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Biomedical subjects

D H Lewis

Publications and source records attributed to D H Lewis.

At least 127 records · Page 7Linked to original sources
PubMed1979

Activation of the kallikrein-kinin system in bullet wounding.

Anesthetized pigs were wounded in the thigh with a spherical missile at an impact velocity of 1500 m/sec. Arterial blood samples were taken before injury and at frequent intervals up to 12 hours after injury. Unbound (free) and total kallikrein (kallikrein + prekallikrein) were analyzed with a chromogenic substrate (S-2302, Kabi, Sweden) in which enzyme activity is determined spectrophotometrically by the development of a yellow colour. The results indicate an activation of the kallikrein-kinin system in bullet wounding, the significance of which remains to be determined.

Animals↗
PubMed1979

Use of a new bead microcarrier for the culture of anchorage dependent cells in pseudo suspension.

The use of cross linked dextran beads having a surface charge produced using the method of Levine et al. (1976) is described. The new microcarriers require no pretreatment, and may be used at greater concentrations than those originally described by van Wezel (1967). Microcarrier cultures are initiated by inoculating cells into a stirred suspension of beads in culture medium. The cells spread over the surfaces of the beads, and follow typical growth curves. They may be harvested by conventional trypsinisation, and separated from denuded beads using a sintered glass filter. The beads may be regenerated and re-used. The beads have been found to be suitable for the growth of a variety of fibroblastoic cell types. It is suggested that the microcarriers are suited for bulk virus or metabolitic production from anchorage dependent cells.

Animals↗
PubMed1978

In vivo lung uptake of lidocaine in pigs.

A mixture of 14C-labelled lidocaine and indocyanine green dye (IG) (Cardiogreen) was injected as a bolus into the pulmonary artery in pigs (15-25 kg). Time-concentration curves for both substances were constructed from 20s blood samples taken from the common carotid artery for approximately 20s. The extraction of lidocaine in each sample and the 95% first passage uptake (FPU) were calculated, assuming that IG is inert with respect to the lung and that it remains within the vascular compartment. The IG curves were also used to calculate cardiac output. The acid-base status and arterial blood pressure or ECG were also followed. Each animal was given two injections. When 0.5 mg/kg b.w. lidocaine was injected, FPU was 41 +/- 3%; at a dose of 2 mg/kg b.w., FPU was 28 +/- 3% (P less than 0.05). The initial extraction during the first 2 s after appearance of the substances was approximately 80%. This level declined with subsequent samples, and the decline was equally rapid at both dose levels.

Anesthesia, Intravenous↗
PubMed1978

The local hemodynamic effects of operation in a bloodless field.

Skeletal muscle blood flow and transport function were investigated in 25 patients operated on for a knee injury in a bloodless field. With a double-isotope-clearance technique, measurements were carried out in the operated leg immediately after re-establishment of blood flow, and 1-2 days postoperatively in both the operated and the non-operated leg. A significant increase in blood flow and transport function was registered immediately after release of the tourniquet. The initial maximal hyperemic flow and transport responses were inversely related to the duration of the occlusion. The peak of the blood flow response was more marked and somewhat earlier in the patients with a short duration of occlusion (less than or equal to 60 min) than in those with longer occlusions. 9 of 16 operated legs showed a maximal transport function 1-2 days postoperatively. Peripheral vascular resistance decreased after re-establishment of blood flow. The blood flow in the non-operated leg showed no changes after release of the tourniquet in the operated leg.

Adult↗
PubMed1978

Comparison of selected diagnostic tests for detection of motile Aeromonas septicemia in fish.

Cultural isolation, slide agglutination (SA), tube agglutination (TA), microagglutination (MA), and fluorescent antibody (FA) techniqes were compared as methods for detecting motile aeromonas septicemia in channel catfish (Ictalurus punctatus). Tests were conducted on naturally infected fish from feral populations and commercial sources, as well as on fish which were experimentally infected with a virulent culture of Aeromonas hydrophila. Increased levels of specific serum agglutinins to A hydrophila were demonstrable only in fish from whose blood the organism could be recovered. It was concluded that the SA procedure was an effective diagnostic test which would be most useful under field conditions. Under laboratory conditions, the TA, MA, and FA procedures were found to be equally effective in detecting the level of serum agglutinins to A hydrophila. The FA procedure, however, was more sensitive than any of the agglutination procedures and could be performed in less time than TA or MA.

Aeromonas↗
PubMed1977

The resistance of intracellular Leishmania parasites to digestion by lysosomal enzymes.

Infections of Leishmania mexicana in cultured normal mouse peritoneal macrophages show different morphological features depending on whether the parasites invade as promastigote or amastigote forms. Infections derived from promastigote invasion are characterized by parasitophorous vacuoles which develop slowly, and acquire only modest proportions. In contrast, the organisms in amastigote-derived infections lie within parasitophorous vacuoles which develop more rapidly, and attain a much greater size. From observation of promastigotes of different species of Leishmania, it appeared that survival subsequent to endocytosis by normal macrophages depends on the parasites' rapid transformation to the amastigote form. Activation of the macrophage population produced an enhanced parasiticidal effect only against incompletely transformed Leishmania promastigotes. Electron microscope investigations, involving enzyme histochemistry and lysosome labelling techniques, indicate that intracellular Leishmania avoid digestion by interfering with the activity of lysosomal enzymes that are freely delivered to the parasitophorous vacuole. It is proposed that this ability is acquired on transformation to the amastigote, and incidentally induces fluid distension of the parasitophorous vacuole through phenomena recently described by other workers.

Acid Phosphatase↗
PubMed1977

Early biochemical and hemodynamic changes after operation in a bloodless field.

Biochemical and hemodynamic changes during and after operation in a bloodless field have been investigated in 13 patients. The patients were athletes between the age of 21 and 38 years who were healthy except for an inveterate ligament injury of the knee joint. Capillary blood flow in the tibialis anterior muscle was measured by the radioactive-Xenon-clearance technique. Fine plastic catheters for blood sampling were inserted into both femoral veins and into one radial artery. A significant increase in blood flow occurred immediately after release of the occlusion. After release of the tourniquet, there was a marked decrease in pH both in the venous blood draining the operated leg and in the arterial blood. 40 min after release of the tourniquet, there was still a significant decrease in base excess. An increase of venous pO2 in the blood draining the operated leg was observed after re-establishment of blood flow. The estimated oxygen consumption was increased in the operated leg the first 10 min after tourniquet release.

Acid-Base Equilibrium↗
PubMed1977

Circulatory disturbances following transient soft tissue compression trauma.

Circulatory changes following standardized compression trauma to the hind leg in dogs were evaluated using an electromagnetic flow meter and repeated angiography. A transient increase of flow to the injured limb and within the traumatized region was observed. Good agreement was found between the electromagnetic flow recordings and estimates of relative changes in flow by the angiographic method.

Angiography↗