Search PubMed⌕ Search

Biomedical subjects

D Venzon

Publications and source records attributed to D Venzon.

At least 91 records · Page 5Linked to original sources

Tempol, a stable free radical, is a novel murine radiation protector.

Nitroxide compounds are stable free radicals which were previously investigated as hypoxic cell radiosensitizers. The stable nitroxide 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (Tempol) has recently been shown to protect aerated cells in culture against superoxide generated from hypoxanthine/xanthine oxidase, hydrogen peroxide, and radiation-induced cytotoxicity and to modestly sensitive hypoxic cultured cells. To extend these observations from the cellular level to the whole animal, the toxicity, pharmacology, and in vivo radioprotective effects of Tempol were studied in C3H mice. The maximum tolerated dose of Tempol administered i.p. was found to be 275 mg/kg, which resulted in maximal Tempol levels in whole blood 5-10 min after injection. Mice were exposed to whole-body radiation in the absence or presence of injected Tempol (275 mg/kg) 5-10 min after administration. Tempol treatment provided significant radioprotection (P less than 0.0001); the dose of radiation at which 50% of Tempol-treated mice die at 30 days was 9.97 Gy, versus 7.84 Gy for control mice. Tempol represents a new class of in vivo, non-sulfur-containing radiation protectors. Given the potential for hypoxic radiosensitization and aerobic cell radioprotection, Temporal or other analogues may have potential therapeutic application.

Animals↗

CD4 status and P24 antigenemia. Are they useful predictors of survival in HIV-infected children receiving antiretroviral therapy?

OBJECTIVE: To determine the relationship between CD4 status and the P24 antigen level and survival in children infected with the human immunodeficiency virus. DESIGN: Cohort, case-control. SETTING: Clinical Center at the National Institutes of Health, Bethesda, Md. PARTICIPANTS: One hundred forty-seven children infected with the human immunodeficiency virus enrolled in antiretroviral therapy protocols at the National Cancer Institute were reviewed and the relationships between CD4 counts, P24 antigenemia, and death were analyzed. INTERVENTIONS: None. MEASUREMENTS/MAIN RESULTS: The presence of a very low CD count, less than 21% of the lower limit of normal values for age (equivalent to 0.05 x 10(9)/L in an adult), was associated with a significantly increased risk of death within 2 years. Although the risk of death was highest for children with CD4 counts below this level and who had detectable P24 antigen levels, P24 antigenemia by itself contributed little to the prognostic value of the CD4 count alone. However, it was also notable that a group of children with low CD4 counts also experienced prolonged survival. CONCLUSIONS: The association between low CD4 counts and death suggests that the age-adjusted CD4 count should be used as a marker to guide therapeutic intervention. At the same time, the presence of a very low CD4 count alone should not be considered a reason for therapeutic nihilism.

Age Factors↗

The effect of systemic therapy on local-regional control in locally advanced breast cancer.

One hundred and seven patients with locally advanced breast cancer were prospectively referred for multimodality treatment on protocol using chemohormonal therapy to maximal response followed by local treatment and maintenance therapy. Forty-eight patients (45%) were diagnosed with Stage IIIA disease, 46 (43%) with Stage IIIB inflammatory cancer, and 13 (12%) with Stage IIIB non-inflammatory disease. Induction therapy consisted of cyclophosphamide, doxorubicin, methotrexate, and 5-fluorouracil with hormonal synchronization using tamoxifen and conjugated estrogens. Local treatment was determined by response to chemotherapy. Patients with a clinical parital response underwent mastectomy followed by local-regional radiotherapy while patients with a clinical complete response were biopsied for pathologic correlation. Those with residual disease received mastectomy followed by radiotherapy while those with a pathologic complete response received radiation only to the intact breast and regional nodes. With a median follow-up of 64 months, patients with IIIA disease had a significantly lower local-regional failure rate compared to IIIB inflammatory patients, with the 5-year actuarial local-regional failure rate as only site of first failure 3% for IIIA disease versus 21% for IIIB inflammatory cancer (p = .02), and local-regional failure as any component of first failure 12% versus 36% (p = .01), respectively. When local-regional failure was analyzed by repeat biopsy, 5/31 (16%) patients with a pathologic complete response treated with radiation only developed a local-regional failure versus 2/53 (4%) with residual disease treated with mastectomy and postoperative radiotherapy. The 5-year actuarial local-regional failure rate as first site of failure was 23% for radiation only versus 5% for mastectomy and post-operative radiotherapy (p = .07). The response to chemotherapy did not reliably predict local-regional control. Both relapse-free survival and overall survival were significantly better for IIIA versus IIIB patients; stratification by repeat biopsy did not however, significantly affect either relapse-free or overall survival.

Adult↗

Bilateral distribution of aminopeptidase activities in selected structures of a photoneuroendocrine circuit and other rat brain areas.

Provided that soluble aminopeptidases, the most abundant proteolytic enzymes found in brain, are involved in the metabolism of several neuropeptides, their activity could be a reflect of neuropeptide function. Therefore, in order to analyze their rate of participation, we have measured 4 soluble aminopeptidase activities: leucine aminopeptidase, arginine aminopeptidase, aspartate aminopeptidase, and pyroglutamate aminopeptidase, using arylamide derivatives as substrates, in selected structures integrating the photoneuroendocrine circuit related to the melatonin rhythm generating system and other rat brain areas. The regional distribution of all the activities was heterogenous: a 3-fold (leucine-, arginine- and aspartate-aminopeptidase) and 5-fold (pyroglutamate aminopeptidase) difference was observed between the regions with the highest and lowest activity. Significant differences were displayed between the left and right retina for pyroglutamate aminopeptidase and arginine aminopeptidase activities. High levels of pyroglutamate aminopeptidase were evident in the retina and adenohypophysis, which is consistent with a role for thyrotropin releasing hormone in photoreceptive mechanisms, and support its well established role in controlling thyrotropin releasing hormone in anterior pituitary. The presence of a high activity rate of aspartate aminopeptidase in adenohypophysis implies an active participation of angiotensin peptides at this level.

Aminopeptidases↗

Neutrophil oxidative burst in response to blastoconidia and pseudohyphae of Candida albicans: augmentation by granulocyte colony-stimulating factor and interferon-gamma.

The effects of granulocyte colony-stimulating factor (G-CSF) and interferon-gamma (IFN-gamma) on the oxidative burst of neutrophils (PMNL) in response to blastoconidia and pseudohyphae of Candida albicans were assessed and compared with those in response to N-FMLP. G-CSF enhanced oxidative burst, as measured by superoxide production, in response to both FMLP and opsonized blastoconidia. The enhancement of oxidative burst in response to FMLP was significantly greater (P = .004) than that in response to blastoconidia (65% and 39%, respectively). G-CSF also enhanced oxidative burst in response to pseudohyphae. IFN-gamma enhanced oxidative burst in response to FMLP and opsonized blastoconidia by 53% and 50%, respectively. Moreover, IFN-gamma significantly enhanced oxidative burst in response to opsonized and nonopsonized hyphae by 86% and 65%, respectively. These results demonstrate that G-CSF and IFN-gamma enhance the oxidative burst of PMNL in response to both blastoconidia and pseudohyphae of C. albicans and suggest an immunomodulatory role of the two cytokines in the host defenses against this fungus.

Adult↗

Role of tumor necrosis factor in oxygen toxicity.

mRNA from lungs of mice exposed to high-dose oxygen (greater than 95%) for 3 days demonstrated increased expression of the genes for tumor necrosis factor (TNF), interleukin-1, and interleukin-6 compared with mRNA from lungs of mice exposed to room air. Daily treatment of mice exposed to high-dose oxygen with an antibody to TNF improved survival compared with mice receiving a similar dose of control immunoglobulin G. Pretreatment of mice with repetitive sublethal intraperitoneal doses of recombinant human TNF for 3 days or a single intravenous dose followed by exposure to high-dose oxygen afforded a significant survival advantage compared with high-dose oxygen-exposed mice pretreated with vehicle or interleukin-1. The repetitive intraperitoneal TNF pretreatment reduced the development of interstitial pneumonitis, pulmonary edema, and lung weight gain associated with oxygen toxicity and enhanced expression of the gene for the free radical protective enzyme manganous superoxide dismutase in lung tissue, a gene that is augmented as mice are exposed to high-dose oxygen. Furthermore a single intravenous dose of TNF 24 h after oxygen exposure was still protective. The results suggest that the toxicity of oxygen therapy can be partially ameliorated by either treatment with anti-TNF antibody or pretreatment and early treatment with TNF. These findings are consistent with the hypothesis that oxygen exposure induces TNF, which causes part of the toxicity of high-dose oxygen, and that pretreatment or early treatment with TNF induces the gene for an enzyme that recently has been shown to be very effective in protecting mice from the toxicity of oxygen.

Animals↗

Daily rhythm of aspartate aminopeptidase activity in the retina, pineal gland and occipital cortex of the rat.

The levels of specific soluble aspartyl aminopeptidase activity were assayed in retina, occipital cortex, anterior pituitary, posterior pituitary, pineal gland and serum of adult male rats, using Asp-2-naphthylamide as substrate, in a 12:12 h light:dark cycle (7-19 h light). Significant diurnal variations appeared in retina, pineal gland, occipital cortex and serum. In addition, different patterns of diurnal variation of the enzymatic activity were observed in the tissues analyzed. A regular increase of the activity was noticed at the end of the dark period in all the tissues as a common feature, except in serum, in which the enzymatic activity reached a peak in the middle of the light period, decreasing progressively during the dark hours. After the last hours of darkness, the pattern of variation in the activity differed in each tissue. These diurnal variations in aspartyl aminopeptidase activity could reflect the functional status of its putative endogenous substrates, such as angiotensin II, and it may also suggest the existence of differential regulatory mechanisms associated with each location.

Aminopeptidases↗

A prospective randomized trial comparing the infectious and noninfectious complications of an externalized catheter versus a subcutaneously implanted device in cancer patients.

PURPOSE: To compare the frequency of infectious episodes or other problems occurring with an externalized catheter (Hickman) versus a subcutaneously implanted device (Port-a-Cath, Pharmacia, Piscataway, NJ) in cancer patients, we performed a prospective, randomized study in 100 cancer patients (age range, 5 to 74 years). PATIENTS AND METHODS: Patients who were chemotherapy candidates and required an indwelling catheter were monitored prospectively and evaluated during the 180 days after the insertion of the catheter and again at time of study closure. The frequency of catheter use, reason for access, and any problems that might have been related to catheter use were noted. All data were collected prospectively and included the patient's age, sex, underlying malignancy, temperature, and leukocyte and absolute granulocyte counts at the time of catheter insertion and when complications occurred. The time to and reason for removal of the catheter, as well as any intercurrent infectious or mechanical problems, were also determined. RESULTS: Most of the infections that occurred were caused by gram-positive organisms, especially staphylococci or streptococci. A total of 22 complications (11 in each group) resulted in removal of the central line. Only one infection in the Hickman catheter group and four in the Port-a-Cath group led to removal of the central line. All other infectious episodes were successfully treated without removal of the catheters. The mean device life was 230 days for the Hickman catheter and 318 days for the Port-a-Cath (not significant). CONCLUSION: There were no differences between the two study groups regarding incidence of documented infections or mechanical or thrombotic complications.

Adolescent↗

Suramin inhibits bone resorption and reduces osteoblast number in a neonatal mouse calvarial bone resorption assay.

The antineoplastic properties of suramin, a polyanionic agent with demonstrated antigrowth factor activity, are under evaluation in vitro, in vivo, and in clinical trials. Suramin has been shown to have antitumor activity in patients with advanced, hormone refractory prostate cancer. During these trials, significant resolution of osseous pain was observed in nearly three quarters of the patients treated with suramin. To evaluate the effect of suramin on bone cells, we studied the effect of suramin on bone resorption in a neonatal mouse calvarial assay. Suramin inhibited bone-resorbing activity in a dose-related fashion and had an additive effect with calcitonin. Calvaria pretreated with suramin had less bone-resorbing activity, fewer attached osteoblasts, and less medium alkaline phosphatase activity than control calvaria. Suramin also inhibited osteoclastic release of tritiated proline from labeled bone in a dose-dependent fashion. The effect of metastatic prostate carcinoma on bone is incompletely understood, but may be moderated by tumor-produced factors and/or cytokines. The effects of several such agents, therefore, were examined in combination with suramin. Bone resorption induced by PTH, epidermal growth factor, tumor necrosis factor, and a tumor-produced factor, PTH related-protein, was blocked by suramin. The ability of suramin to inhibit the bone-resorbing effects of several cytokines suggests that its mechanism may involve direct action on bone metabolism. Autoradiography performed on calvaria treated with labeled suramin demonstrated heavy deposition of suramin on the outer surface of the matrix, adjacent to osteoblasts and osteoclasts lining the outer table, suggesting that bone cells may be subject to high local concentrations of the drug, in keeping with this hypothesis.

Alkaline Phosphatase↗

Association between histological type and neuroendocrine differentiation on drug sensitivity of lung cancer cell lines.

Because most small-cell lung cancers (SCLC) are initially chemosensitive and express neuroendocrine (NE) cell markers and most non-SCLC tumors (NSCLC) are chemoresistant and do not express NE cell markers, we investigated the association between morphological type and NE cell differentiation with in vitro chemosensitivity. We tested a panel of 55 lung cancer cell lines established from previously untreated patients. These were tested against five cytotoxic drugs commonly used in the therapy of lung cancer, using the MTT assay. For comparative purposes, we also tested cell lines established from previously treated patients with SCLC and from colorectal tumors. The logarithms of the IC50 values of all of the cell lines were normally distributed, permitting the use of Student's t-test for assessment of differences. In general, the in vitro sensitivities of SCLC, NSCLC, and colorectal cell lines mirrored the clinical experience with these tumor types. Cell lines started from previously treated patients with SCLC were more resistant than those from previously untreated patients who responded to initial therapy. For all of the cell lines, the sensitivities to the five drugs tested were highly significantly correlated with each other. Thus, for comparative purposes, each group could be assigned an average standardized mean rank. About 15% of NSCLC tumors express multiple neuroendocrine (NE) cell markers and 4 of 5 lines from these NSCLC-NE tumors were relatively chemosensitive, similar to SCLC lines and significantly different from other NSCLC lines. Other NE cell lines tested included bronchial carcinoids and cell lines from small-cell carcinomas arising in extra-pulmonary locations (ExPuSC).(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Non-Small-Cell Lung↗

Identification of nitroxide radioprotectors.

The nitroxide Tempol, a stable free radical, has recently been shown to protect mammalian cells against several forms of oxidative stress including radiation-induced cytotoxicity. To extend this observation, six additional water-soluble nitroxides with different structural features were evaluated for potential radioprotective properties using Chinese hamster V79 cells and clonogenic assays. Nitroxides (10 mM) were added 10 min prior to radiation exposure and full radiation dose-response curves were determined. In addition to Tempol, five of the six nitroxides afforded in vitro radioprotection. The best protectors were found to be the positively charged nitroxides, Tempamine and 3-aminomethyl-PROXYL, with protection factors of 2.3 and 2.4, respectively, compared with Tempol, which had a protection factor of 1.3. 3-Carboxy-PROXYL, a negatively charged nitroxide, provided minimal protection. DNA binding characteristics as studied by nonequilibrium dialysis of DNA with each of the nitroxides demonstrated that Tempamine and 3-amino-methyl-PROXYL bound more strongly to DNA than did Tempol. Since DNA is assumed to be the target of radiation-induced cytotoxicity, differences in protection may be explained by variabilities in affinity of the protector for the target. This study establishes nitroxides as a general class of new nonthiol radioprotectors and suggests other parameters that may be exploited to find even better nitroxide-induced radioprotection.

Animals↗

Long-term follow-up of Ewing's sarcoma of bone treated with combined modality therapy.

Between 1968 and 1980, 107 consecutive patients with Ewing's sarcoma of bone were entered on three sequential combined modality treatment protocols (S2, S3, S4) at the National Cancer Institute (NCI). Protocol treatment involved 4 cycles of two drug [cyclophosphamide (CTX) and vincristine (VCR)] or three drug [CTX and VCR with either actinomycin-D (ACT-D) or doxorubicin (ADR)] regimens and local irradiation (50 Gy) to the involved bone. Eighty patients presented with localized disease and 27 patients had metastatic disease at presentation, including 11 patients with multiple metastatic sites. With a median potential follow-up of greater than 15 yrs (range 8-20 yrs), 28 pts (27%) remain alive. Disease-free (DFS) and overall survival (OS) decreased most rapidly during the initial 5 yrs of follow-up with 5-yr DFS of 29% and 5-yr OS of 39%. Only two patients with metastases at presentation are long term (greater than 5 yr) survivors. For localized disease patients, the 2, 5, 10, and 15 yr DFS and OS are 52%, 37%, 35%, and 33% DFS and 68%, 51%, 39%, and 34% OS, respectively. Eleven patients relapsed locally as the first site of failure. Using the Cox proportional hazards model, four significant variables for both DFS and OS were recognized, including metastatic disease at presentation, age greater than 25 yrs, high LDH in localized disease patients, and central primary tumor in localized disease patients in decreasing order of significance. We conclude that a majority of these patients with Ewing's sarcoma of bone relapsed within 5 yrs of presentation although late relapse (5-15 yrs) did occur. Local failure occurred in 20% of patients using these combined modality treatments but had no impact on overall survival.

Adolescent↗

Acute and long-term effects on limb function of combined modality limb sparing therapy for extremity soft tissue sarcoma.

A retrospective review is presented on 145 patients who underwent limb-sparing surgery and radiation therapy (with or without adjuvant chemotherapy) for their primary soft tissue sarcomas of the extremities on protocol between 1975 and 1986. The focus on our analysis was the acute and long term toxicity of treatment on limb function. The most common acute complication was skin reaction, occurring in 52 patients (36%). Long term (occurring after more than 1 year following all treatment) treatment complications in the extremity were as follows: bone fracture = 6%; contracture = 20%; pain requiring narcotics = 7%; edema greater than 2+ = 19%; moderate to severe decrease in range of motion = 32%; moderate to severe decrease in manual muscle strength = 20%; orthotic device required = 9%; cane or crutch required = 7%; chronic infection = 9%; and tissue induration = 57%. Three amputations for treatment complications were required. Inclusion of more than 50% of the joint in the radiation portal was associated with a higher frequency of contracture. High nominal standard dose (greater than 1760 rets, greater than 63 Gy at 1.8 Gy per fraction) resulted in more painful limbs as well as limbs with increased edema, decreased manual muscle strength, decreased range of motion, and skin telangiectasias. Edema was more often noted in patients with a longer radiation portal (greater than 35 cm), as was tissue induration. Chronic ulcer or infection was more frequently seen in patients with lower extremity tumors and when more than 75% of the extremity diameter was irradiated. Although chemotherapy given concurrent with radiation therapy was associated with a higher number of acute skin reactions, this did not appear to translate into increased long term morbidity. The percentage of patients ambulating without assistive devices and with mild or no pain was 84%. Careful attention to the techniques of radiation therapy may have a significant impact on minimizing acute and long term complications of limb sparing treatment for extremity soft tissue sarcoma.

Combined Modality Therapy↗

Cytometry and morphometry of malignant fibrous histiocytoma of the extremities. Prediction of metastasis and mortality.

Flow cytometry and nuclear morphometry were compared with traditional pathologic grading techniques for predicting the course of malignant fibrous histiocytoma of the extremities. Clinical, pathologic, and flow/morphometric variables from 53 cases were tested by Cox regression for prediction of distant recurrence and mortality. Tumor grading based on extent of tumor necrosis was a significant predictor for both disease-free survival (p = .014) and overall survival (p = .003). The fraction of nuclei in the S + G2M segment of DNA histograms was significant for disease-free survival (p = .007), and remained significant (p = .033) in a joint Cox model with necrosis-based grade (p = .004 for the bivariate model). Relative risk for recurrence varied nearly 10x between the 10th and 90th percentiles of grade and (S + G2M)1/2. Overall survival was predicted by a nuclear shape feature termed "R" (p = .000008), the casewise difference (residual) between expected and observed nuclear perimeter as a function of average Feret diameter. In a bivariate Cox model, relative risk of mortality varied 35x between the 10th and 90th percentiles of grade and R. Cytometric and morphometric data contain information about recurrence-free and overall survival beyond that available from more usual clinical and pathologic features. It seems likely that nuclear morphometry, in particular, will prove to be a useful aid for estimating the prognosis of patients with malignant fibrous histiocytoma of the extremities.

DNA, Neoplasm↗

Serum immunoglobulin G subclasses in children infected with human immunodeficiency virus type 1.

We studied serum concentrations of IgG subclasses in 47 human immunodeficiency virus 1-infected (17 asymptomatic and 30 symptomatic) children. Thirty-nine of 47 (83%) had an abnormality of at least 1 subclass. Sixteen had only elevated IgG1, 6 had only elevated IgG3 and 12 had elevated IgG1 and IgG3 concentrations. IgG2, IgG4 and combined IgG2-IgG4 deficiency was found in 3, 4 and 4 patients, respectively. IgG2 concentrations did not differ between patients with (n = 23) or without (n = 24) bacterial infections. Additionally the number of bacterial infections was similar between the patients with normal or low IgG2 and/or low IgG4. These data indicate that IgG subclass abnormalities are found in most children with human immunodeficiency virus 1 infection, but quantitative deficiencies of specific subclasses do not appear to explain the high frequency of bacterial infections occurring in these patients.

Acquired Immunodeficiency Syndrome↗

Bacterial infections in human immunodeficiency virus type 1-infected children: the impact of central venous catheters and antiretroviral agents.

We conducted a retrospective study to analyze the impact of central venous catheters (CVCs) and antiretroviral therapy on the frequency and the patterns of bacterial infections in children infected with human immunodeficiency virus during a 3-year period. Among 204 bacterial infections other than otitis media reviewed, soft tissue infection (n = 69), bacteremia (n = 57), pneumonia (n = 27) and sinusitis (n = 27) were encountered most frequently. Catheter-related staphylococcal infection was the most common infection in children with CVCs, particularly in those who were less than 6 years old. In children without CVCs, Streptococcus pneumoniae was the most frequent organism. Younger children had more CVC-related infections whereas children with lower CD4 counts had more CVC-related and CVC-unrelated infections. A lower frequency of CVC-unrelated infections was detected in patients who received antiretroviral therapy, especially those receiving a continuous infusion of zidovudine. These data suggest that increased frequency and altered patterns of bacterial infections are associated with the use of CVCs in these patients, but antiretroviral therapy may reduce the frequency of CVC-unrelated infections.

Adolescent↗

Treatment with recombinant human tumor necrosis factor-alpha protects rats against the lethality, hypotension, and hypothermia of gram-negative sepsis.

Tumor necrosis factor (TNF) is a peptide secreted by macrophages in response to endotoxin that can produce many of the changes seen in septic shock. After cecal ligation and puncture (CLP) rats gradually develop tachycardia, hypotension, tachypnea, and hypothermia. At 5 h post-CLP, rats have a peak in serum levels of endotoxin and 60% of rats have blood cultures that grow Gram-negative rods (Escherichia coli and Klebsiella pneumonia). At 20 h post-CLP all rats develop positive blood cultures. Serum levels of TNF are not reproducibly measurable in rats following CLP. Rats undergoing CLP have a 50-80% mortality with deaths usually occurring 24-72 h postinjury. Repetitive (twice daily x 6 d) i.p. injection of sublethal doses of recombinant human TNF-alpha (100 micrograms/kg) to rats undergoing CLP 1 d after the treatment period resulted in a significant reduction in mortality compared to control rats previously unexposed to rTNF (P less than 0.03). Animals treated with rTNF had no hypotension or hypothermia after CLP and regained normal food intake faster than control rats. 12 h after CLP the gene expression for manganous superoxide dismutase (MnSOD), an inducible mitochondrial metalloenzyme responsible for cellular resistance to injury from toxic reactive oxygen species, was higher in livers of rats treated with rTNF suggesting that the TNF treatment augmented expression of this protective enzyme. Unlike MnSOD, expression of the gene for copper-zinc SOD was not affected by CLP or rTNF treatment. The results suggest that prior treatment with recombinant TNF can ameliorate the lethality, hypotension, hypothermia, and anorexia of Gram-negative sepsis in rats and that the mechanism may be related to enhanced hepatic expression of the gene for MnSOD. Repeated administration of recombinant TNF may be a strategy to minimize mortality and morbidity of Gram-negative sepsis.

Animals↗