Two-hit Theory Research Articles

Overlap syndrome: a case series and literature review of concurrent pigment dispersion and pseudoexfoliation syndromes.

The purpose of this review is to present two cases of overlap syndrome, or concurrent pigment dispersion syndrome and pseudoexfoliation syndrome. The summary of existing literature highlights the importance of accurate diagnosis and potential treatment options of overlap syndrome. The cases describe two patients with overlap syndrome and resulting progressive glaucoma. The condition tends to present after age 50 years old, with presence of both pseudoexfoliative material and pigment dispersion signs. The pigment dispersion syndrome may be quiescent at the time of pseudoexfoliation onset and may have gone undiagnosed. This form of glaucoma poses challenges in controlling intraocular pressure and may progress rapidly, often requiring surgical intervention. This paper reviews the common examination findings of pigment dispersion syndrome and pseudoexfoliation, which may aid clinicians in the diagnosis of the rare condition, overlap syndrome. The connection between the two conditions remains unclear, though studies of possible genetic associations are underway. The two-hit theory, or initial damage to the trabecular meshwork increasing susceptibility to future damage, is plausible given the severe nature of the condition. Though definitive conclusions regarding treatment strategies and outcomes of overlap syndrome are lacking, increased awareness, diagnosis, and study of the condition may help guide the management of overlap syndrome.

ROLE OF CASPASE-1/CASPASE-11-HMGB1-RAGE/TLR4 SIGNALING IN THE EXACERBATION OF EXTRAPULMONARY SEPSIS INDUCED LUNG INJURY BY MECHANICAL VENTILATION.

Mechanical ventilation (MV) is a clinically important measure for respiratory support in critically ill patients. Although moderate tidal volume MV does not cause lung injury, it can further exacerbate lung injury in pathological state such as sepsis. This pathological process is known as the 'two-hit' theory, whereby an initial lung injury (e.g., infection, trauma, or sepsis) triggers an inflammatory response that activates immune cells, presenting the lung tissue in a fragile state and rendering it more susceptible to subsequent injury. The second hit occurs when mechanical ventilation is applied to lung tissue in a fragile state, and it is noteworthy that this mechanical ventilation is harmless to healthy lung tissue, further aggravating pre-existing lung injury through unknown mechanisms. This interaction between initial injury and subsequent mechanical ventilation develops a malignant cycle significantly exacerbating lung injury and severely hampering patient prognosis. The two-hit theory is critical to understanding the complicated mechanisms of ventilator-associated lung injury and facilitates the subsequent development of targeted therapeutic strategies. CLP mice model was used to mimic clinical sepsis patients. After 12 hours the mice were mechanical ventilated for 2-6 hours. MV by itself didn't lead to HMGB1 release, but significantly strengthened HMGB1 in plasma and cytoplasm of lung tissue in septic mice. Plasma and lung tissue activation of cytokines and chemokines, MAPK signaling pathway, neutrophil recruitment, and ALI were progressively decreased in LysM HMGB1-/- (Hmgb1 deletion in myeloid cells) and iHMGB1-/- mice (inducible HMGB1-/- mouse strain where the Hmgb1 gene was globally deleted after tamoxifen treatment). Compared with C57BL/6 mice, although EC-HMGB1-/- (Hmgb1 deletion in endothelial cells) mice didn't have lower levels of inflammation, neutrophil recruitment and lung injury were reduced. Compared with LysM HMGB1-/- mice, EC-HMGB1-/- mice had higher levels of inflammation but significantly lower neutrophil recruitment and lung injury. Overall, iHMGB1-/- mice had the lowest levels of all the above indicators. The level of inflammation, neutrophil recruitment and the degree of lung injury were decreased in RAGE-/- mice, and even the above indices were further decreased in TLR4/RAGE-/- mice. Levels of inflammation and neutrophil recruitment were decreased in Caspase-11-/- and Caspase-1/11-/- mice, but no statistical difference between these two gene knockout mice. These data show for the first time that the Caspase-1/Caspase-11-HMGB1-TLR4/RAGE signaling pathway plays a key role in mice model of sepsis induced lung injury exacerbated by MV. Different species of HMGB1 knockout mice have different lung protective mechanisms in the 'two hits' model, and location is the key to function. Specifically, LysM HMGB1-/- mice due to the deletion of HMGB1 in myeloid cells resulted in a pulmonary protective mechanism that was associated with a downregulation of the inflammatory response. EC HMGB1-/- mice are deficient in HMGB1 owing to endothelial cells, resulting in a distinct pulmonary protective mechanism independent of the inflammatory response and more relevant to the improvement of alveolar-capillary permeability. iHMGB1-/- mice, which are systemically HMGB1-deficient, share both of these lung-protective mechanisms.

Abstract 23: Development of a biallelicDicer1mutant mouse strain for studying the pathogenesis of DICER1 syndrome-associated cancer

Abstract DICER1 encodes a RNase III enzyme that post-transcriptionally controls gene expression through governing microRNA (miRNA) biogenesis. We and others have demonstrated that somatic mutations of DICER1 at its RNase IIIb domain metal binding sites, impairing its capability to produce mature miRNAs from the 5P strand of miRNA precursors, occur recurrently in a broad spectrum of cancers associated with the DICER1 syndrome that affects children and youths predominantly. The biallelic DICER1 mutations in these cancers challenge the two-hit hypothesis theory of traditional tumour suppressors, but it remains unproven whether these mutations are sufficient to drive tumorigenesis. The lack of biology relevant preclinical models has also hindered the understanding the pathogenesis. Here, we developed a genetically engineered mouse strain that expresses an inducible knockin Dicer1 missense mutation (Dicer1+/fl-D1693N), equivalent to the DICER1 RNase IIIb hotspot mutation D1709N in human cancers. This conditional strain behaves as a null allele due to an aberrant splicing event without Cre-mediated recombination. When crossed with a well-characterized conditional null Dicer1 strain (Dicer1fl/fl), the resulting compound heterozygous strain (Dicer1fl/fl-D1693N), acts as a hemizygous wildtype allele that is converted to a hemizygous missense mutation allele upon Cre-mediated recombination, reflecting the genetic status of DICER1 in DICER1 syndrome-associated cancer. When crossing with the anti-Mullerian hormone receptor 2 (Amhr2) driven cre strain (Amhr2+/cre), the biallelic Dicer1 mutation resulted in infertility in females by impairing the development of oviduct and endometrium and ultimately drove the development of multicystic tubal and intra-uterine tumours. Histologically, these murine tumors resemble human Müllerian adenosarcoma and other DICER1 syndrome-associated sarcomas. Molecular analysis of these murine tumours validated the miRNA biogenesis defects in 5P-miRNA production, uncovered the activation of the myc signaling and identified that loss of let-7 family miRNAs may drive the transcriptomic rewiring and malignant transformation. Thus, this first DICER1 syndrome-associated murine cancer model faithfully recapitulates the biology of human cancer and provides a unique tool for future investigation and therapeutic development. Citation Format: Yemin Wang, Shary Chen, Janine Senz, Maxwell Douglas, Shelby Thornton, Yana Moscovitz, C. Blake Gilks, David Huntsman, Gregg Morin. Development of a biallelicDicer1mutant mouse strain for studying the pathogenesis of DICER1 syndrome-associated cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 23.

Early total care to early appropriate care - What every anesthesiologist must know!

Orthopedic trauma is one of the commonest injuries necessitating surgical intervention in a trauma patient. The management protocols in such severely injured orthopedic patients have evolved from conservative treatment to 'early total care' (ETC) to 'damage control orthopedics' (DCO) and recently to 'early appropriate care' (EAC)/'safe definitive surgery' (SDS). 'DCO' involves emergent, basic minimum life- or limb-saving surgery with continued resuscitation and definitive fixation of fractures being done later, once the patient has been resuscitated and stabilized. An insight into the immunological processes at a molecular level evoked in a poly-traumatized patient led to the evolution of the 'two-hit theory;' 'first hit' being the injury itself while the 'second hit' caused by the surgical trauma. As the 'two-hit theory' gained popularity, it led to a delay of definitive surgery for 2-5 days following trauma, since a higher complication rate was observed following definitive surgery within the first 5 days of the injury. This is a review article on the historical perspectives of DCO, immunological mechanisms involved, and various injuries requiring damage control approach or EAC/ETC and their anesthetic management.

In Memoriam: Beatrice Mintz, PhD (1921–2022)

In Memoriam: Beatrice Mintz, PhD (1921–2022)

The two-hit theory hits 50.

Few ideas in cancer genetics have been as influential as the “two-hit” theory of tumor suppressors. This idea was introduced in 1971 by Al Knudson in a paper in the Proceedings of the National Academy of Science and forms the basis for our current understanding of the role of mutations in cancer. In this theoretical discussion proposing a genetic basis for retinoblastoma, a childhood cancer of the retina, Knudson posited that these tumors arise from two inactivating mutations, targeting both alleles of a putative tumor suppressor gene. While this work built on earlier proposals that cancers are the result of mutations in more than one gene, it was the first to propose a plausible mechanism by which single genes that are affected by germ-line mutations in heritable cancers could also cause spontaneous, nonheritable tumors when mutated in somatic tissues. Remarkably, Knudson described the existence and properties of a retinoblastoma tumor suppressor gene a full 15 years before the gene was cloned.

O24 Malignancy in antiphospholipid syndrome: a catastrophe

O24 Malignancy in antiphospholipid syndrome: a catastrophe

Whole exome sequencing and system biology analysis support the "two-hit" mechanism in the onset of Ameloblastoma.

Background Ameloblastoma is the most frequent odontogenic tumor. Various evidence has highlighted the role of somatic mutations, including recurrent mutation BRAF V600E, in the tumorigenesis of Ameloblastoma, but the intact genetic pathology remains unknown. Material and Methods We sequenced the whole exome of both tumor tissue and healthy bone tissue from four mandibular ameloblastoma patients. The identified somatic mutations were integrated into Weighted Gene Co-expression Network Analysis on publicly available expression data of odontoblast, ameloblast, and Ameloblastoma. Results We identified a total of 70 rare and severe somatic mutations. We found BRAF V600E on all four patients, supporting previous discovery. HSAP4 was also hit by two missense mutations on two different patients. By applying Weighted Gene Co-expression Network Analysis on expression data of odontoblast, ameloblast, and Ameloblastoma, we found a proliferation-associated gene module that was significantly disrupted in tumor tissues. Each patient carried at least two rare, severe somatic mutations affecting genes within this module, including HSPA4, GNAS, CLTC, NES, and KMT2D. All these mutations had a ratio of variant-support reads lower than BRAF V600E, indicating that they occurred later than BRAF V600E. Conclusions We suggest that a severe somatic mutation on the gene network of cell proliferation other than BRAF V600E, namely second hit, may contribute to the tumorigenesis of Ameloblastoma. Key words:Ameloblastoma, whole exome sequencing, somatic mutation, BRAF, HSPA4, two-hit theory.

S168. THE ASSOCIATION BETWEEN MMP-9 AND CHOROID PLEXUS VOLUME IN SCHIZOPHRENIA

BackgroundSchizophrenia (SCZ) is a severe and chronic brain disorder that affects about 1% of the world population. It is among the most burdensome illnesses with a serious impact on patients, their families and society.To this day, a lot remains unknown about the neuropathological cause and etiology of SCZ.The prominent two-hit theory postulates that early neurodevelopmental abnormalities interact with a later “second hit” which occurs around symptom onset. Recent research points towards the role of inflammation in pathophysiology of schizophrenia.Matrix metalloproteinase-9 (MMP-9) was recently suggested as a potential key player in both first and second “hit” in the pathology of SCZ. It is considered to not only regulate brain development and synaptic plasticity, but to also mediate neuroinflammation. A point of interest for interaction with neuroinflammatory pathways is the Choroid Plexus (ChP). MMP-9 has been reported to be upregulated in ChP in SCZ. Since ChP regulates CSF production and permeability of the blood-CSF-barrier, MMP-9 upregulation in ChP might lead to its enlargement, as well as enlargement of the lateral ventricles and increased extracellular water volume, all found previously in SCZ. We investigate, for the first time, the relationship between MMP-9 blood plasma concentration and volume of ChP in patients with SCZ compared to healthy controls (HC).MethodsWe included 66 subjects (25 female = 38%, 41 male = 62%, mean age 32.59 +/- 9.14 years); 32 were patients with SCZ, 34 were HC.ELISA analysis was performed to measure MMP-9 blood concentrations in patients and HC.A whole brain, high-resolution three-dimensional T1-weighted magnetization prepared rapid gradient echo (MPRAGE) sequence scan was used to collect 240 sagittal slices, field of view = 224 x 224 mm2, 1 mm3 isotropic voxel, TR = 2.3 s, TE = 2.33 ms, flip angle = 8° on a 3T Siemens Magnetom Prisma.Structural T1 images underwent visual quality control, were realigned and parcellated into 176 gray and white matter regions using FreeSurfer software.Preliminary analyses were conducted comparing 1) MMP-9 levels between groups and 2) relating MMP-9 levels to ChP volume utilizing regression analyses.ResultsPatients with SCZ showed a strong upregulation of MMP-9 compared to HC (patients: 120 ± 60 ng/ml; HC: 60 ± 40 ng/ml; p < 0.0001). Furthermore, linear regression analyses - corrected for age and sex - demonstrated a positive association between concentration of MMP-9 and ChP volumes (left: R2 = .095, p < .01; right: R2 = .084, p < .02).DiscussionTo our knowledge, our study is the first to present preliminary evidence of an association between brain structure and MMP-9 peripheral upregulation in SCZ.Advanced evaluation of MMP-9 might enhance our understanding of illness cause, enable outcome predictions and paint the way for more individualized psychopharmacotherapy, as MMP-9 might serve as potential pharmacological target.However, further analyses are needed to validate our findings using as neuroanatomically precise methods as possible and to develop MMP-9 biomarkers that would capture central, as opposed to peripheral levels of MMP-9.

Evidence for immortality and autonomy in animal cancer models is often not provided, which causes confusion on key issues of cancer biology.

Modern research into carcinogenesis has undergone three phases. Surgeons and pathologists started the first phase roughly 250 years ago, establishing morphological traits of tumors for pathologic diagnosis, and setting immortality and autonomy as indispensable criteria for neoplasms. A century ago, medical doctors, biologists and chemists started to enhance “experimental cancer research” by establishing many animal models of chemical-induced carcinogenesis for studies of cellular mechanisms. In this second phase, the two-hit theory and stepwise carcinogenesis of “initiation-promotion” or “initiation-promotion-progression” were established, with an illustrious finding that outgrowths induced in animals depend on the inducers, and thus are not authentically neoplastic, until late stages. The last 40 years are the third incarnation, molecular biologists have gradually dominated the carcinogenesis research fraternity and have established numerous genetically-modified animal models of carcinogenesis. However, evidence has not been provided for immortality and autonomy of the lesions from most of these models. Probably, many lesions had already been collected from animals for analyses of molecular mechanisms of “cancer” before the lesions became autonomous. We herein review the monumental work of many predecessors to reinforce that evidence for immortality and autonomy is essential for confirming a neoplastic nature. We extrapolate that immortality and autonomy are established early during sporadic human carcinogenesis, unlike the late establishment in most animal models. It is imperative to resume many forerunners' work by determining the genetic bases for initiation, promotion and progression, the genetic bases for immortality and autonomy, and which animal models are, in fact, good for identifying such genetic bases.

Astaxanthin Attenuates Hepatic Damages and Mitochondrial Dysfunction in Nonalcoholic Fatty Liver Disease by Regulating the FGF21/PGC-1α Pathway

Backgrounds: Non-alcoholic fatty liver disease(NAFLD) is considered to be one of the most common chronic liver diseases across worldwide. The pathogenesis of NAFLD is described as the two-hit theory. However, the underlying mechanisms remains to be fully explored. Beneficial effects of astaxanthin(Ax) have been identified,including anti-oxidative, anti-inflammatory, and anti-tumor activity. The present study aimed to elucidate the protective effect of Ax against NAFLD and its underlying mechanism. Methods: Mice were fed either a high fat or control diet, with or without AX, for up to 12 weeks. L02 cells were treated with free fatty acids combined with different doses of Ax for 48 h. Histopathology, expression of lipid metabolism, inflammation, apoptosis, and fibrosis-related genes were assessed. Findings: The results indicated that Ax attenuated HFD- and FFA-induced lipid accumulation and its associated oxidative stress, cell apoptosis, inflammation, and fibrosis both in vivo and in vitro. Ax upregulated FGF21 and PGC-1α expression in damaged hepatocytes, which suggested an unrecognized mechanism of Ax on ameliorating NAFLD. Interpretation: Ax attenuated hepatocyte damage and mitochondrial dysfunction in NAFLD by upregulating FGF21/PGC-1α.Our studies verified that Ax may become a promising drug to treat or relieve NAFLD. Funding: Work was supported by the National Natural Science Foundation of China (NO: 81670472, 81700502 and 81800538); National Natural Science Foundation of Shanghai (NO: 19ZR1447700); the Health System Innovation Plan of Shanghai Putuo District Science and Technology Committee (NO: PTKWWS2018001); the WBN Liver Disease Research Fund of China Hepatitis Prevention Foundation (NO: CFHPC2019031); the Yangfan Plan of Shanghai Science and Technology Commission (NO: 2018YF1420000); the Project of Shanghai Health Commission (NO: 2019469). Declaration of Interest: The authors have declared that no competing interest exists. Ethical Approval: Experimental protocols were approved by the Animal Care and Use Committee of Shanghai Tongji University, China. All animal experiments were carried out according to the guidelines of the China National Institutes of Health. All efforts were made to minimize suffering of experimental mice in this research.

Combination of the Hansemann-Boveri, Warburg, and Knudson Theories of Cancer, Based on Failure of Missegregation Damage Mitigation

The Hansemann-Boveri aneuploidy theory, the Warburg aerobic glycolysis theory, and the Knudson two-hit mutation theory can be seen as different aspects of a theory where the very common chromosome missegregation damage is mitigated by several quite different mechanisms. Cancer only occurs when all of these mechanisms have been inactivated in a single cell line, typically by mutation, for example by carcinogens. There are at least 5 different repair mechanisms which implies a multiple hit factor of at least 5. The repairs are: Tetraploidization instead of missegregation, cell division arrest, apoptosis, elimination by the immune system, and prevention of long life of cancer cell/macrophage fusions. Hansemann-Boveri aneuploidy is caused by run-away missegregation, Warburg aerobic glycolysis by mutational inactivation of the mitochondrial apoptosis mechanism, and the Knudson two-hit is a subclass of the multiple hit mechanism.

Distinct Incidence of Takotsubo Syndrome Between Amyotrophic Lateral Sclerosis and Synucleinopathies: A Cohort Study.

Takotsubo syndrome (TTS) is an acute cardiac syndrome characterized by regional left ventricular dysfunction with a peculiar circumferential pattern, which typically results in apical ballooning. Evidence indicates a pivotal role of catecholamines in TTS, and researchers have discussed multiple hypotheses on the etiology, including multivessel coronary spasm, myocardial stunning, excessive transient ventricular afterload, and cardiac sympathetic overactivity with local noradrenaline spillover. Although central nervous system disorders, such as stroke and epilepsy, are known to trigger TTS, the incidence and clinical features of TTS in neurodegenerative disorders are poorly understood. Here, we retrospectively examined TTS cases in a single-center cohort composed of 250 patients with amyotrophic lateral sclerosis (ALS) and 870 patients with synucleinopathies [582 patients with Parkinson's disease (PD), 125 patients with dementia with Lewy bodies (DLB), and 163 patients with multiple system atrophy (MSA)] and identified 4 (1.6%, including 2 women) cases with ALS and no cases with synucleinopathies. Two ALS patients underwent autopsy and the pathological findings were compatible with the chronological changes identified in catecholamine-induced cardiomyopathy. A literature review identified 16 TTS cases with ALS, 1 case each with PD and DLB, and no cases with MSA. When current and previous TTS cases with ALS were concatenated: 55% (11/20) were female; 35% (7/20) had a bulbar-onset and 45% (9/20) had a limb-onset; the mean age of TTS onset was 63.3 ± 9.0 years and the mean interval time from ALS onset to TTS development was 4.9 ± 3.0 years; no (0/16) patients developed TTS within 12 months after ALS onset; 50% (10/20) underwent artificial ventilations; the mortality was 17% (3/18); and most cases had precipitating factors, and TTS development was associated with gastrostomy, tracheostomy, or infections in 45% (9/20) of the patients. This study demonstrated that ALS is a considerable predisposing factor of TTS and that synucleinopathies rarely cause TTS. The distinct TTS incidence between ALS and synucleinopathies may be due to cardiac sympathetic overactivity in ALS and may also be affected by cardiac sympathetic denervation in synucleinopathies. Moreover, the etiology of TTS in ALS may be reasonably explained by the two-hit theory.

Loss of Heterozygosity in BRCA1 and BRCA2 Genes in Patients with Ovarian Cancer and Probability of Its Use for Clinical Classification of Variations.

Changes (or variants) in BRCA1 and BRCA2 gene sequences can have different lengths and clinical significance: from single nucleotide variants (SNV) and short insertions/deletions (<50 bp) to extended deletions and duplications (so-called copy number variations, or CNV). According to their clinical significance, all variants can be divided into pathogenic, likely pathogenic, variants of uncertain significance, likely benign, and benign. Moreover, variants can be germinal (i.e. inherited from parents) and somatic (arising in the process of development of the organism). A specific somatic event is loss of heterozygosity (LOH), i.e. transition of one or many point and short variants from heterozygous to homozygous state. Such an event can be the key to the development of carcinogenesis for cells carrying a pathogenic variant, if we consider it within the framework of the Knudson's two-hit carcinogenesis theory. We studied the prevalence and nature of LOH in of ovarian cancer samples carrying or not carrying a pathogenic variant. To this end, a full coding sequence of BRCA1/2 genes was determined in 30 pairs of DNA samples isolated from blood cells and paraffinized histological blocks of patients on a MiSeq Illumina instrument. Analyss of the obtained reads revealed 9 pathogenic point and short variants (30% patients): 6 germinal (20%) and 3 somatic (10%), and 8 somatic CNV (3 deletions and 5 duplications of several or all exons of the BRCA1 gene). LOH was detected in 70% patients; among the carriers of pathogenic variants - in 83%. For pathogenic variants, the percentage of reads with the alternative allele increased more often than for benign variants located in another gene, or detected in other patients (67% vs. 44%). However, the difference was statistically insignificant, which can be due to insufficient number of patients. Only in 3 of 21 cases of LOH (14%), it can be attributed to CNV. In other cases, LOH is most likely determined by gene conversion, but further research is needed.

Diagnosis &amp; Treatment of Retinoblastoma: Current Review

Retinoblastoma is a rare disease, but most common tumor which arises in eye. It can affect one or both eyes, and the main pathophysiology is explained by the “Two-hit theory” − the germline mutation of the RB1 gene. Most common clinical symptoms are leuocoria, strabismus, poor visual tracking, glaucoma, and orbital cellulitis. Diagnosis is made by ophthalmologist through fundoscopic examination; Examination under General Anesthesia (EUA) is recommended until the age 3. Orbital CT and MRI can detect the tumor invasion on optic nerve, central nervous system. CSF studies, examination of bone is helpful if the distant metastasis is suspected. Biopsy is rarely done unless in the case of enucleation. Enucleated eye should be explored for the invasion to the optic nerve, choroid, anterior chamber, iris and pupil. Treatment strategies can be different according to the disease status. If the single eye is involved, the treatment goal will be the removal of tumor and prevention of relapse. Local therapies include cryotherapy, laser photocoagulation, thermotherapy can be the choice, and if the tumor is too large for the local therapy, enucleation should be concerned. Nowadays, chemo-reduction combined with local therapy, intra-arterial and intravitreous chemotherapeutic agent injections are studied to avoid enucleation. In bilateral retinoblastoma, multidisciplinary treatments include chemoreduction, external beam radiotherapy, local therapy and other experimental therapies are needed: like intra-arterial injection, intra-vitreal injection, and high-dose chemotherapy with autologous stem cell transplantation. Early detection of retinoblastoma is important to save the vision and eyeball.

Encapsulating peritoneal sclerosis-a rare but devastating peritoneal disease.

Encapsulating peritoneal sclerosis (EPS) is a devastating but, fortunately, rare complication of long-term peritoneal dialysis. The disease is associated with extensive thickening and fibrosis of the peritoneum resulting in the formation of a fibrous cocoon encapsulating the bowel leading to intestinal obstruction. The incidence of EPS ranges between 0.7 and 3.3% and increases with duration of peritoneal dialysis therapy. Dialysis fluid is hyperosmotic, hyperglycemic, and acidic causing chronic injury and inflammation in the peritoneum with loss of mesothelium and extensive tissue fibrosis. The pathogenesis of EPS, however, still remains uncertain, although a widely accepted hypothesis is the “two-hit theory,” where, the first hit is chronic peritoneal membrane injury from long standing peritoneal dialysis followed by a second hit such as an episode of peritonitis, genetic predisposition and/or acute cessation of peritoneal dialysis, leading to EPS. Recently, EPS has been reported in patients shortly after transplantation suggesting that this procedure may also act as a possible second insult. The process of epithelial–mesenchymal transition of mesothelial cells is proposed to play a central role in the development of peritoneal sclerosis, a common characteristic of patients on dialysis, however, its importance in EPS is less clear. There is no established treatment for EPS although evidence from small case studies suggests that corticosteroids and tamoxifen may be beneficial. Nutritional support is essential and surgical intervention (peritonectomy and enterolysis) is recommended in later stages to relieve bowel obstruction.

Glutamine attenuates acute lung injury caused by acid aspiration.

Inadequate ventilator settings may cause overwhelming inflammatory responses associated with ventilator-induced lung injury (VILI) in patients with acute respiratory distress syndrome (ARDS). Here, we examined potential benefits of glutamine (GLN) on a two-hit model for VILI after acid aspiration-induced lung injury in rats. Rats were intratracheally challenged with hydrochloric acid as a first hit to induce lung inflammation, then randomly received intravenous GLN or lactated Ringer’s solution (vehicle control) thirty min before different ventilator strategies. Rats were then randomized to receive mechanical ventilation as a second hit with a high tidal volume (TV) of 15 mL/kg and zero positive end-expiratory pressure (PEEP) or a low TV of 6 mL/kg with PEEP of 5 cm H2O. We evaluated lung oxygenation, inflammation, mechanics, and histology. After ventilator use for 4 h, high TV resulted in greater lung injury physiologic and biologic indices. Compared with vehicle treated rats, GLN administration attenuated lung injury, with improved oxygenation and static compliance, and decreased respiratory elastance, lung edema, extended lung destruction (lung injury scores and lung histology), neutrophil recruitment in the lung, and cytokine production. Thus, GLN administration improved the physiologic and biologic profiles of this experimental model of VILI based on the two-hit theory.

Encomium: Giovanni Neri—Polyhedral and down‐to‐earth mentor

Encomium: Giovanni Neri—Polyhedral and down‐to‐earth mentor

Effects of Somatic Mutations Are Associated with SNP in the Progression of Individual Acute Myeloid Leukemia Patient: The Two-Hit Theory Explains Inherited Predisposition to Pathogenesis

This study evaluated the effects of somatic mutations and single nucleotide polymorphisms (SNPs) on disease progression and tried to verify the two-hit theory in cancer pathogenesis. To address this issue, SNP analysis was performed using the UCSC hg19 program in 10 acute myeloid leukemia patients (samples, G1 to G10), and somatic mutations were identified in the same tumor sample using SomaticSniper and VarScan2. SNPs in KRAS were detected in 4 out of 10 different individuals, and those of DNMT3A were detected in 5 of the same patient cohort. In 2 patients, both KRAS and DNMT3A were detected simultaneously. A somatic mutation in IDH2 was detected in these 2 patients. One of the patients had an additional mutation in FLT3, while the other patient had an NPM1 mutation. The patient with an FLT3 mutation relapsed shortly after attaining remission, while the other patient with the NPM1 mutation did not suffer a relapse. Our results indicate that SNPs with additional somatic mutations affect the prognosis of AML.

Association Between Appendectomy and Fibrosis Progression in Nonalcoholic Fatty Liver Disease.

BackgroundA two-hit theory explaining the progression of nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH) and fibrosis is widely accepted. Endotoxins entering the portal vein from the gut are thought to be one cause of this second hit, and the literature frequently mentions associations between gut-derived endotoxins and progression of fibrosis in NAFLD. The appendix regulates intestinal immunity to protect the gut from the invasion of bacteria and antigens. Appendectomy may thus contribute to progression of fibrosis in NAFLD, but this association has not yet been clarified. We therefore investigated the association between appendectomy and progression of fibrosis in NAFLD.MethodsFifty two patients with NAFLD who underwent liver biopsy in our department were included in this study. Based on Brunt’s scores, patients with NAFLD were classified into a mild fibrosis group and advanced fibrosis group.ResultsHistory of appendectomy was found to be significantly more frequent in patients with advanced fibrosis than in patients with mild fibrosis (P = 0.014). Multivariate logistic analysis was conducted with age, sex, albumin, platelet count, steatosis grade, and history of appendectomy as covariates and advanced fibrosis as the dependent variable. Significant differences were identified for platelet count and history of appendectomy, identifying these as independent risk factors for advanced fibrosis in NAFLD patients. The odds ratio for appendectomy history was 39.415 (P = 0.044).ConclusionsHistory of appendectomy was significantly more frequent in NAFLD patients with advanced fibrosis, suggesting that appendectomy may represent a risk factor for advanced fibrosis in NAFLD.