Reduced toxicity and broad spectrum resistance to viral and fungal infection in transgenic plants expressing pokeweed antiviral protein II

Pokeweed antiviral protein II (PAPII), a 30 kDa protein isolated from leaves of Phytolacca americana, inhibits translation by catalytically removing a specific adenine residue from the large rRNA of the 60S subunit of eukaryotic ribosomes. The protein sequence of PAPII shows only 41% identity to PAP and PAP-S, two other antiviral proteins isolated from pokeweed. We isolated a cDNA corresponding to PAPII and introduced it into tobacco plants. PAPII expressed in transgenic tobacco was correctly processed to the mature form as in pokeweed and accumulated to at least 10-fold higher levels than wild-type PAP. We had previously observed a significant decrease in transformation frequency with PAP and recovered only two transgenic lines expressing 1-2 ng per mg protein. In contrast, eight different transgenic lines expressing up to 250 ng/mg PAPII were recovered, indicating that PAPII is less toxic than PAP. Two symptomless transgenic lines expressing PAPII were resistant to tobacco mosaic virus, potato virus X and the fungal pathogen Rhizoctonia solani. The level of viral and fungal resistance observed correlated well with the amount of PAPII protein accumulated. Pathogenesis-related protein PR1 was constitutively expressed in transgenic lines expressing PAPII. Although PR1 was constitutively expressed, no increase in salicylic acid levels was detected, indicating that PAPII may elicit a salicylic acid-independent signal transduction pathway.     

Achalasia in Down''s syndrome

Gastrointestinal disorders, including motor disorders of the esophagus, occur more frequently in patients with Down's syndrome than in the general population. We recently diagnosed achalasia in a man with Down's syndrome, an association reported only once before. Of the 643 patients with achalasia treated at our institution over a 30-year period (1962-1992), a total of three had Down's syndrome. We report their clinical, radiological, and manometric findings. Achalasia may be underdiagnosed in patients with Down's syndrome because their intellectual impairment may interfere with their ability to report symptoms adequately. All three patients responded well to conventional treatment.     

Inhibitory nerve distribution and mediation of NANC relaxation by nitric oxide in horse airways

The distribution of inhibitory nerves and the mediator of the inhibitory nonadrenergic noncholinergic (iN-ANC) nervous system were investigated in smooth muscle preparations from seven regions of equine airways. In tissues incubated with atropine and precontracted with histamine, electrical field stimulation produced frequency-dependent relaxation, and the magnitude of the relaxation decreased from trachea to central bronchi and was absent in peripheral airways. The degree of relaxation in bronchi was not simply a function of bronchial size or generation. Propranolol inhibited part of the relaxation only in the cranial trachealis. After propranolol, NG-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, eliminated the remaining relaxation in all preparations. This effect was reversed by L-arginine, the NO precursor, but not by D-arginine. Exogenous NO concentration dependently relaxed trachealis. These results indicate that: 1) adrenergic innervation is limited to cranial trachealis, 2) iNANC nerves supply the trachea and central bronchi, and 3) NO mediates iNANC function.     

The inhibition of human immunodeficiency virus proteases by 'interface peptides'

The active human immunodeficiency virus type 1 (HIV-1) protease has a homodimeric structure, the subunits are connected by an 'interface' beta-sheet formed by the NH2- and COOH-terminal amino acid segments. Short peptides derived from these segments are able to inhibit the protease activity in the range of micromolar IC50 values. We have further improved the inhibitory power of such peptides by computer modelling. The best inhibitor, the palmitoyl-blocked peptide Pam-Thr-Val-Ser-Tyr-Glu-Leu, has an IC50 value of less than 1 microM. Some of the peptides also showed very good inhibition of the HIV-2 protease. The C-terminal segment of the HIV-1 matrix protein, Acetyl-Gln-Val-Ser-Gln-Asn-Tyr, also inhibits HIV-1 protease. Kinetic studies confirmed the 'dissociative' mechanism of inhibition by the peptides. Depending on the peptide structure and ionic strength, both dimerization inhibition and competitive inhibition were observed, as well as synergistic effects between competitive inhibitors and interface peptides.     

The characteristics of the development of learned helplessness in rats selected for the excitability threshold of their nervous systems

To detect t(14;18)-positive cells present in human lymphoma tissue, bone marrow aspirates and peripheral blood mononuclear cells (PBMNC), we have established an automated, real-time quantitative PCR using double-labeled fluorogenic probes. In relation to t(14;18)-positive genomic DNA or a cloned t(14;18)-DNA fragment, highly reproducible results can be obtained with initial copy numbers between 10 to 10(5). The detection of single copies has been verified by the stochastic multiple-tube approach. PBMNC cells obtained during clinical follow-up of patients with follicular lymphoma were analyzed by the one-step, real-time quantitative PCR and a two-step, semi-nested PCR combined with a limiting dilution assay. The quantitative results obtained by both assays correlate very well. Real-time quantitative PCR has several advantages: (i) it involves less critical pipetting steps, (ii) is less time-consuming and (iii) UTP, in combination with uracil-N-glycosylase, can be used to control carryover contamination. The higher specificity is due to optimized primer annealing conditions and MgCl2 concentration and the use of AmpliTaq Gold. The sensitivity is at least as high as by the two-step PCR. Real-time quantitative PCR will be very helpful in large epidemiological studies and in research for molecular staging and the detection of minimal residual tumor cells, including the analysis of blood stem-cell preparations to be used for transplantation after myelo-ablative therapy.     

The contrast between physicians seen by the medical board and those seen in private practice

Twenty-two patients suffering from trigeminal neuralgia were treated by thermocoagulation from June 92 to June 94 at H?tel-Dieu de France Hospital. Epidemiological, clinical, para-clinical elements and the therapeutic approach were studied. The results after a median follow-up of one year were satisfactory in twenty patients (90.9%) who became asymptomatic. No major complication was noticed. Two recurrences occurred however, one responded to another thermolesion. We propose and discuss this technic for the treatment of the trigeminal neuralgia.     

Expression of different lipoprotein receptors in natural killer cells and their effect on natural killer proliferative and cytotoxic activity

Natural killer (NK) cells take up chylomicrons (CM), very low density (VLDL), low density (LDL), high density (HDL) and acetyl-modified low density (AcLDL) lipoproteins through different receptors, VLDL being the lipoprotein with the highest uptake and HDL the lowest. The uptake of LDL can be selectively blocked by the anti-LDL receptor, which does not affect the uptake of CM, VLDL, HDL and AcLDL. Although the uptake of lipoproteins assessed by flow cytometry using DiI is not very high, the lipoproteins are able to induce an increase in proliferative responses, VLDL, AcLDL and HDL being the most important ones with 12- and 17-fold increments, respectively. CM, VLDL and LDL at low concentrations increase NK cytotoxic activity, while HDL and AcLDL inhibit, in a dose-dependent fashion, the killing of NK cells against K562. These results suggest the presence of four different receptors that are responsible for the cytotoxic and proliferative responses observed.     

The effects of an angiotensin blocker (saralasin) on kidney function in dehydrated sheep

Saralasin, an angiotensin II analogue and receptor blocker, was infused at 7 and 15 micrograms . min-1 into dehydrated conscious Merino ewes. This caused mean arterial blood pressure, cardiac output, heart rate and renal vascular resistance to fall, and central venous pressure to rise. Renal plasma flow was unaffected but there were significant reductions in glomerular filtration rate, filtration fraction, urine flow, sodium and potassium excretion, solute clearance and solute-free water reabsorption. It is suggested that saralasin produced these effects by inhibiting endogenous angiotensin II activity, and in particular by causing a reduction in renal post-glomerular resistance. This in turn caused a fall in glomerular filtration rate and filtration fraction. While saralasin might have had effects on renal tubular function and perhaps on vasopressin secretion, the observed effects on renal function can be explained by the decrease in glomerular filtration rate and filtration fraction.