Effect of aortic impedance on preload-afterload mismatch in canine hearts in situ

The aim was to examine the influence of the independent increase of aortic wall characteristics from vascular resistance on global left ventricular (LV) function in intact hearts. In 11 anesthetized dogs, aortic stiffness was increased by a constriction of the thoracic aorta using a stiff tube, and then, in nine dogs, total systemic resistance (TSR) was increased by an infusion of angiotensin II. During the above procedures, aortic input impedance and LV dimension were measured. Aortic input impedance spectra revealed the steady increase in the moduli at high frequencies by aortic constriction, indicating the increase in aortic stiffness. At the stage of increased aortic characteristic impedance (Zc) (134% of control) without a change in TSR, both LV end-diastolic diameter (LVEDD, 99%, p < 0.01 and stroke volume (SV, 95%, p < 0.01) decreased significantly without a change in LV end-systolic diameter (LVESD). During the increase in TSR produced by angiotensin II (128% of control) without a change in Zc, LVEDD tended to increase and LVESD significantly increased (103%, p < 0.01) associated with a decrease in SV (94%, p < 0.01). LV systolic mean wall stress was increased by angiotensin II (118%, p < 0.01), whereas it was unchanged by aortic constriction. In conclusion, the isolated increase in aortic stiffness without a change in TSR was associated with a reduction in LV preload and SV.

Early changes in the functions of cardiac sarcoplasmic reticulum in volume-overloaded cardiac hypertrophy in rats

By sequestering activator calcium, the sarcoplasmic reticulum (SR) plays the central role in the excitation-contraction (E-C) cycle of cardiac muscle. Hence, functional changes in the SR in diseased myocardium might critically determine its mechanical characteristics. Previously, we demonstrated that both Ca2+ release and uptake were increased in SR isolated from hearts showing compensatory left ventricular (LV) hypertrophy taken from pressure-overloaded rats. However, it has not been elucidated whether such alterations also occur in the volume-overloaded myocardium. Rats in which volume-overloaded hypertrophy had been induced by aortocaval shunt 12 weeks prior to the investigation were compared to sham-operated controls in terms of SR Ca2+ uptake and release, and density of Ca2+ releasing channels (ryanodine receptors, RyR). Isometric tension and intracellular Ca2+ transients were also measured using the bioluminescent Ca2+ indicator, aequorin, in isolated LV papillary muscles. The extent of hypertrophy was verified by measuring the ratio of biventricular weight to body weight. In vivo, the aortocaval shunt rats showed normal LV contractility and slightly depressed LV relaxation, indicating a compensatory (adaptive) stage of LV function. In contrast, Ca2+ release, uptake, and maximal number of [3H]-ryanodine binding sites were all significantly lower in aortocaval shunt rats than in controls. Both the Ca2+ transients and isometric relaxation of the isolated myocardium were significantly prolonged in aortocaval shunt rats, though their amplitudes were similar in the two groups. Thus, the volume-overloaded cardiac hypertrophy, even at its hemodynamically compensatory (adaptive) stage, (i) was accompanied by abnormal Ca2+ handling, as indicated by prolonged intracellular Ca2+ transients and isometric tension traces, (ii) seems to involve subcellular mechanisms related to decreases in SR Ca2+ release and uptake functions, as well as to a decrease in the number of RyR. Therefore, changes in the intracellular processes underlying cardiac E-C coupling, including SR function, precede the development of this type of heart disease.

[Influence of the dead space induced by the face mask on the measure of heart rate variability]

The respiratory pattern influences the power spectrum of heart rate variability and therefore control or monitoring of respiration is needed. The effect of the dead space induced by the face mask used in the expiratory gas exchange analysis on the measurement of heart rate variability was evaluated in 22 subjects (15 males and 7 females aged 39-76 years, mean 42 years) using electrocardiography recorded for 5 min during spontaneous respiration under the conditions of supine rest, sitting on the bicycle ergometer with and without a face mask. The power spectrum of heart rate variability was obtained by the coarse-graining spectral analysis (CGSA) method and the total power (TP : 0-0.5 Hz), low frequency component (LF: 0-0.15 Hz), high frequency component (HF: 0.15-0.50 Hz), HF/TP and LF/HF were measured. The volume of the face mask was 320 ml and the tidal volume during sitting with the face mask was 596 +/- 110 ml (444-808 ml). The value of LF/HF increased from supine rest to sitting in accordance to the change of body position (p < 0.05), but the value of LF/HF when sitting with the face mask decreased to the level during supine rest. The value of HF/TP decreased from supine rest to sitting (p < 0.05), but when sitting with the face mask returned to that during supine rest. To evaluate the effect of tidal volume, the subjects were divided into two groups (each of 11 subjects) by the median value of tidal volume (570 ml). The value of LF/HF decreased from supine rest to sitting with the face mask in the smaller tidal volume group (tidal volume < 570 ml) (p < 0.02). Moreover, there was a significant correlation between the change of the value of LF from supine rest to sitting with the face mask and the tidal volume (r = 0.44, p < 0.05). There results suggest that the power spectrum of heart rate variability is strongly influenced by the dead space induced by the face mask used in expiratory gas exchange analysis. In particular, the sympathetic activation from supine rest to sitting in subjects with the smaller tidal volume is unclear. Thus, interpretation of the results of heart rate variability with or without the face mask used in expiratory gas exchange analysis requires care.

Cytomegalovirus-associated myelodysplasia and thrombocytopenia in an immunocompetent adult

Myelodysplasia and severe thrombocytopenia in association with cytomegalovirus (CMV) infection in immunocompetent adults have rarely been reported. We describe a previously healthy man who developed severe thrombocytopenia with myelodysplastic changes of bone marrow and multiple autoimmune abnormalities following CMV infection. We also discuss possible mechanisms leading to myelodysplasia and thrombocytopenia in CMV infection. We believe that CMV infection should be considered in the differential diagnosis of myelodysplasia and acute thrombocytopenia.

Isolation of low density lipoprotein subfraction containing apolipoprotein B-like protein from Japanese eel Anguilla japonica plasma using dextran sulfate cellulose

Japanese eel (Anguilla japonica) possessed a unique lipoprotein profile in their plasma, reflecting high utilization of lipids. Low density lipoprotein (LDL) fraction isolated at the densities from 1.006 to 1.085 g/ml comprised the heterogeneous components with molecular weight (Mr) 1200 K, 470 K, and 250 K. LDL subfraction with Mr 1200 K was completely adsorbed to dextran sulfate cellulose (DSC) column which had been developed for LDL apheresis treatment of the patients with familial hypercholesterolemia, while LDL subfractions with Mr 470 K and 250 K had no affinity for the DSC column. LDL subfractions with Mr 470 K and 250 K were floated and settled, respectively, by centrifuging the unbound fraction of DSC column at a density of 1.063 g/ml. LDL subfraction with Mr 1200 K possessed apolipoprotein (apo) B-like protein of Mr 230 K, while apo A-I- and A-II-like proteins of Mr 25 K and 14 K were the main components in LDL subfractions with Mr 470 K and 250 K. The presence of apo B-like protein seemed to be responsible for the adsorption of LDL subfraction with Mr 1200 K for the DSC column. LDL subfractions with Mr 470 K and 250 K seemed to belong to high density lipoprotein (HDL) with respect to molecular weights and apolipoprotein features. To our knowledge, this is the first report of the separation of LDL and HDL from the plasma of Japanese eels using the DSC column.

Nitric oxide contributes to the progression of myocardial damage in experimental autoimmune myocarditis in rats

BACKGROUND

Excess amounts of NO produced by an inducible NO synthase (iNOS) in response to cytokines may be cytotoxic and can be destructive to tissue. We investigated the role of NO in the development of myocardial damage and the effects of aminoguanidine (AG), an inhibitor of iNOS, on experimental autoimmune myocarditis in rats.

METHODS AND RESULTS

Autoimmune myocarditis was induced in 20 Lewis rats by injection of porcine cardiac myosin. Ten of the 20 rats were administered AG. The severity of myocarditis was evaluated by measuring the size of myocarditic lesion and serum levels of CK-MB. Serum NO levels were determined using the Cd/Cu method. Tissue specimens were immunohistochemically examined for iNOS and nitrotyrosine. Histopathological study revealed extensive myocardial destruction and massive inflammatory cell infiltration in AG-untreated rats but only focal mononuclear cell infiltration in AG-treated rats. The mean percent areas of inflammatory lesions in the untreated and treated rats were 56 +/- 13% and 3 +/- 2%, respectively (P < .001). NO levels were 102 +/- 23 and 25 +/- 9 IU/L, respectively (P < .01). CK-MB levels were 68 +/- 13 and 16 +/- 13 nmol/L, respectively (P < .01). Superoxide production as measured with an ex vivo monitoring system was also significantly decreased in the treated rats. Nitrotyrosine relating to the generation of peroxynitrite was detected through immunostaining in the inflammatory lesions of untreated rats but not in those of treated rats.

CONCLUSIONS

Excess amounts of NO produced by iNOS appear to contribute to the progression of myocardial damage in myocarditis. AG may prove to be useful in the treatment of myocarditis.

Role of central ANG II receptors in stress-induced cardiovascular and hyperthermic responses in rats

The present study was carried out using a biotelemetry system to investigate whether central angiotensin II (ANG II) is involved in stress-induced cardiovascular and body temperature responses in rats. Intracerebroventricular injections of the nonselective ANG II-receptor antagonist saralasin and of the ANG II AT1-receptor antagonist losartan attenuated both the heart rate and pressor responses to immobilization stress in a dose-dependent manner. The elevation of plasma norepinephrine and epinephrine induced by immobilization stress was also suppressed by central ANG II-receptor blockade, suggesting a general attenuation of stress-induced sympathetic nervous and adrenomedullary activity by central ANG II-receptor blockade. The hyperthermia induced by immobilization stress was attenuated by central ANG II AT1-receptor blockade in a dose-dependent manner. The effects of central saralasin on the blood pressure response induced by immobilization stress were greater in Wistar-Kyoto rats than in spontaneously hypertensive rats. The present results suggest that central ANG II AT1-receptors are involved in expression of the tachycardia and hyperthermia, as well as the pressor response, induced by immobilization stress.

Influence of lateral head tilting on head-shaking nystagmus

We conducted a trial to determine whether or not head-shaking nystagmus (HSN) was influenced by lateral head tilting. Twenty-two patients with unilateral peripheral vestibular lesions were examined between July 1990 and June 1996. All of the patients were found to have horizontal HSN following horizontal head shaking in the upright head position. Eye movements were recorded by electronystagmography with the eyes open in complete darkness. Patients voluntarily tilted their heads to the lateral head positions with the assistance of the examiner as quickly as possible immediately after head shaking in the upright head position. Findings showed that monophasic horizontal HSN and the first phase of biphasic horizontal HSN were suppressed by lateral head tilting. The second phase of biphasic horizontal HSN was influenced differently by head tilting when compared with the first phase. Vertical (down-beating) components in horizontal HSN may appear in the peripheral vestibular lesions, but seem to have no definite relation to head positions.

Differences in sarcoplasmic reticulum gene expression in myocardium from patients undergoing cardiac surgery. Quantification of steady-state levels of messenger RNA using the reverse transcription-polymerase chain reaction

Little is known about any alterations in sarcoplasmic reticulum (SR) gene expression associated with cardiac diseases of varying degrees of severity. We assessed, using the reverse transcription-polymerase chain reaction (RT-PCR) technique, SR Ca2+ transport protein gene expression in small tissue samples from failing hearts in patients undergoing cardiac surgery. Total RNA was extracted from 30- to 50-mg samples from the hearts of 13 patients with coronary artery disease, congenital heart disease, or valvular heart disease. We used RT-PCR to synthesize and amplify cDNA encoding cardiac SR Ca(2+)-ATPase, ryanodine receptor (RYR), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The amount of each mRNA in the sample was expressed relative to the amount of GAPDH mRNA. The expression level of each mRNA was correlated with the cardiac functional index. The mRNA levels for Ca(2+)-ATPase and RYR varied between heart samples, but showed a positive correlation with left ventricular ejection fraction. Ca(2+)-ATPase mRNA levels showed in inverse relationship with plasma brain natriuretic peptide. In addition, we isolated partial cDNA encoding a human cardiac RYR. The cDNA consisted of 487 nucleotides, and the nucleotide and deduced amino acid sequences showed 93% and 99% homology, respectively, to those of rabbit cardiac RYR. These results suggest that decreased levels of mRNA for SR Ca2+ transport protein could be related to abnormal cardiac function, regardless of the etiology of the heart disease. RT-PCR provides a rapid and economical way of quantifying the expression of multiple genes in small specimens and may, therefore, aid understanding of the pathophysiology and treatment of heart disease.

Eradication of minimal residual disease during graft-versus-host reaction induced by abrupt discontinuation of immunosuppression following bone marrow transplantation in a patient with Ph1-ALL

We observed a patient in whom graft-versus-host disease (GVHD) appeared to induce a positive effect. This 32-year-old male with Philadelphia chromosome-positive acute lymphoblastic leukemia received a bone marrow transplant (BMT) from an HLA-identical sibling donor. We analyzed the bone marrow with the reverse transcriptase-polymerase chain reaction to screen for the minor bcr/abl transcript, which indicates the presence of minimal residual disease (MRD). MRD was present in the pre- and post-transplant phases. There was no evidence of acute GVHD by post-transplant day 45. We abruptly discontinued the immunosuppressive therapy in an attempt to eliminate MRD by inducing an antileukemic reaction during GVHD. GVHD associated with diarrhea and liver dysfunction developed on day 64. On day 105, MRD disappeared and GVHD was treated with prednisolone and cyclosporin. The disappearance of MRD may have been due to the graft-versus-leukemia (GVL) effect mediated by the alloimmune response of donor T lymphocytes. These findings suggest that induction of the GVL effect may be useful for eliminating MRD after BMT in leukemia patients at high risk of recurrence of the disease.

Altered cardiac mechanism and sarcoplasmic reticulum function in pressure overload-induced cardiac hypertrophy in rats

Cardiac sarcoplasmic reticulum (SR) sequesters Ca2+ and plays a crucial role in the regulation of intracellular Ca2+. Its functional properties are central to the excitation-contraction (E-C) cycle of cardiac muscle. In this study, we examined the hypothesis that alterations in SR function occur during the development of hypertrophy of the left ventricle (LV) induced in rats by pressure overload secondary to abdominal aortic coarctation. Ten days, 4 and 8 weeks after the operation, hemodynamic parameters were measured using a catheter-tip manometer. The SR vesicles of hypertrophic LV (group A) and sham-operated LV (group S) at each stage were used to study Ca2+ release and uptake, and to characterize the ryanodine receptor. Moderate hypertrophy was observed in group A even at the earliest stage. Systolic LV pressure and peak +dP/dt were significantly increased in group A. There were no significant change in diastolic LV pressure in either group at any stage. Hemodynamic data indicated that LV function in group A was enhanced during the development of the hypertrophy. The amount of Ca2+ release and uptake, and the number of ryanodine binding sites on the SR were higher in group A than in group S at both early and middle stages. However, 8 weeks after the operation, SR activity was normal, even though cardiac function was still augmented. Our results indicated that LV hypertrophy induced by pressure overload is associated with altered intracellular Ca2+ regulation, as reflected by the increased Ca2+ release and uptake functions of the SR and the quantitative change in the number of ryanodine receptors during the early stages of the development of hypertrophy. Therefore, alterations in the SR Ca2+ transport capacity could account, at least in part, for the alterations in E-C coupling seen in hypertrophy.

Autoimmune response in chronic ongoing myocarditis demonstrated by heterotopic cardiac transplantation in mice

BACKGROUND

Autoimmune mechanisms have been implicated in the pathogenesis of chronic ongoing myocarditis. To investigate this relation, we used an A/J mouse model inoculated with coxsackievirus B3 and determined whether myocarditis would be transferred to normal hearts that were heterotopically transplanted.

METHODS AND RESULTS

Inbred 3-week-old A/J mice were inoculated intraperitoneally with coxsackievirus B3 (Nancy strain; 2 x 10(4) plaque-forming units) and housed for > 60 days. The presence of the viral genome in the myocardium was determined by the polymerase chain reaction with primers specific for the 5' end of the coxsackievirus B3 genome performed at 40, 50, or 60 days after inoculation. Normal A/J mouse hearts were transplanted into the same strain of mice without myocarditis (group A) and into mice with chronic ongoing myocarditis (group B). The hearts were evaluated histologically 2 weeks after transplantation. Conventional histological examination of infiltrated T cells and macrophages was performed, and the expression of intercellular adhesion molecule-1, major histocompatibility complex (MHC) class I antigen, and MHC class II antigen was evaluated by immunoenzymatic staining. The concentrations of interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor (TNF-alpha) in the grafts were measured with an ELISA. The viral RNA genomes were not detected in the mice with chronic ongoing myocarditis, but their transplanted hearts did show myocarditis. In the hearts with induced myocarditis, infiltrated mononuclear cells consisted of CD4+ T cells, CD8+ T cells (CD4+ cell number > CD8+ cell number), and macrophages. Intercellular adhesion molecule-1, MHC class I antigen, and MHC class II antigen were expressed in the vascular endothelial cells and myocardial cells in and around the infiltrated lesions. The concentrations of IL-1 alpha and TNF-alpha in group B were significantly higher than those in group A (group A versus group B: IL-1 alpha, 125 +/- 35 versus 180 +/- 34 pg/mL; TNF-alpha, 45 +/- 15 versus 96 +/- 40 pg/mL; P < .05).

CONCLUSIONS

Results suggest that an autoimmune response may play a key role in the progression of chronic ongoing myocarditis.

Influence of aortic impedance on the development of pressure-overload left ventricular hypertrophy in rats

BACKGROUND

Aortic input impedance, which represents LV afterload, is considered to be a major determinant for the development of pressure-overload left ventricular (LV) hypertrophy.

METHODS AND RESULTS

To test whether the sustained change in aortic input impedance might affect the mode of development of LV hypertrophy, coarctation of either the ascending aorta (G1, n = 13) or suprarenal abdominal aorta (G2, n = 12) was performed over 4 weeks in 6-weeks-old Wistar rats. Although peak LV pressure and total systemic resistance were increased similarly in G1 and G2, time to peak LV pressure was decreased by 24% (P < .01) in G1 compared with G2. The aortic input impedance spectra revealed that the early systolic loading in G1 was characterized by an increase in characteristic impedance, whereas the late systolic loading in G2 was by an augmented arterial wave reflection. G1 showed a smaller increase (P < .01) in either the ratio of LV weight (mg) to body weight (g) or LV wall thickness than G2 after aortic banding. Myocyte diameter was also smaller (P < .05) in G1 (14.3 +/- 0.7 mm) than in G2 (16.1 +/- 1.2 mm). The ex vivo passive pressure-volume relation had a rightward shift in G1 compared with G2, suggesting less concentric LV hypertrophy in G1.

CONCLUSIONS

The sustained early systolic loading due to the increase in characteristic impedance was accompanied by less concentric, reduced hypertrophy, whereas the sustained late systolic loading due to the augmented arterial wave reflection was accompanied by concentric, adequate hypertrophy.

Interferon-gamma induces Ice gene expression and enhances cellular susceptibility to apoptosis in the U937 leukemia cell line

The roles of interferons (IFNs) in apoptosis are not fully understood. In this study we show that in the U937 monoblastic leukemia cell line, pretreatment with IFN-gamma enhanced sensitivity to apoptosis triggered by gamma-irradiation or antitumor agents (etoposide or adriamycin), as well as by anti-Fas antibody. In addition, IFN-gamma caused an increased expression of the interleukin-1 beta-converting enzyme (Ice) gene, following strong induction of the interferon regulatory factor-1 (IRF-1) gene, the product of which is a transcriptional activator of the Ice gene. An inhibitor of ICE/Ced-3 family proteases, Z-Asp-CH2-DCB, blocked apoptosis in control cells as well as in IFN-gamma-pretreated cells. These results suggest that enhanced susceptibility of IFN-gamma-pretreated cells to apoptosis is mediated through the induction of Ice by IRF-1. This pathway is not affected by interleukin-1 beta (IL-1 beta) since neutralizing antibody against IL-1 beta failed to suppress the IFN-gamma-mediated enhancement of cell death, and IL-1 beta itself did not mimic the effect of IFN-gamma.

A point mutation in glycoprotein IX coding sequence (Cys73 (TGT) to Tyr(TAT)) causes impaired surface expression of GPIb/IX/V complex in two families with Bernard-Soulier syndrome

Bernard-Soulier syndrome (BSS) is a rare inherited bleeding disorder which is caused by abnormal expression or function of the glycoprotein (GP) Ib/IX/V complex, a platelet major receptor for von Willebrand factor. We studied four BSS patients in two unrelated families in which the same and novel mutation was found. Flow cytometric analysis showed that GPIX was completely absent but residual amounts of GPIb alpha and GPV were detectable in these patients. We analyzed all coding regions of GPIb alpha, GPIb beta, GPV and GPIX which were amplified from the patients' genomic DNA by the polymerase chain reaction (PCR). In all four cases, we identified a point mutation in the GPIX coding region that changes the codon for cysteine 73 (TGT) to a codon for tyrosine (TAT). Furthermore, we confirmed by a transient expression study that the mutation caused the loss of adequate surface expression of GPIX. Since cysteine might be important for the secondary structure, this mutation of GPIX gene would lead to a dramatic conformational change of GPIX protein, resulting in the reduced surface expression. We concluded that this novel point mutation of the GPIX gene was responsible for BSS in these families.

A unique lipoprotein profile found in the plasma of cultured Japanese eelAnguilla japonica: very low density lipoprotein, but not high density lipoprotein, is the main component of plasma

A unique lipoprotein profile was found in the plasma of cultured Japanese eel,Anguilla japonica which accumulated more lipid in its muscle than in its liver. The plasma lipoprotein level of Japanese eels was in excess of 54 mg ml(1), a concentration considered to be hyperlipoproteinemic in relation to other teleosts. The plasma lipoproteins consisted of very low density lipoprotein (VLDL, density (d)<1.006 g ml(1)) low density lipoprotein (LDL, 1.006<d<1.085 g ml(1)), high density lipoprotein 2 (HDL2, 1.085<d<1.100 g ml(1)), and HDL3 (1.100<d<1.210 g ml(1)). VLDL, but not HDL, was the main component in the plasma of Japanese eels, unlike most teleosts where HDL is the main component. An additional lipoprotein, vitellogenin (1.210<d<1.280 g ml(1)), was induced by the injection of estradiol-17ß (E2), but VLDL was the main plasma component even in the E2-treated eels. VLDL was a triacylglycerol (TG)-rich lipoprotein and possessed two apolipoprotein (apo) B-like proteins of molecular weights (Mr) 260K and 230K as main components.LDL, HDL2, and HDL3 were revealed to consist of heterogeneous components by a density gradient ultracentrifugation. LDL was separated into three subclasses of LDL1 (1.030<d<1.038 g ml(1)), LDL2 (1.043<d<1.063 g ml(1)), and LDL3 (1.067<d<1.094 g ml(1)). LDL1 with apo B-like protein of Mr 230K was a TG-rich lipoprotein, while both LDL2 and LDL3 were cholesterol ester-rich lipoproteins with apo A-I-and A-II-like proteins of Mr 25K and 14K. The particle sizes of HDL2 and HDL3 subclasses differed, although all of HDL2 and HDL3 subclasses possessed apo A-I-and A-II-like proteins of Mr 25K and 14K as main components. To our knowledge, this is the first report of detailed plasma lipoprotein profile in Japanese eels.

A case of acute eosinophilic pneumonia. Evidence for hypersensitivity-like pulmonary reaction

We examined an 86-year-old man with acute respiratory failure. A chest roentgenogram showed diffuse reticular shadows. Transbronchial biopsy revealed thickening of the alveolar septa accompanied by moderate eosinophil infiltration. After admission to the hospital, the patient's symptoms immediately improved without any medication. Clinical course and pathologic findings suggested acute eosinophilic pneumonia caused by a hypersensitivity reaction.

hedgehog signaling independent of engrailed and wingless required for post-S1 neuroblast formation in Drosophila CNS

The hedgehog gene product, secreted from engrailed-expressing neuroectoderm, is required for the formation of post-S1 neuroblasts in rows 2, 5 and 6. The hedgehog protein functions not only as a paracrine but also as an autocrine factor and its transient action on the neuroectoderm 1–2 hours (at 18 degrees C) prior to neuroblast delamination is necessary and sufficient to form normal neuroblasts. In contrast to epidermal development, hedgehog expression required for neuroblast formation is regulated by neither engrailed nor wingless. hedgehog and wingless bestow composite positional cues on the neuroectodermal regions for S2-S4 neuroblasts at virtually the same time and, consequently, post-S1 neuroblasts in different rows can acquire different positional values along the anterior-posterior axis. The average number of proneural cells for each of three eagle-positive S4-S5 neuroblasts was found to be 5–9, the same for S1 NBs. As with wingless (Chu-LaGraff et al., Neuron 15, 1041–1051, 1995), huckebein expression in putative proneural regions for certain post-S1 neuroblasts is under the control of hedgehog. hedgehog and wingless are involved in separate, parallel pathways and loss of either is compensated for by the other in NB 7–3 formation. NBs 6–4 and 7–3, arising from the engrailed domain, were also found to be specified by the differential expression of two homeobox genes, gooseberry-distal and engrailed.

Natural killing activity in patients with spontaneous regression of malignant lymphoma

Previously, we proposed a new analysis of natural killing activity, for comparison, employing an "individual effector/target cell ratio" according to the number of effector cells in blood. The activity could be measured in four patients with spontaneous regression of malignant lymphoma. Despite the absence of episodes suggesting viral infections, patients with spontaneous regression had significantly higher activities prior to their regressions than either controls or patients without regression. In one patient who had a spontaneous regression accompanied by a high level of natural killing activity, subsequent exacerbation of the disease with a reduced activity was never followed by a regression and became life-threatening. In another patient, a spontaneous regression was accelerated after greater augmentation of natural killing activity was induced by a superimposed viral infection. These facts suggest that highly elevated natural killing activity may be one of the possible mechanisms responsible for spontaneous regression of malignant lymphoma.

A novel pre-B acute lymphoblastic leukemia cell line with chromosomal translocation between p16(INK4A)/p15(INK4B) tumor suppressor and immunoglobulin heavy chain genes: TGFbeta/IL-7 inhibitory signaling mechanism

p16 INK4A and/or p15 INK4B genes are frequently deleted in leukemias and other cancers. We have established a novel pre-B acute lymphoblastic leukemia (ALL) cell line (JKB2) with a chromosomal translocation between 9p2l and 14q32, on which p16INK4A/p15INK4B and heavy chain immunoglobulin (Ig) genes, respectively, are located. Homozygous deletions of P16INK4A/p15INK4B genes in JKB2 cells were confirmed by polymerase chain reaction, and their protein products were not detectable by Western blotting. Therefore JKB2 is the first example of an immunoglobulin heavy chain translocation associated with deletions of these genes. In JKB2 cells, cyclin-dependent kinase(CDK)4 and CDK6 formed complexes with cyclin D, due to the lack of p16, triggering phosphorylation of retinoblastoma protein (pRB) and continuous cell proliferation. Moreover, the growth of JKB2 cells was partially inhibited by TGF beta or IL-7, accompanied by decreased CDK4 and CDK6 expression, increased p2l and p27 expression, decreased p27 binding to CDK4/CDK6, and increased binding of p27 to CDK2. In addition, IL-7 both inhibited proliferation and induced differentiation of JKB2 cells. These studies suggest that a t(9;14)(p21;q32) chromosomal translocation can result in deletion of both p16 INK4A and p15 INK4B genes in pre-B ALL, and that the JKB2 cell line therefore provides a model for the study of leukemogenesis related to abnormalities in chromosome 9p2l. Moreover, they suggest that TGF-beta can, suppress JKB2 cell growth in a p15-independent mechanism.

Effect of right ventricular volume overload on left ventricular diastolic function in patients with atrial septal defect

This study was undertaken to investigate the effect of chronic right ventricular (RV) volume overload on left ventricular (LV) diastolic function. Twelve patients with atrial septal defect and 7 age-matched normal controls were examined. Patients with atrial septal defect were divided into 2 groups based on their Qp/Qs values (ASD1:Qp/Qs < or = 3, n = 7; ASD2:Qp/Qs > 3, n = 5). The LV volume curve and its first derivative were derived by a frame-by-frame analysis of the left ventriculogram. The peak filling rate was defined by the peak positive first derivative of the LV volume curve. We measured the time constant, isovolumetric relaxation time, stiffness constant and compliance at LV end-diastole. The time constant was significantly prolonged in the ASD2 group compared with the controls, and the isovolumetric relaxation time in both atrial septal defect groups was also prolonged compared with the controls. The peak filling rate, which was normalized by end-diastolic volume, was lower in the ASD2 group than in the controls. Although the stiffness constant and the compliance at LV end-diastole in the controls were not significantly different from those in the atrial septal defect group, an upward and leftward displacement of the left ventricular pressure-volume curve was observed in patients with atrial septal defect. Moreover, a significant correlation (r = 0.78, p < 0.01) was observed between the time constant and RV end-diastolic pressure. Thus, these results suggest that chronic RV volume overload affects left ventricular diastolic function.