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Biomedical subjects

W H Miller

Publications and source records attributed to W H Miller.

At least 109 records · Page 6Linked to original sources
PubMed1994

Molecular diagnosis and monitoring of acute promyelocytic leukemia treated with retinoic acid.

The characteristic balanced 15;17 translocation, t(15;17), of acute promyelocytic leukemia (APL) fuses the retinoic acid receptor alpha (RAR alpha) gene on chromosome 17 to PML, a recently described gene of unknown function, on chromosome 15. It is this fusion gene and consequent fusion protein that is thought to be responsible for both the block in normal myelocyte differentiation as well as the dramatic in vitro and in vivo response to the differentiating effects of all-trans retinoic acid (RA). The t(15;17) also provides a genetic marker for the presence of leukemic cells. PML/RAR alpha fusion mRNA's can be detected by a reverse transcription polymerase chain reaction (RT-PCR) assay. Using this assay, at least three distinct patterns, differing in the 3' region of the PML breakpoint, can be identified. The detection of abnormal mRNA's by the RT-PCR assay has proven to be an important aid in the diagnosis of APL as well as the best predictor of an initial clinical response to RA. The results of an ongoing, longitudinal evaluation of patients with APL show that the RT-PCR assay may also be a useful indicator of minimal residual disease (MRD). Negative RT-PCR assays following completion of all therapy are associated with prolonged disease free survival, whereas persistence or return of a positive test is highly correlated with subsequent relapse. Further studies will determine whether patients who test positive may benefit from the introduction of additional antileukemic therapy.

Humans↗
PubMed1994

Treatment of acute promyelocytic leukemia with all-trans retinoic acid: an update of the New York experience.

In an ongoing study, we treated 79 patients with a molecular diagnosis of acute promyelocytic leukemia (APL) using all-trans retinoic acid (RA) for remission induction. Newly diagnosed patients received cytotoxic chemotherapy for consolidation, and previously treated patients received extended all-trans RA therapy, or a radionuclide-conjugated monoclonal antibody as post-remission treatment. Unlike studies in Europe, full-dose chemotherapy was not given during induction for patients who developed leukocytosis. Overall, 43 of 49 newly diagnosed patients (88%) and 25 of 30 previously treated patients (83%) achieved complete remission. We did not encounter de novo resistance to all-trans RA in any patient who was positive for PML/RAR-alpha rearrangements by reverse transcription polymerase chain reaction analysis. Ten patients died during induction from intracranial or pulmonary hemorrhage (six patients) or the 'retinoic acid syndrome' (four patients). The use of leukapheresis or low-dose chemotherapy (hydroxyurea or cytosine arabinoside) for drug-induced leukocytosis did not decrease early mortality. Compared to historical controls, early mortality was not affected by treatment with all-trans RA; however, both relapse-free and overall survival were significantly increased. Maintenance therapy with all-trans RA was associated with short remission duration, and relapses while taking the drug were universally associated with resistance to further retinoid treatment. We conclude that the use of all-trans RA for remission induction, with or without full-dose chemotherapy, has significantly increased the survival of patients with APL. While early mortality has not yet been reduced, the avoidance of full-dose chemotherapy during induction has significantly reduced early morbidity. The major outstanding clinical issue is the development of strategies that maximize safety in high-risk patients for whom intracranial hemorrhage remains the major cause of death.

Antigens, Surface↗
PubMed1993

Suramin for germ cell tumors. In vitro growth inhibition and results of a phase II trial.

BACKGROUND: Several studies have indicated a role for specific growth factors in the differentiation or deregulated growth of germ cell cancers. One proposed mechanism of antitumor activity for suramin is the inhibition of these tumor-derived growth factors. METHODS: Based on these data, the effects of suramin were studied on the growth of a monolayer culture of two human teratocarcinoma cell lines, NT2/D1 and N2102ep. These represented one cell line that was sensitive (NT2/D1) and one that was resistant (N2102ep) to the differentiation agent retinoic acid. These studies were followed by a Phase II trial of suramin in patients with germ cell tumors. Patients were treated with a continuous infusion of suramin. Dosing was determined by a nomogram based on weekly serum concentrations. RESULTS: Suramin inhibited the growth of both cell types in a dose-dependent fashion at a concentration attainable in patient plasma. This provided the rationale for a clinical trial of suramin in patients with cisplatin-refractory germ cell tumors. Fourteen patients were treated, and no complete or partial responses were observed. One patient achieved a prolonged decline in serum alpha-fetoprotein level without change in the size of a bidimensionally measurable retroperitoneal mass for more than 11 months. CONCLUSIONS: Despite the results of the in vitro studies, a Phase II trial failed to demonstrate significant antitumor activity for suramin in patients with cisplatin-refractory germ cell tumors. Although the dosing of suramin by the nomogram was not associated with neurotoxicity, the time needed to achieve therapeutic levels was lengthy, and the levels, once achieved, were of short duration. Thus, an alternative means of administration, i.e., by intermittent bolus administration, is being investigated in trials for patients with prostatic carcinoma. The lack of definitive efficacy for suramin in this trial has led the authors to consider other agents in Phase II trials for cisplatin-refractory germ cell tumor.

Adult↗
PubMed1993

Clinical efficacy of milbemycin oxime in the treatment of generalized demodicosis in adult dogs.

Thirty adult dogs with chronic generalized demodicosis were treated with oral administration of milbemycin oxime (0.52 to 3.8 mg/kg of body weight, q 24 h). Results of skin scrapings were used to determine whether administration of milbemycin should be continued or discontinued. Dogs that were free of clinical signs of demodicosis 12 months after administration of milbemycin was discontinued were considered cured. Sixteen dogs were cured, 5 dogs were never cleared of mites, and 9 dogs were cleared of mites, but relapsed after administration of milbemycin was discontinued. Adverse effects of milbemycin were rare and transient.

Animals↗
PubMed1993

Retinoic acid stimulates the protein kinase C pathway before activation of its beta-nuclear receptor during human teratocarcinoma differentiation.

We previously reported that protein kinase C (PKC) stimulation through phorbol ester (TPA) treatment enhances the effects of all-trans retinoic acid (RA) on immunophenotypic differentiation and RA nuclear receptor (RAR) activation in the multipotential human teratocarcinoma (TC) cell line NTera-2/clone D1 (abbreviated NT2/D1). This study extends prior work in NT2/D1 cells by demonstrating that PKC pathway activation is an early effect of RA treatment which regulates RAR transcriptional activity. RA activated the PKC pathway prior to induction of RAR-beta expression at 6 h, which is an established early marker of RAR activation in NT2/D1 cells. RA caused a transient 1.3-fold increase in intracellular diacylglycerol (DG) at 2 min and a translocation of the gamma isozyme of PKC (PKC-gamma) within 5 min. Transient co-transfection studies provided evidence that PKC pathway activation plays a role in the regulation of RAR-beta expression. In these studies a constitutively active PKC-gamma augmented the RA-mediated transactivation of a luciferase reporter containing the native RAR-beta promoter which has a retinoic-acid-response element (RARE). These findings reveal that PKC pathway activation is an early step in RA-mediated human TC differentiation and that PKC-gamma can potentiate the effects of RA on RAR transcriptional activation.

Cell Differentiation↗
PubMed1993

Detection of minimal residual disease in acute promyelocytic leukemia by a reverse transcription polymerase chain reaction assay for the PML/RAR-alpha fusion mRNA.

The characteristic reciprocal translocation t(15;17) of acute promyelocytic leukemia (APL) disrupts the PML gene on chromosome 15 and the retinoic acid receptor-alpha (RAR-alpha) gene on chromosome 17. PML/RAR-alpha fusion mRNAs are then transcribed and can be detected by a newly described reverse transcription polymerase chain reaction (RT-PCR) assay. Using RT followed by nested PCR amplification for PML/RAR-alpha, we serially evaluated bone marrow aspirates from patients with APL who were treated with all-trans retinoic acid (RA) for induction, followed by all-trans RA as maintenance or cytotoxic drugs as consolidation. At diagnosis, PML/RAR-alpha mRNA was detected in all patients. After initial therapy with all-trans RA, the RT-PCR assay remained positive after induction of complete remission in 31 of 32 evaluable patients. Maintenance treatment by all-trans RA alone was associated with persistent assay positivity and subsequent clinical relapse in 13 of 13 patients. By contrast, the test became negative in 19 of 20 newly diagnosed patients who received consolidation chemotherapy; the 1 patient who remained positive relapsed at 12 months. Three of the 19 assay-negative patients later converted to positive and subsequently relapsed; the remaining 16 patients have remained RT-PCR negative in sustained first remission, with a median follow-up duration that exceeds 24 months (range, 12+ to 34+ months). Despite induction of complete remission in a high proportion of patients, all-trans RA rarely eradicates molecular evidence of disease in patients with APL; however, subsequent treatment with cytotoxic chemotherapy frequently converts the RT-PCR assay for PML/RAR-alpha to negative. Serial negative tests are associated with prolonged disease-free survival, whereas persistence of a positive test after treatment is highly correlated with subsequent relapse. This test identifies patients in remission at high risk for relapse who may benefit from additional antileukemic therapy.

Antineoplastic Agents↗
PubMed1993

Antitumor effects of doxorubicin in combination with anti-epidermal growth factor receptor monoclonal antibodies.

BACKGROUND: A variety of human tumors frequently express high levels of epidermal growth factor (EGF) receptor and its ligand, transforming growth factor alpha (TGF-alpha), which in some tumors is associated with poor prognosis. Monoclonal antibodies (MAbs) that block the binding of TGF-alpha or EGF to the receptor can inhibit proliferation of tumor cells that express the receptor. Studies suggest that these MAbs may enhance the antitumor effects of chemotherapy. PURPOSE: Our purpose was to study, in vitro and in vivo, the antitumor effects of doxorubicin in combination with anti-EGF receptor MAbs against tumor cells expressing high levels of EGF receptor. Our goal was to achieve maximum initial cytoreduction with high-dose doxorubicin in association with prolonged blockade of EGF receptor with MAbs. METHODS: Anti-EGF receptor MAbs 528 (isotype IgG2a) and 225 (isotype IgG1) were used in combination with doxorubicin against cells from human A431 squamous cell carcinoma and human MDA-468 breast adenocarcinoma. Both A431 and MDA-468 cells express high levels of EGF receptors and TGF-alpha. Cultured cells were treated with doxorubicin (range, 0-10 nM) in the presence or absence of MAb 528 or 225 (range, 0-30 nM). At 48 hours, doxorubicin-containing medium was removed, and treatment with antibody was continued for 5 days, when cell proliferation assays were performed. The activity of the agents and the combinations against well-established xenografts in BALB/c nude mice was also studied. In nude mice, doxorubicin was given at doses of 50-100 micrograms/20 g body weight on 2 successive days, and MAbs 528 and 225 were given at a dose range of 0-2 mg intraperitoneally twice a week. RESULTS: MAbs 528 and 225 both enhanced the antitumor effects of doxorubicin against A431 and MDA-468 tumor cells, producing additive growth suppression in cell cultures. MAb 528 increased the antitumor effects of doxorubicin by 32%-42%, and similar results were obtained with MAb 225. In BALB/c athymic mice, the treatment of well-established xenografts with either doxorubicin or anti-EGF receptor MAb alone temporarily inhibited growth, but the combination of both agents substantially enhanced antitumor activity over that of doxorubicin alone in A431 and MDA-468 cell xenografts. The combination treatment of mice bearing A431 xenografts resulted in tumor eradication of 40%-100% in the surviving mice in several independent experiments. The enhanced antitumor activity was dose dependent. CONCLUSIONS: Our results suggest that anti-EGF receptor MAbs substantially enhance the effects of doxorubicin against well-established xenografts of tumor cells expressing high levels of EGF receptors. IMPLICATIONS: Clinical trials with anti-EGF receptor MAbs are being conducted, and trials with anti-EGF receptor MAbs combined with doxorubicin are planned.

Adenocarcinoma↗
PubMed1993

Regulation of myeloblastin messenger RNA expression in myeloid leukemia cells treated with all-trans retinoic acid.

Retinoic acid is known to induce differentiation of human myeloid leukemia cells in vitro. Recently, all-trans retinoic acid has been used to induce remissions in patients with acute promyelocytic leukemia, probably through differentiation of the leukemia cells. Myeloblastin (mbn) is a protease that has been identified in the human leukemia cell line HL-60. Downregulation of this protease can inhibit proliferation and induce differentiation of HL-60-derived leukemia cells. Here we have investigated the regulation of mbn messenger RNA (mRNA) expression in two human leukemia cell lines, HL-60 and NB4, treated with all-trans retinoic acid. Under this treatment, downregulation of mbn mRNA was observed in both cell lines, but was considerably delayed in NB4 cells that carry the t(15;17) translocation characteristic of acute promyelocytic leukemia. We have found that multiple mechanisms were involved in the control of mbn mRNA expression. These mechanisms were different in HL-60 and NB4 cells. Our results show that in HL-60 cells, all-trans retinoic acid rapidly decreased transcription of mbn. In contrast, in the t(15;17)-positive NB4 cells treated with all-trans retinoic acid, upregulation of mbn mRNA expression was followed by a late downregulation, both achieved via posttranscriptional mechanisms.

Cell Cycle↗
PubMed1993

Comorbidity in pregnant patients in a psychiatric inpatient setting.

The impact of substance abuse on mental illness is substantial. The consequences of comorbidity on pregnant women has not been previously reviewed. This paper discusses the implications of interrelationship of substance use and mental illness on pregnancy. We present data from a retrospective study of pregnant women admitted for psychiatric care, reviewing the relationships of comorbidity to their demographic, psychiatric, and obstetrical histories and follow-up prenatal care.

Adult↗
PubMed1993

Pulsed-field gel electrophoresis analysis of retinoic acid receptor-alpha and promyelocytic leukemia rearrangements. Detection of the t(15;17) translocation in the diagnosis of acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is characterized cytogenetically by a balanced reciprocal chromosomal translocation t(15;17) (q22;q21). This translocation involves the retinoic acid receptor-alpha (RAR-alpha) on chromosome 17 and the promyelocytic leukemia locus (PML) on chromosome 15 and results in the transcription of novel fusion messenger RNAs. In this study, pulsed-field gel electrophoresis (PFGE) was applied to the detection of the t(15;17) translocation in twenty-six clinical specimens cytologically diagnosed by French-American-British criteria as APL. This technique could readily be applied to both fresh and nonviably frozen tumor samples. In 24 of 26 samples, rearrangements of the PML and RAR-alpha, loci could be detected by Southern blotting after digestion with MluI and BssHII. Furthermore, co-migration of the rearranged fragments, detected by hybridization to probes for the PML and RAR-alpha genes, demonstrated that these loci were juxtaposed. The translocation was detected in specimens at the time of initial diagnosis, on differentiation therapy with retinoic acid and at the time of relapse. The diagnostic accuracy was compared to cytogenetics and the reverse transcriptase-polymerase chain reaction for the novel PML-RAR-alpha fusion transcript. The samples from two patients were negative by all three diagnostic methods, and both of these patients failed to respond to all-trans retinoic acid. In the other 24 APL samples, cytogenetics was positive in only 76.9% of the cases, whereas both reverse transcriptase-polymerase chain reaction and PFGE methods detected the translocation in 100% of the cases. Thus, PFGE can readily detect the t(15;17) translocation in both viable and nonviable clinical specimens and can improve the diagnostic accuracy of morphology and cytogenetics in APL. In contrast to conventional electrophoresis based on rearrangement of RAR-alpha, the ability to demonstrate directly co-migration of the PML and RAR-alpha loci enables this method to distinguish the t(15;17) translocation from variant translocations such as the t(11;15). Because PFGE can be performed on nonviable, frozen tumor samples, it could be diagnostically useful in APL when the RNA-based reverse transcriptase-polymerase chain reaction cannot be performed.

Chromosomes, Human, Pair 15↗
PubMed1993

Over-expression of transforming growth factor alpha antagonizes the anti-tumorigenic but not the differentiation actions of retinoic acid in a human teratocarcinoma cell.

All-trans retinoic acid (RA) treatment of the multipotent human teratocarcinoma (TC) cell line NTERA-2 clone D1 (abbreviated NT2/D1) induces a neuronal phenotype and other cell lineages. NT2/D1 cells basally express transforming growth factor alpha (TGF-alpha) mRNA and secreted protein. After RA-treatment TGF-alpha expression is markedly reduced. This decline in TGF-alpha expression accompanies the induction of the neuronal phenotype and a marked reduction of tumorigenicity in athymic mice. This suggested a causal link between reduced TGF-alpha expression and the induced differentiation or loss of tumorigenicity of these RA-treated TC cells. To evaluate this possibility, an RA-refractory NT2/D1 subclone was analysed. This subclone, designated NT2/D1-R1, failed to induce differentiation or to decrease TGF-alpha expression despite RA treatment. To further explore the relationship between TGF-alpha expression and RA actions in this human TC cell, a TGF-alpha cDNA was stably transfected and expressed in NT2/D1 cells. RA-treatment of independently obtained TGF-alpha over-expressing clones and a representative control transfectant only expressing the neomycin resistance gene produced a neuronal phenotype similar to parental NT2/D1 cells as assessed by morphologic, immunophenotypic, and gene expression markers of differentiation. RA-treatment of these clones also induced a G1 arrest similar to parental cells. However, only the TGF-alpha over-expressing clones that secreted high levels of TGF-alpha protein into the conditioned media before and after RA treatment still developed tumors in athymic mice despite prior exposure to these cells to RA. This finding demonstrates that TGF-alpha can inhibit the anti-tumorigenic effects of RA in human TCs. Thus, over-expression of a single growth factor that normally declines with RA treatment antagonizes the anti-tumorigenic but not the differentiation actions of RA in this human tumor cell.

Animals↗
PubMed1993

Retinoic acid and its rearranged receptor in the treatment of acute promyelocytic leukemia.

APL is a unique clinical example where a defined molecular genetic defect appears involved in both the pathogenesis and treatment of a human leukemia. The consistent finding that RA induces remissions in APL is especially notable, since treatment involves an oral formulation of RA. The clinical responses are linked to leukemic cell maturation, suggesting a noncytotoxic mechanism of RA action. This provides a rationale for combining cytotoxic and cytodifferentiation agents in future clinical trials. Despite high initial CR rates with continuous RA therapy, relapses frequently occur. Pharmacologic mechanisms of resistance to RA therapy are implicated in clinical resistance. Future work will explore if this resistance can be overcome and how genetic mechanisms contribute to clinical RA resistance in APL. The exciting convergence of clinical and basic information in PL has led to new insights into the molecular nature of this leukemia. The discovery that RAR-alpha is rearranged in the t(15,17) provides an opportunity to study how this rearrangement is involved in oncogenesis and treatment response in APL. The application of RT-PCR assays for this molecular rearrangement will be useful in the diagnosis and subsequent tailoring of postremission therapy in APL. Whether APL serves as a paradigm for cytodifferentiation therapy remains to be seen. However, it is encouraging that 13-cis-retinoic acid in combination with alpha interferon is an active therapy in squamous cell carcinomas of the cervix and skin. Although the mechanisms responsible for these clinical responses are unknown, they highlight the need to learn how RA works and when it should be used to treat cancer patients.

Base Sequence↗
PubMed1993

Medical management of allergic pruritus in the cat, with emphasis on feline atopy.

Pruritus associated with allergic skin diseases is an important reason for consultation in feline medicine. The pathophysiology of pruritus is poorly understood in the cat, but histamine and eicosanoids appear to be important mediators. The medical management of allergic pruritus in cats, especially those with atopy, using glucocorticoids, antihistamines, omega-3/omega-6 fatty acid-containing products, and combinations thereof is discussed.

Animals↗
PubMed1993

Nonsteroidal anti-inflammatory agents in the management of canine allergic pruritus.

Pruritus associated with allergic skin diseases is an important reason for consultation in canine medicine. The pathophysiology of pruritus is poorly understood in the dog, but histamine, leukotrienes, and prostaglandins appear to be important mediators. The medical management of allergic pruritus in dogs with nonsteroidal anti-inflammatory agents is discussed. Antihistamines, tricyclic antidepressants, and omega-3/omega-6 fatty acid-containing products are often useful, either as single agents, in combinations, or for reducing glucocorticoid requirements.

Animals↗
PubMed1992

Phosphorylation of carbovir enantiomers by cellular enzymes determines the stereoselectivity of antiviral activity.

Two enantiomers of carbovir, a carbocyclic analog of 2',3'-dideoxyguanosine, were compared with respect to their phosphorylation and the phosphorylation of their nucleotides by mammalian enzymes. 5'-Nucleotidase catalyzed the phosphorylation of (-)-carbovir, which is active against HIV (human immunodeficiency virus), but did not phosphorylate (+)-carbovir. (-)-Carbovir monophosphate was 7,000 times more efficient as a substrate for GMP kinase than was (+)-carbovir monophosphate. Pyruvate kinase, phosphoglycerate kinase, and creatine kinase phosphorylated both enantiomers of carbovir diphosphate at similar rates. Nucleoside-diphosphate kinase preferentially phosphorylated the (-)-enantiomer. Both enantiomers of carbovir triphosphate were substrates and alternative substrate inhibitors of HIV reverse transcriptase. Thus, the contrasting HIV-inhibitory activities of carbovir enantiomers were due to differential phosphorylation by cellular enzymes and not due to enantioselectivity of HIV reverse transcriptase.

Antiviral Agents↗
PubMed1992

Enantiomeric selectivity of carbovir transport.

Carbovir (9-[4 alpha-(hydroxymethyl)cyclopent-2-ene-1 alpha-yl]guanine) (CBV) is a carbocyclic analogue of 2',3'-dideoxyguanosine that exhibits potent and selective in vitro activity against human immunodeficiency virus. Antiviral activity is associated with only the (-)-enantiomer. The transport characteristics of both (-)-CBV and (+)-CBV were investigated in human erythrocytes at 37 degrees C using a papaverine-stop assay. The influx of both enantiomers appeared saturable and was inhibited greater than 90% by a combination of adenine (a low Km permeant of the nucleobase carrier) and dilazep (a potent inhibitor of nucleoside transport). The influx of (-)-CBV and (+)-CBV proceeded primarily via the nucleobase carrier with Vmax (picomoles/second/5 microliters of cells)/Km (millimolar) values of 17/0.12 and 140/1.9, respectively. To a lesser extent, the influx of (-)-CBV and (+)-CBV also occurred via the nucleoside transporter. Although both compounds exhibited a similar low affinity for this latter carrier (Km approximately 2 mM), the Vmax for (-)-CBV influx was approximately 4-fold higher than the Vmax for (+)-CBV influx. We conclude that both CBV enantiomers enter human erythrocytes by two transporters that are enantiomerically selective.

Antiviral Agents↗
PubMed1992

3'-Azido-3',5'-dideoxythymidine-5'-methylphosphonic acid diphosphate: synthesis and HIV-1 reverse transcriptase inhibition.

3'-Azido-3'-deoxythymidine-5'-phosphonate was synthesized by a five-step reaction sequence. The 5'-phosphonate was inactive against HIV-1 in MT4 cells. The absence of activity against HIV-1 was at least partially explained by demonstrating that the Km value for the 5'-deoxy-5'-methylphosphonic acid diphosphate analog with HIV-1 reverse transcriptase (RT) was 320-fold greater than the Km value for 3'-azido-3'- deoxythymidine-5'-triphosphate (AZTTP), and the kcat value for the 5'-deoxy-5'-methylphosphonic acid diphosphate analog was one-seventh the value for AZTTP. These differences in kinetic constants were due to a change in the rate-determining step from dissociation of the RT chain-terminated template-primer complex to the catalytic step. Thus, substitution of a methylene group for the 5'-oxygen atom of AZTTP resulted in an 1800-fold reduction in the rate constant for RT-catalyzed phosphodiester bond formation.

Antiviral Agents↗