Effect of intravenous infusions of 12-O-tetradecanoylphorbol-13-acetate (TPA) in patients with myelocytic leukemia: preliminary studies on therapeutic efficacy and toxicity

Studies by several investigators have shown that 12-0-tetradecanoylphorbol-13-acetate (TPA) is an extraordinarily potent stimulator of differentiation of cultured human promyelocytic leukemia cells in vitro. In the present study, TPA was administered to humans by i.v. infusion without irreversible toxicity, and it was shown to have pharmacological activity for the treatment of myelocytic leukemia in patients refractory to cytosine arabinoside (Ara C), retinoic acid, and other antileukemic drugs. Marked decreases in bone marrow myeloblasts as well as temporary remission of disease symptoms were observed when TPA was administered alone or in combination with vitamin D3 and Ara C. Additional studies with TPA after the determination of optimum dosing regimens are needed to determine whether long-lasting or permanent remissions of myelocytic leukemia can be achieved. Transient and reversible side effects were observed after a 1-mg i.v. dose of TPA, but these adverse effects became less intense or disappeared when a lower dose of TPA was used. The results of this study indicate a therapeutic effect of TPA in patients with myelocytic leukemia.     

Seroprevalence of porcine reproductive and respiratory syndrome virus in Dutch weaning pigs

To determine whether under Dutch field conditions PRRSV infection occurs in weaning pigs before the finishing period, a cross-sectional study was performed on 32 breeding farms to estimate the seroprevalence of antibodies directed against PRRSV in 4- to 5-week-old and 8- to 9-week-old pigs. Farms were visited twice within 5 months, and during each sampling an average of 20 sera were randomly collected from a unit of 4- to 5-week-old and a unit of 8- to 9-week-old pigs. The sera (n = 2568) were tested in the IDEXX-ELISA for the presence of antibodies directed against PRRSV. The seroprevalence of PRRSV in 4- to 5-week-old pigs and 8- to 9-week-old pigs varied between both samplings for each farm. The seroprevalence in the younger pigs was significantly higher than in the older pigs for both samplings (p < 0.05), suggesting the presence of maternal antibodies. In addition, a longitudinal study was performed to evaluate the IDEXX-ELISA in detecting maternal antibodies directed against PRRSV and to determine the rate of decline of these antibodies in field sera. From serological results of eight litters, an average decay function was computed to quantify the maternal immunity to PRRSV. A seroprevalence in 8- to 9-weeks-old pigs of > or = 0.20 was calculated to indicate an active immune response to PRRSV. In the cross-sectional study in the pigs twenty-three percent of the units with 8- to 9-week-old pigs were considered to have an active serological response against PRRSV. We conclude that most Dutch pigs are seronegative for PRRSV at the start of the finishing period, since the results of this study showed that 77% of the units with 8- to 9-week-old pigs had a seroprevalence < 0.20.     

The human Arp2/3 complex is composed of evolutionarily conserved subunits and is localized to cellular regions of dynamic actin filament assembly

People with epilepsy often encounter discrimination. Some cultures have established prohibitive laws limiting access to employment, restricting marriage, and denying driving privileges. It is not enough to repeal such laws. Legislation, such as the Americans with Disabilities Act (ADA), is needed to provide protections against discriminatory practices. The definitions and standards of the law provide clear guidance to employers and workers with disabilities regarding their rights and responsibilities in the workplace. The ADA is proving to be an effective means of addressing allegations of employment discrimination brought forward by people with seizure disorders, although it has not increased the number of people with disabilities who are employed. However, in combination with rehabilitation counseling and employer education, legislative protection can assist people with epilepsy to be more successful in their pursuit of employment opportunities.     

p53 Deficiency in liver reduces local control of survival and proliferation, but does not affect apoptosis after DNA damage

Despite good evidence for p53 dysfunction in human hepatocellular carcinomas, little is known of the significance of p53 to normal hepatocytes and whether p53 dysfunction is relevant to early hepatocarcinogenesis. We have therefore examined the consequences of targeted p53 deficiency in hepatocytes for regulation of apoptosis, proliferation, and ploidy. p53 deficiency was silent in normal liver and did not affect progression from diploidy to polyploidy in the aging liver. However, in primary culture the absence of p53 resulted in increased hepatocyte proliferation indices and decreased sensitivity to proliferation inhibition by TGFbeta. Moreover, p53-deficient cells continued to survive and proliferate under conditions of minimal trophic support that led to growth arrest and apoptosis of wild-type cells. In vivo, p53-deficient mice had enhanced proliferative responses to both xenobiotic hepatomitogen and CCl4-induced liver necrosis, although lack of persistent proliferation showed that other control mechanisms are important. There was no simple relationship between p53 and apoptosis after DNA damage because UV irradiation led to p53-independent apoptosis, even though p53 was stabilized. However, p53 did couple DNA damage to growth arrest, and abnormal mitoses after gamma-irradiation of regenerating p53 null livers demonstrated circumstances where loss of G1 and G2 checkpoints may generate abnormal ploidy. Thus p53 becomes important when hepatocytes are released from G0 and stressed, sensitizing them to mitogen and cytokine regulators of cell cycle progression and apoptosis. Hence p53 deficiency is likely to be significant in an environment of persistent regenerative stimuli and unfavorable trophic support or in the presence of other enabling genetic lesions. This model is relevant to human hepatocarcinogenesis, which almost always occurs against a background of chronic hepatocellular destruction in hepatitis and cirrhosis. In that context, by reducing the need for cytokine support and disabling DNA damage-induced growth arrest, p53 deficiency should facilitate the expansion of preneoplastic clones in chronic liver disease.     

Heterozygosity for a point mutation in an invariant splice donor site of dihydropyrimidine dehydrogenase and severe 5-fluorouracil related toxicity

Dihydropyrimidine dehydrogenase (DPD) is responsible for the breakdown of the widely used antineoplastic agent 5-fluorouracil (5-FU), thereby limiting the efficacy of the therapy. It has been suggested that patients suffering from 5-FU toxicities due to a low activity of DPD are genotypically heterozygous for a mutant allele of the gene encoding DPD. In this study we investigated the cDNA and a genomic region of the DPD gene of a cancer patient experiencing severe toxicity following 5-FU treatment for the presence of mutations. Although normal activity of DPD was observed in fibroblasts, the DPD activity in leucocytes of the cancer patient proved to be in the heterozygous range. Analysis of the DPD cDNA showed heterozygosity for a 165bp deletion that results from exon skipping. Sequence analysis of the genomic region encompassing the skipped exon showed that the tumour patient was heterozygous for a G-->A point mutation in the invariant GT splice donor sequence in the intron downstream of the skipped exon. So far, the G-->A point mutation has also been found in 8 out of 11 patients suffering from a complete deficiency of DPD. Considering the frequent use of 5-FU in the treatment of cancer patients, the severe 5-FU-related toxicities in patients with a low activity of DPD and the high frequency of the G-->A mutation in DPD deficient patients, analysis of the DPD activity and screening for the G-->A mutation should be routinely carried out prior to the start of the treatment with 5-FU.     

Use of the international prognostic index and the tumor score to detect poor-risk patients with primary mediastinal large B-cell lymphoma: a study of 37 previously untreated patients

How can enzymes function in the centre of a crowded lens over the many decades of an individual's life when the same proteins are usually turned over in a period of days or h in most other tissues? The discovery that alpha-crystallin could function as a molecular chaperone in-vitro has led to the hypothesis that alpha-crystallin could protect enzyme activities against various stresses. In the laboratory the authors have focused on the effect of alpha-crystallin on the activity of enzymes upon exposure to a chemical or thermal stress. The authors have demonstrated that enzymes are rapidly inactivated by sugars, sugar phosphates, steroids and cyanate. These compounds are elevated in diseases such as diabetes, diarrhoea and renal failure, all of which are risk factors for cataract. alpha-Crystallin has been shown to protect specifically against both chemically- and thermally-induced inactivation. Some enzymes are protected with a stoichiometry of one or two enzyme molecules protected per alpha-crystallin aggregate, consistent with a chaperone-like structure. However with other enzymes a more efficient protection occurs consistent with a micellar structure or binding on the outside of alpha-crystallin molecules. Investigation of complex formation indicates that although stable complex formation between enzymes and alpha-crystallin may be involved in protection of enzymes against thermal inactivation, protection against chemically-induced inactivation may be more dynamic in nature.     

IL-1/IL-3 gene therapy of non-small cell lung cancer (NSCLC) in rats using 'cracked' adenoproducer cells

Cytokine gene therapy was studied in established L42 tumours in syngeneic rats. L42 is a transplantable non-immunogenic non-small cell lung cancer (NSCLC). Genes coding for human interleukin-1 alpha and for rat interleukin-3 beta were transferred by injecting producer cells of recombinant adenovirus vectors into the tumour in attempts to achieve high concentrations of the cytokines inside the tumor without systemic toxicity. Limited tumour growth delay was obtained with viable producer cells. For logistic reasons stocks of pooled frozen producer cells allowed intensive treatment of groups of tumour bearing rats. The cells were lysed by thawing before administration. Ten daily injections of such 'cracked' producer cells induced reproducible tumour responses. These were due to local release of cytokines, not to systemic effects. Growth retardation also occurred in contralateral tumours which were not injected. When rats carrying established tumours were vaccinated with lysates of tumours collected during treatment with 'cracked' producer cells, significant tumour growth retardation was obtained. We speculate that both cytokines, if produced at sufficiently high concentrations in tumours, induce inflammation which in turn initiates an immune response against tumours growing at a distant site. These findings seem to justify further exploration of IL-1 and IL-3 gene transfer for the treatment of cancers.     

Effects of margarine compared with those of butter on blood lipid profiles related to cardiovascular disease risk factors in normolipemic adults fed controlled diets

Effects of butter and 2 types of margarine on blood lipid and lipoprotein concentrations were compared in a controlled diet study with 23 men and 23 women. Table spreads, added to a common basal diet, provided 8.3% of energy as fat. Diets averaged 34.6% of energy as fat and 15.5% as protein. Each diet was fed for 5 wk in a 3 x 3 Latin-square design. One margarine (TFA-M) approximated the average trans monoene content of trans fatty acid-containing margarines in the United States (17% trans fatty acids by dry wt). The other margarine (PUFA-M) was free of trans unsaturated fatty acids; it contained approximately twice the polyunsaturated fatty acid content of TFA-M (49% compared with 27% polyunsaturated fatty acids). The tub-type margarines had similar physical properties at ambient temperature. Fasting blood lipids and lipoproteins were determined in 2 samples taken from the subjects during the fifth week of each dietary treatment. Compared with butter, total cholesterol was 3.5% lower (P=0.009) after consumption of TFA-M and 5.4% lower (P< 0.001) after consumption of PUFA-M. Similarly, LDL cholesterol was 4.9% lower (P=0.005) and 6.7% lower (P< 0.001) after consumption of TFA-M and PUFA-M, respectively. Neither margarine differed from butter in its effect on HDL cholesterol or triacylglycerols. Thus, consumption of TFA-M or PUFA-M improved blood lipid profiles for the major lipoproteins associated with cardiovascular risk when compared with butter, with a greater improvement with PUFA-M than with TFA-M.