A truncating PET100 variant causing fatal infantile lactic acidosis and isolated cytochrome c oxidase deficiency

Isolated mitochondrial complex IV (cytochrome c oxidase) deficiency is an important cause of mitochondrial disease in children and adults. It is genetically heterogeneous, given that both mtDNA-encoded and nuclear-encoded gene products contribute to structural components and assembly factors. Pathogenic variants within these proteins are associated with clinical variability ranging from isolated organ involvement to multisystem disease presentations. Defects in more than 10 complex IV assembly factors have been described including a recent Lebanese founder mutation in PET100 in patients presenting with Leigh syndrome. We report the clinical and molecular investigation of a patient with a fatal, neonatal-onset isolated complex IV deficiency associated with multiorgan involvement born to consanguineous, first-cousin British Asian parents. Exome sequencing revealed a homozygous truncating variant (c.142C>T, p.(Gln48*)) in the PET100 gene that results in a complete loss of enzyme activity and assembly of the holocomplex. Our report confirms PET100 mutation as an important cause of isolated complex IV deficiency outside of the Lebanese population, extending the phenotypic spectrum associated with abnormalities within this gene.     

Monocytoid B-cell lymphoma: its evolution and relationship to other low- grade B-cell neoplasms

Monocytoid B-cell lymphoma (MBCL) is a newly recognized B-cell neoplasm of uncertain histogenesis. The cytologic features of the neoplastic monocytoid B lymphocytes are virtually identical to those of hairy cell leukemia (HCL). As with HCL, progression of MBCL to a higher histologic grade is very unusual. However, whereas circulating leukemic cells are a characteristic feature of HCL, peripheral blood involvement has not been reported in MBCL. We recently studied a patient with MBCL of the spleen and axillary lymph nodes who developed peripheral blood involvement by MBCL cells. Unlike the cells of HCL, the circulating MBCL cells exhibited strong acid phosphatase activity that was tartrate sensitive. The leukemic cells had the antigenic phenotype IgM lambda, CD20+, CD11c+, CD5-, CD25(TAC)-, and PCA-1-. Immunogenetic studies of both lymph node and peripheral blood cells revealed identical immunoglobulin heavy-chain gene rearrangements. When compared with a series of HCL, the immunophenotype was similar except for the absence of PCA-1 and TAC. Progression of the MBCL to a large cell lymphoma, also expressing IgM lambda, was documented in an abdominal lymph node of this patient. Therefore, although rare, peripheral blood involvement by lymphoma cells may occur during the course of MBCL and should be distinguished from HCL with cytochemical and immunophenotypic studies. In addition, comparison of the clinical, pathologic, and immunologic features of MBCL with those of other low-grade B-cell neoplasms suggests that a close lineage relationship exists between MBCL and HCL.     

Treatment with interleukin-3 plus granulocyte-macrophage colony- stimulating factors improves the selectivity of Ara-C in vitro against acute myeloid leukemia blasts

Hematopoietic growth factors (HGFs) interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) individually have been shown to increase the percentage of acute myeloid leukemia (AML) blasts in S phase and enhance the cytotoxic effects of Ara-C against these blasts in culture. We compared in vitro the effects of a combined treatment with GM-CSF (10 ng/mL) plus IL-3 (10 ng/mL) on the metabolism and cytotoxicity of Ara-C in normal bone marrow mononuclear cells (NBMMC) and AML blasts. NBMMC from six healthy volunteers and AML blasts from 10 patients were incubated for 20 hours with or without IL- 3 plus GM-CSF, followed by a concurrent treatment with Ara-C for 4 additional hours. Exposure to the HGFs and Ara-C produced significantly higher intracellular Ara-CTP levels as well as higher Ara-CTP/dCTP pool ratios in AML blasts as compared with NBMMC. Treatment with HGFs resulted in [3H] Ara-C DNA incorporation that was significantly higher in AML blasts versus NBMMC. This selective improvement of Ara-C metabolism in AML blasts was associated with an enhanced Ara-C-mediated leukemia colony-forming unit (CFU) growth inhibition. In contrast, exposure to HGFs resulted in an improved colony growth of normal CFU granulocyte-monocyte and CFU-granulocyte, erythroid, monocyte, megakaryocyte. These in vitro studies indicate that a combined treatment with IL-3 plus GM-CSF may improve the selectivity of Ara-C against AML blasts.     

Elevated ANA titers in patients with severely abnormal gastrointestinal motility

We studied a group of six patients with clinical, radiological, and/or manometric features of severely abnormal gastrointestinal motility. Symptoms suggestive of esophageal, small bowel, or colonic involvement were present from 1 1/2 to 40 years. All patients had elevated antinuclear antibody (ANA) titers. None had clinical or radiographic features suggestive of progressive systemic sclerosis or other connective tissue diseases. Two patients had pathologic examinations of intestinal specimens, and these did not show changes suggestive of progressive systemic sclerosis. We conclude that patients with severe gastrointestinal motility disorders can have elevated ANA titers without features of progressive systemic sclerosis or other connective tissue diseases.This study was supported by the National Institutes of Health grant AM 25965 and grant RR 59 from the General Research Centers Program, Division of Research Resources, National Institutes of Health.     

Trypsinogen Activation Peptides (TAP) in Peritoneal Fluid as Predictors of Late Histopathologic Injury in Necrotizing Pancreatitis of the Rat

The levels of trypsinogen activation peptides(TAP) were quantified by ELISA immunoassay in acutepancreatitis of the rat and compared to the degree oflate histopathological sequelae and exocrine functional impairment 4 and 12 weeks after the acute phaseof the disease. For this purpose acute pancreatitis ofdifferent severity was induced using a suitable ratmodel recently described. Forty five surviving animals were studied. The level of TAP inperitoneal exudate measured 3 and 6 hr afterpancreatitis induction correlated well with the amountof the late histopathological injury at the end of thecorresponding observation period (at 4 weeks after 3 hr: r =0.75, P = 0.003, after 6 hr: r = 0.72, P = 0.005,Pearson; and at 12 weeks after 3 hr: r = 0.86, P =0.0001, after 6 hr: r = 0.84, P = 0.0001, Pearson). A negative correlation of TAP with the impairmentof exocrine function was found only at 4 weeks for thesecretion of total protein (r = –0.76 after 3 hr;r = –0.62 after 6 hr) and for exocrine function (r = –0.67 after 3 hr, r = –0.57 after6 hr), but not at 12 weeks after acute pancreatitis. Nocorrelation with plasma amylase and lipase was found. Weconclude that quantitation of TAP in ascites provides an accurate prediction of late histopathologicsequelae. Pancreatic exocrine function could bepredicted by TAP assay only in the early stage afterpancreatitis induction (eg, four weeks). In later stages of the disease (eg, 12 weeks) remainingpancreatic tissue seems to compensate for any exocrinedeficits that have occurred.     

Autonomic function test during the COVID-19 pandemic: the Stanford experience

Clinical Autonomic Research -     

Development of large numbers of mast cells at sites of idiopathic chronic dermatitis in genetically mast cell-deficient WBB6F1-W/Wv mice

The normal skin and other tissues of adult mast cell-deficient WBB6F1- W/Wv or WCB6F1-Sl/Sld mice contain less than 1.0% the number of mast cells present in the corresponding tissues of the congenic normal (+/+) mice. As a result, genetically mast cell-deficient WBB6F1-W/Wv or WCB6F1-Sl/Sld mice are widely used for studies of mast cell differentiation and function. We found that mast cells developed at sites of idiopathic chronic dermatitis in WBB6F1-W/Wv mice and that the number of mast cells present in the skin of WBB6F1-W/Wv mice was proportional to the severity of the dermatitis (in ear skin, there were 33 +/- 4 mast cells/mm2 of dermis at sites of severe dermatitis v 9 +/- 3 at sites of mild dermatitis, 0.8 +/- 0.3 in skin without dermatitis, and 100 +/- 7 in the normal skin of congenic WBB6F1-+/+ mice; in back skin, the corresponding values were 2.0 +/- 0.6, 1.1 +/- 0.9, 0.025 +/- 0.025, and 26.2 +/- 3.2). The development of mast cells was a local, not systemic, consequence of the dermatitis. Thus, WBB6F1-W/Wv mice with severe dermatitis lacked mast cells in skin not showing signs of dermatitis and also in the peritoneal cavity, stomach, cecum, and tongue. Idiopathic chronic dermatitis was not associated with the local development of mast cells in WCB6F1-Sl/Sld mice, a mutant whose mast cell deficiency is due to a mechanism distinct from that of WBB6F1-W/Wv mice. These findings may have implications for understanding the nature of the mast cell deficiency in WBB6F1-W/Wv and WCB6F1-Sl/Sld mice and for the use of these mutants to analyze mast cell differentiation and function.