Coating mass control system design for a continuous galvanizing line

The structure of a typical computer-based coating mass control system is derived which incorporates feedback and feedforward controllers based on recently developed adaptive mathematical models for the jet stripping process. Using conventional design techniques, three alternative types of feedback control algorithm are invstigated. The ‘pulse-and-wait’ algorithm is recommended for computer control applications due to its ease of implementation. Typical simulation results are presented for a range of strip speeds with and without errors in the model parameters. Emphasis is placed on the need to adjust some of the controller settings as a function of process conditions. A computer control system based on the previously outlined concepts has been commissioned on a modern continuous galvanizing line operating at speeds up to 170 m/min. Typical results are given illustrating the improvements achieved from manual and automatic control after the installation of a coating mass gauge.     

Cysteine protease inhibitors cure an experimental Trypanosoma cruzi infection

Trypanosoma cruzi is the causative agent of Chagas' disease. The major protease, cruzain, is a target for the development of new chemotherapy. We report the first successful treatment of an animal model of Chagas' disease with inhibitors designed to inactivate cruzain. Treatment with fluoromethyl ketone-derivatized pseudopeptides rescued mice from lethal infection. The optimal pseudopeptide scaffold was phenylalanine-homophenylalanine. To achieve cure of infection, this pseudopeptide scaffold was incorporated in a less toxic vinyl sulfone derivative. N-methyl piperazine-Phe-homoPhe-vinyl sulfone phenyl also rescued mice from a lethal infection. Six of the treated mice survived over nine months, three without further treatment. Three mice that had entered the chronic stage of infection were retreated with a 20-d regimen. At the conclusion of the experiments, five of the six mice had repeated negative hemacultures, indicative of parasitological cure. Studies of the effect of inhibitors on the intracellular amastigote form suggest that the life cycle is interrupted because of inhibitor arrest of normal autoproteolytic cruzain processing at the level of the Golgi complex. Parasites recovered from the hearts of treated mice showed the same abnormalities as those treated in vitro. No abnormalities were noted in the Golgi complex of host cells. This study provides proof of concept that cysteine protease inhibitors can be given at therapeutic doses to animals to selectively arrest a parasitic infection.     

Characterization of a recombinant Onchocerca volvulus antigen (Ov33) produced in yeast

A yeast (Saccharomyces cerevisiae) expression system has been adapted to produce reagent quantities of a major Onchocerca antigen, Ov33. Using a pool of monoclonal antibodies produced against third-stage larvae, a cDNA library constructed from adult O. volvulus worms was screened. Twenty-seven cDNAs were isolated, two of which had sequence homology to Ov33, a putative aspartyl protease inhibitor, which is the immunodominant antigen of O. volvulus. These cDNAs were expressed at high levels intracellularly or through the secretory pathway of S. cerevisiae. Localization studies using antisera produced against purified recombinant protein demonstrated that Ov33 is a very abundant parasite protein present in the hypodermis, muscle, and uterus of female worms, as well as in embryonic microfilariae. The soluble recombinant protein secreted by yeast (C71) demonstrated inhibitory activity against the aspartyl protease pepsin. Antibodies to the recombinant protein-mediated leukocyte adherence to and killing of skin microfilariae. The sensitivity of a diagnostic test using recombinant Ov33 was evaluated using sera from 441 patients. The mean sensitivities for the two recombinant constructs, C27 and C71, were 82.2% and 85.4%, respectively. The combined sensitivity using both recombinant proteins was 94%.     

Evaluation of a stage-specific proteolytic enzyme of Schistosoma mansoni as a marker of exposure

Cercarial elastase (CE) is one of the first proteins released in the host by invading schistosome cercariae. An enzyme-linked immunosorbent assay (ELISA)-formatted immunoassay has been developed to detect antibodies to the stage-specific CE antigen of Schistosoma mansoni as marker of exposure. We have evaluated this test system as an epidemiologic tool, using well-characterized sera collected from S. mansoni- and S. haematobium-infected subjects residing in endemic areas and from control subjects living in nonendemic areas in Egypt. Urine, stool specimens, and blood samples were collected from a sample of 272 endemic subjects randomly selected to represent different age groups in the range of 2-20 years of age. Of 47 S. mansoni-infected subjects, 41 (87.2%) had anti-CE IgG antibodies. Of 52 S. haematobium-infected cases, 38 (73.0%) had IgM antibodies to CE and 43 (82.7%) had IgG antibodies to CE. Of 173 egg-negative people in the endemic area, 84 (48.6%) were IgM positive and 99 (57.2%) were IgG positive. The mean IgM and IgG antibody levels were similar in the infected groups but were significantly lower in the egg-negative group (P = 0.001). All sera from young children (2-3 years of age) were uniformly ELISA negative. The prevalence of IgM and IgG antibodies to CE in children less than six years of age were significantly lower than in other age groups. There was no significant difference in prevalence rates of IgM and IgG anti-CE antibodies between subjects having other parasites present in the endemic area (Ascaris lumbricoides, Entrobius vermicularis, Hymenolepis nana, H. diminuta, Trichostrongylus spp., and Entamoeba histolytica) and those without any parasitic infection. All nonendemic sera (58), including those with other helminth infections, were uniformly ELISA negative for antibodies to CE. These findings suggest that antibodies to elastase indicate exposure, but not necessarily active schistosome infection.     

Routine nasal surgery: an audit of outpatient follow-up

The study objective was to assess the value of outpatient follow-up of patients who undergo routine uncomplicated nasal surgery. A total of 177 postoperative patients (117 males, 60 females) undergoing routine nasal surgery at the Raigmore Hospital, Inverness, was selected over a six-month period, 92 of whom (60 males, 32 females) were requested to return to the clinic for a follow-up session. A total of 72 (78.3%) patients attended for post-operative review. Of these, 55 patients (76.4%) had achieved a satisfactory result from surgery and 17 (23.6%) required additional treatment for persistent problems. The former group were pleased with the outcome of their operation and required no further treatment. Of the 25 patients who were prescribed medication at the time of discharge from hospital, 19 (76.0%) were still complying with the medication and required no further specialist assistance. The results suggest that routine follow-up of uncomplicated cases of nasal surgery is unnecessary. The good therapeutic results in the majority of cases indicate a need to decrease the number of routine reviews to reduce the high non-attendance rate and increase the proportion of new patients seen at outpatient clinics. The role played by general practitioners is vital to this cause. This would include minor postoperative care, monitoring of prescribed medication and review of patients with occasional postoperative problems.