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Biomedical subjects

G Gallo

Publications and source records attributed to G Gallo.

At least 73 records · Page 4Linked to original sources
PubMed1998

Localized sources of neurotrophins initiate axon collateral sprouting.

The sprouting of axon collateral branches is important in the establishment and refinement of neuronal connections during both development and regeneration. Collateral branches are initiated by the appearance of localized filopodial activity along quiescent axonal shafts. We report here that sensory neuron axonal shafts rapidly sprout filopodia at sites of contact with nerve growth factor-coated polystyrene beads. Some sprouts can extend up to at least 60 micro(m) through multiple bead contacts. Axonal filopodial sprouts often contained microtubules and exhibited a debundling of axonal microtubules at the site of bead-axon contact. Cytochalasin treatment abolished the filopodial sprouting, but not the accumulation of actin filaments at sites of bead-axon contact. The axonal sprouting response is mediated by the trkA receptor and likely acts through a phosphoinositide-3 kinase-dependent pathway, in a manner independent of intracellular Ca2+ fluctuations. These findings implicate neurotrophins as local cues that directly stimulate the formation of collateral axon branches.

Actins↗
PubMed1998

L-carnitine esters as "soft", broad-spectrum antimicrobial amphiphiles.

A new class of antimicrobial, "soft", quaternary ammonium l-carnitine esters, of the type (CH3)3N+-CH2-CHOCO(R1)-CH2-COO(R2) Cl-, has been designed, with R1 and R2 being in general long-chain alkyl substituents. The series shows good activity against a wide range of bacteria, yeasts, and fungi. Lipophilicity has been measured by RP-HPLC method to give the logarithm of the experimental capacity factor (log k'), and a quantitative relationship has been determined between log k' and the theoretical partition coefficient (CLOGP); also, bond-dipole descriptors have been introduced into calculations by accounting for polar moieties present within the apolar cores of the molecules, giving a more refined calculated capacity factor (log k'calcd). Finally the latter has been related to the antimicrobial activity (MIC values). The proposed models are predictive for the best broad-spectrum antimicrobial compound within the series.

Anti-Bacterial Agents↗
PubMed1998

Axon guidance: GTPases help axons reach their targets.

During development and regeneration of the nervous system, axons must correctly navigate to their specific targets through a complex molecular environment. Recent work has shed light on how GTPases of the Ras family are involved in transducing extracellular signals into responses that lead to directed neurite outgrowth.

Animals↗
PubMed1998

Familial idiopathic myelofibrosis and multiple hemangiomas.

Idiopathic myelofibrosis (MF) is a rare disease in childhood. The clinical spectrum is very variable. Familial idiopathic MF has been recorded exceptionally. In previous reports idiopathic MF in childhood has been described in association with congenital anomalies and with chromosome abnormalities, although neither of these features have been reported in a familial context. We report two sisters with idiopathic MF and multiple eruptive hemangiomas. Details of their clinical signs, laboratory findings, and histologic features are described.

Adolescent↗
PubMed1998

QSAR models for discriminating between mutagenic and nonmutagenic aromatic and heteroaromatic amines.

In a previous article, we demonstrated that the structure-activity relationship model for the mutagenic potency of aromatic amines is different from that for discriminating between mutagens and nonmutagens. In this work, we present further analyses on the molecular determinants of the mutagenicity of aromatic amines. Based on the use of various methodological approaches, our results indicate that mutagenic activity is influenced by different molecular characteristics in different subclasses of aromatic amines. Thus, the general lesson of this article is that 1) in genetic toxicology, it is necessary to separately investigate the structure-activity relationships for discrimination between positive and negative chemicals, and the structure-activity relationships for the potency of the positive chemicals; 2) in structure-activity studies, it is necessary to investigate the degree of homogeneity (congenericity) of apparently similar chemicals in order to assess and describe the various mechanisms of action that may be elicited by the chemicals.

Amines↗
PubMed1998

In vitro and in vivo effects of heavy metals on mussel digestive gland hexokinase activity: the role of glutathione.

Hexokinase (E.C. 2.7.1.1), the enzyme responsible for glucose phosphorylation to G-6P, is inactivated by SH reagents and oxyradicals, and its inhibition has been involved in heavy metal toxicity in mammalian systems. In this work, the possibility that hexokinase activity could be affected by both heavy metal binding and oxidative stress conditions also in mussel tissues (Mytilus galloprovincialis Lam.) was investigated. The results obtained in vitro demonstrate that heavy metals inhibited digestive gland hexokinase (with Cd2+ > Cu2+ > Hg2+ > Zn2+ > Pb2+) and suggest a role for GSH in the protection against the heavy metal effects. Hexokinase activity was also reduced by addition of iron/ascorbate, indicating a susceptibility of the enzyme to metal-mediated oxyradical production. The effects of Cu2+ treatment (3 days, 40 micrograms l-1 per animal) on hexokinase activity and on the GSH/GSSG status were then evaluated in mussels exposed to a cycle of air exposure/reimmersion. In Cu-exposed mussels, a significant decrease in hexokinase activity and a parallel reduction in tissue GSH levels were observed, suggesting that the two effects of metal treatment could be related; however, hexokinase activity progressively recovered during air exposure and reimmersion, whereas the level of GSH showed a further decrease during air exposure followed by recovery after reimmersion. The in vitro results therefore indicate that mussel digestive gland hexokinase is susceptible to inactivation by heavy metal binding and suggest a role for GSH in the protection against the effects of heavy metals. The effects of copper were confirmed by the results obtained in vivo. The possible relationship between hexokinase activity and the level of GSH in the digestive gland of control and Cu-exposed mussels during air exposure and reimmersion are discussed, taking into account the balance between pro-oxidant and antioxidant processes at different stages of exposure.

Animals↗
PubMed1998

Involvement of microtubules in the regulation of neuronal growth cone morphologic remodeling.

The guidance of nerve fibers depends on the constant protrusion, movement, and retraction (i.e., remodeling) of growth cone lamellae and filopodia. We used drugs that interfere with the dynamics of microtubules to investigate the role of microtubules in the remodeling of larval amphibian spinal cord neuronal growth cones. Vinblastine (8-100 nM), taxol (10 nM), and nocodazole (330 nM) altered microtubule distributions in growth cones and decreased the percentage of lamellar perimeter undergoing remodeling, while not affecting the rates of lamellar protrusion and retraction. Also, 8-20 nM vinblastine caused temporary losses of the continuity of the originally fan-shaped lamella, resulting in two or more lamellae at the growth cone. At higher concentrations of microtubule drugs, the originally fan-shaped lamella broke up into separate smaller lamellae followed by the centrifugal displacement from the base of the growth cone and eventual collapse of the resultant lamellae. Low doses of cytochalasin B prevented the centrifugal displacement of lamellae in response to microtubule drugs. During microtubule drug-mediated loss of growth cone lamellae, some filopodia were observed to elongate to greater than normal lengths. Similarly, exposure to 20 nM vinblastine resulted in an increase in filopodial length but not filopodial number. As evidenced by DiOC6(3) staining, 8-20 nM vinblastine altered the distribution of membranous organelles within growth cones, suggesting that the effects of microtubule drugs on growth cones may be mediated in part by alterations in organelle localization. Our data show that microtubules are involved in the maintenance and regulation of lamellar and filopodial structures at the neuronal growth cone. These findings have implications for the mechanisms by which growth cones are guided during development and regeneration.

Actins↗
PubMed1997

The trkA receptor mediates growth cone turning toward a localized source of nerve growth factor.

We have developed an in vitro system for studying the interaction of chick dorsal root ganglion neuronal growth cones with a localized source of nerve growth factor (NGF) covalently conjugated to polystyrene beads. Growth cones rapidly turned and migrated under NGF-coated beads in a process that involved the initial formation of persistent contact with a bead, followed by directed flow of cytoplasm toward the point of contact. A role for the local activation of the high-affinity NGF receptor trkA was suggested by a strong inhibition of the turning response by (1) the addition of an antibody against the extracellular portion of trkA, (2) the elevation of the background concentration of NGF to saturate trkA, or (3) the presence of a concentration of the drug K252a that inhibits trkA activation. NGF binding to the pan-neurotrophin receptor p75 is also involved but is not required for turning. These data show a new role for both the trkA and the p75 receptors: the mediation of local events in the guidance of nerve growth cones.

Animals↗
PubMed1997

Variant-sequence transthyretin (isoleucine 122) in late-onset cardiac amyloidosis in black Americans.

BACKGROUND: After the age of 60, isolated cardiac amyloidosis is four times more common among blacks than whites in the United States; 3.9 percent of blacks are heterozygous for an amyloidogenic allele of the normal serum carrier protein transthyretin in which isoleucine is substituted for valine at position 122 (Ile 122). We hypothesized that the high prevalence of transthyretin Ile 122 is at least partially responsible for the increased frequency of senile cardiac amyloidosis among blacks. METHODS: Paraffin blocks of cardiac tissue were obtained from an earlier study of 52,370 autopsies in Los Angeles and were examined by immunohistochemical and DNA analyses. Samples were available from 32 of 55 blacks and 20 of 78 whites over 60 years of age with isolated cardiac amyloidosis and from two control groups (228 cases). RESULTS: Transthyretin amyloidosis was identified in 31 of the 32 cardiac-tissue samples from the black patients and in 19 of the 20 samples from the white patients. Six of the 26 analyzable DNA samples (23 percent) from the black patients and none of the 19 samples from the white patients were heterozygous for the Ile 122 variant. Four of 125 DNA samples obtained at autopsy (3.2 percent) from a second, more recent, age-matched cohort of blacks without amyloidosis at the same institution were heterozygous for the transthyretin Ile 122 allele. On reexamination the cardiac tissue from these four patients contained small amounts of amyloid not detected at the initial autopsies. All subjects with the Ile 122 variant had ventricular amyloid. CONCLUSIONS: The assessment of elderly black patients with unexplained heart disease should include a consideration of transthyretin amyloidosis, particularly that related to the Ile 122 allele.

Aged↗
PubMed1997

Results of a BFM-based protocol for the treatment of childhood B-non-Hodgkin's lymphoma and B-acute lymphoblastic leukemia in Argentina.

PURPOSE: To report the feasibility and results of a study based on the BFM-ALL. NHL/86 protocol for B-non-Hodgin's Lymphoma (NHL) and B-Acute Lymphoblastic Leukemia (B-ALL) in Argentina. Design. Prospective, single arm, non-randomized trial. PATIENTS AND METHODS: From August 1988 to December 1993, 87 consecutive patients with B-NHL/B-ALL were admitted and 82 were eligible. The therapy was stratified according to stage. All patients received a cytoreductive prephase with cyclophosphamide and prednisone. Those with stage I-II were treated with three 5-day blocks of combined intense chemotherapy including dexamethasone, cyclophosphamidie, ifosfamide, cytarabine, teniposide, doxorabicin, and 500 mg/m2 of methotrexate as a 24 hour continuous infusion. Stage III received 6 blocks and those with stage IV/B-ALL received 6 intensified blocks in which 2 g/m2 of 24 hour continuous infusion methotrexate and vincristine were added. Triple intrathecal therapy was given for CNS prevention. After the first two blocks the response was assessed and those with a partial response were offered optionallya second look surgery or local radiotherapy. RESULTS: With a median follow-up of 38 (range 16-71) months, the event-free survival (pEFS) for the whole group was 0.69 (Stage I-II n = 16 pEFS = 0.94, stage III n = 50 pEFS = 0.66, Stage IV n = 7 pEFS = 0.43, B-ALL n = 9 pEFS = 0.66). Patients with stage III abdominal tumors who achieved a partial response by imaging studies after induction had a significantly higher risk of relapse than those with a complete response (p = 0.02). Relapse was the most frequent event Toxicity was mainly hematological. CONCLUSIONS: The application of this protocol was feasible in our setting and its results comparable to the German study. Patients with stage I-II had an excellent outcome. Those with stage III and B-ALL achieved an encouraging event-free survival, however those with abdominal tumors and partial response to induction chemotherapy fared less favourably. This strategy was less effective for patients with initial CNS disease.

Adolescent↗
PubMed1997

Hodgkin disease in children: results of a prospective randomized trial in a single institution in Argentina.

PURPOSE: To compare prospective treatment strategies in childhood Hodgkin disease to the following subsets of patients: a) Favorable prognostic group: these patients were randomized to receive 6 vs. 3 CVPP chemotherapy cycles without radiotherapy (CVPP: cyclophosphamide, vinblastine, procarbazine, and prednisone. The scheme was repeated every 28 days). b) Intermediate prognostic group: these patients were randomized to receive 6 cycles of CVPP or AOPE (AOPE: Adriamycin, vincristine, prednisone, and etoposide). Between the third and fourth cycles, all patients in this group received radiotherapy (RT)(30-40 Gy to initially involved areas). c) Unfavorable prognostic group: those patients received a single arm regimen of 6 cycles of CCOPP/CAPTe (3 of each combination) every 28 days. All these patients received radiotherapy (30-40 Gy to initially involved areas). RESULTS: From October 1987 to December 1994, a total of 114 children and adolescents were evaluated. Mean age was 9 (range 2-17) years. There were 72 boys and 42 girls. With a median follow-up of 5 (range 1.5-8.7) years, at 80 months event-free survival (EFS) and overall survival (OS) for the whole cohort are 0.809 (SE: 0.04) and 0.873 (SE: 0.04), respectively (SE: Standard Error). Favorable prognostic group (n = 26) EFS is 0.831 (0.09) (Arm CVPP x 3:0.857 (0.13) and Arm CVPP x 6: 0.875 (0.08); p = non significant). Intermediate prognostic group (n = 64) EFS is 0.806 (0.05) (Arm CVPP x 6 + RT: 0.872 (0.05) and Arm AOPE x 6 + RT: 0.667 (0.10); p = 0.04). Unfavorable group (n = 24) EFS is 0.829 (0.07). CONCLUSIONS: Results of treatment for the whole group are satisfactory. However, 3 cycles of CVPP without radiotherapy obtain equal EFS than 6 cycles without radiotherapy in the favorable prognostic group. In the intermediate prognostic group, 6 cycles of CVPP plus radiotherapy obtain a superior EFS than 6 cycles of AOPE plus radiotherapy. With the success of treatment for Hodgkin disease in children, future research needs to be focused in reducing toxicity without altering the excellent actual outcome.

Adolescent↗
PubMed1997

Temporal regulation of growth cone lamellar protrusion and the influence of target tissue.

Guided nerve fiber growth depends upon the activities of the neuronal growth cone lamellae and filopodia. Defining the dynamics of growth cone remodeling and the influences that act on it may lead to greater understanding of guided axonal growth. While there were differences in the remodeling of growth cones of nerve fibers extended from spinal cord explants and from dorsal root ganglia of Rana pipiens larvae, both types exhibited fluctuations in lamellar expanse over time to produce "lamellar cycles." We now show that these cycles are characterized by the temporal regulation of lamellar protrusion rate, the percentage of the lamellar perimeter undergoing protrusion, and invariant lamellar retraction with respect to time. Since axotomies did not abolish the lamellar cycles, the mechanism underlying cycling appears to reside at the level of the nerve fiber terminus. The previously demonstrated effects of the target tissue on growth cone remodeling appear to be due to target tissue-released factors that bind to the culture substratum, as evidenced by experiments using target tissue-conditioned medium. Further, the target tissue attenuated the fluctuations in lamellar protrusion rate during cycling, which resulted in changes in growth cone remodeling and morphology. These alterations may be related to the chemokinetic and chemotropic effects of the target on the nerve fiber extension. Thus, the process of remodeling of growth cone lamellar structures is the result of intrinsically controlled modifications in lamellar protrusion and target-based influences.

Analysis of Variance↗
PubMed1997

Effects of epidermal growth factor on isolated digestive gland cells from mussels.

Effects of epidermal growth factor (EGF) and possible mechanisms of EGF-mediated signal transduction were investigated in isolated cells of the digestive gland of the mussel (Mytilus galloprovincialis Lam. ). EGF induced a cytosolic Ca2+ transient and subsequently stimulated DNA synthesis; both effects were dose-dependent in the nanomolar range and inhibited by pretreatment with an inhibitor of tyrosine kinase activity, suggesting specific EGFR-like receptors. The EGF-induced cytosolic Ca2+ transient was mainly due to a Ca2+ influx through the plasma membrane, possibly involving voltage-insensitive Ca2+ channels. Such a Ca2+ response was abolished by pretreatment with indomethacin and NDGA, inhibitors of arachidonic acid metabolism; similarly, the EGF-stimulated increase in DNA synthesis was significantly reduced. Indomethacin, a cyclooxygenase inhibitor, had the greatest effect on both EGF-induced responses. Results suggest the presence of EGF-responsive cells in the mussel digestive gland. A possible role for arachidonic acid and its metabolites in mediating the effects of EGF is also indicated.

Animals↗
PubMed1997

Incidence of and risk factors for hepatitis A in Italy: public health indications from a 10-year surveillance. SEIEVA Collaborating Group.

BACKGROUND/AIMS: This study aimed to evaluate the incidence of and risk factors for acute viral hepatitis A (HAV) in Italy. METHODS: Data were from a surveillance system for type-specific acute viral hepatitis (SEIEVA). To estimate the association of hepatitis A cases with the potential risk factors (Odds Ratios) and the proportion of all hepatitis A cases attributable to a given risk factor (population attributable risk), hepatitis B cases were used as controls. Independent predictors of HAV were estimated by conditional multiple logistic regression. RESULTS: During the period 1985-1994, 25553 viral hepatitis cases were reported. Of these, 6408 (25%) were due to hepatitis A (HAV). HAV incidence declined from 10/100000 in 1985 to 2/100000 in 1987. Since 1991, however, an increase in HAV has been observed. The majority of cases were 15-24 years old; the incidence was higher in males and in subjects residing in southern Italy. Only one death (0.02%) was observed. Shellfish consumption was the most frequently reported risk factor (62%). The proportion of cases reporting personal contact with an icteric case, travel to a high-medium endemic areas, and family contact with a child attending a day-care centre (household of day-care child) was 17%, 19% and 15%, respectively. The results of multivariate analysis showed that shellfish consumption (OR=2.6; 95% CI=2.4-2.9), travel to endemic areas for people residing in northern and central Italy (OR=5.4; 95% CI=4.6-6.2) and household of day-care child (OR=1.2; 95% CI=1.03-1.4), were all types of exposure independently associated with HAV. The estimates of population-attributable risk show that shellfish consumption explained as many as 42.2%, travel to high-medium endemic areas for people residing in northern and central Italy 24.2%, and household of day-care child only 1.4% of all acute hepatitis A cases in Italy. CONCLUSIONS: These findings indicate that HAV in Italy is mainly a food-borne disease. Vaccination against hepatitis A is strongly recommended for travellers to endemic areas.

Adolescent↗
PubMed1997

Immune complex glomerulonephritis in patients coinfected with human immunodeficiency virus and hepatitis C virus.

Human immunodeficiency virus-associated nephropathy (HIVAN), characterized by heavy proteinuria, rapidly progressive renal failure, "collapsing" glomerulopathy, and tubulointerstitial abnormalities, is the most common finding in HIV-infected patients undergoing a renal biopsy and predominantly affects blacks. We describe the clinical features and renal pathologic findings of 12 intravenous drug users (IVDUs) coinfected with HIV and hepatitis C virus (HCV) who were selected for renal biopsy because they presented with features different from typical HIVAN, including hypertension, microscopic hematuria, and cryoglobulinemia. There were seven black and five Hispanic patients. Eleven patients had immune complex glomerulonephritis (ICGN); one had glomerulosclerosis with immune complex deposits. Ten individuals had evidence of past hepatitis B viral infection, but none had persistent hepatitis B surface antigenemia. No other underlying cause for immune complex glomerulonephritis was identified. Renal biopsy showed membranoproliferative glomerulonephritis in five patients, mesangial proliferative glomerulonephritis in five, membranous nephropathy in one, and "collapsing" glomerulopathy with immune complex deposits in one. Hepatitis C virus RNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) in the renal tissue and/or serum of nine of the 11 patients tested, and also in the renal biopsy tissue of four of eight patients with clinical and pathologic features of typical HIVAN without immunofluorescence evidence of immune complex deposits. One patient presented with renal failure, five patients developed end-stage renal disease (ESRD) requiring hemodialysis (mean time, 6.5 months), and six had stable renal function after a mean follow-up of 29.1 months (range, 2 to 72 months). Liver function abnormalities were present in seven of the 12 individuals, including four of the six patients who developed renal failure. These findings indicate that in some patients coinfected with HIV and HCV, the development of ICGN may dominate the clinical course of the disease. The occurrence of ICGN among black patients at risk for HIVAN may be related to the relatively high prevalence of HCV infection among IVDUs in this group.

AIDS-Associated Nephropathy↗
PubMed1997

Amino-terminal identity of co-existent amyloid and non-amyloid immunoglobulin kappa light chain deposits. A human disease to study alterations of protein conformation.

Tissue deposition of monoclonal immunoglobulin light chains is a serious complication in some patients with B cell proliferative disorders. The deposits are typically fibrillar and Congophilic in amyloid (AL) and non-fibrillar and Congophobic in light chain deposition disease (LCDD), and rarely coexist in the same patient. From post-mortem tissue of an individual with fibrillar and non-fibrillar kappa light chain deposits in different sites, we separately extracted and analysed biochemically and immunochemically the non-amyloid deposits from isolated glomeruli, the amyloid from isolated renal arteries and the amyloid from myocardium in which the only deposits were amyloid restricted to mural arteries. Western blotting analysis of both the extracted amyloid and the non-amyloid deposits demonstrated 25-kD bands immunoreactive with anti-kappa antibody, and the identity of the N-terminal amino acid sequences that belong to the variable region kappaIV light chain subgroup. This is the first human disease in which antigenically similar but morphologically different deposits have been separately biochemically analysed. We propose that combined LCDD and AL is an ideal human disease to study the relationships and the factors that influence the conversion of non-amyloidogenic to amyloidogenic conformations.

Aged↗