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At least 19 recordsLinked to original sources
PubMedDate not supplied

Quantitation of microbicidal activity of mononuclear phagocytes: an in vitro technique.

An in vitro assay technique was set up to determine the phagocytic and microbicidal activity of a monocyte-macrophage cell line using Candida species as test organisms. The norms were determined for the activity of peritoneal macrophages of rats (24.69 +/- 2.6% phagocytosis and 35.4 +/- 5.22% ICK) and human (27.89 +/- 3.63% phagocytosis and 50.91 +/- 6.3% ICK). The assay technique was used to test the degree of activation of macrophages induced by metronidazole, Tinospora cordifolia and Asparaqus racemousus and to compare their effects with a standard immunomodulator muramyl-dipeptide. All the three test agents increased the phagocytic and killing capacity of macrophages in a dose dependent manner upto a certain dose, beyond which either these activities were found to have plateaued or decreased. The optimal doses for MDP, Metronidazole, Asparagus racemosus and Tinospora cordifolia were found to be 100 micrograms, 300 mg/kg, 200 mg/kg and 100 mg/kg respectively. Patients with cirrhosis were screened for defects in monocyte function. The depressed monocyte function (20.58 +/- 5% phago and 41.24 +/- 12.19% ICK; P < 0.05) was observed indicating a compromised host defense. The utility of this candidicidal assay in experimental and clinical studies is discussed.

Adult↗
PubMed1997

Comparison of in situ and in vitro techniques for measuring ruminal degradation of animal by-product proteins.

Ruminally undegraded protein (RUP) values of blood meal (n = 2), hydrolyzed feather meal (n = 2), fish meal (n = 2), meat and bone meal, and soybean meal were estimated using an in situ method, an inhibitor in vitro method, and an inhibitor in vitro technique applying Michaelis-Menten saturation kinetics. Degradation rates for in situ and inhibitor in vitro methods were calculated by regression of the natural log of the proportion of crude protein (CP) remaining undegraded versus time. Nonlinear regression analysis of the integrated Michaelis-Menten equation was used to determine maximum velocity, the Michaelis constant, and degradation rate (the ratio of maximum velocity to the Michaelis constant). A ruminal passage rate of 0.06/h was assumed in the calculation of RUP. The in situ and inhibitor in vitro techniques yielded similar estimates of ruminal degradation. Mean RUP estimated for soybean meal, blood meal, hydrolyzed feather meal, fish meal, and meat and bone meal were, respectively, 28.6, 86.0, 77.4, 52.9, and 52.6% of CP by the in situ method and 26.4, 86.1, 76.0, 59.6, and 49.5% of CP by the inhibitor in vitro technique. The Michaelis-Menten inhibitor in vitro technique yielded more rapid CP degradation rates and decreased estimates of RUP. The inhibitor in vitro method required less time and labor than did the other two techniques to estimate the RUP values of animal by-product proteins. Results from in vitro incubations with pepsin.HCl suggested that low postruminal digestibility of hydrolyzed feather meal may impair its value as a source of RUP.

Animals↗
PubMedDate not supplied

Cell-mediated immunity in healthy and uremic adults assessed by in vivo and in vitro techniques. Validation of delayed hypersensitivity skin testing.

Cell-mediated immunocompetence was assessed in 16 healthy and 10 uremic subjects by "in vivo" and "in vitro" techniques, simultaneously. PHA-induced lymphocyte transformation, Multitest and classical skin testing with a panel of 7 antigens have been used. Similar cutaneous delayed-type hypersensitivity (DTH) results were obtained when using either Multitest or the classical panel, both in healthy subjects (R = 0.66) and in uremic patients (R = 0.61). The results were the same for both the total scores and the number of positive responses per subject. The two DTH methods were of similar accuracy in the evaluation of normal DTH responses and hypoergy in both populations but the sensitivity in detecting anergy among the uremics was higher for the classical panel (80%) than for Multitest (60%). However, no method proved to be more prone to classify a healthy subject as anergic. Anergy was more frequent among uremic patients both with Multitest (60%) and the conventional panel (80%) but was unusual among healthy controls (6.3% and 7.1%, respectively) (p less than 0.0001 for both). Depressed DTH reactivity in uremia was correlated with longer blood transfusion-free intervals (p less than 0.05) and influenced by the duration of haemodyalisis and the number of blood transfusions. Similar CMI impairment rates were found in uremic patients with Multitest (76.9%), the classical panel (63.8%) and "in vitro" techniques (63.7%). Therefore, cutaneous DTH testing proved to be a useful mean of evaluating CMI. Moreover, the high cost and technical complexity of "in vitro" techniques are major drawbacks against their use and strenghthen the role of DTH skin testing as a useful clinical tool to measure CMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Evaluation of the efficacy of d-penicillamine and trientine as copper chelators using an in vitro technique involving ovine red blood cells.

An in vitro technique for haemolysing ovine red blood cells with copper sulphate was standardized to induce c 50% haemolysis with 0.5 mM CuSO4 after incubation for 14 h at 38 degrees C. This technique was then applied to test the efficacy of trientine and d-penicillamine in preventing haemolysis. Trientine concentrations of 0.5; 1.0 and 1.5 mM were found to be the most effective (P < 0.05) in reducing copper-induced haemolysis. One and 1.5 mM concentrations of d-penicillamine were also effective (P < 0.05), but in this experiment a 0.5 mM concentration failed to protect the erythrocytes.

Animals↗
PubMed1987

The PIT method: an automated in vitro technique for drug toxicity testing.

An automated in vitro technique for drug toxicity testing is described. Human tumor cells were cultured for 2 days in 96-well microtiter plates before the addition of serial dilutions of drugs. At day 5 the cultures were terminated by the addition of a solution containing propidium iodide, ink and triton X-100 (PIT). Triton X-100 lysed all cells, which were subsequently stained by the DNA specific fluorescing propidium iodide. The ink effectively quenched all background fluorescence. The plates were read on a computer controlled automated microscope with a photomultiplier. The results showed a linear relationship between cell number and fluorescence intensity. Reproducible dose-response curves were obtained for 6 drugs tested. A computer program calculated ID50 values, making use of adequate growth and no-growth controls.

Antineoplastic Agents↗
PubMed1997

Impact of the in vitro technique used on the cytogenetic patterns in pleomorphic adenomas.

The cytogenetic observations in 97 new cases of pleomorphic adenomas are reported. They were all studied by in vitro technique using enzymatic pretreatment of the explanted material. The results, together with 26 previously reported cases studied by the same method (series II), were compared with a group of 130 adenomas (series I) investigated in cultures of only mechanically dispersed material. The results showed that in series II there was a substantial reduction of normal stemlines, an increase of cases with t(3;8)(p21;q12) and, in particular, of those with other 8q12 involvement. There was a similar frequency of cases with 12q13-15 aberrations in both series whereas, in series II, there was a moderate increase of the cases with "unique" abnormal stemlines. In comparison the German material, comprising 220 cases also studied by the enzymatic method, revealed a much higher frequency of cases with a normal stemline and a much lower frequency of adenomas with 8q12-involvement and of cases with unique stemlines. The results emphasize the need and importance of a meticulous documentation of all details of the in vitro technique used, for instance: explantation methods, composition of media, growth periods in vitro, and methods of harvest.

Adenoma, Pleomorphic↗
PubMed1984

Haemostatometer: a new in vitro technique for assessing haemostatic activity of blood.

An in vitro technique to study haemostasis has been devised (the "haemostatometer") and investigated in detail. Anticoagulated blood is perfused through a teflon tube through which two holes are punched with a needle. The perfusion pressure is recorded continuously: the pressure drop after punching reflects "bleeding", and the pressure recovery indicates the pattern of the haemostatic plug formation. Platelets play the major role in the mechanism, but red cells are also necessary to arrest the bleeding. Fibrin formation does occur and contributes to the stabilisation of the haemostatic plug. Induced platelet dysfunction or bleeding diathesis due to platelet function defect can be detected by this technique. Except for the absence of any contribution from the blood vessel wall, this model provides a close ex vivo approximation to the complex process of haemostasis and possibly also thrombus formation.

Adenosine Triphosphate↗
PubMed1995

An in vitro technique for the rapid determination of drug entry into breast milk.

1. A simple in vitro technique that predicts drug transfer into breast milk is described. 2. Drugs of differing physical and chemical characteristics were tested. 3. The technique provides an experimental system for studying plasma to milk transfer with changing milk composition. 4. A mechanism proposing a role of milk proteins in controlling drug entry into milk is discussed.

Fats↗
PubMed1993

A novel in vitro technique to study extrinsic neural control of rabbit colonic muscle and epithelial function.

A novel in vitro technique capable of simultaneously measuring distal colonic epithelial potential difference and muscle contraction is described. Under basal conditions, oscillations in both muscle tone and potential difference were observed. Pelvic nerve stimulation was shown to evoke strong "duration" contractile responses in both the longitudinal and circular muscle layers. Additionally, tonic changes in potential difference extending beyond the train of stimuli were observed, suggesting for the first time that colonic ion transport may be influenced by the pelvic nerves. However, it was unclear whether these were direct effects or indirect actions resulting from muscle contractions causing mechanical stimulation of nerves of the submucosal plexus. Lumbar colonic nerve stimulation inhibited spontaneous contractile activity and reduced basal tone in both muscle layers. However, there was no consistent effect of sympathetic nerve stimulation on transepithelial potential difference. Each of the muscle and epithelial effects of sympathetic nerve stimulation was mimicked by exogenous norepinephrine. Based on these data, it is concluded that colonic function is strongly influenced by the extrinsic innervation. Furthermore, relatively long-term modulation of epithelial function can be achieved by short bursts of pelvic nerve activity.

Acetylcholine↗
PubMed2000

Applications of immobilized stationary-phase liquid chromatography: a potential in vitro technique.

Immobilized artificial-membrane chromatography is a potential in vitro technique for determining lipophilicity and studying drug transport and membrane interactions. It is reproducible, efficient and simple. Several other and newer applications of immobilized stationary-phase liquid chromatography have been reported, including the purification of membrane proteins, the synthesis of biomolecules and the simultaneous determination of enzyme activity and enantioselectivity. This article describes the immobilized artificial-membrane concept and provides an overview of the applications, advantages and limitations, in general, of immobilized stationary-phase chromatography.

Journal Article↗
PubMed2004

How in vitro techniques have increased our understanding of uveal melanoma cellular biology.

The past decade has seen a rapid increase in powerful in vitro techniques allowing for the specific study of the biologic properties of tumours. In this review we discuss the role of in vitro studies in providing insight into the biologic mechanisms involved in uveal melanoma. We also review the basis of these studies for the development of adjuvant therapies to aid in the treatment of systemic disease in patients with uveal melanoma.

Biology↗
PubMed1996

In vitro techniques for studying drug metabolism.

A considerable amount of information has been obtained about human enzymes involved in drug metabolism. Cytochrome P450 is presented as a paradigm in order to illustrate the experimental techniques now available. In vitro assays can be done with tissue slices, microsomes, or even short-term cell cultures. In addition, recombinant enzymes can be produced in a variety of different vector systems. Information about catalytic selectivity regarding new drugs can be obtained, as well as important information about potential drug-drug interactions and bioavailability. Such studies play a role in the drug development process as well as metabolism and safety assessment.

Animals↗
PubMed1995

Assessments of thrombogenicity by three in vitro techniques. Student Research Award in the Undergraduate, Master Candidate, or Health Science Degree Candidate Category, 21st annual meeting of the Society for Biomaterials, San Francisco, CA, March 18-22, 1995.

This study assessed three in vitro techniques designed to measure the thrombogenicity of vascular grafts. All techniques immersed vascular grafts in rotating blood. In the gravimetric analysis, the weight of adherent thrombi was recorded at 2 min intervals for 20 min. In the torque analysis, a microviscometer continuously recorded the amount of torque developed as the graft rotated for 20 min. In the thrombin analysis, the blood sample was analyzed for fibrinopeptide A production indicating fibrinogen cleavage. Expanded polytetrafluoroethylene grafts were treated by removal of air nuclei (denucleation), binding of heparin, or binding of polyethylene oxide (PEO). The gravimetric analysis determined that the time at which each group experienced clot initiation was as follows: control after 6 min, denucleation after 14 min, heparin after 18 min, and PEO after 10 min. Similarly, in the torque analysis all treatment groups significantly delayed the initial increase in torque from 8.0 min for control to 12.5 min for denucleation (P < .01), > 20 min for heparin (P < .01), and 12 min for PEO (p < .05). The thrombin analysis determined that coagulation activity was reduced relative to control at 12 min with the denucleation group (P < .05) and heparin group (P < .01) and at 18 min with all treatment groups (P < .01). The similarity of results among the techniques increases confidence that each measurement accurately predicts in vitro thrombogenicity.

Awards and Prizes↗
PubMed1977

Oxygen affinity of duck blood determined by in vivo and in vitro technique.

Half saturation partial pressure of O2,P50, was determined in domestic Muscovy ducks (Cairina moschata) both by in vivo and in vitro techniques. For in vivo determination, blood samples were drawn from the anesthetized, artificially ventilated animals and analyzed both for O2 content, Co2, and O2 partial pressure, Po2. O2 capacity was detemined in arterial samples during hyperoxic ventilation (arterial Po2 about 180 torr). P50 was calculated from measurements in venous blood samples (O2 saturation near 50%). For in vitro determinations, Co2 was measured in blood samples equilibrated with Po2 close to P50. No significant difference was found between P50 values determined by both techniques. At 41 C and pH 7.50, P50 averaged 41.7 torr when analyzed by in vivo technique and 41.4 torr when determined in vitro. The variability between animals was less than 1 torr (SD) and could be explained by the experimental error. The partially discordant literature data on P50 of duck blood are reviewed and critically discussed.

Animals↗
PubMed1989

Comparison of three in vitro techniques to estimate benzimidazole resistance in Haemonchus contortus of sheep.

Three in vitro assays to detect benzimidazole resistance, namely, the egg-hatch assay, tubulin-binding assay, and a larval-development assay, were evaluated by estimating the level of benzimidazole resistance in three field isolates of Haemonchus contortus compared with a susceptible reference strain. Comparisons were also made with estimates of benzimidazole resistance of the three field strains obtained from an in vivo controlled anthelmintic efficacy test. All three in vitro tests showed similar, consistent results which also suggested greater sensitivity than the in vivo assay. These results indicate that selection of an in vitro technique to determine benzimidazole resistance should therefore be based on considerations other than precision, such as technical expertise, availability of equipment, cost and speed in which diagnosis is required.

Analysis of Variance↗
PubMed1989

In vitro technique for studying garter snake (Thamnophis sp.) development.

Garter snake (Thamnophis sp.) embryos of different embryonic ages were explanted from pregnant females and grown in vitro for up to 35 days. The culture medium consisted of Eagle's Minimum Essential Medium with various organic and inorganic supplements and antibiotics. Cultured embryos were injected with tritiated thymidine, sacrificed, and processed for autoradiographic examination. The in vitro technique allowed direct visualization of external morphologic changes over time, which followed a timetable similar to that of embryos growing in vivo. This technique also allowed easier manipulation of embryos for determination of embryonic stage and for injection of tritiated thymidine. This is the first report of long-term culture of snake embryos which adds to the limited number of reptilian embryos that have been studied in vitro.

Animals↗
PubMed2004

An in-vitro technique for assessment of thrombogenicity in mechanical prosthetic cardiac valves: evaluation with a range of valve types.

BACKGROUND AND AIM OF THE STUDY: An in-vitro technique has been developed to assess the flow-induced thrombosis of artificial heart valves, using renneted milk as a blood analog. Previous studies have demonstrated similarities between the clotting of blood and milk on both microscopic and macroscopic scales. The study aim was to further validate the milk test by comparing the locations of milk clot to those of thrombus formation on a wide selection of mechanical heart valves. METHODS: Nine different valves were tested in the aortic position of a model heart chamber in the Edinburgh milk rig. These included caged-ball valves (Starr-Edwards silastic ball with bare struts and metal ball with cloth-covered struts), tilting-disc valves (Björk-Shiley Standard, Björk-Shiley Monostrut, Medtronic-Hall, and Ultracor), and bileaflet valves (St. Jude Medical, Edwards-Duromedics, and CarboMedics). Renneted milk was pumped through the valves for 30 min at 2 l/min, 70 bpm pulsatile flow. After each run, valves were photographed for comparison with documented sites of thrombosis. RESULTS: All valves developed milk clot in specific, reproducible locations when run in the aortic position. Milk clot was found on the struts of caged-ball valves and tilting-disc valves, and around the hinge mechanism of the bileaflet valves. This compared favorably to documented cases of thrombosis in vivo. CONCLUSION: Renneted milk may be used to model flow-induced thrombus formation and to predict the thrombogenic sites of mechanical heart valves. Whilst it is not suggested that milk mimics the entire blood coagulation cascade, these results indicate that such behavior may not be necessary for predicting fluid mechanically induced clotting.

Animals↗