Relationship between tumor necrosis factor alpha and feline immunodeficiency virus expressions.

The presence of feline immunodeficiency virus (FIV) proviral DNA, expression of FIV p26 core protein, and production of tumor necrosis factor alpha (TNF-alpha) were assessed in sequential biopsies of spleen and lymph node sections, of mononuclear cells of the peripheral blood, and of the serum of specific-pathogen-free cats during the acute phase of FIV infection. A temporal relationship between TNF-alpha production and FIV p26 expression was noted. Two months following FIV infection, and preceding the detection of FIV viremia, levels of TNF-alpha in serum increased significantly (P = 0.04), and they remained elevated during FIV viremia in the third month postinfection. Immunoprecipitates representing expression of TNF-alpha and of FIV p26 were localized in common foci of lymph nodes of FIV-infected cats during this period of active viremia. With the advent of anti-FIV antibodies, circulating levels of TNF-alpha and p26 antigen and expression of TNF-alpha and p26 in the lymph nodes decreased during the fifth month postinfection, and p26 production became undetectable. With clearance of viremia, burden of proviral DNA in peripheral blood mononuclear cells became reduced (P = 0.041), with provirus remaining integrated principally within lymph nodes (P = 0.046). During aviremia, p26 expression was undetectable in any tissue but remained inducible in vitro. During acute FIV infection, TNF-alpha production and p26 expression are intimately linked.     

Changes in leaf expansion and epidermal screening effectiveness in Liquidambar styraciflua and Pinus taeda in response to UV-B radiation

Absorption or screening of ultraviolet-B (UV-B) radiation by the epidermis may be an important protective method by which plants avoid damage upon exposure to potentially harmful UV-B radiation. In the present study we examined the relationships among epidermal screening effectiveness, concentration of UV-absorbing compounds, epidermal anatomy and growth responses in seedlings of loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar styraciflua L.). Seedlings of each species were grown in a greenhouse at the University of Maryland under either no UV-B radiation or daily supplemental UV-B radiation levels of 4, 8 or 11 kJ m^?2 of biologically effective UV-B (UV-B_BE) radiation. Loblolly pine seedlings were subsequently grown in the field under either ambient or supplemental levels of UV-B radiation. At the conclusion of the growing season, measurements of epidermal UV-B screening effectiveness were made with a fiber-optic microprobe. In loblolly pine, less than 0.5% of incident UV-B radiation was transmitted through the epidermis of fascicle needles and about 1% was transmitted in primary needles. In contrast, epidermal transmittance in sweetgum ranged from about 20% in leaves not preconditioned to UV-B exposure, to about 10% in leaves grown under UV-B radiation. The concentration of UV-absorbing compounds was unaffected by UV-B exposure, but generally increased with leaf age. Increases in epidermal thickness were observed in response to UV-B treatment in loblolly pine, and this accounted for over half of the variability in UV-B screening effectiveness. In spite of the low levels of UV-B penetration into the mesophyll, delays in leaf development (both species) and final needle size (loblolly pine) were observed. Seedling biomass was reduced by supplemental UV-B radiation in loblolly pine. We hypothesize that the UV-induced growth reductions were manifested by changes in either epidermal anatomy or epidermal secondary chemistry that might negatively impact cell elongation.     

Screening for cervical intraepithelial neoplasia in north east Scotland shows fall in incidence and mortality from invasive cancer with concomitant rise in preinvasive disease.

OBJECTIVE--To assess the effect of screening for cervical intraepithelial neoplasia on the incidence of and mortality from invasive squamous cell carcinoma of cervix in north east Scotland and to discover why cases of invasive cancer still occur. DESIGN--(a) Analysis of data on cases of cervical intraepithelial neoplasia obtained from the cytology data bank; (b) analysis of data on 612 women presenting with invasive squamous cancer during 1968-91, obtained from cancer registry and hospital records; (c) analysis of death rates obtained from the registrar general''s (Scotland) annual reports, the Information Services Division of the Home and Health Department (Scotland), and local records for 1974-91; (d) case-control studies on 282 cases of invasive cancer and 108 deaths which occurred in 1982-91. Cases were matched with two controls both for age and for having a negative smear test result at the time of presentation of the case. SETTING--North east Scotland (Grampian region, Orkney, and Shetland). SUBJECTS--Women (n = 306,608) who had had cervical smear tests between 1960 and 1991. RESULTS--There had been a substantial increase in cases of cervical intraepithelial neoplasia grade III since 1982. The incidence of invasive cancer has fallen since the start of screening in 1960, the fall occurring mainly in the well screened age group 40-69 years. There was a rise in women aged under 40 and over 70. Women with invasive disease seen between 1982 and 1991 mostly presented at stage I. Of these, half were unscreened, one third were poorly screened, 11% were found in retrospect to have had abnormal cells, 3% had recurrence of disease after treatment for cervical intraepithelial neoplasia grade III, and 3% were lost to follow up. Death rates had fallen, most noticeably in women aged 45-64, who had had the opportunity to be screened and rescreened. There was a disturbing rise in deaths among women under 45. Most deaths (65%) occurred in unscreened women. Case-control studies showed that the longer the time and absence of a smear test before presentation the higher was the risk of invasive cancer and of death. CONCLUSIONS--Screening has been effective in reducing the incidence of and mortality from cervical cancer in north east Scotland. Most cases and deaths occurred in unscreened women or in those who had had few smears at long intervals. An increase in cases of cervical intraepithelial neoplasia grade III in women screened for the first time occurred during 1982-91.     

The world-wide web and plant molecular biology

The Internet has been functional since 1967 and has been operating without interruption for over 20 years. Although local service can be lost, the network will retain its integrity and recover from almost any imaginable combination of faults, whether natural or intentional. This robustness, the global scope, the availability of quality public domain software, and the inherent democracy of the Internet, have combined to eclipse similar efforts. Many scientists have found the Internet immediately useful for communication in the form of electronic mail. Shared resources, an intrinsic benefit of networks, are now becoming apparent in the form of the World-Wide Web (WWW).     

Characterization of seminal plasma proteins and sperm proteins in ejaculates from normospermic bulls and bulls with thermally-induced testicular degeneration

Semen was collected from 5 mature beef bulls by electroejaculation before, during, and after 20 days of scrotal insulation. Thermally-induced testicular degeneration was irreversible in 3 of the bulls. Analysis of sperm and seminal plasma polypeptides revealed that 15 to 30 sperm polypeptides and 25 to 30 seminal plasma polypeptides were indistinguishable between bulls prior to the insulation treatment. Changes in the sperm polypeptides pattern appeared as early as 2 days after the insulation treatment and persisted for at least 11 months in 2 of the bulls. In the spermatozoa, there was a detectable loss of 31, 34, 49 and 58 kDa polypeptides and an appearance of 6 to 8 new major polypeptides, ranging from 32 to 83 kDa. The 83 kDa polypeptide was most prominent in the 2 bulls that regained normal sperm motility and morphology following the insulation period. The post-insulation appearance of a seminal plasma polypeptide (circa 60 kDa) was also identified in these 2 bulls. Seminal plasma polypeptides remained qualitatively unaltered by the insulation treatment in the 3 bulls with irreversible testicular degeneration.     

Bacteriological evaluation of groups of beef carcasses before the wash at six Alberta abattoirs

K.W.F. JERICHO, J.A. BRADLEY AND G.C. KOZUB. 1994. A method has been developed for the bacteriological evaluation of groups of beef carcasses which can be used to measure the degree of control over hygiene during hide removal and carcass dressing in abattoirs. This method, which enumerates aerobic mesophilic bacteria automatically using a hydrophobic grid membrane filter, was applied at six abattoirs. Two hundred excision samples (5 × 5 × 0.5 cm) were taken at 10 sites on the external surface of a group of 20 carcasses (five carcasses were sampled on each of four consecutive daily visits) for group-carcass evaluation at each abattoir. For each abattoir, the mean log₁₀ Most Probable Number of Growth Units (MPNGU) and between-carcass variance component were obtained for each site and the average over sites. Using the average within-abattoir variance of this study and previously published studies involving 76 additional carcasses (Jericho et al. 1993), it was determined that 20 carcasses are more than adequate to estimate the mean log₁₀ MPNGU per cm² within 0.5 units at a site. The distribution of the log₁₀ MPNGU per cm² over the 10 sites was compared for the abattoirs, and sites were found to cluster into 2–4 homogenous groups. The means over sites of log₁₀ MPNGU per cm² for the abattoirs ranged from 1.52 to 2.64 and were unrelated to line speed     

The influence of sampling method on the classification of wetland macroinvertebrate communities

Macroinvertebrate communities sampled by a corer, plankton net and sweep net from five wetlands on the Swan Coastal Plain were compared. The composition of the fauna collected in sweeps and tows was generally similar and differed from that collected in the cores. Cores caught fewer species than tows and sweeps at all wetlands and did not capture fast swimming hemipterans or less abundant taxa. The highest species richness was recorded in sweep samples in four out of the five wetlands. Classification (TWIN-SPAN) and ordination (SSH) of the samples collected in sweeps and tows gave good separation of the wetlands, whereas classification of core samples did not. Coring appeared to be the least suitable sampling method for describing the major components of the macroinvertebrate communities of these wetlands. Plankton tows were useful if the time available for sorting was limited as these samples were free of sediments and generally gave similar results to those obtained with sweeps. Sweeps appeared to be the most useful method for a large classification study as they collected more species and resulted in the best discrimination amongst wetlands.