Shear Stress Induces Differentiation of Endothelial Lineage Cells to Protect Neonatal Brain from Hypoxic-Ischemic Injury through NRP1 and VEGFR2 Signaling.

Neonatal hypoxic-ischemic (HI) brain injuries disrupt the integrity of neurovascular structure and lead to lifelong neurological deficit. The devastating damage can be ameliorated by preserving the endothelial network, but the source for therapeutic cells is limited. We aim to evaluate the beneficial effect of mechanical shear stress in the differentiation of endothelial lineage cells (ELCs) from adipose-derived stem cells (ASCs) and the possible intracellular signals to protect HI injury using cell-based therapy in the neonatal rats. The ASCs expressed early endothelial markers after biochemical stimulation of endothelial growth medium. The ELCs with full endothelial characteristics were accomplished after a subsequential shear stress application for 24 hours. When comparing the therapeutic potential of ASCs and ELCs, the ELCs treatment significantly reduced the infarction area and preserved neurovascular architecture in HI injured brain. The transplanted ELCs can migrate and engraft into the brain tissue, especially in vessels, where they promoted the angiogenesis. The activation of Akt by neuropilin 1 (NRP1) and vascular endothelial growth factor receptor 2 (VEGFR2) was important for ELC migration and following in vivo therapeutic outcomes. Therefore, the current study demonstrated importance of mechanical factor in stem cell differentiation and showed promising protection of brain from HI injury using ELCs treatment.

Mice deficient in neuropeptide PACAP demonstrate increased sensitivity to in vitro kidney hypoxia.

One of the well-known effects of pituitary adenylate cyclase activating polypeptide (PACAP) is its neuroprotective and cytoprotective actions including renoprotective effects. Mice deficient in endogenous PACAP exhibit several behavioral, metabolic, and developmental alterations. Furthermore, PACAP-deficient mice have larger infarct volume in a model of cerebral ischemia, delayed axonal regeneration, and increased cell death in cerebellar oxidative stress. We have previously demonstrated that PACAP-deficient mice have increased susceptibility to in vitro oxidative stress, which can be counteracted by exogenous PACAP treatment. These results demonstrate that endogenous PACAP has a protective role against various stressors. The objective of the present study was to investigate whether endogenous PACAP has a protective effect in the kidney against in vitro hypoxia. Kidney cell cultures were isolated from wild-type and PACAP-deficient mice, and cell viability was assessed after in vitro hypoxia induced using CoCl(2). The sensitivity of cells from PACAP-deficient mice was increased to hypoxia: both after 24 and 48 hours of exposure, cell viability was significantly reduced compared with that in control wild-type mice. These results show that endogenous PACAP protects against noxious stimuli in the kidney and that PACAP may act as a stress sensor in renal cells.

Mesenteric venous thrombosis with bowel infarction and hyperhomocysteinemia due to homozygous methylenetetrahydrofolate reductase C677T genotype.

The case of a 30-year-old man with bowel infarction due to mesenteric venous thrombosis and multiple risk factors, including mild hyperhomocysteinemia due to methylenetetrahydrofolate reductase C677T polymorphism and recent abdominal surgery, is reported. His clinical manifestation consisted of persistent abdominal pain; complementary examinations showed nonspecific findings such as leukocytosis and dilated loops of the bowel. The diagnosis of mesenteric venous thrombosis with bowel infarction was made during laparotomy and confirmed by anatomopathologic examination. He underwent segmental resection associated with lifelong anticoagulant therapy and vitamin B supplementation with a favorable course.

[Scintigraphic findings in a patient with sickle-cell thalassemia and recurrent pain attacks]. / Szintigraphische Befunde bei einem Patienten mit Sichelzell-Thalassämie und rezidivierenden Schmerzattacken.

The case of an eight years old African boy who suffers from sickle cell-thalassemia is presented. In the course of the disease frequent pain attacks occurred within the abdomen and extremities, recently also within the trunk. Local pain, at some occasions in combination with local swelling and always positive laboratory parameters for inflammation, hindered a solely clinical differentiation between bone infarcts and osteomyelitis. Bone scintigraphy, eventually in combination with bone marrow scintigraphy, can assist the clinician in the differentiation of aseptic bone infarcts versus secondary osteomyelitis. Based on the presented case scintigraphic results for bone infarcts, osteomyelitis and special scintigraphic pattern seen in sickle cell disease are presented. Furthermore, problems regarding the interpretation of the scintigraphies in relation to the delayed time after the beginning of pain attacks are discussed.

Prostacyclin-deficient mice develop ischemic renal disorders, including nephrosclerosis and renal infarction.

BACKGROUND: Prostacyclin (PGI2) is a short-lived endogenous inhibitor of platelet aggregation and a potent vasodilator and regulator of the growth of vascular smooth muscle cells. To study the role of PGI2 in the vascular system in vivo, PGI2-deficient (PGID) mice were established by genetic disruption of the PGI2 synthase gene. METHODS AND RESULTS: PGI2 synthase-null mice were generated by replacing the exons of PGI2 synthase gene that encodes for the catalytic site of the enzyme with a neomycin resistance gene. In these mice, PGI2 levels in the plasma, kidneys, and lungs were reduced, whereas thromboxane and prostaglandin E2 levels became elevated. Blood pressure and the amounts of urea nitrogen and creatinine in plasma of the PGID mice were significantly higher than those of wild-type mice (P<0.05). They developed progressive morphological abnormalities in the kidneys, accompanied by atrophy, surface irregularity, fibrosis, cyst, arterial sclerosis, and hypertrophy of vessel walls. Thickening of the thoracic aortic media and adventitia were observed in aged PGID mice. Importantly, these phenotypes have not been reported in PGI2 receptor-deficient mice. CONCLUSIONS: PGI2 deficiency resulted in the development of vascular disorders with the thickening of vascular walls and interstitial fibrosis, especially in mouse kidneys. The findings demonstrated in vivo that PGI2 is important in the homeostasis of blood vessels. Our established PGID mice are useful for studies on the initiation and development of vascular diseases, such as ischemic renal disorders with arterial sclerosis and infarction, and also for studies on the novel signaling pathway of PGI2.

Leiden factor V mutation in four patients with small bowel infarctions.

The Leiden factor V mutation is observed in 20% of unexplained lower limb venous thromboses and involves substitution of the arginine residue at position 506 by glutamine (R506Q). It is known to decrease the anticoagulant activity of activated protein C. This case report describes 4 cases of small bowel infarction (SBI) associated with the presence of this mutation. Two cases of arterial and 2 cases of venous SBI were observed. Extensive assessment excluded the usual causes of SBI and plasma hypercoagulation syndrome (antithrombin III, protein C, and protein S deficiency and myeloproliferative syndrome). An abnormal resistance to activated protein C was observed. Molecular analysis consisting of polymerase chain reaction amplification and digestion with MnlI showed that 2 patients were heterozygous and 2 were homozygous for the R506Q mutation. Despite familial history of thrombosis in only 1 patient, first- and second-degree relatives of 2 patients also had the presence of the mutation. Examination for the presence of abnormal resistance to activated protein C should be part of the etiological assessment of SBI. Its presence may warrant consideration of long-term anticoagulant therapy, especially for patients with shortened small bowel who are treated by home parenteral nutrition with deep venous access.

Intrarenal distribution of clusterin following reduction of renal mass.

Clusterin is a multifunctional protein isolated from a number of tissues in several different species. In a variety of renal diseases, clusterin appears in the glomerulus and tubules in association with the membrane attack complex of complement. It is also transiently expressed after several forms of acute renal injury. In this study, we examined the expression and intrarenal distribution of clusterin following subtotal renal ablation. Male rats were subjected to either 1-1/3 nephrectomy (1-1/3 NX), uninephrectomy (UNX) or sham operation (SHAM). Two weeks after surgery, clusterin mRNA was elevated in the 1-1/3 NX group (1-1/3 NX: 1215 +/- 88; UNX: 208 +/- 11; SHAM: 207 +/- 19 OD units; P less than 0.001). Clusterin mRNA increased between 3 and 24 hours after 1-1/3 NX, plateaued, and remained elevated for at least seven weeks. The increased clusterin mRNA in 1-1/3 NX was localized to the tissue adjacent to the infarctive scar (scar 858 +/- 173 vs. non-scar 98 +/- 27 OD units; P less than 0.001). Clusterin protein followed a similar pattern of localization, being increased in most tubules and some peritubular capillaries in the peri-infarct zone. Only occasional tubules were positive for clusterin in the renal tissue distant from the scar or in the kidneys of sham operated rats. Co-localization of clusterin and C5b-9 was not detected. Evidence for apoptosis was found in the peri-infarct zone but not elsewhere in 1-1/3 NX kidney or in the normal kidney following sham operation. Infarction of 1/3 of the left kidney without contralateral nephrectomy, a maneuver which eliminates the compensatory growth, and uremia seen with 1-1/3 NX still resulted in increased clusterin mRNA in the infarcted left kidney compared to the intact right kidney (LK: 790 +/- 112 vs. RK: 128 +/- 25 OD units; P less than 0.001), although the amount of clusterin mRNA was less than that found following 1-1/3 NX. In conclusion, persistently increased clusterin mRNA and protein was seen in the peri-infarct zone following 1-1/3 NX. This increased expression of clusterin may be playing a role in the ischemia-related apoptosis present in the scar-adjacent tissue.

Clonal immunoglobulin gene rearrangement in the infarcted lymph node syndrome.

The authors report a case of complete lymph node infarction in which a specific etiology could not be determined by morphologic or immunophenotypic studies; however, clonal rearrangement of the immunoglobulin gene was demonstrated by Southern blot hybridization of DNA extracted from the necrotic tissue. A subsequent lymph node biopsy later was diagnosed as malignant lymphoma, using morphologic, immunophenotypic and genotypic criteria. Identical clonally rearranged bands were present in DNA from both the infarcted nodal and the subsequent tissue biopsies. In the setting of lymph node necrosis, gene rearrangement studies may provide diagnostic information concerning clonality, even if morphologic and immunophenotypic studies are indeterminate for a lymphoproliferative process.

Hypercoagulability in a patient with Marfan syndrome.

A 39 year old man with Marfan syndrome presented with multiple pulmonary emboli and renal, hepatic, and splenic infarcts of unknown aetiology. The combination of thromboemboli and physical features initially suggested homocystinuria; however, laboratory examination showed no evidence for this disorder. Laboratory evaluation identified no coagulation abnormalities. This patient represents the unusual occurrence of hypercoagulability in a patient with Marfan syndrome.