Single lead acetate insult, testosterone therapy, and erythropoiesis in mice

Lead acetate (PbAc) was tested for its effects on the production and release of erythrocytes-that is, erythropoiesis-in ICR mice. Dose-survival data indicate that a dosage of 20 mg PbAc/100 g body weight represents the maximum tolerable treatment level. No differences in survival at the various levels of the salt were observed with regard to sex or age. For erythropoietic effects of PbAc, mice were injected on day O, and radioiron (59Fe) incorporation percentages were determined at daily intervals through day 8 for both erythrocytes and splenic tissue. Control mice received isotonic saline as the injectate. On day 3, the percentages obtained from PbAc-treated mice showed a decline, reaching their minimum value by day 4. Recovery from erythropoietic suppression appeared to be complete by day 6 or 7; no positive overshoots in 59Fe percentages were found following recovery. These trends were typical for both peripheral red blood cells and spleen. Testosterone was administered to mice receiving saline or PbAc on two consecutive days (days -1 and O). Radioiron uptake percentages for females receiving testosterone and saline showed an abrupt increase on day 4. No accelerative effect due to testosterone was found in recipient males. For females treated with testosterone and PbAc, the radioiron percentages for erythrocytes and spleen paralleled those for females receiving saline only. Male mice treated with both androgen and PbAc demonstrated 59Fe percentages typical of males treated with PbAc alone.     

Seroprevalence survey of Egyptian tourism workers for hepatitis B virus, hepatitis C virus, human immunodeficiency virus, and Treponema pallidum infections: association of hepatitis C virus infections with specific regions of Egypt

Blood samples from 740 Egyptian Nationals working in the tourism industry at two sites in the South Sinai governorate were screened for markers of infection with hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and Treponema pallidum. Study subjects included 467 individuals from a rural seashore tourist village and 273 persons at two hotels in a well-established resort town. Subjects' ages ranged from 15 to 70 years; 99.3% were male. The prevalence of serologic markers for currently asymptomatic or past HBV infection alone was 20.7% (n = 153), of markers for past or chronic HCV infection alone was 7.4% (n = 55), and of markers for both HBV and HCV was 6.9% (n = 51). Of the 204 individuals positive for anti-HBV core antibody, 12 (5.9%) were also positive for hepatitis B surface antigen. Two individuals (0.3%) had a serologic market suggestive of an active syphilitic infection. No subject was found to be HIV-seropositive. History of prior injections and number of injections were associated with infection with HCV. Primary residence in the Nile delta and valley areas where schistosomiasis is highly endemic, was also a statistically significant risk factor for HCV, but not HBV infection.     

Isolation of a superfamily of candidate disease-resistance genes in soybean based on a conserved nucleotide-binding site

The tobacco N and Arabidopsis RPS2 genes, among several recently cloned disease-resistance genes, share highly conserved structure, a nucleotide-binding site (NBS). Using degenerate oligonucleotide primers for the NBS region of N and RPS2, we have amplified and cloned the NBS sequences from soybean. Each of these PCR-derived NBS clones detected low-or moderate-copy soybean DNA sequences and belongs to 1 of 11 different classes. Sequence analysis showed that all PCR clones encode three motifs (P-loop, kinase-2, and kinase-3a) of NBS nearly identical to those in N and RPS2. The intervening region between P-loop and kinase-3a of the 11 classes has high (26% average) amino acid sequence similarity to the N gene although not as high (19% average) to RPS2. These 11 classes represent a superfamily of NBS-containing soybean genes that are homologous to N and RPS2. Each class or subfamily was assessed for its positional association with known soybean disease-resistance genes through near-isogenic line assays, followed by linkage analysis in F2 populations using restriction fragment length polymorphisms. Five of the 11 subfamilies have thus far been mapped to the vicinity of known soybean genes for resistance to potyviruses (Rsv1 and Rpv), Phytophthora root rot (Rps1, Rps2, and Rps3), and powdery mildew (rmd). The conserved N- or RPS2-homologous NBS sequences and their positional associations with mapped soybean-resistance genes suggest that a number of the soybean disease-resistance genes may belong to this superfamily. The candidate subfamilies of NBS-containing genes identified by genetic mapping should greatly facilitate the molecular cloning of disease-resistance genes.     

Inhibition of in vitro replication of the oyster parasite Perkinsus marinus by the natural iron chelators transferrin, lactoferrin, and desferrioxamine

The mammalian iron-binding proteins transferrin and lactoferrin, the bactericidal peptide lactoferricin B, and the bacterial siderophore desferrioxamine were tested for their ability to inhibit the in vitro replication of the oyster parasite Perkinsus marinus. All three chelators were effective in reducing the parasite proliferation in a dose-dependent manner. Lactoferricin B, a peptide of lactoferrin that exhibits bactericidal properties unrelated to iron chelation, had no inhibitory activity on the parasite. When the chelators were partially or completely saturated with the appropriate iron equivalents, their inhibitory effects on the parasite proliferation were diminished or abolished accordingly, confirming that this activity was related to the chelator's capacity for iron sequestration. Our results indicate that the parasite has a strong requirement for soluble iron and its growth rates are correlated with iron availability. We propose that excess iron accumulation in the host Crassostrea virginica promotes parasite proliferation. P. marinus may avoid oxidative damage that would compromise its intracellular survival by exhaustion the host's intracellular selected iron pools required for superoxide and hydroxyl radical production.     

Hospital-associated bacterial meningitis

Eighteen of 349 cases (5.2 per cent) of bacterial meningitis seen between 1949 and 1973 were hospital-associated (developed after admission to the hospital). The patients were adults, usually males, and developed symptoms and signs of meningitis from 2 to 23 days (mean, 10.1 days) after hospital admission. The diagnosis of bacterial meningitis was made from less than 1 day to 15 days (mean, 4.8 days) after the onset of symptoms. Fourteen of the 18 patients had received antibiotics during the week prior to developing meningitis. Nine (50 per cent) had a chronic, noninfection, underlying illness. Diagnostic or surgical procedures involving the neuraxis or adjacent structures preceded the development of meningitis in 10 of the 18 patients (56 per cent). Only 6 of the 18 patients survived their infection. Prompt recognition, diagnosis, and therapy of hospital-associated meningitis in high-risk patients may reduce the significant mortality.