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F Ungar

Publications and source records attributed to F Ungar.

At least 19 recordsLinked to original sources
PubMed1997

Analysis of hydroxy and keto cholesterols in oxidized brain synaptosomes.

A rapid method for the simultaneous determination of cholesterol and its oxidation products as well as alpha-to-copherol and tocopherolquinone in brain subcellular fractions is described. The samples are saponified and extracted with hexane. It is not necessary to remove cholesterol in the sample before analyzing for oxysterols. The hexane extract can be used for the assay of cholesterol compounds by capillary gas chromatography and tocopherol compounds by liquid chromatography using a procedure reported previously. Oxidation of synaptosomes by a mixture of Fe2+ plus ascorbate resulted in the production of 7-keto-, 7 alpha-hydroxy-, 7 beta-hydroxy-, and 5 alpha, 6 alpha-epoxycholesterols. The identities of these products were confirmed with gas chromatography/mass spectrometry. Cholesterol oxidase treatment did not result in the formation of any of the above compounds. Thus the types and amounts of the products of oxidation of cholesterol were dependent upon the oxidizing agent. Extraction of the oxysterols under milder conditions without saponification using sodium dodecyl sulfate cannot be used since such treatment results in low recovery of oxysterols. Oxidation of synaptosomes by low concentrations of ferrous iron and ascorbate resulted in (i) low levels of oxidation of cholesterol which could be followed by estimating the production of oxysterols and (ii) oxidation of a substantial percentage of alpha-tocopherol. The proposed procedure will be useful in monitoring the oxidation of small quantities of membrane cholesterol in vitro.

Animals↗
PubMed1997

Oxidation of cholesterol in synaptosomes and mitochondria isolated from rat brains.

Cholesterol and alpha-tocopherol oxidations were studied in brain subcellular fractions isolated from cerebral hemispheres of 4-month-old, male Fischer 344 rats. The fractions were suspended in buffered media (pH 7.4, 37 degrees C0 and oxidized by adding (i) ferrous iron (Fe2+) with or without ascorbate or (ii) peroxynitrite (an endogenous oxidant produced by the reaction of superoxide and nitric oxide). Treatment of subcellular fractions with Fe2+ in the presence or absence of ascorbate produced primarily 7-keto- and 7-hydroxy-cholesterols and small amounts of 5 alpha, 6 alpha-epoxycholesterol. Since brain contains high levels of ascorbate, and release of iron could result in oxysterol formation. Peroxynitrite oxidized alpha-tocopherol but not cholesterol. Hence, the toxicity of peroxynitrite or nitric oxide could not be due to cytotoxic oxysterols. When synaptosomes were incubated for 5 min in the presence of 0.5 to 2 microM Fe2+ and ascorbate, alpha-tocopherol was oxidized while cholesterol remained unchanged. Thus, alpha-tocopherol is functioning as an antioxidant, protecting cholesterol. Diethylenetriaminepentaacetic acid blocked production of oxysterols, whereas citrate, ADP and EDTA did not. A significant percentage of mitochondrial cholesterol was oxidized by treatment with Fe2+ and ascorbate. Hence, mitochondrial membrane properties dependent on cholesterol could be particularly susceptible to oxidation. The oxysterols formed were retained within the membranes of synaptosomes and mitochondria. The 7-oxysterols produced are known to be inhibitors of membrane enzymes and also can modify membrane permeability. Hence, oxysterols may plan an important role in brain tissue damage during oxidative stress.

Animals↗
PubMed1993

Features of the polarity of the Golgi apparatus of frog photoreceptors: studies with lectins and with Brefeldin A.

The cis-trans polarity of the Golgi apparatus is important in Golgi functioning in glycosylation, sorting and other processes. The present work extends our prior studies on the polarity of the Golgi apparatus of frog (Rana) rod photoreceptors. We demonstrate that Golgi structures with the morphology and distribution of cis elements show the heaviest deposition of osmium. Elements with morphology and cytochemical reactivities resembling trans Golgi structures remain discernible as discrete arrays after exposure of the cells to Brefeldin A. These properties strengthen our identification of cis and trans elements since they are shared with corresponding Golgi structures in other cell types. We have also investigated the binding of lectins to sections prepared by cryoultramicrotomy. We find that Concanavalin A, with probable chief affinity for core mannoses in oligosaccharides, localizes to cis, medial and trans elements of the photoreceptor's Golgi apparatus. Wheat germ agglutinin, with likely affinity at least partly for terminal N-acetylglucosamines, localizes to trans and medial elements. A trans localization is seen with Ricinus communis agglutinin (RCA 120), but this lectin binds extensively only after neuraminidase treatments suggesting that its chief affinity is for galactose residues that are penultimate to sialic acids (neuraminic acids) in the native oligosaccharides. Overall, the pattern of lectin binding to Golgi structures that we observe resembles that seen in a variety of other cell types. The distribution of glycosylated molecules we detect in the photoreceptor's Golgi apparatus may bear upon such matters as the unusual features of the glycosylation of mature opsin.

Animals↗
PubMed1989

Infradian modulation of liver nucleic acid and lipid content of adult female Lewis/S rats.

Infradian modulation with periods of 168 h and 120 h characterizes the RNA, DNA and lipid content of the liver in adult female Lewis/S rats. Multilinear analysis shows that the fit of an infradian cosine curve with these periods is statistically significant below the 5% level (P = 0.011; P = 0.007 and P = 0.013) and that they account for 19.0, 22.7 and 20.1% of the overall variability, respectively.

Activity Cycles↗
PubMed1988

Circadian stage-dependent effect of ACTH and melatonin on protein synthesis by rat adrenal cells.

The objective of the present study was to determine the circadian effects of melatonin and two different ACTH preparations: a synthetic heptadecapeptide with adrenocorticotrophic action (Synchrodyn 1-17, HOE 433) and a natural ACTH (Acthar, Armour). Both ACTH preparations acted in a circadian stage-dependent fashion affecting the MESOR and the amplitude of total protein synthesis of rat adrenal cells. The results also indicated interaction of melatonin with the rhythmic action of ACTH. We conclude that circadian adrenocortical organization also modulates protein synthesis.

Adrenal Glands↗
PubMed1987

Lead-dependent deposits in diverse synaptic vesicles: suggestive evidence for the presence of anionic binding sites.

We have observed electron dense deposits dependent on incubation of aldehyde-fixed tissues with lead ions within synaptic vesicles of several types of neurons that differ in the neurotransmitters utilized and in the secretory granules of the adrenal medulla. Evidently, vesicle components that can interact with lead ions are widespread. A plausible explanation for the occurrence of the deposits is the presence of anionic binding sites within the vesicles. This would agree well with other biochemical, cytochemical, and immunocytochemical evidence, such as that indicating the presence of sulfated macromolecules in certain synaptic vesicles. Anionic binding sites could play significant roles by participating in processes such as Ca2+ storage, stabilization of pH gradients, or the control of osmotic phenomena.

Adrenal Medulla↗
PubMed1987

Rhythmic pineal-hypophyseal-adrenal intermodulations ex vivo.

To assess circadian and circaseptan rhythmic intermodulation, female mice, kept on regimens of 12 hr light (L) alternating with 12 hr of darkness (D) (LD 12:12) were sampled for 1-13 days at six circadian stages. Pineals were removed and homogenized with 0.9% NaCl. Adenohypophyses were bisected and incubated in Krebs-Ringer buffer (KRb) and/or with 10(-7) M melatonin (Mt). Adrenals were bisected and incubated with KRb, with 10(-7) M Mt, with 0.05 IU of ACTH 1-17 (Sy; Hoechst, Italy), or with Sy + 0.025 ml of the aqueous pineal homogenate (APH). ACTH and prolactin (PRL) in adenohypophysis incubation fluid were determined by radioimmunoassay (RIA), and corticosterone in adrenal incubation fluid was determined by RIA or by a fluorometric method. By this chronobiologic approach, time series were collected systematically in the search for predictable variability. Once these series reveal an algorithmically formulatable pattern, with a waveform validated by inferential statistical means, they are graded in terms of complexity as alpha, beta, gamma, and delta rhythms. Spontaneously (alpha-) rhythmic along the 24-h scale is the corticosterone produced by bisected adrenal glands incubated with KRb only, and the Mt content of the APH, in keeping with earlier work. Reactively (beta-) rhythmic is the response, again along the 24-hr scale, of the adrenal to Sy or Mt and the response of the anterior pituitary to Mt at different circadian times. Modulatory (gamma and delta) rhythms characterize the Mt effect on the (beta-rhythmic) adrenal stimulation by Sy. Chronomodulations thus emerge as more or less complete sequences of a decrease, no effect and/or increase; or, rather, as an attenuation, no effect and/or amplification by the pineal, of the pituitary effect upon the adrenal. Linear least-squares rhythmometry, mostly single cosinors, describes and quantifies circadian (alpha, beta, and gamma) and infradian (delta) rhythms in the original series and in the differences in responses [beta - alpha] and [gamma - beta] (P less than 0.001 in each case). These spontaneous alpha, response beta, modulatory gamma, and frequency-divided delta rhythms reveal a collateral neuroendocrine hierarchy, characterized by the pineal feedsideward phenomenon, as a feature of interactions recurring with circadian and infradian frequencies.

Adrenocorticotropic Hormone↗
PubMed1986

Corticotropin specifically stimulates the uptake and intracellular movements of sterol carrier protein in adrenals.

Sterol carrier protein (SCP), also known as liver fatty acid binding protein, is a major adrenal protein localized in the cytosol and inner mitochondrial membrane. SCP is synthesized in liver and intestine and then rapidly secreted into blood, where it associates primarily with the high density lipoprotein fraction. Studies using steroidogenesis inhibitors showed that corticotropin has a specific effect on the uptake of SCP and its movement with cholesterol to the inner mitochondrial membrane. Thus, SCP appears to be intimately involved in the mechanism(s) of adrenal steroidogenesis from cholesterol.

Adrenal Cortex↗
PubMed1985

Osteosynthesis of subtrochanteric fractures. A review of different methods.

The authors analysed the long-term results of 72 subtrochanteric fractures treated surgically over a period of 13 years. The case material was subdivided according to type of fracture and method of osteosynthesis and the results were evaluated with a view to ascertaining the best method of treatment in each type of fracture. The best results were obtained with osteosynthesis using an angled nail plate.

Adolescent↗
PubMed1985

Plasma and synovial fluid concentrations of isoxicam in meniscectomized patients.

Concentrations of isoxicam in the plasma and synovial fluid of 7 patients were investigated by means of high-pressure liquid chromatography. The samples were collected after 7 days' treatment with a single 200 mg isoxicam capsule taken each morning. A highly significant correlation was found (r = 0.82; p less than 0.05) between isoxicam concentrations in the plasma and in the synovial fluid. The mean concentration (+/- s.d.) was 25.54 +/- 10.91 micrograms/ml in the plasma and 17.47 +/- 6.54 micrograms/ml in the synovial fluid; the ratio between isoxicam concentrations in the synovial fluid and in the plasma was 71.06% +/- 18.83.

Adult↗
PubMed1985

Rotatory subluxation of the atlanto-axial joint.

Twelve cases of rotatory subluxation of the atlanto-axial joint are presented. The pathogenesis of this lesion is discussed, in particular why it is prevalent in children. The radiographic and clinical features are described. The long-term results emphasize the importance of early diagnosis and treatment, which are essential if the best results are to be obtained.

Adult↗
PubMed1984

Intramitochondrial movement of adrenal sterol carrier protein with cholesterol in response to corticotropin.

Sterol carrier protein (SCP) is a highly abundant, ubiquitous, low molecular weight protein that has a rapid turnover and multifunctional roles in lipid metabolism and transport. It is also known as the fatty acid-binding protein. These and other characteristics led to studies on the possible role of SCP in mediation of steroidogenic responses of the adrenal gland to corticotropin. To quantitate the level of SCP in adrenal tissue and subcellular fractions, a specific immunochemical assay was developed using an antibody to homogeneous liver SCP. SCP is a major protein in adrenal cells (greater than 100 micrograms/mg of total protein). The bulk of it is present in the soluble (60%) and mitochondrial (35%) fractions. Nearly all mitochondrial SCP is present in the inner membrane. Adrenal SCP undergoes a dramatic diurnal variation, varying from 2% to 12% of total protein. When corticotropin was administered in vivo in the presence of aminoglutethimide, an inhibitor of steroidogenesis, there was a parallel movement of SCP with cholesterol to the inner mitochondrial membrane. Other work showed mitochondrial SCP levels increase only in situations where there is an increase in cholesterol levels. These findings strongly suggest that one of the functions of adrenal SCP is to participate in teh corticotropin-stimulated movement of cholesterol to the inner mitochondrial membrane for steroidogenesis.

Adrenal Glands↗
PubMed1984

Uptake of calcium by the endoplasmic reticulum of the frog photoreceptor.

We studied retinal photoreceptors of Rana pipiens by using techniques designed to investigate calcium localization. Particularly useful were methods in which intracellular sites of calcium uptake were detected by incubation of saponin-treated isolated retinas in calcium-containing media, with oxalate present as a trapping agent. With these procedures, cell compartments accumulate deposits, which can be shown to contain calcium by x-ray microanalysis. Calcium accumulation was prominent in the rough endoplasmic reticulum in the myoid region. In addition, deposits were observed in agranular reticulum and in certain Golgi-associated compartments of the myoid region, in mitochondria, in axonal reticulum, and in agranular reticulum of presynaptic terminals. Calcium was also detected in the endoplasmic reticulum of retinas fixed directly upon isolation, by a freeze-substitution method. The factors influencing accumulation of calcium in the endoplasmic reticulum were evaluated by a semiquantitative approach based on determining the relative frequency of calcium oxalate crystals under varying conditions. Calcium accumulation was markedly enhanced by ATP. Studies with a nonhydrolyzable ATP analogue (adenylyl- imidodiphosphate ) and with inhibitors of the sarcoplasmic reticulum Ca2+-Mg2+ ATPase (mersalyl and tetracaine) indicated that this ATP-dependent calcium uptake reflects an energy-dependent process roughly comparable to that in the sarcoplasmic reticulum.

Adenosine Triphosphate↗
PubMed1983

Distribution of membrane cholesterol of adrenal cortical cells after corticotropin stimulation.

Membrane cholesterol in adrenal cortical cells is enriched in the plasma membrane. Stimulation of isolated adrenal cortical cells with corticotropin leads to the production of corticosterone. At high levels of corticotropin, cholesterol for corticosterone synthesis arises by hydrolysis of cellular cholesteryl ester, whereas at lower levels of corticotropin cholesteryl ester levels are unchanged from control values and there is a decrease in plasma-membrane cholesterol levels.

Adrenal Cortex↗
PubMed1983

Pineal modulation of ACTH 1-17 effect upon murine corticosterone production.

In tests of corticosterone production in vitro, aqueous pineal homogenate (APH) modulates the effect of a short-chain ACTH analogue, ACTH 1-17, added to adrenals from different circadian stages. Adrenal and pineal glands from female B6D2F1 mice, standardized on staggered LD 12:12 regimens, were obtained at the same clock-hour from each room, in order to cover 6 different circadian stages. Adrenals from each circadian stage were bisected and incubated with APH from the same circadian stage (isophasic incubation) or from one of the other 5 circadian stages (heterophasic incubation). ACTH 1-17 (0.05 IU) was added to each incubation medium. After 4 hours of incubation at 37 degrees C with 95% O2 and 5% CO2, the media were stored at -20 degrees C until corticosterone RIA were done. APH was found to have a statistically significant modulatory effect upon the stimulation by ACTH 1-17 of adrenal corticosterone production in vitro. This APH effect changed rhythmically as a function of circadian stage from amplification over no effect to attenuation, as a so-called feed-sideward.

Adrenal Glands↗
PubMed1983

Circadian pineal modulation of pituitary effect on murine corticosterone in vitro.

An old controversy is resolved as a novel effect: In a rhythmic fashion, aqueous pineal homogenate (APH) enhances, attenuates or leaves unaffected the production of corticosterone by mouse adrenals incubated with pituitary media. All glands stem from the same circadian stage in these (isophasic) studies on 72 female CD2F1 mice, standardized for two weeks in L 0600-1800 and D 1800-0600. Every 4 hours during a 24-hour span, 12 mice were killed. Pineals were removed for the preparation of APH and stored at 4 degrees C. Hypothalami, pituitaries and adrenals were removed, bisected and placed in wells containing 1 ml Krebs-Ringer buffer (K), at 4 degrees C, until incubation. At each circadian stage, bisected adrenals were incubated with 95% O2 and 5% CO2 at 37 +/- 1 degree C for 5 hours, with K only or with the addition of 0.05 IU ACTH 1-17 or APH or with isophasic pituitary or hypothalamic preincubation media with and without APH or muscle. Media were stored at -20 degrees C until corticosterone RIA. A circadian rhythm (p less than 0.05) characterized corticosterone production after stimulation by the pituitary alone or with APH. The overall modulatory effect of APH is an increased circadian amplitude of adrenal corticosterone production, in response to the isophasic pituitary.

Adrenal Glands↗