3) profiles of distended rough endoplasmic reticulum containing material of medium electron density, and (4) membrane-bound deposits of electron-lucent material containing electron-dense cores resembling mucus. We suggest that the material seen within the cytocavitary network reflects a derangement of intracellular transport.