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Biomedical subjects

A R Smith

Publications and source records attributed to A R Smith.

At least 145 records · Page 8Linked to original sources
PubMed1984

Fluorocarbons and the microcirculation.

A short discussion of oxygen transport and delivery by fluorocarbon containing blood substitutes is presented. Those physical properties of the preparations that would tend to cause improvement in oxygenation in areas of damaged or impeded microcirculation are also discussed. A number of studies carried out at the Erasmus University, Rotterdam have demonstrated certain important characteristics of fluorocarbons with respect to tissue oxygenation. In the first instance, it has been demonstrated that extracorporal perfusion with Fluosol-DA 20% can maintain oxygenation and viability of isolated extremities for periods of up to 48 hours. Secondly it has been shown that the preparation can indeed penetrate compromised capillary beds, its low viscosity enabling it to travel along collateral perfusion pathways and to provide oxygenation of areas of ischaemic hypoxia. The low particle of the emulsion may, in combination with the low viscosity of the product, contribute to the re-establishment of perfusion in areas of circulatory arrest. The clinical implications of the above findings are numerous and wide spread. The importance of Fluosol in maintaining and improving micro-circulatory oxygenation should not be underestimated.

Animals↗
PubMed1984

Rapid purification of 2,4-dichlorophenol hydroxylase by biospecific desorption from 10-carboxydecylamino-sepharose.

10-Carboxydecylamino-Sepharose, which bears a mixture of ionic and aliphatic substituent groups, adsorbs 2,4-dichlorophenol hydroxylase from Acinetobacter in a non-biospecific manner. The enzyme has been specifically desorbed by its substrate, 2,4-dichlorophenol, giving a 42-fold purification (to greater than 90% purity) in a single step. The enzyme contained 3.1 moles of FAD per mole and displayed a catalytic constant of 14.7 s(-1). Mixed-function adsorbents probably have wide applicability for biospecific desorption of proteins. The present report indicates that they may be useful in the purification of aromatic hydroxylases bearing flavin prosthetic groups that readily dissociate in conventional purification procedures employing conditions of high ionic strength.

Acinetobacter↗
PubMed1983

Bacterial endotoxin in blood of dysgalactic sows in relation to microbial status of uterus, milk, and intestine.

Clinical cases of lactation failure in sows from 6 swine herds in Illinois were investigated for the presence of bacterial endotoxins in blood and the concurrent microbial status of uterus, milk, and intestine. Twenty-five affected sows were compared with 13 contemporary healthy sows (controls) in the same herds. A higher prevalence of bacterial endotoxin in blood of affected sows than in the controls, although not statistically significant, supported earlier theories of endotoxin involvement in the disease. Further, a positive relationship was noticed between prevalence of solely gram-negative bacteria in ileum and milk and development of dysgalactia and endotoxemia. No such relationship was found for bacterial isolates from the uterus, suggesting lack of association between lactation failure and metritis.

Animals↗
PubMed1983

Phagocytosis in the uterus: A review.

Phagocytosis is an important non-specific defense mechanism. Uterine phagocytosis is reviewed emphasizing factors which may alter the uterine phagocytic responses including the estrous cycle, pregnancy and the puerperium, and the presence of an intrauterine device. Implications of phagocytosis in therapy of and recovery from intrauterine infections are considered.

Journal Article↗
PubMed1983

Biological effects of pion therapy beams: I. Cultured cells.

The results of cell killing by pion beams of different peak widths, ranges and sizes used in therapy are reported. Cultured hamster cells (V79) suspended in gelatin were used. The results indicate that: 1) there are no significant differences in cell-killing between pion beams of different ranges but of the same peak width; 2) there is a slight decrease in biological effectiveness with increasing peak width; and 3) the range-modulation functions used to produce uniform cell-killing are satisfactory for intermediate-range pion beams, but slight corrections may be required for shorter- and longer-range pion beams.

Animals↗
PubMed1983

Clinical application of transcutaneous oxygen measurements in replantation surgery and free tissue transfer.

In 65 replantations and 18 free tissue transfers (6 toe-to-thumb and 12 free flaps) transcutaneous oxygen levels were used as a postoperative monitoring system of the microcirculation. In successful replants and successful free tissue transfers an identical pattern of oxygen levels was observed. In failing replants or free tissue transfer, PO2 levels react immediately to changes in microcirculation and these changes in PO2 appear several hours earlier than the clinical symptoms or changes in temperature. This enables salvage operations after circulatory failure caused by thrombosis to be performed before irreversible tissue damage occurs.

Adult↗
PubMed1983

Quantitative oxygen measurements before and after intravascular guanethidine blocks.

In 11 patients oxygen pressure was measured transcutaneously before and after treatment with regional intravascular sympathetic blocks in extremities with pain, impairment of function, and/or dystrophy. In 50 normal individuals PO2 levels were determined in the hand. All patients showed lower than normal values before treatment. Subjective complaints were registered by means of a questionnaire before and after treatment. Improvement of PO2 levels was observed after treatment in eight out of 11 patients while complaints disappeared. Three out of 11 patients showed no improvement of PO2 levels or any lessening of complaints. Control PO2 values in the contralateral limbs stayed on the same level as before treatment in all patients. From the results in this article it can be stated that TcPO2 measurements seem to be helpful in (1) evaluating the pretreatment microvascular state of the affected limb and (2) judging the efficacy of the block.

Adult↗
PubMed1983

Influence of the estrous cycle on selected biochemical and cytologic characteristics of milk of cows with subclinical mastitis.

The purpose in this experiment was to determine the relationship between subclinical mastitis and the estrous cycle. Subclinical mastitis was defined as a quarter in which milk had a somatic cell concentration greater than 500,000/ml and was bacteriologic culture-positive on 2 consecutive examinations. Normal quarters were defined as quarters from which milk had a somatic cell concentration less than 500,000/ml and was bacteriologic culture-negative on 2 consecutive examinations. Selected biochemical and cytologic characteristics of milk from 10 cows with subclinical mastitis were measured at 5-day intervals during the estrous cycle. Milk and blood progesterone concentrations were determined. Analysis of variance of dependent variables was performed, using a model with the following factors: cows, treatments, days of estrous cycle, and interaction of treatment with day of the estrous cycle. Treatment consisted of comparison of normal and subclinically mastitic quarters. Clinical signs of mastitis tended to occur more often during estrus (days 0 and 20) than during diestrus (day 10). Day of the estrous cycle was a significant source of variation for bovine serum albumin concentrations in milk. Somatic cell concentrations, electrical conductivity, milk bacterial concentrations, and log10 milk bacterial concentrations did not vary significantly during days of the estrous cycle. A significant treatment-by-day interaction occurred for milk progesterone concentrations; blood progesterone concentrations were not similarly affected. Milk progesterone concentrations for mastitic and normal quarters were similar at estrus (days 0 and 20) and metestrus (day 5). Milk progesterone concentrations for mastitic quarters were significantly decreased on day 15 of the estrous cycle, compared with values from normal quarters.

Analysis of Variance↗
PubMed1982

Directional Ca2+ effect on stimulation of mucin secretion from chicken trachea in vitro.

Chicken tracheal mucosa in vitro transported and incorporated radioactive precursors into mucins, which were secreted at a steady rate into the tracheal lumen. Secretion of mucins labelled with (35)S and (3)H after pulse-labelling of the mucosal layer with Na(2) (35)SO(4) and d-[1-(3)H]glucosamine as precursors was an energy-dependent process, as it was strongly inhibited by the action of respiratory-chain inhibitors, an uncoupler of oxidative phosphorylation, a metabolic blocker and a temperature shift from 41 degrees C to 5 degrees C. On the other hand, both cholinergic and parasympathomimetic agents considerably increased the secretion of dual-radiolabelled mucins when applied on the submucosal side of the trachea. The effect of Ca(2+) was directional, since only high submucosal (3.6 or 18mm) or low luminal (zero or 0.18mm) Ca(2+) massively enhanced the secretion of radiolabelled mucin compared with the mucin output measured under physiological Ca(2+) conditions (1.8mm). Whereas application of ionophore A23187 on either side of the trachea significantly increased mucin output, its presence in the appropriate tracheal compartment and under appropriate Ca(2+) conditions further accentuated the output of radiolabelled mucins. Addition of acetylcholine under appropriate conditions also had an additive effect on the Ca(2+)-stimulated secretion of mucins. Ca(2+) stimulation of mucin secretion appears to be dependent on the metabolic integrity of the mucosal cells. Mucins secreted in response to high submucosal and low luminal [Ca(2+)] appear to consist of a number of different types of glycoproteins, as judged from their ion-exchange-chromatographic behaviour.

Animals↗
PubMed1982

Diagnosis and treatment of acute mastitis in a large dairy herd.

In a 270-cow dairy herd, milk samples from all cows with acute mastitis were cultured during a 12-month period. Of 119 isolates (from 166 quarters), 49% were gram-positive organisms, 39% were gram-negative organisms, and 12% were yeasts. Of all samples from cows with acute mastitis, 40% failed to produce colonies on culture media. Recovery of the common gram-positive pathogens, Staphylococcus aureus (11% of isolations) and Streptococcus agalactiae (1% of isolations), was rather low. However, S epidermidis (14% of isolations) and streptococci other than Str agalactiae (9% of isolations) were recovered more frequently than expected, particularly in recently calved cows. Coliform organisms accounted for 35% of the total isolates and were the single most important cause of acute mastitis. Of 42 cows with coliform mastitis, 6 died despite intensive antibiotic and electrolyte therapy. There was no death loss among cows with mastitis caused by gram-positive organisms. Antimicrobial susceptibilities of 95 isolates to 11 antimicrobials was determined by standardized methods. Organisms were most often susceptible to chloramphenicol, cephalothin, and gentamicin. A treatment regimen consisting primarily of oxytetracycline and/or sulfonamides systemically in conjunction with intramammary infusions of cephapirin was evaluated. Treatment response in 37 quarters was determined by culturing before treatment and at 4 or more days after treatment. Of 23 quarters initially culture-positive, 22 were negative on reculture. Treatment response appeared to agree with the results of the susceptibility testing.

Acute Disease↗
PubMed1982

The purification and properties of 2,4-dichlorophenol hydroxylase from a strain of Acinetobacter species.

1. 2,4-Dichlorophenol hydroxylase has been purified 13-fold from Acinetobacter grown on 2,4-dichlorophenoxyacetic acid as sole carbon source. The enzyme was estimated to be 80-90% pure by electrophoresis. 2. The enzyme has a relative molecular mass of about 240 000 and consists of four subunits of identical size. 3. The enzyme contains FAD as the prosthetic group. FAD could not be replaced by riboflavin or FMN in reconstituting active enzyme from apoenzyme. 4. The reaction catalysed is an NADPH-dependent hydroxylation of 2,4-dichlorophenol with the formation of 3,5-dichlorocatechol as product. The reaction stoichiometry is typical of a monooxygenase with an external electron donor. NADPH is the preferred reduced pyridine nucleotide substrate but the enzyme can function with NADH. 5. The enzyme possesses broad effector specificity. In addition to 2,4-dichlorophenol, 4-chlorophenol and 4-chloro-2-methylphenol are true substrates for the enzyme. A number of 'non-substrate effectors' has been found. 6. The enzyme is sensitive to thiol-inhibiting reagents.

Acinetobacter↗