Anti-apoptotic activity of the glutathione peroxidase homologue encoded by HIV-1

The third reading frame of the envelope gene from HIV-1 codes for a protein homologous to the human selenoprotein glutathione peroxidase (GPX). Cells stably or transiently transfected with a HIV-1 GPX construct are protected against the loss of the mitochondrial transmembrane potential and subsequent cell death induced by exogenous reactive oxygen species (ROS) as well as mitochondrion-generated ROS. However, HIV-1 GPX does not confer a general apoptosis resistance, because HIV-1 GPX-transfected cells were not protected against cell death induced by staurosporine or oligomycin. The inhibition of cell death induced by the ROS donor tert-butylhydroperoxide was also observed in cells depleted from endogenous glutathione (GSH), suggesting that GSH is not the sole electron acceptor for HIV-1 GPX. Clinical HIV-1 isolates from long-term non-progressors (untreated patients with diagnosed HIV-1 infection for > 10 years, with CD4 T cell count of > 500 cells/mm3) mostly possess an intact GPX gene (with only 18% of loss-of-function mutations), while HIV-1 isolates from patients developing AIDS contain non-functional GPX mutants in 9 out of 17 cases (53%). Altogether, these data suggest that HIV-1 GPX possesses a cytoprotective, pathophysiologically relevant function.

The value of transvaginal ultrasonography in the prediction of endometrial pathologies in asymptomatic postmenopausal breast cancer tamoxifen-treated patients

OBJECTIVE

There is no established ultrasonographic endometrial cutoff value for the diagnosis of endometrial pathologies in asymptomatic postmenopausal tamoxifen (TAM)-treated patients. We attempted to seek the most accurate cutoff value.

MATERIALS AND METHODS

Multiple ultrasonographic cutoff points were evaluated by logistic regression analysis based on 279 patients who had transvaginal ultrasonographic examinations followed by endometrial histopathological analysis. Performance characteristics were calculated with correlation to the endometrial histological findings. We also calculated how many endometrial pathologies could have been left undiagnosed and the number of endometrial samplings, with different cutoff values, which could have been avoided.

RESULTS

There was a gradual increase in specificity and a gradual decrease in sensitivity of the ultrasonographic studies with the increase of endometrial thickness. More overall and more various endometrial pathologies were identified with the increase in cutoff values. The best cutoff value appeared to be 15 mm (sensitivity 37.9%, specificity 87.2%, positive predictive value 63.0%, and negative predictive value 70.2%). However, by avoiding performance endometrial sampling up to this cutoff value, 62.2% endometrial pathologies including 48 endometrial polyps, one case of endometrial hyperplasia with atypia, and one case of endometrial cancer may have been left undiagnosed. At the same time, endometrial sampling in 78.5% of cases may have been avoided.

CONCLUSION

In asymptomatic postmenopausal breast cancer tamoxifen-treated patients, the use of wider ultrasonographic endometrial cutoff values could be associated not only with the performance of fewer endometrial samplings, but also with a higher possibility of endometrial pathologies, including endometrial cancers, being left undiagnosed.

The value of sonohysterography in the prediction of endometrial pathologies in asymptomatic postmenopausal breast cancer tamoxifen-treated patients

BACKGROUND

The study evaluated the efficacy of sonohysterography in identifying endometrial pathologies in asymptomatic postmenopausal tamoxifen (TAM)-treated patients by evaluating its performance characteristics.

MATERIALS AND METHODS

Multiple assessments of sonohysterography evaluations of intrauterine mass diameter were evaluated by logistic regression analysis based on overall 85 patients (who had transvaginal ultrasonographic endometrial thickness of >/=8 mm) followed by hysteroscopy and endometrial histological findings. Performance characteristics were calculated with correlation to the endometrial histological findings.

RESULTS

The mean endometrial thickness was 14.6 +/- 6.2 mm, and the mean intrauterine mass diameter detected by SIS was 11.6 +/- 10.4 mm. There was a gradual decrease in sensitivity and gradual increase in specificity of the SIS studies with the increase in intrauterine mass diameter. False-negative and false-positive of SIS were 2.4% and 8.2%, respectively. ROC curve analysis of intrauterine mass revealed 5 mm as the best accurate cutoff value for the diagnosis of endometrial pathologies, with a sensitivity of 74.1%, specificity of 93.0%, and positive predictive value of 88.3% and negative predictive value of 84.2%. The risk of endometrial pathology was elevated by 1.37-fold, with any additional millimeter of diameter of the intrauterine mass. The mean diameter of the intrauterine mass gradually increased the greater the severity of the histological findings.

CONCLUSIONS

Sonohysterography improves the accuracy of diagnosis of intrauterine mass in asymptomatic postmenopausal tamoxifen-treated patients. The size of the intrauterine mass correlates with the severity of the endometrial pathology.

Effects of all-trans retinoic acid or chemotherapy on the molecular regulation of systemic blood coagulation and fibrinolysis in patients with acute promyelocytic leukemia

We studied the pathogenesis of the bleeding disorder in acute promyelocytic leukemia by measuring procoagulant, profibrinolytic, and proinflammatory mediators in peripheral blood and bone marrow cells from 25 previously untreated patients. Patients were induced with either all-trans retinoic acid (ATRA) or chemotherapy. Plasma levels of fibrinopeptide A (FPA), fibrin d-dimer, thrombin antithrombin (TAT) complex, prothrombin fragment 1.2 (F1.2), urokinase-type plasminogen activator (uPA), tissue-type plasminogen activator (t-PA) and plasminogen activator-inhibitor 1 (PAI-1) were measured before and after therapy, as was the cellular expression of the genes for tissue factor (TF) and interleukin-1 beta (IL-1 beta). The mean plasma levels of fibrin d-dimer, F1.2, TAT and FPA were markedly elevated prior to therapy and declined during the first 30 days of treatment with either ATRA or chemotherapy, but more rapidly and to a greater extent in patients treated with ATRA. ATRA treatment was associated with a significant decrease in TF gene expression in bone marrow cells during the first 30 days of treatment, whereas IL-1 beta gene expression, which decreased in the cells of six patients treated with either chemotherapy or ATRA, actually increased in the remaining six patients treated with either chemotherapy or ATRA. In patients with APL, treatment with either chemotherapy or ATRA rapidly ameliorates the coagulopathy, as indicated by an abrupt decline in markers of clotting activation. An increase in cytokine gene expression (e.g. IL-1 beta) may provide an explanation for the persistent hypercoagulability observed in some patients with APL, regardless of therapeutic approach. Our data confirms and extends earlier observations by others that ATRA is more effective than chemotherapy alone in rapidly reducing the procoagulant burden of APL tumor cells. However, our data also suggests that cytokine expression in some patients may be accelerated by either chemotherapy or ATRA. The implications of this observation for understanding the retinoic acid syndrome will require further studies.

RNA binding activity of the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit from Chlamydomonas reinhardtii

Transfer of the green algae Chlamydomonas reinhardtii from low light to high light generated an oxidative stress that led to a dramatic arrest in the synthesis of the large subunit (LSU) of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). The translational arrest correlated with transient changes in the intracellular levels of reactive oxygen species and with shifting the glutathione pool toward its oxidized form (Irihimovitch, V., and Shapira, M. (2000) J. Biol. Chem. 275, 16289-16295). Here we examined how the redox potential of glutathione affected the RNA-protein interactions with the 5'-untranslated region of rbcL. This RNA region specifically binds a group of proteins with molecular masses of 81, 62, 51, and 47 kDa in UV-cross-linking experiments under reducing conditions. Binding of these proteins was interrupted by exposure to oxidizing conditions (GSSG), and a new protein of 55 kDa was shown to interact with the RNA. The 55-kDa protein comigrated with Rubisco LSU in one- and two-dimensional gels, and its RNA binding activity was further verified by using the purified protein in UV-cross-linking experiments under oxidizing conditions. However, the LSU of purified and oxidized Rubisco bound to RNA in a sequence-independent manner. A remarkable structural similarity was found between the amino-terminal domain of Rubisco LSU in C. reinhardtii and the RNA binding domain, a highly prevailing motif among RNA-binding proteins. It appears from the crystal structure of Rubisco that the amino terminus of LSU is buried within the holoenzyme. We propose that under oxidizing conditions it is exposed to the surface and can, therefore, bind RNA. Accordingly, a recombinant form of the polypeptide domain that corresponds to the amino terminus of LSU was found to bind RNA in vitro with or without GSSG.

Mitochondrial permeability transition as a novel principle of hepatorenal toxicity in vivo

Atractyloside (Atr) binds to the adenine nucleotide translocator (ANT) and inhibits ANT-mediated ATP/ADP exchange on the inner mitochondrial membrane. In addition, Atr can trigger opening of a non-specific ion channel, within the ANT-containing permeability transition pore complex (PTPC), which is subject to redox regulation and inhibited by cyclosporin A (CsA). Here we show that the cytotoxic effects of Atr, both in vivo and in vitro, are determined by its capacity to induce PTPC opening and consequent mitochondrial membrane permeabilization (MMP). Thus, the Atr-induced MMP and death of cultured liver cells are both inhibited by CsA as well as by glutathione (GSH) and enhanced by GSH depletion. Similarly, the hepatorenal toxicity of Atr, assessed in vivo, was reduced by treating mice with CsA or a diet rich in sulfur amino acids, a regime which enhances mitochondrial GSH levels. Atr injection induced MMP in hepatocytes and proximal renal tubular cells, and MMP was reduced by either CsA or GSH. Acetaminophen (paracetamol)-induced acute poisoning was also attenuated by CsA and GSH, both in vitro and in vivo. Altogether these data indicate that PTPC-mediated MMP may determine the hepatorenal toxicity of xenobiotics in vivo.

Use of herbs in women diagnosed with ovarian cancer

Of 113 consecutive ovarian cancer patients identified in a gynecologic clinic in a major academic medical center in San Francisco, 41 patients were successfully contacted, were eligible, and participated in a telephone survey. We contacted women identified consecutively in the clinic database as having ovarian cancer and sent a letter introducing our research team and asking for help. Members of the research team then contacted the women to conduct the telephone interviews. Fifty-one percent (95% CI 35-67) of the women had taken herbs sometime since they were diagnosed with ovarian cancer. Most herb uses occurred concurrently with chemotherapy. Only 12% (95% CI 4-26) used an herbalist or other health practitioner for guidance in herb use. Only one woman took herbs instead of chemotherapy. A large number of women attending our practice in the San Francisco Bay area use herbs as complementary medicine during their cancer treatment.

Activation of p53 protein by telomeric (TTAGGG)n repeats

Genome instability is a primary factor leading to the activation of the p53 tumor suppressor protein. Telomeric repeat (TR) sequences are also responsible for genome integrity. By capping the termini of the chromosomes, TRs prevent them undergoing nucleolytic degradation, ligation or chromosome fusion. Interestingly, telomere shortening was suggested to activate p53, which in turn may cause primary cells to senesce. In order to elucidate the nature of a possible cross talk between the two, we introduced into cells TRs of defined length and investigated their effect on p53 activation and subsequent cellular response. We found that the introduction of a TR into cells leads to stabilization of the p53 protein. This stabilization was specific to TRs and was not observed in response to exposure of cells to plasmids containing non-TR sequences. p53 stabilization requires the presence of an intact p53 oligomerization domain. TR-activated p53 exhibited enhanced transcriptional activity. Eventually, TRs induced p53-dependent growth suppression, measured as a reduction in colony formation.

Work in progress. Integrating physicians' services in the home

OBJECTIVE

While increasing acuity levels and the concomitant complexity of service demand that physicians be involved in in-home care, conflicting evidence and opinions do not show how this can best be achieved.

DESIGN

A phenomenologic research design was used to obtain insights into the challenges and opportunities of integrating physicians' services into the usual in-home services in London, Ont.

SETTING

Home care in London, Ont.

PARTICIPANTS

Twelve participants included three patients, two family caregivers, two family physicians, the program's nurse practitioner, two case managers, and two community nurses.

METHOD

In-depth interviews with a maximally varied purposeful sample of patients, caregivers, and providers were analyzed using immersion and crystallization techniques.

MAIN FINDINGS

Findings revealed the potential for enhanced continuity of care and interdisciplinary team functioning. Having a nurse practitioner, interdisciplinary team-building exercises and meetings, regular face-to-face contact among all providers, support for family caregivers, and 24-hour coverage for physicians were found to be essential for success.

CONCLUSION

Integration of services takes time, money, and sustained commitment, particularly when undertaken in geographically isolated communities. Informed choice and a fair remuneration system remain important considerations for family physicians.

Adenine nucleotide translocator mediates the mitochondrial membrane permeabilization induced by lonidamine, arsenite and CD437

An increasing number of experimental chemotherapeutic agents induce apoptosis by directly triggering mitochondrial membrane permeabilization (MMP). Here we examined MMP induced by lonidamine, arsenite, and the retinoid derivative CD437. Cells overexpressing the cytomegalovirus-encoded protein vMIA, a protein which interacts with the adenine nucleotide translocator, were strongly protected against the MMP-inducing and apoptogenic effects of lonidamine, arsenite, and CD437. In a cell-free system, lonidamine, arsenite, and CD437 induced the permeabilization of ANT proteoliposomes, yet had no effect on protein-free liposomes. The ANT-dependent membrane permeabilization was inhibited by the two ANT ligands ATP and ADP, as well as by recombinant Bcl-2 protein. Lonidamine, arsenite, and CD437, added to synthetic planar lipid bilayers containing ANT, elicited ANT channel activities with clearly distinct conductance levels of 20+/-7, 100+/-30, and 47+/-7 pS, respectively. Altering the ATP/ADP gradient built up on the inner mitochondrial membrane by inhibition of glycolysis and/or oxidative phosphorylation differentially modulated the cytocidal potential of lonidamine, arsenite, and CD437. Inhibition of F(0)F(1)ATPase without glycolysis inhibition sensitized to lonidamine-induced cell death. In contrast, only the combined inhibition of glycolysis plus F(0)F(1)ATPase sensitized to arsenite-induced cell death. No sensitization to cell death induction by CD437 was achieved by glucose depletion and/or oligomycin addition. These results indicate that ANT is a target of lonidamine, arsenite, and CD437 and unravel an unexpected heterogeneity in the mode of action of these three compounds.

Ambulatory blood pressure monitoring in children with a solitary kidney - a comparison between unilateral renal agenesis and uninephrectomy

BACKGROUND

In experimental animals, a reduction in renal mass leads to glomerulosclerosis of the residual parenchyma and eventual renal failure. In humans, however, data on the influence of nephrectomy or agenesis on future functional parameters and hypertension are as yet controversial.

OBJECTIVE

To evaluate blood-pressure patterns in children with a solitary kidney as a result of either unilateral renal agenesis (URA) or uninephrectomy (UNX) and correlate them to the increase in size of the remaining kidney.

METHODS

Twenty-eight children with a solitary kidney were divided into two groups: the URA group, with 18 subjects (13 male and five female, with a mean age of 9.6 +/- 3.9 years), and the UNX group, which contained 10 subjects (four male and six female, with a mean age of 14.0 +/- 2.7 years). The mean time since nephrectomy was 8.7 years. Each study group was assigned an age-, weight- and height-matched control group. In all subjects, ambulatory blood pressure monitoring was performed using the SpaceLabs model no. 90207. Daytime and night-time were defined as 0800-2200 h and 2200-0800 h, respectively. Urinalysis, serum creatinine and urea results were recorded for all the study group participants. The size of the remaining kidney was determined by ultrasound examination. The percentage increase in kidney size, as calculated from standard kidney-length-against-age nomograms was correlated to the percentage deviation from normal blood pressure values.

RESULTS

The mean 24 h, daytime and night-time systolic blood pressure (SBP) readings were significantly higher in children in the URA group than in those in the corresponding control group (111.4 +/- 7.5 mmHg versus 106.9 +/- 6.7 mmHg, P < 0.004; 115.2 +/- 3.1 mmHg versus 110.7 +/- 3.4 mmHg, P < 0.004; and 105.2 +/- 2.6 mmHg versus 101.2 +/- 1.8 mmHg, P < 0.002, respectively). Daytime heart rate was found to be significantly reduced (84.4 +/- 5.2 versus 87.8 +/- 8.2 beats/min, P < 0.04). In the UNX group, 24 h mean, systolic and diastolic blood pressure (DBP), as well as heart rate, did not differ from control values. Daytime systolic and diastolic blood pressures were higher than those of the controls (119.8 +/- 4.0 mmHg versus 115.5 +/- 3.8 mmHg, P < 0.02; and 72.7 +/- 4.0 mmHg versus 70.0 +/- 11.0 mmHg, P < 0.02, respectively). Nocturnal dipping was present in all groups and was of equal magnitude in the corresponding control groups. The mean 24 h diastolic blood pressure load was significantly greater in URA patients than in controls (19.6 versus 10.8%, respectively, P < 0.01). In the UNX group, the blood pressure loads were similar to those of controls. The percentage increase in length of the remaining kidney was found to correlate positively with the percentage delta increase in both systolic and diastolic blood pressure.

CONCLUSIONS

Compared with the age-, height- and weight-matched controls, the children with a solitary kidney caused by URA had an elevated mean 24 h SBP. In contrast, those with UNX had mean 24 h blood pressure values similar to those of their controls. A rise in SBP was, however, seen in both groups during the daytime hours. Thus, the presence of a solitary kidney, for whatever reason, may be pathogenetically linked to a raised blood pressure, and this linkage may be more pronounced in URA. The delta increase in size of the remaining kidney may serve as a prognostic indicator of blood pressure elevation.

Ultrasonography as a diagnostic modality in Osgood-Schlatter disease. A clinical study and review of the literature

Sonographic examination of the knee has been proposed by several authors in the past as a simple and reliable method to diagnose Osgood-Schlatter disease (OSD). Ultrasound was used to compare the knees of 25 boys and 10 girls with typical OSD with 35 symptom-free knees of an aged-matched group of children. Based on recorded data, patients were categorized (one affected knee in each individual) according to the classification system proposed by De Flaviis et al. in 1989. The results included the following pathological findings: pretibial swelling, fragmentation of the ossification center, insertional thickening of the patellar tendon, and excessive fluid collection in the infrapatellar bursa. Of our patients, 26% fell into the type 1 category, 43% were type 2, 20% type 3, and 11% type 4. This distribution of cases was found to be statistically similar to the initial findings reported by De Flaviis and colleagues. This study therefore supports the validity and reproducibility of their classification method for the ultrasonographic evaluation of children with OSD. This is only the first step, and further assessment of this classification is still required to elucidate its clinical as well as its prognostic value.

Cytological diagnosis of primary leiomyosarcoma of bone: case report

We report on a case of primary leiomyosarcoma of the bone in a 77-yr-old man. The patient presented with a painful, enlarging mass in the left shoulder of 6 mo duration. Radiography and computed tomography (CT) revealed a large destructive intramedullary lesion of the proximal humerus, with massive extension into the surrounding soft tissues. CT-guided fine-needle aspiration biopsies (FNAB) of both the bony and soft-tissue lesions were performed. Cytological examination showed a neoplastic process composed of spindle cells mixed with pleomorphic cells. The smooth muscle origin of the neoplastic cells was confirmed by immunocytochemical analysis. We describe the cytological features of this rare primary tumor of bone, and consider the differential diagnosis of spindle-cell neoplasms.

Risk factors of endometrial polyps resected from postmenopausal patients with breast carcinoma treated with tamoxifen

BACKGROUND

Endometrial polyps are the most common endometrial pathology described in association with postmenopausal tamoxifen exposure. Up to 3% of these polyps may show malignant changes. However, to the authors' knowledge no one has described any risk factor for the development of this pathology in postmenopausal patients with breast carcinoma treated with tamoxifen. OBJECTIVE. The objective of this study was to evaluate whether risk factors can be identified for the development of endometrial polyps in postmenopausal patients with breast carcinoma treated with tamoxifen.

METHODS

The authors reviewed the medical records of 54 postmenopausal patients with breast carcinoma in whom endometrial polyps were resected by hysteroscopy after at least 6 months of tamoxifen treatment (Group I). Demographic characteristics, health habits, risk factors for endometrial carcinoma, and clinical factors related to the primary breast disease were examined. The results were compared with those obtained from 210 similar patients in whom hysteroscopy did not reveal any endometrial pathology (Group II).

RESULTS

Age at menopause was significantly older, duration of breast disease was significantly longer, and body weight was significantly heavier among Group I patients compared with Group II patients (P = 0.0162, P = 0.0026, and P = 0.0364, respectively). Endometrial thickness, measured by transvaginal ultrasonography, was significantly thicker in Group I patients (16.3 +/- 7.2 mm) compared with that detected in Group II patients (11.8 +/- 6.3; P = 0.0001).

CONCLUSIONS

Various factors, such as older age at menopause, longer duration of breast disease, heavier weight, and thicker endometrium may contribute to the prediction of increased risk of development of endometrial polyps in postmenopausal patients with breast carcinoma treated with tamoxifen.