Regression of v-src DNA-induced sarcomas is under host genetic control.

Previous results have established that subcutaneous inoculation of chickens (line SC) with a v-src(+) subviral DNA fragment induces the formation of progressor sarcomas at the wing web site of inoculation. Because the sarcoma cells are incompetent for production of exogenous progeny virus, this system is a useful model of tumor expansion by sarcoma cell division, in the absence of infection-mediated recruitment of new tumor cells. The present study was undertaken to define conditions that modulate the pattern of growth (regression vs progression) of v-src DNA-induced sarcomas. These conditions were found to include the line of chicken or the presence on the subviral v-src(+) DNA fragment of a viral replication-specific sequence that includes env.     

Endometrial fluid collection in women with hydrosalpinx after human chorionic gonadotrophin administration: a report of two cases and implications for management

The impact of hydrosalpinx (HSPX) on in-vitro fertilization (IVF) outcome has recently been the subject of intense debate. Most, but not all, studies have reported decreased implantation and pregnancy rates and increased early pregnancy loss in HSPX patients. This has led to prophylactic salpingectomies prior to IVF in HSPX patients despite the lack of any prospective studies to suggest that any improvement will occur. Women with HSPX constitute a heterogeneous population because some conceive easily with IVF while others do not until after surgical correction. HSPX also increases in size with ovarian stimulation, and can cause implantation failure by fluid reflux into the uterine cavity. Careful assessment of the endometrial lining is mandatory in HSPX to rule out fluid reflux from the HSPX. We present two case reports of patients whose HSPX enlarged with ovarian stimulation, causing fluid reflux into the uterine cavity which was only noted after human chorionic gonadotrophin (HCG) administration.      

Altered neuronal sensitivity of lateral geniculate neurones to noradrenaline and 5-HT following exposure to continuous lighting

Rats were housed in either continuous lighting (LL), an extended photoperiod of 18 h light-6 h dark (LD 18:6) or a 12 h light-12 h dark (LD 12:12) lighting cycle. The effects of these various lighting regimens on the sensitivity of dorsal lateral geniculate neurones to iontophoresed noradrenaline and serotonin (5-HT) was examined. Exposure to either continuous lighting or to an extended photoperiod (LD 18:6) resulted in the development of an enhanced responsiveness to iontophoresed noradrenaline (alpha 1-adrenoceptor) and 5-HT. The development of light-induced noradrenaline and 5-HT supersensitivity resembles the changes obtained with antidepressant treatments.     

Japanese encephalitis virus-vaccinia recombinants produce particulate forms of the structural membrane proteins and induce high levels of protection against lethal JEV infection.

Four recombinant vaccinia viruses were engineered for expression of different portions of the Japanese encephalitis virus (JEV) open reading frame. All four recombinant vaccinias contained the NS1 and NS2A genes, and each of these viruses specified the synthesis, glycosylation, and secretion of the nonstructural glycoprotein (NS1). All four recombinants also contained the E gene, and each virus correctly directed the synthesis and glycosylation of the envelope glycoprotein (E). Interestingly, two of these viruses (vP555 and vP650), which expressed the prM gene in addition to E and NS1, produced an extracellular hemagglutinin containing M and E that migrated in sucrose gradients similarly to the slowly-sedimenting hemagglutinin found in the culture fluid of JEV-infected cells. Immunization of 3-week-old mice with the recombinant viruses vP555 and vP658 resulted in immune responses to NS1, whereas only the virus that directed the synthesis of extracellular forms of E (vP555) induced an immune response to E. Both viruses provided protection against lethal challenge with JEV. Animals given two inoculations with vP555 were fully protected from greater than 10,000 LD50 of JEV. This high level of protection was correlated with the production of high titers of neutralizing and hemagglutination-inhibiting antibodies.     

Detection of Cryptosporidium parvum oocysts in bovine feces by monoclonal antibody capture enzyme-linked immunosorbent assay.

A monoclonal antibody enzyme-linked immunosorbent assay (ELISA) was developed to detect Cryptosporidium parvum oocysts in bovine feces. Fecal oocysts were concentrated by centrifugation through Formalin-ethyl acetate solution and captured with monoclonal antibody 18.280.2 reactive with C. parvum oocysts. Captured oocysts were detected with goat anti-oocyst serum, following the addition of a peroxidase conjugate of rabbit anti-goat immunoglobulin and O-phenylenediamine substrate. The assay was specific for Cryptosporidium sp. oocysts and did not detect oocysts of Eimeria auburnensis, Eimeria bovis, Eimeria ellipsoidalis, or Eimeria zuernii. Assay sensitivity allowed detection of 3 x 10(5) oocysts per ml of feces, compared with 1 x 10(6) oocysts per ml detected by examination of acid-fast-stained fecal smears and 1 x 10(3) oocysts per ml detected by indirect immunofluorescence. The capture ELISA was suitable for diagnostic analysis of bovine fecal samples and for assessment of oocyst shedding in experimentally infected calves. This assay may also prove useful for diagnostic assessment of humans in which cryptosporidiosis is suspected.     

Dorsal bundle extinction effect: Motivation or attention?

Male albino Wistar rats were injected bilaterally with 4 micrograms of 6-hydroxydopamine into the dorsal noradrenergic bundle to deplete forebrain noradrenaline to less than 5% of control values. Acquisition learning of a fixed interval schedule or a continuously reinforced schedule was not altered but resistance to extinction was seen after food reinforced training on either schedule but not after water reinforced training. A possible increase in food motivation was tested by the use of preloading with free food prior to a fixed interval session but both control and lesioned rats reacted similarly to this manipulation thus appearing to exclude an increase in food motivation. An attentional explanation is proposed and tested by the demonstration that resistance to extinction does not occur after a partially (variable ratio 4), as opposed to a continuously, reinforced schedule. Further evidence in favour of an attentional mechanism comes from the finding that on both a fixed interval and a continuously reinforced schedule the lesion has to be present during the acquisition phase to result in subsequent resistance to extinction. Intact animals trained on either schedule and subsequently subjected to the lesion failed to show an increased resistance to extinction.     

Role of immunohistochemistry in diagnosis of nasopharyngeal tumours.

To evaluate the usefulness of immunocytochemistry in the differential diagnosis of nasopharyngeal tumours, 35 undifferentiated nasal carcinomas were examined with a panel of monoclonal antibodies against a wide variety of epithelial and non-epithelial antigens. The results were compared with those obtained from a series of nasopharyngeal tumours comprising three squamous cell carcinomas, six lymphomas, one rhabdomyosarcoma, and one yolk sac tumour. All of the carcinomas were positive with at least one of the antiepithelial markers and negative for the leucocyte common antigen and were clearly distinguishable from the nasopharyngeal lymphomas, which gave the opposite staining pattern. It was concluded that such a panel of monoclonal antibodies would be extremely useful for the differential diagnosis of nasopharyngeal tumours, particularly with small or technically inadequate biopsies.