Biomedical subjects

R W Pero

Publications and source records attributed to R W Pero.

At least 37 records · Page 2Linked to original sources

PubMed1997

Comparative central nervous system effects and pharmacokinetics of neu-metoclopramide and metoclopramide in healthy volunteers.

Metoclopramide, a drug used for the relief of nausea and emesis, is currently under development as a radio- and chemosensitizing agent. Its usefulness in high doses, however, is limited by its central nervous system side effects. Neu-metoclopramide (Neu-Sensamide), a novel, concentrated, phosphate-buffered, pH-adjusted (pH = 6.5-7.0) formulation of metoclopramide, has been shown to have an improved side-effect profile in animal studies. The present double-blind, four-way crossover study compared the central nervous system effects and pharmacokinetics of neu-metoclopramide (intravenously and intramuscularly at 1.8 mg/kg) with intravenous metoclopramide and intramuscular placebo in 19 healthy male volunteers. Eight participants withdrew from the study, one because of noncompliance and seven because of adverse events. A total of 28 central nervous system events were observed with intravenous metoclopramide administration, whereas 16, 15, and 6 such events were attributed to intravenous neu-metoclopramide, intramuscular neu-metoclopramide, and placebo, respectively. Extra-pyramidal effects occurred on 10 occasions: 7 after intravenous metoclopramide, 2 after intravenous neu-metoclopramide, and 1 after intramuscular neu-metoclopramide. No significant differences were observed in the pharmacokinetic profiles of the three formulations of metoclopramide. It may be speculated, therefore, that the molecular conformational changes inherent to neu-metoclopramide result in a reduced side-effect profile compared with conventional metoclopramide formulations.

Adult↗

PubMed1997

Low serum thiol levels predict shorter times-to-death among HIV-infected injecting drug users.

OBJECTIVES: To investigate whether serum thiol levels are altered by HIV disease, and whether low serum thiols predict time to death among HIV-infected injecting drug users (IDU). DESIGN: A cross-sectional study of serum thiol levels among 13 HIV-seronegative IDU, 116 HIV-seropositive IDU, and 17 HIV-seropositive IDU with a history of AIDS, and a cohort study of the 133 HIV-infected IDU who took part in the cross-sectional study. METHODS: Subjects were recruited from a methadone-maintenance treatment program during 1990-1991. Total serum thiols were determined spectrophotometrically at enrolment; low serum thiols were defined as those with an absorbance at 412 nm < or = 0.46. Deaths through 31 December 1993 were determined from the National Death Index (NDI). Twenty-six HIV-seropositive subjects died during follow up; death certificates, which were obtained for 23 subjects, indicated AIDS or HIV infection for 20. Product-limit estimation was used to calculate survival. Multivariate analyses employed Cox proportional-hazards regression. RESULTS: Analysis of cross-sectional data showed that serum thiols did not differ significantly among HIV-free subjects, HIV-infected subjects, and HIV-infected subjects with a history of AIDS. Cohort analysis, adjusted for age, revealed that persons with those with high serum thiols (relative hazard = 2.83; 95% confidence interval (CI), 1.15, 6.97); a significant interaction between low serum thiols and a history of AIDS was associated with a relative hazard of 5.65 (95% CI, 1.22-2.61). CONCLUSIONS: Among HIV-infected persons, low serum thiols, especially in concert with a history of AIDS, predict mortality risk. These findings support the hypothesis that oxidative stress is critical to the pathogenesis of HIV infection.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Pharmacokinetics, toxicity, side effects, receptor affinities and in vitro radiosensitizing effects of the novel metoclopramide formulations, sensamide and neu-sensamide.

Metoclopramide is a drug which has experienced worldwide use in the clinic for over 30 years as an antiemetic. Recently, it has also been shown to possess radio- and chemosensitizing properties in both animal tumour models and humans at the higher dose of 2 mg/kg. Two new metoclopramide formulations are being clinically developed and they differ mainly in whether the pH of their formulations are acidic (pH 2.5-3.5) or neutral (pH 6.5-7.0). Here we report that intramuscular administration of neutral metoclopramide is about 100% bioavailable, safer and with reduced side effects compared to acidic metoclopramide delivered by intramuscular injection to rats within the dose range of 3.5 to 14 mg/kg. The intramuscular administration of metoclopramide was also about 100% bioavailable compared to the intravenous route of administration. Furthermore, neutral metoclopramide had significantly decreased affinity for dopamine D2 receptors and increased affinity for 5-hydroxytryptamine, receptors, but the radiosensitizing potency was the same, when compared to equimolar concentrations of acidic metoclopramide. Taken together these data support the continued development of neutral metoclopramide for high dose intramuscular administration of metoclopramide for future clinical use as both an antiemetic and radiosensitizer.

Animals↗

PubMed1997

Neutral metoclopramide induces tumor cytotoxicity and sensitizes ionizing radiation of a human lung adenocarcinoma and virus induced sarcoma in mice.

Radiation induced cytotoxicity was potentiated by neutralized metoclopramide (nMCA; Neu-Sensamide, Oxigene Inc) when a human lung adenocarcinoma (H2981) transplanted into scid mice and an adeno-type 12 virus induced mouse sarcoma (A12B3) inoculated into CBA mice were exposed in vivo to low dose radiation at single doses of 1 and 2 Gy respectively. However, when the radiation dose was increased to 6, 10 or 18 Gy (single dose) and combined with a single dose nMCA (2 mg/kg), tumor cytotoxicity was not sensitized by the combination treatment. A fractionated dose of ionizing radiation (3 x 1 Gy) in combination with nMCA at a repeated dose of 3 x 10 mg/kg body weight (1 dose/day, i.m.) significantly increased cytotoxicity in H2981 compared with radiation given alone. nMCA alone also had a statistically significant dose dependent cytotoxic effect on H2981 growth when it was administered as repeated doses (8 doses) at 2 mg/kg or 10 mg/kg (1 dose every second day), and a similar result was achieved at 20 mg/kg but not at 2 and 10 mg/kg in the A12B3 tumor. In addition, the tumor volume at the start of treatment was important for the anti-tumor effect of nMCA (i.e. the larger initial tumor volume gave less effect on tumor growth). Taken together, our data propose that the mode of action of nMCA is different from radiation, and hence the two mechanisms are at least additive when in combination with lower radiation doses. The data further suggest that the cytotoxic mechanism is consistent with potentiating apoptosis because low and repeated doses of radiation (1-2 Gy), which are known to increase cytotoxicity by apoptosis, are sensitized by nMCA but not high doses and nMCA has more potent anti-tumor effects against H2981 tumors which have a higher constitutive apoptotic fraction of cells than A12B3.

Adenocarcinoma↗

PubMed1997

Toxicity, antitumor and chemosensitizing effects of 3-chloroprocainamide.

3-Chloroprocainamide (3-CPA), an analog of metoclopramide (MCA), dose-dependently inhibited tumor growth in scid mice xenografted with a human brain astrocytoma (T24) when given intramuscularly to mice every third day for 14-20 days. 3-CPA was shown to have the same efficacy on tumor growth inhibition as neutral metoclopramide (neutral MCA) at the doses of 10-40 mg/kg when evaluated by tumor doubling time, tumor growth time for tumor volumes to reach 1000 mm3 and area under growth curve. 3-CPA at the dose of 3 x 40 mg/kg was also shown to enhance the cytotoxicity induced by a single dose of cisplatin at 7.5 mg/kg. A dose of < or = 160 mg/kg of 3-CPA did not show any notable extrapyramidal symptoms which was observed for neutral MCA treated mice at the dose of 20 mg/kg. The lethal response dose of 3-CPA for scid mice was 320 mg/kg which is 4 times higher than that determined for neutral MCA (80 mg/kg). These results support 3-CPA as a good candidate drug representing a new generation of benzamides for further clinical development as a cancer therapy drug.

Animals↗

PubMed1996

DNA damage and repair in tumour and non-tumour tissues of mice induced by nicotinamide.

In vivo DNA damage and repair was induced by nicotinamide (NAM) in adenotype 12 virus-induced mouse sarcoma A12B3 and sarcoma F inoculated into CBA mice. DNA damage, NAM and NAD concentrations were measured after in vivo exposure to NAM, in tumours and spleens by alkaline elution and by HPLC analysis. Our results indicate that NAM between 100-1000 mg kg-1 causes a high level of in vivo DNA strand breaks in tumours and normal tissues in mice bearing the immunogenic sarcoma A12B3 but not in the non-immunogenic sarcoma F. The repair process was also delayed by the NAM treatment probably owing to inhibition of the DNA repair enzyme, poly(ADP-ribose)polymerase, as evidenced by accumulation of NAM and NAD. These data are consistent with NAM having a mechanism of action as a radiosensitiser at least in part by DNA repair inhibition. In addition, it should also be considered that high doses of NAM might cause considerable complications to normal tissue in tumour-bearing individuals.

Animals↗

PubMed1996

Hypochlorous acid/N-chloramines are naturally produced DNA repair inhibitors.

Human mononuclear leukocytes (HML) respond to oxidative DNA damage by activation of ADP ribosylation and initiation of DNA repair synthesis (i.e. unscheduled DNA synthesis, UDS), whereas neutrophils do not. When neutrophils are added to HML cultures in ratios up to 4:1 ADP ribosylation becomes inhibited to approximately 50-60%. The ability of neutrophils to inhibit HML ADP ribosylation was shown to be dependent on H2O2, chloride ions and myeloperoxidase, which in turn are factors known to govern HOCl and N-chloramine production by phagocytic cells. HOCl and a model N-chloramine, chloramine T, were shown to give a dose-dependent inhibition of DNA repair using four independent estimates, namely ADP ribosylation, UDS and the repair of DNA strand breaks estimated by nucleoid sedimentation and alkaline elution profiles. All the DNA repair measurements used on HML were inhibited approximately 70-80% by 100 microM doses of HOCl or chloramine T, which was considered a biologically relevant dose because: (i) viable neutrophils equal in concentration to those found in blood could easily produce 100 microM levels in short-term culture; (ii) 100 microM doses of these agents were not acutely cytotoxic judged by trypan blue stained cells after 30-60 min exposure and under the conditions used for assay, but yet they abolished 86-95% of the growth response of HML to phytohemagglutinin.

Adenosine Diphosphate Ribose↗

PubMed1996

Psychogenic stress induces chromosomal and DNA damage.

In this investigation, rats subjected to swim stress showed within 24 hours significant increases in both the level of chromosome aberrations and Sister Chromatid Exchanges (SCEs) in bone marrow cells. The generality of cytogenetic damage by behavioral stressors was demonstrated by exposing rats to both cold-and warm-water forced swims, to white noise, and to continuous or intermittent inescapable foot shock stress (IFS). The induction of chromosome aberrations and SCEs, to differing degrees, by stressors that differ both quantitatively and qualitatively, demonstrates that this is a general phenomenon of stress. The use of an additional measure, unscheduled DNA Synthesis (UDS) showed that stress-induced genotoxic damage can occur in a second cell type and on a molecular as well as chromosomal level. These results indicate that there may be a cellular genetic basis for some of the effects of stress.

Animals↗

PubMed1995

Progress in identifying clinical relevance of inhibition, stimulation and measurements of poly ADP-ribosylation.

Our laboratory, in collaboration with Oxigene Inc, has been involved in identifying commercially feasible clinical applications of measurement or modulation of ADP-ribosylation as a core technology. For this purpose a pivotal regulatory role for ADP-ribosylation in the repair of DNA lesions leading to cytotoxic as well as mutagenic events has been hypothesized. A new class of DNA repair inhibitors, the N-substituted benzamides, has been identified which can react with radiation to produce reactive intermediates that oxidize thiol amino acids. Their proposed mechanisms of action are two-fold: ie they can interact with radiation: i) to directly enhance DNA damage; and ii) to react with thiols in the zinc finger DNA binding domain of poly ADP-ribosyl transferase to inhibit DNA repair and thereby increase DNA damage. Sensamide, a clinically relevant formulation of metoclopramide which is an N-substituted benzamide, has indicated enhancement of tumor response and survival in patients with inoperable squamous cell carcinoma of the lung when it was administered as a radiosensitizer in a phase I/II trial and compared to historical controls. A mechanism of endogenous regulation of human mononuclear leucocyte ADP-ribosylation has been identified to be HOCl/N-chloramine production via the oxidative burst of phagocytes. HOCl/N-chloramines are potent oxidants of thiol-containing proteins. Quantitative estimation of N-chloramine sensitive plasma thiols has been identified as an effective surrogate measure of leucocyte poly ADPRT.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

A phase I/II evaluation of metoclopramide as a radiosensitiser in patients with inoperable squamous cell carcinoma of the lung.

The feasibility of administering metoclopramide (MCA) as a radiosensitizer has been evaluated in 23 patients with a pathological or cytological diagnosis of a squamous cell carcinoma of the lung, clinically evaluated as inoperable. All patients received 40-60 Gy radiotherapy fractionated into 1.8 Gy fractions 5 times per week (Monday-Friday). Two MCA treatment regimens were used: (i) MCA at 2 mg/kg administered by intravenous-infusion 1-2 h prior to radiotherapy 3 times per week (Monday, Wednesday, Friday); and (ii) MCA at 1 mg/kg administered by intravenous infusion 1-2 h prior to radiotherapy 5 times per week (Monday-Friday). 11 of the 23 patients treated with radiotherapy and MCA had none to mild pneumonitis or fibrosis and another 8 of the 23 had moderate levels. No patient had their therapy interrupted due to radiation-related side-effects. The MCA-related side-effects were as expected, i.e. 78% of the patients experienced sedation/tiredness and 48% expressed restlessness/anxiety symptoms. Both the total dose and serum levels of MCA were significantly associated to the MCA side-effect profile. Tumour response, duration of tumour response and survival were significantly positively correlated to the total and weekly doses of MCA administered to the patients during their radiotherapy treatment. These favourable phase II data have justified the initiation of a phase II/III randomised multicentred trial being carried out in Europe to evaluate MCA as a radiosensitiser.

Aged↗

PubMed1995

In vivo tumor measurement of DNA damage, DNA repair and NAD pools as indicators of radiosensitization by metoclopramide.

Metoclopramide (MCA), a N-substituted benzamide, causes DNA strand breaks and inhibits DNA repair in vitro and sensitizes radiation and chemotherapeutic drugs in human squamous cell carcinomas when xenographed into nude mice or in a rat glioma model. Here we report on the evaluation of the mechanism behind the radiosensitizing effects of MCA. DNA damage was measured in vivo in a CBA-mouse tumor line (A12B3, sarcoma tumor) by using both alkaline elution and nucleoid sedimentation analysis of cell suspensions prepared from either resected tumor, spleen tissues or whole blood samples. The amount of DNA damage caused by radiation alone, measured 30 min after the irradiation was started, was dose dependent up to 18 Gy in all tissues. The radiation-induced DNA damage in tumor tissue was elevated compared to radiation alone in the presence of MCA, but the level was not higher at 18 Gy compared to 6 Gy in the presence of MCA, and it was still not fully repaired 12 h after irradiation. HPLC analysis of the NAD pools in tumor tissue after DNA damage induction showed a delay in the recovery of the NAD pools (presumably due to the presence of still unrepaired DNA) after exposure to MCA (2 mg/kg) + radiation (6 Gy) compared to tumors exposed to radiation (6 Gy) only, which were fully restored after 48 h. These data confirm earlier published in vitro data on MCA as an inducer of DNA damage and an effector of DNA repair. In addition, the in vivo measurement of radiation-induced DNA damage and DNA repair using the nucleoid sedimentation and alkaline elution assays together with NAD pool determinations may prove to be effective intermediate endpoints in the evaluation of drugs as potential radiosensitizers.

Animals↗

PubMed1995

Acidic and neutralized metoclopramide formulations sensitize ionizing radiation induced cytotoxicity in a human lung adenocarcinoma xenografted to scid mice.

A neutralized formulation (Neu-Sensamide) of metoclopramide (MCA) has been shown to possess reduced sedative side effects compared with the conventional acidic formulations (Primperan). The acidic formulation of MCA has also been shown to sensitize the effect of ionizing radiation (6-8 Gy) using human squamous cell carcinomas from the head and neck xenografted to nude mice. In the present study, 2 mg MCA/kg body weight 1-3 h before treatment with 1 Gy radiation (single dose) was evaluated in scid mice xenografted with a human lung adenocarcinoma. MCA given alone in acidic or neutralized formulations did not show any effect on tumor growth retardation. However, when combined with radiation, both acidic and neutralized formulations of MCA sensitized the cytotoxic effect of radiation directed against the tumors by increasing tumor doubling time, tumor quadrupling time and specific growth delay, and by decreasing area under growth curve measurements. In addition, there was no statistically significant difference between the two formulations of MCA in the efficacy of sensitizing the cytotoxicity of a single low dose (1 Gy) of radiation.

Adenocarcinoma↗

PubMed1994

Non-specific steroidal esterase activity and distribution in human and other mammalian tissues.

An NADPH dependent arylamine carcinogen and fatty acid steroid ester metabolizing esterase activity belonging to the B- or carboxylesterase class of non-specific esterase (EC 3.1.1.1) was measured by two different methods: (i) a spectrophotometric assay using alpha naphthyl acetate (ANA) as substrate and (ii) a radiometric method using the conversion of beclomethasone-17,21-dipropionate to beclomethasone-17-monopropionate as the endpoint. The two methods were strongly correlated when assayed in human mononuclear leukocytes (r = 0.89, P < 0.0001) and human mammary tissue (r = 0.91, P < 0.0001). Hence it was concluded that the two substrates are metabolized at least in part by the same enzyme. This esterase activity was abundant in human monocytes, present in T-lymphocytes and equally divided between CD4 and CD8 T-lymphocyte subsets. The same activity was expressed in human liver, colon, stomach, breast and brain tissues. The distribution of this esterase in human tissues showed high activity in liver, intermediate activity in colon, stomach and breast and low activity in brain tissue. The interorgan distribution observed in human tissues was closely mimicked when the esterase activity was assessed in liver, colon and brain tissues from three mouse strains and three rat strains. The non-specific steroidal esterase activity determined by ANA metabolism in human mammary tissue was shown to be reproducible when assayed as triplicate samples from each of 16 different women (intraclass correlation coefficient 67.3%, P < 0.03). The interindividual variation in mammary tissue was high (18.4-fold) and there was a positive correlation between the esterase activity and age (r = 0.58, P < 0.01), as well as a tendency toward bimodal distribution. To our knowledge, these data represent the first systematic study of interorgan and interspecies comparisons of a non-specific steroidal esterase activity.

Adult↗

PubMed1994

Chlorpromazine in combination with nitrosourea inhibits experimental glioma growth.

Modern cancer therapy has improved the prognosis for several tumour types. This, however, does not apply to the largest group of brain tumours, the malignant astrocytomas grades III-IV. Hence, there is need for new ideas to improve treatment. Ca2+ and the Ca(2+)-binding protein calmodulin have been shown to be involved in the processes conferring stability to DNA in proliferating neoplastic cells. We have combined the calmodulin-inhibiting neuroleptic drug chlorpromazine (CPZ), with the anti-neoplastic drug 1,3-bis(2-chloroethyl-1)-nitrosourea (BCNU) in a treatment regime for rats with glioma cells implanted in the brain. A highly significant inhibiting effect upon the tumour growth was noticed, not by CPZ or BCNU as single drugs, but with their combination.

Animals↗

PubMed1993

Specific binding and uptake of extracellular nicotinamide in human leukemic K-562 cells.

Extracellular nicotinamide is well recognized as the primary precursor to the cellular synthesis of NAD. NAD is a pivotal molecule in regulating the energy and redox potentials of cells via synthesis of ATP and NAD(P)/NAD(P)H ratios. NAD turnover in cells is very rapid due to NAD catabolism via ADP-ribosylation reactions. These facts suggest that the cellular uptake and transport of nicotinamide may not be a passive process but a highly regulated cellular event. We have utilized radiometric procedures to characterize the uptake of [14C]nicotinamide in human leukemic K-562 cells. At physiologically relevant doses of nicotinamide (< 100 microM), the uptake was saturable with a Km of 2.3 +/- 1.0 microM and a Vmax of about 1.5 +/- 0.5 pmol/10(6) cells/min. Kinetic studies revealed that nicotinamide was first taken up intracellularly and then immediately converted to NAD and 1-methyl nicotinamide. All of the nicotinamide taken up into the cell was bound tightly to plasma membranes (25,000 g pellet) with Kd values between 3.2 and 12.7 microM and a Bmax of 1.56 pmol/10(6) cells. The specificity of nicotinamide binding was demonstrated by competitive inhibition experiments using NAD analogs, nicotinamide derivatives, and agonists or antagonists of plasma membrane receptors. We conclude that there is specific binding of nicotinamide, followed by intracellular uptake and immediate synthesis to NAD.

Binding, Competitive↗

PubMed1993

The Malmö biological bank.

Currently there are no available biological markers that have been satisfactorily validated clinically as 'intermediate end-points' for evaluation of the impact of diet on cancer. Therefore, there is high scientific value in banking biological specimens for future use in the Malmö Diet and Cancer Study. The banking procedures we have developed are adequate for assessing factors that estimate dietary intake (e.g. vitamins, lipids or micronutrients) as well as non-dietary variables (e.g. immunologic and ecogenetic factors of biologically effective doses of xenobiotic exposures) that may regulate the biological expression of dietary variables. This approach is further justified by state-of-the-art technology that includes assessment of the concept of gene-environment interactions. Purified viable mononuclear leucocytes, granulocytes, erythrocytes, plasma and serum are being stored from each individual entering the study under the guidelines of a strict quality control programme. Storage of tumour/normal tissues from incident cancer cases are also being stored and quality controlled. It is hoped that these banking procedures will encourage a high activity in biomarker development in the future.

Algorithms↗

PubMed1993

The Malmö biomarker programme.

Evaluation of pro-oxidant/antioxidant dietary factors in relation to individual susceptibility to cancer and cardiovascular disease is justified based on a review of the literature. This working hypothesis is amendable to further scientific validation from biomarkers with end-point sensitivity to oxygen radicals. So far, the biomarker programme developed around this theme may be divided into three distinct classes: (1) Markers of genotoxic exposure estimate DNA damage either directly as a biologically effective dose, or indirectly by estimating aberrant cellular functions that lead to accumulation of DNA damage. The examples included are ADP-ribosylation in mononuclear leucocytes (R. Pero, A. Olsson), oxidative DNA damage (K. Frenkel), gene expression in lymphocytes (S. Garte, G. Cosma), serum alpha macroglobulin (W. Troll) and oxidized DNA damage and repair (N. Christie). (2) Markers of genetic predisposition have been shown to have genetic inheritance patterns that relate to individual susceptibility to cancer or cardiovascular disease. The examples included are glutathione transferase mu phenotyping (R. Pero, J. Seidegård) and poly (ADP-ribose) polymerase pseudogene polymorphism (M. Smulson). (3) Markers of dietary status have been validated to estimate the amount of a particular nutrient or xenobiotic in the diet that has been taken up and metabolized or distributed to body fluids or tissues. The example included here is niacin nutriture (E. Jacobson, M. Jacobson). This biomarker is presented in Section 5 (pp. 59-62) of the Malmö Diet and Cancer Programme Minisymposium reported in this issue of the journal.

Animals↗

PubMed1992

Steroidal nonspecific esterase metabolism of N-hydroxy-2-acetylaminofluorene: evidence for selective activation by the cellular reductant NADPH.

The significance of the nonspecific esterases of human mononuclear leukocytes (HMLs) in arylamine carcinogenesis is suggested by data showing that the metabolically formed hydroxamic acid derivative of 2-acetylaminofluorene, N-hydroxy-2-acetylaminofluorene, is a substrate for this class of enzymes. A viable cell assay for the nonspecific esterases using alpha-naphthyl acetate as substrate is described, and data showing this activity to be sensitive to already known substrates for HML esterases as measured by three previously described assays are presented. All four assays of the same esterase activity are shown to be highly sensitive to up- and down-regulation by addition of NADPH or NADP to viable HML cultures. Selective activation of a purified rabbit nonspecific esterase by NADPH, but not by the other cellular reductants, NADH and glutathione, was demonstrated. Cytosols prepared from normal human tissue samples of liver, breast, colon, and brain were also activated by the presence of NADPH. These data do not indicate that steroidal nonspecific esterases are redox-modulated by the presence of mixed disulfides in their structure. Instead, they support the direct and specific influence of NADPH as a widespread activator of esterase activity by a mechanism not yet understood.

Animals↗