Hydrogen MR imaging of the head at 0.35 T and 0.7 T: effects of magnetic field strength

To determine whether hydrogen magnetic resonance imaging at 0.7 T provides added clinical value over imaging at 0.35 T, images of the heads of patients with various intracranial disorders were obtained at these field strengths. Measurements of tissue contrast (C), signal-to-noise (S/N) ratio, and T1 and T2 relaxation times were determined. For a given spin-echo sequence with equal imaging time, resolution, and data sampling window, the product C X S/N was somewhat lower for the lower field strength. Under conditions of imaging with equal chemical shift artifact, C X S/N at 0.35 T was equal to or greater than that measured at 0.7 T. With an increase in field strength, T1 of pathologic areas and surrounding normal tissues increased, resulting in a corresponding loss of absolute signal level and decrease in contrast. Lesions were equally well seen at both 0.35 T and 0.7 T. The increased T1 and decreased C X S/N for higher magnetic fields--when measured with a fixed imaging time, resolution, chemical shift, and sequence--suggest that such field strengths may not improve tissue contrast, diagnostic ability, or clinical throughput when compared with lower field strength systems.     

The effects of allopurinol in hepatic ischemia and reperfusion: experimental study in rats

BACKGROUND/AIMS: Some studies have shown that postischemic hepatic dysfunction is mainly due to oxygen free radicals that are generated by xanthine oxidase. The present study was undertaken to determine the effect of allopurinol, an inhibitor of xanthine oxidase, on oxidative stress, liver injury and histologic alterations induced by hepatic ischemia-reperfusion in rats. METHODS: One hundred and sixty Wistar rats were used and divided into three groups. Group 1: sham operation; group 2: 50 min of ischemia followed by 1 h of reperfusion, and group 3: pretreatment with allopurinol and 50 min of ischemia followed by 1 h of reperfusion. The effect of allopurinol was evaluated by plasma levels of alanine aminotransferase and aspartate aminotransferase, histopathologic studies, and lipid peroxidation measured by the thiobarbituric acid reactive substances method and chemiluminescence initiated by tert-butyl hydroperoxide technique. RESULTS: Ischemia followed by reperfusion promoted an increase in lipid peroxidation of the hepatic cells when compared to the sham-operated group (p<0.05). This increase was attenuated in the group treated with allopurinol (p< 0.05). Allopurinol also showed a protective effect on hepatocellular necrosis (p<0.05), and the plasma levels of liver enzymes returned earlier to the normal range in rats pretreated with allopurinol in comparison to those that did not receive the drug (p<0.05). CONCLUSIONS: Allopurinol exerted a protective effect on hepatic ischemia and reperfusion in rats. The administration of this drug prior to liver operations should be considered to be submitted to trials in humans.     

Melatonin does not inhibit estradiol-stimulated proliferation in MCF-7 and BG-1 cells

Melatonin, an indolic pineal hormone, is produced primarily at night in mammals and is important in controlling biological rhythms. Previous research suggested that melatonin can attenuate proliferation in the estrogen-responsive MCF-7 breast cancer cell line. We tested whether these anti-proliferative effects may have physiological consequences upon two estrogen-responsive cell lines, MCF-7 (a breast cancer cell line) and BG-1 (an ovarian adenocarcinoma cell line). Melatonin (10(-9)- 10(-5) M) attenuated proliferation of MCF-7 and BG-1 cells by >20% in the absence of estrogen. However, 17beta-estradiol exposure negated the ability of melatonin to inhibit proliferation. To substantiate this finding, cells were estrogen starved followed by multiple treatments with estradiol and melatonin. Melatonin did not inhibit estradiol- stimulated proliferation under this protocol. Estradiol increased MCF-7 and BG-1 cell cycle transition from G1 to S phase, however, melatonin did not inhibit this transition nor did it down-regulate estradiol- induced pS2 mRNA levels measured by northern blotting, further indicating that melatonin was unable to attenuate estradiol-induced proliferation and gene expression. We also examined the effects of melatonin on estradiol-induced proliferation in MCF-7 cell xenografts in athymic nude mice. Melatonin at a dose 28 times greater than 17beta- estradiol did not inhibit estradiol-induced proliferation in vivo. Furthermore, pinealectomy did not increase proliferation. Therefore, we conclude that melatonin does not directly inhibit estradiol-induced proliferation.      

Infant feeding, wheezing, and allergy: a prospective study

The determinants of wheezing and allergy were investigated in 453 children with a family history of allergic disease. A randomised controlled trial examined the effects of withholding cows' milk protein during the first three months of life and replacing cows' milk with soya milk. The children were followed up to the age of 7 years. Withholding cows' milk did not reduce the incidence of allergy or wheezing. Children who had ever been breast fed had a lower incidence of wheeze than those who had not (59% and 74% respectively). The effect persisted to age 7 years in the non-atopics only, the risk of wheeze being halved in the breast fed children after allowing for employment status, sex passive smoking, and overcrowding. Allergic disease was not associated with exposure to tobacco smoke, house dust mite antigen, or cats. Breast feeding may confer long term protection against respiratory infection.     

Abstracts of selected papers from the 1st ISOQOL Pan-Pacific Conference, Tokyo, Japan, April 13–15 2001

Abstract List

Abstracts of selected papers from the 1st ISOQOL Pan-Pacific Conference, Tokyo, Japan, April 13–15 2001     

Avoided and avoidable risks of cancer

Despite the considerable efforts and funds devoted to cancer research over several decades, cancer still remains a mainly lethal disease. Cancer incidence and mortality have not declined at the same rate as other major causes of death, indicating that primary prevention remains a most valuable approach to decrease mortality. There is general agreement that environmental exposures are variously involved in the causation of the majority of cancer cases and that at least half of all cancers could be avoided by applying existing etiologic knowledge. There is disagreement, however, regarding the proportion of cancer risks attributable to specific etiological factors, including diet, occupation and pollution. Estimates of attributable risks are largely based today on unverified assumptions and the calculation of attributable risks involves taking very unequal evidence of various types of factors and treating them equally. Effective primary prevention resulting in a reduction of cancer risk can be obtained by: (i) a reduction in the number of carcinogens to which humans are exposed; or (ii) a reduction of the exposure levels to carcinogens. Exposure levels that could be seen as sufficiently low when based on single agents, may actually not be safe in the context of the many other concomitant carcinogenic and mutagenic exposures. The list of human carcinogens and of their target organs might be quite different if: (i) epidemiological data were available for a larger proportion of human exposures for which there is experimental evidence of carcinogenicity; (ii) more attention was paid to epidemiological evidence that is suggestive of an exposure-cancer association, but is less than sufficient, particularly in identifying target organs; and (iii) experimental evidence of carcinogenicity, supported by mechanistic considerations, were more fully accepted as predictions of human risk.      

Trends in the health burden due to urinary tract infection in children in Australia

Objective: To estimate the health burden of urinary tract infection in children less than 15 years of age in Australia and to ascertain whether any significant change has occurred during the past decade. Methodology: The number of children less than 15 years of age who were admitted in New South Wales for urinary tract infection between 1981 and 1994 was ascertained from the Department of Health, and age and sex specific incidence rates were calculated using Australian Bureau of Statistics population data. Costs for inpatient care were calculated using the cost weights from Australia National Disease Related Groups Version 3 for urinary tract infection (DRG 577). The frequency of the four most commonly requested renal tract imaging procedures in children following urinary tract infection and which qualified for Medicare reimbursement were obtained from the Health Insurance Commission for 1984–1994: micturating cystourethrography, intravenous urography, renal ultrasonography, and nuclear medicine renal studies. Results: There were 1203 children who were admitted with urinary tract infection in New South Wales in 1994, at an estimated cost of $A1.6 million. Since 1981, the age standardized annual incidence of urinary tract infection requiring hospitalization has increased from 0.5 to 0.9 per 1000 children, largely because of an increase in the number of young children admitted (from 0.6 to 2.0 per 1000 children less than 5 years of age). In 1994, 46 230 non-inpatient renal imaging procedures were undertaken in children under 15 years of age at a cost of $A5.3 million. Conclusions: Urinary tract infection is an important and increasing health problem for Australian children, particularly for preschool children. Whether this represents a true increase in the incidence of urinary tract infection or improved diagnosis and more intensive management is not possible to establish with this study design. Prospective population based studies are required to assess more completely the frequency with which urinary tract infection occurs in children and any changes that may be occurring.     

Safety and immunogenicity of three doses of a five-valent pneumococcal conjugate vaccine in children younger than two years with and without human immunodeficiency virus infection

OBJECTIVE: To assess the safety and immunogenicity of three doses of a five-valent (types 6B, 23F, 14, 18C, and 19F) pneumococcal conjugate vaccine (PCV) among children younger than 2 years who are and are not infected with human immunodeficiency virus (HIV). METHODS: A convenience sample of 18 HIV-infected children 2 years and younger (mean, 12.9 months) received three doses (each separated by 2 months) of PCV. An additional convenience sample of 33 non-HIV-infected children of virtually identical age, race, and sex as the HIV-infected group were randomized in a double-blind fashion to receive three doses of PCV or saline placebo. Safety data were collected for 72 hours after each vaccination. Sera were obtained before each and 1 month after the third vaccination to determine vaccine type-specific immunoglobulin G pneumococcal antibody titers by an enzyme-linked immunosorbent assay. RESULTS: Seventeen HIV- and 30 non-HIV-infected children completed the study. The PCV was well tolerated by both HIV- and non-HIV-infected children. No significant differences in local or systemic reactions were noted between HIV- and non-HIV-infected PCV or placebo recipients. Three doses of PCV were immunogenic, as evidenced by 16- to 659-fold increases in type-specific geometric mean antibody titers over prevaccination levels in HIV- and non-HIV-infected children. With respect to an arbitrary protective level, 78% of the antibody titers from HIV-infected children and 88% of the titers from non-HIV-infected children were 1.0 microgram/mL or greater 1 month after the third PCV dose. HIV-infected children with milder disease (Centers for Disease Control and Prevention classes N1-2, A1-2, and B1) were more likely to have protective antibody titers after the first and second PCV doses than HIV-infected children with more advanced disease (Centers for Disease Control and Prevention classes N3, A3, B2-3, and C1-3). However, after the third PCV dose, these differences disappeared. CONCLUSION: Three doses of PCV seem safe and immunogenic in both HIV- and non-HIV-infected children younger than 2 years. This type of vaccine should result in a marked reduction in systemic pneumococcal disease in both HIV- and non-HIV-infected children. Given the high incidence of invasive pneumococcal disease in HIV-infected children, this vaccine may markedly improve the quality of life for this unfortunate group of children.     

The role of Epstein-Barr virus in Hodgkin's disease from different geographical areas

Recent studies have suggested that Epstein-Barr virus (EBV) may play a role in the aetiology of Hodgkin's disease. To determine the role of EBV in childhood Hodgkin's disease in different geographical areas, immunohistochemical staining and in situ hybridisation were used to analyse latent membrane protein 1 (LMP 1) and small nuclear non-transcribed RNAs (EBER-1) respectively. Testing for EBV within the Reed-Sternberg and Hodgkin's cells was carried out in childhood Hodgkin's disease from 10 different countries. The proportion of LMP 1 positive cases varied significantly, being 50% of cases from the United Kingdom (38/75), South Africa (9/18), Egypt (7/14), and Jordan (8/16), 60% from the United Arab Emirates (6/10), 70% from Australia (11/16), 81% from Costa Rica (34/42), 88% from Iran (7/8), 90% from Greece (20/22), and 100% of the 56 cases from Kenya. A sensitive polymerase chain reaction based EBV strain typing technique was established using archival tissues. EBV strain type 1 was shown to be predominant in childhood Hodgkin's disease from the United Kingdom, South Africa, Australia, and Greece. Type 2 was predominant in Egypt. EBV strain types 1 and 2 were both detected in some cases of childhood Hodgkin's disease in the United Kingdom, Costa Rica, and Kenya. The high incidence of EBV and the presence especially in developing countries of dual infection with both strain types 1 and 2 may reflect socioeconomic conditions leading to malnutrition induced immunological impairment. The possibility of HIV infection also needs to be explored.