LDL Apheresis: an effective and safe treatment for refractory hypercholesterolemia

Through the efforts of Edward H. Ahrens, LDL apheresis became available for the treatment of patients, often with familial hypercholesterolemia, who have no alternative therapy for severely elevated LDL cholesterol levels. In the U.S., the FDA has approved this treatment for individuals on maximum diet and drugs with an LDL cholesterol greater than 300 mg/dL or greater than 200 mg/dL with coronary artery disease. Unlike plasmapheresis, apolipoprotein B-containing lipoproteins (LDL, Lp(a), and VLDL) are selectively removed by heparin precipitation or columns containing dextran sulfate cellulose or antibodies to apolipoprotein B. The acute lowering of LDL-cholesterol by a typical 2 - 3 h treatment is up to 80%, and the time-averaged lowering in the 1 to 2 week interval between treatments is up to 50%, with very few side effects. The lowering of LDL-cholesterol and other cardioprotective effects of LDL apheresis have reduced chest pain, prevented new disability and prolonged life. Whole blood compatible columns in development offer the possibility of simpler and less expensive treatments.     

Aspartic proteinases in disease: a structural perspective

The aspartic proteinases are a family of enzymes involved in a number of important biological processes. In animals the enzyme renin has a hypertensive action through its role in the renin-angiotensin system. The retroviral aspartic proteinases, such as the HIV proteinase, are essential for maturation of the virus particle and inhibitors have a proven therapeutic record in the treatment of AIDS. The lysosomal aspartic proteinase cathepsin D has been implicated in tumorigenesis and the stomach enzyme pepsin, which plays a major physiological role in hydrolysis of acid-denatured proteins, is responsible for much of the tissue damage in peptic ulcer disease. Since aspartic proteinases also play major roles in amyloid disease, malaria and common fungal infections such as candidiasis, inhibitors to these enzymes are much sought after as potential therapeutic agents. In all aspartic proteinases, the catalytic aspartate residues are involved in an intricate arrangement of hydrogen bonds involving a solvent molecule which is presumed to be water. The catalytic mechanism is thought to involve nucleophilic attack of the active site water molecule on the scissile bond carbonyl generating a tetrahedral gem-diol intermediate. The design of inhibitors generally involves the use of short oligopeptides containing a transition state analogue which mimic this tetrahedral intermediate. The application of structure-based drug design to members of the aspartic proteinase family is the main subject of this review.     

New discoveries in prostate cancer biology and treatment. 5-9 December 2001, Naples, Florida, USA

Androgen independence and bone metastasis are lethal complications in patients with advanced prostate cancer. Presently, there is no cure for patients with androgen-independent prostate cancer. In order to develop more effective therapies for this disease, the molecular events involved in the development of androgen independence and bone metastasis must be elucidated and then targeted by therapeutic agents. Several studies presented at a recent conference on prostate cancer sponsored by the American Association for Cancer Research (AACR) provided evidence that prostate cancer metastasis to bone is mediated by the prostate cancer cell expression of molecules that allow the cells to invade, grow in and stimulate cells in the bone microenvironment resulting in an osteoblastic reaction. Androgen independence was reportedly mediated by an increased expression of survival genes following androgen ablation therapies and several molecular mechanisms involved in genetic instability. Treatment strategies are being designed to target some of the molecular events involved in androgen independence and bone metastasis. Targeting these molecular events with combinational therapies will hopefully delay the progression to androgen independence in patients with early stage disease, suppress the growth of androgen-independent cells in patients with advanced disease and enhance the chemosensitivity of androgen-independent cells.     

Optical biosensors in drug discovery

Optical biosensors that exploit surface plasmon resonance, waveguides and resonant mirrors have been used widely over the past decade to analyse biomolecular interactions. These sensors allow the determination of the affinity and kinetics of a wide variety of molecular interactions in real time, without the need for a molecular tag or label. Advances in instrumentation and experimental design have led to the increasing application of optical biosensors in many areas of drug discovery, including target identification, ligand fishing, assay development, lead selection, early ADME and manufacturing quality control. This article reviews important advances in optical-biosensor instrumentation and applications, and also highlights some exciting developments, such as highly multiplexed optical-biosensor arrays.     

Therapeutic LMP1 polyepitope vaccine for EBV-associated Hodgkin disease and nasopharyngeal carcinoma

Development of an epitope-based vaccination strategy designed to enhance Epstein-Barr virus (EBV)-specific CD8(+) cytotoxic T lymphocytes (CTLs) is increasingly being considered as a preferred approach for the treatment of EBV-associated relapsed Hodgkin disease (HD) and nasopharyngeal carcinoma (NPC). EBV-encoded latent membrane proteins, LMP1 and LMP2, are the only target antigens available for therapeutic augmentation of CTL responses in patients with HD and NPC. Here, we describe preclinical studies using a recombinant poxvirus vaccine that encodes a polyepitope protein comprising 6 HLA A2-restricted epitopes derived from LMP1. Human cells infected with this recombinant polyepitope construct were efficiently recognized by LMP1-specific CTL lines from HLA A2 healthy individuals. Furthermore, immunization of HLA A2/K(b) mice with this polyepitope vaccine consistently generated strong LMP1-specific CTL responses to 5 of the 6 epitopes, which were readily detected by both ex vivo and in vitro assays. More important, this polyepitope vaccine successfully reversed the outgrowth of LMP1-expressing tumors in HLA A2/K(b) mice. These studies provide an important platform for the development of an LMP-based polyepitope vaccine as an immunotherapeutic tool for the treatment of EBV-associated HD and NPC.     

The early repolarization normal variant electrocardiogram: correlates and consequences

PURPOSE: We compared the characteristics and outcomes of patients with "early repolarization" electrocardiograms (ECGs) with those who had normal ECGs. METHODS: In 1983 to 1985, we collected photocopies of 2234 selected ECGs from 73088 patients undergoing health examinations. Excluding 153 ECGs with missing data or that were judged to be abnormal, the remaining ECGs were reinterpreted in 2000 by cardiologists as showing early repolarization (n = 670), or being borderline (n = 330) or normal (n = 1081). Characteristics and outcomes of persons with early repolarization ECGs were compared with those who had normal ECGs using analysis of variance, logistic regression, or proportional hazards models. Information on exercise was available in 325 patients. RESULTS: Patients with early repolarization were more likely to be male (81% [n = 583] vs. 33% [n = 360]), <40 years old (60% [n = 441] vs. 37% [n = 403]), black (48% [n = 384] vs. 26% [n = 280]), and more athletically active (mean [+/- SD], 10.4 +/- 1.3 hours per week of activity vs. 6.4 +/- 1.2 hours per week of activity) than those with normal ECGs. Patients with early repolarization were not more likely to be hospitalized (hazard ratio [HR] = 1.0; 95% confidence interval [CI]: 0.9 to 1.2) or to die (HR = 0.8; 95% CI: 0.6 to 1.2) during follow-up than those with normal ECGs. Outpatient diagnoses were not more common in those with early repolarization; arrhythmias were actually less common (P <0.01). CONCLUSION: Although especially prevalent in young, athletic, black men, early repolarization is not rare in other patients. The long-term prognosis of early repolarization is benign.     

Darier's disease: epidemiology,pathophysiology, and management

Darier's disease is a rare cutaneous disease with an autosomal dominant mode of inheritance. Greasy papules and plaques arise on the seborrheic areas and in the flexures and almost all patients have nail abnormalities. Acantholysis and dyskeratosis are the typical histological findings. The underlying defect is a result of mutations in the ATP2A2 gene on chromosome 12q23-24 that encodes for a sarco/endoplasmic reticulum calcium ATPase (SERCA 2). Acantholysis is thought to result from desmosome breakdown. Darier's disease is an example of a dominantly inherited disease caused by haplo-insufficiency. Oral retinoids are the most effective treatment but their adverse effects are troublesome. Topical retinoids, topical corticosteroids, surgery, and laser surgery have their advocates but evidence for efficacy is sparse.     

Modulatory effects of melatonin on behavior, hemolymph metabolites, and neurotransmitter release in crayfish

Melatonin affects a variety of circadian processes such as behavior and neurotransmitter release in vertebrates. Crayfish melatonin production occurs in the eyestalks, and the cycle of production may change seasonally. To date, however, melatonin's roles and mechanisms of action in crustacean physiology are unclear. We injected melatonin or saline into crayfish in scotophase and monitored activity and hemolymph glucose/lactate over 24 h in early spring. Crayfish were significantly more active in photophase versus the expected scotophase, and had concurrent glucose/lactate peaks. Melatonin reversed the activity pattern, causing a scotophase activity peak, but not the glucose/lactate patterns. This study was repeated in late summer, during which control activity and glucose/lactate levels were elevated in scotophase. Melatonin decreased the amplitude of scotophase activity and glucose/lactate, eliminating activity and glucose cycles. We also injected melatonin or saline at various times of day in early summer and monitored locomotor activity for 1 h. Controls had high activity at 1200 (mid-photophase) and 2100 h (early scotophase), and melatonin increased activity at 1200 h but decreased it at 2100 h. Melatonin also increased activity at 1500 h but not 1800 h (late photophase). Next, we examined the influence of melatonin on crayfish neurophysiology. Melatonin (10 microM) enhanced synaptic transmission at the neuromuscular junction (NMJ). The presynaptic action resulted in more vesicles being released during evoked stimulation. Our study indicates that melatonin may have a phylogenetically conserved role in the transduction of circadian information in invertebrates as in vertebrates. Behavioral and physiological effects may be mediated by modulation of central pathways, enhanced at the peripheral level via neuromodulation of the NMJ.     

Ontogeny of calcitonin receptor mRNA and protein in the developing central nervous system of the rat

In this study, the expression of receptors for calcitonin (CTR), the CTR C1a and C1b isoforms, was investigated during development of the fetal rat central nervous system (CNS) by using in situ hybridization and immunohistochemistry. Coincident expression with both techniques was evident. Immunohistochemical evidence for the expression of the C1a isoform alone was found. Expression was first observed at embryonic day 12/13 (E12/E13) within and adjacent to the ventricular zones known to include primary matrices of proliferation, in regions of the preoptic area, anterior and posterior hypothalamus, anterior and posterior pons, medulla, and spinal cord. At later times, with the decline in the density of immunoreactivity at these loci (E15), expression in primary matrices was found later at distinct loci within the ventricular zones of cerebellum (E17), and at E19, the tectum, lateral ventricle, and cortical subplate. By E19, the density of staining had increased and was widespread throughout the expanding CNS. In the rostral domains, moderate to high density was found in the external plexiform layer; the medial preoptic area and nucleus; the ventromedial, dorsomedial, and arcuate hypothalamic nuclei; and the lateral and posterior hypothalamic areas. In the midbrain, similar levels of expression were noted in the central nucleus of raphe; the deep mesencephalic, dorsal raphe, and laterodorsal tegmental nuclei; and the ventral periaqueductal gray. In the pons, positive loci included the locus coeruleus and the gigantocellular and pontine reticular nuclei. In the medulla, high expression was evident in the gigantocellular, intermediate, magnocellular, and medullary reticular, spinal trigeminal and cuneate nuclei; and the nucleus tractus solitarius. In the spinal cord, moderate to high density of staining was found in the ventral, dorsal, and lateral horns, and in the ventral, dorsal, and cuneate funiculi. On the other hand, transitory expression was found in the diagonal band, bed nucleus of the stria terminalis, amygdala, and the lateral mamillary and anterobasal nuclei of the hypothalamus. These studies indicate a role for CTR in the activation of some premigratory neuroblasts in the CNS as well as a possible role later in an undefined function associated with mature neurons of particular nuclei.