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D Russo

Publications and source records attributed to D Russo.

At least 181 records · Page 10Linked to original sources
PubMed1992

Role of amino acids 261-418 in proteolytic cleavage of the extracellular region of the human thyrotropin receptor.

Previous in vivo cross-linking studies of TSH to the recombinant TSH receptor revealed that the receptor exists at least in part as a single chain glycoprotein of approximately about 100 kilodaltons (kDa), with intramolecular disulfide bonds. TSH also binds to a 54-kDa amino-terminal fragment of the TSH receptor (cleaved up-stream of amino acid residue 317). In the present study in order to better understand the structure of the TSH receptor, we covalently cross-linked radiolabeled TSH to six TSH-LH receptor extracellular region chimeras and the wild-type TSH receptor expressed on Chinese hamster ovary cells in vivo. In these chimeras, different regions of the TSH receptor were substituted with the homologous regions of the LH receptor. When analyzed under nonreducing conditions by polyacrylamide gel electrophoresis, the TSH-cross-linked products were similar to all TSH-LH receptor chimeras and the wild-type receptor. In contrast, differences among the receptors were noted when the TSH-cross-linked products were examined under reducing conditions. With the exception of two chimeras, as noted previously with the wild-type receptor, two TSH-cross-linked products were observed, representing TSH cross-linked to a holoreceptor of about approximately 100 kDa and a fragment of the receptor of about approximately 54 kDa. However, in the two chimeras in which both domains D and E (amino acids 261-418) of the TSH receptor were substituted, only the holoreceptor and not the smaller fragment was detected. Substitution of domains ABC (amino acids 1-260) did not prevent proteolytic cleavage of the TSH receptor. In conclusion, amino acids 261-418 are necessary for proteolytic cleavage of the extracellular region of the human TSH receptor.

Endopeptidases↗
PubMed1992

Studies on the role of amino acids 38-45 in the expression of a functional thyrotropin receptor.

We previously reported that deletion or substitution of a unique eight-amino acid tract (residues 38-45) in the extracellular domain of the human TSH receptor led to the loss of specific ligand binding to the surface of transfected cells. In the present study we analyzed this region in more detail. Using site-directed mutagenesis of the TSH receptor cDNA, we substituted amino acid residues 38-45, either in three overlapping groups of four amino acids each or individually. The resultant TSH receptor mutant cDNAs were stably transfected into Chinese hamster ovary cells, and the cells were tested for their TSH-binding ability. Our data demonstrate that amino acid residues 38-40 and 42-45 in this region of the human TSH receptor can be substituted without alteration in receptor function and are, therefore, not critical in forming or maintaining the TSH-binding site. However, substitution of Cys41, either alone or together with adjacent amino acids, leads to the loss of TSH binding to its receptor. These data suggest a central role for the amino acid in position 41 in preserving the biological function of the TSH receptor.

Amino Acid Sequence↗
PubMed1992

Multidrug resistance (MDR) gene expression in acute non lymphoblastic leukemia: sequential analysis.

Sequential evaluation of P-glycoprotein expression was performed in 29 patients with acute nonlymphoblastic leukemia using immunocytochemistry with the C219 antibody. At diagnosis, 32% of the patients exhibited more than 5% of the P-gp(+) leukemic cells. Under chemotherapy, 62% of the patients eventually expressed a subset of P-gp positive leukemic cells. After conventional doses of cytosine-arabinoside (Ara-C) and daunorubicin or mitoxantrone, positive P-gp cells were noted in 65% of the cases. This percentage was significantly higher (p = 0.002) than the proportion of positive cases (15%) observed after regimens containing either intermediate doses of Ara-C or cyclosporine A, a P-gp modulator.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

The place of loop diuretics in the treatment of acute and chronic renal failure.

Loop diuretics (furosemide, bumetanide, muzolimine, piretamide, torasemide) are powerful drugs capable of increasing sodium excretion and urine output even when renal function is markedly impaired. In patients with chronic renal failure (CRF), loop diuretics may be given to control extracellular volume (ECV) expansion responsible for hypertension. But the use of loop diuretics in chronic uremia is mostly helpful when impaired renal function co-exists with nephrotic syndrome or chronic heart failure. Due to their powerful natriuretic activity, loop diuretics have been administered also to patients on maintenance dialysis to reduce the frequency of and/or to curtail dialysis time. In this condition, however, the increase of sodium and water excretion is very limited; whereas the use of diuretics in high dosage is not devoid of risky side effects such as neurologic lesions, cramps, deafness, weakness, muscle pain. In some patients with oliguric form of acute renal failure (ARF), loop diuretics increase sodium excretion and urine output. They do not affect the mortality rate for ARF but may facilitate the treatment of patients by reverting an oliguric form to a non-oliguric form of ARF.

Acute Kidney Injury↗
PubMed1991

Eleven amino acids (Lys-201 to Lys-211) and 9 amino acids (Gly-222 to Leu-230) in the human thyrotropin receptor are involved in ligand binding.

Our previous studies involving chimeric thyrotropin-lutropin/choriogonadotropin (TSH-LH/CG) receptors suggest that multiple segments spanning the entire extracellular domain of the human TSH receptor contribute to the TSH binding site. Nevertheless, the mid-region (segment C, amino acid residues 171-260) of the receptor extracellular domain is particularly important in TSH binding. In the present studies, we constructed seven new chimeric receptors in order to analyze segment C in further detail. Seven small segments spanning segment C of the TSH receptor were replaced with the counterpart of the rat LH/CG receptor. These mutant receptors were stably introduced into Chinese hamster ovary cells and were tested for hormone binding and cAMP responsiveness to hormone stimulation. The results indicate that 11 amino acids of the TSH receptor (Lys-201 to Lys-211) and the corresponding region of the LH/CG receptor (Thr-202 to Ile-212) are important for specific TSH and human CG binding, respectively. In addition, nine amino acids of the TSH receptor (Gly-222 to Leu-230) are also involved in TSH binding. A further conclusion from these data is that TSH and human CG bind to partially overlapping sites on their respective receptor molecules.

Amino Acid Sequence↗
PubMed1991

Thyrotropin-luteinizing hormone/chorionic gonadotropin receptor extracellular domain chimeras as probes for thyrotropin receptor function.

To define the sites in the extracellular domain of the human thyrotropin (TSH) receptor that are involved in TSH binding and signal transduction we constructed chimeric thyrotropin-luteinizing hormone/chorionic gonadotropin (TSH-LH/CG) receptors. The extracellular domain of the human TSH receptor was divided into five regions that were replaced, either singly or in various combinations, with homologous regions of the rat LH/CG receptor. The chimeric receptors were stably expressed in Chinese hamster ovary cells. The data obtained suggest that the carboxyl region of the extracellular domain (amino acid residues 261-418) and particularly the middle region (residues 171-260) play a role in signal transduction. The possibility is also raised of an interaction between the amino and carboxyl regions of the extracellular domain in the process of signal transduction. With respect to hormone binding, substitution of the entire extracellular domain of the LH/CG receptor for the corresponding region of the TSH receptor resulted in high-affinity human CG binding with complete loss of TSH binding. Surprisingly, however, there was at least one chimera with a substitution at each of the five domains that still retained high-affinity TSH binding. Substitution of residues 1-170 of the TSH receptor with the corresponding region of the LH/CG receptor was associated with the retention of high-affinity TSH binding but ligand specificity was lost in that TSH and human CG could interact functionally with the receptor. In summary, these studies suggest that the middle region and carboxyl half of the extracellular domain of the TSH receptor are involved in signal transduction and that the TSH-binding region is likely to span the entire extracellular domain, with multiple discontinuous contact sites.

Animals↗
PubMed1991

Photodynamic therapy of the canine peritoneum: normal tissue response to intraperitoneal and intravenous photofrin followed by 630 nm light.

A toxicity study was performed in a canine model to explore the feasibility of using intraperitoneal photodynamic therapy for patients with peritoneal carcinomatosis. Dogs received 1.25 mg/kg Photofrin II both intravenously (48 hours) and intraperitoneally (2 hours) before intraperitoneal light treatment. The entire peritoneal surface was illuminated with 0.57-0.74 J/cm2 of red light (630 nm). Thirteen dogs were treated: 4 control and 9 full treatment. Of the fully treated dogs, 5 received a single treatment and 4 received 3 treatments. The dogs were evaluated clinically and pathologically for immediate (4 days) and late (60 days) side effects. All animals tolerated the treatment without significant morbidity. Postoperative blood tests were normal except for low lymphocyte counts and elevated liver transaminases, both of which normalized rapidly. Histopathologically, there was approximately a 50% incidence of mild inflammatory peritoneal response. This study provides the basis for a Phase I human trial.

Animals↗
PubMed1991

Granulocyte-macrophage colony-stimulating factor in acute non-lymphocytic leukemia before and after chemotherapy.

The introduction of hematopoietic growth factors into the management of leukemia can influence the outcome of treatment in several ways, depending on the sensitivity and the response of normal and leukemic cells. In this paper we report on the effects of the administration of Escherichia coli-produced, human recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) in 15 adult patients with acute nonlymphocytic leukemia (ANLL) resistant to first-line treatment or in relapse. GM-CSF was given at a dose of 5-10 micrograms/kg/day as a 6-h i.v. infusion, prior to chemotherapy (CHT) (for 7 days) and after CHT (until evidence of failure or of remission). In the pre-CHT period there was a clear trend towards an increase of circulating neutrophils (PMN) and/or blast cell count (median 0.3 vs. 1.0 x 10(9)/l for PMN, and 0.5 vs. 2.3 for blast cells). After chemotherapy, in the patients who achieved complete remission (CR), the median time to a PMN count greater than 0.5 x 10(9)/l and greater than 1 x 10(9)/l was 16 days (range 13-27) and 19 days (range 13-42) respectively. The outcome of treatment was CR for 8/15 (53%), death during induction for 3/15 (20%), and failure for 4/15 (27%). All failures occurred in patients with an increase of blast cell count during pre-CHT GM-CSF administration. Toxicity and side effects were minor, apart from an acute respiratory syndrome that developed twice in the same patient, at doses of 10 and 3 micrograms/kg/day. These data suggest that investigation of GM-CSF in the treatment of ANLL is worth pursuing, with special attention to GM-CSF effects prior to chemotherapy.

Adult↗
PubMed1991

Lack of relationship between 3',5'cyclic adenosine monophosphate desensitization and thyrotropin receptor down regulation in the rat thyroid cell line FRTL5.

We studied the cAMP response and radioiodinated TSH binding in the FRTL5 rat thyroid cell line after chronic exposure to TSH. In parallel experiments, continuous exposure to TSH induced both a decrease in the cellular cAMP responsiveness to a second acute stimulation by thyrotropin (desensitization) and a reduction in 125I-TSH cellular binding (down-regulation). These two processes appeared to differ in that: a) cAMP desensitization was maximal (45-55% inhibition in comparison to control cells) after 24 h of preexposure to TSH; on the contrary, a loss of the TSH binding to thyroid cells was detected only after 24 h and was maximal (55-65% lower than control cells) after 48 h of preexposure to TSH; b) a different dependence on the TSH dose was observed for cAMP desensitization and TSH down-regulation: the former was maximal at 10 microU/ml of TSH, the latter only at 10 mU/ml of TSH; c) recovery from cAMP desensitization was detected 3 h after TSH withdrawal and was fully achieved at 24 h, whereas the recovery from the TSH receptor down-regulation was not evident for up to 24 h and a full recovery obtained only at 72 h; d) the use of cAMP analogues proved that, unlike desensitization, TSH receptor down-regulation is a cAMP dependent process. These findings support the concept that different patterns of response to prolonged stimulation with TSH, an earlier and cAMP-independent process (desensitization) and a later cAMP-dependent mechanism (down-regulation), occur in the rat thyroid cell.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Patient-controlled analgesia in children and adolescents: a randomized, prospective comparison with intramuscular administration of morphine for postoperative analgesia.

A randomized, prospective trial of patient-controlled analgesia (PCA), that is, a method of analgesia administration involving a computer-driven pump activated by patients to receive small doses within defined limits was performed in 82 children and adolescents after major orthopedic surgery to compare (1) intramuscularly administered morphine, (2) PCA morphine and (3) PCA morphine with a low-dose continuous morphine infusion (PCA-plus). Patients receiving PCA and PCA-plus had lower pain scores and greater satisfaction than patients receiving intramuscularly administered morphine. The three groups used equal amounts of morphine and most measures of recovery were identical in the groups. In particular, PCA and PCA-plus did not increase the incidence of opioid-related complications, and patients receiving PCA-plus were less sedated than patients receiving intramuscular therapy. We conclude that PCA and PCA-plus are safe and effective methods of pain relief in children and adolescents after orthopedic surgery, are better accepted than intramuscular injections, and do not increase perioperative morbidity.

Adolescent↗
PubMed1991

Renal functional reserve: its significance in normal and salt depletion conditions.

The aim of this study was the evaluation, in healthy subjects, of the renal functional reserve (RFR), that is, the GFR increase induced by a combined infusion of amino acids (AA) and dopamine (D), in conditions of extracellular volume depletion caused by diuretic administration. In particular, this study was undertaken: a) to evaluate whether and to which extent, AA + D can reverse the functional GFR impairment induced by salt depletion, without volume restoration; b) to study whether any relationship may be found between the GFR in normal condition (the so-called "resting" GFR), and/or the renal functional reserve and the GFR impairment induced by salt depletion, in order to understand the role of both "resting" GFR and RFR in the degree of renal dysfunction induced by salt depletion. In control conditions the i.v. infusion of AA + D significantly increased RPF (+ 41% vs. baseline period) with a mean absolute increase of 211 ml/min. A similar pattern was observed in GFR behavior (+31.5% with 34 ml/min of mean absolute increase). A significant inverse exponential relationship was observed between GFR before AA + D i.v. infusion ("resting" GFR) and renal functional reserve (P less than 0.05), suggesting that, in normal conditions, these inversely related parameters may widely vary according to the tone of the glomerular arterioles. Following salt depletion, we observed a variable degree of GFR impairment. Both GFR and RPF were significantly decreased (-25.9%, P less than 0.05 and -29%, P less than 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

The expression of the multidrug resistance-associated glycoprotein in B-cell chronic lymphocytic leukaemia.

The expression of the multidrug resistance (MDR)-associated 170 kDa glycoprotein (p170) was investigated in 63 cases of B-cell chronic lymphocytic leukaemia (CLL), with two monoclonal antibodies (MRK-16 and C-219). By immunocytochemistry with MRK-16 (63 cases), the great majority of the cells was positive, with a weak reaction in 61% of cases and a strong reaction in 39% of cases. By flow cytometry, the proportion of positive cells was 39 +/- 25% with MRK-16 (63 cases), and 23 +/- 22% with C-219 (36 cases). The expression of p170 in leukaemic B-lymphocytes suggests that also in B-CLL the development of MDR can have some therapeutic relevance. By either method the proportion of positive cells was not related to prior treatment, time from diagnosis, absolute lymphocyte count, and clinical stage (Rai's and workshop classifications), but 12 patients who were under treatment with alpha-interferon had more positive cells than the other ones.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Binding domains of stimulatory and inhibitory thyrotropin (TSH) receptor autoantibodies determined with chimeric TSH-lutropin/chorionic gonadotropin receptors.

We examined the relative effects of thyrotropin (TSH) and TSH receptor autoantibodies in the sera of patients with autoimmune thyroid disease on three TSH-lutropin/chorionic gonadotropin (LH/CG) receptor extracellular domain chimeras. Each chimera binds TSH with high affinity. Only the chimera with TSH receptor extracellular domains ABC (amino acids 1-260) had a functional (cAMP) response to thyroid stimulatory IgG. The chimeras with TSH receptor domains CD (amino acids 171-360) and DE (amino acids 261-418) were unresponsive. The lack of response of the chimera with TSH receptor domains DE was anticipated because it fails to transduce a signal with TSH stimulation, unlike the other two chimeras. A different spectrum of responses occurred when the TSH-LH/CG chimeras were examined in terms of autoantibody competition for TSH binding. IgG with TSH binding-inhibitory activity when tested with the wild-type TSH receptor also inhibited TSH binding to the chimera with TSH receptor domains DE. Dramatically, however, these IgG did not inhibit TSH binding to the chimera with TSH receptor domains CD, and had weak or absent activity with the chimera with TSH receptor domains ABC. Chimeras with TSH receptor domains ABC and DE were equally effective in affinity-purifying IgG with thyroid-stimulatory and TSH binding-inhibitory activities. Nonstimulatory IgG with TSH binding-inhibitory activity inhibited the action of stimulatory IgG on the wild-type TSH receptor, but not with the chimera containing TSH receptor domains ABC. In summary, TSH receptor autoantibodies and TSH bind to regions in both domains ABC and DE of the TSH receptor extracellular region. Stimulatory and inhibitory TSH receptor autoantibodies, as well as TSH, appear to bind to different sites in domains ABC, but similar sites in domains DE, of the receptor. Alternatively, TSH and the different TSH receptor antibodies bind with differing affinities to the same site in the ABC region.

Autoantibodies↗
PubMed1991

The biological activity of bovine and human thyrotropin is differently affected by trypsin treatment of human thyroid cells: thyroid-stimulating antibody is related to human thyrotropin.

Pretreatment of cultured human thyroid cells with trypsin decreased the cAMP response to bovine TSH (bTSH) (by 50-60%). In striking contrast, in trypsin treated cells the cAMP stimulation by both human TSH (hTSH) and thyroid-stimulating antibodies (TSab) was unimpaired, indicating a similar behavior for these two stimulators. The effect of trypsin on inhibiting cAMP stimulation by bTSH was: 1) dose dependent; 2) present at a trypsin concentration as low as 3.3 mg/L; 3) fully reversible within 24 h after removal of the enzyme. In accordance with the altered biological activity in human thyroid cells exposed to trypsin the binding of labeled bTSH was reduced (about 40%). On the contrary, in the same cells, the binding of labeled human TSH was enhanced (about 3-fold). The cAMP response to cholera toxin and forskolin was unaffected in trypsin treated cells, indicating that the tryptic treatment did not alter any other component of the adenylate cyclase complex. The medium obtained from trypsin-treated human thyroid cells was able to neutralize the biological activity of bTSH but not that of hTSH or TSab. Our study demonstrates that in human thyroid cells: 1) trypsin impaires bovine, but not human TSH or TSab biological activity; 2) bovine and human TSH may bind to different components of the TSH receptor.

Animals↗
PubMed1991

Site-directed mutagenesis of the human thyrotropin receptor: role of asparagine-linked oligosaccharides in the expression of a functional receptor.

We studied the role of glycosylation in the expression of a functional human TSH receptor. Oligonucleotide-directed mutagenesis was used to replace, separately or together, the Asn codons with Gln in each of the six potential glycosylation sites in the receptor. Recombinant wild-type and mutated TSH receptors were stably expressed in Chinese hamster ovary cells. High affinity TSH binding and the cAMP response to TSH stimulation were abolished in the receptor mutated at Asn77 as well as in the receptor mutated at all six potential glycosylation sites. In the receptor mutated at Asn113, the affinity of TSH binding was markedly decreased (Kd, 2.6 x 10(-8) 3.3 x 10(-10) M in the wild-type receptor). This affinity was too low to permit the transduction of a signal, as measured by an increase in intracellular cAMP generation. Substitution of Asn at positions 99, 177, 198, and 302 did not appreciably affect the affinity of the TSH receptor for TSH binding or its ability to mediate an increase in intracellular cAMP levels. Therefore, either these four potential glycosylation sites are not glycolysated, or alternatively, oligosaccharide chains at these positions do not play a major role in the folding, intracellular trafficking, stability, or expression of a functional receptor on the cell surface. Conversely, our data suggest that N-linked glycosylation of Asn77 and Asn113 does play a role in the expression of a biologically active TSH receptor on the cell surface.

Animals↗
PubMed1991

Signal transduction by the human thyrotropin receptor: studies on the role of individual amino acid residues in the carboxyl terminal region of the third cytoplasmic loop.

We observed previously that the carboxyl-terminal region of the third loop of the TSH receptor (amino acid residues 617-625) is important in signal transduction. To analyze this region in more detail, in the present study we used site-directed mutagenesis to substitute, on an individual basis, the seven amino acids previously mutated as a group. These amino acids are either charged residues or potential phosphorylation sites. Six of the mutant TSH receptors with individual amino acid substitutions bound TSH with high affinity and displayed a cAMP response to TSH stimulation similar to the wild-type TSH receptor. The mutant receptor TSH-R-Gly625 (Arg----Gly) did not transduce a signal, but these results are noninformative because of the loss of high affinity TSH binding. The present data indicate that for each of the six informative amino acid substitutions, the individual residues are not critical for signal transduction. A corollary of this conclusion is that in the important carboxyl-terminal region of the third cytoplasmic loop of the TSH receptor multiple amino acid residues function as a unit.

Amino Acid Sequence↗
PubMed1991

A new structural model for the thyrotropin (TSH) receptor, as determined by covalent cross-linking of TSH to the recombinant receptor in intact cells: evidence for a single polypeptide chain.

The most widely held model for the human TSH receptor is of holoreceptor of 80 kDa with two subunits of approximately 50 and 30 kDa linked by disulfide bridges, with the former subunit containing the major hormone-binding site. We reexamined this model by covalently cross-linking radiolabeled TSH to the recombinant human TSH receptor stably expressed in Chinese hamster ovary (CHO) cells. When cross-linking was performed after the preparation of CHO membranes, analysis of hormone-receptor complexes under reducing and nonreducing conditions provided results supporting the two-subunit TSH receptor model. In contrast, however, cross-linking of TSH to the TSH receptor in intact CHO cells before membrane preparation revealed, even under reducing conditions, an approximately 100-kDa receptor as well as an approximately 54-kDa hormone-binding subunit. The approximately 100-kDa holoreceptor size is consistent with the size of the TSH receptor, as predicted from its derived amino acid sequence. The proportions of the approximately 100-kDa TSH receptor and the 54-kDa fragment varied in different experiments, suggesting the occurrence of proteolytic cleavage. Cross-linking of radiolabeled TSH to intact cells expressing a mutant TSH receptor (TSHR-D1) lacking amino acids 317-366 localized the proteolytic cleavage site to just up-stream of amino acid residue 317. In summary, the present data obtained by cross-linking TSH to recombinant human TSH receptors in intact cells provides evidence that the receptor exists in vivo as an approximately 100-kDa glycoprotein with a single polypeptide chain with intramolecular disulfide bridges.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗