Infections of forest rat filaria, Breinlia booliati, in neonate and juvenile laboratory white rats

The kinetics of Breinlia booliati infection in 3 inbred rat strains (Lewis, Wistar and Sprague Dawley) were investigated. One group of rats was infected as neonates (less than 24 hours of age) with third-stage larvae of B. booliati and the other group was infected as juveniles (4 weeks of age). The results showed that infection in the neonates were significantly different from the infection in the juveniles. The 60 rats infected as neonates, when necropsied between 8 to 10 months postinfection, yielded adult worms. The 2 neonatal infection groups of Lewis and Wistar strains showed highest susceptibility to the infections. The mean prepatent period was 85 days. Ninety to 95% of the infected rats were patent with microfilaraemia and a large percentage (33 to 47%) of them had high microfilaraemia counts exceeding 3000 mff/20 mm3 of blood and larger sizes (mean 157.11 mm for female adult worms and 61.88 mm for male adult worms. The adult worms were distributed equally in both the pleural (57%) and peritoneal cavity (43%). In most aspects, the neonatal infection group of the Sprague-Dawley strain was intermediate in susceptibility between the 2 neonatal infection groups of the Lewis and Wistar strains and the 3 juvenile infection groups. In contrast to neonatal infection groups, the 3 juvenile infection groups exhibited low infection rates (37%, 58% and 47% for the Lewis, Wistar and Sprague Dawley strains respectively), longer prepatent periods (mean 101 days), lower recovery rates (2 to 4%), lower adult worm loads (mean 0.4 to 0.8 female worms, and 0.2 to 0.8 male worms per rat), and smaller sizes (mean 141.24 mm for female adult worms and 53.75 mm for male adult worms). Forty-four to 57% of these infected rats harboured either single male or single female adult worms in the body cavity. Most (92%) of the adult worms recovered from the juvenile infection groups resided in the pleural cavity and the remaining 8% were recovered from the peritoneal cavity. Microfilaraemia could be detected in only 3/20 Lewis rats, 5/20 Wistar rats and 5/20 Sprague Dawley rats. The mean peak microfilaraemia of the 3 pooled juvenile infection groups was 632 mff/20 mm3 of blood, ranging from 7 mff/20 mm3 to 1856 mmf/20 mm3. Our results indicate that the susceptibility to B. booliati infection in white rats is both genetic and age-associated. The responses of the 2 distinct infection groups to B. booliati infections are discussed.     

Changing patterns of placental hexokinase isozymes during the course of gestation.

Hexokinase, an enzyme that is capable of regulating the entry of glucose into metabolic sequences, is known to exist in four isozyme forms in a variety of mammalian tissues. Each of these isozymes possesses different kinetic properties, suggesting that they may serve in different regulatory capacities. In addition, the proportions of the four isozymes are characteristically different for various differentiated tissues, presumably reflecting different metabolic capabilities of the tissues.Extracts of rabbit and human placentas from early gestational age and term pregnancies were chromatographed and assayed for hexokinase activity. Four peaks of activity were observed. Elution positions of the four placental hexokinase isozymes were comparable to those from liver; however, the relative proportions were considerably different. In both rabbit and human placentas, the proportion of Type I hexokinase increased during gestation and Type III decreased, while Types II and IV remained essentially unchanged. Implications of the gestational changes for placental carbohydrate metabolism are discussed.     

Ultrastructure of Amoebophrya sp. and its changes during the course of infection

Amoebophrya is a syndinian parasite that kills harmful bloom forming algae. Previously uncharacterized ultrastructural aspects of infection and development were elucidated. The biflagellate dinospore has two mitochondria, electron-dense bodies, striated strips, trichocysts, and a nucleus with peripherally condensed chromatin. After finding an Akashiwo sanguinea host and adhering to its surface, the parasite penetrates the host surface, apparently using a microfilament based motility and electron-dense bodies within a microtubular basket in the process of parasitophorous vacuole membrane formation. After entering the host nucleus, possibly by a similar mechanism used to enter the host cell, the parasite cytosol expanded substantially prior to mitosis. From 12-36 hours mitochondria were inconspicuous but present. Chromatin condensation was variable. By 36 hours post-infection, parasites had multiple nuclei, a microtubule-supported cytopharynx, and were beginning to form a fully internal mastigocoel. By 48 hours, the characteristic "beehive" appearance was apparent with flagella projecting into a fully developed mastigocoel. The cytoplasm contained trichocysts, elongated mitochondria, and nuclei with peripherally condensed chromatin. Although Amoebophrya lacks an apical complex, its electron-dense bodies show functional similarities to apicomplexan rhoptries. Its lack of permanently condensed chromosomes, but compact dinospore chromatin, supports the idea that dinoflagellate permanently condensed chromosomes may be a remnant of a parasitic ancestor with a compact dispersal stage.     

Biological effect of interferon-gamma during the course of experimental infection of rat by Schistosoma mansoni

We demonstrate here that a second mechanism of platelet activation dependent on lymphokine could also take place in the expression of platelet cytotoxicity against Schistosoma mansoni in vitro. Indeed, IgE, as previously described, but also IFN-gamma, present in the sera of infected rats, together induce platelets from normal rats into cytotoxic effectors for the parasitic larvae. This second mechanism appears also effective in vivo since the passive transfer of normal platelets treated by recombinant IFN-gamma (rIFN-gamma) and the administration of rIFN-gamma to rats conferred a protective immunity to S. mansoni.     

Trypanosoma lewisi: accumulation of antigen-specific host IgG as a component of the surface coat during the course of infection in the rat.

Naturally acquired host IgG, adsorbed to the surface of Trypanosoma lewisi during the course of infection in the rat, was labeled with fluorescein-conjugated rabbit IgG, or Fab fragments of this IgG, directed against rat IgG. The intensity of fluorescent labeling increases with time, concomitant with the increase in anti-T. lewisi activity of host plasma. Trypanosomes harvested from immunosuppressed hosts lack detectable surface IgG. Trypanosomes having little or no detectable surface IgG (harvested from immunosuppressed hosts or early in the infection from immunocompetent hosts) can adsorb IgG from serum with ablastic activity only (obtained from other infected rats between the first and second crises and adsorbed to remove trypanocidal antibodies), but not from normal serum. Therefore, the absence of detectable surface IgG on such cells is not caused by the parasites' inability to adsorb host IgG, but rather results from the immune state of the host. Hence surface IgG on T. lewisi is specific antibody. Host albumin is nonspecifically adsorbed, in contrast to IgG. Trypanosomes from immuno-suppressed and immunocompetent rats were positive and visually indistinguishable from each other when labeled with anti-rat albumin, and were equally agglutinable with anti-rat albumin serum.     

南亚热带森林群落种-多度的对数正态分布模型研究

通过对地处南亚热带的广东省黑石顶自然保护区森林群落的定点研究结果的分析表明：当用１,２,３,…分组每种个体数ｒ时,５个不同类型的群落样地的种一多度分布的直方图都呈明显的倒Ｊ－形;经Ｐｒｅｓｔｏｎ“倍程（ｏｃｔａｖｅｓ）”法分组ｒ后,其种－多度都服从对数正态分布。由种－多度模型可以推出另一新的模型一个体一多度分布模型,即Ｉ（Ｒ）＝２R0ＳＯＥＸＰ［［１ｎ２）２／４ａ２〕ＥＸＰ｛－ａ２（Ｒ－（ＲＯ＋１ｎ２／２ａ２）］２｝,它也符合对数正态分布。另外,还运用积分方法推导出估计总体（整个群落）中总种数Ｓ*和总个体数Ｉ*理论值的公式,用此公式估计的结果较为合理。     

Diverging diversity patterns of vascular plants and geometrid moths during forest regeneration on Mt Kilimanjaro, Tanzania

Aim This study investigates diversity patterns of vascular plants and plant‐feeding geometrid moths during montane rain forest regeneration in relation to the biogeographical and historical conditions of Mt Kilimanjaro. Location Investigations were undertaken on the south‐western slopes of Mt Kilimanjaro at altitudes between 2075 and 2265 m. Methods Thirteen plots were selected for this study. Four of these were situated in the middle of large clearings (> 1000 m²), three in secondary forest, two in mature forest remnants surrounded by secondary forest and four plots within continuous closed mature forest. Vascular plant species were recorded in an area of 20 × 20 m². Geometrid moths were attracted using lamps placed inside reflective gauze cylinders. Results Ninety‐three species of vascular plants were recorded on the plots. Plant diversity increased in the course of forest regeneration from clearings and secondary forest to mature forest remnants and mature forest. This increase was visible in all vegetation strata as well as in the species number of Dicotyledoneae. The diversity of geometrid moths conversely decreased from early to late successional stages. A total of 2276 Geometridae representing 114 morphospecies were included in the study. Local values of Fisher's α varied from 10.3 to 18.3 on clearings and in secondary forest, whereas they remained below 8.0 in mature forest and mature forest remnants. There was a significant negative correlation between the diversity of Geometridae and the number of dicots, and of plant species in the shrub layer. Main conclusions Contrary to an expected positive correlation between the diversity of vascular plants and herbivorous geometrid moths, diversity patterns of these two groups are strongly diverging due to biogeographical and ecological factors differently affecting the two groups. The increase in plant diversity can chiefly be explained with an increase in epiphyte diversity which is related to the occurrence of suitable habitats in extensive moss layers on huge Ocotea usambarensis (Engl.) trees in the mature forest. The low diversity of geometrid moths in these forests may be connected to the isolation and relatively young age of the montane rain forests on Mt Kilimanjaro. Hence only a small number of moth species adapted to the cool and perhumid conditions within moist mature forest have so far immigrated into these habitats, and time was insufficient for the evolution of many new species.     

Granulomatous reactivation during the course of a leprosy infection: reaction or relapse

Background

Leprosy is a chronic granulomatous infectious disease and is still endemic in many parts of the world. It causes disabilities which are the consequence of nerve damage. This damage is in most cases the result of immunological reactions.

Objectives

To investigate the differences between a type 1 leprosy (reversal) reaction and relapse on using histopathology.

Methods

The histopathological changes in 167 biopsies from 66 leprosy patients were studied. The patients were selected when their sequential biopsies demonstrated either different patterns or maintained the same pattern of granulomatous reaction over more than two years during or after the treatment of leprosy.

Results

In 57 of the patients studied, a reactivation was seen which coincided with a decrease in the bacteriological index (BI), suggesting that this reactivation (reversal reaction or type 1 leprosy reaction) coincides with an effective capacity for bacteriological clearance. In nine patients, an increase of the bacteriologic index (IB) or persistence of solid bacilli occurred during the reactivation, indicating proliferative activity, suggestive of a relapse. The histopathological aspects of the granulomas were similar in both groups.

Conclusion

Bacterioscopy provided the only means to differentiate a reversal reaction from a relapse in patients with granulomatous reactivation. The type 1 leprosy reaction may be considered as a part effective immune reconstitution (reversal, upgrading reaction) or as a mere hypersensitivity reaction (downgrading reaction) in a relapse.     

Haemoproteus columbae: course of infection, relapse and immunity to reinfection in the pigeon.

Studies were performed on the course of infection, relapse, and immunity to reinfection in 11 young pigeons infected with the avian malaria parasite Haemoproteus columbae Kruse. The prepatent period in our experiments varied between 22 and 37 days. The intensity and length of the initial infection period showed wide variations. During this period an initial periodicity of gametocyte production of about 12 days with peaks at about 6-8 and 18-20 days after patency was observed. The various modes of infection (fly bite, intramuscular, intravenous, or intraperitoneal inoculation of sporozoites) did not influence the intensity of the initial infection. No pathogenicity due to heavy infection with the parasite was observed. There was no periodicity of relapse occurrence, nor any correlation between the frequency of relapse and the intensity of the initial infection, and the phenomenon was not influenced by seasonal changes. Pigeons (Columba livia) that had recovered from previous infections were susceptible to reinfection, whereas pigeons with chronic infection acquired immunity (premunition).     

Studies on the preparation of rat liver plasma membrane fractions and on their polypeptide patterns

Plasma membrane and bile canalicular membrane fractions were prepared from rat liver using NaHCO3, NaHCO3--CaCl2, and K2HPO4-KH2PO4 buffers (all at pH 7.4). The amount (expressed as milligrams protein per gram liver) of plasma membrane fraction exceeded the amount of bile canalicular membrane fraction using each of these three media; the use of NaHCO3-CaCl2 afforded a substantially higher yield of both types of membranes. The two membrane fractions exhibited complex patterns of polypeptides (greater than 30) on sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. Several reproducible differences in polypeptide patterns were observable between the two membrane fractions; in particular, components possibly corresponding to the heavy chain of myosin and to action were prominent in the bile canalicular membrane fraction. The effects of incubation in the above three buffers and in Tris--HCl (pH 7.4) on the polypeptide patterns of both types of membrane were studied. Many polypeptides were released from each type of membrane in all of these media. Differential effects on the polypeptide patterns of either type of membrane fraction were observed among the various buffers. In terms of minimizing loss of polypeptides, in general, NaHCO3--CacCl2 appeared to be the best buffer and Tris--HCl the worst buffer. The significance of these results for the preparation and storage of liver cell plasma membrane fractions is briefly discussed.