Artemisinin-derived sesquiterpene lactones as potential antitumour compounds: cytotoxic action against bone marrow and tumour cells

Epidemiologic and public health researchers frequently include several dependent variables, repeated assessments, or subgroup analyses in their investigations. These factors result in multiple tests of statistical significance and may produce type 1 experimental errors. This study examined the type 1 error rate in a sample of public health and epidemiologic research. A total of 173 articles chosen at random from 1996 issues of the American Journal of Public Health and the American Journal of Epidemiology were examined to determine the incidence of type 1 errors. Three different methods of computing type 1 error rates were used: experiment-wise error rate, error rate per experiment, and percent error rate. The results indicate a type 1 error rate substantially higher than the traditionally assumed level of 5% (p < 0.05). No practical or statistically significant difference was found between type 1 error rates across the two journals. Methods to determine and correct type 1 errors should be reported in epidemiologic and public health research investigations that include multiple statistical tests.     

Immunization with E. coli produced recombinant T. gondii SAG1 with alum as adjuvant protect mice against lethal infection with Toxoplasma gondii

Polyclonal rabbit antibodies against recombinant Toxoplasma gondii SAG1 antigen expressed in E.coli recognize T. gondii and the antibodies significantly reduced T.gondii adherence and/or invasion into the host cell as did a monoclonal antibody against a conformational epitope of the SAG1 antigen. Groups of outbread NMRI mice were immunized with recombinant T. gondii SAG1 antigen in alum. The antibody response to immunizations was dominated by a Th2 response with production of T.gondii specific IgG1 antibodies. Challenge with tachyzoites from the virulent RH-strain produced a Th1 response dominated by the production of specific IgG2a antibodies and moderately boosted the IgG1 response, and challenge with bradyzoites from the avirulent SSI119-strain showed the same pattern. Immunization with rSAG1 resulted in a significant increased survival after challenge with tachyzoites of the RH-strain. Immunization with E.coli expressed recombinant SAG1 in alum induce partial protective immunity against lethal infection with T. gondii in mice.     

Infection of sheep with adult and larval Ostertagia circumcincta: abomasal morphology

The infection of parasite-naive sheep with approximately 15,000 adult Ostertagia circumcincta via abomasal cannulae resulted in marked changes in the structure and function of the abomasum. The functional changes, which have been characterised previously, included elevated abomasal pH and increased serum concentrations of pepsinogen and gastrin. Eight days after the transplant of adult worms, the abomasa of recipient animals were significantly heavier than those of controls (P < 0.001), the thickness of the fundic mucosa was greater (P < 0.01), there were fewer parietal cells (P < 0.01) and increases in the numbers of mitotic figures and mucus-producing cells. Mucous cell hyperplasia was also evident in the fundic mucosae of sheep receiving a trickle infection of infective, third-stage O. circumcincta larvae and was prominent within nodules associated with larval development. In non-nodular mucosa, there was hyperplasia of mucous cells and changes in the distribution of parietal cells. Decreases in the number of parietal cells at the gland base were offset by increases at a mid-gland level, probably due to chronic hypergastrinaemia, so that, overall, total parietal cell number was unaffected. Mucous cell hyperplasia and the diminution of parietal cell number are seen in a diverse range of disease states and may be mediated by host growth factors such as Transforming growth factor-alpha. Alternatively, the cellular and/or the secretory changes in response to the presence of adult worms are mediated by chemicals that are cytotoxic/inhibitory for parietal cells, and released by the parasites themselves.     

Distortions in infant electrocardiograms caused by inadequate high-frequency response

Frank lead ECG's from infants were studied for frequency content by introducing low-pass filters of 50, 75, 100, and 150 150 Hz bandwidths before obtaining computer measurements. Results indicated that a minimum bandwidth of 100 Hz is required to avoid amplitude error of 10 per cent or greater. This bandwidth requierement is essentially the same as that required for adult ECG's despite the fact that infant QRS durations are usually about half those of adults. Although the average infant ECG spectrum is likely to contain higher frequencies than the average adult ECG spectrum, duration values for Q, R, and S waves overlap in these populations to such an extent that bandwidth requirements are practically identical.     

Poliomyelitis outbreak in Israel, 1950-1

The epidemicity of poliomyelitis in Israel since 1950 is reviewed, and the influence of the mass immigration which took place between 1948 and 1952 is discussed. Age distribution and attack-rates among Arabs, among Jewish population-groups originating in different countries, and among old residents and new immigrants, are examined. It is suggested that the change from endemicity to epidemicity of the disease may have been due to general overcrowding during the pre-epidemic period, and to enhanced circulation of virus (type 1), and a resulting increase in its pathogenicity.     

Placental villous stroma as a model system for myofibroblast differentiation

Different subtypes of myofibroblasts have been described according to their cytoskeletal protein patterns. It is quite likely that these different subtypes represent distinct steps of differentiation. We propose the human placental stem villi as a particularly suitable model to study this differentiation process. During the course of pregnancy, different types of placental villi develop by differentiation of the mesenchymal stroma surrounding the fetal blood vessels. In order to characterise the differentiation of placental stromal cells in the human placenta, the expression patterns of the cytoskeletal proteins vimentin, desmin, alpha- and gamma-smooth muscle actin, pan-actin, smooth muscle myosin, and the monoclonal antibody GB 42, a marker of myofibroblasts, were investigated on placental tissue of different gestational age (7th-40th week of gestation). Proliferation patterns were assessed with the proliferation markers MIB 1 and PCNA. Additionally, dipeptidyl peptidase IV distribution was studied in term placenta and the ultrastructure of placental stromal cells was assessed by electron microscopy. Different subpopulations of extravascular stromal cells were distinguished according to typical co-expression patterns of cytoskeletal proteins. Around the fetal stem vessels in term placental villi they were arranged as concentric layers with increasing stage of differentiation. A variable layer of extravascular stromal cells lying beneath the trophoblast expressed vimentin (V) or vimentin and desmin (VD). They were mitotically active. The next layer co-expressed vimentin, desmin, and alpha-smooth muscle actin (VDA). More centrally towards the fetal vessels, extravascular stromal cells co-expressed vimentin, desmin, alpha- and gamma-smooth muscle actin, and GB 42 (VDAG). Cells close to the fetal vessels additionally co-expressed smooth muscle myosin (VDAGM). Ultrastructurally, V cells resembled typical mesenchymal cells. VD cells corresponded to fibroblasts, while VDA and VDAG cells developed features of myofibroblasts. Cells of the VDAGM-type revealed a smooth muscle cell-related ultrastructure. In earlier stages of pregnancy, stromal cell types with less complex expression patterns prevailed. The media smooth muscle cells of the fetal vessels showed a mixture of different co-expression patterns. These cells were separated from extravascular stromal cells by a layer of collagen fibres. The results obtained indicate a clearly defined spatial differentiation gradient with increasing cytoskeletal complexity in human placental stromal cells from the superficial trophoblast towards the blood vessels in the centre of the stem villi. The spatial distribution of the various stages of differentiation suggests that human placental villi could be a useful model for the study of the differentiation of myofibroblasts.     

Immunohistochemistry of matrix metalloproteinases (MMP), their substrates, and their inhibitors (TIMP) during trophoblast invasion in the human placenta

The invasion of extravillous trophoblast cells into the maternal endometrium is one of the key events in human placentation. The ability of these cells to infiltrate the uterine wall and to anchor the placenta to it as well as their ability to infiltrate and to adjust utero-placental vessels to pregnancy depends, among other things, on their ability to secrete enzymes that degrade the extracellular matrix. Most of the latter enzymes belong to the family of matrix metalloproteinases. Their activity is regulated by the tissue inhibitors of matrix metalloproteinases. We have studied the distribution patterns of matrix metalloproteinases-1, -2, -3, and -9 and their inhibitors TIMP-1 and TIMP-2 as compared to the distribution of their substrates along the invasive pathway of extravillous trophoblast of 1st, 2nd, and 3rd trimester placentas by means of light microscopy on paraffin and cryostat sections as well as at the ultrastructural level (only 3rd trimester placenta). The comparison of different methods proved to be necessary, since the immunohistochemical distribution patterns of these soluble enzymes are considerably influenced by the pretreatment of tissues. All three methods revealed immunoreactivities of both, proteinases and their inhibitors, not only intracellularly in the extravillous trophoblast but also extracellularly in its surrounding matrix, the distribution patterns depending on the stage of pregnancy and on the degree of differentiation of trophoblast cells along their invasive pathway. Within the extracellular matrix, immunolocalization of matrix metalloproteinases as well as their inhibitors showed a specific relation to certain extracellular matrix molecules.     

Crystal structure of farnesyl protein transferase complexed with a CaaX peptide and farnesyl diphosphate analogue

The crystallographic structure of acetyl-Cys-Val-Ile-selenoMet-COOH and alpha-hydroxyfarnesylphosphonic acid (alphaHFP) complexed with rat farnesyl protein transferase (FPT) (space group P61, a = b = 174. 13 A, c = 69.71 A, alpha = beta = 90 degrees, gamma = 120 degrees, Rfactor = 21.8%, Rfree = 29.2%, 2.5 A resolution) is reported. In the ternary complex, the bound substrates are within van der Waals contact of each other and the FPT enzyme. alphaHFP binds in an extended conformation in the active-site cavity where positively charged side chains and solvent molecules interact with the phosphate moiety and aromatic side chains pack adjacent to the isoprenoid chain. The backbone of the bound CaaX peptide adopts an extended conformation, and the side chains interact with both FPT and alphaHFP. The cysteine sulfur of the bound peptide coordinates the active-site zinc. Overall, peptide binding and recognition appear to be dominated by side-chain interactions. Comparison of the structures of the ternary complex and unliganded FPT [Park, H., Boduluri, S., Moomaw, J., Casey, P., and Beese, L. (1997) Science 275, 1800-1804] shows that major rearrangements of several active site side chains occur upon substrate binding.