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L Weiss

Publications and source records attributed to L Weiss.

At least 163 records · Page 9Linked to original sources
PubMed1994

Epigenetic lesions at the H19 locus in Wilms' tumour patients.

To test the potential role of H19 as a tumour suppressor gene we have examined its expression and DNA methylation in Wilms' tumours (WTs). In most WTs (18/25), H19 RNA was reduced at least 20-fold from fetal kidney levels. Of the expression-negative tumours ten retained 11p15.5 heterozygosity: in nine of these, H19 DNA was biallelically hypermethylated and in two cases hypermethylation locally restricted to H19 sequences was also present in the non-neoplastic kidney parenchyma. IGF2 mRNA was expressed in most but not all WTs and expression patterns were consistent with IGF2/H19 enhancer competition without obligate inverse coupling. These observations implicate genetic and epigenetic inactivation of H19 in Wilms' tumorigenesis.

Alleles↗
PubMed1994

Hypocomplementaemia of poststreptococcal acute glomerulonephritis is associated with C3 nephritic factor (C3NeF) IgG autoantibody activity.

We have observed that decreased plasma levels of C3 in the serum of three children with poststreptococcal acute glomerulonephritis (PSAGN) at the time of presentation were associated with the presence of C3NeF activity in purified serum IgG from the patients. C3NeF activity was determined using a sensitive assay measuring the ability of patients' IgG to stabilize a preformed cell-bound alternative pathway convertase complex. C3NeF activity of patients' IgG decreased within weeks as plasma levels of C3 progressively returned to normal values. C3NeF activity became undetectable within 1-4 months following normalization of plasma C3 levels. Our observations suggest that early alternative pathway-dependent hypocomplementaemia, a cardinal feature of PSAGN, is mediated by the transient expression of C3NeF autoantibody activity by patients' IgG.

Acute Disease↗
PubMed1994

Lipoprotein abnormalities without hyperlipidaemia in moderate renal insufficiency.

To characterize lipoprotein metabolism during early renal insufficiency, plasma lipid and apolipoprotein profiles were determined in normotriglyceridaemic (NTG, n = 31) and hypertriglyceridaemic (HTG, n = 30) middle-aged patients with primary renal disease and with moderately impaired renal function (GFR 20-55 ml/min, mean: 37.2). Mean GFR was similar in the two patient groups. They were compared with 102 normolipidaemic control subjects. In comparison with controls the NTG patients (plasma triglycerides TG < or = 1.7 mmol/l, mean TG: 1.16 mmol/l) had significantly increased plasma concentrations of apo C-III and apoB. The apoA-I levels tended to be lower and as a consequence the apoA-I/apoC-III ratio, considered to represent the hallmark of the altered apolipoprotein profile in renal dyslipoproteinaemia, was markedly lower in NTG patients (8.7 versus 16.8, P < 0.001). There was also a reduction of the antiatherogenic ratio apoA-I/apoB and an increase of the apoC-III/apoE ratio. The HTG patients (mean TG: 3.22 mmol/l) showed the same, but even more accentuated, qualitative changes as the NTG patients. There was a fourfold increase of apoC-III in VLDL-LDL lipoprotein fractions with little change in HDL in the HTG patients. In NTG patients the increase of apoC-III was found in VLDL-LDL and in HDL. Plasma insulin and PTH levels both correlated with the apoA-I/apoC-III ratio independently of GFR and BMI. This suggests a pathogenetic relationship between PTH-mediated alterations of insulin metabolism and the lipoprotein abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoproteins↗
PubMed1994

Selective disappearance of C3NeF IgG autoantibody in the plasma of a patient with membranoproliferative glomerulonephritis following renal transplantation.

The serum of patients with membranoproliferative glomerulonephritis (MPGN) often exhibits C3 nephritic factor activity (C3NeF) associated with autoantibodies directed against the C3bBb alternative complement pathway C3 convertase. In the present study, we have sequentially assessed C3NeF activity in the purified IgG fraction of the serum of a patient with MPGN type II and end-stage renal disease every month for 1 year following renal transplantation and bilateral nephrectomy. C3NeF activity in the patient's purified serum IgG decreased with time from the first month after transplantation and became undetectable after forty-five weeks. At that time, plasma levels of C3 and factor B had returned to normal values. The disappearance of C3NeF activity in patient's IgG was selective in that no change in activity of two other autoantibodies and of one antibody against a non-self antigen was observed with time, indicating that the decrease in C3NeF activity was not related to a non-specific effect of immunosuppressive therapy. Loss of C3NeF activity was not related to the generation of anti-idiotypic antibodies against C3NeF. This study documents for the first time the selective disappearance of C3NeF activity following renal transplantation and bilateral nephrectomy. The results suggest that the autoantibody represents an antigen-driven expansion of self reactive B cell clones in response to a specific disease process in the kidney of patients with MPGN.

Adult↗
PubMed1994

Molecular characterization of de novo secondary trisomy 13.

Unbalanced Robertsonian translocations are a significant cause of mental retardation and fetal wastage. The majority of homologous rearrangements of chromosome 21 in Down syndrome have been shown to be isochromosomes. Aside from chromosome 21, very little is known about other acrocentric homologous rearrangements. In this study, four cases of de novo secondary trisomy 13 are presented. FISH using alpha-satellite sequences, rDNA, and a pTRI-6 satellite I sequence specific to the short arm of chromosome 13 showed all four rearrangements to be dicentric and apparently devoid of ribosomal genes. Three of four rearrangements retained the pTRI-6 satellite I sequence. Case 1 was the exception, showing a deletion of this sequence in the rearrangement, although both parental chromosomes 13 had strong positive hybridization signals. Eleven microsatellite markers from chromosome 13 were also used to characterize the rearrangements. Of the four possible outcomes, one maternal Robertsonian translocation, two paternal isochromosomes, and one maternal isochromosome were observed. A double recombination was observed in the maternally derived rob(13q13q). No recombination events were detected in any isochromosome. The parental origins and molecular chromosomal structure of these cases are compared with previous studies of de novo acrocentric rearrangements.

Chromosomes, Human, Pair 13↗
PubMed1994

Successful purging of murine plasmacytoma by mafosfamide (ASTA-Z).

Mafosfamide (ASTA-Z) is a chemotherapeutic agent currently in use for in vitro purging of tumor-bearing human BM cells prior to autologous bone marrow transplantation (ABMT). We tested the efficacy of ASTA-Z against mouse plasmacytoma cells MOPC-315 (MOPC), a model of human multiple myeloma. BALB/c mice were injected intraperitoneally with different doses of MOPC preincubated with ASTA-Z. All control mice receiving > or = 10(4) MOPC intraperitoneally (ip) died within 23 days. All recipients of ASTA-Z pretreated MOPC remained healthy for > 180 days. To simulate the clinical situation, BALB/c mice received lethal doses of 10(3) MOPC ip prior to ABMT. Subsequently, mice were treated with cyclophosphamide 200 mg/kg one day prior to syngeneic BMT with 10(7) BMC containing 10(6) MOPC; 90% of the mice receiving unpurged syngeneic BMC died within 45 days whereas all mice transplanted with ASTA-Z-treated BMC/MOPC mixtures remained disease-free for > 100 days. Our results suggest that a similar approach may be successful in patients with multiple myeloma and residual disease prior to cryopreservation of their BM for ABMT. Bone marrow purging with ASTA-Z is effective and under certain conditions could be critical for prevention of relapse following ABMT, provided that effective elimination of residual disease in the host can be achieved by the conditioning regimen prior to ABMT.

Animals↗
PubMed1994

[Exploration of the complement system in clinical practice].

The complement system plays an important role in defence of the host against infection and in the clearance of immune complexes. Defects in complement proteins are often associated with infections or auto-immune/immune complex diseases. Investigation of complement is useful for diagnosis and following of autoimmune diseases. Hypocomplementemia may result from genetic deficiency and/or consumption through activation of the system. In the particular case of angioneurotic oedema, laboratory data are essential to confirm the diagnosis and to the follow-up of the patients. Inappropriate activation of the complement system associated with the release of inflammatory mediators contributes to the tissue damage.

Child↗
PubMed1994

Effect of total lymphoid irradiation on natural killer cells and cytotoxic and primed T lymphocytes.

Total lymphoid irradiation (TLI), which results in prolonged depression of the number and function of T and B cells, augments the natural killer (NK) cell activity. Small doses of irradiation (200-400 cGy) in vitro did not reduce the lytic activity of TLI-induced NK cells, whereas irradiation with 1,500 and 3,000 cGy decreased NK function by 50-70%. Addition of TLI spleen cells, containing a high proportion of large mononuclear cells, to cytotoxic T lymphocytes (CTL), generated in vitro by one-way mixed lymphocyte reaction and tested against 51Cr labeled target cells, suppressed the lytic activity 27-57% of that observed following the addition of normal spleen cells. The suppressive effect induced by spleen cells of TLI-treated mice was H2 nonrestrictive. Primed T lymphocytes (PTL) stimulated with irradiated allogeneic cells were inhibited by cocultured TLI spleen cells, causing inhibition of 57% as measured by secondary proliferative response and 86% inhibition by primary response to a third strain of cells. Our results, together with previously published data, indicate that TLI-induced suppressor cells inhibit the generation of PTL and CTL. Secondary proliferative responses of T cells primed to alloantigens are suppressed, as is the lysis of target cells by CTL. All suppressive phenomena presented here are antigen nonspecific.

Animals↗
PubMed1994

The hepatitis B virus preS2/St transactivator utilizes AP-1 and other transcription factors for transactivation.

Integrated hepatitis B virus DNA cloned from hepatitis B virus-associated hepatocellular carcinoma frequently contains 3'-truncated middle surface genes (preS2/St), which were recently found to have a transcriptional transactivator function. Because preS2/St, among others, is able to transactivate the promoters of the cellular oncogenes c-myc and c-fos, it has been speculated that integrated preS2/St genes might contribute to hepatitis B virus-associated liver carcinogenesis. In this study, we investigated the mechanism of target gene stimulation by preS2/St. It was found that deletion of a fragment containing the binding site for transcription factor AP-1 (Jun-Fos) substantially decreases inducibility of the human c-myc promoter by preS2/St. A subsequent investigation of AP-1 activation by preS2/St revealed the following: (a) insertion of multimeric AP-1 binding sites confers inducibility to an otherwise unstimulatable test promoter; (b) transactivation of AP-1 sites is dramatically increased when Jun and Fos are overexpressed by cotransfected expression plasmids; and (c) inhibitors of AP-1 activation also impair transactivation by preS2/St. Besides AP-1, preS2/St was also able to utilize the unrelated transcription factors NF-kappa B and AP-2 for transactivation, suggesting that the gene product of preS2/St acts indirectly through one or several general cellular pathways rather than as a bona fide transcription factor. Because AP-1 conveys induction of a large panel of tumor-relevant genes, its preS2/St-dependent activation implies a possible causative role in hepatitis B virus-associated hepatocarcinogenesis.

Animals↗
PubMed1993

Deficient transcription of XIST from tiny ring X chromosomes in females with severe phenotypes.

The severe phenotype of human females whose karyotype includes tiny ring X chromosomes has been attributed to the inability of the small ring X chromosome to inactivate. The XIST locus is expressed only from the inactive X chromosome, resides at the putative X inactivation center, and is considered a prime player in the initiation of mammalian X dosage compensation. Using PCR, Southern blot analysis, and in situ hybridization, we have looked for the presence of the XIST locus in tiny ring X chromosomes from eight females who have multiple congenital malformations and severe mental retardation. Our studies reveal heterogeneity within this group; some rings lack the XIST locus, while others have sequences homologous to probes for XIST. However, in the latter, the locus is either not expressed or negligibly expressed, based on reverse transcription-PCR analysis. Therefore, what these tiny ring chromosomes have in common is a level of XIST transcription comparable to an active X. As XIST transcription is an indicator of X chromosome inactivity, the absence of XIST transcription strongly suggests that tiny ring X chromosomes in females with severe phenotypes are mutants in the X chromosome inactivation pathway and that the inability of these rings to inactivate is responsible for the severe phenotypes.

Adolescent↗
PubMed1993

Inhibition of metastatic cell colonization in murine lungs and tumor-induced morbidity by non-peptidic Arg-Gly-Asp mimetics.

The spreading and colonization of tumor cells require their migration to metastatic sites via blood vessels. To penetrate blood-vessel walls, cells, including malignant ones, must recognize and associate with the sub-endothelium extracellular matrix (ECM) and its glycoproteins. Recognition of ECM-glycoproteins, such as fibronectin (FN) and vitronectin (VN), is mediated by integrin receptors expressed on various cell types, including platelets, leukocytes and tumor cells. The Arg-Gly-Asp (RGD)-containing peptide, a major adhesive ligand of ECM, is present in various plasma and matrix glycoproteins, such as FN and VN. Non-peptidic mimetics of RGD, consisting of carboxylate and guanidinium groups of Asp and Arg divided by a linear atom spacer, express a high affinity for the alpha IIb-beta 3 integrin and inhibit platelet aggregation. Herein, the ability of RGD mimetics to inhibit adhesive interactions between tumor cells and RGD, and tumor progression in vivo, was examined. RGD-containing peptides and the RGD mimetic, compound SF-6,5, but not the Arg-Gly-Glu (RGE) peptide or the corresponding mimetic, specifically inhibited B16-F10 melanoma cell adhesion to immobilized VN and FN. Daily administration in vivo of SF-6,5 to mice inhibited the formation of B16-F10 colonies in experimental and spontaneous models of metastases. Moreover, SF-6,5 could prevent mouse death caused by massive colonization of tumor cells in the lungs. The therapeutic effect of RGD-containing peptides on tumor metastasis formation was marginal, probably due to the small amounts used, and its susceptibility to proteolysis in situ. Thus, non-peptidic mimetics of small adhesive epitopes may provide a novel therapeutic tool to prevent an adverse pathological event involving integrin-dependent cell-cell and cell-ECM interactions.

Animals↗
PubMed1993

Spontaneous and IL-2-induced anti-leukemic and anti-host effects against tumor- and host-specific alloantigens.

The graft-vs-leukemia (GVL) effect and its connection to graft-vs-host disease (GVHD) were studied in F1 hybrid mice after parental bone marrow transplantation. (BALB/c x C57BL/6) F1 mice (F1) were sublethally and lethally irradiated and inoculated with 10(4) BCL1 cells, a murine leukemia of BALB/c (BALB) origin. Subsequently mice were transplanted with F1 (syngeneic), BALB (allogeneic to the host but syngeneic to the tumor), C57BL/6 (B6) (allogeneic to both host and tumor) spleen cells, or spleen cells mixed with syngeneic (F1) bone marrow cells, respectively. Fresh BALB (H-2d) and B6 (H-2b) spleen cells, which induce equally strong GVHD in the F1 recipient against H-2b and H-2d alloantigens, respectively, were assayed for their ability to induce GVL effects on BCL1 (H-2d) cells with and without in vivo administration of human rIL-2. In order to increase the GVL effects, spleen cells were incubated for 4 days with rIL-2 to generate IL-2-activated killer cells. The results of adoptive transfer experiments showed that only immunocompetent B6 cells led to consistent eradication of leukemia. Neither BALB nor syngeneic F1 cells induced curative GVL effects regardless of whether spleen cells were further stimulated with rIL-2 in vitro, in vivo, or both. Our data support the theory that GVL effects are caused by T cell-dependent immune responses of allogeneic T cells and not by MHC-nonrestricted NK or rIL-2-activated NK cells, independently of the GVHD process itself. Hence, recognition and killing of tumor cells is most probably a MHC-restricted T cell-dependent process.

Animals↗
PubMed1993

Inverted duplication of 8p: ten new patients and review of the literature.

We evaluated 10 patients with an inverted tandem duplication of 8p. Inverted duplications of chromosome 8 have been reported infrequently, and no syndrome has been previously identified. All 8 patients on whom birth histories were available were hypotonic at birth, and had feeding difficulties in the neonatal period. All patients have significant developmental delay. Manifestations present in 5 or more patients were prominent forehead, high arched palate, large mouth with a thin upper lip, malformed and/or apparently low-set ears, broad nasal bridge, dental and skeletal abnormalities, and joint laxity or hyperextensibility. Variation in the phenotype may, in part, be explained by the different breakpoints. Recurrence risks of de novo rearrangements are probably very low, but for the recombinants the risk may be significant. The duplication appeared to be de novo in 6 patients (both parental karyotypes were normal); maternal karyotypes were normal in 2 patients, and both parents of 1 patient were not available. One propositus had a monocentric recombinant of a paracentric inv(8) (p12p23.3) carried by the mother, and is one of only 6 known cases of duplication associated with a balanced paracentric inversion in a parent. The carrier parent was the mother in 5 of those 6 cases. Each case involved a different chromosome, and each probably was created by an unusual meiotic recombination event. Inverted duplication 8p is one of the most common duplications observed in our laboratories, and ranks in frequency with the classical deletions, such as Wolf-Hirschhorn and cri-du-chat syndromes and duplication or secondary trisomy 15q1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

X-inactivation pattern in an Ullrich-Turner syndrome patient with a small ring X and normal intelligence.

In a description of 8 girls who had Ullrich-Turner syndrome (UTS) with a small r(X), mental retardation, and other unusual findings, it was hypothesized that the distinctive phenotype was associated with the loss of the X inactivation center from the r(X) and lack of genetic inactivation of the ring [Van Dyke et al., 1992]. Here, we present a 17-year-old young woman with 45,X/46,X,r(X)(?p11q13) mosaicism, Ullrich-Turner syndrome, and normal intelligence. In situ hybridization with the X-centromere DNA probe DXZ1 (Oncor, Inc., Gaithersburg, MD) was performed on previously G-banded slides, and the probe hybridized to the centromere regions of the normal X and the ring. The r(X) appears to be inactivated since a buccal smear demonstrated 5% Barr bodies. Furthermore, DAPI stain and FISH analysis with the X-centromere DNA probe DXZ1 was employed to distinguish the inactive X from the active X, and verified the presence of a sex chromatin mass in fibroblasts. These observations are consistent with the active-ring-X-and-mental-retardation hypothesis since the ring in this patient, although very small, appears to be normally inactivated and she has normal intelligence.

Adolescent↗
PubMed1993

Cancer-cell traffic in the liver. III Lethal deformation of B16 melanoma cells in liver sinusoids.

It has previously been shown that most of the B16F10 melanoma cells delivered to the mouse liver via the portal vein are rapidly killed in periportal zone 1 of the sinusoids. Few intact viable cells reach pericentral zone 3 of the sinusoids and of these, only a very small proportion leave the liver to colonize the lungs. The hypothesis has been advanced that one non-exclusive, potential mechanism for cancer-cell destruction in the liver is a result of the deformation of cancer cells when they enter vessels of smaller diameter than themselves. Where entry is associated with change in shape from spheroid to cylindrical, a mandatory increase in cancer-cell surface area occurs, which is first apparent and utilizes surface membrane excess (rugosity). If this increase is insufficient, a real increase occurs which, if in excess of approximately 4%, results in lethal surface membrane rupture. This hypothesis predicts that, under these circumstances, cancer-cell resistance to mechanical trauma is favored by small diameter and utilizable surface membrane excess. To test this hypothesis, the traffic of melanoma cells in the liver following portal-vein injection has been observed by confocal microscopy and image reconstruction. In accordance with the hypothesis, non-disrupted cells within the sinusoids have a smaller mean diameter than that of the original inoculum, and show evidence of utilization of surface membrane excess. The results indicate that deformation-associated trauma, suffered by cancer cells on entry and residence in the microvasculature, may well be an important factor contributing to metastatic inefficiency.

Animals↗
PubMed1993

Weekly cisplatin and radical radiation therapy for advanced, recurrent, and poor prognosis cervical carcinoma.

BACKGROUND: A Phase I-II trial of cisplatin and radical radiation therapy was initiated for advanced, recurrent, and poor prognosis carcinoma of the uterine cervix. METHODS: From September 1983 to October 1991, 55 patients were entered on the protocol. Forty patients had advanced cervical carcinoma International Federation of Gynecology and Obstetrics (FIGO) Stages IIB-IVB, 4 patients were treated for recurrent disease, and 11 patients had FIGO Stage I disease with poor prognostic factors. Cisplatin was administered weekly on an outpatient basis at a dose of 1 mg/kg (maximum, 60 mg) during teletherapy. The radiation fields included the pelvis only in 20 patients, the pelvis and paraaortic fields in 33 patients, and the paraaortic fields alone in 2 patients. The total number of cycles of cisplatin received ranged from 3-6 (mean 5.2). There were no interruptions in the planned radiation therapy. RESULTS: Neutropenia occurred in 18 of 55 patients (32.7%) with only 1 (1.8%) having Grade IV toxicity. Mild thrombocytopenia occurred in only one patient. No significant gastrointestinal, neurologic, or renal toxicity was observed. Of the 48 patients with measurable or evaluable disease, all had a complete response within the radiation field. The follow-up has ranged from 1-85+ months. Currently, there have been 19 (34.5%) recurrences, only 2 (3.7%) of which have occurred in the radiation field. CONCLUSIONS: The weekly cisplatin chemotherapy administered during radiation therapy was well tolerated in this high-risk group of patients and did not diminish the ability to give standard doses of radiation.

Adenocarcinoma↗
PubMed1993

Interstitial deletion of chromosome 10, del(10) (q11.2q22.1) in a boy with developmental delay and multiple congenital anomalies.

We describe a 4-year-old boy with an interstitial deletion of the long arm of chromosome 10: del(10) (q11.2q22.1). Frontal bossing, hypertelorism, bright blue iris color, up-slanting palpebral fissures, a flat nasal bridge, a broad nose, apparently low-set ears, micrognathia, deep philtrum, and hypotonia were noted neonatally. A murmur was noted at age 5 1/2 months and surgical repair of subaortic stenosis was required at 4 years. At 4 years micrognathia was no longer evident, but the palate was high-arched. The pattern of abnormalities included postnatal-onset slow growth, short stature, mental retardation, and cardiac anomalies.

Abnormalities, Multiple↗