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Biomedical subjects

R M Nalbandian

Publications and source records attributed to R M Nalbandian.

At least 19 recordsLinked to original sources

A molecular-based magnet test for malaria.

The molecular-based magnet test for malaria is shown to be more sensitive than the thin blood film test. The globally used thin blood film test is less sensitive because it uses preparation steps that result in the reduction of the absolute number of diagnostically pertinent erythrocytes. Several reports of diagnostic error with the thin film test and the thick film test have appeared in the literature. In marked contrast to the commonly accepted tests, the magnet test concurrently partitions and concentrates the infected erythrocytes present in the initial sample. The magnetic test permits a brief and sensitive microscopic-based enumeration of the malaria-infected erythrocytes in the enriched sample. Diagnostically pertinent hemozoin is simply identified through two of its specific molecular properties: paramagnetism and birefringence. The former property mediates the capture and enrichment of malaria-infected erythrocytes within the magnetic flux and the latter property manifests the characteristic birefringence demonstrated by polarized light.

Animals↗

The diagnostic histopathologic features of ocular malaria.

BACKGROUND: The ocular complications in patients with malaria have been studied clinically by many investigators, but the histopathologic changes were rarely described and generally regarded as nonspecific. METHODS: The eye of a 53-year-old man who died of chloroquine-resistant Plasmodium falciparum malaria was studied by brightfield and polarized light microscopy. FINDINGS: An epibulbar hemorrhage that involved the conjunctiva, episclera, and tendinous insertion of the medial rectus muscle was present. Cytoadherence and rosetting of the parasitized erythrocytes were observed within the partially occluded lumens of small retinal and uveal blood vessels. The birefringence of hemozoin (malarial pigment) within the lumens of small ocular blood vessels and in the hemorrhagic epibulbar area was demonstrated by polarized light. CONCLUSION: Birefringent hemozoinemia in vascular lumens of ocular tissues indicates systemic malarial infestation by any of the four species of malaria. Cytoadherence and rosetting of the parasitized erythrocytes inside ocular capillaries and venules is diagnostic of P. falciparum and is an important cause of ocular hemorrhage.

Animals↗

[Properties of a nitrite reductase inhibitor protein from Pseudomonas aeruginosa].

The amino acid composition and major physico-chemical properties of the "nonblue" copper protein isolated earlier from Pseudomonas aeruginosa have been determined. It has been found that the azurin oxidase, cytochrome c551 oxidase and superoxide dismutase activities of the enzyme are inhibited by this protein. The inhibition seems to be due to the protein interaction with the electron-accepting center of nitrite reductase.

Amino Acids↗

Enchondromatosis and hemangioma (Maffucci's syndrome) with orbital involvement.

Maffucci's syndrome is a rare, congenital disease of unknown cause characterized by the development of multiple enchondromas and soft-tissue hemangiomas. We treated a 34-year-old man with Maffucci's syndrome, bilateral proptosis secondary to multiple intraorbital hemangiomas, corneal exposure secondary to a left facial nerve palsy, and multiple intra-abdominal tumors. The skeletal manifestations were not clinically apparent and were only discovered after a careful radiologic survey. Simultaneous bilateral orbital cavernous hemangiomas should alert the physician to the possibility of Maffucci's syndrome.

Adult↗

[Purification of flavin-containing liver polyamine oxidase and luminescent properties of the ferment].

A flavin-containing polyamine oxidase was isolated in an electrophoretically homogeneous state from cattle liver cytosol. The molecular mass, subunit composition and flavin content of the enzyme were determined; flavin, was shown to be covalently bound to the protein fragment of the polyamine oxidase molecule. Some optical and luminescent properties of the native and denatured enzyme were investigated. Denaturation and quenching were found to affect the luminescent properties of polyamine oxidase.

Animals↗

[Monoclonal antibodies to ceruloplasmin and their use for immunoenzyme assay of this protein].

The hybridoma technology was used to produce monoclonal antibodies to human ceruloplasmin. The antibodies were found to be related to Ig G1. Using these monoclonal antibodies for PAP-ELISA of ceruloplasmin, it was possible to determine 10(-11) M of the protein. Monoclonal antibodies coupled to CNBr-Sepharose were used for the rapid one-stage purification of ceruloplasmin from human placental serum. Ceruloplasmin obtained by this method contained no type 2 copper normally detected in protein preparations by conventional methods.

Animals↗

[Relation between the membrane and soluble forms of dopamine beta-monooxygenase].

The quantitative ratio of membrane-bound and soluble forms of dopamine beta-monooxygenase from chromaffin granules obtained under different experimental conditions was determined. The amount of the membrane-bound form of dopamine beta-monooxygenase made up to no less than 60% of the total enzyme pool, when the granules were obtained and lyzed in the presence of pepstatin, phenylmethylsulfonyl fluoride, N-ethylmaleimide and catalase. In the absence of protectors practically all the enzyme can be obtained in the soluble form without detergent treatment. The effects of some ionic and nonionic detergents on the enzymatic activity of both forms of dopamine beta-monooxygenase were studied. No inhibition of dopamine beta-monooxygenase by 2% octyl glucoside or 1% Triton X-100 was observed. A comparative analysis of specific activities, subunit compositions, antigenic and physico-chemical properties of membrane-bound and soluble forms of dopamine beta-monooxygenase was carried out.

Adrenal Glands↗

Epithelial downgrowth following wound dehiscence after extracapsular cataract extraction and posterior chamber lens implantation: surgical management.

Epithelial downgrowth occurred along a fistulous (nonfiltering) tract containing an incarcerated anterior capsular flap after extracapsular cataract extraction and posterior chamber lens implantation complicated by wound dehiscence. Months later, a YAG posterior capsulotomy was performed before it was realized that posterior capsule opacification was associated with epithelial downgrowth involving the posterior capsule. Surgical management of epithelial downgrowth after extracapsular cataract extraction and posterior chamber lens implantation is discussed, with emphasis on the role of combined cryotherapy, dissection of the retrocorneal membrane, and complete removal of the capsular bag. Histopathologically, we found it difficult to differentiate lens epithelial cells from corneal epithelial downgrowth within the capsular bag, but monoclonal antibody for keratin may help identify corneal epithelial cells.

Anterior Chamber↗

[Peptidylglycine alpha-amidating monooxygenase from bovine heart atrium secretory granules and adrenal chromaffin granules].

About 40-60% of the peptidylglycine alpha-amidating amonooxygenase activity in the lysates of secretory granules from bovine atria and adrenal medulla isolated and lyzed in the presence of pepstatin, phenylmethylsulfonyl gluoride, N-ethylmaleimide and catalase, was found to be in the soluble form. The remaining part bound to the membrane fraction was extracted with Triton X-100. The procedure of purification of the soluble form of peptidylglycine alpha-amidating monooxygenase from both atrial and chromaffin granules in electrophoretically homogeneous enzyme preparations was developed. The enzyme is made up of a single subunit with a molecular mass of 68 kDa and contains one copper atom per molecule. The EPR spectra of peptidylglycine alpha-amidating amonooxygenase and dopamine beta-monooxygenase were found to be practically identical, thus indicating that the copper environment in the both enzymes is the same. Both peptidylglycine alpha-amidating monooxygenase and dopamine beta-monooxygenase are inhibited by the neurocuprein apoform, an extremely acidic protein isolated from brain and secretory granules of different endocrine tissues.

Adrenal Medulla↗

A biologic tissue adhesive for vitreoretinal surgery.

Commercially available tissue glue was injected subretinally under mechanically induced retinal detachments in rabbit eyes resulting in chorioretinal adhesions at the injection site. After serial enucleation all eyes underwent histologic evaluation. Results were encouraging, but pooled fibrinogen is not acceptable for human use. A substitute for the pooled fibrinogen fraction, an adhesive using autologous plasma was prepared and studied after subretinal and intravitreal injection into rabbit and pig eyes. Postoperative clinical follow-up was one year for the rabbit eyes and one month for the pig eyes, after which all globes were enucleated. Histopathologic evaluation demonstrated circumscribed chorioretinal adhesions at the injection site. The autologous bioadhesive was applied as an adjunct in vitreoretinal surgery over macular holes and large retinal tears. As it is relatively short acting (ie, 4-6 days), it may be considered as a possible addition to existing techniques, facilitating difficult surgical procedures.

Adult↗

[Effect of hydrazine on properties of cytochrome oxidase].

The effects of hydrazine on ferrocytochrome c oxidation by cytochrome oxidase and on spectral properties of the enzyme were studied. Hydrazine was found to modify the spectral properties of lipid-depleted preparations of cytochrome oxidase dissolved in 1% cholate and to inhibit the cytochrome c oxidase activity of the enzyme, whereas the kinetic properties of lipid-enriched and Tween preparations were unchanged by hydrazine. Cytochrome oxidase was found to possess a hydrazine oxidase activity. This activity was not coupled with the specific cytochrome c oxidase activity. The effect of pH on the observed changes was studied. Hydrazine was found to yield protein bands in the optical spectra of cytochrome oxidase as 580 nm, 537 nm and 845 nm. It is concluded that hydrazine interacts with the oxygen-binding site of cytochrome oxidase. The effect of hydrazine on the formation of the "ferryl" form (Fe4+a3/Cu2+b) of the enzyme is discussed.

Animals↗

Pluronic F-127 gel preparation as an artificial skin in the treatment of third-degree burns in pigs.

A blinded study was designed to provide qualitative and quantitative evaluation on the possible therapeutic benefits of the use of Pluronic Polyol F-127 as a substitute skin in standardized third-degree thermal burns. Three separate burns, approximately 1600 mm2, were induced on the shaved backs of young, anesthetized pigs. Each animal served as its own control. One burn site was left untreated while the other two sites were covered with coded preparations of the Pluronic F-127 gel with additives. Polaroid photographs with a fixed focal-length camera were taken of all burn sites for planimetry analysis. Biopsies taken confirmed that third-degree burns were achieved. The pigs were followed for 30 days. The rate of healing of third-degree thermal burns was significantly accelerated over control sites when treated with Pluronic Polyol F-127 plus propylene glycol. When the bacteriostatic agent Garamycin was also added, the rate of healing remained significantly better than untreated controls. With the addition of Piracetam, burn wound healing was actually retarded within 30 days, when applied topically. Thus, wound healing was both accelerated and retarded as a function of the particular Pluronic preparation used to treat specific burn sites. This experimental modulation of wound healing suggests that the non-ionic poloxamer, Pluronic F-127, can significantly enhance the rate of wound healing by some unknown mechanism, possibly by stimulation of epithelial growth factor (EGF).

Animals↗

[Oxidation by nitrite of azurin and cytochrome c-551 from Pseudomonas aeruginosa].

The nitrite oxidizes reduced azurin and cytochrome c-551 from Pseudomonas aeruginosa. The effects of pH, ionic strength and concentrations of nitrite, EDTA and the protein on the oxidation were investigated. The results obtained indicate that nitrite interacts not only with the terminal electron carrier of the nitrite reducing chain (nitrite reductase, cytochrome cd1) but also with the intermediate electron carrier components of the chain (azurin and cytochrome c-551).

Azurin↗

[Purification and properties of copper thionein].

A novel procedure for purification of copper-thionein from rabbit liver was developed. The molecular mass, copper, and thiol contents were determined. The properties of the protein were compared with those of Cd-thionein. Copper was removed from Cu-thionein and the reconstitution was achieved. The binding of copper leads to an increase in absorbance at 260 nm.

Animals↗

[Luminescent properties of NADPH: adrenodoxin reductase].

The fluorescent and phosphorescent properties of NADPH-adrenodoxin reductase were investigated. It was shown that the fluorescence of protein tryptophanyls was quenched completely by acrylamide and partially by ionic quenchers (I- and Cs+). A removal of the prosthetic group from the protein causes insignificant changes in fluorescent properties of the enzyme. The denaturation of the enzyme by urea was accompanied by growth of quenching parameters. Indeed, some differences were observed in the quenching of flavin fluorescence by ionic quenchers (I- and Cs+). NADPH appeared to be an efficient quencher of NADPH-adrenodoxin reductase tryptophan fluorescence. Using Förster's equations for non-radiative energy transfer, the distance between NADPH-binding site and tryptophanyls was evaluated to 35-40 A.

Acrylamide↗

Silicone implants in dogs. A ten-year histopathologic study.

The biocompatibility of implanted materials is important to the successful long-term results obtained in reconstructive surgery with these materials. Recently, interest has emerged regarding host response to the wear debris of implanted material. Since 1962 flexible implant materials have been studied in the Orthopaedic Research Department at Blodgett Memorial Medical Center. An important aspect of this study has been a concern for host tolerance and the evaluation of biologic responses to implanted silicone elastomer. Three dogs in which implants of silicone elastomer had been in place for more than ten years were carefully studied by complete autopsy. A benign foreign-body giant cell response to local silicone wear debris was observed. No silicone particles or macrophage giant cell reactions were found in any distant organs. The host response to silicone wear debris was benign, and no adverse systemic influences were noted.

Amputation Stumps↗