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Biomedical subjects

A Kolin

Publications and source records attributed to A Kolin.

At least 37 records · Page 2Linked to original sources
PubMed1985

Recurrent acute otitis media--prophylactic penicillin treatment: a prospective study. Part I.

Recurrent acute otitis media (RAOM) is a distressing clinical manifestation of middle ear pathology, mainly expressed in the first two years of life. In this controlled study, prophylactic treatment by phenoxymethyl penicillin reduced significantly the frequency of RAOM in 60 children, as compared to 48 children who received a short ampicillin course only on the occasion of an acute otitis media episode. The importance of breastfeeding, age at initial episode, the type of treatment given and the pertinent literature is discussed. A working hypothesis of this prophylactic treatment is suggested.

Acute Disease↗
PubMed1983

Lymphomatoid granulomatosis involving the gastrointestinal tract. Two case reports and a review of the literature.

Two cases of lymphomatoid granulomatosis affecting the gastrointestinal tract in the form of gastric ulceration and intestinal perforation are described. This rare presentation of lymphomatoid granulomatosis is discussed in the context of previous reviews of the disease, and it is suggested that clinically overt gastrointestinal involvement represents a very poor prognostic indicator in this condition.

Adult↗
PubMed1983

Tumour rejection in immunized guinea-pigs.

The morphological aspect of the antineoplastic defence mechanism was studied in Sewall-Wright strain 13 guinea pigs using isogeneic line 2 hepatoma cells. When these tumour cells were injected i.p. into isogeneic hosts, they grew rapidly and always killed their hosts within 8 weeks. An intradermal injection of line 2 hepatoma cells in strain 13 guinea-pigs 3 weeks before i.p. challenge with the same tumour cells protected such pre-immunized animals. While the intradermal inoculum failed to grow, it conferred sufficient immunity to enable the host to reject the tumour after a short period of growth. This phenomenon showed immunological specificity since intradermal injection of allogeneic hepatoma cells did not offer this protection. By using sequential histological analysis in these preimmunized animals, we were able to identify 2 sets of cells migrating into and around tumour modules in relation to tumour cell death. Firstly, small numbers of small lymphocytes were observed at the earliest signs of tumour cell damage. They were most likely the effectors of antineoplastic defence mechanisms. Secondly, a variety of numerous inflammatory cells including macrophages were observed later when the tumour was necrotic, and these cells were considered to be present as a response to tumour cell death.

Animals↗
PubMed1982

Effects of antibodies to choriogonadotropin in malignant growth. I. Rat 3230 AC mammary adenocarcinoma.

To determine whether the in vivo production of antibodies against choriogonadotropin (CG) could modify the relationship between host and malignant growth, the effects of preimmunization with a conjugate of the beta-subunit of CG and tetanus toxoid (CG beta-tt) on the development and growth of lung metastasis following I.V. injection of R 3230 rat mammary adenocarcinoma cells into Fischer 344 female rats have been investigated. This neoplasm has been previously demonstrated to synthesize CG-like material. A test group of 70 animals and two matched control groups of 15 animals each were used. One of the control groups was untreated and the other received tetanus toxoid only. All the control animals had multiple lung foci of neoplastic cells ten days after seeding, as has been previously observed, and CG antibodies were undetectable. In contrast, a significant titer of anti-CG was found in all preimmunized animals. At the same time, the pretreated animals rarely had a few small neoplastic nodes in the entire lung sections at the standard 8--10 days post-seeding. The protective effects of preimmunization with CG beta-tt were further demonstrated by the animals living 20 days post-seeding, the absence of lung pathology in the ones killed thereafter, and by six animals that were left alive and have not shown any deterioration for more than six months after the administration of the cell suspension.

Adenocarcinoma↗
PubMed1982

Effects of antibodies to choriogonadotropin in malignant growth. II. Solid transplantable rat tumors.

We have studied the effects of preimmunization with a conjugate of beta-subunit of choriogonadotropin and tetanus toxoid (CG beta-tt) on the growth of the implanted R 3230 AC mammary adenocarcinoma (in Fischer 344 rats) and the implanted 5123 1-1 hepatoma (in Buffalo rats) after 20 days, in order to determine if the in vivo production of antibodies against CG could modify the relationship between host and malignant growth. The results obtained demonstrated that active immunization against CG retarded significantly (P less than 0.01) the growth of the two transplantable tumors. Anti-CG antibodies were also determined and constantly found in the sera of all the preimmunized rats of both strains while no antibodies to CG were found in the control animals.

Adenocarcinoma↗
PubMed1982

Observations of arterial and venous vasomotion with the absolute induction angiometer.

This paper provides biological illustrations of the applicability and mode of use of intravascular and perivascular absolute induction angiometers. Artifacts and limitations of the method as well as experimental precautions and calibration procedures are discussed. Tracing are presented to illustrate the capabilities of the method in recording pulsatile diameter changes in veins and arteries and to demonstrate its applicability to moving blood vessels as exemplified by the coronary arteries. Both intravascular and perivascular angiometry can detect diameter changes of a few micra in a vessel 1 cm in diameter. The intravascular angiometer is a resilient loop of fine bifilar wire which can be introduced into the blood vessel percutaneously via an angiographic catheter. A perivascular angiometer is an easily deformable loop made of a soft fine wire pair which is draped around a blood vessel and can thus be chronically implanted.

Animals↗
PubMed1980

Stem compensation of loop sensors for electromagnetic blood flow and vascular diameter measurement.

Accuracy of electromagnetic blood flow--and vascular diameter--measurements by means of intravascular loop probes in an extracorporeal alternating magnetic field can be impaired by an error signal induced in the probe stem. The standard method of removing this artifact by twisting the lead wires is difficult to implement in this case because the wires are bifilar and are made of highly resilient metals. The solution described here makes use of a hair pin loop incorporated within the probe stem in which an e.m.f. is induced that can be used to cancel the unwanted e.m.f. induced in the lead wires of the loop of the sensor. This scheme is applicable to simple loop probes as well as to orthogonal double-loop sensors.

Catheters, Indwelling↗
PubMed1980

Absolute induction angiometer.

The objective of this method is the continuous recording of vascular diameters and their measurement in absolute terms. This can be accomplished by percutaneously introduced intravascular sensors (IVS) or surgically implanted perivascular sensors (PVS). Both types of sensor are made of bifilar insulated wires forming a bifilar loop. One wire of the bifilar loop acts as a transformer primary inducing an electromotive force (EMF) in the secondary loop wire. The latter EMF is a measure of the vascular diameter. The IVS loop is made of resilient wire and is disposed across a vascular diameter in the central plane of a blood vessel. The sensitivity is such that phasic variations of a few micrometers in the diameter of a major blood vessel (such as the aorta or a coronary artery) can be measured and recorded. The surgically implanted perivascular loop sensor permits observation of vasomotion in a conscious, unrestrained animal. Both IVS and PVS permit observation of coronary vasomotion in the beating heart. Unlike the relative induction angiometer, the present device does not require an extracorporeal magnet.

Angiography↗
PubMed1978

Phasic registration of venous diameter changes in-situ with the induction angiometer.

The method of induction angiometry has been used for observation of active and passive venous vasomotion, without surgical exposure of the blood vessel. The diameter sensor is a resilient loop introduced into the vasculature through a fine No. 5 French (1 mm i.d.) angiographic catheter or a needle of comparable internal diameter. An extracorporeal a. c. magnet induces an electromotive force (e.m.f.) in the loop which acts as the secondary of a transformer, the electromagnet being the primary. Pulsations in the blood vessel diameter vary the loop area and with it the induced e.m.f. thus providing a linear measure of relative changes in vascular diameter. Changes in the order of 2 micra in a venous diameter of 5 mm can be resolved in-situ. Examples are given of registration of phasic venous diameter changes at the frequencies of the heart beat, respiration and Mayer waves. Pharmacological tests illustrate the ability to detect venous vasomotion in response to a dose below 0.1 microgram/kg of nitroglycerin in dogs.

Animals↗
PubMed1978

Electromagnetic rheoangiometry: an extension of selective angiography.

A harmless magnetic field produced by an extracorporeal magnet induces in the blood vessels of a living subject electrical signals which carry information about regional blood flows. Loop probes of hairlike consistency equipped with fine electrodes can now be introduced percutaneously and selectively into the vasculature through angiographic catheters to pick up these magnetically induced signals at selected loci. In addition to a continuous record of phasic blood flow, the loop sensors provide signals which measure variations in vascular diameters, thus yielding a continuous record of active and passive vasomotion. Coupled with blood pressure recordings, these data will permit determination of the elastic constants of blood vessels in situ. The manifold capabilities of electromagnetic rheoangiometry for providing continuous records of these vascular parameters are illustrated in dogs with tracings using multichannel recorders which provide continuous information of arterial blood pressures, instantaneous and mean blood flows, and instantaneous and mean vascular diameter changes simultaneously in two nonadjacent arteries.

Animals↗
PubMed1978

Differential effects of Pitressin on blood flow and oxygen extraction in canine vascular beds.

Physiologic studies in dogs have been performed with an intravascular flow/diameter sensor which can be introduced directly into the aorta or its branch vessels through a percutaneous radiologic catheter. These studies have focused upon attempts to devise a clinically practical means to protect the small intestine from radiation damage during therapy of abdominal and pelvic malignant tumors. The effects on superior mesenteric, renal, and lower extremity blood flows of controlled infusions of Pitressin given directly into the superior mesenteric artery or into a peripheral vein have been measured. In addition, using these regional flow measurements and arteriovenous differences in oxygen content, regional tissue oxygen extraction rates during Pitressin infusions have also been estimated. The data show that intravenous Pitressin at an infusion rate of 0.0124 U/kg/min may be almost as effective as Pitressin given directly into the superior mesenteric artery in lowering superior mesenteric blood flow (40%-70% reduction for intravenous, 50%-70% for direct arterial infusions) and intestinal oxygen extraction (20%-40% reduction for intravenous, 40%-50% for direct arterial infusions). The effects of Pitressin at similar dose rates on the kidney and the lower extremity are less reproducible, and it is possible that relatively selective radiation protection of the intestine using systemic (intravenous) infusions of Pitressin during abdominopelvic radiotherapy might be achievable.

Animals↗
PubMed1978

Gamma-glutamyltransferase in putative premalignant liver cell populations during hepatocarcinogenesis.

The activity of gamma-glutamyltransferase, as measured quantitatively and by histochemical staining, was studied in different cell populations during the induction of liver cancer with 2-acetylaminofluorene (2-AAF) or diethylnitrosamine and compared with findings in fetal and in intact and regenerating adult liver. The enzyme activity is 20-fold higher in 12-week nodules than in control livers and 30-fold higher in 20-week nodules than in controls. A similar 30-fold increase in activity relative to control is present in hepatomas, induced by either 2-AAF or diethylnitrosamine, and in fetal hepatocytes. The enzyme shows increases in activity in foci of very early putative preneoplastic hepatocytes induced by a single dose of diethylnitrosamine and selected by low doses of 2-AAF plus partial hepatectomy. By 7 days, the foci show a 4-fold increase in enzyme activity, and by 3 weeks they are 40-fold higher than in the control liver. Histochemically, the foci are strongly positive for gamma-glutamyltransferase, especially in the bile canaliculi. By 21 days, the ductular (oval) cells induced by 2-AAF have disappeared. When stained for the enzyme activity, the foci stand out clearly against the negative background of the liver, allowing easy quantitation. It appears that gamma-glutamyltransferase is a useful marker for preneoplastic hepatocytes.

2-Acetylaminofluorene↗
PubMed1977

A system for intravascular, radially orientation-independent electromagnetic flow- and diameter-sensing.

The difficulty of optimally orienting an intravascular loop probe of an extracorporeal field electromagnetic flow meter is circumvented by uniting 2 mutually perpendicular loop sensors into a single flow-diameter probe. When one of the loops is unfavorably oriented in the magnetic field, the orientations of the other loop is more favorable. The most unfavorable case is a 45 degrees angle between the magnetic field and the planes of the loops, when the signal drops to 70.7% of the optimal value. By taking the square root of the sum of the squares of the 2 loop transducer signals, one obtains an output for flow and diameter measurements which is independent of the probe orientation. This operation can be accomplished electronically.

Animals↗
PubMed1977

Induction angiometer. Electromagnetic magnification of microscopic vascular diameter variations in vivo.

It is possible to obtain continuous linear recordings of changes in vascular diameters on the basis of the electromagnetic induction principle. An extracorporeal coil energized by an alternating current generates an AC magnetic field and acts as a transformer primary. An intravascular loop of fine wire acts as transformer secondary. The EMF induced in the loop is proportional to the diameter of the vessel which confines the loop. Relative measurements do not require a calibration. Absolute measurements require radiographic determination of vessel diameter. Changes of less than 0.1% in vascular diameters can be easily recorded. Variations in pulsatile diameter changes as well as pharmacologically induced changes in mean diameter have been studied.

Blood Vessels↗
PubMed1976

Extracorporeal magnet perivascular electromagnetic flow meters.

The "interrupted resonance" circuit proved effective in combination with an extracorporeal magnet in permitting electromagnetic blood flow measurements to be made in branch arteries of dogs by application of perivascular cuffs equipped with pick-up electrodes contacting the vessel wall. A four-turn coil, acting as a transformer secondary measures the amplitude of the magnetic field component which is effective in inducing the flow signal and thus permits calibrations for arbitrary orientations of the perivascular cuff relative to the magnetic field of the extracorporeal magnet. Recordings of mean and phasic blood flow in dogs' arteries provide illustrations of effectiveness in pharmacological studies and exhibit the reliability of the non-occlusive zero-flow base line obtained by de-energizing the magnet.

Animals↗