CADASIL in Arabs: clinical and genetic findings

Background  

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is increasingly recognized as an inherited arterial disease leading to a step-wise decline and eventually to dementia. CADASIL is caused by mutations in NOTCH3 epidermal growth factor-like repeat that maps to chromosome 19. CADASIL cases have been identified in most countries of Western and Central Europe, the Americas, Japan, Australia, the Caribbean, South America, Tanzania, Turkey, South Africa and Southeast Asia, but not in Arabs.     

A B220(-), CD19(-) population of B cells in the peripheral blood of quasimonoclonal mice

We describe a new population of non-naive B cells in the peripheral blood of quasimonoclonal (QM) mice. Surface Ig of switched isotypes is expressed, but not B220 nor CD19. These cells are larger and denser than naive B cells but smaller than blasts or plasma cells; they do not stain with syndecan, a marker for plasma cells. Telomerase, which is usually expressed in B cell blasts, was not present in this population. We sorted the switched, idiotype-positive, B220(-) B cells from the peripheral blood of QM mice and sequenced Ig H chain and lambda L chain cDNA. There were many point mutations but no V gene replacements, gene conversions or other type of diversifications. As they express switched isotypes and have mutated their Ig genes, cells in the B220(-), CD19(-) population must have been in an immune response and we suggest that it includes the memory B cell subset.     

Specific suppression of anti-DNA productionin vitro

To investigate the regulation of anti-DNA antibody production, we generated anti-DNA-specific suppressor cells by exposing normal human T cells and a small percentage of adherent cells to high concentrations of DNA. These cells suppressed the production of anti-DNA by both autologous peripheral blood mononuclear cells (PBMC) and allogeneic PBMC derived from systemic lupus erythematosus (SLE) patients. Anti-DNA production was suppressed significantly more than anti-RNA, antitetanus, or total immunoglobulin production. Specific suppression was enhanced by increasing the numbers of DNA-primed CD8⁺ cells and was obliterated by irradiation of the DNA-primed cells. In contrast to T cells from normal individuals, T cells obtained from two intensively studied SLE patients were unable to generate specific suppressor cells for anti-DNA production in both autologous and allogeneic test systems. Despite this defect, these patients were still capable of generating specific suppressor cells for antibody production directed against an exogenous antigen, tetanus toxoid.     

Coping with dental treatment: The potential impact of situational demands

Coping strategies and anxiety responding of dental patients were studied in order to test the generalizability of previous findings based on volunteer blood donors. State and trait coping measures were administered once, and a process coping scale was administered at three points throughout treatment. Self-report, behavioral observation, and psychophysiological measures of anxiety were sampled for the same periods as process coping. Findings included the replication of a negative relationship between avoidant coping and patient anxiety ratings. Fluctuations in coping were evident across periods, and impact of situational demands and constraints was introduced as an explanation for these variations. A method for direct assessment of coping consistency was introduced. On the basis of the replicable associations with anxiety measures, the ability to detect changes in coping within a situation, and the ability to provide direct evidence of coping consistency, the use of process methodology for coping assessment is encouraged.This research was conducted while the first author was supported by funding from the Medical Research Council of Canada.Portions of this research were presented at the annual convention of the Society of Behavioral Medicine, Philadelphia, 1984.     

A model of electrical activity and cytosolic calcium dynamics in vascular endothelial cells in response to fluid shear stress

A mathematical model is proposed to describe the intracellularCa ²⁺ (Ca _i) transient and electrical activity of vascular endothelial cells (VEC) elicited by fluid shear stress (τ). The intracellularCa ²⁺ store of the model VEC is comprised of aCa _i-sensitive (sc) and an inositol (1,4,5)-trisphosphate (IP ₃)-sensitive compartment (dc). The dc [Ca ²⁺] is refilled by the sc whose [Ca ²⁺] is the same as extracellular [Ca ²⁺].IP ₃ produced by the τ-deformed mechanoreceptors discharges the dcCa ²⁺ into the cytosol. The increase of cytosolic[Ca ²⁺] inducesCa ²⁺ release (CICR) from the sc. The raisedCa _i activates aCa _i-activatedK ⁺ current (I _{K, Ca}) and inhibitsIP ₃ production. The cell membrane potential is determined byI _{K, Ca}, voltage-dependentNa ⁺ andK ⁺ currents. Steady τ>0.1 dyne/cm² elicits aCa _i varies sigmoidally withLog ₁₀(τ) with a maximal peakCa _i of 150 nM at τ=4 dynes/cm². Step increases of τ fail to elicit aCa ²⁺ response in cells previously stimulated by a lower shear. TheCa ²⁺ response gradually decreases with repetitive τ stimuli. Pulsatile shear elicits two to three times higherCa _i and hyperpolarizes the cell more than steady shear of the same magnitude. The simulatedCa ²⁺ responses to τ are quantitatively and qualitatively similar to those observed in cultured VEC. The model provides a possible explanation of why the vasodilating stimulus is greater for pulsatile flow than for nonpulsatile flow.     

Two unusual benign lesions of the neck masquerading as malignancy on fine-needle aspiration cytology

Two cases of unusual benign tumors of the neck are described, both of which were initially misdiagnosed on cytology as carcinomas. Fine-needle aspiration findings in each case demonstrated a pleomorphic population of cells including bizarre multi-nucleated giant cells, the latter raising the false impression of malignancy. However, on review the cytological appearances of the tumors, a pleomorphic lipoma and a carotid body tumor, were characteristic. the correct diagnosis in each case would have been made or suggested if the pathologist had been familiar with the cytologic features characteristic of the lesion and the differential diagnosis of the head and neck tumors. in addition, the point is made that adequate clinical information is essential for the pathologist if all relevant conditions are not to be missed in the differential diagnosis.     

Quinidine blockade of calcium-activated potassium channels in dissociated gastric smooth muscle cells

The effects of quinidine, an antiarrhythmic alkaloid, on potassium-selective channels in enzymatically dissociated gastric smooth muscle cells fromRana pipiens andBufo marinus were investigated using excised patches and the patch-clamp technique. The predominant potassium channel in these cells is the calcium- and voltage-activated maxi-K channel with a single-channel conductance > 100 pS. Applications of quinidine (100–600 M) resulted in resolvable rapid flickerings between the open and blocked states with a corresponding reduction in open channel amplitude and an increase in open channel noise. The currentvoltage curves in the presence of internal quinidine and symmetrical potassium gradients displayed inward rectification. The time-constant of open-time distributions was found to decrease with increasing quinidine concentrations and membrane depolarization. The power-density spectrum of the channel current noise induced by internal quinidine showed a second Lorentzian component with a corner frequency larger than 300 Hz, suggesting that the noise is caused by rapid fluctuations between the open and blocked states. Apparent dissociation constants of 253 M and 209 M for membrane potentials of +20 mV and –60 mV, respectively, were obtained for the quinidine-induced blockade of Ca²⁺-activated K⁺ channels in these smooth muscle cells. Another potassium-selective channel with a single-channel conductance of 40 pS was completely blocked in the presence of 100 M qunidine. However, a 15 pS potassium channel was not affected by quinidine but was reversibly blocked by tetraethylammonium. Quinidine (500 M) was also observed to decrease the opening probability of a 40 pS potassium channel fromBufo marinus without affecting its channel amplitude. Thus, quinidine appears to have diverse mechanisms of action on potassium-selective channels in smooth muscle cells, ranging from totally ineffective to highly selective, as a slow blocker for some channels and as intermediate and fast blockers for others.     

Characterization of proteins encoded by the Epstein-Barr virus transactivator gene BMLF1

Epstein-Barr virus (EBV) encodes a gene product in the BamHI-M leftward reading frame 1 (BMLF1) that functions as a promiscuous transactivator acting upon many other enhancer-promoter combinations. This protein has been studied by producing a polyclonal rabbit antiserum directed against a LacZ-BMLF1 fusion protein that was synthesized in Escherichia coli. Western blotting was employed to demonstrate that this antiserum specifically detected the BMLF1 proteins in E. coli, monkey, mouse, or B cells transfected with this gene, and in EBV-positive B cells chemically induced to produce this protein. In these induced B cells, two major proteins of 50 and 60 kDa and several minor antigens were detected by these antibodies. Transfection of an expression vector containing the BMLF1 coding sequence resulted in the synthesis of only the 50 kDa proteins. These major products were phosphorylated in vivo and were localized to the cell nucleus. Only the larger 60-kDa antigen was specifically induced to be synthesized by a different EBV encoded transactivator, the BZLF1 gene product. Chemical induction of lymphocytes latently infected with EBV resulted in the synthesis of both the 60- and 50-kDa forms of the BMLF1 transactivator. Two major forms of this EBV-encoded transactivator have been detected. The 60-kDa form is presumably derived from the BSLF2-BMLF1 open reading frame while the smaller antigens, 50 kDa size, appear to be made only by the BMLF1 open reading frame. These two forms of the transactivator are differently regulated and the functional significance of this remains to be explored.     

In vitro studies of human prostatic epithelial cells: attempts to identify distinguishing features of malignant cells

Recent advances in culture techniques have enabled routine establishment and propagation of epithelial cells derived from normal and malignant tissues of the human prostate. Comparative studies of the responses of normal and cancer-derived cell populations to various growth and differentiation factors in vitro were undertaken to examine the possibility that cancer cells might respond differentially. Clonal growth assays in serum-free medium demonstrated that optimal proliferation of normal as well as cancer cell strains was generally dependent on the presence of cholera toxin, epidermal growth factor, pituitary extract, hydrocortisone, insulin, and high levels of calcium in the culture medium, and on the use of collagen-coated dishes. Only one cancer strain responded aberrantly to epidermal growth factor and hydrocortisone. Putative differentiation factors (transforming growth factor-beta and vitamin A) inhibited the growth of all normal and cancer strains. The origin of a cancer-derived cell strain that responded similarly to normal strains was verified by positive labeling with a prostate cancer-specific antibody, validating the conclusion from these studies that normal and cancer prostatic epithelial cells are not distinguishable on the basis of responses to the tested factors.     

HIV accessory proteins and surviving the host cell

Human immunodeficiency virus generates the accessory proteins Nef, viral infectivity factor (Vif), viral protein R, and viral protein U or viral protein X during viral replication in host cells. Although the significance of these accessory proteins is often lost in vitro, they are essential for viral pathogenesis in vivo. Therefore, these proteins have much potential as antiviral targets. Recent data reveal Vif perturbs an ill-defined antiviral pathway in host cells allowing HIV replication. These data highlight a common feature among HIV accessory proteins in manipulating the host to aid viral pathogenesis. Therefore, these new insights into Vif and other HIV accessory proteins are reviewed, emphasizing host cell interactions and new targets for therapeutic intervention.