The significance of cytomegalovirus infection over the clinical course of adult T-cell leukemia/lymphoma

The significance of cytomegalovirus (CMV) infections developed over the clinical course of adult T-cell leukemia/lymphoma (ATLL) were evaluated in relation to the patient survival rate, ATL activity and immunocompetent cells. ATLL patients with CMV infections on admission exhibited a poor survival rate, while patients with CMV infections at any time after admission survived longer than those not infected with this virus. ATLL patients who exhibited a numbers of CMV infection on admission showed higher ATL activity and had lower numbers of CD8-positive and CD56-positive cells than those who developed CMV infections at any time after admission. Therefore, it appears likely that patients with CMV infections on admission were in an immunosuppressive state due to aggressive ATL activity.

Cytomegalovirus infection is not necessarily a poor prognostic factor in adult T-cell leukemia/lymphoma

The relationship between cytomegalovirus (CMV) antigenemia and the clinical course was examined in 57 patients with adult T-cell leukemia/lymphoma (ATLL). All patients included had the acute/lymphoma type of ATL according to the criteria of the Japan Lymphoma Study Group (LSG). CMV antigenemia was assessed on admission and at the time when the patients had fever higher than 37. 5 degrees C, which did not respond to antibiotics for longer than 3 days. The incidence of CMV antigenemia was 44%. Approximately 90% of patients with CMV antigenemia died of infections with viruses, bacteria, and/or fungi, while approximately 40% of patients without CMV antigenemia died of deterioration of ATLL (P<0.0001). In this study, the patients with CMV antigenemia tended to survive longer than those negative for it (321.4 days vs. 266.2 days), although there was no statistical significance (P=0.09). Kaplan-Meier analysis revealed that CMV antigenemia was not a poor prognostic factor. When the disease status of ATLL was evaluated by thymidine kinase (TK) and soluble interleukin 2 receptor (sIL-2R), both had lower titers during CMV antigenemia (TK: P=0.01, sIL-2R: P=0.03, respectively). Therefore, CMV infections in ATLL patients seemed to have bimodal meanings; CMV infection at the end of clinical course were life-threatening, but infection during the first half of clinical course seemed to suppress ATLL activity and to contribute to the longer survival of the patients.

[Syndrome of inappropriate antidiuretic hormone secretion associated with meningeal infiltration of tumor cells and elevated interleukin-1 beta and interleukin-6 in cerebrospinal fluid of a patient with adult T-cell leukemia]

A 73-year-old man with acute adult T-cell leukemia (ATL) in remission was re-admitted to our hospital due to drowsiness, headache, and bilateral knee joint pain on May 17, 1998. On admission, examinations revealed decreased serum sodium concentration (112 mEq/l), low plasma osmotic pressure (259 mOsm/l), and elevated antidiuretic hormone(5.6 pg/ml). Cerebrospinal fluid examination showed an increased number of abnormal flower-like lymphocyte (951/microliter). Brain computed tomography and magnetic resonance imaging found no abnormality in the hypothalamus or pituitary gland. These findings yielded a diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH). Though ATL patients typically exhibit a variety of clinical symptoms, SIADH is rarely one of the complications. Further investigation showed that IL-1 beta and IL-6 concentrations were increased in spinal fluid but not in serum. Recently, it has been reported that exogeneous IL-6 is an inducer of ADH secretion, and that primary ATL cells and HTLV-I infected cell lines can produce IL-6. In this case, we speculated that IL-6 produced by ATL cells that infiltrated a cerebral lesion may have played an important role in the development of SIADH.

Possible involvement of tyrosine kinase activation in lipopolysaccharide-induced expression of Ca(2+)-insensitive but calmodulin-coupling nitric oxide synthase in rat glial cells

To clarify the properties of an inducible type of nitric oxide synthase (i-NOS) in the brain, we examined whether lipopolysaccharide (LPS) induces NOS in glial cells cultured from neonatal rats. NOS activities (NO2- accumulation and L-[14C]citrulline formation) were detected by treatment with LPS at 10 micrograms/ml for 6-72 hr. L-[14C]citrulline formation by LPS-induced i-NOS was inhibited by NG-monomethyl-L-arginine (a NOS inhibitor) and diphenyleneiodonium (a flavo-protein inhibitor). The activity was not markedly changed in the presence or absence of Ca2+. The induction of i-NOS by LPS was abolished by cycloheximide, actinomycin D, or dexamethasone. In addition, the induction was inhibited by herbimycin A (a tyrosine kinase inhibitor), but was not by staurosporine, W-7, or FK-506. After LPS stimulation, 130 kDa proteins were reacted with anti-rat liver i-NOS antibody 5-72 hr. i-NOS induced from glial cells coupled tightly with endogenous calmodulin (CaM) even in the absence of Ca2+. These results suggest that LPS induces expression of 130-kDa i-NOS through an activation of tyrosine kinase, after which i-NOS couples with CaM, and that NO is formed for 6-72 hr in glial cells.

Studies on the activation mechanisms of guanylyl cyclase by serotonin, probably through a novel subtype of serotonin receptor (5-HTGC)

Characterization of the serotonin-induced increase in guanosine 3',5'-cyclic monophosphate (cyclic GMP) was investigated and compared with that induced by atrial natriuretic peptide (ANP) in NG108-15 cells. The cyclic GMP formed by serotonin or ANP was transported in a similar manner to the extracellular medium, although the cyclic GMP formed by bradykinin was not. Serotonin and ANP raised cyclic GMP additively. Serotonin-induced cyclic GMP formation was completely inhibited by pretreatment with 100 nM 12-o-tetradecanoylphorbol 13-acetate (TPA), although that induced by ANP was only partially inhibited and the effects were blocked by pretreatment with staurosporin. In membrane preparations, ANP stimulated cyclic GMP formation in the presence of ATP, but serotonin did not. Serotonin-stimulated cyclic GMP formation was found to occur in neuroblastoma N18TG-2, but not in glioma C6Bu-1. These results suggest that a novel subtype of serotonin receptors (5-HTGC) which stimulates membrane-bound guanylyl cyclase, different from that stimulated by natriuretic peptide, may exist especially in neurons.

Inhibition of constitutive nitric oxide synthase in the brain by pentamidine, a calmodulin antagonist

Nitric oxide (NO) which is produced by activation of Ca2+/calmodulin-dependent NO synthase is known to induce neuronal damage. We examined the effects of 3'-azido-2',3'-dideoxythymidine (AZT, a reverse transcriptase inhibitor), pentamidine (a therapeutic drug for Pneumocystis carinii pneumonia) and calmodulin antagonists such as trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) on NO synthase activation. Although AZT had no effect on the activity of constitutive neuronal NO synthase, pentamidine inhibited the activation of neuronal NO synthase as did trifluoperazine and W-7. The inhibition by pentamidine was prevented by the addition of purified calmodulin. In addition, pentamidine inhibited calmodulin-dependent activation of neuronal NO synthase purified from rat cerebellum. From these results, it is suggested that pentamidine inhibits the neuronal NO synthase activation by probably acting as a calmodulin antagonist.

Escherichia coli is able to grow with negligible sodium ion extrusion activity at alkaline pH

The Escherichia coli mutant NM81, which is deficient in the nhaA gene for the sodium/proton antiporter, still has a sodium ion extrusion activity because of a second antiporter encoded by nhaB (E. Padan, N. Maisler, D. Taglicht, R. Karpel, and S. Schuldiner, J. Biol. Chem. 264:20297-20302, 1989). By chance, we have found that E. coli pop6810 already contains a mutation affecting the sodium ion circulation, probably in or near nhaB, and that its delta nhaA mutant, designated RS1, has no sodium ion extrusion activity at alkaline pH. The growth of RS1 was inhibited completely by 0.1 M sodium, whereas growth inhibition of NM81 was observed only at sodium concentrations greater than 0.2 M. RS1 grew at a normal rate in an alkaline medium containing a low sodium concentration. Furthermore, RS1 grew with a negligible proton motive force in the alkaline medium containing carbonyl cyanide m-chlorophenylhydrazone. The transport activities for proline and serine were not impaired in RS1, suggesting that these transport systems could be driven by the proton motive force at alkaline pH. These findings led us to conclude that the operation of the sodium/proton antiporter is not essential for growth at alkaline pH but that the antiporter is required for maintaining a low internal sodium concentration when the growth medium contains a high concentration of these ions.