Apoptosis of late-stage erythroblasts in megaloblastic anemia: association with DNA damage and macrocyte production

An in vitro model of folate-deficient erythropoiesis has been developed using proerythroblasts isolated from the spleens of Friend virus-infected mice fed an amino acid-based, folate-free diet. Control proerythroblasts were obtained from Friend virus-infected mice fed the same diet plus 2 mg folic acid/kg diet. Our previous studies showed that, after 20 to 32 hours of culture in folate-deficient medium with 4 U/mL of erythropoietin, the folate-deficient proerythroblasts underwent apoptosis, whereas control erythroblasts survived and differentiated into reticulocytes over a period of 48 hours. The addition of folic acid or thymidine to the folate-deficient medium prevented the apoptosis of the folate-deficient erythroblasts, thereby implicating decreased thymidylate synthesis as the main cause of apoptosis in the folate-deficient erythroblasts. In the study reported here, we examined intracellular folate levels, uracil misincorporation into DNA, p53 and p21 proteins, and reticulocyte formation in erythroblasts cultured in folate-deficient or control medium. In all experiments, the folate-deficient erythroblasts cultured in folate-deficient medium gave results that varied significantly from folate-deficient erythroblasts cultured in control medium or control erythroblasts cultured in either folate-deficient or control media. Folate-deficient erythroblasts cultured in folate-deficient medium had marked decreases in all coenzyme forms of folate that persisted throughout culture, increased uracil misincorporation into DNA, persistent accumulations of p53 and p21, and decreased reticulocyte production but increased size of individual reticulocytes. A model of folate-deficient erythropoiesis based on apoptosis of late stage erythroblasts is presented. This model provides explanations for the clinical findings in megaloblastic anemia.     

Severe mental illness and HIV-related medical and neuropsychiatric sequelae

Medical and neuropsychiatric sequelae of HIV infection present a spectrum of diagnostic and treatment challenges to mental health clinicians. Both HIV and the many opportunistic infections that manifest in patients due to their immunocompromised state also can affect the central nervous system (CNS). Thus, mental health clinicians need to be familiar with the diagnosis and management of HIV-related medical and psychiatric complications. This article provides an overview of the CNS-related manifestations resulting from HIV disease, including HIV-related dementia, psychotic disorders, delirium, CNS opportunistic infections and tumors, systemic abnormalities, psychoactive substances, and the adverse effects of certain medical treatments. Treatment strategies for individuals with HIV disease and comorbid severe mental illness are outlined and recommendations for future research are offered.     

Rate of HIV-1 decline following antiretroviral therapy is related to viral load at baseline and drug regimen

OBJECTIVES AND DESIGN: The dynamics uf viral decline following the initiation of antiretroviral treatment were studied in 29 HIV-1-infected patients participating in a two-arm trial comparing immediate (group A: ritonavir, zidovudine and lamivudine) and delayed (group B: ritonavir supplemented by zidovudine and lamivudine on day 21) triple therapy. Parameters underlying viral dynamics were estimated using mathematical models tailored to these treatment protocols. RESULTS: The decline in plasma HIV-1 density between day 0 and 21 was steeper in group A (-2.27+/- 0.46 log10) than group B (-1.87+/-0.56 log10). In a subset of patients amenable to full mathematical analysis, a short-lived productively infected cell compartment (producing approximately 97% of total virions) decayed with a half-life of 1.0-2.5 days, whereas a long-lived infected cell compartment decayed with a half-life of 18.8-32.8 days. Estimates for the time for the elimination of virus from these two cell populations ranged from 474 to 802 days. The rate of loss of productively infected CD4+ T cells was positively correlated with baseline viral load in group A and in the combined dataset. CONCLUSIONS: These results suggest that HIV-infected cell populations may have a faster turnover in patients with higher viral loads due to higher infection rate parameters, higher rates of virus production, or lower virus clearance rates.     

Metal-thiolate clusters in the C-terminal domain of human neuronal growth inhibitory factor (GIF)

Neuronal growth inhibitory factor (GIF), a metallothionein-like protein (metallothionein-3), impairs the survival and neurite formation of cultured neurons. Native GIF contains 4 Cu(I) and three Zn(II) ions organized in homometallic metal-thiolate clusters. However, the cluster localization is not known. In this study, the metal-thiolate clusters formed with monovalent and divalent metal ions in the C-terminal domain of human GIF [GIF(32-68)] containing 11 cysteines were investigated. The cluster formation was followed by using electronic absorption, circular dichroism (CD), and magnetic circular dichroism (MCD) spectroscopy, and in the case of Cu(I) complexes also by luminescence spectroscopy at 77 K. Spectroscopic studies on the Cu(I)-GIF(32-68) complexes showed the successive formation of two air-sensitive Cu4S8-9- and Cu6S11-clusters. With Zn(II) and Cd(II) ions, a well-defined M4S11-cluster is formed in which each metal ion is tetrahedrally coordinated by cysteine thiolates. In the 113Cd NMR spectra of 113Cd4-GIF(32-68), recorded at 293 and 323 K, all four 113Cd resonances at 672.8, 620.9, 629.6, and 564.2 ppm were observed only at 323 K. Their detection at elevated temperature indicates a conformational flexibility of this domain. Evidence for the existence of a Cd6-GIF(32-68) complex, contaning two more weakly bound Cd(II) ions, was also obtained. The formation of this complex requires the transformation of some originally terminal thiolates of the Cd4S11-cluster to bridging thiolates, suggesting a more accessible cluster structure. Such properties of Cd4-GIF(32-68) have not been observed with the Cd4S11-cluster in the isolated alpha-domain (amino acids 31-61) of metallothioneins. The significance of Cu- and Zn-clusters for the structure of native GIF is discussed.