Genes for rare idiopathic generalized epilepsies: BFNC.
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Epilepsy, Generalized↗
Biomedical subjects
N Singh
Publications and source records attributed to N Singh.
Hypocalcemic effect of phototherapy - reply
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Journal Article↗
Umbilical cord fall in preterm and term newborns in vaginal and caesarean deliveries.
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Cesarean Section↗
Central nervous system lesions in liver transplant recipients: prospective assessment of indications for biopsy and implications for management.
BACKGROUND: Precise diagnosis of central nervous system (CNS) lesions in liver transplant recipients remains problematic. Brain biopsies are often not feasible as a result of coagulopathy. We sought to determine whether selected clinical or radiologic characteristics can predict the likely etiology of CNS lesions in liver transplant recipients and thus obviate the need for diagnostic brain biopsies. METHODS: A 4-year prospective, observational, cohort study was conducted at liver transplant centers at four geographically diverse medical institutions. A total of 1730 consecutive liver transplant recipients were evaluated for CNS lesions; 60 patients with radiologically documented CNS lesions comprised the study sample. RESULTS: Vascular events (52%, 31/60), infections (181%, 11/60), immunosuppressive associated leukoencephalopathy (12%, 7/60), central pontine myelinolysis (8%, 5/60), and malignancy (3%, 2/60) were the predominant etiologies of CNS lesions. CNS lesions were most likely to occur within 30 days of transplantation (43%, 26/60); central pontine myelinolysis, subdural hematoma, acute infarcts, and Aspergillus brain abscesses were the predominant etiologies during this time. All brain abscesses were fungal; 73% (8/11) of these patients concurrently had documented extraneural (pulmonary) infection as a result of the same fungal pathogen. Thus, a diagnostic brain biopsy is not warranted in these patients. Patients on dialysis were more likely to have ischemic or infectious CNS lesions (P=0.03). Vascular events were more likely to occur in repeat transplant recipients (P=0.03). Twenty-five percent (15/60) of the CNS lesions occurred more than 1 year after transplantation; small vessel ischemic lesions, malignancy, or non-Aspergillus fungal brain abscesses accounted for all such lesions. CONCLUSIONS: A presumptive etiologic diagnosis can be established in a vast majority of CNS lesions in liver transplant recipients based on identifiable presentation that includes time of onset, unique risk factors, and neuroimaging characteristics. Empiric therapy of brain abscesses in liver transplant recipients should include antifungal and not antibacterial agents.
Adult↗
Effects of inhaled nitric oxide and oxygen in high-altitude pulmonary edema.
BACKGROUND: High-altitude pulmonary edema (HAPE) is characterized by pulmonary hypertension, increased pulmonary capillary permeability, and hypoxemia. Treatment is limited to descent to lower altitude and administration of oxygen. METHODS AND RESULTS: We studied the acute effects of inhaled nitric oxide (NO), 50% oxygen, and a mixture of NO plus 50% oxygen on hemodynamics and gas exchange in 14 patients with HAPE. Each gas mixture was given in random order for 30 minutes followed by 30 minutes washout with room air. All patients had severe HAPE as judged by Lake Louise score (6.4+/-0.7), PaO2 (35+/-3. 1 mm Hg), and alveolar to arterial oxygen tension difference (AaDO2) (26+/-3 mm Hg). NO had a selective effect on the pulmonary vasculature and did not alter systemic hemodynamics. Compared with room air, pulmonary vascular resistance fell 36% with NO (P<0.001), 23% with oxygen (P<0.001 versus air, P<0.05 versus NO alone), and 54% with NO plus 50% oxygen (P<0.001 versus air, P<0.005 versus oxygen and versus NO). NO alone improved PaO2 (+14%) and AaDO2 (-31%). Compared with 50% oxygen alone, NO plus 50% oxygen had a greater effect on AaDO2 (-18%) and PaO2 (+21%). CONCLUSIONS: Inhaled NO may have a therapeutic role in the management of HAPE. The combined use of inhaled NO and oxygen has additive effects on pulmonary hemodynamics and even greater effects on gas exchange. These findings indicate that oxygen and NO may act on separate but interactive mechanisms in the pulmonary vasculature.
Administration, Inhalation↗
Infectious complications occurring in liver transplant recipients receiving mycophenolate mofetil.
BACKGROUND: Mycophenolate mofetil (MMF) is a new immunosuppressive agent that is gaining widespread use in solid organ transplantation recipients. A comprehensive assessment of infectious complications after its use after liver transplantation has never been assessed. METHODS: Bacterial, fungal, and viral infections occurring after transplantation were compared for a cohort of consecutive liver transplant recipients who received MMF (because of suspected tacrolimus-related nephrotoxicity or neurotoxicity) and a cohort who did not receive the drug. All patients received a tacrolimus-based primary immunosuppressive protocol. RESULTS: Biopsy-proven acute rejection episodes within the first 6 months after transplant occurred in 6% of MMF-treated patients but in 30% of those who did not receive MMF (P=0.07). No significant differences were found in occurrence of cytomegalovirus infection or disease, Pneumocystis carinii, Aspergillus, or other fungal infection and hepatitis C virus recurrence between MMF-treated and untreated patients. Bacterial infections were more common in MMF-treated patients, but this cohort had a prolonged intensive care unit stay compared with patients who did not receive MMF. None of the MMF-treated patients with bacterial infection had leukopenia. CONCLUSIONS: MMF use does not appear to be associated with an significantly increased risk of infection occurring after liver transplantation and is associated with fewer episodes of acute rejection.
Cohort Studies↗
Conversion of a radioresistant phenotype to a more sensitive one by disabling erbB receptor signaling in human cancer cells.
Inhibition of cell growth and transformation can be achieved in transformed glial cells by disabling erbB receptor signaling. However, recent evidence indicates that the induction of apoptosis may underlie successful therapy of human cancers. In these studies, we examined whether disabling oncoproteins of the erbB receptor family would sensitize transformed human glial cells to the induction of genomic damage by gamma-irradiation. Radioresistant human glioblastoma cells in which erbB receptor signaling was inhibited exhibited increased growth arrest and apoptosis in response to DNA damage. Apoptosis was observed after radiation in human glioma cells containing either a wild-type or mutated p53 gene product and suggested that both p53-dependent and -independent mechanisms may be responsible for the more radiosensitive phenotype. Because cells exhibiting increased radiation-induced apoptosis were also capable of growth arrest in serum-deprived conditions and in response to DNA damage, apoptotic cell death was not induced simply as a result of impaired growth arrest pathways. Notably, inhibition of erbB signaling was a more potent stimulus for the induction of apoptosis than prolonged serum deprivation. Proximal receptor interactions between erbB receptor members thus influence cell cycle checkpoint pathways activated in response to DNA damage. Disabling erbB receptors may improve the response to gamma-irradiation and other cytotoxic therapies, and this approach suggests that present anticancer strategies could be optimized.
Apoptosis↗
Kappa chain monoallelic demethylation and the establishment of allelic exclusion.
Allelic exclusion in kappa light-chain synthesis is thought to result from a feedback mechanism by which the expression of a functional kappa light chain on the surface of the B cell leads to an intracellular signal that down-regulates the V(D)J recombinase, thus precluding rearrangement of the other allele. Whereas such a feedback mechanism clearly plays a role in the maintenance of allelic exclusion, here we provide evidence suggesting that the initial establishment of allelic exclusion involves differential availability of the two kappa alleles for rearrangement. Analysis of kappa+ B-cell populations and of individual kappa+ B cells that have rearranged only one allele demonstrates that in these cells, critical sites on the rearranged allele are unmethylated, whereas the nonrearranged allele remains methylated. This pattern is apparently generated by demethylation that is initiated at the small pre-B cell stage, on a single allele, in a process that occurs prior to rearrangement and requires the presence in cis of both the intronic and 3' kappa enhancers. Taken together with data demonstrating that undermethylation is required for rearrangement, these results indicate that demethylation may actually underly the process of allelic exclusion by directing the initial choice of a single kappa allele for rearrangement.
Alleles↗
60 Hz magnetic field exposure induces DNA crosslinks in rat brain cells.
In previous research, we found an increase in DNA strand breaks in brain cells of rats acutely exposed to a 60 Hz magnetic field (for 2 h at an intensity of 0.5 mT). DNA strand breaks were measured with a microgel electrophoresis assay using the length of DNA migration as an index. In the present experiment, we found that most of the magnetic field-induced increase in DNA migration was observed only after proteinase-K treatment, suggesting that the field caused DNA-protein crosslinks. In addition, when brain cells from control rats were exposed to X-rays, an increase in DNA migration was observed, the extent of which was independent of proteinase-K treatment. However, the X-ray-induced increase in DNA migration was retarded in cells from animals exposed to magnetic fields even after proteinase-K treatment, suggesting that DNA-DNA crosslinks were also induced by the magnetic field. The effects of magnetic fields were also compared with those of a known DNA crosslink-inducing agent mitomycin C. The pattern of effects is similar between the two agents. These data suggest that both DNA-protein and DNA-DNA crosslinks are formed in brain cells of rats after acute exposure to a 60 Hz magnetic field.
Animals↗
Staphylococcus aureus nasal colonization and association with infections in liver transplant recipients.
BACKGROUND: Staphylococcus aureus has emerged as a leading cause of bacterial infections after liver transplantation. However, the role of nasal colonization in the development of S aureus infections has never been explored in liver transplant recipients. The objectives of this study were to determine whether nasal carriage of S aureus was a risk factor for S aureus infections in liver transplant recipients. METHODS: Over a 2-year period, 30 consecutive liver transplant recipients were studied. Beginning when the recipients were transplant candidates, nasal cultures were performed at each admission and monthly thereafter until discharge or death. RESULTS: Overall, 67% (20/30) of the patients were nasal carriers, 70% of the carriers had methicillin-resistant S aureus (MRSA), 15% had methicillin-sensitive S aureus, and 15% had both MRSA and methicillin-sensitive S aureus. Infections were significantly associated with the carrier state; 100% (9/9) of the infected patients were carriers as compared with 50% (11/21) of the noninfected patients (P=0.01). All infections were a result of MRSA, and 56% (5/9) of the infections were bacteremia. Median time to the onset of S aureus infections was 16 days after transplant. Pulse field gel electrophoresis (with digestion of S aureus with SmaI restriction enzyme) in seven infected patients demonstrated that the isolates from the anterior nares matched the invasive isolates in all cases. A total of 43% (3/7) of these infected patients shared the same restriction pattern. CONCLUSION: MRSA colonization of the anterior nares was a significant predictor of MRSA infections in liver transplant recipients. Infections occurred only in those colonized with MRSA and were a result of the endogenously colonizing S aureus strains in all cases.
Adult↗
Modulation of T cell cytokine profiles and peptide-MHC complex availability in vivo by delivery to scavenger receptors via antigen maleylation.
We have previously shown that conversion of proteins to scavenger receptor (SR) ligands by maleylation increases their immunogenicity. We now show that maleyl-Ag-immune spleen cells make relatively more IFN-gamma and less IL-4 or IL-10 than native Ag-immune cells. This is also reflected in the IgG1:IgG2a ratios in Abs generated in vivo. SR engagement on macrophages does not alter their surface levels of the adhesive/costimulatory molecules CD11a/CD18, CD11b/CD18, CD24, CD54, or CD40, nor does it enhance their ability to support anti-CD3-driven proliferation of naive T cells in vitro. Costimulatory molecules implicated in differential Th1/Th2 commitment--CD80, CD86, and IL-12--are not inducible by SR ligation. In addition to macrophages and dendritic cells, B cells also show receptor-mediated uptake and enhanced presentation of maleyl-Ags. Using a monoclonal T cell line to detect peptide-MHC complexes expressed on spleen cells in Ag-injected mice, we find that higher levels of these complexes are generated in vivo from maleyl-proteins and they persist longer than those generated from the native protein. Together, these data suggest that in certain situations, the levels of cognate ligand available and/or the time course of their availability may play a major role in determining the cytokine profiles of the responding T cells in addition to the costimulatory signals implicated so far.
Animals↗
Modulation of voltage-dependent Ca2+ channels in rabbit colonic smooth muscle cells by c-Src and focal adhesion kinase.
There is emerging evidence indicating that smooth muscle contraction and Ca2+ influx through voltage-dependent L-type Ca2+ channels are regulated by tyrosine kinases; however, the specific kinases involved are largely unknown. In rabbit colonic muscularis mucosae cells, tyrosine-phosphorylated proteins of approximately 60 and 125 kDa were observed in immunoblots using an anti-phosphotyrosine antibody and were identified as c-Src and focal adhesion kinase (FAK) by immunoblotting with specific antibodies. FAK co-immunoprecipitated with c-Src, and the phosphorylation of the c-Src.FAK complex was markedly enhanced by platelet-derived growth factor (PDGF) BB. The presence of activated c-Src in unstimulated cells was identified in cell lysates by immunoblotting with an antibody recognizing the autophosphorylated site (P416Y). In whole-cell patch-clamp studies, intracellular dialysis of a Src substrate peptide and anti-c-Src and anti-FAK antibodies suppressed Ca2+ currents by 60, 62, and 43%, respectively. In contrast, intracellular dialysis of an anti-mouse IgG or anti-Kv1.5 antibody did not inhibit Ca2+ currents. Co-dialysis of anti-c-Src and anti-FAK antibodies inhibited Ca2+ currents (63%) equivalent to dialysis with the anti-c-Src antibody alone. PDGF-BB enhanced Ca2+ currents by 43%, which was abolished by the anti-c-Src and anti-FAK antibodies. Neither the MEK inhibitor PD 098059 nor an anti-Ras antibody inhibited basal Ca2+ currents or PDGF-stimulated Ca2+ currents. The alpha1C subunit of the L-type Ca2+ channel co-immunoprecipitated with anti-c-Src and anti-phosphotyrosine antibodies, indicating direct association of c-Src kinase with the Ca2+ channel. These data suggest that c-Src and FAK, but not the Ras/mitogen-activated protein kinase cascade, modulate basal Ca2+ channel activity and mediate the PDGF-induced enhancement of L-type Ca2+ currents in differentiated smooth muscle cells.
Animals↗
Orthotopic liver transplantation in high-risk patients: risk factors associated with mortality and infectious morbidity.
BACKGROUND: One of the most controversial areas in patient selection and donor allocation is the high-risk patient. Risk factors for mortality and major infectious morbidity were prospectively analyzed in consecutive United States veterans undergoing liver transplantation under primary tacrolimus-based immunosuppression. METHODS: Twenty-eight pre-liver transplant, operative, and posttransplant risk factors were examined univariately and multivariately in 140 consecutive liver transplants in 130 veterans (98% male; mean age, 47.3 years). RESULTS: Eighty-two percent of the patients had postnecrotic cirrhosis due to viral hepatitis or ethanol (20% ethanol alone), and only 12% had cholestatic liver disease. Ninety-eight percent of the patients were hospitalized at the time of transplantation (66% United Network for Organ Sharing [UNOS] 2, 32% UNOS 1). Major bacterial infection, posttransplant dialysis, additional immunosuppression, readmission to intensive care unit (P=0.0001 for all), major fungal infection, posttransplant abdominal surgery, posttransplant intensive care unit stay length of stay (P<0.005 for all), donor age, pretransplant dialysis, and creatinine (P<0.05 for all) were significantly associated with mortality by univariate analysis. Underlying liver disease, cytomegalovirus infection and disease, portal vein thrombosis, UNOS status, Childs-Pugh score, patient age, pretransplant bilirubin, ischemia time, and operative blood loss were not significant predictors of mortality. Patients with hepatitis C (HCV) and recurrent HCV had a trend towards higher mortality (P=0.18). By multivariate analysis, donor age, any major infection, additional immunosuppression, posttransplant dialysis, and subsequent transplantation were significant independent predictors of mortality (P<0.05). Major infectious morbidity was associated with HCV recurrence (P=0.003), posttransplant dialysis (P=0.0001), pretransplant creatinine, donor age, median blood loss, intensive care unit length of stay, additional immunosuppression, and biopsy-proven rejection (P<0.05 for all). By multivariate analysis, intensive care unit length of stay and additional immunosuppression were significant independent predictors of infectious morbidity (P<0.03). HCV recurrence was of borderline significance (P=0.07). CONCLUSIONS: Biologic and physiologic parameters appear to be more powerful predictors of mortality and morbidity after liver transplantation. Both donor and recipient variables need to be considered for early and late outcome analysis and risk assessment modeling.
Adult↗
Causes of leukocytosis in liver transplant recipients: relevance in clinical practice.
BACKGROUND: Leukocytosis without a recognizable etiology often poses a diagnostic and therapeutic dilemma in transplant recipients. METHODS: Fifty consecutive episodes of leukocytosis in 47 liver transplant recipients were prospectively assessed. RESULTS: Leukocytosis was documented in 70% (33/47) of the patients, whereas 30% (14/47) of the patients never developed leukocytosis. Three distinctive etiologies accounted for 82% of the episodes. Thirty-two percent (16/50) of the episodes occurred between 1 and 3 days after transplantation, were unaccompanied by fever, and resolved spontaneously within 2 days. Infections accounted for 28% (14/50) of the episodes of leukocytosis; median time to onset was 25 days after transplantation, and fever occurred in 57%. In 22% (11/50) of the episodes, a characteristic leukocytosis occurred 7-14 days after transplantation (in the absence of documented infections or rejection) that was unaccompanied by fever, and resolved spontaneously without antibiotics; the platelet count of these patients was significantly higher than those of postoperative (P < 0.01) or infectious leukocytosis (P < 0.05). Resolution of pretransplant hypersplenism, with the release of sequestered splenic granulocytes and platelets, was the likely cause. Rejection and corticosteroid boluses accounted for 4% and 8% of the episodes, respectively. CONCLUSIONS: Timing of onset and awareness of the patterns of leukocytosis can be valuable in the evaluation of posttransplant leukocytosis. Stable patients with leukocytosis, but without fever or documented infections, in the immediate postoperative period and between 7 and 14 days after transplantation, need not be empirically treated with antibiotics.
Adult↗
Interferon-alpha for prophylaxis of recurrent viral hepatitis C in liver transplant recipients: a prospective, randomized, controlled trial.
BACKGROUND: In a randomized, controlled trial, we sought to determine whether prophylaxis with interferon-alpha for 6 months had an impact on rate, severity, and timing of onset of recurrent hepatitis C virus (HCV) hepatitis in liver transplant recipients and to assess whether interferon use was associated with rejection in liver transplant recipients. METHODS: Twenty-four consecutive liver transplant recipients with HCV were randomized after transplantation to receive either interferon-alpha (3 million U three times weekly) for 6 months or no prophylaxis; median follow-up was 874 days. RESULTS: Recurrent HCV hepatitis (histopathologically proven) developed in 50% (6 of 12) of the interferon-alpha patients versus 42% (5 of 12) of the control patients (P=NS). Severity of recurrence (as assessed by Knodell score on liver biopsies) also did not differ between the two groups (mean 4.0 for interferon-alpha patients versus 3.5 for control patients, P=NS). Interferon-alpha, however, significantly delayed the timing of occurrence of HCV hepatitis; recurrent HCV hepatitis developed a median of 408 days after transplant in the interferon-alpha group versus 193 days in the control group (P=0.05). No difference in graft or patient survival was demonstrated in the two groups. Rejection episodes, treated with corticosteroids, occurred in 50% (6 of 12) of patients in the interferon-alpha group versus 42% (5 of 12) in the control group (P=NS). Corticosteroid resistant rejection (requiring OKT3) occurred in only one study patient (in the control group). CONCLUSIONS: Interferon-alpha in liver transplant recipients for 6 months delayed the occurrence of HCV hepatitis, but did not decrease the incidence nor the severity of HCV hepatitis after transplantation. Interferon-alpha use was not associated with a higher incidence of rejection compared with the control patients.
Adult↗
The influence of hepatitis C virus genotypes on the outcome of liver transplantation.
BACKGROUND: The aim of this study was to report the influence of hepatitis C virus (HCV) genotypes and HLA matches on the outcome of liver transplantation, hepatitis recurrence, and progression to cirrhosis after transplantation. METHODS: HCV genotypes were determined from pretransplantation sera and/or liver explant tissues from 202 patients with HCV-related end-stage liver disease. One hundred fifty patients with known infecting genotype for whom posttransplantation biopsy specimens were available or who had normal results of liver injury tests constituted the group analyzed. Patients were followed up for up to 4.5 years. Hepatitis activity index scores at the time of disease recurrence were used to assess disease activity. Cirrhosis was diagnosed by using histological evidence. The number of HLA matches with respect to A, B, DR, and DQ loci was determined. RESULTS: The rates of hepatitis recurrence were 25% and 75% at 1 year and 4 years, respectively; Kaplan-Meier survival analysis did not reveal significant differences between the infecting genotypes with respect to overall rates of survival or recurrence of hepatitis. At hepatitis recurrence, hepatitis activity index scores did not differ between the genotype groups. The distribution of infecting genotypes among the 7 patients who developed cirrhosis is reflective of pretransplantation distribution. Neither HLA site-specific nor total matches affected the rates of survival or disease recurrence. CONCLUSIONS: The infecting HCV genotype had no influence on the incidence or severity of recurrent hepatitis, rate of survival, or development of cirrhosis. HLA matching does not influence transplantation outcome for HCV-related disease.
Adult↗
Evolution of a mammalian promoter through changes in patterns of transcription factor binding.
Previously, we identified evolutionarily derived changes in the pattern of nuclear factor binding to overlapping sites (termed A, B, and C, in proximal to distal order) within the promoter region of the murine D7Rp2e gene. In Mus domesticus, strong binding occurs at site B, with weak binding at sites A and C; in M. pahari, strong binding is observed at sites A and C, with weak binding at site B. The M. pahari-specific occupancy pattern is associated with repression of transcription. Presently, we have identified two interspecies changes, a single A --> G substitution within site B and a 7-bp indel within site C, that are primary determinants of the interspecies differences. These mutations alter both the pattern of binding site occupancy and the ability to repress transcription. The results are discussed in terms of a model involving a dynamic equilibrium between states of binding site occupancy, the nature of which can be modified during evolution.
Animals↗
Successful treatment of disseminated cryptococcosis in a liver transplant recipient with fluconazole and flucytosine, an all oral regimen.
Amphotericin B, with or without 5-flucytosine, is currently the therapy of choice for cryptococcal infections. However, amphotericin B, is nephrotoxic and requires long-term venous access for parenteral administration. The combination of fluconazole and flucytosine is synergistic in vitro against Cryptococcus. To date, however, the efficacy of fluconazole and flucytosine for cryptococcosis in liver transplant recipients has never been reported. We report a 66-year-old liver transplant recipient with disseminated invasive cryptococcus (presenting as cryptococcal subcutaneous abscess, osteomyelitis, and serum cryptococcal antigen titer of 1:32). The administration of amphotericin B for 3 weeks led to nephrotoxicity without any clinical response (persistent abscess without change in serum cryptococcal antigen titer). Fluconazole, at a dosage equivalent to 800 mg/day administered orally, and flucytosine, also given orally, led to a clinical response and a steady decline in serum cryptococcal antigen titer, which became negative at 6 weeks of therapy. The patient remains well 18 months after therapy. No adverse effects have been attributed to fluconazole or flucytosine. This combination obviates the nephrotoxicity and the need for parenteral access required for amphotericin B infusion, and it can be administered orally. The combination of fluconazole and flucytosine warrants future controlled trials for the treatment of cryptococcal infection in liver transplant recipients.
Administration, Oral↗