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Biomedical subjects

C W Robinson

Publications and source records attributed to C W Robinson.

At least 19 recordsLinked to original sources
PubMed2001

BOD5 estimation for pulp and paper mill effluent using UV absorbance.

A novel method based on UV absorbance, is presented for estimating the BOD5 in pulp and paper mill effluent. This method could eventually be incorporated into an on-line sensor for BOD5 that is suitable for process control applications. Two streams, the reactor entrance and the final effluent, from two different mills were studied. One mill employed the Kraft pulping process, while the second mill was a thermo-mechanical one. The absorbance over the range 200-350 nm showed significant differences between the two mills. Because the two mills use very distinct processes, separate correlations were used to relate the absorbance to the BOD5 for both the mills. Results indicate that prediction of reactor entrance BOD5 was reasonable, whereas prediction of final effluent BOD5 was inaccurate, for both mills. Also studied was the effect of aeration on BOD5 results obtained at low BOD5 values for the Kraft mill.

Industrial Waste↗
PubMed2000

Effect of temperature on the inhibition kinetics of phenol biodegradation by Pseudomonas putida Q5.

The temperature-dependent performance of mixed-culture wastewater treatment processes may be strongly influenced by their content of psychrotrophic bacteria. In this work, the effect of temperature on cell growth and phenol biodegradation kinetics of the psychrotrophic bacterium Pseudomonas putida Q5 were determined using both batch and continuous cultures in the range of 10-25 degrees C. The Haldane equation was found to be the most suitable substrate-inhibition model for the specific growth rate. The Haldane parameters mu(max) and K(I) were best modeled by a square-root dependency on temperature. However, the Arrhenius model provided a better prediction of the temperature dependence of K(S). The variation of the yield constant with temperature also was studied experimentally. Comparisons with results of previous workers are presented.

Biodegradation, Environmental↗
PubMed2000

Production of tomato flavor volatiles from a crude enzyme preparation using a hollow-fiber reactor.

In recent years there has been an increase in the interest in the production of compounds by isolation from natural sources or through processes that can be deemed "natural". This is of particular interest in the food and beverage industry for flavors and aromas. Hexanal, organoleptically known to possess "green character", is of considerable commercial interest. The objective of this study was to determine if the enzyme template known to be responsible for the synthesis of hexanal from linoleic acid (18:2) in tomato fruits could be harnessed using a hollow-fiber reactor. A hollow-fiber reactor system was set up and consisted of a XAMPLER ultrafiltration module coupled to a reservoir. The enzyme template was extracted from ripe tomato fruits and processed through an ultrafiltration unit (NMWC of 100 kDa) to produce a retentate enriched in soluble and membrane-associated lipoxygenase (LOX) and hydroperoxide lyase (HPL). This extract was recirculated through the lumen of the hollow-fiber ultrafiltration unit with the addition of substrate in the form of linoleic acid, with buffer addition to the reaction flask to maintain a constant retentate volume. Product formation was measured in the permeate using solid phase microextraction (SPME) developed for this system. At exogenous substrate concentrations of 16 mM and a transmembrane pressure of 70 kPa, hexanal production rates are in the order of 5.1 microg/min. Addition of Triton X-100 resulted in membrane fouling and reduced flux. The reactor system has been run for periods of up to 1 week and has been shown to be stable over this period.

Aldehyde-Lyases↗
PubMed2000

Optimizing the expression of a monoclonal antibody fragment under the transcriptional control of the Escherichia coli lac promoter.

The expression of a monoclonal antibody Fab fragment in Escherichia coli strain RB791/pComb3, induced with either lactose or isopropyl-beta-D-thiogalactoside (IPTG), was compared to determine if lactose might provide an inexpensive alternative to induction with IPTG. Induction of Fab expression imposed a metabolic load on the recombinant cells, resulting in lower final cell yields compared to the non-induced controls. An IPTG concentration of 0.05 mM was sufficient to achieve maximal expression of soluble Fab protein when inducing in the early-, mid-, or late-log phases of batch cultures grown using either glucose or glycerol as a carbon source. The largest overall yield of Fab fragments when using 0.05 mM IPTG was achieved by increasing the final yield of cells through glycerol feeding following induction in late-log phase. Lactose was as effective as IPTG for inducing Fab expression in E. coli RB791/pComb3. The greatest overall level of Fab expression was found when cells grown on glycerol were induced with 2 g/L lactose in late-log phase. Since the cost of 0.05 mM of IPTG is significantly greater than the cost of 2 g/L lactose, lactose provides an inexpensive alternative to IPTG for inducing the expression of Fab fragments, and possibly other recombinant proteins, from the E. coli lac promoter.

Antibodies, Monoclonal↗
PubMed1998

Double inhibition model for degradation of phenol by Pseudomonas putida Q5.

A semiempirical model, based on the presence of an inhibitory intermediate metabolite excreted to the broth, was developed to better predict the dynamic responses to shock loadings of Pseudomonas putida Q5 degrading phenol. Compared to the Haldane equation, the new model exhibited better prediction capabilities for a broad range of inlet concentration and dilution rate step changes. The experiments were performed at 10 degrees and 25 degrees C and ranged from stable responses to washouts. The time delays observed experimentally were successfully predicted with the dual-inhibition model and a very good agreement with the observed phenol profile also was found in a pulse experiment. A possible intermediate metabolite was detected by HPLC analyses based on the high correlation shown with the predicted inhibitory intermediate metabolite in the model.

Biodegradation, Environmental↗
PubMed1996

Review: optimizing inducer and culture conditions for expression of foreign proteins under the control of the lac promoter.

This review examines factors which influence the expression of foreign proteins in Escherichia coli under the transcriptional control of the lac and tac promoters, and discusses conditions for maximizing the production of a foreign protein using this system. Specifically, the influence of IPTG (isopropyl-beta-D-thiogalactoside) concentration, temperature, composition of the growth medium, the point in the growth curve at which cells are induced with either IPTG or lactose, and the duration of the induction phase are discussed.

Culture Media↗
PubMed1988

Transfer and expression of mesophilic plasmid-mediated degradative capacity in a psychrotrophic bacterium.

A psychrotrophic bacterium, originally isolated from a natural aquatic environment, was characterized and identified as Pseudomonas putida Q5 for use as a representative recipient for biodegradative genes from a mesophilic microorganism. The TOL plasmid pWWO of the mesophile P. putida PaW1 was successfully transferred by conjugation to the naturally isolated psychrotroph P. putida Q5, as shown by plasmid analysis by agarose gel electrophoresis. Expression of the genes encoded by the mesophilic TOL plasmid in the psychrotroph was shown by the fact that the transconjugant (designated P. putida Q5T) had the capacity to degrade and utilize toluate (1,000 mg/liter) as a sole source of carbon at temperatures as low as 0 degrees C. Comparison of growth rates over a wide temperature range (0 to 30 degrees C) indicated that the physiological activity of the transconjugant was not reduced and that the plasmid DNA from the mesophile and its encoded enzymes functioned effectively in the psychrotroph at temperatures well below those at which the mesophile could grow. The production and demonstrated functioning of P. putida Q5T illustrates the possibility of developing specific degradative capacities in bacteria which can readily function at low temperatures in chemically contaminated environments or in industrial wastewater treatment systems.

Benzoates↗
PubMed1986

Acute and chronic effects of nicardipine on systolic and diastolic left ventricular performance in patients with heart failure: a pilot study.

Nicardipine is a new calcium ion antagonist with vasodilating properties which has been shown to be effective in the treatment of hypertension and angina. We have studied its effect on systolic and diastolic left ventricular function in patients with mild to moderate degrees of congestive heart failure. Ten male patients with New York Heart Association Class II and III heart failure underwent acute treatment with an intravenous infusion of nicardipine (10 mg over 10 minutes). A nuclear probe was used to monitor left ventricular ejection fraction, peak filling rate, and relative cardiac output. Blood pressure and heart rate were also measured. The blood pressure (mean +/- SD) fell from 133 +/- 26/86 +/- 11 mmHg to 103 +/- 22/69 +/- 13; the heart rate rose from 67 +/- 9 beats/min to 85 +/- 10; left ventricular ejection fraction from 31 +/- 7 to 38 +/- 6%; relative cardiac output from 24 +/- 9 to 41 +/- 11; peak filling rate from 1.18 +/- 0.4 end-diastolic volume per second to 1.82 +/- 0.4 (p less than 0.001 in all cases) at the end of infusion. After 4 weeks of chronic treatment in eight patients (20 mg to be taken three times daily (tds) in one and 40 mg tds in 7), the blood pressure and heart rate had returned to baseline values but the improvements in left ventricular ejection fraction, relative cardiac output, and peak filling rate were sustained; this was associated with functional improvement in all 8 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1986

Tiapamil, a new calcium channel blocking agent for the treatment of effort induced chronic stable angina pectoris.

The anti-anginal efficacy of tiapamil, a new calcium channel blocking agent was studied in 24 patients with established effort induced chronic stable angina pectoris. The patients were allocated randomly in a double-blind fashion to tiapamil 300 mg thrice daily or placebo for 2 weeks and thereafter all the patients received tiapamil 300 mg thrice daily in a single-blind fashion for a further 2 weeks. All patients performed symptom limited multistage graded exercise testing with computer-assisted analysis of the electrocardiogram before entering the study and at the end of the double-blind and single-blind phases. The mean exercise time to develop angina during the control test in the group which received placebo during the double-blind phase was 7.1 min; this increased to 8.5 min after 2 weeks of placebo and 9.7 min after 2 weeks of subsequent tiapamil therapy. Similarly in the group which received tiapamil during the double-blind phase the mean exercise time on control test was 6.4 min, increasing to 9.7 min and 9.7 min after 2 and 4 weeks of tiapamil therapy respectively. There were no statistical significant differences between the changes from control, seen with tiapamil and placebo during the double-blind phase. However, the changes observed between control and active therapy in the tiapamil group did reach statistical significance (p = 0.003). Similarly, 1 mm ST-segment depression time was prolonged by tiapamil therapy. The heart rate at rest and maximal exercise remained unaltered with tiapamil therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Reproducibility of multistage graded exercise testing in patients with chronic stable angina.

Exercise testing is widely used for the diagnosis of ischaemic heart disease and for the evaluation of antianginal drugs. To assess reproducibility, analysis was carried out on 128 paired graded exercise tests from 103 patients performed at the same time of day and under identical conditions. Six different parameters were evaluated and compared between the basal test (no treatment) and the placebo test. During the basal period the mean (+/- SEM) exercise time to the development of angina was 6.0 (+/- 0.2) min and the 1 mm ST depression time was 4.1 (+/- 0.2) min. After 2 weeks of placebo the exercise time was 6.1 (+/- 0.2) min (P = NS) and the 1 mm ST depression time was 4.2 (+/- 0.2) min (P = NS). There was no significant difference between the resting or maximum heart rate on either test and the maximum ST segment depression (leads CM5 and CC5) was unaltered. In a second group of 17 patients where the basal tests were performed in the afternoon and the placebo tests in the morning, heart rate and ST segment were found to be reproducible but there was a significant difference in exercise time: 5.7 (+/- 0.7) min for the basal test and 8.3 (+/- 0.5) min for the placebo test (P less than 0.001); and of the 1 mm ST depression time: 2.7 (+/- 0.4) min for the basal test, and 5.4 (+/- 0.5) min for the placebo test (P less than 0.001). We conclude that exercise tests done under standardised conditions in the morning are highly reproducible in patients with chronic stable angina and therefore provide a valuable test for the evaluation of antianginal drugs.

Aged↗
PubMed1984

Intravenous nicardipine in patients with chronic heart failure: a nuclear stethoscope study.

The effects of intravenous nicardipine (10 mg) on some aspects of left ventricular function have been studied with a radioisotope method in 10 male patients in chronic heart failure (NYHA Class II and III). Blood pressure (mean +/- s.d.) fell from 133 +/- 26/86 +/- 11 mm Hg to 103 +/- 22/69 +/- 13. Heart rate rose from 67 +/- 9 beats per minute to 85 +/- 10. Left ventricular ejection fraction rose from 31 +/- 7% to 38 +/- 6% and relative cardiac output from 24 +/- 9 to 41 +/- 11 (P less than 0.001 in all cases). This suggests that nicardipine has a potent vasodilator effect which results in increased left ventricular pumping activity in patients with mild to moderate heart failure.

Adult↗
PubMed1983

Dermal necrosis and chromosome Iq abnormality in a man with a familial myeloproliferative disorder.

A 33 year old man, with pre-existing psoriasis and a family history of multiple occurrence of acute myeloid leukemia and other myeloproliferative disorders, developed steroid-responsive ulcerating skin lesions, pancytopenia, marrow hypoplasia, hyperglobulinemia and polyarthritis. An abnormal karyotype (47,XY + i(1q] was detected in the bone marrow, and comparison with a case previously reported by Lee et al. Suggested that this abnormality may be significant. His sister, who developed chronic leucocytoclastic vasculitis, had pre-existing psoriasis, variable mild leucopenia and marrow dysplasia. Review of available records of other affected family members documented the occurrence of steroid responsive pancytopenia, knee swelling and terminal lipoid pneumonia in a first cousin. Four other relatives died with acute myeloblastic leukemia and another died with myelofibrosis. Two healthy first degree relatives were subjected to laboratory investigations with essentially negative findings.

Adolescent↗
PubMed1978

Growth of Chaetomium cellulolyticum on Alkali-Pretreated Hardwood Sawdust Solids and Pretreatment Liquor.

The treatment of a hardwood sawdust with 1% NaOH solution at 121 degrees C dissolved 19.7% of the dry matter, mainly hemicellulose and lignin. Fermentation of the treated solids by Chaetomium cellulolyticum for 48 h gave a product containing 12.5% crude protein (total N x 6.25) on a dry weight basis. The in vitro rumen digestibility of the 48-h fermentation product was 30%, compared to 24% for the alkali-treated but unfermented sawdust. Growth was independent of sawdust particle size in the range 40 to 100 mesh. Fermentation of the pretreatment liquor gave a product containing up to 50% crude protein (dry weight basis) with an in vitro rumen digestibility of 65 to 76%. Approximately 6.7 g of crude protein was obtained from the treated solids and 2.2 g from the pretreatment liquor per 100 g of sawdust treated. The product from the pretreatment liquor fermentation has potential as a high-protein animal feed supplement but could not be produced economically without an outlet for the relatively indigestible product from the solids fermentation. Growth on the pretreatment liquor was strongly pH dependent; there was a considerable increase in the lag phase when the pH was lowered from 7.5 to 5.2. This effect appears to be due to an inhibitor whose toxicity is reduced at high pH.

Journal Article↗
PubMed1977

SCP production by Chaetomium cellulolyticum, a new thermotolerant cellulolytic fungus.

Chaetomium cellulolyticum, a newly isolated cellulolytic fungus, showed 50-100% faster growth rates and over 80% more final biomass-protein formation than Trichoderma viride, a well-known high cellulase-producing cellulolytic organism, when cultivated on Solka-floc (a purified, predominantly amorphorous form of cellulose) or partially delignified sawdust (consisting of a mixture of hardwoods) as the sole-carbon source in the fermentation media. However, in both cases, T, viride produced much higher quantities of free cellulases at faster rates and also degraded more substrate than C. cellulolyticum. It is concluded that the synthesis mechanisms and/or the nature of the cellulase complexes of the two types of organisms are quite different such taht C. cellulolyticum is more optimal for single-cell protein (SCP) production, while T. viride is more optimal for the production of extracellular cellulase. It was also found that the amino acid composition of C. cellulolyticum is generally better than that of T. viride and compares favorably with those of the FAO reference protein, alfalfa, and soya meal. In addition, preliminary feeding trials on rats have shown no adverse effects of the SCP produced by C. cellulolyticum fermentations.

Amino Acids↗