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Biomedical subjects

M Shaklai

Publications and source records attributed to M Shaklai.

At least 37 records · Page 2Linked to original sources
PubMed1998

Collagen binding induces changes in its platelet integrin receptor alpha2beta1.

Integrins can signal upon binding of their ligand, presumably because of conformational changes induced by ligand-binding. It has been postulated that ligand binding causes changes in the affinity of the integrin to its ligand. In order to test for ligand-induced change in the affinity of platelet alpha2beta1 to collagen, labelled viable platelets were passaged through a column of fibrillar collagen and stringent lysis conditions were used to remove all low-affinity receptors. A high-affinity fraction left on the collagen could be eluted with dithiothreitol (DTT) and 2% Sodium dodecyl sulfate (SDS). Antibodies raised against this fraction, identified alpha2beta1 by Western-blotting. Functional tests performed with the antibodies confirmed the involvement of the high-affinity proteins in platelet-collagen interactions attributed to alpha2beta1: inhibition of collagen-specific platelet adhesion and aggregation. EDTA, chaotropic agents or low pH did not elute the high affinity fraction of alpha2beta1. However, DTT followed by acetic acid did, which indicates that the steps necessary to disrupt the high-affinity collagen alpha2beta1 bond are reduction of disulfide bond(s) followed by disruption of electrostatic interactions. Our data 2 1 suggest that (i) ligand binding induces the formation of a new disulfide bond in a fraction of alpha2beta1, (ii) that this bond is an intrareceptor, and (iii) that this change increases the affinity of the receptor to its ligand.

Journal Article↗
PubMed1997

BCR-ABL transcripts in bone marrow aspirates of Philadelphia-negative essential thrombocytopenia patients: clinical presentation.

One of the diagnostic criteria of essential thrombocythemia (ET) is the absence of the Philadelphia chromosome (Ph-neg). On the molecular level, Ph-neg ET patients may carry BCR-ABL transcript. The natural history of BCR-ABL positive Ph-neg ET patients is undetermined. We examined the BCR-ABL status by reverse transcriptase two-step nested polymerase chain reaction in bone marrow aspirates of 25 Ph-neg ET patients. We found 12 BCR-ABL positive and 13 BCR-ABL negative patients in the study group. The comparison showed that the two groups had similar clinical and laboratory characteristics, except for a significant increased patients' age and decreased polymorphonuclear cell count in the BCR-ABL positive group. During a median follow-up of 20 and 22.5 months for the BCR-ABL negative and positive groups, respectively, there was neither blastic transformation nor unrelated death in both groups. We conclude that it is important to look for BCR-ABL transcript in Ph-neg ET patients and to follow them closely to investigate the nature of this translocation in this group of patients.

Adult↗
PubMed1997

Affinity modulation in platelet alpha 2 beta 1 following ligand binding.

In order to test for ligand-induced change in the affinity of platelet alpha 2 beta 1 to collagen we passaged labeled viable platelets through a column of fibrillar collagen and used stringent lysis conditions to remove all low-affinity receptors. A high affinity fraction left on the collagen could be eluted with DTT and 2% SDS. Antibodies raised against it Western-blotted alpha 2 beta 1. Functional tests performed with the antibodies confirmed the involvement of the high affinity proteins in platelet-collagen interactions attributed to alpha 2 beta 1: inhibition of collagen-specific platelet adhesion and aggregation. EDTA, chaotropic agents or low pH did not elute the high affinity fraction of alpha 2 beta 1. However, DTT followed by acetic acid did. Our data suggest that 1) ligand binding induces the formation of a new disulfide bond in a fraction of alpha 2 beta 1, 2) that this bond is intrareceptor and 3) that this change increases the affinity of the receptor to its ligand.

Blood Platelets↗
PubMed1997

Levels of proteins C and S do not decline subsequent to first line chemotherapy in lymphoma patients.

Thromboembolic complications and decrease in protein C and S have been observed in patients while receiving combination chemotherapy for breast cancer. We investigated whether initial cytotoxic treatment of non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD) is also associated with changes in these anticoagulant parameters. For this purpose 25 patients with intermediate to high grade NHL and seven with HD, undergoing primary treatment with cytotoxic drugs were evaluated at three time-points: pre-therapy, mid-therapy and post-therapy. In contrast to the breast cancer patients, no significant changes in protein C, protein S and antithrombin III levels were observed in the NHL patients during the various stages of therapy. However in HD patients, the mean protein C values had a tendency to be higher at mid-therapy compared to pre-therapy and protein S levels had a tendency to be higher at mid-therapy compared to post-therapy. In lymphoma patients receiving primary cytotoxic treatment we did not find changes in anticoagulant parameters that can explain a chemotherapy-induced hypercoagulable state, as has been reported in breast cancer patients.

Adolescent↗
PubMed1997

Effect of the cytostatic butyric acid pro-drug, pivaloyloxymethyl butyrate, on the tumorigenicity of cancer cells.

Previously we have shown that pivaloyloxymethyl butyrate (AN-9), a pro-drug of butyric acid (BA), is a differentiation-inducing agent in a variety of cells. In this report, we demonstrate that AN-9 is a cytostatic but not cytotoxic agent in a myelomonocytic cell line (WEHI); thus, the cells were growth-arrested and differentiated. These late changes in the cells were preceded by changes in the expression of the early regulatory genes, c-myc and c-jun. Although initiation of all these events had already occurred after 1 h exposure to AN-9, the tumorigenicity of these cells tested in Balb/c mice was not affected. A marked reduction in the tumorigenicity of AN-9-treated cells was observed after 4 h of exposure. Exposure of the highly metastatic subclone of Lewis lung carcinoma (3LLD122) to AN-9 resulted in a very pronounced effect on the tumorigenicity of these cells tested in C57BL mice. Unlike WEHI cells, the tumorigenicity of 3LLD122 was almost completely diminished after 1 h of exposure. In both cell types a 10-fold higher concentration of BA did not affect the tumorigenicity of the cells as did AN-9.

Animals↗
PubMed1997

Butyric acid and pivaloyloxymethyl butyrate, AN-9, a novel butyric acid derivative, induce apoptosis in HL-60 cells.

A novel butyric acid derivative, pivaloyloxymethyl butyrate, AN-9, was previously shown to be a potent differentiating agent. AN-9 exerts a significant anticancer activity in vitro and in vivo. In all the activities examined, AN-9 was more potent than butyric acid. Here we show that AN-9 and butyric acid induce cell death by apoptosis. Exposure of HL-60 cells to butyric acid and AN-9 decreased cell numbers and induced cell differentiation and the appearance of typical apoptotic features. Induction of apoptosis and/or differentiation by AN-9 and butyric acid was dependent on the concentration and the time of exposure to the drugs. The advantage of AN-9 over butyric acid was further confirmed. Apoptosis induced by AN-9 occurred after a shorter exposure and at lower drug concentrations than that induced by butyric acid. Apoptosis by AN-9 was accompanied by reduction in Bcl-2 expression. Preincubation with antioxidants did not protect HL-60 cells from apoptosis induced by AN-9. HL-60 cells that were induced to differentiate by preincubation with retinoic acid or low AN-9 concentrations were more resistant to apoptosis, induced later by high concentrations of AN-9, than were undifferentiated cells.

Antineoplastic Agents↗
PubMed1996

Severe myelotoxicity of oral etoposide in heavily pretreated patients with non-Hodgkin's lymphoma or chronic lymphatic leukemia.

BACKGROUND: Promising results have been reported for patients with non-Hodgkin's lymphoma (NHL) receiving chronic oral etoposide. Due to the small number of patients reported, information regarding side effects is limited, and therefore warrants further evaluation. METHODS: Twenty eligible patients with NHL and chronic lymphatic leukemia (CLL), resistant to or relapsed after previous protocols of polychemotherapy were treated with oral etoposide at a dosage of 50 mg/m2/day for 21 days in a 28-day cycle. Response and toxicity were evaluated according to standard criteria. RESULTS: Total response was noted in 13 patients, complete response in 2 patients, and partial response in 11 patients. Two patients had stable disease and five patients had progression of disease during treatment. Seventy-five percent of patients experienced neutropenia below 1500/microL. Half acquired infection and required hospitalization. Fifty-five percent required blood transfusions. All patients needed course shortening and dosage reduction. CONCLUSIONS: Chronic daily administration of oral etoposide is effective in patients with NHL and CLL. In heavily pretreated patients, myelotoxicity is severe. Therefore, modification of the schedule plan is mandatory in this group of patients.

Adult↗
PubMed1996

Esterase inhibitors diminish the modulation of gene expression by butyric acid derivative, pivaloyloxymethyl butyrate (AN-9).

Pivaloyloxymethyl butyrate (AN-9) belongs to the family of acyloxyalkyl ester prodrugs of carboxylic acids which undergo intracellular hydrolysis to yield butyric acid (BA). We have previously shown that AN-9 and BA reduce the level of c-myc and enhance c-jun transcripts in HL-60 cells, and that the differentiation of these cells, induced by AN-9, is dependent on the presence of intracellular esterases. In this study we show that esterase inhibitors abolish the changes induced by AN-9 on c-myc and c-jun expression. In contrast, esterase inhibitors do not change the effects of BA on c-myc or c-jun. Interestingly, these inhibitors affect the modulation induced by both AN-9 and BA on the retinoblastoma tumor suppressor gene. These data suggest that AN-9 is indeed a prodrug of BA and that prior intracellular hydrolysis by esterases is material for AN-9 activity.

Aniline Compounds↗
PubMed1995

Myopathy, lactic acidosis, and sideroblastic anemia: a new syndrome.

We describe 2 sibs (brother and sister) with myopathy, sideroblastic anemia, lactic acidosis, mental retardation, microcephaly, high palate, high philtrum, distichiasis, and micrognathia. Very low levels of cytochromes a, b, and c were detected in the patients' muscle mitochondria. Deposition of iron within the mitochondria of bone marrow erythroblasts was observed on electron microscopy. Irregular and enlarged mitochondria with paracrystalline inclusions were also seen on electron microscopy of the patients' muscle specimen. Examination of DNA from the affected sibs showed no deletions in the mitochondrial DNA nor the mutations identified in the syndromes of mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) or myoclonus, and epilepsy associated with rugged-red fibers (MERRF). Since the parents were first cousins and 2 of 6 sibs (male and female) were affected, we suggest that the syndrome expressed by our patients represents a previously unknown autosomal recessive disorder that includes mitochondrial myopathy, lactic acidosis, and sideroblastic anemia.

5-Aminolevulinate Synthetase↗
PubMed1995

Interferon-alpha-2b with VMCP for induction in multiple myeloma: the Israel Myeloma Cooperative Group experience.

In 1988, a prospective, randomized multicenter study was initiated to determine the efficacy of a combined induction regimen with recombinant interferon-alpha-2b (IFN-alpha) and maintenance with IFN-alpha on the response and survival rates in multiple myeloma (MM) patients. Induction therapy consisted of VMCP (vincristine, melphalan, cyclophosphamide, prednisone), randomized to combine IFN-alpha at a dose of 2 x 10(6) U, 5 days per week throughout the induction period of 12 months. Patients who achieved plateau phase were subsequently randomized again between IFN alpha maintenance (2 x 10(6) U, 3 days a week) for 12 months and no maintenance therapy. Of the previously untreated patients, 84 were initially randomized for induction therapy, and 31 for the maintenance phase with IFN-alpha. Results of the cohort median survival, based on the intention to treat, have shown that those on the VMCP/IFN-alpha arm had a median survival of 53 months, compared with patients on the VMCP induction arm who a median survival of 26 months (P = 0.052). The median survival of stage 3 evaluable patients who were on the VMCP/IFN induction arm was 43 months, and 13 months for patients treated by VMCP alone (P = 0.008). No significant difference in survival was detected among patients in partial remission (after induction) who had a second IFN-alpha randomization at the plateau phase. Hematologic toxicity, mild to moderate fever, and fatigue were more common in the VMCP/IFN induction arm. The results show that VMCP/IFN is a well-tolerated treatment regimen, and is superior to VMCP for patients with stage 3 myeloma.

Adult↗
PubMed1994

Orbital and adnexal involvement in systemic non-Hodgkin's lymphoma.

BACKGROUND: The orbit is rarely a secondary site of lymphoma dissemination, and only few reports exist on the course and characteristics of involvement in these sites. METHODS: The authors retrospectively reviewed the records of 187 consecutive patients with systemic non-Hodgkin's lymphoma (NHL) diagnosed and treated at Beilinson Medical Center between 1986 and 1992. RESULTS: Ten patients (5.3% of those with NHL) had orbital or adnexal involvement or both. Histologically, six had intermediate-grade lymphoma, three had diffuse small cleaved cell lymphoma, and one had nodular small cleaved cell lymphoma. In all 10 patients, the lymphoma was widespread, and in 6, there were two or more other extranodal sites of involvement, mainly, bone marrow (six) and skin (three). The orbital involvement was found either at presentation or as late as 53 months after primary diagnosis. Various therapeutic approaches were chosen, from local orbital irradiation to different mild to aggressive chemotherapeutic protocols. Complete regression of the orbital or adnexal involvement or both was observed in 9 of 10 patients, but in 6 the systemic disease either persisted or recurred at other sites. CONCLUSIONS: Orbital or adnexal involvement or both by NHL may appear at any time during the course of the disease. It responds well to either chemotherapy or radiation therapy with prolonged local remission. The results of this study strongly suggest that every patient with NHL in whom any periorbital or orbital mass, ptosis, proptosis or lid edema develops should be suspected of having orbital lymphoma involvement until proven otherwise.

Aged↗
PubMed1994

Comparison between the effect of butyric acid and its prodrug pivaloyloxymethylbutyrate on histones hyperacetylation in an HL-60 leukemic cell line.

A butyric acid pro-drug, pivaloyloxymethyl butyrate, AN-9, developed in our laboratory, was previously shown to act as a differentiation-inducing and an anti-cancer agent. In this study we have shown that both AN-9 and butyric acid caused a transient hyperacetylation of histones, which returned to basal levels after 6 and 12 hr, respectively. This activity precedes the induction of differentiation elicited by both agents. AN-9 induced acetylation of histones at a concentration one order of magnitude lower than butyric acid. Pre-treatment of the cells with esterase(s) inhibitors diminished the ability of AN-9 to inhibit proliferation and induce differentiation. The above suggests that the intracellular release of butyric acid fragment, from the pro-drug, is catalyzed by cellular esterase(s).

Acetylation↗
PubMed1993

Rapid alteration of c-myc and c-jun expression in leukemic cells induced to differentiate by a butyric acid prodrug.

The novel prodrug of butyric acid (BA), pivaloyloxymethyl butyrate, has been shown, in vitro, to induce differentiation and inhibit leukemic cell proliferation. The prodrug affects the cells in vitro at lower concentration and at least 100 times faster than does (BA). We have compared the ability of BA with that of its prodrug AN-9 to modulate the expression of the early regulating genes, c-myc and c-jun, in HL-60 cells. Exposure of HL-60 cells to the prodrug resulted in a decrease of c-myc and an increase of c-jun expression. The prodrug elicited this effect at lower concentrations and at least 100 times faster than BA. Since changes in the expression of c-myc and c-jun occur minutes after exposure of the cells to the prodrug, these genes are likely to play a major role in the early stages of the differentiation pathway.

Antineoplastic Agents↗
PubMed1993

[Relapse of multiple myeloma in extramedullary sites].

Multiple myeloma was diagnosed in a 69-year-old man with pathological hip fracture, who had increased plasma cells in the bone marrow, osteolytic lesions in bones, low level of monoclonal protein (IgAK) in serum and urine, and anemia, hypercalcemia and renal insufficiency. He was treated for 1 year with chemotherapy with good results. 6 months after cessation of treatment the disease relapsed with multiple extramedullary plasmacytomas in skin and subcutaneous areas, right eyebrow, right knee, sternum and right axilla, but repeated bone marrow examinations were without evidence of disease activity. Chemotherapy was resumed but the patient died 1.5 years after the relapse with severe jaundice due to multiple liver plasmacytomas and pelvic masses.

Aged↗
PubMed1993

Relapse of aggressive myeloma after complete remission in secondary acute leukemia: coincidence or consequence?

We describe a patient with multiple myeloma who developed secondary acute myelomonocytic leukemia after long-term melphalan treatment. Following two courses of low-dose cytarabine, complete remission of the A.M.L. was achieved. Shortly thereafter an aggressive relapse of the quiescent myeloma occurred with acute renal failure and massive infiltration of bone marrow with multinucleated giant plasma cells. Although it is well known that administration of melphalan to patients with multiple myeloma increases the likelihood of A.M.L., this case demonstrates that treatment of A.M.L. in a patient with multiple myeloma may perhaps influence the course of multiple myeloma.

Antigens, CD↗
PubMed1992

Novel anticancer prodrugs of butyric acid. 2.

The antitumor activity of novel prodrugs butyric acid was examined. The in vitro effect of the compounds on induction of cytodifferentiation and on inhibition of proliferation and clonogenicity showed that (pivaloyloxy)methyl butyrate (1a) (labeled AN-9) was the most active agent. SAR's suggested that its activity stemmed from hydrolytically released butyric acid. In vivo, 1a displayed antitumor activity in B16F0 melanoma primary cancer model, manifested by a significant increase in the life span of the treated animals. Murine lung tumor burden, induced by injection of the highly metastatic melanoma cells (B16F10.9), was decreased by 1a. It also displayed a significant therapeutic activity against spontaneous metastases which were induced by 3LL Lewis lung carcinoma cells. Moreover, 1a has the advantage of low toxicity, with an acute LD50 = 1.36 +/- 0.1 g/kg (n = 5). These results suggest that 1a is a potential antineoplastic agent.

Animals↗