Publications by authors named "Horak D"

In order to eliminate the kinetic limitation of chymotryptic hydrolysis of proteins due to diffusion, nonporous hydroxyalkyl methacrylate solid support was developed and used for oriented immobilization of chymotrypsin by means of suitable polyclonal antibodies. Nonporous microspheres were prepared by dispersion copolymerization of 2-hydroxyethyl methacrylate and ethylene dimethacrylate in an alcohol-toluene mixture stabilized with cellulose acetate butyrate. The resulting particles were 1.

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Spherical poly(2-hydroxyethyl methacrylate) particles 0.4-0.6 mm in diameter prepared by suspension polymerization were used for embolization of the internal thoracic artery in ten dogs and the renal artery in two dogs.

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Nonporous cross-linked poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) (poly(HEMA-co-EDMA)) microspheres were prepared by dispersion polymerization of HEMA and EDMA. The polymerization was performed in toluene/2-methylpropan-1-ol in the presence of cellulose acetate butyrate as a steric stabilizer and dibenzoyl peroxide initiator. The particle size may be increased by decreasing the toluene/2-methylpropan-1-ol ratio and by increasing polymerization temperature.

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Purpose: To describe hospital survival for cancer patients who require mechanical ventilation.

Materials And Methods: A prospective, multicenter observational study was performed at five academic tertiary care hospitals. Demographic and clinical variables were obtained on consecutive cancer patients at initiation of mechanical ventilation, and information on vital status at hospital discharge was acquired.

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Silver iodide complexes have been used as an effective radiopacifying agent to prepare radiopaque poly(2-hydroxyethyl methacrylate) (poly(HEMA)) particles. Incorporation of silver iodide complexes inside the poly(HEMA) particles was achieved by first swelling particles in potassium iodide solution and precipitating the silver iodide complexes using a 30 wt% solution of silver nitrate. The dry particles contained 15 wt% of silver iodide complexes.

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Purpose: To develop prospectively and validate a model for probability of hospital survival at admission to the intensive care unit (ICU) of patients with malignancy.

Patients And Methods: This was an inception cohort study in the setting of four ICUs of academic medical centers in the United States. Defined continuous and categorical variables were collected on consecutive patients with cancer admitted to the ICU.

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Cytotoxicity of poly(2-hydroxyethyl methacrylate) [poly(HEMA)] hydrogel spherical particles, prepared by radical suspension polymerization and designed for endovascular occlusion, was studied in vitro on cell cultures. Testing methods included a direct contact test and extraction test. No inhibition of growth of cells surrounding the poly(HEMA) beads and a very low inhibition of cell viability, only in concentrated extracts in long-term contact, were observed.

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New iodine-containing polymeric hydrogel particles were prepared by suspension radical copolymerization of 2-hydroxyethyl methacrylate (HEMA), 3-(methacryloylamidoacetamido)-2,4,6-triiodobenzoic acid (MABA) and ethylene dimethacrylate (EDMA) in an aqueous medium using azobisisobutyronitrile as an initiator and magnesium hydroxide as a suspension stabilizer. To impart porosity to the product, cyclohexanol and 1-dodecanol were added as inert diluents to the polymerization mixture. Particles containing 27 wt % iodine produced radiopacity sufficient to observe a clearly visible X-ray image.

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Poly (2-hydroxyethyl methacrylate) (PHEMA) particles of cylindrical and spherical shape were developed as a preparation for tumor treatment or control of hemorrhage by blocking their blood supply. In this report, PHEMA particles were used for the management of hemobilia, that is, bleeding into biliary passages. The origin of hemobilia in 31 patients was localized by selective angiography.

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The use of ganciclovir at the time of cytomegalovirus (CMV) infection but before disease onset has been termed "preemptive" therapy. This preemptive ganciclovir administration has been shown to be an effective method for preventing severe CMV disease after allogeneic bone marrow transplantation (BMT), but the optimal method of CMV surveillance is not clear. The purpose of this study was to evaluate effectiveness, side effects, and long-term outcome of preemptive ganciclovir therapy in allogeneic BMT recipients when ganciclovir is prescribed solely on the basis of CMV detection in day +35 bronchoalveolar lavage (BAL).

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The application of superselective endovascular occlusion in vascular radiology has broadened the scope of possible radical surgery of giant angiodysplasias by reducing considerably the risk of severe haemorrhage during the surgery. Occlusion was performed on 229 patients using spherical and cylindrical particles of porous poly(2-hydroxyethyl methacrylate). The treatment of a patient suffering from angiodysplasia of the pelvis is described as an example.

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Study Objective: To determine the value of pulmonary function tests (PFTs) in predicting the development of human cytomegalovirus (CMV)-associated interstitial pneumonia (IP) in allogeneic bone marrow transplant (BMT) recipients.

Design: Nonrandomized, prospective, open-trial study.

Setting: Tertiary referral medical center.

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The objective of this study was to clarify conflicting reports of the sensitivity and specificity of bronchoalveolar lavage or bronchial washings for diagnosing invasive pulmonary aspergillosis. The study was a retrospective review of 300 consecutive patients in a tertiary referral centre subjected to 343 fiberoptic bronchoscopic procedures for the evaluation of pulmonary infiltrates. Classification of paired fungal culture and cytologic examination of bronchoalveolar lavage or bronchial washing fluid according to clinical, radiographic, histological and autopsy evidence of invasive pulmonary aspergillosis.

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A haemostatic material suitable for embolization was prepared by the adsorption of haemostatics--ethamsylate and aminocaproic acid in the spherical particles of porous poly(2-hydroxyethyl methacrylate) (p(HEMA)). The degree of purification of ethamsylate-treated particles was tested by an analysis of donor blood in contact with the material. An evaluation of the haemostatic properties of these materials was obtained by the determination of the indicators of blood clotting: activated partial thromboplastin time, thrombin time, and prothrombin time.

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The aminohexyl derivative of the copolymer of 2-hydroxyethyl methacrylate and ethylene dimethacrylate (p(HEMA)-Hex) in the form of regular spherical particles was used as a polymeric carrier for chemically sorbed methotrexate (MTX). The effect of the washed p(HEMA)-Hex-MTX carrier on the morphological structure of donor blood, on blood coagulation indicators and on responses of the living tissue surrounding the material which has been in the blood vessel of the rabbit for various periods of time was evaluated. MTX is capable of diffusion for several days from the embolic material.

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Embolization using poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel particles, of cylindrical spherical form, was successfully achieved in 42 children treated for non-operable haemangiomas of the liver, and angiodysplasias. Spherical PHEMA hydrogels appeared to be the only possibility for the treatment of 26 children suffering from extensive cavernous haemangiomas of face and neck. Particles were able to cover the tumour, stop its growth and allow the use of local hyperthermia with the electromagnetic field.

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Background: Cytomegalovirus (CMV)-associated interstitial pneumonia is a major cause of death after allogeneic bone marrow transplantation. We conducted a controlled trial of ganciclovir in recipients of bone marrow transplants who had asymptomatic pulmonary CMV infection. We also sought to identify risk factors for the development of CMV interstitial pneumonia.

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A retrospective review of patients treated for Hodgkin's disease or other malignant lymphomas between 1953 and 1988 revealed 10 cases of spontaneous pneumothorax. Nine had Hodgkin's disease whereas one had diffuse histiocytic lymphoma. Ages of the 10 patients ranged from 11 to 54 years, although nine were less than 30-years old.

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Spherical particles of porous poly(2-hydroxyethyl methacrylate) have been used in the treatment of patients suffering from focal alterations of the liver, namely haemangioma and hypervascular tumour. The treatment consisted of the preoperative endovascular occlusion of branches of the hepatic artery using these spherical particles, and was followed by an operation. The main merit of the preoperative occlusion of blood vessels is that it substantially reduces blood loss during surgery.

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This study examines the value of bronchoalveolar lavage (BAL) in diagnosing lymphangitic carcinomatosis. A retrospective analysis of fiberoptic bronchoscopic records at a tertiary referral hospital was performed. Twelve patients with neoplastic disease and diffuse pulmonary infiltrates compatible with lymphangitic carcinomatosis who underwent diagnostic fiberoptic bronchoscopy were identified.

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In this study we report the results of toxicological, histological and haematological experiments on radiopaque spherical particles based on poly(2-hydroxyethyl methacrylate). These particles have been developed for endovascular occlusion of various organs. Radiopacity was attained by two independent methods: the chemical attachment of radiopaque substances to the hydrogel or the precipitation of radiopaque substances in the hydrogel network.

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