Four years follow-up study in patients with Takayasu arteritis and severe aortic regurgitation; assessment by echocardiography

We prospectively performed the follow-up study in 11 female patients with Takayasu arteritis and severe aortic regurgitation by echocardiography. A mean follow-up period was 4 years. The inflammatory state was controlled in all patients. Antihypertensive agents including beta-blocker were administered in nine patients. Heart failure did not progress in all patients except one. No candidate for cardiac surgery appeared during the follow-up period. Aortic root diameter, left atrial, left ventricular end-diastolic and end-systolic dimensions, wall thickness, left ventricular mass, and percent fractional shortening of the left ventricle showed no significant change in echocardiography. These data indicate that left ventricular disturbance might be slowly progressive in patients with Takayasu arteritis and severe aortic regurgitation. Systemic hypertension and the inflammatory state should be well controlled in managing the patients. beta-blocker might be useful in some patients with Takayasu arteritis and severe aortic regurgitation. Further follow-up is necessary for the decision of the cardiac surgical indication.

An aggressive nasal lymphoma accompanied by high levels of soluble Fas ligand

Fas ligand (FasL), either in the membrane bound form or soluble form, has cytotoxic activity against Fas-expressing cells. We report a case of nasal lymphoma accompanied by liver damage and pancytopenia. The serum level of soluble FasL (sFasL) was very high on admission, but rapidly decreased to normal levels after chemotherapy for lymphoma. Liver damage and pancytopenia also improved with the decrease in serum sFasL. Since Fas is expressed on both hepatocytes and haemopoietic cells, these facts suggest that FasL was expressed on lymphoma cells and directly associated with pathogenesis of liver damage and pancytopenia through its cytotoxic activity.

"Mass-forming" pancreatitis masquerades as pancreatic carcinoma

CONCLUSION

When a patient with a hypervascular pancreatic mass has a history of alcoholism and pancreatitis, and normal serum levels of CA 19-9, mass-forming pancreatitis should be kept in mind as a differential diagnosis of pancreatic carcinoma.

BACKGROUND

Chronic and/or acute pancreatitis sometimes produces a pancreatic mass; and differentiation from pancreatic carcinoma is of clinical importance.

METHODS

A total of 13 Japanese patients with mass-forming pancreatitis were retrospectively reviewed in order to clarify clinical features which can differentiate between mass-forming pancreatitis and pancreatic carcinoma.

RESULTS

Six of the 13 patients had a history of chronic pancreatitis or acute pancreatitis from 8 mo to 11 yr previously. Eleven patients were alcoholic. Serum carcinoembryonic antigen and carbohydrate antigen 19-9 levels were within normal limit in 9 of 12 patients examined and in all 12 patients examined, respectively. The pancreatic mass was located in the head of the pancreas in 9 patients, in the body in 1 and in the tail in 3. The mean greatest diameter of the mass was 2.8 cm. Six of the 13 pancreatic masses were hypoechoic by ultrasonography. Ten of the 13 pancreatic masses were of low-density by computed tomography. Two of the five masses examined were hypervascular at arterial and/or venous phase by angiography. Significant factors differentiating from pancreatic carcinoma were age, alcoholism, history of pancreatitis, serum levels of CA 19-9 and hypervascularity. Follow-up ultrasonography and/or computed tomography showed diminution of the mass in 1 to 2 mo in four patients, together with decrease of serum carcinoembryonic antigen and/or carbohydrate antigen 19-9 levels in two of the four patients.

Inferior vena caval thrombus associated with double neoplasms of the retroperitoneum and kidney: report of a case

We report herein the case of a patient we recently encountered who was found to have a giant retroperitoneal tumor coincident with tumor thrombus in the inferior vena cava (IVC). On the assumption that the origin was retroperitoneal, the two lesions were resected using an intracaval filter. However, histopathological examination of the specimens revealed neurilemoma for the retroperitoneal tumor and adenocarcinoma for the tumor thrombus. A right renal tumor was subsequently detected, which led to right nephrectomy being performed en bloc with part of the IVC using a venoarterial bypass. Microscopy revealed carcinoma of the Bellini duct, or collecting duct, which is an extremely rare tumor. Retrospectively, a lesion with soft tissue density was noted in the renal vein. Surgical management focused on the prevention of pulmonary embolism. We describe this case because of its extreme rarity and its significance from the viewpoint of diagnosis and therapeutic strategies.

Activation of RAC-protein kinase by heat shock and hyperosmolarity stress through a pathway independent of phosphatidylinositol 3-kinase

RAC protein kinase (RAC-PK), a serine/threonine protein kinase containing a pleckstrin homology (PH) domain, was activated by cellular stress such as heat shock and hyperosmolarity. Wortmannin, which is known as a potent inhibitor of phosphatidylinositol 3-kinase and normally inhibits growth factor-induced activation of RAC-PK, did not suppress heat-shock induced activation of RAC-PK, indicating that this stress-induced activation of the kinase is not mediated by phosphatidylinositol 3-kinase. The PH domain was indispensable for stress-induced activation of RAC PK. In heat-treated cells, PKC delta, a member of the protein kinase C family, was found to associate with the PH domain of RAC-PK. This PKC subspecies was phosphorylated in vitro by RAC-PK. The results suggest that RAC-PK may play a role in the cellular response to stress through its PH domain.

Swapping between Fas and granulocyte colony-stimulating factor receptor

Fas belongs to the tumor necrosis factor/nerve growth factor receptor family. The Fas ligand binds to its receptor, Fas, and induces apoptosis in Fas-bearing cells. The granulocyte colony-stimulating factor receptor (G-CSFR) is a member of the hemopoietic growth factor receptor family. G-CSF induces its dimerization and regulates the proliferation and differentiation of neutrophilic granulocytes. We constructed hybrid receptors between Fas and G-CSFR and expressed them in the mouse T cell line WR19L or the mouse myeloid interleukin-3-dependent FDC-P1 cell line. The Fas ligand or an agonistic anti-Fas antibody stimulated proliferation of the FDC-P1 transformants expressing a chimera consisting of the Fas extracellular and G-CSFR cytoplasmic regions. On the other hand, G-CSF could not induce apoptosis in the transformants expressing the chimera consisting of the G-CSFR extracellular and Fas cytoplasmic regions, but these cells were killed by a polyclonal antibody against G-CSFR. These results indicated that receptors belonging to different receptor families can be functionally exchanged and confirm that a homodimer of G-CSFR can transduce the growth signal, whereas Fas must be oligomerized (probably trimerized) to transduce the apoptotic signal.

Interactions between insulin-like growth factor-I (IGF-I) and the renin-angiotensin system in follicular growth and ovulation

The interactions between insulin-like growth factor-I (IGF-I) and the renin-angiotensin system (RAS) in follicular growth and ovulation were studied with the use of an isolated perfused rabbit ovary preparation. Ovulation failed to occur in either control ovaries or the experimental ovaries perfused with IGF-I in a concentration of 1, 10, or 100 ng/ml in the absence of gonadotropin. Exposure to IGF-I stimulated the secretion rate of angiotensin II-like immunoreactivity (Ang II-IR) in perfused rabbit ovaries in a dose-dependent manner. The percent increase in follicle diameter in ovaries perfused with IGF-I for 12 h was significantly correlated with the secretion rate of Ang II-IR at 12 h after exposure to IGF-I. The addition of IGFBP-3 to the perfusate did not induce ovulation in the absence of gonadotropin, but exposure to IGFBP-3 inhibited hCG-induced ovulation in a dose-dependent manner. In addition, IGFBP-3 significantly reduced the ovarian secretion rate of Ang II-IR and prostaglandins stimulated by hCG administration. Intrafollicular plasminogen activator (PA) activity significantly increased within 4 h after exposure to 100 ng/ml of IGF-I, compared with that in control ovaries perfused with medium alone. The concomitant addition of IGFBP-3 to the perfusate significantly reduced the IGF-I-stimulated PA activity in the preovulatory follicles at 4, 6, and 8 h after exposure to IGF-I. However, IGFBP-3 alone affected neither the ovarian secretion rate of Ang II-IR nor intrafollicular PA activity. Exposure to streptokinase, an exogenous PA, in vitro stimulated both follicular growth and the intrafollicular Ang II-IR content. In conclusion, IGF-I enhances both ovarian Ang II production and follicular development by stimulating intrafollicular PA activity.

The dual expression of minor and major bcr/abl chimeric mRNA in blast crisis of chronic myelogenous leukemia

The hypothesis that minor bcr/abl fusion mRNA is produced in blast crisis of chronic myelogenous leukemia (CML) is examined. The RNA transcripts encoding the minor and major bcr/abl fused protein were detected by polymerase chain reaction (PCR) using RNA from peripheral blood or bone marrow cells of eight patients with blast crisis or accelerated phase of CML. The mRNA encoding for major bcr/abl was detected in all eight cases. In four patients, however, transcripts encoding for minor bcr/abl mRNA were detected, as well as major bcr/abl mRNA. The presence of minor bcr/abl mRNA was verified with the hybridization with a junction-specific probe and DNA sequencing analysis of PCR products. The appearance of minor bcr/abl fusion mRNA was associated with the lymphoblastic immunophenotype of the blast cells. In two of these four patients, samples of initial diagnosis of chronic phase of CML were available, which did not show minor bcr/abl transcript. We conclude that the appearance of minor bcr/abl mRNA transcript is associated with the terminal evolution of CML in lymphoblastic crisis.

[Noninvasive regional cerebral blood flow measurements at pre- and post-acetazolamide test using 99mTc-ECD]

A technique for serial noninvasive cerebral blood flow measurements at pre- and post-acetazolamide (Diamox) test was newly developed using 99mTc-ECD without blood sampling. Baseline mean cerebral blood flow (mCBF) was measured from graphical analysis of time activity curves for brain and aortic arch obtained from radionuclide angiography by injection of 370-555 MBq 99mTc-ECD. The first SPECT study was performed immediately after intravenous administration of 1 g of Diamox, then baseline regional cerebral blood flow (rCBF) was calculated using Lassen's correction algorithm. Immediately after the stop of the first SPECT study, additional 555-740 MBq of 99mTc-ECD was administered, thereafter the second SPECT study was started. Post-Diamox SPECT images were obtained by subtraction of the first baseline images from the second images. Using Lassen's algorithm, post-Diamox mCBF was estimated from the baseline mCBF, the baseline mean SPECT counts, and post-Diamox mean SPECT counts corrected for administered dose and imaging time. Post-Diamox rCBF was obtained from the post-Diamox mCBF and the post-Diamox mean SPECT counts using Lassen's algorithm. Coefficient variation was shown 2.7% and 3.5%: mCBF and rCBF, respectively in test-retest results in six patients without Diamox administration. Nine demented patients without vascular disorders showed significant mCBF increase of 35.7% on the average by post-Diamox. In conclusion, this simplified method is practically useful for measuring CBF at pre- and post-Diamox test within short period of time without any blood sample.

Nitrergic innervation of the rat larynx measured by nitric oxide synthase immunohistochemistry and NADPH-diaphorase histochemistry

We evaluated the involvement of nitric oxide (NO) in the laryngeal innervation of rats using NADPH-diaphorase (NADPH-d) histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry. The findings obtained by NADPH-d histochemistry were identical with those obtained by nNOS immunohistochemistry, indicating that NADPH-d is nNOS in the laryngeal innervation system. We found NADPH-d-positive nerve fibers in every region of the larynx. In the epithelia of the mucosa, a small number of NADPH-d-positive nerve fibers were detected. The plexus of NADPH-d-positive nerve fibers was commonly found in the lamina propria, and some of these fibers were clearly associated with blood vessels. We also noted NADPH-d-positive nerve fibers in the region of laryngeal glands. Some of these fibers appeared to terminate in the glandular cells. We found NADPH-d-positive nerve fibers with varicosities in the intrinsic laryngeal muscle and free-ending nerve fibers on the muscle fiber. Motor end plate-like structures were positive for NADPH-d histochemistry. The NADPH-d-positive nerve fibers appeared to terminate at motor end plate-like structures in two of nine rats examined. A cluster of NADPH-d-positive neurons were occasionally present in the lamina propria of the laryngeal mucosa, in the connective tissue between the thyroid cartilage and intrinsic laryngeal muscle, and in the connective tissue near the cricoarytenoid joint. The present findings suggest that NO participates in the autonomic, sensory, and motor innervation of the larynx.

An antisense oligodeoxynucleotide to glyceraldehyde-3-phosphate dehydrogenase blocks age-induced apoptosis of mature cerebrocortical neurons in culture

We recently reported that the age-induced apoptotic death of cultured cerebellar neurons is correlated with an increased expression of a particulate-bound 38-kDa protein that we identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). To determine whether this phenomenon of GAPDH overexpression occurs in other cell types, we selected primary cultures of cerebrocortical cells for testing, because under normal culture conditions, cortical neurons die progressively after 15 days in vitro. As with cerebellar neurons, this age-induced neuronal death involves ultrastructural changes and internucleosomal DNA fragmentation characteristic of apoptosis and is effectively prevented by actinomycin-D and cycloheximide. Moreover, a GAPDH antisense oligodeoxyribonucleotide arrested this cortical neuronal death for about 4 to 5 days and thus was more effective than cycloheximide. By contrast, its corresponding sense oligonucleotide had no effect. Additionally, the age-induced apoptosis of cortical neuronal cultures is effectively protected by aurintricarboxylic acid and tetrahy-droaminoacridine (an antidementia drug). Before cell death, GAPDH mRNA levels increased by about 2-fold and the increase was blocked by the above-mentioned neuroprotective agents and the GAPDH antisense, but not sense, oligonucleotide. The effects of antisense oligonucleotide are more robust in the present case than those found with cerebellar neurons, and they indicate a significant, though at present not defined, role of GAPDH in the apoptotic process occurring in these two types of neurons.

Urinary albumin excretion in short children treated with recombinant human growth hormone

The urinary levels of albumin, beta 2-microglobulin (BMG) and beta-D-N-acetyl glucosaminidase (NAG) were studied in 30 children with short stature due to partial or complete growth hormone (GH) deficiency under treatment. All 30 children had a normal urinalysis and no clinical evidence of renal disease. They were treated with recombinant GH in a dose of 0.5 IU/kg/week given subcutaneously. The mean albumin excretion rate (9.13 +/- 8.33 micrograms/min/1.73 m2) of these children was significantly higher than that (4.2 +/- 2.27 micrograms/min/1.73 m2) of 30 age-, sex- and pubertal status-matched normal children (p < 0.01). BMG and NAG excretion was normal in both groups. There was no correlation between the urinary albumin excretion rate and the duration of GH treatment. Among the GH-treated children, the urinary albumin excretion rate was correlated significantly with circulatory insulin-like growth factor I (IGF-I) (r = 0.65, p < 0.01). In 7 other children analyzed before and three months after start of GH treatment, the mean urinary albumin excretion rate increased significantly from 4.71 +/- 3.95 micrograms/min/1.73 m2 to 8.29 +/- 2.70 micrograms/min/1.73 m2 (p < 0.03). These results suggest the possibility of functional glomerular alterations during GH therapy.

Superoxide dismutase activity in human glomerulonephritis

Superoxide dismutase (SOD) in renal tissue biopsy specimens obtained from patients with immunoglobulin A nephropathy (13 cases) and non-immunoglobulin A mesangial proliferative glomerulonephritis (nine cases) was studied at the protein level by an enzyme-linked immunosorbent assay method and at the mRNA level by the reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Total SOD activity in the tissue supernatant was measured by applying an electron paramagnetic resonance/spin trapping method. Normal renal tissues obtained from kidneys removed for malignancies (six cases) were included as healthy controls. The copper and zinc form of SOD (Cu,Zn-SOD) activity at both the protein and mRNA levels was lower in the moderately or severely damaged tissues compared with that in the normal or mildly damaged tissues. On the other hand, manganese SOD (Mn-SOD) values at either the protein level or the mRNA level did not differ significantly between control and patient samples. In the histochemical study using a polyclonal rabbit anti-Cu,Zn-SOD antibody, the staining intensity for Cu,Zn-SOD antigen was lower in the areas with advanced histologic damage than in the intact tissues. A follow-up study showed that renal function deterioration was proportionately slower in patients whose SOD activity was within the range of healthy tissue levels at the time of biopsy. Our data suggest that a lower level of SOD activity, whether as a cause or a consequence of the disease process, might induce a decrease in the scavenger reaction of superoxide (O2-) thus causing the tissue to become more vulnerable to oxidative stress.

[Anesthesia for a patient with severe aplastic anemia]

A 48-year-old female with severe aplastic anemia was scheduled for transurethral lithotomy because of pyelonephritis and urethral stone. Laboratory studies showed anemia (168 x 10(4).mm-3), leukopenia (2300.mm-3) and thrombocytopenia (5000.mm-3). Bleeding time exceeded 30 min, but the transfusion of fresh platelet concentrate was not effective for bleeding tendency. Anesthesia was induced with midazolam 0.5 mg and fentanyl 100 micrograms, and maintained with N2O-O2-sevoflurane through a mask. The operation, which lasted for 40 min, was uneventful without marked hemodynamic changes, bucking or massive bleeding. Although 100 units of fresh platelet and 13 units of leucocyte poor red cells were infused during hospitalization, macrohematuria continued for about 3 weeks after this operation.

Morphological observations of megakaryocytic emperipolesis in the bone marrow of rats treated with lipopolysaccharide

A morphological examination was performed on megakaryocytic emperipolesis containing neutrophils in the rat bone marrow induced by intravenous administration of lipopolysaccharide (LPS). Ultrastructurally, the engulfed neutrophils appeared to lie in the demarcation membrane system (DMS) of megakaryocytes. Intact neutrophils generally migrated from DMS into the lumen of vascular sinus across the endothelium of sinus wall. However, some neutrophils showed characteristics of apoptosis, and DNA fragmentation was detected in these cells by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling method. Thus, the cell death of neutrophils engulfed by megakaryocytes was thought to be apoptosis. The present results suggest that megakaryocytes contribute to random selection of an excess of neutrophils in the bone marrow of rats treated with LPS.

A serological survey of turkey rhinotracheitis virus infection in chickens in Japan

A total of 4,111 chicken sera collected from 1985 to 1995 at 137 farms in 36 prefectures were subjected to an enzyme-linked immunosorbent assay (ELISA) to test for antibodies against turkey rhinotracheitis (TRT) virus. The antibodies to TRT virus were detected in the chicken sera collected from 1988 to 1995, but the antibodies to TRT virus were undetectable in the sera of chickens collected before 1987. The antibody positive rates each year ranged from 2.2% (1988) to 54.2% (1995). Recently, the TRT virus has spread over the flocks of commercial broiler and layer chicken throughout the country. The serological findings indicated that the TRT virus had invaded the chickens before 1988, and has been widespread thereafter in Japan.

Induction of antinuclear antibody after interferon therapy in patients with type-C chronic hepatitis: its relation to the efficacy of therapy

BACKGROUND

The prevalence of antinuclear antibody (ANA) and interferon (IFN)-induced ANA has been documented in patients with chronic hepatitis C. In the present study we evaluated whether the induction pattern of ANA after IFN therapy is related to the efficacy of IFN therapy.

METHODS

Forty-four patients with chronic hepatitis C were enrolled. Autoimmune hepatitis was excluded in all. ANA was measured every month before, during, and for 6 months after IFN therapy (total dose, 336-480 M units).

RESULTS

Eight of the 44 (18%) patients were positive for ANA before IFN therapy (group I). In group I six of the eight ANA-positive patients showed an increase in ANA titers during the therapy. Twenty-two of 36 (61%) ANA-negative patients turned positive for ANA, with titers of 1:80 or less during IFN therapy (group II). In 14 of the 36 (39%) ANA-negative patients ANA remained negative throughout the therapy (group III). The rates of sustained responders with a negativity of serum hepatitis C virus RNA and with normal alanine aminotransferase levels for at least 6 months after the cessation of therapy in groups I, II, and III were 25%, 23%, and 21%, respectively, giving no significant difference in the efficacy of therapy. No serious side effect was observed during the therapy.

CONCLUSIONS

Administration of IFN frequently produced an induction of ANA or an increase in its titer, which did not affect the efficacy of IFN therapy.

Functional contribution of preoperative portal vein occlusion to hepatectomy. With special reference to hepatic energy charge and DNA synthesis after hepatectomy in rats

OBJECTIVE

To examine possible functional contributions of preoperative portal branch ligation before hepatectomy (PBL-Hx).

DESIGN

Rats were randomly divided into 3 groups. In the PBL-Hx group, the portal branch supplying the left lateral and median lobes of the liver was ligated and the corresponding lobes (48% of the whole liver) were excised 2 days later. In the sham groups (one 68% Hx; the other 47% [hereafter, sham-67% Hx, and sham-47% Hx]), originally ligated lobes and left lateral and caudate lobes, similar to the excised liver volume in the PBL-Hx group, respectively, were excised 2 days after sham operation without PBL.

MAIN OUTCOME MEASURES

Hepatic adenine nucleotides and energy charge, which are essential for vital function of hepatocytes, and liver regeneration were assessed by the DNA synthesis rate and weight before Hx and on days 1, 2, 3, and 7 after Hx.

RESULTS

The remaining liver weight was restored similarly in the PBL-Hx and sham-47% Hx groups and more rapidly than in the sham-68% Hx group. Further enhancement of DNA synthesis did not occur after Hx in the PBL-Hx group, and hepatic energy charge did not decrease. In contrast, hepatic DNA synthesis was significantly activated depending on the excised liver volume in both the sham-Hx groups and was accompanied by corresponding decreases in hepatic energy charge.

CONCLUSION

Preoperative PBL has a functional advantage because the recovery of the remaining liver volume is not impaired and hepatic energy charge is preserved with no further enhancement of DNA synthesis after Hx.

Effects of insulin-like growth factor-I on follicle growth, oocyte maturation, and ovarian steroidogenesis and plasminogen activator activity in the rabbit

We examined the effects of insulin-like growth factor (IGF)-I on follicular growth, oocyte maturation, and ovarian steroidogenesis and plasminogen activator (PA) activity in vitro, using a perfused rabbit ovary preparation in order to determine whether the follicle-stimulating effects of growth hormone (GH) are mediated by IGF-I. The addition of IGF-I to the perfusate stimulated follicular growth and the resumption of meiosis in follicular oocytes in a dose-dependent manner. There was no significant difference in the production of progesterone by perfused rabbit ovaries between IGF-I-treated and control ovaries, whereas IGF-I increased the production of estradiol (E2) by perfused rabbit ovaries in a dose-dependent manner. The concomitant addition of a monoclonal antibody recognizing the type I IGF receptor, alpha IR-3, to the perfusate significantly blocked IGF-I-stimulated follicular growth, oocyte maturation, and E2 production. Intrafollicular PA activity increased significantly 4 h after exposure to 10 or 100 ng/ml of IGF-I and reached maximal levels at 6 h. The percentage increase in follicle diameter at 6 h after exposure to IGF-I was significantly correlated with the intrafollicular PA activity. Treatment with GH resulted in a 2.7-fold increase in intrafollicular levels of IGF-I mRNA. The binding of [125I]-IGF-I to rabbit ovarian membrane preparations was inhibited by unlabeled IGF-I and IGF-II in a concentration-dependent manner. The relative affinity of the IGF-I receptor for IGF-I, IGF-II, and insulin was typical of type I binding (IGF-I > IGF-II > insulin). Affinity cross-linking of ovarian membranes with [125I]-IGF-I revealed a radiolabeled band corresponding to a molecular weight of 135,000, the alpha subunit of the type I IGF receptor. This band was totally displaced by IGF-I and alpha IR-3. It was concluded that IGF-I stimulated follicular development, E2 production, and oocyte maturation by interacting with its specific receptor located in rabbit ovarian membranes.

Loss of transactivation and transrepression function, and not RPA binding, alters growth suppression by p53

The tumor suppressor protein p53 activates transcription from promoters with specific p53 binding elements, represses transcription from promoters without such elements and interacts with and inhibits the single-stranded DNA binding activity of the human DNA replication factor RPA. All these activities involve the N terminal 70 amino acids of p53. Dissection of the domains of p53 which bind RPA suggest that multiple sub-domains of the protein synergize to give strong RPA binding. Point-mutations in one of these sub-domains of p53 significantly diminish its ability to interact with RPA. A multimer of a peptide from p53 which includes these residues, or of a peptide from the acidic activation domain of the prototypic trans-activator protein VP16, can itself bind to RPA. Comparison of sequences of these multimeric peptides suggests that aromatic amino acids flanked by negatively charged residues are important for binding RPA. Several alleles of p53 with point mutations in the N terminal region were analysed for their relative abilities to bind RPA, activate or repress transcription, and suppress growth of p53 null SaOs2 and H1299 cells. Both mutants of p53 with decreased RPA binding suppressed cell growth as well as wild-type p53, suggesting that p53 can suppress growth without interacting with RPA. The allele that lost most of the transcription activation function also lost most of its transcription repression activity suggesting that interaction with the same basal transcription factors are involved in both functions. This same allele bound RPA well but was defective in growth suppression. Therefore, transcription activation and/or repression appear to be more important for the growth suppression function of p53 than RPA binding.

Fas-mediated apoptosis of CD4+ and CD8+ T cells from human immunodeficiency virus-infected persons: differential in vitro preventive effect of cytokines and protease antagonists

Human immunodeficiency syndrome (HIV) infection leads to a progressive loss of T-cell-mediated immunity associated with T-cell apoptosis. We report here that CD4+ and CD8+ T cells from HIV-1-infected persons are sensitive to Fas (CD95/APO-1)-mediated death induced either by an agonistic anti-Fas antibody or by the physiologic soluble Fas ligand, although showing no sensitivity to tumor necrosis factor alpha-induced death. CD4+ and CD8+ T-cell apoptosis induced by Fas ligation was enhanced by inhibitors of protein synthesis and was prevented either by a soluble Fas receptor decoy or an antagonistic anti-Fas antibody. Fas-mediated apoptosis could also be prevented in a CD4+ or CD8+ T-cell-type manner (1) by several protease antagonists, suggesting the involvement of the interleukin-1beta (IL-1beta)-converting enzyme (ICE)-related cysteine protease in CD4+ T-cell death and of both a CPP32-related cysteine protease and a calpain protease in CD8+ T-cell death; and (2) by three cytokines, IL-2, IL-12, and IL-10, that exerted their effects through a mechanism that required de novo protein synthesis. Finally, T-cell receptor (TCR)-induced apoptosis of CD4+ T cells from HIV-infected persons involved a Fas-mediated death process, whereas TCR stimulation of CD8+ T cells led to a different Fas-independent death process. These findings suggest that Fas-mediated T-cell death is involved in acquired immunodeficiency syndrome (AIDS) pathogenesis and that modulation of Fas-mediated signaling may represent a target for new therapeutic strategies aimed at the prevention of CD4+ T-cell death in AIDS.

Accumulation of deletions and point mutations in mitochondrial genome in degenerative diseases

Accumulation of various mutations in the mitochondrial genome is proposed as an important contributor to aging and degenerative diseases. Extensive fragmentation of mtDNA was detected in association with increased 8-hydroxydeoxyguanosine content in the heart mitochondrial DNA (mtDNA) from a patient with premature aging and mitochondrial cardiomyopathy, who carried a mutation within the mitochondrial tRNA(Asp) gene. This result suggests that damage to mtDNA by hydroxyl radical and accumulation of deleted mtDNA can be accelerated by a specific mitochondrial genotype. Similarly, extensive fragmentation of mtDNA was also detected in cultured cells exposed to a high oxygen concentration atmosphere, implying that mtDNA is vulnerable to reactive oxygen species. To clarify the role of point mutations accumulated in mtDNA, we examined the sequence heterogeneity of mtDNA in the skeletal muscle of a MELAS patient who carried a mutation within the mitochondrial tRNA(leu)(UUR) gene. The analysis revealed that the frequency of mutant clones in the MELAS muscle was significantly higher than those in an age-matched control muscle and a control placenta. Some of these nucleotide substitutions were missense and nonsense mutations, which potentially have deleterious effects on the mitochondrial function. The frequency of nucleotide substitutions in the striatum of three patients with Parkinson's disease was also significantly higher than that in control tissues. We also observed increased protein modification by 4-hydroxy-2-nonenal, a lipid peroxidation by-product, in Parkinson's disease. These results suggests that a vicious cycle contributes to the progression of degenerative process. In this cycle, first a primary mitochondrial mutation(s) induces a mitochondrial respiratory defect, which increases the leakage of reactive oxygen species (ROS) from the respiratory chain. Then the ROS would trigger accumulation of secondary mtDNA mutations in postmitotic cells, leading to further aggravation of mitochondrial respiratory defects and increased production of ROS and lipid peroxides from mitochondria, and thus resulting in degeneration of cellular components.