Clinical variability of Fanconi anemia (type C) results from expression of an amino terminal truncated Fanconi anemia complementation group C polypeptide with partial activity

Fanconi anemia (FA) is an autosomal recessive disease characterized by congenital anomalies, aplastic anemia, and cancer susceptibility. Mutations within the FA complementation group C (FAC) gene account for approximately 14% of diagnosed FA cases. Two mutations, one in exon 1 (delG322) and one in exon 4 (IVS4 + 4 A to T), account for 90% of known FAC mutations. The delG322 mutation results in a mild FA phenotype, while the IVS4 + 4 A to T mutation results in severe FA phenotype. To determine the molecular basis for this clinical variability, we analyzed patient-derived cell lines for the expression of characteristic mutant FAC polypeptides. All cell lines with the delG322 mutation expressed a 50-kD FAC polypeptides, FRP-50 (FAC-related protein), shown to be an amino terminal truncated isoform of FAC reinitiated at methionine 55. All cell lines with the IVS4 + 4 A to T mutation lacked FRP-50. Overexpression of a cDNA encoding FRP-50 in an FA(C) cell line resulted in partial correction of mitomycin C sensitivity. In conclusion, expression of an amino terminal truncated FAC protein accounts, at least in part, for the clinical heterogeneity among FA(C) patients.     

Outcomes following cardiopulmonary resuscitation in an emergency department of a low- and middle-income country

Background

Cardiopulmonary resuscitation (CPR) is a key component of emergency care following cardiac arrest. A better understanding of factors that influence CPR outcomes and their prognostic implications would help guide care. A retrospective analysis of 800 adult patients that sustained an in- or out-of-hospital cardiac arrest and underwent CPR in the emergency department of a tertiary care facility in Karachi, Pakistan, between 2008 and 15 was conducted.

Methods

Patient demographics, clinical history, and CPR characteristics data were collected. Logistic regression model was applied to assess predictors of return of spontaneous circulation and survival to discharge. Analysis was conducted using SPSS v.21.0.

Results

Four hundred sixty-eight patients met the study’s inclusion criteria, and overall return of spontaneous circulation and survival to discharge were achieved in 128 (27.4%) and 35 (7.5%) patients respectively. Mean age of patients sustaining return of spontaneous circulation was 52 years and that of survival to discharge was 49 years. The independent predictors of return of spontaneous circulation included age ≤?49 years, witnessed arrest, ≤?30 min interval between collapse-to-start, and 1–4 shocks given during CPR (aOR (95% CI) 2.2 (1.3–3.6), 1.9 (1.0–3.7), 14.6 (4.9–43.4), and 3.0 (1.4–6.4) respectively), whereas, age ≤?52 years, bystander resuscitation, and initial rhythm documented (pulseless electrical activity and ventricular fibrillation) were independent predictors of survival to discharge (aOR (95% CI) 2.5 (0.9–6.5), 1.4 (0.5–3.8), 5.3 (1.5–18.4), and 3.1 (1.0–10.2) respectively).

Conclusion

Our study notes that while the majority of arrests occur out of the hospital, only a small proportion of those arrests receive on-site CPR, which is a key contributor to unfavorable outcomes in this group. It is recommended that effective pre-hospital emergency care systems be established in developing countries which could potentially improve post-arrest outcomes. Younger patients, CPR initiation soon after arrest, presenting rhythm of pulseless ventricular tachycardia and ventricular fibrillation, and those requiring up to four shocks to revive are more likely to achieve favorable outcomes.

     

A two-stage immunoradiometric assay with 125I-staphylococcal protein A for the detection of antibodies and complement on human blood cells

A sensitive two-stage immunoradiometric assay (IRMA) using unlabeled specific antiglobulin sera followed by binding of radiolabeled staphylococcal protein A has been developed for detection of human IgG, IgM, IgA and complement C3 on human blood cells. In an experimental model system, purified human immunoglobulins (Ig) were coupled onto red blood cells, platelets, and leukocytes. The Ig-coated red blood cells were analyzed in parallel by three methods: the radioimmune antiglobulin test with radiolabeled anti-Ig; the radiolabeled staphyloccal protein A test, and the IRMA. Of the three methods evaluated, the latter was found to be sensitive and the easiest to perform. The applicability of the IRMA was established by investigating a group of 14 selected patients with autoimmune warm type hemolytic anemia. We observed that the IRMA detected cell-bound antibodies (IgG and/or IgM) in several cases where conventional assays yielded negative results.     

Donor leukocyte infusions for multiple myeloma

Donor leukocyte infusion (DLI) has well-documented activity in CML, but the role of DLI in other diseases is less well defined. To evaluate the strategy in multiple myeloma (MM) we evaluated 25 MM patients from 15 centers who were treated with DLI. Patients with persistent or recurrent disease after allogeneic BMT received DLI from the original marrow donor (23 matched related, one mismatched family, and one matched unrelated). Chemotherapy was given before DLI in three patients. Two of 22 patients responded completely to DLI alone and three patients responded to the combination of DLI and chemotherapy. Nine patients who had not had sufficient disease control after DLI were given additional DLIs; five of these patients had either complete (two) or partial (three) responses. Thirteen of 25 evaluable patients developed acute GVHD and 11 of 21 evaluable patients developed chronic GVHD; all responders developed GVHD. No patients developed post-DLI pancytopenia. Four patients had responses which lasted >1 year after DLI, three patients had responses which lasted <1 year, and three patients had ongoing responses but with follow-up <1 year. In conclusion, DLI has anti-myeloma activity but the strategy is limited by no response or short duration of response in a significant percentage of patients and by significant GVHD in the majority of the responders.     

Sex, age, and regional differences in L-type calcium current are important determinants of arrhythmia phenotype in rabbit hearts with drug-induced long QT type 2

In congenital and acquired long QT type 2, women are more vulnerable than men to torsade de pointes. In prepubertal rabbits (and children), the arrhythmia phenotype is reversed; however, females still have longer action potential durations than males. Thus, sex differences in K(+) channels and action potential durations alone cannot account for sex-dependent arrhythmia phenotypes. The L-type calcium current (I(Ca,L)) is another determinant of action potential duration, Ca(2+) overload, early afterdepolarizations (EADs), and torsade de pointes. Therefore, sex, age, and regional differences in I(Ca,L) density and in EAD susceptibility were analyzed in epicardial left ventricular myocytes isolated from the apex and base of prepubertal and adult rabbit hearts. In prepubertal rabbits, peak I(Ca,L) at the base was 22% higher in males than females (6.4+/-0.5 versus 5.0+/-0.2 pA/pF; P<0.03) and higher than at the apex (6.4+/-0.5 versus 5.0+/-0.3 pA/pF; P<0.02). Sex differences were reversed in adults: I(Ca,L) at the base was 32% higher in females than males (9.5+/-0.7 versus 6.4+/-0.6 pA/pF; P<0.002) and 28% higher than the apex (9.5+/-0.7 versus 6.9+/-0.5 pA/pF; P<0.01). Apex-base differences in I(Ca,L) were not significant in adult male and prepubertal female hearts. Western blot analysis showed that Ca(v)1.2alpha levels varied with sex, maturity, and apex-base, with differences similar to variations in I(Ca,L); optical mapping revealed that the earliest EADs fired at the base. Single myocyte experiments and Luo-Rudy simulations concur that I(Ca,L) elevation promotes EADs and is an important determinant of long QT type 2 arrhythmia phenotype, most likely by reducing repolarization reserve and by enhancing Ca(2+) overload and the propensity for I(Ca,L) reactivation.     

Serum leptin concentrations during severe protein-energy malnutrition: correlation with growth parameters and endocrine function

Circulating leptin, insulin, insulin-like growth factor-I (IGF-I), cortisol, and albumin concentrations and the growth hormone (GH) response to provocation were measured in 30 children with severe protein-energy malnutrition (PEM), 20 with marasmus and 10 with kwashiorkor, as well as 10 age-matched normal children (body mass index [BMI] >50th and <90th percentile for age and sex) and 10 prepubertal obese children (BMI >95th percentile for age and sex). Patients with PEM had a significantly lower BMI, midarm circumference (MAC), and skinfold thickness (SFT) compared with the age-matched control group. Basal cortisol and GH concentrations were significantly higher in the malnourished groups versus controls. Leptin and IGF-I were significantly lower in the marasmic and kwashiorkor groups versus normal children. Fasting insulin levels were significantly decreased in the kwashiorkor group compared with marasmic and normal children. The BMI correlated significantly with leptin (r = .77, P < .001), basal insulin (r = .61, P < .001), and IGF-I (r = .77, P < .001) and negatively with basal GH (r = -.52, P < .001). These findings suggest that during prolonged nutritional deprivation, the decreased energy intake, diminished subcutaneous fat mass, and declining insulin (and possibly IGF-I) concentration suppress leptin production. In support of this view, serum leptin levels were positively correlated with triceps, scapular, and abdominal SFT (r = .763, .75, and .744, respectively, P < .0001) in all of the children. Moreover, basal insulin and circulating IGF-I were correlated significantly with leptin concentrations (r = .47 and .62, respectively, P < .001). Basal levels of cortisol and GH were significantly elevated in the 2 groups with severe PEM. It is suggested that low leptin levels can stimulate the hypothalamic-pituitary-adrenal (HPA) axis and possibly the hypothalamic-pituitary-GH axis to maintain the high cortisol and GH levels necessary for effective lipolysis to ensure a fuel (fatty acids) supply for the metabolism of brain and peripheral tissue during nutritional deprivation. In summary, during prolonged PEM, the decreased synthesis of IGF-I and the low level of insulin and/or its diminished effect due to an insulin-resistant status in the presence of high circulating GH and cortisol levels ensure substrate diversion away from growth toward metabolic homeostasis. Leptin appears to be an important signal in the process of metabolic/endocrine adaptation to prolonged nutritional deprivation.     

Reversible posterior leukoencephalopathy in a patient with non-Hodgkin's lymphoma after treatment with CHOP

Reversible posterior leukoencephalopathy syndrome is a newly characterised and increasingly recognized clinico-radiologic syndrome. Underlying conditions that reportedly trigger this syndrome include hypertensive encephalopathy, eclampsia, renal failure, and immunosuppressive drug therapy with cyclosporine, tacrolimus and interferon alpha. We describe a 51-year-old woman with non-Hodgkin's lymphoma treated with conventional CHOP chemotherapy. Eight days after this treatment she developed severe headache, bilateral visual loss and focal seizures with secondary generalization. Neurologic examination showed confusion, cortical blindness, and left hemiparesis with hyperreflexia and sensory loss. A cranial T2-weighted magnetic resonance imaging revealed increased signal intensity in the occipital and frontal lobes in both hemispheres and right parietal lobe. A diagnosis of reversible posterior leukoencephalopathy was made. She presented a favourable outcome with conservative treatment with mannitol and phenytoin. A new cranial scanning showed nearly complete resolution of the abnormalities. To the best of our knowledge, this is the first case of reversible posterior leukoencephalopathy in a patient treated with standard-dose CHOP. In this patient, we confirm the theoretical pathophysiologic mechanisms suggested explaining how these drugs can cause the syndrome.     

Neuropathy caused by cisplatin. 7 cases including one with an autopsy study

The clinical, electrophysiological and histopathological features in seven cases of cisplatinum peripheral neuropathy are reported and compared with the literature data. The neuropathy appears for an average intake of 500 mg/m2 of DDP. The symptoms are those of a symmetric, distal, predominantly sensitive neuropathy of an axonal type with major involvement of proprioception. Neurological improvement is poor after withdrawal of the drug. A post mortem study performed in one case showed a degeneration of the posterior column in the cord and residual nodules of Nageotte in a lumbar spinal ganglion. The systematic study of the tendon reflexes and distal pallesthesia in subjects treated with the drug, may reveal the neuropathy before the onset of the most disabling symptoms (paresthesia, ataxia, pain, Lhermitte's sign).     

Redistribution of the Lamin B1 genomic binding profile affects rearrangement of heterochromatic domains and SAHF formation during senescence

Senescence is a stress-responsive form of stable cell cycle exit. Senescent cells have a distinct gene expression profile, which is often accompanied by the spatial redistribution of heterochromatin into senescence-associated heterochromatic foci (SAHFs). Studying a key component of the nuclear lamina lamin B1 (LMNB1), we report dynamic alterations in its genomic profile and their implications for SAHF formation and gene regulation during senescence. Genome-wide mapping reveals that LMNB1 is depleted during senescence, preferentially from the central regions of lamina-associated domains (LADs), which are enriched for Lys9 trimethylation on histone H3 (H3K9me3). LMNB1 knockdown facilitates the spatial relocalization of perinuclear H3K9me3-positive heterochromatin, thus promoting SAHF formation, which could be inhibited by ectopic LMNB1 expression. Furthermore, despite the global reduction in LMNB1 protein levels, LMNB1 binding increases during senescence in a small subset of gene-rich regions where H3K27me3 also increases and gene expression becomes repressed. These results suggest that LMNB1 may contribute to senescence in at least two ways due to its uneven genome-wide redistribution: first, through the spatial reorganization of chromatin and, second, through gene repression.     

Potential deleterious role of anti‐Neu5Gc antibodies in xenotransplantation

Human beings do not synthesize the glycolyl form of the sialic acid (Neu5Gc) and only express the acetylated form of the sugar, whereas a diet‐based intake of Neu5Gc provokes a natural immunization and production of anti‐Neu5Gc antibodies in human serum. However, Neu5Gc is expressed on mammal glycoproteins and glycolipids in most organs and cells. We review here the relevance of Neu5Gc and anti‐Neu5Gc antibodies in the context of xenotransplantation and the use of animal‐derived molecules and products, as well as the possible consequences of a long‐term exposure to anti‐Neu5Gc antibodies in recipients of xenografts. In addition, the importance of an accurate estimation of the anti‐Neu5Gc response following xenotransplantation and the future contribution of knockout animals mimicking the human situation are also assessed.