Ultrasound versus fluoroscopy-guided femoral access for percutaneous coronary intervention of chronic total occlusions: Insights from FOUND BLOOD CTO Registry

OBJECTIVE

To compare vascular complications in patients undergoing percutaneous coronary intervention (PCI) of chronic total occlusions (CTO) using ultrasound guidance (USG) versus fluoroscopy guidance (FSG) for femoral access.

BACKGROUND

In patients undergoing PCI, using the arterial femoral access increases the risk of vascular complications compared using the radial access. USG reduces time to access, number of attempts, and vascular complications compared with FSG, but the efficacy of USG has never been tested in the setting of CTO-PCI.

METHODS

A total of 197 patients undergoing CTO-PCI using at least a femoral vascular access from November 2015 to September 2020 were screened. The primary outcome was a composite of local hematoma, pseudoaneurysm, retroperitoneal hemorrhage, arteriovenous fistula or hemoglobin drop ≥3 g/dL during hospitalization. The independent association between USG and the primary outcome of interest was explored.

RESULTS

The primary outcome occurred in 17.3% of patients. Patients in the USG group had a significantly lower incidence of vascular complications compared with patients in the FSG group (8.5% vs. 21.0%, p = 0.039), driven by a reduction of localized hematomas (3.4% vs 13.0%, p = 0.042). After adjustment for type of CTO approach and heparin dose, USG was significantly associated with a reduced relative risk of the composite primary outcome (adjusted odds ratio 0.16, 95% confidence interval 0.05 to 0.51; p = 0.002).

CONCLUSION

USG in CTO-PCI is associated with a decreased risk of vascular complications, primarily driven by a reduction in local hematomas, especially in complex CTO-PCI where the larger use of heparin increases the risk of vascular complications.

Coronary Cannulation After Transcatheter Aortic Valve Replacement: The RE-ACCESS Study

OBJECTIVES

The aims of this study were to investigate the feasibility of coronary ostia cannulation after transcatheter aortic valve replacement (TAVR) and to assess potential predictors of coronary access impairment.

BACKGROUND

Certain data concerning the feasibility and reproducibility of coronary cannulation after TAVR are lacking.

METHODS

RE-ACCESS (Reobtain Coronary Ostia Cannulation Beyond Transcatheter Aortic Valve Stent) was an investigator-driven, single-center, prospective, registry-based study that enrolled consecutive patients undergoing TAVR using all commercially available devices. All patients underwent coronary angiography before and after TAVR. The primary endpoint was the rate of unsuccessful coronary ostia cannulation after TAVR. Secondary endpoints were the identification of factors associated with the inability to selectively cannulate coronary ostia after TAVR.

RESULTS

Among 300 patients enrolled in the RE-ACCESS study from December 2018 to January 2020, a total of 23 cases (7.7%) of unsuccessful coronary cannulation after TAVR were documented. This issue occurred in 22 of 23 cases with the use of Evolut R/PRO transcatheter aortic valves (TAVs) (17.9% vs. 0.4%; p < 0.01). In multivariate analysis, the use of Evolut R/PRO TAVs (odds ratio [OR]: 29.6; 95% confidence interval [CI]: 2.6 to 335.0; p < 0.01), the TAV-sinus of Valsalva relation (OR: 1.1 per 1-mm increase; 95% CI: 1.0 to 1.2; p < 0.01), and the mean TAV implantation depth (OR: 1.7 per 1-mm decrease; 95% CI: 1.3 to 2.3; p < 0.01) were found to be independent predictors of unsuccessful coronary cannulation after TAVR. A model combining these factors was demonstrated to predict with very high accuracy the risk for unsuccessful coronary cannulation after TAVR (area under the curve: 0.94; p < 0.01).

CONCLUSIONS

Unsuccessful coronary cannulation following TAVR was observed in 7.7% of patients and occurred almost exclusively in those receiving Evolut TAVs. The combination of Evolut TAV, a higher TAV-sinus of Valsalva relation, and implantation depth predicts with high accuracy the risk for unsuccessful coronary cannulation after TAVR. (Reobtain Coronary Ostia Cannulation Beyond Transcatheter Aortic Valve Stent [RE-ACCESS]; NCT04026204).

Identification of extracellular vesicles and characterization of miRNA expression profiles in human blastocoel fluid

In this study, for the first time, we demonstrated the presence of microRNAs and extracellular vesicles in human blastocoel fluid. The bioinformatic and comparative analyses identified the biological function of blastocoel fluid microRNAs and suggested a potential role inside the human blastocyst. We found 89 microRNAs, expressed at different levels, able to regulate critical signaling pathways controlling embryo development, such as pluripotency, cell reprogramming, epigenetic modifications, intercellular communication, cell adhesion and cell fate. Blastocoel fluid microRNAs reflect the miRNome of embryonic cells and their presence, associated with the discovery of extracellular vesicles, inside blastocoel fluid, strongly suggests their important role in mediating cell communication among blastocyst cells. Their characterization is important to better understand the earliest stages of embryogenesis and the complex circuits regulating pluripotency. Moreover, blastocoel fluid microRNA profiles could be influenced by blastocyst quality, therefore, microRNAs might be used to assess embryo potential in IVF cycles.

Blood-Brain Barrier in a Haemophilus influenzae Type a In Vitro Infection: Role of Adenosine Receptors A2A and A2B

The blood-brain barrier (BBB) is mainly made up of tightly connected microvascular endothelial cells (BMECs), surrounded by pericytes (BMPCs) which regulate BBB tightness by providing soluble factors that control endothelial proliferation. Haemophilus influenzae type a (Hia) is able to reach the BBB, crossing it, thus causing meningitis. In this study, by using an in vitro model of BBB, performed with human BMECs and human BMPCs in co-culture, we demonstrated that, after Hia infection, the number of hBMPCs decreased whereas the number of hBMECs increased in comparison with non-infected cells. SEM and TEM images showed that Hia was able to enter hBMECs and reduce TEER and VE-cadherin expression. When the cells were infected in presence of SCH58261 and PSB603 but not DPCPX, an increase in TEER values was observed thus demonstrating that A_2A and A_2B adenosine receptors play a key role in BBB dysfunction. These results were confirmed by the use of adenosine receptor agonists CGS21680, CCPA, and NECA. In infected co-cultures cAMP and VEGF increased and TEER reduction was counter-balanced by VEGF-R1 or VEGF-R2 antibodies. Moreover, the phosphorylated CREB and Rho-A significantly increased in infected hBMECs and hBMPCs and the presence of SCH58261 and PSB603 significantly abrogated the phosphorylation. In conclusion, this study demonstrated that the infection stimulated A_2A and A_2B adenosine receptors in hBMECs and hBMPCs thus inducing the pericytes to release large amounts of VEGF. The latter could be responsible for both, pericyte detachment and endothelial cell proliferation, thus provoking BBB impairment.

Risk stratification after ST-segment elevation myocardial infarction

INTRODUCTION

Risk stratification according to the timing of assessment, treatment modality and outcome of interest is highly advisable in patients with ST-elevation myocardial infarction (STEMI) to identify optimal treatment strategies, proper length of hospital stay and correct timing of follow-up. Areas covered: This review is an overview summarizing the characteristics and performance of available risk-scoring systems for STEMI. In particular, we sought to highlight the characteristics of STEMI cohorts used for derivation and validation of the available algorithms and appraise their discrimination ability, calibration and global accuracy. Expert commentary: Applying the appropriate score, customized on patients' profile and clinical characteristics at presentation or during the hospitalization, might prove useful to improve the overall quality of care provided to STEMI patients.

Bioresorbable vascular scaffold in patients with complex coronary artery disease

The advent of fully bioresorbable stent technology is heralded as breakthrough technology in the current era of percutaneous coronary interventions (PCI). Bioresorbable scaffolds (BRS) have the potential to introduce a paradigm shift in interventional cardiology, representing an anatomical and functional "vascular restoration" therapy instead of an artificial stiff tube encased by persistent metallic foreign body. Among BRS, the everolimus-eluting scaffold (ABSORB, Abbott Vascular, Santa Clara, CA, USA) has been the most extensively investigated in clinical studies. The use of ABSORB in the treatment of relatively simple lesions appears to provide a similar degree of safety and efficacy compared with metallic drug-eluting stent (DES) treated under randomized trials conditions, but patients treated in real-world practice are far more complex than those included in randomized trials. Therefore, several ABSORB all-comers registries dealing with real world conditions are being performed. Their currently available results are summarized in the present overview.

How true delivery profile diminution reduces vascular access challenges and complications

Transcatheter aortic valve implantation (TAVI) is the treatment of choice among patients with symptomatic severe aortic stenosis (AS) deemed inoperable and a valuable alternative to surgical aortic valve replacement for high-risk surgical patients. Over the years, this procedure proved to be relatively safe, but despite this complications may occur. When performing TAVI, the most frequent complications are represented by peripheral vascular complications and bleeding involving the access site. Trans-femoral (TF) route is the preferred access site and device evolution has made it possible to reduce in size sheaths and delivery systems from the initial 22- to 24-Fr of the first generation TF devices, progressively down to 18-Fr and then to 16-14-Fr with the latest generations of prostheses, with a required minimal lumen diameter (MLD) of 5.5 mm. The more vascular-friendly TF-TAVI devices, not only have made it possible to patients with small arteries to be treated with this procedure, but also have markedly reduced vascular complications.

Role of cytosolic and calcium independent phospholipases A(2) in insulin secretion impairment of INS-1E cells infected by S. aureus

Cytosolic PLA2 (cPLA2) and Ca(2+)-independent PLA2 (iPLA2) play a significant role in insulin β-cells secretion. Bacterial infections may be responsible of the onset of diabetes. The mechanism by which Staphylococcus aureus infection of INS-1 cells alters glucose-induced insulin secretion has been examined. After acute infection, insulin secretion and PLA2 activities significantly increased. Moreover, increased expressions of phospho-cPLA2, phospho-PKCα and phospho-ERK 1/2 were observed. Chronic infection causes a decrease in insulin release and a significant increase of iPLA2 and COX-2 protein expression. Moreover, insulin secretion in infected cells could be restored using specific siRNAs against iPLA2 isoform and specific COX-2 inhibitor.

Asthenozoospermia and membrane remodeling enzymes: a new role for phospholipase A2

Phosholipase A2 (PLA2 ) activity in the seminal plasma and in sperm heads is closely related to sperm motility and male fertility. Therefore, the purpose of this study was to investigate the possible involvement of different isoforms of phospholipase in asthenozoospermia. To accomplish this, cPLA2 , phospho-cPLA2 , iPLA2 , and sPLA2 were evaluated by immunofluorescence and immunoblot analyses in spermatozoa obtained from 22 normozoospermic men and 28 asthenozoospermic patients. We found significant differences in cPLA2 and its phosphorylated/activated form, iPLA2 , and sPLA2 content and distribution in normal and asthenozoospermic patients. cPLA2 was localized in heads, midpieces, and tails of all spermatozoa as constitutive enzyme, less expressed in the tail of spermatozoa with low progressive motility. While active phospho-cPLA2 distribution was homogeneous throughout the cell body of control-donor spermatozoa, lower levels were detected in the tails of asthenozoospermic patients, as opposed to its strong presence in heads. Low immunofluorescence signal for iPLA2 was found in astenozoospermic patients, whereas sPLA2 was significantly lower in the heads of asthenozoospermic patients. Spermatozoa with low progressive motility showed differences both in terms of total specific activity and of intracellular distribution. cPLA2 , iPLA2 , and sPLA2 specific activities correlated positively and in a significantly manner with sperm progressive motility both in normozoospermic men and asthenozoospermic patients. In conclusion, PLA2 s are expressed in different areas of human spermatozoa. Spermatozoa with low motility showed differences in total specific activity and enzyme distributions. We speculated that PLA2 expression and/or different distribution could be potential biomarkers of asthenozoospermia, one of the major causes of male factor infertility.

AntiClustal: Multiple Sequence Alignment by antipole clustering and linear approximate 1-median computation

In this paper we present a new Multiple Sequence Alignment (MSA) algorithm called AntiClusAl. The method makes use of the commonly use idea of aligning homologous sequences belonging to classes generated by some clustering algorithm, and then continue the alignment process ina bottom-up way along a suitable tree structure. The final result is then read at the root of the tree. Multiple sequence alignment in each cluster makes use of the progressive alignment with the 1-median (center) of the cluster. The 1-median of set S of sequences is the element of S which minimizes the average distance from any other sequence in S. Its exact computation requires quadratic time. The basic idea of our proposed algorithm is to make use of a simple and natural algorithmic technique based on randomized tournaments which has been successfully applied to large size search problems in general metric spaces. In particular a clustering algorithm called Antipole tree and an approximate linear 1-median computation are used. Our algorithm compared with Clustal W, a widely used tool to MSA, shows a better running time results with fully comparable alignment quality. A successful biological application showing high aminoacid conservation during evolution of Xenopus laevis SOD2 is also cited.

Melanosynthesis, differentiation, and apoptosis in Kupffer cells from Rana esculenta

It is well known that amphibian Kupffer cells (KCs) contain eumelanins. In this paper, we demonstrate through a molecular analysis that Rana esculenta KCs synthesize high levels of mRNA for tyrosinase and through cytochemistry that they possess dopa oxidase activity: both these data prove that frog KCs are capable of autonomously synthesizing eumelanins. On the other hand, by using a highly sensitive reverse transcription-polymerase chain reaction assay we clearly show that in mammalian KCs the tyrosinase gene is not expressed. Quite unexpectedly, we have detected tyrosinase mRNA in Rana esculenta spleen, lung, and heart; to explain this finding, we suggest that it could be due to the presence of pigmented macrophages within the spleen, that probably behave as KCs, and of melanophores in lung and heart. It also may be hypothesized that the Rana esculenta tyrosinase gene, as opposed to its mammalian counterpart, is expressed in many cell types because its promoter contains sequences that are recognized by widely synthesized transcription factors. Our experiments also demonstrate that there is an inverse correlation between the amount of tyrosinase mRNA and melanin content, and that populations of terminally differentiated KCs are characterized by a high degree of apoptosis. Based on these data, we propose that differentiating KCs start accumulating eumelanins, as a result of previous expression of high levels of tyrosinase and of dopa oxidase activity, acquire the full KC phenotype (characterized by both phagocytic and melanosynthetic ability), and then undergo apoptosis. Accordingly, we propose that these cells could represent an interesting model to study, at the molecular level, the relationship between differentiation, specific gene expression, and programmed cell death in higher eukaryotes.

Genomic localization of the human genes TAF1A, TAF1B and TAF1C, encoding TAF(I)48, TAF(I)63 and TAF(I)110 subunits of class I general transcription initiation factor SL1

Human SL1 is a general transcription initiation factor (GTF) essential for RNA polymerase I to start rRNA synthesis at class I promoters. It is comprised of the TATA box-binding protein (TBP) and three TBP-associated factors (TAF(I)48, TAF(I)63 and TAF(I)110). We have determined that the human genes TAF1A, TAF1B and TAF1C, encoding these three TAF(I) polypeptides, are localized at lq42, 2p25 and 16q24, respectively. All three genes are present as single copies in the human genome and map to different chromosomes, as shown by somatic cell hybrid panel and radiation hybrid panel analysis and FISH. Two of these genes, TAF1C and TAF1B, are transcribed into multiple RNAs, as determined through Northern analysis of mRNA from various human organs and cell lines. If translated into different polypeptides, this could result in production of variant isoforms of SL1 with different activation potentials.

Characterisation of Kupffer cells in some Amphibia

A study on the Kupffer cells (KCs) of Amphibia was undertaken in order to compare these cells with those of endothermic animals. Liver tissue and isolated and cultured KCs were studied by light microscopy and by transmission and scanning electron microscopy. We have shown that amphibian KCs can be divided into 2 principal types: 'small' and 'large'. Both cell types possess the distinctive KC morphology. They show nonspecific esterase activity, weak endogenous peroxidase activity in the nuclear envelope and in the rough endoplasmic reticulum, and the ability to engulf naturally present cell debris or experimentally administered zymosan or latex particles. The principal difference between the small and the large cells consists in the substantial quantity of inclusion bodies that exist only in the latter. We conclude that amphibian KCs, apart from their ability to build melanosomes and synthesise melanins, are very similar to mammalian KCs.

Genomics of the human genes encoding four TAFII subunits of TFIID, the three subunits of TFIIA, as well as CDK8 and SURB7

By in situ chromosomal hybridization, and by somatic cell and radiation hybrid analysis, we have determined the genomic position of the human genes encoding four TAFII subunits of TFIID (TAFII150, TAFII105, TAFII68, TAFII18), the three subunits of TFIIA (TFIIA35 and TFIIA19, both encoded by the same gene, and TFIIA12), CDK8, and SURB7. All of these proteins are bona fide components of human class II holoenzymes as well as targets of signal transduction pathways that regulate genome expression. The genes encoding them are present in the human genome in a single copy and are localized at 8q23, 18q11.2, 17q11.1-11.2, 1p21, 14q31, 15q21-23, 13q12, and 12p12, respectively. We have mapped all of them to chromosomal regions where hereditary genetic diseases have been localized or which are involved in malignancies, which makes them potential candidates for a causal involvement in these phenotypes.

The amphibian Kupffer cells build and demolish melanosomes: an ultrastructural point of view

This ultrastructural research was carried out to investigate the nature of the liver pigment cells of anuran and caudate amphibians, the pattern of melanosome ontogenesis, and the demolition processes of old melanosomes. We demonstrate that these liver pigment cells are able to internalize zymosan particles and latex beads; therefore, being professional phagocytes, they, as liver resident macrophages, can be classified as Kupffer cells (KCs). They show "melanosomogenesis centers" in which several maturation stages of premelanosomes are visible; the premelanosomes are formed by two principal components: a filamentous structure that will constitute the "inner" area of the melanosome and a vesicular component, budding from the Trans Golgi Network and that carries enzymes, which will constitute the "cortical area" of the melanosome. Thus the KCs, thanks to the presence of the "melanosomogenesis centers," are also melanosome producing cells. They are also able to demolish melanosomes by heterophagocytosis and, probably, also by autophagocytosis. In conclusion, we propose a classification of vertebrate pigment cells.

Melanins in physiological conditions protect against lipoperoxidation. A study on albino and pigmented Xenopus

The susceptibility to lipoperoxidation in liver of albino and pigmented Xenopus laevis Daudin, has been studied. Albino Xenopus liver was richer in polyunsaturated fatty acids (PUFAs) than the pigmented one; moreover, it was also richer in mitochondrial superoxide dismutase (MnSOD) and in reduced glutathione (GSH). The thiobarbituric acid-reactive substances (TBARS) values were more abundant in the albino tissue compared to the pigmented tissue both during spontaneous and Fe++ induced lipoperoxidation. Therefore, when isolated and purified melanin, in physiological quantities, was added to albino tissue, the TBARS values drastically decreased. Thus, melanin, in our experimental conditions, protects the albino tissue even more than SOD and GSH do. Melanin, in our opinion, acts as an antioxidant, because it is able to scavenge O2-.

In vitro scavenger activity of some flavonoids and melanins against O2-(.)

The scavenger activity against O2-. of some flavonoids and melanins (synthetic melanins and melanins isolated from animal tissues, vegetable seeds, and mushroom spores) has been studied by ESR spectrometry. All these substances, except flavon and flavanone, diminish the signal of O2-. generated in vitro by a system containing H2O2 and acetone in an alkaline medium. It is shown that the presence of hydroxyl groups in the B ring of flavonoids is essential for their scavenger activity. Moreover, the presence of a hydroxyl at C-3 enhances the scavenger ability of flavonoids. Generally, aglycons are more active than their glycosides. It seems plausible that the antioxidant property of these substances comes from their scavenger activity against O2-(.). It is also pointed out that the scavenger activity shown by melanins, is strictly correlated with their nature of stable free radical.

Lipid peroxidation in pigmented and unpigmented liver tissues: protective role of melanin

The protective role of melanin as an antioxidant biopolymer against lipid peroxidation was investigated. In pigmented frog liver and in albino rat liver the following were tested: thiobarbituric acid (TBA) reactive material (to show the induced lipoperoxidation in vitro), fatty acids, and reduced glutathione content. Our results show that susceptibility to the in vitro lipoperoxidation induced by ferrous ions is lower in the tissue containing melanin, though the content of the polyunsaturated fatty acids is higher in pigmented than in unpigmented tissues and reduced glutathione levels are lower in pigmented tissue. Our data support the hypothesis that melanin could reduce lipoperoxidation in pigmented tissue.

Circannual rhythm of the melanin content in frog liver (Rana esculenta L.)

The melanin content of Rana esculenta L. liver varies according to a circannual statistically significant rhythm, as shown by variance and single cosinor analysis. The maximum is found in autumn-winter, the minimum in spring-summer. The linear regression analysis shown a negative correlation between the amount of melanin and the environmental temperature.

Antioxidant enzymatic systems in pigment tissue of amphibia

Superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities in pigmented and unpigmented liver tissues of frog and albino rat, respectively, were studied. Our results show that pigmented tissue is lacking in manganese superoxide dismutase activity and that the main enzymatic activity utilized in the cytosol by pigmented cells to reduce the hydrogen peroxide to water is represented by catalase; on the contrary, for the same reaction, the cells of albino rat liver primarily utilize the glutathione peroxidase activity. Both a low glutathione peroxidase activity and a low glutathione reductase activity were found in pigmented tissue of frog liver when compared with unpigmented tissue of rat liver. In light of our results, we also report a hypothetical interrelationship between melanin and reduced glutathione: We believe that in pigmented cells the melanin could act as a reducing physiological agent replacing the glutathione in the reduction of hydrogen peroxide. This reducing action of melanin could cause a diminished need for GSH and therefore could provoke the low glutathione peroxidase and reductase activities in pigmented tissue.

Melanosomes from liver and skin of Rana esculenta L. A comparative chemical study

1. Melanosomes from skin and liver of Rana esculenta L. have been isolated and some chemical properties of the relevant melanin and protein components were compared. 2. In both cases the pigments show spectroscopic (ESR) and chemical characteristics similar to those of eumelanins. The melanin content in skin melanosomes is higher than in the liver counterparts. 3. Amino acid patterns of the two protein components are different in their quantitative composition and both are characterized by high levels of glycine and proline. 4. The results as a whole indicate that skin and liver melanosomes from the same animal markedly differ in their chemical composition.

Relationship between melanin content and superoxide dismutase (SOD) activity in the liver of various species of animals

The scavenger effect of melanin and of superoxide dismutase (SOD) activity on superoxide anion has been shown. In this work we show the relationship between melanin content and SOD activity in livers containing different quantities of melanin which were taken from various species of animals. The mitochondrial SOD activity disappears when the melanin content in the liver is very high; moreover it increases, in the liver of various species of animals examined, proportionally to the decrease of melanin content. No significant variation of the SOD activity localized in the soluble fraction has been detected when related to the melanin content. We think that in the pigmented liver the antioxidant activity of the melanin could mimic part of the function of SOD. The loss of Mn SOD activity could be mediated by a low intracellular level of superoxide anion due to the scavenger effect of melanin on superoxide anion; in fact, it is well known that the biosynthesis of Mn SOD is induced by intracellular levels of superoxide anion.

Effects of vitamin A in the presence of vitamins D3, E, K1 on red cell membrane structure

The incubation of erythrocyte ghosts with mixtures of vitamins A+D3, A+E, A+K1 produces decrease or increase of fluorescence anisotropy r of the DPH probe, depending on the vitamin/vitamin ratio. We found a correlation between the order parameter S and cell fusion phenomena observed by phase contrast microscopy.

[Heavy metal concentrations in various species fished from the Gulf of Catania]

The AA report the concentrations of Cu, Zn, Cd, Pb and Hg found in fish, crustaceans and mollusca fished in a zone of the coast to the south of the city of Catania. The results obtained show that among the fish the species with the highest concentrations of all the metals investigated, but excluding mercury, is Boops boops (bogue) followed by Trachurus mediterraneus (horse mackerel), whereas the species showing least concentrations is Pagellus erythrinus (pandora). In many cases the concentrations of individual metals in our findings are higher than those given in the literature for the same species fished in other waters.

[Application of the biotic index and the diversity index to the study of macro-benthons in a river]

Using the Biotic Index and the Diversity Index the results are analysed of a study of the macrobenthic community sampled in the course of one year at three stations along he lowest-lying stretch of the River Simeto. The results obtained from applying the two different indices are not in perfect agreement one with the other. Whereas with the Biotic Index one could be led to consider the fluvial environment situation a good one, the Diversity Index shows the environment to be partially compromised by organic substances. On the basis of results of chemico-physico-microbiological analyses as well as data concerning the nutritive habits of the species found, we conclude that the Diversity Index is a more suitable instrument for measuring the biological reality of the Simeto.

[Study of factors influencing the changes in liver melanin content of amphibia. II. Effect of fasting]

Statistical examination of the data from experiments conducted on groups of Amphibians induces us to retain as plausible the hypothesis which indicates in fasting one of the preminent factors that cause an increase in the melanic content of their liver. The temperature does not act directly, but indirectly, on the process of melanosynthesis, by inducing or otherwise the semilethargous state on which alimentation depends.