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Biomedical subjects

J Rosenfeld

Publications and source records attributed to J Rosenfeld.

At least 19 recordsLinked to original sources
PubMed1994

Modulation of plasma arginine vasopressin during rehydration in the Bedouin goat.

When severely dehydrated Bedouin goats were allowed to drink to satiation their plasma arginine vasopressin concentration immediately dropped from a value of 19.9 +/- 9.4 pmol.l-1 to 9.4 +/- 3.9 pmol.l-1 (P < 0.05). It continued to drop further until a concentration of 1.8 +/- 2.9 pmol.l-1 was recorded, similar to that reported for goats allowed to drink freely. When the goats were shown the water but drinking was denied, plasma arginine vasopressin immediately dropped to 11.7 +/- 4.0 pmol.l-1 (P < 0.05) and further decreased to 10.0 +/- 4.8 pmol.l-1 5 min following their sighting the water. This level, however, was not sustained and 2 h after the initial drop the high pre-trial concentration of plasma arginine vasopressin was regained. Presumably, sighting of water by dehydrated goats induces an abrupt drop in their plasma arginine vasopressin level even before drinking commences. When rehydrated, by introducing water directly to the rumen, circumventing both the sensing of the water and the drinking proper, no immediate drop in the plasma arginine vasopressin concentration of the newly rehydrated goats was observed. A delayed drop in the plasma arginine vasopressin levels took place slowly, concurrently with the drop in osmolality and concentration of Na+ in the plasma. It is suggested that sighting of water by dehydrated goats is involved in the modulation of plasma arginine vasopressin.

Animals↗
PubMed1992

In-gel digestion of proteins for internal sequence analysis after one- or two-dimensional gel electrophoresis.

We examined the different steps necessary for the enzymatic digestion of proteins in the polyacrylamide matrix after gel electrophoresis. As a result, we developed an improved method for obtaining peptides for internal sequence analysis from 1-2 micrograms of in-gel-digested proteins. The long washing-lyophilization-equilibration steps necessary to eliminate the dye, sodium dodecyl sulfate, and other gel-associated contaminants that perturb protein digestion in Coomassie blue-stained gels have been replaced by washing for 40 min with 50% acetonitrile, drying for 10 min at room temperature, and then rehydrating with a protease solution. The washing and drying steps result in a substantial reduction of the gel slice volume that, when next swollen in the protease solution, readily absorbs the enzyme, facilitating digestion. The Coomassie blue staining procedure has also been modified by reducing acetic acid and methanol concentrations in the staining solution and by eliminating acetic acid in the destaining solution. The peptides resulting from the in-gel digestion are easily recovered by passive elution, in excellent yields for structural characterization. This simple and rapid method has been successfully applied for the internal sequence analysis of membrane proteins from the rat mitochondria resolved in preparative two-dimensional gel electrophoresis.

Amino Acid Sequence↗
PubMed1992

Antihypertensive effect of gamma-linolenic acid in spontaneously hypertensive rats.

The effects of chronic treatments of adult (aged 16-17 weeks) spontaneously hypertensive rats (SHRs) with different doses of gamma-linolenic acid (GLA) on blood pressure, heart rate, and body weight were studied. Twice-daily injection of SHRs with GLA lowered systolic blood pressure from 175 +/- 4 to 145 +/- 4 mm Hg within 1 week; systolic blood pressure in all three treated groups became stabilized in the normotensive range after 2 weeks of treatment. Control SHRs injected with olive oil showed only a transient decrease in systolic blood pressure on the third day. Heart rate and body weight were not affected by GLA treatment. Withdrawal of GLA treatment resulted in a rapid rise in systolic blood pressure within 1 day from 140 +/- 3 to 165 +/- 3 mm Hg, and it stabilized after 1 week at 191 +/- 5 mm Hg in the three experimental groups. A rapid increase in systolic blood pressure from 175 +/- 5 to 203 +/- 5 mm Hg was also observed in the control group treated with olive oil 1 day after the withdrawal of the treatment. Addition of aspirin (3 mg/kg) with the GLA treatment in olive oil abolished the antihypertensive effect of GLA. In contrast, once-daily treatment with GLA also lowered systolic blood pressure of the SHR, but blood pressure was still in the hypertensive range (170 +/- 6 mm Hg). Systolic blood pressure of control SHRs treated with olive oil was not affected. Plasma from untreated SHRs contained a small amount of GLA. One hour after the injection, the plasma level of GLA increased. We conclude that GLA when given twice daily is an effective antihypertensive agent in the SHR.

Animals↗
PubMed1991

The bed-wetting child. Current management of a frustrating problem.

Bed-wetting is a frustrating problem experienced by a significant number of children. It is the role of the physician to exclude serious underlying problems and, at the same time, educate the family concerning treatment options that may be best suited to their child. Once parents and child have a better understanding of the problem and realize that the outlook for nighttime bladder control is excellent, it is easier to start long-term care.

Child, Preschool↗
PubMed1990

Identification of the amino acid residues essential for the activity and the interconversion of the molecular forms of biliverdin reductase.

Biliverdin reductase (molecular form 1, EC 1.3.1.24, bilirubin:NAD(P)+ oxidoreductase) carries three thiol residues. Only one of them could be alkylated when a ratio N-ethylmaleimide (NEM)/mol enzyme's SH = 90 was used. The alkylation of this thiol group inhibited the conversion of molecular form 1 to its dimer, molecular form 3; however, it did not inhibit the enzymatic activity. At a ratio of NEM/enzyme's SH = 300, two thiol residues were alkylated and the activity of the enzyme was totally inhibited. The third thiol group could not be alkylated either by NEM or by iodoacetamide. Biliverdin as well as the co-substrate NADPH protected the thiol residue essential for the enzymatic activity from alkylation. Spectroscopic evidence was obtained that this thiol group binds covalently to the C-10 of biliverdin to form a rubinoid adduct. The presence of a lysine residue, which is also essential for the enzymatic activity, could be inferred from the fact that by reduction of the Schiff base formed by the enzyme with pyridoxal phosphate the catalytic activity was irreversibly abolished. The location of a lysine residue in the vicinity of the thiol group involved in the catalytic activity was evident when the enzyme was treated with o-phthalaldehyde. The inactivation of the enzymatic activity was coincident with the formation of the fluorescent isoindole derivative which originates when the thiol and epsilon-NH2 groups are located about 3 A apart. The presence of a positively charged ammonium ion in the vicinity of the NADPH binding site was inferred from the shifts in the UVmax of NADPH from 340 nm to 327 nm and of 3-acetyl NADPH from 360 nm to 348 nm when the pyridine nucleotides bind to the reductase. The involvement of arginine residues in the enzymatic activity was established by inhibition of the latter after reaction with butanedione. This inhibition was totally protected by NADPH but not by biliverdin. The similarity of the structural features of biliverdin reductase with those of several dehydrogenases is discussed.

Animals↗
PubMed1990

Cyclosporin treatment alters prostanoid and thromboxane production by rat isolated kidney mitochondria.

This study was designed to investigate the effects of chronic treatment with cyclosporin A (CSA) on the endogenous synthesis of prostanoids (PGs) and thromboxane (Tx) by renal isolated medullary and cortical mitochondria. The administration of CSA, dissolved in 10% ethanol in olive oil, to male Wistar rats (20 mg kg-1 day-1 i.p.) for 14 days resulted in alterations in mitochondrial biosynthesis of immunoreactive PGs. The endogenous synthesis of thromboxane by medullary and cortical mitochondria isolated from CSA-treated rats was significantly enhanced by 120 and 55%, respectively, whereas the synthesis of prostaglandin E2 by medullary mitochondria was reduced by 35%. The synthesis of prostaglandin F2 alpha and prostacyclin was not affected by CSA treatment. The conversion of exogenous arachidonic acid to PGs and Tx by cortical mitochondria isolated from CSA-treated rats was significantly increased. In addition, CSA treatment resulted in i) a reduced acylation of arachidonic acid into medullary phospholipids by 25% and into medullary and cortical triglycerides by 33 and 27%, respectively, and ii) an increase in cortical and medullary triglycerides. We suggest that the alterations in the endogenous mitochondrial production of PGs and Tx caused by CSA, may play a role in the impairment of membrane mediated functions.

Animals↗
PubMed1990

[Transformation, deformation and dysfunctioning in early interactions].

This article develops new perspectives that result from the early identification of dysfunctions in an infant's interaction with its environment. The authors develop research currently in progress concerning ways of screening interactive precursors possibly informative of the later emergence of autistic behavioral symptoms. After a review of articles concerning the screening of early signs of autism and of recent investigations regarding parent-infant interactions, they highlight their own therapeutic orientations. The methodology involves a "blind" sequential analysis of the interactions in home movies covering the period from birth to 2 years of age of 30 children divided into three groups: healthy, later autistic and those developing another pathology. This leads to theoretical hypothesis regarding the contingency and the creative inscription of chance events in the transformation of early interactions; the intersubjectivity and its deformations are considered, the observation of dysfunctions confronts the researcher with a freeze of empathy; what does this emotional lock-out mean? Appreciating the nature, the uniqueness, and the evolution of interactive dysfunctions can influence preventive strategies and lead to conceptualizing new theoretical and therapeutic models.

Attention↗
PubMed1989

Glioblastoma multiforme of the cerebellum in an elderly man. A case report.

Glioblastoma multiforme of the cerebellum is rare and comprises a small fraction of all glioblastomas. Eight-five cases have been reported in the literature to date. A 75 year old man is reported with a left cerebellar glioblastoma multiforme. The pathogenesis, course, treatment and prognosis are reviewed.

Aged↗
PubMed1989

The role of eicosanoids in cyclosporine nephrotoxicity in the rat.

Nephrotoxicity is the most troublesome complication of cyclosporine (CSA) therapy. The present study was designed to investigate the effects of chronic treatment with CSA on the 24-hr urinary excretion of prostanoids (PGs) and thromboxane (Tx) and on the renal function in the absence or presence of indomethacin. CSA administration to Wistar rats (20 mg/kg/day, i.p.) for 14 days caused a significant increase in plasma creatinine, blood urea nitrogen (BUN), urine osmolality, fractional excretion of sodium and potassium and a reduction in creatinine clearance (CCr) and urine volume. These changes were associated with a significant reduction in urinary excretion of PGE2 (21.1 +/- 3.3 vs 33.0 +/- 2.5 ng/24 hr) and PGF2 alpha (13.4 +/- 1.4 vs 27.9 +/- 3.8 ng/24 hr) and an increase in TxB2 (12.1 +/- 3.0 vs 4.6 +/- 0.5 ng/24 hr), and 6-keto PGF1 alpha (56.2 +/- 7.7 vs 27.7 +/- 1.9 ng/24 hr). However, the synthesis of TxB2 and 6-keto PGF1 alpha by renal medullary and cortical slices prepared from CSA treated rats was not different from values obtained for vehicle treatment. In contrast, PGE2 synthesis by cortical slices prepared from the CSA group was increased. A single injection of indomethacin (10 mg/kg) to vehicle and CSA treated rats resulted in a significant reduction in PGs and TxB2 excretion. This, was associated with a further reduction in CCr (0.81 +/- 0.06 vs 1.03 +/- 0.04 ml/min) and an increase in BUN (38.5 +/- 5.2 vs 28.2 +/- 1.4 mg%) only in the CSA group. We suggest that the vasodilating PGs attenuate the renal toxic effects induced by CSA.

Animals↗
PubMed1989

Molecular differences between rat-liver and rat-kidney biliverdin reductase. Implications for their in vivo regulation.

Rat-liver biliverdin reductase exists in two molecular forms. The major form 1 has a molecular mass of 34 kDa, while the minor form 2 has a molecular mass of 56 kDa. Form 1 was converted into a second major form (form 3) with a molecular mass of 68 kDa by a NAD+-dependent peroxisomal dehydrogenase which was induced under conditions of oxidative stress [Frydman, R. B., Tomaro, M. L., Awruch, J. & Frydman, B. (1984) Biochem. Biophys. Res. Commun. 121, 249]. Molecular form 1 from rat kidney was not affected by the dehydrogenase, and a structural explanation for this difference was therefore sought. Both form 1 biliverdin reductases, isolated from rat liver and kidney, were purified to homogeneity using affinity chromatography, FPLC and HPLC techniques. The homogeneous enzymes were found to be identical when compared by their HPLC retention times, amino acid compositions and electrophoretic behaviour on polyacrylamide gels under non-denaturing conditions and on SDS/polyacrylamide gels. On HPLC analysis the peptides resulting from the CNBr cleavage were found to be the same for both enzymes, when either the native enzymes or their thioethylpyridine derivatives were compared. When the HPLC fingerprints of the tryptic digests were compared, they were found to be very similar, except for a peptide eluting at 31.60 min in the liver digest and at 23.60 min in the kidney digest. When the enzyme from both origins was alkylated with 4-dimethylaminoazobenzene-4'-iodoacetamide and then digested with trypsin, the HPLC fingerprints of the alkylated cysteine-carrying peptides were almost identical, except for a peptide with a retention time of 19.03 min in the liver digest and of 18.19 min in the kidney digest. The liver reductase was not amenable to Edman degradation suggesting a block at the NH2-terminus; in the kidney enzyme, however, it was free and an NH2-terminal sequence of 12 amino acids could be determined. The liver enzyme was found to be more sensitive toward p-hydroxymercuriphenyl sulfonate than the kidney enzyme.

Alkylation↗
PubMed1989

Specular microscopy of hard contact lens wearers II.

Specular microscopy was done on 65 long-term hard contact lens (CL) wearers and controls matched for age, sex, race, and refractive error. There was no difference in mean endothelial cell size between the two groups, although median cell area was slightly smaller in the CL group. Standard deviation and coefficient of variation increased as the duration of total wearing time increased and were greater in the CL group, as was skewness. In 15 long-term hard CL wearers who had discontinued their CL wear, there was a trend towards persistence of pleomorphism and polymegathism of cells compared with non-contact lens (NCL) wearers, but there was a suggestion of recovery compared with those continuing to wear CLs matched for duration of wear.

Adult↗
PubMed1989

Cyclosporin: poorly tolerated in familial Mediterranean fever.

Cyclosporin is poorly tolerated in patients with amyloidosis due to familial mediterranean fever who are receiving colchicine. There is a high incidence of gastrointestinal side-effects and muscle weakness, both of which are reversible on stopping cyclosporin. Thus in patients with amyloidosis secondary to familial mediterranean fever treated with colchicine, the use of cyclosporin as an immunosuppressive agent may be restricted.

Adult↗
PubMed1988

Albumin determination in frozen urines--underestimated results.

Albumin determination by radioimmunoassay in fresh and frozen urine collections from 73 patients were performed. The values for albumin in fresh urines were 1-200 mg/24 h and were significantly higher (p less than 0.001) than the corresponding values in urines frozen for seven days (40.7 mg/24 h +/- 5.0 vs. 32.0 mg/24 h +/- 4.3). Similar results were obtained for protein determination, using turbidimetry, in urine collections from 45 proteinuric patients. Iodinated human albumin added to urine specimens was higher (p less than 0.001) in the pellets from frozen urines compared to urines kept at 4 degrees C for 1 and/or 7 days. By contrast, the radioactivity in the pellet of fresh urines kept at 4 degrees C for 1 or 7 days did not show any significant change. We suggest that freezing results in a partial albumin and protein sedimentation. Thus, determination of albumin in frozen urine specimens underestimates the real value by about 20%. This underestimation will limit our ability to diagnose borderline cases of microalbuminuria.

Albuminuria↗
PubMed1988

Neurofilament antigens in acrylamide neuropathy.

After repeated exposure, acrylamide (AC) produces degeneration of distal axons. Because neurons whose axons have been injured (e.g. by axotomy) show alterations in their structural and chemical properties, the present study was designed to differentiate the direct effects of AC intoxication from neuronal responses secondary to axonal injury caused by AC. Rats were given AC as either a single high dose (75 mg/kg), or as daily intraperitoneal injections (30 mg/kg, six days per week for four weeks). Dorsal root ganglia of the fifth lumbar level, L5, were examined using a variety of monoclonal antibodies directed against nonphosphorylated (2-135) and phosphorylated (03-44, 06-17, 07-05) epitopes of 145 and 200 kilodalton neurofilament proteins. In control rats, antibody 2-135 stained axons and neuronal cell bodies; antibodies against phosphorylated epitopes of neurofilaments stained only axons distal to the glomerulus. Following chronic AC intoxication, all three antibodies directed against phosphorylated epitopes of neurofilaments (particularly 07-05) demonstrated intense immunoreactivity in 20-30% of neuronal cell bodies. In addition, the glomerular region of these axons was stained. Electron microscopy revealed many chromatolytic cells containing few neurofilaments. In contrast, a single high dose of AC produced no abnormal staining of neuronal cell bodies at a time when slow axonal transport was impaired. Our findings are compared to those observed following axotomy and to those occurring in aluminum-intoxicated rabbits, two experimental disorders in which altered distributions of phosphorylated filaments have been documented.

Acrylamides↗