Two cases of Dieulafoy's lesion in unusual sites: A rare case reports of gastrointestinal bleeding

INTRODUCTION

Dieulafoy's lesion (DL) is a vascular malformation that can lead to massive gastrointestinal bleeding. It's usually found in the stomach. However, DL's occurrence in atypical sites such as the small bowel and colon is exceptionally rare, posing significant management challenges.

CASE PRESENTATION

In this report, we present two cases of DL occurring in uncommon sites, each managed with distinct approaches. Case 1 is a 50-year-old man admitted to the emergency department due to massive GI bleeding and hemodynamic instability. The diagnosis of DL was established through computed tomography angiography and confirmed by histopathological examination after emergency surgery. Case 2 involves a 68-year-old woman presented with melena due to a colonic DL. This case was successfully managed through an endoscopic hemostasis approach.

DISCUSSION

Dieulafoy's lesions (DL) were first identified as a large submucosal artery lacking typical gastric ulcer characteristics in three of Paul Georges Dieulafoy's patients. This lesion is responsible for approximately 1-2 % of all cases of gastrointestinal bleeding. Endoscopy is the preferred method for diagnosing and managing DL lesions, especially in cases of active bleeding that is accessible. However, if endoscopic treatment or angiographic embolization fails, a surgical approach may be needed.

CONCLUSION

DL presents a diagnostic challenge due to its rarity and is not usually included in the differential diagnosis of gastrointestinal bleeding, particularly when occurring in unusual sites. Endoscopy is the preferred method to identify DL and a possible therapeutic approach in active bleeding. However, if endoscopy hemostasis fails, angiographic embolization or surgical intervention may be required.

Pure squamous cell carcinoma of the pancreas: a rare and challenging diagnosis (case report)

Squamous cell carcinoma (SCC) of the pancreas is a rare exocrine ductal tumour with unknown pathophysiology and poor treatment options. We present a case of SCC in a 59-year-old male patient who presented with epigastric pain, vomiting, anorexia, asthenia, and weight loss. Abdomino-pelvic CT revealed a pancreatic mass with adenopathy satellites. Surgical biopsies were negative, and a trans-duodenal gastric endoscopy showed suspicious lymphadenopathies and a hypoechoic lesion invading the portal vein. An anapathological study confirmed SCC at the site of intense necrotic and inflammatory changes. The patient received radio-chemotherapy, but ultimately developed peritoneal carcinoma.

Impact of the COVID-19 pandemic on digestive cancer staging, a case series

Introduction

Method

Results

Conclusion

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This is study assesses the impact of The COVID-19 pandemic on the diagnosis delay in digestive cancers and its impact on their staging.

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A three-year study that includes 165 patients, 1 year before the COVID-19 pandemic and two years during.

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The pandemic had a statistically significant impact on the staging of the tumor but no impact on the short-term outcome of the patients.

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The first study of its kind in Morocco.

Surgical and anesthetic management of paraganglioma diagnosed in a 2nd trimester parturient: Case report

Introduction

Neuroendocrine tumors represent a rare entity whose diagnosis is based on clinical, biological and radiological arguments. When they are secreting, they expose the patient to serious complications that can be much more severe during pregnancy and engage the vital prognosis of both the mother and the fetus, which requires multidisciplinary management: anesthesiologist resuscitator - obstetrician – endocrinologist.

Case presentation

In our article, we report the case of a patient with an estimated pregnancy at 25 weeks of amenorrhea (WA) with a history of 3 miscarriages related to atypical gravid hypertension.

The treatment consisted of preoperative medical preparation followed by removal of the paraganglioma and postoperative monitoring. The maternal-fetal evolution was favorable.

Conclusion

The non-negligible morbi-mortality of this type of tumors require a multidisciplinary management.

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Neuroendocrine tumors represent a rare entity whose diagnosis is based on clinical, biological and radiological arguments.

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The treatment consisted of preoperative medical preparation, removal of the paraganglioma and postoperative monitoring.

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The anesthetic and surgical management of pheochromocytomas and paragangliomas in pregnant women presents a real challenge.

Inferior mesenteric artery aneurysm revealed by massif rectal bleeding, case report

INTRODUCTION

Inferior mesenteric aneurysms are rare, usually asymptomatic. Their diagnostic is challenging based on clinical examination, ultrasonography, and abdominal CT scan; surgery remains the gold standard of treatment.

CASE REPORT

In this paper, we will report a clinical case of 62 years old man admitted to the emergency department for massif rectal bleeding due to inferior mesenteric aneurysm fistulization in the transversal colon one month after a left colectomy; the treatment was surgical consisted of a Ligation.

CONCLUSION

IMA aneurysm is a rare condition, usually asymptomatic, and it might be revealed by various symptoms, including massif rectal bleeding.

Rare association of aortoarteritis and pheochromocytoma: A case report

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Pheochromocytoma is a great masquerador.

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The coexistence of pheochromocytoma along with both aortoarteritis and renal artery stenosis is very rare.

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Management of vascular abnormalities is based on the control of catecholamine release.

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Pheochromocytoma should be included as differential diagnosis of aortoarteritis.

Introduction

Pheochromocytoma is an uncommon but treatable cause of secondary hypertension, it may present with a wide variety of manifestations. The coexistence of pheochromocytoma and vascular abnormalities is described but rarely reported entity.

Presentation of case

A 36-year-old man was admitted to our hospital for severe hypertension, examination revealed absent femoral pulses with notion of intermittent claudication. Abdominal computed tomography revealed the presence of a right adrenal pheochromocytoma. CT angiogram showed thickening of the thoracoabdominal aortic wall and the proximal portions of some of its branches with stenosis of more than 50% of the origin of the celiac trunk, bilateral occlusion of the external iliac arteries and trunk stenosis of the right renal artery. The Pheochromocytoma was surgically removed.

Discussion

Coexistence of pheyochromocytoma and vascular abnormalities especially renal artery stenosis and aortoarteritis seems to be an association rather than a coincidence.

Conclusion

To the best of our knowledge, the coexistence of pheochromocytoma along with both aortoarteritis and renal artery stenosis has not been reported thus far. The diagnosis, management and potential mechanisms underlying such an association will be discussed in this case.

Calcific pancreatitis uncovering a multiple endocrine neoplasia type 1: A case report in compliance with the scare guidelines

INTRODUCTION

Chronic pancreatitis are mostly linked to alcoholic consumption or biliary lithiasis; and Primary hyperthyroidism (PHPT) is still a very rare association and the exact physiopathology is yet to be fully unveiled to the human knowledge. We present the first case report of a calcific pancreatitis associated with not only PHPT but a multiple endocrine neoplasia (MEN) type 1.

CASE PRESENTATION

We report the case of a 52 years old woman suffering from mellitus diabetes consulting the emergency rooms for acute pancreatitis with hyperlipasemia and hypercalcemia whom final imaging discovered a pituitary gland adenoma, a left surrenal adenoma, and a parathyroid adenoma, and for the pancreas it reveiled an acute mild pancreatitis with a background of calcifications, no gallstones, no bone or renal abnormalities; and the parathyroidectomy was performed following the minimally invasive selective technique.

DISCUSSION

Calcemia levels testing routinely performed help discover hyperparathyroidism. The associations of chronic pancreatic inflammation to hyperparathyroidism needs to be studied, even if hypercalcemia is prooven to be a risk factor of pancreatitis; the mechanism behind this association is brievely described. parathyroidectomy is the definitive cure for hyperparathyroidism, the technique advances has shown effective localization of the responsible adenoma and the intraoperative testing of parathormon levels after resection decreasing is a very reliable extemporaneous sign for the success of the procedure.

CONCLUSION

The endocrine system is synchronized; meaning the injury of one gland should start the search for others. In our case, the first main lead should not have been the acute pancreatitis but her diabetes. In the future we suggest that diabetes primary explorations may need a pancreatic imaging and endocrine explorations even though it could get pricier for the healthcare system, but giving the complications that we could prevent; it is to be considered.

Acute hemoperitoneum after ruptured hepatocellular carcinoma: First Moroccan SCARE-compliant case report and literature review

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Acute hemoperitoneum after a spontaneously ruptured hepatocellular carcinoma (HCC) is a rare complication.

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In cases with stable conditions, imaging guided by computed tomography (CT) enables arterial embolisation.

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Surgery is a choice after failure of embolisation or in case of severe hemodynamic instability.

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The prognostic outcomes of ruptured HCC depend mostly on the underlying liver function.

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Successful management by one-stage surgery allowed radical treatment of this rare entity.

Introduction

Acute hemoperitoneum with a spontaneously ruptured hepatocellular carcinoma (HCC) is a rare type of internal bleeding that requires a multidisciplinary management approach.

Presentation of case

In this case report, we describe a fortuitously ruptured peripheral and discovered HCC in an 81-years-old woman treated effectively using hepatectomy.

Discussion

The use of the computed tomography (CT) angiography to diagnose the stability of the patient’s condition allows both arterial embolization in case of active bleeding and the evaluation of the underlying hepatopathy. The place of surgery is particularly upon after both the failure of arterial embolization and while facing a severe hemodynamic instability. The surgical strategy varies between perihepatic tamponnade and a surgical resection in one or more stages. The prognosis of a ruptured HCC depends mainly on the underlying liver’s function.

Conclusion

Multidisciplinary management of spontaneously ruptured HCC results in the same survival outcome as non-ruptured HCC at the same stage of hepatopathy.

P903 Myocardial work in moderate to severe aortic versus primary mitral regurgitation

Funding Acknowledgements

None

OnBehalf

None

BACKGROUND

Myocardial work is an emerging non-invasive technic based on echocardiographic pressure-strain loops that assess left ventricular (LV) function. The method was studied in a large variety of pathologies, but its role in the assessment of valvular regurgitations is still unknown.

PURPOSE

To compare myocardial work indices in moderate and severe aortic and primary mitral regurgitation.

METHODS

Seventy-eight patients with moderate and severe aortic regurgitation (AR) or primary mitral regurgitation (MR) and preserved LV ejection fraction (LVEF > 50%) were retrospectively analyzed.. Patients with significant valvular stenosis were excluded. Demographic, clinical and echocardiographic data, including LV global longitudinal strain (GLS) and myocardial work indices, were assessed.

RESULTS

The mean age was 58 ± 14 years, and 46 patients (59%) were men. Thirty seven patients had moderate or severe AR and 41 patients had moderate or severe MR. The two groups were homogeneous in terms of demographic and clinical data, except for age. As expected, diastolic blood pressure was lower in patients with AR compared to MR group (67 ± 8 mmHg vs. 73 ± 10 mmHg, p = 0,003), patients with MR had a higher LVEF compared to AR group (63 ± 6% vs 59 ± 6%, p = 0,03), and a higher left atrial indexed volume (53 ± 16ml/m² vs 34 ± 12ml/m², p < 0.0001). Overall, GLS, myocardial work index (GWI) and myocardial constructive work (GCW) were significantly lower in patients with moderate or severe AR compared to MR ( -18,1 ±3% vs -21,3 ±3,3%, p < 0,0001; 1849 ± 393 vs 2285 ± 499, p < 0,0001; and 2194 ± 395 vs 2576 ± 594, p = 0,003, respectively). Global wasted work (GWW) and global work efficiency (GWE) were similar. When comparing only asymptomatic patients, results were similar, with higher GLS, GWI and GCW in moderate to severe MR vs. AR (-22,9 ± 3,4 vs.-18,4 ± 3,4%, p <0,001; 2446 ± 570 vs. 1927 ± 338, p = 0.001 and 2767 ± 688 vs. 2236 ± 377, p = 0.005). Interestingly, when comparing asymptomatic patients with a LVEF > 50% for AR, and LVEF > 60% for MR, GWI and GCW were significantly lower in MR group, despite higher GLS values (1852 ± 398 vs. 2322 ± 527, p < 0.001; 2194 ± 400 vs. 2615 ± 638, p = 0.005; -22,1 ± 3,3% vs. -18,2 ± 2,9, p < 0.001).

CONCLUSION

Patients with moderate to severe MR have higher values of GLS, global work index and global constructive myocardial work. This could translate into the fact that in moderate or severe MR, the myocardium develops a higher amount of work than in AR, maybe to account for the loss of stroke volume into the left atrium. In asymptomatic moderate to severe MR with LVEF > 60%, LV myocardium develops less work than in moderate to severe AR with a LVEF > 50%, suggesting maybe a compensated state.

P5981Impact of radiotherapy on myocardial function and paravalvular leaks after transcatheter aortic valve implantation (TAVI)

Introduction

Thanks to the anticancer therapies, the life expectancy of the oncologic patients has noticeably increased, but several cardiac diseases can be observed in these patients as the result of the cardiotoxic effects.

Purpose

To investigate the impact of radiotherapy on the clinical and echocardiographic outcomes, in patients with severe aortic stenosis (AS) and preserved left ventricle ejection fraction (LVEF) treated with transcatheter aortic valve implantation (TAVI).

Methods

We recruited patients with severe AS and left ventricular ejection fraction (LVEF) ≥50‰ treated with TAVI and who received prior radiotheraphy. Patients with LVEF <50‰, treated with valve in valve, with inadequate acoustic windows or the absence of echocardiographic images pre-TAVI and after 3–6 months were excluded. Demographic, clinical and echocardiographic data were recorded.

Results

102 patients were included in the present analysis. They were divided in two groups: 19 (18‰) with an oncologic history treated with previous left thoracic/mediastinal radiotherapy and 83 (82‰) patients without an oncologic history. The two groups were homogeneous in terms of demographic and clinical data, brain natriuretic peptide (BNP), echocardiographic data pre-TAVI. They only differed for a greater prevalence of mitral stenosis and calcifications in the oncologic patients versus the non-oncologics (respectively 36‰ vs. 12‰ p=0,016; 73‰ vs. 29‰ p=0,001). No differences in terms of in-hospital clinical outcomes were observed. The echocardiographic evaluation in both groups showed a significant decrease of the peak velocities and of the transprosthetic gradients. There was a higher incidence of at least moderate degree paraprosthetic leaks in the oncologic group vs. the non-oncologic one: 6 (31‰ total leaks, 37‰ leaks >2+) vs. 7 (8‰ total leaks, 12‰ leaks >2+); p=0.029. After 3–6 months, there was not a statistically significant improvement of ejection fraction (EF) in neither of the two groups but there was a statistically significant improvement of transmural, subepicardial and subendocardial longitudinal strain values in the non-oncologic group compared to pre-TAVI values, respectively −19±4 vs. −17±4 (p<0.001); −17±3 vs. −15±3 (p<0.001); −22±4 vs. −19.8±4 (p<0.001). Any statistically significant improvement was detected in the group with history of anticancer treatments between the longitudinal strain values post and pre-TAVI (−18±3‰ vs. −16±3‰; −14±3‰ vs. −20±5‰; −20 ±± 5‰ vs. −19±4‰).

Conclusions

Patients affected by severe AS treated with TAVI and who received received prior radiotheraphy, showed the absence of statistically significant improvement of multilayer strain values, at 3–6 months after TAVI. Oncologic patients also had a higher incidence of haemodynamically relevant paravalvular leaks after the intervention, compared to the non-oncologic patients.

[A quadricuspid aortic valve passed unnoticed]

The quadricuspid aortic valve is a rare congenital anomaly that could be silent for a long time. It is mostly isolated but it may also be associated with other malformations, especially anomalies of the coronary artery insertion. It can lead to aortic regurgitation with several degrees of severity, and it should be diagnosed as soon as possible to avoid left ventricular dysfunction and its morbi-mortality. We report the case of a 67-years-old female patient with recent discovery of moderate aortic regurgitation, which has beneficiated from surgical closure of an atrial septal defect in her childhood, and who has never been diagnosed with a quadricuspid aortic valve.

[Clinical case of the month. Peritonitis after spontaneous rupture of pyonephrosis. A case report]

Peritonitis after spontaneous rupture of pyonephrosis is a rare complication, usually diagnosed intraoperatively. We report the case of a 35 year old woman who was admited for an acute abdomen. Ultrasound showed features of acute peritonitis, with left pyonephrosis, confirmed by a CT-SCAN. Treatment consisted of laparotomy with nephrectomy and abdominal washing and draining. The outcome was favourable.

Body fluid osmolality and tonicity in preterm infants

In adult patients, a recent physiological approach for the osmoregulatory system based on body fluid tonicity (the so-called effective osmolality) seems to provide better information on water movements than does the classical body fluid osmolality. To evaluate whether plasma or urinary tonicities could give a better assessment of osmoregulation than plasma and urine osmolalities in sick preterm infants cared for in a NICU. A prospective study was conducted in 30 preterm infants (BW=1284+/-377 g; GA=28.8+/-1.7 weeks). Fifteen consecutive 8-h urine collections were performed for each infant from the 8th h of life (450 periods). A plasma sample was obtained at the end of each urine collection. Sodium, potassium, creatinine, osmolality and tonicity were measured or calculated in urine and blood samples as often as possible. Hypernatremia (PNa=146-149 mmol/l) was observed in seven infants (23.3%) and in 5.9% of the periods. Fifty-three percent of the infants and 20.4% of the periods presented with plasma hyperosmolality (>300 mosmol/kg H2O). The relationship between Posm and PNa was significant, but the clinical relevance was weak (r(2)=0.411; P<0.001). Plasma osmolality (Posm) positively correlated with urine osmolality (Uosm), but did not correlate significantly with CH2O/100 ml GFR. Plasma tonicity (2x(PNa+PK)) positively correlated with both urine tonicity (2x(UNa+UK)) and effective water clearance (EWC/100 ml GFR). On an individual basis, the linear relationship between urine and plasma osmolalities was significantly weaker than the relationship between urine and plasma tonicities. This study suggests that the calculation of plasma and urine tonicities allows a better assessment of water movements in body fluid compartments than plasma and urine osmolalities.

Role of Fas and granule exocytosis pathways in tumor-infiltrating T lymphocyte-induced apoptosis of autologous human lung-carcinoma cells

We have isolated a cytotoxic T lymphocyte (CTL) clone, Heu161, that reacts specifically with the human autologous lung carcinoma cell line IGR-Heu. We first demonstrated that IGR-Heu lacked Fas-receptor expression and was resistant to CD95-induced apoptosis. To further elucidate the role of Fas in tumor immune surveillance, we have stably transfected IGR-Heu with a Fas-expression vector and isolated CD95-sensitive and -resistant clones. Our data indicated that the resistance of 2 selected Fas-transfected clones to CD95-mediated lysis correlated with down-regulation of caspase-8 or its lack of cleavage and subsequent activation. All Fas transfectants, either sensitive or resistant to anti-Fas agonistic antibody, were as efficiently lysed by the CTL clone as the parental cell line. In addition, neither anti-Fas-blocking antibody nor Fas-Fc molecule inhibited T-cell lysis of Fas-sensitive tumor clone. This cytotoxicity was extracellular Ca(2+)-dependent and abolished in the presence of EGTA, indicating that it was mainly granzyme-mediated. Interestingly, although the caspase inhibitor z-VAD-fmk had no effect on tumor-cell lysis, it efficiently blocked target DNA damage triggered by autologous CTLs via the granule exocytosis pathway, indicating that the latter event was caspase-dependent. The present results suggest that lung carcinoma-specific CTLs use mainly a granule exocytosis-dependent pathway to lyse autologous target cells and that these effectors are able to circumvent alteration of the Fas-triggered intracellular signalling pathway via activation of a caspase-independent cytoplasmic death mechanism.

Role of Fas and granule exocytosis pathways in tumor-infiltrating T lymphocyte-induced apoptosis of autologous human lung-carcinoma cells

We have isolated a cytotoxic T lymphocyte (CTL) clone, Heu161, that reacts specifically with the human autologous lung carcinoma cell line IGR-Heu. We first demonstrated that IGR-Heu lacked Fas-receptor expression and was resistant to CD95-induced apoptosis. To further elucidate the role of Fas in tumor immune surveillance, we have stably transfected IGR-Heu with a Fas-expression vector and isolated CD95-sensitive and -resistant clones. Our data indicated that the resistance of 2 selected Fas-transfected clones to CD95-mediated lysis correlated with down-regulation of caspase-8 or its lack of cleavage and subsequent activation. All Fas transfectants, either sensitive or resistant to anti-Fas agonistic antibody, were as efficiently lysed by the CTL clone as the parental cell line. In addition, neither anti-Fas-blocking antibody nor Fas-Fc molecule inhibited T-cell lysis of Fas-sensitive tumor clone. This cytotoxicity was extracellular Ca(2+)-dependent and abolished in the presence of EGTA, indicating that it was mainly granzyme-mediated. Interestingly, although the caspase inhibitor z-VAD-fmk had no effect on tumor-cell lysis, it efficiently blocked target DNA damage triggered by autologous CTLs via the granule exocytosis pathway, indicating that the latter event was caspase-dependent. The present results suggest that lung carcinoma-specific CTLs use mainly a granule exocytosis-dependent pathway to lyse autologous target cells and that these effectors are able to circumvent alteration of the Fas-triggered intracellular signalling pathway via activation of a caspase-independent cytoplasmic death mechanism.

3-Methyladenine-DNA glycosylase (MPG protein) interacts with human RAD23 proteins

Human 3-methyladenine-DNA glycosylase (MPG protein) initiates base excision repair by severing the glycosylic bond of numerous damaged bases. In comparison, homologues of the Rad23 proteins (hHR23) and the hXPC protein are involved in the recognition of damaged bases in global genome repair, a subset of nucleotide excision repair. In this report, we show that the hHR23A and -B also interact with the MPG protein and can serve as accessory proteins for DNA damage recognition in base excision repair. Furthermore, the MPG.hHR23 protein complex elevates the rate of MPG protein-catalyzed excision from hypoxanthine-containing substrates. This increased excision rate is correlated with a greater binding affinity of the MPG protein-hHR23 protein complex for damaged DNA. These data suggest that the hHR23 proteins function as universal DNA damage recognition accessory proteins in both of these major excision repair pathways.

Promoter structure and cell cycle dependent expression of the human methylpurine-DNA glycosylase gene

The methylpurine-DNA glycosylase (MPG) gene coding for human 3-methyladenine (3-meAde)-DNA glycosylase functions in the first step of base excision repair (BER) to remove numerous damaged bases including 3-meGua, ethenoadenine, and hypoxanthine (Hx) in addition to 3-meAde. In this report, we identify the length of the minimal MPG promoter region, demonstrate the involvement of several transcription factors in expression of the MPG gene, and determine the point at which transcription initiates. We also demonstrate that control of MPG expression is linked to MPG activity. To initiate studies on how the MPG functions with the ensemble of BER genes to effect repair, we have investigated the cell cycle control of MPG and other BER genes in normal human cells. Steady-state mRNA levels of MPG, human Nth homologue (NTH), and uracil-DNA glycosylase (UDG), DNA glycosylases, and human AP site-specific endonuclease (APE), an endonuclease incising DNA at abasic sites, are cell cycle dependent. In contrast, expression levels of genes coding for human 8-oxoguanine-DNA glycosylase (OGG1) and TDG DNA glycosylases, and omicron 6-methylguanine-DNA methyltransferase (MGMT) gene, and the RPA4 subunit gene do not vary with cell cycle. These observed cell cycle dependent differences might reflect distinct roles of individual BER proteins in mutation avoidance.

Interaction of the recombinant human methylpurine-DNA glycosylase (MPG protein) with oligodeoxyribonucleotides containing either hypoxanthine or abasic sites

Methylpurine-DNA glycosylases (MPG proteins, 3-methyladenine-DNA glycosylases) excise numerous damaged bases from DNA during the first step of base excision repair. The damaged bases removed by these proteins include those induced by both alkylating agents and/or oxidizing agents. The intrinsic kinetic parameters (k(cat) and K(m)) for the excision of hypoxanthine by the recombinant human MPG protein from a 39 bp oligodeoxyribonucleotide harboring a unique hypoxanthine were determined. Comparison with other reactions catalyzed by the human MPG protein suggests that the differences in specificity are primarily in product release and not binding. Analysis of MPG protein binding to the 39 bp oligodeoxyribonucleotide revealed that the apparent dissociation constant is of the same order of magnitude as the K(m) and that a 1:1 complex is formed. The MPG protein also forms a strong complex with the product of excision, an abasic site, as well as with a reduced abasic site. DNase I footprinting experiments with the MPG protein on an oligodeoxyribonucleotide with a unique hypoxanthine at a defined position indicate that the protein protects 11 bases on the strand with the hypoxanthine and 12 bases on the complementary strand. Competition experiments with different length, double-stranded, hypoxanthine-containing oligodeoxyribonucleotides show that the footprinted region is relatively small. Despite the small footprint, however, oligodeoxyribonucleotides comprising <15 bp with a hypoxanthine have a 10-fold reduced binding capacity compared with hypoxanthine-containing oligodeoxyribonucleotides >20 bp in length. These results provide a basis for other structural studies of the MPG protein with its targets.

Repair of DNA alkylation damage

Alkylation damage of DNA is one of the major types of insults which cells must repair to remain viable. One way alkylation damaged ring nitrogens are repaired is via the Base Excision Repair (BER) pathway. Examination of mutants in both BER and Nucleotide Excision Repair show that there is actually an overlap of repair by these two pathways for the removal of cytotoxic lesions in Escherichia coli. The enzymes removing damaged bases in the first step in the BER pathway are DNA glycosylases. The coding sequences for a number of methylpurine-DNA glycosylases (MPG proteins) were cloned, and a comparison of the amino-acid sequences shows that there are some similarities between these proteins, but nonetheless, compared to other DNA glycosylases, MPG proteins are more divergent. MPG proteins have been purified to homogeneity and used to identify their substrates ranging from methylating agents to deamination products to oxidatively damaged bases. The ligation-mediated polymerase chain reaction has been used to study the formation of alkylation damage, and its repair in mammalian cells. We have studied DNA damage in the PGK1 gene for a series of DNA alkylating agents including N-methyl-N'-nitro-N-nitrosoguanidine, Mechlorethamine, and Chlorambucil and shown that the damage observed in the PGK1 (phosphoglycerate kinase 1) gene depends on the alkylating agent used. This report reviews the literature on the MPG proteins, DNA glycosylases removing 3-methyladenine, and the use of these enzymes to detect DNA damage at the nucleotide level.

Repair of DNA alkylation damage

Alkylation damage of DNA is one of the major types of insults which cells must repair to remain viable. One way alkylation damaged ring nitrogens are repaired is via the Base Excision Repair (BER) pathway. Examination of mutants in both BER and Nucleotide Excision Repair show that there is actually an overlap of repair by these two pathways for the removal of cytotoxic lesions in Escherichia coli. The enzymes removing damaged bases in the first step in the BER pathway are DNA glycosylases. The coding sequences for a number of methylpurine-DNA glycosylases (MPG proteins) were cloned, and a comparison of the amino-acid sequences shows that there are some similarities between these proteins, but nonetheless, compared to other DNA glycosylases, MPG proteins are more divergent. MPG proteins have been purified to homogeneity and used to identify their substrates ranging from methylating agents to deamination products to oxidatively damaged bases. The ligation-mediated polymerase chain reaction has been used to study the formation of alkylation damage, and its repair in mammalian cells. We have studied DNA damage in the PGK1 gene for a series of DNA alkylating agents including N-methyl-N'-nitro-N-nitrosoguanidine, Mechlorethamine, and Chlorambucil and shown that the damage observed in the PGK1 (phosphoglycerate kinase 1) gene depends on the alkylating agent used. This report reviews the literature on the MPG proteins, DNA glycosylases removing 3-methyladenine, and the use of these enzymes to detect DNA damage at the nucleotide level.

Hepatic storage and transport of n-3 and n-6 polyunsaturated fatty acids by very-low-density lipoproteins in growing rats fed low- or adequate-protein diets with sunflower, soybean, coconut, and salmon oils

Protein and essential fatty acid (EFA) deficiencies may both occur in chronic malnutrition and have common symptoms. To determine the interactions between dietary protein intake and EFA availability, rats were fed purified diets containing 20% or 2% casein and 5% as one of four fats (sunflower, soybean, coconut, or salmon oil) that differed particularly in their n-6 and n-3 polyunsaturated fatty acids (PUFAs). Protein malnutrition enhanced hepatic triacylglycerol and cholesterol concentrations while decreasing hepatic protein and phospholipid contents and mass and components of very-low-density lipoprotein (VLDL). The ratio of PUFAs to saturated fatty acids (SFAs) was consistently depressed by protein malnutrition in liver and VLDL triacylglycerol and phospholipid. Total n-6 and n-3 fatty acids were diminished by protein malnutrition, except with salmon oil, with which a decrease in 20:5n-3 was compensated for by an increase in 22:6n-3. The ratio of 20:4n-6 to 18:2n-6 was enhanced in liver phospholipid and VLDL triacylglycerol, and modified little in liver triacylglycerol. Generally, the ratio of 20:3n-9 to 20:4n-6, an index for EFA deficiency, was raised with protein malnutrition in liver triacylglycerol and phospholipid and in VLDL triacylglycerol. The extent of changes in each fatty acid proportion varied according to the oil fed. Overall, VLDL-apolipoprotein concentrations were, in general, strongly reduced with protein malnutrition. In conclusion, protein malnutrition may accelerate marginal EFA deficiency and decrease long-chain PUFA bioavailability and thus increase EFA requirement.

A synthetic peptide from the human immunodeficiency virus type-1 integrase exhibits coiled-coil properties and interferes with the in vitro integration activity of the enzyme. Correlated biochemical and spectroscopic results

Integration of the human immunodeficiency virus (HIV-1) DNA into the host genome is catalysed by a virus-encoded protein integrase. Here, we report some of the structural and functional properties of two synthetic peptides: integrase-(147-175)-peptide reproducing the residues 147-175 (SQGVVESMNKELK159KIIGQVRDQAEHLKTAY) of the HIV-1 integrase, and [Pro159] integrase-(147-175)-peptide where the lysine 159 is substituted for a proline. Circular dichroism revealed that both peptides are mostly under unordered conformation in aqueous solution, contrasting with the alpha-helix exhibited by residues 147-175 in the protein crystal structure. In a weak alpha-helix-promoting environment, integrase-(147-175)-peptide self-associated into stable coiled-coil oligomers, while [Pro159] integrase-(147-175)-peptide did not. This property was further confirmed by cross-linking experiments. In our in vitro experiments, only integrase-(147-175)-peptide was able to reduce the integration activity of the enzyme. We propose that the inhibitory activity shown by integrase-(147-175)-peptide is dependent on its ability to bind to its counterpart in integrase through a peptide-protein coiled-coil structure disturbing the catalytic properties of the enzyme.

Binding of Net-Fla, a netropsin-flavin hybrid molecule, to DNA: molecular mechanics and dynamics studies in vacuo and in water solution

We have studied the binding of the hybrid netropsin-flavin (Net-Fla) molecule onto four sequences containing four A. T base pairs. Molecular mechanics minimizations in vacuo show numerous minimal conformations separated by one base pair. 400 ps molecular dynamics simulations in vacuo have been performed using the lowest minima as the starting conformations. During these simulations, the flavin moiety of the drug makes two hydrogen bonds with an amino group of a neighboring guanine. A 200 ps molecular dynamics simulation in explicit water solution suggests that the binding of Net-Fla upon the DNA substrate is enhanced by water bridges. A water molecule bridging the amidinium of Net-Fla to the N3 atom of an adenine seems to be stuck in the drug-DNA complex during the whole simulation. The fluctuations of the DNA helical parameters and of the torsion angles of the sugar-phosphate backbone are very similar in the simulations in vacuo and in water. The time auto-correlation functions for the DNA helical parameters decrease rapidly in the picosecond range in vacuo. The same functions computed from the water solution molecular dynamics simulations seem to have two modes: the rapid mode is similar to the behavior in vacuo, and is followed by a slower mode in the 10 ps range.

Alternate strand DNA triple helix-mediated inhibition of HIV-1 U5 long terminal repeat integration in vitro

Integration of the human immunodeficiency virus (HIV) DNA into the host genome is an obligatory process in the replicative life cycle of the virus. This event is mediated in vitro by integrase, a viral protein which binds to specific sequences located on both extremities of the DNA long terminal repeats (LTRs). These sites are highly conserved in all HIV genomes and thus provide potential targets for the selective inhibition of integration. The integrase-binding site located on the HIV-1 U5 LTR end contains two adjacent purine tracts on opposite strands, 5' . . . GGAAAATCTCT-3'/3'-CCTTTTAGAGA . . . 5', in parallel orientations. A single strand oligonucleotide 5'-GGTTTTTGTGT-3' was designed to associate with these tracts via its ability to form a continuous alternate strand DNA triplex. Under neutral pH and physiological temperature, the oligonucleotide, tagged with an intercalator chromophore oxazolopyridocarbazole, formed a stable triplex with the target DNA. The occurrence of this unusual triplex was demonstrated by both DNase I footprinting and electron microscopy. The triplex inhibits the two steps of the integrase-mediated reactions, namely, the endonucleolytic cleavage of the dinucleotide 5'-GT-3' from the 3' end of the integration substrate and the integration of the substrate into the heterologous target DNA. The midpoints for both inhibition reactions were observed at oligonucleotide concentrations of 50-100 nM. We believe that these results open new possibilities for the specific targeting of viral DNA LTR ends with the view of inhibiting integration under physiological conditions.

A molecular mechanics and dynamics study of alternate triple-helices involving the integrase-binding site of the HIV-1 virus and oligonucleotides having a 3'-3' internucleotide junction

Triple helix formation by oligonucleotides can be extended beyond polypurine tracts with the help of specially designed linkers. In this paper we focus our attention on the integrase-binding site of the HIV-1 virus located on the U5 LTR end which contains two adjacent purine tracts on opposite strands. Two alternate triple helices with a 3'-3' junction in the third strand are considered: 5'-GGTTTTp3'-3'pTGTGT-5' and 5'-GGAAAAp3'-3'pAGAGA-5' The structural plausibility of these triplexes is investigated using molecular mechanics and dynamics simulations, both in vacuo and in aqua. The non-isomorphism of the triplets in the GpT steps in the first sequence, gives rise to non canonical conformations in the torsion angles, hydration appears to be crucial for this triplex. Sugar puckers are predominantly South during in vacuo simulations while they turn East in aqua. In the simulation in aqua the triplexes are shrouded by an hydration shell, however, we have not been able to detect any permanent hydrogen bond bridge between DNA and water. The solvation of ions as well as their radial distribution, appear to be relatively well behaved despite the artifacts known to be generated by the simulation procedure. The experimental feasibility of these structures is discussed.

Sequence-directed single strand cleavage of DNA by a netropsin-flavin hybrid molecule

In an attempt to obtain sequence specific DNA-cleaving molecules, we have synthesized a series of hybrid minor groove binders composed of a photoactiveable isoalloxazine (flavin) chromophore linked through a polymethylenic chain to a bis-pyrrolecarboxamide moiety related to netropsin. Like netropsin, the hybrid derivatives preferentially bind to A+T-rich sequences. Activation of the flavin chromophore by visible light results in the appearance of single strand breaks in the vicinity of the DNA binding site. We have further investigated the cleavage affinity properties of one of these compounds referred to as netropsin-flavin (Net-Fla) and considered as representative of the series. Net-Fla cleaves only one strand at a specific locus downstream of 5'-AAAT-3', upstream of 5'-TAAA-3' and on either side of a 5'-AAAA-3' sequence. Net-Fla cleaves both strands downstream to 5'-AATT-3'. This makes the properties of Net-Fla similar to that of a restriction endonuclease and provides additional insight into establishing the rules for the readout of B-DNA helix by non-nucleotidic compounds. Using molecular modeling, we show that Net-Fla binds to an asymmetric site in one orientation. The values of the energetic minima lie in the same order as expected from the cleavage patterns, which suggests that the oriented cleavage is a consequence of a sequence-oriented binding of Net-Fla in the DNA minor groove.

Dietary protein deficiency affects n-3 and n-6 polyunsaturated fatty acids hepatic storage and very low density lipoprotein transport in rats on different diets

Fatty livers and the similarity between the skin lesions in kwashiorkor and those described in experimental essential fatty acid (EFA) deficiency have led to the hypothesis that protein and EFA deficiencies may both occur in chronic malnutrition. The relationship between serum very low density lipoprotein (VLDL) and hepatic lipid composition was studied after 28 d of protein depletion to determine the interactions between dietary protein levels and EFA availability. Rats were fed purified diets containing 20 or 2% casein and 5% fat as either soybean oil rich in EFA, or salmon oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, or hydrogenated coconut oil poor in EFA. Animals were divided into six groups, SOC (20% casein + 5% soybean oil), SOd (2% casein + 5% soybean oil), COC (20% casein + 5% hydrogenated coconut oil), COd (2% casein + 5% hydrogenated coconut oil), SAC (20% casein + 5% salmon oil) and SAd (2% casein + 5% salmon oil). After 28 d, liver steatosis and reduced VLDL-phospholipid contents (P < 0.001) were observed in protein-deficient rats. In protein deficiency, triacylglycerol and phospholipid fatty acid compositions in both liver and VLDL showed a decreased polyunsaturated-to-saturated fatty acid ratio. This ratio was higher with the salmon oil diets and lower with the hydrogenated coconut oil diets. Furthermore, independent of the oil in the diet, protein deficiency decreased linoleic and arachidonic acids in VLDL phospholipids. Conversely, despite decreased proportions of EPA at low protein levels, DHA levels remained higher in rats fed salmon oil diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in fatty acid compositions of total serum and lipoprotein particles, in growing rats given protein-deficient diets with either hydrogenated coconut or salmon oils as fat sources

The present study examines the effects of dietary saturated (hydrogenated coconut oil) and polyunsaturated (salmon oil) fats on the composition and metabolism of lipoproteins in growing rats fed on protein-deficient diets. Four groups of rats were fed on the following diets for 28 d: 200 g casein + 50 g coconut oil (COC)/kg, 20 g casein + 50 g coconut oil (COd)/kg, 200 g casein + 50 g salmon oil (SAC)/kg, 20 g casein + 50 g salmon oil (SAd)/kg. Both protein-deficient groups exhibited low concentrations of protein and triacylglycerol (in serum, very-low-density lipoprotein (VLDL), low-density lipoprotein-high-density lipoprotein, (LDL-HDL1) and HDL2-3), of cholesterol (in LDL-HDL1) and of phospholipids (in VLDL). Furthermore, serum and VLDL cholesterol concentrations were also reduced in the SAd group. Compared with rats given 200 g casein/kg diets, those fed on low-protein diets presented lower linoleic and arachidonic acid levels, in serum phospholipids and a dramatic decrease in the polyunsaturated: saturated fatty acid value. Relative amounts of linoleic and arachidonic acids in phospholipids of VLDL and HDL2-3 were also lowered in the COd group but not in the SAd group. However, proportions of 22:5n-6 and 22:6n-3 in VLDL and HDL2-3 phospholipid fractions were enhanced in the COd and SAd groups respectively. The most affected apolipoproteins (apo) were apo B100 and apo B48 in rats fed on protein-deficient diets, apo AI and apo E in the COd group, and apo AIV in the SAd group. Compared with rats fed hydrogenated coconut oil diets, those fed salmon oil diets had enhanced LDL-HDL1 and HDL2-3 but lower VLDL total apolipoproteins (mainly due to a fall in apo B100 and apo B48). Arachidonic and eicosapentaenoic acids, which are impaired by protein deficiency, are the precursors of prostaglandins, thromboxanes and leukotrienes which are implicated in a number of regulatory processes. Our results demonstrate that protein malnutrition is associated with impaired metabolism of arachidonic and eicosapentaenoic acids. Protein malnutrition and essential fatty acid (EFA) deficiency are characterized by many common clinical features and the link between the two may be an impaired production of eicosanoids, since arachidonic and eicosapentaenoic acids are the precursors of these important metabolic regulators. Because of the apparent involvement of EFA deficiency in the aetiology of protein malnutrition, it may be prudent to include adequate amounts of EFA in diets of infants suffering from kwashiorkor.

Changes in serum and lipoprotein fatty acids of growing rats fed protein-deficient diets with low or adequate linolenic acid concentrations

The effects of a protein-deficient diet associated with sunflower oil [adequate in 18:2(n-6), poor in 18:3(n-3)] or soybean oil [adequate in both 18:2(n-6) and 18:3(n-3)] on lipid serum and lipoprotein compositions were studied in growing rats. Four groups of rats were fed different diets: SFC (20% casein + 5% sunflower oil); SFd (2% casein + 5% sunflower oil); SC (20% casein + 5% soybean oil); Sd (2% casein + 5% soybean oil). After 28 d, both protein-deficient groups exhibited low concentrations of protein, phospholipid, triacylglycerol and total cholesterol in serum and VLDL. Compared with rats fed 20% casein diets, those fed low protein diets had lower 18:2(n-6) and 20:4(n-6) in phospholipids of serum, VLDL and HDL2-3, and the 20:4(n-6)/18:2(n-6) ratio was twofold higher in triacylglycerols of serum and VLDL. In the SFd-fed group, 22:5(n-6) was higher than in the SFC-fed group for both triacylglycerols and phospholipids in overall lipoprotein fractions studied. In addition, the 20:3(n-9)/20:4(n-6) ratio was 0.1 in HDL2-3 phospholipids of the SFd-fed group. Sunflower oil-fed rats compared with soybean oil-fed rats had greater monounsaturated fatty acids and lower total (n-3) fatty acids in both triacylglycerols and phospholipids of serum, VLDL and HDL2-3, as well as lower total (n-6) fatty acids in serum and VLDL triacylglycerols. Apolipoproteins (apo) of VLDL were drastically depressed in rats fed protein-deficient diets, whereas apo-AI of HDL2-3 showed a particular resistance. Likewise, sunflower oil-fed rats had enhanced apo-B48 of VLDL and apo-C, apo-AII and apo-AIV of HDL2-3. The present findings show that some effects of protein malnutrition were enhanced by alpha-linolenic acid deficiency, in particular reduced (n-6) and (n-3) fatty acid bioavailability.