Cutaneous reactive hyperaemia is unaltered by dietary nitrate supplementation in healthy humans

The purpose of this study was to determine whether nitrate supplementation augments cutaneous reactive hyperaemia. Seven participants were tested pre‐ and postnitrate supplementation (25 ml beetroot juice); participants consumed one shot per day for 3 days. Participants were instrumented with two microdialysis fibres: control (Ringer's solution) and NO synthase inhibition (20 mM L‐NAME). Skin blood flow was measured via laser‐Doppler flowmetry (LDF). A blood pressure cuff was placed on the experimental arm and inflated to 250 mmHg for 5 mins to occlude arterial inflow. The cuff was released, and the resultant reactive hyperaemia was measured. Blood pressure was continuously measured via plethysmography from a finger on the non‐experimental arm. Cutaneous vascular conductance was calculated (LDF/MAP) and normalized to maximal vasodilatation (%CVC_max). Only diastolic blood pressure was reduced following nitrate supplementation (71 ± 2 vs. 66 ± 1 mmHg; P<0·05). There was no effect of nitrate supplementation on peak reactive hyperaemia at control (Pre: 52 ± 3 vs. Post: 57 ± 2%CVC_max) or L‐NAME (Pre: 52 ± 2 vs. Post: 59 ± 4%CVC_max) sites. There was no effect of nitrate supplementation on total reactive hyperaemia at either control (Pre: 4197 ± 943 vs. Post: 4523 ± 1040%CVC_max * sec) or L‐NAME (Pre: 5108 ± 997 vs. Post: 5694 ± 1002%CVC_max * sec) sites. These data suggest cutaneous reactive hyperaemia is unaffected by dietary nitrate supplementation in healthy humans.     

Influence of a Methanogenic Flora on the Breath H2 and Symptom Response to Ingestion of Sorbitol or Oat Fiber

Background and Objectives: We investigated the possibility that a variant of the normal colonic flora, a high concentration of methanogeas, influences the host's response to ingestion of nonabsorbable, fermentable materials. Methods: To better evaluate symptomatic and breath H₂ and methane (CH₄) responses, subjects were placed on a basal diet (primarily rice and hamburger) that contained minimal amounts of nonabsorbable, fermentable substrate. A breath CH₄/H₂ ratio of greater or less than 1 on the second day of the basal diet was used to categorize subjects as high (N = 9) or low (N = 25) CH₄ producers. After stabilization of the breath gas excretion (day 3 or 4 on the basal diet), the subjects ingested either sorbitol (8.8 g) or oat fiber (10.2 g). Results: The low CH₄ producers had a signficantly higher ( p < 0.05) breath H₂ concentration than the high producers on the basal diet and after ingestion of sorbitol (27.1 ± 2.7 ppm vs 15.8 ± 3.6 ppm) or oat fiber (13.1 ± 0.08 ppm vs 9.6 ± 1.2 ppm). Low producers of methane reported significantly increased bloating and cramping after sorbitol ingestion and increased bloating after fiber ingestion, whereas high CH₄ producers reported no signficant increase in these symptoms. Conclusion: The presence of a methanogenic flora is associated with a reduced symptomatic response to ingestion of nonabsorbable, fermentable material in healthy subjects. Manipulation of the normal flora could be of therapeutic value in nonmethanogenic patients with irritable bowel syndrome.     

Immunophenotypic transformation from acute undifferentiated leukemia to Burkitt's-like acute lymphoblastic leukemia

Progression of more differentiated to less differentiated malignant phenotypes has been described infrequently during the natural evolution or at relapse of treated hematopoietic malignancies. This report describes an unusual instance of immunophenotypic transformation from an immunologically undifferentiated acute leukemia to a leukemia that at relapse possessed morphologic and immunologic markers characteristic of a Burkitt's-like acute lymphoblastic leukemia. A 26-year-old man initially presented with pancytopenia and a bone marrow diffusely replaced with blast cells morphologically most consistent with a French-American-British L2 subclassification. The surface immunophenotype of the blasts at diagnosis showed HLA-DR surface antigen but no myeloid, lymphoid, or immunoglobulin determinants. Despite successful induction and ongoing consolidation chemotherapy, the patient had a relapse five months after diagnosis; blast cells at relapse demonstrated marked cytoplasmic vacuolation consistent with a Burkitt's-like L3 acute lymphoblastic transformation. Immunophenotypic analysis revealed the presence of restricted immunoglobulin determinants (mu heavy chain and kappa light chain), as well as two separate B lineage surface determinants (BA-1 and B-1). Immunophenotypic transformations may reflect the presence of either a multiclonal or multipotent leukemic population; documentation of the frequency of such transformations and genomic analysis of the transformed subpopulations may be helpful in furthering the understanding of molecular mechanisms involved in leukemogenesis.     

Age-dependent neurological phenotypes in a mouse model of PRRT2-related diseases

Paroxysmal kinesigenic dyskinesia is an episodic movement disorder caused by dominant mutations in the proline-rich transmembrane protein PRRT2, with onset in childhood and typically with improvement or resolution by middle age. Mutations in the same gene may also cause benign infantile seizures, which begin in the first year of life and typically remit by the age of 2 years. Many details of PRRT2 function at the synapse, and the effects of mutations on neuronal excitability in the pathophysiology of epilepsy and dyskinesia, have emerged through the work of several groups over the last decade. However, the age dependence of the phenotypes has not been explored in detail in transgenic models. Here, we report our findings in heterozygous and homozygous Prrt2 knockout mice that recapitulate the age dependence of dyskinesia seen in the human disease. We show that Prrt2 deletion reduces the levels of synaptic proteins in a dose-dependent manner that is most pronounced at postnatal day 5 (P5), attenuates at P60, and disappears by P180. In a test for foot slippage while crossing a balance beam, transient loss of coordination was most pronounced at P60 and less prominent at age extremes. Slower traverse time was noted in homozygous knockout mice only, consistent with the ataxia seen in rare individuals with biallelic loss of function mutations in Prrt2. We thus identify three age-dependent phenotypic windows in the mouse model, which recapitulate the pattern seen in humans with PRRT2-related diseases.

     

Regulation of erythropoietin production in a human hepatoblastoma cell line

Production of immuno and biologically active erythropoietin was documented to occur in the human hepatoblastoma cell line HepG-2. The expression of the erythropoietin gene was further verified by Northern blot analysis using a single stranded RNA probe. In vitro studies showed that erythropoietin production by these cells was not stimulated by hypoxia or cobalt chloride, but was related to the proliferative activity of the cells in culture. In addition it was found that the secretion of erythropoietin was almost completely abrogated by tunicamycin, an inhibitor of N-linked glycosylation. This effect of tunicamycin was also observed in a permanently transfected cell line that secretes erythropoietin in large quantities.     

An alternative extrinsic pathway of human blood coagulation

To study the interrelationships of the major human coagulation pathways, factor X activation in normal and various deficient human plasmas was evaluated when clotting was triggered by dilute rabbit or human thromboplastin. Various dilutions of thromboplastin were added to plasma samples containing 3H-labeled factor X, and the time course of factor X activation was determined. At a 1/250 dilution of rabbit brain thromboplastin the rate of factor X activation in factor VIII or factor IX deficient plasma was only 10% of the activation rate seen for normal or factor XI deficient plasma. Reconstitution of the deficient plasmas with factors VIII or IX, respectively, restored normal factor X activation. Similar results were obtained when various dilutions of human thromboplastin replaced the rabbit thromboplastin. From these experiments, it is inferred that normal activation of factor X in plasma due to dilute thromboplastin requires factors VII, IX and VIII. An alternative extrinsic pathway that involves factors VII, IX, and VIII may be a major physiologic extrinsic pathway, and this pathway may help to explain the clinical observations of bleeding diatheses in patients deficient in factors IX or VIII.     

Clinical features and outcome of T-cell acute lymphoblastic leukemia in childhood with respect to alterations at the TAL1 locus: a Pediatric Oncology Group study

Alteration of the TAL1 locus is the most common nonrandom genetic defect in childhood T-cell acute lymphoblastic leukemia (T-ALL). To determine if rearrangements of the TAL1 proto-oncogene confer a distinct leukemic phenotype, we studied leukemic peripheral blood or bone marrow samples from 182 children with newly diagnosed T-ALL enrolled on Pediatric Oncology Group treatment protocols. Forty-eight (26%) of the samples had a local rearrangement of the TAL1 locus. Demographic and clinical features were compared for patient subgroups with and without TAL1 rearrangements. The only clinical correlates that were significantly associated with TAL1 gene rearrangements were higher white blood cell count (P = .017) and higher hemoglobin (P = .007) at diagnosis. Immunophenotypically, samples with altered TAL1 were more likely to be CD2+ (P = .001) and lack CD10 (cALLa) expression (P = .007) than those without the rearrangement. There was a trend toward improved event-free survival (EFS) in patients with TAL1 rearrangements (4-year EFS was 44% +/- 7% for patients without the rearrangements v 59% +/- 11% for those with rearrangements), but the difference was not significant (P = .34). The role of TAL1 in leukemogenesis has yet to be clearly defined, and the prognostic significance of TAL1 gene rearrangements in T-ALL deserves further study.     

Impaired glucose tolerance and elevated blood pressure in low birth weight, nonobese, young south african adults: early programming of cortisol axis

Low birth weight is associated with increased cardiovascular and metabolic disorders in adult life, although the mechanisms of this effect remain uncertain. There is one report of increased morning plasma cortisol levels in an elderly low birth weight cohort, but whether this is primary or secondary to other aspects of the phenotype is unclear. We investigated the association between low birth weight and glucose intolerance, blood pressure, and dyslipidemia in young, nonobese adults from a community undergoing the health transition with a high prevalence of both noncommunicable diseases and low birth weight. Additionally, we investigated whether altered basal and stimulated cortisol levels as a marker of hypothalamic-pituitary-adrenal responsiveness or cortisol metabolism were associated with low birth weight in these young adults. Twenty-year-old, historically disadvantaged, urbanized South Africans (n = 137) with birth weights either below the 10th percentile [underweight for age (UFA)] or between the 25th and 75th percentiles [appropriate for gestational age (AFA)] had anthropometry, blood pressure, lipid levels, and glucose tolerance measured. In a subset (n = 62), 0900 h plasma cortisol concentrations, cortisol responses to 1 microg ACTH, and urinary glucocorticoid metabolites were measured. The mothers of UFA infants were themselves lighter and had a lower body mass index (P: = 0. 0016). At age 20 yr, although the UFA group was still smaller and lighter, with a lower body mass index, they had higher fasting plasma glucose levels (P: = 0.047), and a greater proportion demonstrated glucose intolerance (11.9% vs. 0%; P: < 0.01). The UFA group also had higher systolic [UFA, 126.0 +/- 13.3 (+/-SD); AFA, 122.0 +/- 11.7 mm Hg; P: = 0.007] and diastolic (72.3 +/- 8.4 vs. 69. 5 +/- 8.7 mm Hg; P: = 0.02) blood pressures, after covarying for current weight and gender. Plasma cortisol levels determined at 0900 h were higher in the UFA group (484.9 +/- 166.3 vs. 418.6 +/- 160.6 nmol/L) and showed a greater plasma cortisol response to low dose ACTH stimulation (area under the curve for cortisol: UFA, 77,238 +/- 19,511; AFA, 66,597 +/- 16,064 nmol/L.min; P: = 0.04). In conclusion, the link between low birth weight and adult glucose intolerance and blood pressure elevation occurs in young adults in a high risk, disadvantaged population despite a lack of full catch-up growth. Moreover, cortisol axis activation is an early feature in the process linking low birth weight with adult cardiovascular and metabolic disease and is not dependent upon adult obesity or full catch-up growth, at least in this population undergoing the health transition.