Hepatic venous pressure gradient in sinusoidal obstruction syndrome: diagnostic value and link with histological lesions

Background & Aims

Liver sinusoidal obstruction syndrome (SOS) is a well-established complication of myeloablative conditioning regimens used in hematopoietic stem cell transplantation. Hepatic venous pressure gradient (HVPG) >10 mmHg was described as an accurate diagnostic tool for SOS in the 1990s. However, epidemiology and presentation of SOS have dramatically changed. Moreover, elementary histological lesions influencing HVPG are unknown.

Methods

We retrospectively analyzed the charts of all patients who underwent transjugular liver biopsy with HVPG measurement for a clinical suspicion of SOS at our center. Two expert pathologists unaware of the presence or absence of SOS reviewed all liver samples and graded elementary histological lesions according to a semi-quantitative scoring defined a priori.

Results

Out of the 77 included patients, the 30 patients with SOS had higher HVPG than the 47 patients without SOS (median 14 mmHg [IQR 10-18], vs. 6 mmHg [3-9], respectively p <0.001). HVPG >10 mmHg had a specificity of 78% and a positive predictive value of 66% for the diagnosis of SOS. However, almost 40% of the patients with SOS had an HVPG ≤10 mmHg. HVPG correlated with sinusoidal congestion (r = 0.57; p = 0.001) and hepatocyte necrosis (r = 0.42; p = 0.02), but not with other lesions.

Conclusion

Even though HVPG is higher in patients with SOS, low HVPG values do not rule out SOS. Thus, HVPG cannot be used alone, and should be combined with transjugular liver biopsy, for the diagnosis of SOS.

Lay summary

Hepatic venous pressure gradient >10 mmHg has been described as an accurate tool for the diagnosis of liver sinusoidal obstruction syndrome after hematopoietic stem cell transplantation. This study shows that the sensitivity and specificity of hepatic venous pressure gradient measurement for sinusoidal obstruction syndrome are insufficient, so that liver pressure measurement should be combined with a liver biopsy in this setting.

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HVPG is significantly higher in patients with sinusoidal obstruction syndrome than in those with other liver injuries.

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A 10 mmHg threshold is associated with low PPV (66%) and low sensitivity (63%).

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HVPG measurement should be combined with transjugular liver biopsy when sinusoidal obstruction syndrome is suspected.

Drosophila ABC transporter mutants white, brown and scarlet have altered contents and distribution of biogenic amines in the brain

Monoamines such as dopamine, histamine and serotonin (5-HT) are widely distributed throughout the brain of the fruit fly Drosophila melanogaster, where many of their actions have been investigated. For example, histamine is released from photoreceptor synapses in the lamina neuropile of the visual system. Mutations of the genes white, an important eye pigmentation marker in fly genetics that encodes an ABC transporter, and its binding partner brown, cause neural phenotypes not readily reconciled solely with actions in eye pigmentation. We find that flies mutant for these genes, and another binding partner, scarlet, have about half the wild-type amount of histamine in the head, as well as reduced 5-HT and dopamine. These differences parallel reductions in immunoreactivity to the corresponding biogenic amines. They also correlate with the amine content of fractions after differential centrifugation of head homogenates. Thus, most of the amine is found in the vesicle-rich fraction of wild-type head homogenates, whereas it is found in the supernatant fractions from white, brown and scarlet flies. White co-expresses in lamina epithelial glia with Ebony, which conjugates histamine to β-alanine. Histamine is then released when the conjugate is hydrolyzed in photoreceptors, by Tan. Mutant white ameliorates the effects of tan on head histamine whereas it exacerbates the effects of ebony. Our results are consistent with the proposal that histamine uptake by the epithelial glia may be white dependent. Behavioral abnormalities in white, brown and scarlet mutants could arise because aminergic neurons in the Drosophila brain have reduced amine for release.

Parental imprinting in Drosophila

Genetic imprinting is a form of epigenetic silencing. But with a twist. The twist is that while imprinting results in the silencing of genes, chromosome regions or entire chromosome sets, this silencing occurs only after transmission of the imprinted region by one sex of parent. Thus genetic imprinting reflects intertwined levels of epigenetic and developmental modulation of gene expression. Imprinting has been well documented and studied in Drosophila, however, these studies have remained largely unknown due to nothing more significant than differences in terminology. Imprinting in Drosophila is invariably associated with heterochromatin or regions with unusual chromatin structure. The imprint appears to spread from imprinted centers that reside within heterochromatin and these are, seemingly, the only regions that are normally imprinted in Drosophila. This is significant as it implies that while imprinting occurs in Drosophila, it is generally without phenotypic consequence. Hence the evolution of imprinting, at least in Drosophila, is unlikely to be driven by the function of specific imprinted genes. Thus, the study of imprinting in Drosophila has the potential to illuminate the mechanism and biological function of imprinting, and challenge models based solely on imprinting of mammalian genes.

Not just pretty eyes: Drosophila eye-colour mutations and lysosomal delivery

Analysis of Drosophila eye-colour mutations has made seminal contributions to the fields of genetics and biochemistry. Recent findings suggest that a subset of eye-colour genes is crucial for vesicular transport of proteins to pigment granules, specialized lysosomes of eye-pigment cells. Thus, classical work describing more than 85 eye-colour mutations and their genetic interactions offers a remarkable, untapped resource for the genetic analysis of protein delivery to lysosomes.

A Markov model for the assembly of heterochromatic regions in position effect variegation

Here we give a mathematical model for the assembly of heterochromatic regions at the heterochromatin-euchromatin interface in position effect variegation. This probabilistic model predicts the proportions of cells in which a gene is active in cells with one and two variegating chromosomes. The association of heterochromatic proteins to form remodeled chromatin following DNA replication is mainly described by accumulation independent conditional probabilities. These probabilities are conditional on the boundary of the sites to which the proteins can bind; they give the relative attractiveness of the sites to a protein complex chosen at random from a pool of available complexes. The number of complexes available is assumed to be limited and rates of reaction are implicitly modeled by the conditional probabilities. In general, these conditional probabilities are not known, however, they can be experimentally determined. By comparing double variegation situations to single variegation, this model shows that there may be an effect on the expression of reporter genes located near the interfaces due to different sites competing for heterochromatic proteins. In addition, this model suggests that in some cases the attractiveness of sites may change in the presence of other chemical species. Consequently, the model distinguishes between two sorts of data obtained from competition experiments using position effect variegation. The two sorts of data differ as to whether there is a change in the attractiveness of sites in addition to an effect from different sites competing for the same constituents of heterochromatin. Subject to the fact that some of its parameters are not known precisely, this model replicates data from several experiments and can give predictions in other cases.

Long-term antiarrhythmic therapy with acetylprocainamide

Nineteen patients whose arrhythmias were initially suppressed with acetylprocainamide underwent long-term treatment with this drug. Eleven patients were still taking the drug at the end of 12 months. Drug withdrawal with substitution of a placebo caused an increase in ventricular premature beats. Thus, suppression of ventricular premature beats persisted for 1 year. The eight withdrawals from the study were due to death during the year (n = 6) or recurrence of arrhythmias. The deaths occurred in patients who were in New York Heart Association functional class II (one patient), III (three patients) and IV (two patients). Ventricular performance, assessed from systolic time intervals, improved with drug therapy and declined during drug withdrawal. Symptomatic effects were common, with seven patients requiring a reduction in dosage or discontinuation of therapy. Three patients treated for 3 years continued to show drug suppression of ventricular premature beats compared with the level during placebo substitution. Small amounts of procainamide were present in all patients because of in vivo deacetylation of acetylprocainamide. Many patients with good initial responses to this drug had recurrent arrhythmias during long-term therapy. For this reason, the usefulness of acetylprocainamide as an antiarrhythmic drug appears to be limited.

The clinical pharmacology and antiarrhythmic efficacy of acetylprocainamide in patients with arrhythmias

The actions of acetylprocainamide, the major metabolite of procainamide in man, were studied in a placebo-controlled oral-dose-ranging trial in 16 persons with arrhythmias. The occurrences of arrhythmias decreased in 15 patients receiving acetylprocainamide and increased subsequently in 10 of 13 patients given placebo. The frequency of arrhythmias was reduced by more than 75 percent in nine patients. Antiarrhythmic effects were dependent on dose and serum drug concentrations, with levels of 10 to 24 microgram/ml observed in patients with a reduction of more than 70 percent in premature ventricular complexes. The ratio of preejection period to left ventricular ejection time decreased during therapy. Side effects of light-headedness, insomnia, nausea and diarrhea occurred in six patients at serum levels ranging from 11 to 22 microgram/ml. The serum half-life of acetylprocainamide lengthened from 7 to 21 hours as the creatinine clearance decreased from 105 to 35 ml/min. Acetylprocainamide has antiarrhythmic efficacy, but causes side effects in human beings. This compound appears to contribute to the effects of procainamide therapy and may be useful as an antiarrhythmic drug.