Phenotypic effect correlating with loss of a novel tumor suppressor gene: towards cloning by complementation

We intend to use a gene complementation approach to clone a tumor suppressor gene on mouse chromosome 2, the loss of which contributes to myeloid leukemia. An in vitro model system has been generated using a clonal cell line, in which tumorigenic chromosomal lesions have been selected along with myeloid differentiation. Among these lesions are deletions of chromosome 2. Comparison of subclones with deleted vs intact chromosomes 2 has allowed the identification of a growth related phenotypic pattern which correlates with the deletion, viz the retention of a marker of immature cells, resistance to inhibition by lipopolysaccharide (LPS), even in the presence of markers of mature myeloid cells, such as resistance to killing by apoptosis-inducing agents. The phenotype is shared by chromosome 2-deleted cell lines derived from conventional tumors. We have begun to investigate the mechanism of the phenotype. The LPS resistance does not correlate with lack of mRNA for CD14, a known cell surface receptor for this agent, or with failure to induce TNF alpha or nitric oxide synthase in response to its binding. The system should allow cloning of the gene using complementation of this phenotype in transfected cell lines.     

Inertial vestibular coding of motion: concepts and evidence

Central processing of inertial sensory information about head attitude and motion in space is crucial for motor control. Vestibular signals are coded relative to a non-inertial system, the head, that is virtually continuously in motion. Evidence for transformation of vestibular signals from head-fixed sensory coordinates to gravity-centered coordinates have been provided by studies of the vestibulo-ocular reflex. The underlying central processing depends on otolith afferent information that needs to be resolved in terms of head translation related inertial forces and head attitude dependent pull of gravity. Theoretical solutions have been suggested, but experimental evidence is still scarce. It appears, along these lines, that gaze control systems are intimately linked to motor control of head attitude and posture.     

Are trustworthiness and fairness enough? Contextual family therapy and the good family

The moral dimension of family therapy theory and practice has received increasing attention in recent years. Boszormenyi-Nagy was among the first to see that family therapy and moral questions are inseparable. His focus on relational ethics has helped us to reappropriate individual responsibility and accountability within a systemic context. Although contextual therapy has clearly enriched the field, we argue that its emphasis on trustworthiness and fairness provides a limited view of the good in family life and leads to three related problems. First, Boszormenyi-Nagy offers a compelling ethical vision of the family and then denies that he has done so, which undermines some of his key moral claims. Second, because fairness is defined subjectively, contextual therapy may not have the resources to deal with legitimate differences in family ideals. Third, the reliance on self-interest as the primary motive for trustworthy relating appears to be self-defeating. We offer a hermeneutic perspective that takes a broader approach to the good. It places greater emphasis on the social and historical context, deals squarely with different understandings of the good in family life, and recommends an approach to resolving these differences.     

Efficacy of itraconazole in the prevention of fungal infections among neutropenic patients with hematologic malignancies and intensive chemotherapy. A double blind, placebo controlled study

We studied the efficacy and safety of itraconazole for the prevention of fungal infection in neutropenic patients given cytotoxic chemotherapy for hematologic malignancies. Patients were randomly allocated to receive either itraconazole (200 mg bd) or placebo in addition to oral amphotericin B until the patient either developed fungal infection or had completed antileukemic treatment. Forty six patients (83 neutropenic episodes) treated with itraconazole and 46 placebo treated patients (84 neutropenic episodes) were evaluable. No specific toxicity was noted. Nine fungal infections developed in the itraconazole group, of which four were histologically or microbiologically proven and 15 in the patients given placebo (eight proven) (p < 0.12). All these patients received IV amphotericin B. The incidence of Candida albicans infections tended to be lower in the itraconazole group, but overall, there was no measurable improvement in the prevention of fungal infections and mortality by itraconazole.     

Inhibition by verapamil and diltiazem of agonist-stimulated contractile responses in mammalian ventricular cardiomyocytes

Secretin, vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) each exert potent positive contractile responses directly in rat ventricular cardiomyocytes. However, the contractile-coupling mechanisms associated with these responses have not been determined. In the present study, the involvement of L-type calcium channels in the contractile responses elicited by each peptide has been investigated using the selective antagonists at L-type calcium channels, verapamil and diltiazem. Ventricular cardiomyocytes, isolated from the hearts of adult rats, were stimulated to contract at 0.5 Hz in the presence of CaCl2 (2 mM) and adenosine deaminase (5U/ml). Cardiomyocytes were pre-incubated for 3 min prior to stimulation, in the absence of L-type calcium channel antagonist, and in the presence of verapamil (< or = 1 microM) or diltiazem (< or = 1 microM). Verapamil (< or = 1 microM) and diltiazem (< or = 1 microM) inhibited the contractile responses elicited by isoprenaline (100 nM) and forskolin (40 microM), used as positive controls, significantly, and in a concentration-dependent manner, but did not inhibit significantly the contractile response elicited by phenylephrine (2 microM), which was employed as a negative control. Verapamil (< or = 1 microM) and diltiazem (< or = 1 microM) inhibited the contractile responses to secretin (20 nM) and VIP (20 nM) significantly, and in a concentration-dependent manner, but did not inhibit the contractile response to CGRP. These data indicate that the positive contractile responses to secretin and VIP in mammalian ventricular cardiomyocytes involve the influx of calcium ion via L-type calcium channels, while the positive contractile response to CGRP does not.     

Anticomplementary activity in serum samples from patients with acute parvovirus B19 infection

Of 65 serum samples submitted for diagnostic purposes which proved to be anti-complementary by complement fixation test, 49 were parvovirus B19 IgM positive. Forty four of the 49 serum samples were from patients with arthropathy. Acute parvovirus B19 infection should be suspected when a patient has symptoms of disease of the joints and the serum is anticomplementary.     

Use of a modified Roux-en-Y procedure for treatment of pyloroduodenal obstruction in a horse

A modification of the Roux-en-Y anastomosis procedure was used to bypass a pyloroduodenal mass in a 12-year-old Arabian stallion. Clinical signs had consisted of a 4-week progression of ventral and hind limb edema, hypoproteinemia, fecal occult blood, intermittent abdominal pain, weight loss, and gastric reflux. On exploratory celiotomy, an obstructive mass was found in the pylorus and proximal portion of the duodenum. Gastrojejunostomy and duodenojejunostomy were performed by use of stapled side-to-side anastomosis techniques. Inaccessibility of the obstructed pyloric region prevented resection of the affected area.     

Consensus Conference on Platelet Transfusion, Royal College of Physicians of Edinburgh, 27-28 November 1997. Synopsis of background papers

The effects of 1-(2-amino-4-methanesulfonamidophenoxy)-2-[N-(3,4-dimethoxypheneth yl)-N-methylamino] ethane hydrochloride (KCB-328), in comparison with those of dofetilide, were studied on the action potentials (APs) of isolated guinea pig papillary muscles. KCB-328 (0.003-3 microM) concentration-dependently prolonged the AP duration at 90% repolarization (APD90) at 1- and 3-Hz pacing, and the concentration-response relations at 1 and 3 Hz resemble each other. Dofetilide (0.001-1 microM) also produced the concentration-dependent prolongation of APD90 but more pronouncedly at 1 than at 3 Hz, demonstrating the reverse frequency-dependent effect. KCB-328 at 0.03, 0.1, 0.3, and 1 microM increased APD90 by 11 +/- 1, 19 +/- 1, 25 +/- 1, and 29 +/- 1% at 3 Hz and by 9 +/- 1, 19 +/- 2, 27 +/- 2, and 33 +/- 2% at 1 Hz, respectively. Prolongation of the effective refractory period (ERP) by each drug is parallel to those of APD90 at each pacing frequency. KCB-328 modified neither the maximal velocity of depolarization, amplitude of AP, and resting membrane potential in the fast APs, nor any parameters of the slow APs. In a separate experiment, the effects of KCB-328 on the ERP of contractile response (ERPc) of excised guinea-pig papillary muscles also were studied at 1 and 3 Hz. KCB-328 (0.01-10 microM) lengthened the ERPc in a concentration-dependent and frequency-independent manner as in the electrophysiologic results. This frequency-independent ERPc prolongation by KCB-328 was not influenced by increased extracellular K+ concentration from 4 to 10 mM. These results suggest that KCB-328 might be a selective class III agent with effects that are relatively frequency independent.     

Atrial natriuretic peptide inhibits evoked catecholamine release by altering sensitivity to calcium

Natriuretic peptides are cyclized peptides produced by cardiovascular and neural tissues. These peptides inhibit various secretory responses such as the release of renin, aldosterone and autonomic neurotransmitters. This report tests the hypothesis that atrial natriuretic peptide reduces dopamine efflux from an adrenergic cell line, rat pheochromocytoma cells, by suppressing intracellular calcium concentrations. The L-type calcium channel inhibitor, nifedipine, markedly suppressed dopamine release from depolarized PC12 cells, suggesting that calcium entering through this channel was the predominant stimulus for dopamine efflux. Atrial natriuretic peptide maximally reduced depolarization-evoked dopamine release 20 +/- 3% at a concentration of 100 nM and this effect was abolished by nifedipine, but not by pretreatment with the N-type calcium channel inhibitor, omega-conotoxin, or an inhibitor of calcium-induced calcium release, ryanodine. In cells loaded with Fura-2, atrial natriuretic peptide both augmented depolarization-induced increases of intracellular free calcium concentrations and accelerated the depolarization-induced quenching of the Fura-2 signal by manganese, findings consistent with enhanced conductivity of calcium channels. Dopamine efflux induced by either the calcium ionophore, A23187, or staphylococcal alpha toxin was attenuated by atrial natriuretic peptide. Additionally, a natriuretic peptide interacting solely with the natriuretic peptide C receptor in these cells, C-type natriuretic peptide, also suppressed calcium-induced dopamine efflux in permeabilized cells. These data are consistent with natriuretic peptides attenuating catecholamine exocytosis in response to calcium but inconsistent with the neuromodulatory effect resulting from a reduction in intracellular calcium concentrations within pheochromocytoma cells.