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R J Mayer

Publications and source records attributed to R J Mayer.

At least 163 records · Page 9Linked to original sources
PubMed1991

A prospective evaluation of hepatic resection for colorectal carcinoma metastases to the liver: Gastrointestinal Tumor Study Group Protocol 6584.

We report here the results of the first multiinstitutional prospective evaluation of patients considered to have potentially resectable hepatic metastases from colorectal carcinoma. One hundred fifty-six patients were enrolled from 15 institutions. Six patients were subsequently excluded. One hundred fifty patients underwent surgery and are evaluable for analysis (median follow-up time, 3.1 years; range, 4 months to 5.1 years). Curative resection could be performed on 46% of patients (69 of 150), noncurative resection on 12% (18 of 150), while 42% were found to be unresectable (63 of 150). Thirty-day surgical mortality and morbidity rates in patients with attempted resection were 2.7% and 13%, respectively. The curative resection group was observed to have an improved median survival (37.1 months) compared with the noncurative resection group (21.2 months) and the unresectable group (16.5 months) (P less than .01). Computed tomographic (CT) scan was a poor predictor for resectability, and age was not a contraindication to curative resection. Preoperative carcinoembryonic antigen (CEA) values were also a poor predictor for resectability. However, the median CEA value 61 to 180 days postsurgery was significantly higher in unresectable patients compared with median CEA levels in noncuratively and curatively resected groups (P less than .01). Our results imply that curative resection leads to an increase in median survival. Noncurative resection provides no benefit to asymptomatic patients, since unresectable and noncurative resection groups have similar life expectancies. Longer follow-up will be needed to demonstrate the ultimate impact of curative resection on survival.

Adenocarcinoma↗
PubMed1991

Ubiquitin and the lysosome system: molecular immunopathology reveals the connection.

Considerable advances in our understanding of the molecular pathology of the major human neurodegenerative diseases have been made by the use of ubiquitin immunocytochemistry. The technique demonstrates that filamentous inclusions and vacuoles contain ubiquitin-protein conjugates. The molecular structure of the filaments and the morphological type of vacuoles is not completely understood but there is evidence that some of the filamentous inclusions contain intermediate filaments and the perinuclear distribution of the vacuoles resemble the distribution of intraneuronal lysosomes. Intermediate filaments and lysosomes are involved in the sequestration and degradation of viral membrane proteins in tissue culture cells. Immunogold electron microscopical and biochemical evidence indicates that ubiquitin-protein conjugates are normally considerably enriched in the lysosomes of fibroblasts relative to all other organelles. Immunogold electron microscopy shows a similar enrichment of ubiquitin-protein conjugates in the dense lysosomes of granulocytic precursor cells in the bone marrow. Filamentous inclusions showing several of the features seen in inclusions in the neurodegenerative diseases are seen in Epstein-Barr virus transformed lymphoblastoid cells. Immunohistochemistry shows that the inclusions contain vimentin intermediate filaments, the latent membrane transforming protein of the virus, ubiquitin-protein conjugates, and a heat-shock protein 70 (hsp 70). Immunohistochemistry and immunogold electron microscopy demonstrate that the latent membrane protein, ubiquitin-protein conjugates and hsp 70 are in lysosomes entwined in an intermediate filament cage centred on the microtubule organising centre. The implications of the combined observations for our understanding of the cell stress response in degenerating neurones and in virally infected cells are discussed.

Heat-Shock Proteins↗
PubMed1991

The role of protein ubiquitination in neurodegenerative disease.

Ubiquitin immunocytochemistry with an antiserum which reacts with ubiquitin-protein conjugates demonstrates the presence of ubiquitinated proteins in filamentous inclusions found in neurones in the major human neurodegenerative diseases, i.e. Alzheimer's disease, diffuse Lewy body disease, motor neurone disease. Ubiquitin immunohistochemistry has revolutionized the neuropathological diagnosis of dementia showing that diffuse Lewy body disease is not, as previously supposed, a rare cause of dementia. The filamentous inclusions in neurones in the human neurodegenerative diseases can be divided into at least two types based on recent immunocytochemical studies. We have shown that a ubiquitin-carboxyl terminal hydrolase is present in Lewy bodies but not in neurofibrillary tangles in Alzheimer's disease. This observation is significant since it indicates that molecular pathological mechanisms in neurones in diffuse Lewy body disease are fundamentally different to Alzheimer's disease. Ubiquitin-protein conjugates are also found in vacuoles in areas of granulovacuolar degeneration in hippocampal neurones in Alzheimer's disease and in granulovacuoles in neurones of scrapie infected mouse brain. These locations suggest that ubiquitinated protein are present in the lysosome-related system of neurones. We have recently shown that ubiquitin-protein conjugates are indeed enriched some 12-fold in the lysosomes of normal fibroblasts and lymphocytes.

Brain Diseases↗
PubMed1991

Simultaneous administration of granulocyte-macrophage colony-stimulating factor and cytosine arabinoside for the treatment of relapsed acute myeloid leukemia.

The treatment of patients with relapsed or refractory acute myeloid leukemia (AML) with high dose cytosine arabinoside (ara-C) results in short-lived complete response rates of 30-50%. We have previously shown that entry of myeloid leukemic cells into S phase can be accelerated in vitro through the use of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF), resulting in enhancement of ara-C-mediated cytotoxicity. In order to evaluate the in vivo biological and clinical effects of this strategy in patients with high risk AML, we treated three patients with either refractory or relapsed disease with a continuous infusion of rhGM-CSF (0.45 micrograms/kg/h aglycoprotein) for 18 h, followed by the institution of high dose ara-C and continuation of rhGM-CSF throughout the 4 day duration of ara-C treatment. Prior to therapy, no patient had detectable levels of circulating rhGM-CSF, and there was no evidence of GM-CSF receptor occupancy in leukemic myeloblasts. After 18 h of rhGM-CSF therapy, all patients had biologically active levels of circulating rhGM-CSF (7.9-12.0 ng/ml), and two patients showed a significant degree of leukemic GM-CSF receptor occupancy without evidence of GM-CSF receptor down-regulation. A significant rise in the S phase fraction of leukemic myeloblasts was observed at 18 h of rhGM-CSF treatment in all three patients (29-56% increment). The toxicity of combined rhGM-CSF/ara-C therapy included pericarditis and cerebellar degeneration in one patient, fever and mild renal dysfunction in two patients, and mild hepatic dysfunction in all three patients. Each patient showed a transient rise in the absolute neutrophil and blast count during rhGM-CSF/ara-C administration, followed by profound, but clinically tolerable, myelosuppression. No patient developed clinical evidence of leukostasis. There was one death related to pericardial tamponade, one death related to refractory disease, and one clinical and cytogenetic remission. These results suggest that exogenously administered rhGM-CSF is capable of rapidly mobilizing leukemic cells into S phase in vivo and theoretically should be useful in overcoming kinetic resistance to ara-C. Clinical trials of this regimen in patients with high risk AML who are not already pharmacologically resistant to ara-C are warranted.

Acute Disease↗
PubMed1991

Systemic therapy for colorectal cancer: an overview.

The systemic management of patients with colorectal cancer continues to center on the use of 5-fluorouracil (5-FU). In the setting of metastatic disease, parenteral 5-FU has been shown to be superior to oral 5-FU; however, survival duration seems similar regardless of whether parenteral 5-FU is administered in a "loading schedule," weekly, or in a continuous-infusion regimen. The addition of other cytotoxic agents, such as semustine (methyl-CCNU) and/or mitomycin C, to 5-FU does not appear to be beneficial. Recent efforts have been directed toward enhancing the activity of 5-FU by (1) increasing its incorporation into RNA through pretreatment with methotrexate or phosphonoacetyl-L-aspartate (PALA), (2) enhancing DNA synthesis inhibition via the concomitant administration of folinic acid, and (3) an undetermined modulatory action by the addition of alpha-interferon. These pharmacologic approaches are being compared in ongoing cooperative group trials. The results of five randomized trials assessing the value of intra-arterial, hepatic infusions of 5-FU or 5-fluorodeoxyuridine have demonstrated that regional chemotherapy increases the likelihood of a hepatic response when compared with systemic treatment, but has little effect on survival and is associated with significant toxicity. Recent adjuvant chemotherapy trials have indicated both a decrease in recurrence and a prolongation in survival when chemotherapy (5-FU + levamisole) is administered to patients with stage C colon cancer; and combined radiation therapy and chemotherapy is given to patients with stages B2 and C rectal cancer.

Chemotherapy, Adjuvant↗
PubMed1991

Phase III trial of brief intensive treatment of adult acute lymphocytic leukemia comparing daunorubicin and mitoxantrone: a CALGB Study.

This paper reports a study of the Cancer and Leukemia Group B (CALGB) comparing daunorubicin (DNR) or mitoxantrone (DHAD) in induction followed by multidrug intensification over 8 months in adult patients with acute lymphocytic leukemia (ALL). A total of 164 newly diagnosed patients were randomly assigned to either DNR or DHAD plus vincristine, prednisone and methotrexate given intravenously (i.v.) and interthecally (i.t.). Patients received four more intensification courses of chemotherapy and then all therapy was stopped. Central nervous system (CNS) prophylaxis consisted of nine infusions of intermediate dose methotrexate (MTX) and intrathecal MTX. DHAD and DNR were equally effective in producing complete remissions (63 and 65%, respectively). The estimated median remission duration is 10.2 and 12.3 months for the DHAD and DNR arms, respectively (p = 0.56). This study was stopped earlier than planned when it became apparent that remission duration for both arms was shorter than seen in our prior study in which all patients received more than 1 year of maintenance therapy. The estimated median survival is 18.3 and 20.6 months for the DHAD and DNR arms, respectively (p = 0.90). Younger patients and patients with a pre-treatment white blood count of less than 30,000/microliters had a significantly longer remission duration and survival. Eleven per cent of patients who achieved a complete remission have had a CNS relapse to date, which is not different from the rate in our prior study using cranial irradiation and i.t. MTX, implying that intermediate dose MTX with i.t. MTX may be as effective as cranial irradiation and i.t. MTX. This study suggests that some form of maintenance chemotherapy is required for the eradication of residual leukemia cells.

Adolescent↗
PubMed1990

Inhibition of 3-hydroxy-3-methylglutaryl coenzyme A synthase by antibiotic 1233A and other beta-lactones.

3-Hydroxy-3-methylglutaryl CoA synthase was shown to be inhibited in a time-dependent, irreversible manner by compounds containing the substituted beta-lactone functionality found in the natural product 1233A. The rate of inactivation (kinact) was found to approach the rate of catalysis (kcat). The inactivation was irreversible over several hours. A related compound lacking the hydroxymethyl substituent on the beta-lactone ring is a reversible inhibitor and is competitive with respect to acetylCoA. The results are consistent with beta-lactone ring opening by the active site Cys to form an enzyme bound thioester.

Acetates↗
PubMed1990

Slow binding inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A reductase.

The mechanism of slow binding inhibition of 3-hydroxy-3-methylglutaryl- coenzyme A reductase by lovastatin, fluindostatin, and related compounds was studied. Several of these compounds, including lovastatin, were found to be slow binding, while other less potent inhibitors were not. From a comparison of kinetic parameters obtained by steady-state measurements and progress curve analysis, it was concluded that the slow binding inhibitors bind by a mechanism which is more accurately described by biphasic binding than by single-step binding. The overall association rates of the slow binding inhibitors range from 1 x 10(6) to 4 x 10(-7) M-1 s-1, and the dissociation rates are in the range of 10(-3) s-1. The structures of slow binding and reversible inhibitors were compared by using molecular modeling methods. From these comparisons, it was proposed that the slow binding and very potent inhibition of, for instance, lovastatin, is not simply a result of binding of a transition state or reaction intermediate analogue. The various lipophilic groups of the inhibitors that do not seem to be related to structural features of the substrate may also play a crucial role in determining the mechanism of binding of HMGR inhibitors.

Chemical Phenomena↗
PubMed1990

Ubiquitinated protein conjugates are specifically enriched in the lysosomal system of fibroblasts.

Ubiquitin-protein conjugates are found by immunogold electron microscopy to be enriched (12-fold) in the lysosomal compartment of 3T3-L1 fibroblasts. Treatment of fibroblasts with the cysteine protease inhibitor E-64 leads to an expansion of the lysosomal compartment and as a result an increase in the cellular content of ubiquitin-protein conjugates. There is no change in the specific enrichment of ubiquitin-protein conjugates in the lysosomal compartment following E-64 treatment. The results suggest that some ubiquitin-protein conjugates may normally be degraded lysosomally following sequestration by microautophagy and imply that protein ubiquitination may be one of the signals for protein uptake into lysosomes.

Cell Line↗
PubMed1990

Treatment of relapsed and refractory acute myeloid leukemia with diaziquone and mitoxantrone: a CALGB phase I study.

Twenty-one patients with relapsed or refractory acute myeloid leukemia (AML) were treated with mitoxantrone (12 mg/m2/day, days 1-3) and diaziquone (continuous infusion days 1-5). The dosage of diaziquone was increased for sequential cohorts of seven patients from 20 mg/m2/day to 24 mg/m2/day, and finally to 28 mg/m2/day to determine the maximum tolerated dose for this chemotherapy combination. Myelosuppression was the dose-limiting toxicity. The median time to recovery of blood counts was greater at the highest dose of diaziquone (48 days) than at the lower two doses (31 and 28 days). Other toxic effects were minimal. Overall, 9/21 (43%, 95% confidence interval, 0.22 to 0.66) patients achieved complete remission. We conclude that this combination of drugs shows sufficient antileukemic activity with acceptable toxicity to warrant further trials.

Adult↗
PubMed1990

Ubiquitin carboxyl-terminal hydrolase (PGP 9.5) is selectively present in ubiquitinated inclusion bodies characteristic of human neurodegenerative diseases.

The recent discovery that brain PGP 9.5 is a ubiquitin carboxyl-terminal hydrolase suggests that the role of this protein should be studied in relation to ubiquitinated cellular inclusions characteristic of several chronic human degenerative diseases. Formalin-fixed, paraffin-processed sections known to contain ubiquitin-protein conjugate immunoreactivity in cortical Lewy bodies, neurofibrillary tangles, Rosenthal fibres, Pick bodies, spinal inclusions in motor neurone disease, and Mallory's hyaline in alcoholic liver disease were immunostained to localize PGP 9.5. The majority of cortical Lewy bodies in diffuse Lewy body disease showed immunoreactivity for PGP 9.5. In Alzheimer's disease, only a minority of loosely arranged globose-type neurofibrillary tangles were immunostained together with a minority of neurites surrounding senile plaques. In cerebellar astrocytomas, the periphery of the majority of Rosenthal fibers was immunostained in addition to strong diffuse cytoplasmic immunostaining in some astrocytes lacking apparent Rosenthal fibers. In Pick's disease, there was no immunostaining of inclusions but there was intense immunostaining of swollen Pick cells. No spinal inclusions in motor neurone disease were stained; however, anterior horn neurones appear to show increased levels of PGP 9.5 compared with those from control cases. No immunostaining of hepatic Mallory's hyaline was demonstrable, which accords with suggestions that PGP 9.5 is a tissue-specific ubiquitin C-terminal hydrolase isoenzyme. The differential detection of a ubiquitin C-terminal hydrolase in different forms of ubiquitinated inclusion body in the nervous system may form the basis of a method for assessment of the staging of inclusion body biogenesis and give insight into the dynamics of inclusion body formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Alzheimer Disease↗
PubMed1990

Ubiquitin conjugate immunoreactivity in the brains of scrapie infected mice.

Sections of brain from normal mice or clinically-ill mice infected with either the 87V or the ME7 strains of sheep scrapie were immunostained to show the localization of ubiquitin-protein conjugates or a specific marker of disease, the scrapie-associated fibril protein (PrP). In both scrapie models immunoreactive ubiquitin-protein conjugates were seen in thread-like structures found throughout the neuropil, in inclusion bodies within vacuolated neurones, and in areas surrounding anti-PrP positive amyloid plaques. The PrP protein was visualized in diffuse deposits in highly vacuolated parts of the scrapie-affected brain, and focally in amyloid plaques, microglia and neuronal processes. The ubiquitin-protein conjugate staining of scrapie amyloid plaques is very similar to that seen in the plaques of Alzheimer's disease. The ubiquitinated intraneuronal inclusion bodies seen in scrapie resemble the granulovacuolar lesions also seen in Alzheimer's disease, but appear much larger and possibly correspond to material in giant autophagic vacuoles. We suggest that these inclusions may be the result of ubiquitinated abnormal proteins being directed to the lysosomal system, and that scrapie and Alzheimer's disease share at least some common processes of neurodegeneration.

Amyloid↗
PubMed1990

Acute leukemias in adults: an overview of recent strategies.

In 1989, 65%-75% of previously untreated adults with ALL or AML may be expected to enter complete remission. Approximately 40% of these completely responding patients, whether they are treated with intensive chemotherapy, intensive chemotherapy followed by autologous bone marrow transplantation, or allogeneic bone marrow transplantation, remain disease-free after 3 years of follow-up. As such, the likelihood for cure for adults with acute leukemia is approximately 25%-30%. At the present time, no new chemotherapeutic agents of significant importance are on the horizon. Furthermore, it seems doubtful that the mere juggling of drug doses will have any measurable effect on treatment outcome. The use of hematopoietic growth factors, either to allow added tolerance of intensive therapy or to synchronize leukemic cells kinetically, is now under study. Perhaps the most promising area of present investigations deals with immune manipulation. The administration of immunotoxins (a drug or a cell poison chemically linked to a leukemia-related monoclonal antibody) has been associated with promising results in eradicating minimal residual disease in animal model systems. Similarly, attempts at harnessing the graft-versus-leukemia effect without the eligibility restrictions and toxicities associated with the allograft procedure, through the use of lymphokines as enhancers of natural killer cell activity, have also proven to be effective in pre-clinical trials. With the availability of hematopoietic growth factors, immunotoxins, and lymphokines, clinical research in acute leukemia in the future will no longer focus on cytotoxic drugs alone but rather on how the addition of biological agents can prolong the duration of complete remission and increase the potential for cure.

Bone Marrow Transplantation↗
PubMed1990

Ubiquitin, cell stress and diseases of the nervous system.

Cells, including those of the nervous system, respond to damage by an increase in the synthesis of a family of proteins called 'stress proteins' which are amongst the most conserved gene products in evolution suggesting fundamental roles in cell metabolism. Stress-induced proteins have functions in normal cells, particularly for the importation of protein into membrane-limited organelles, and their up-regulation following stress is thought to be cytoprotective, by protecting proteins and organelles from damage. Ubiquitin is an important protein induced by cell stress. It is only found in nucleated cells and has several known functions; the most investigated being as a co-factor for the non-lysosomal intracellular degradation of abnormal or short lived proteins. Morphological studies using immunohistochemistry to localize ubiquitin protein conjugates have revealed that ubiquitin is a component of many of the filamentous inclusion bodies characteristic of neurodegenerative diseases, suggesting activation of a common neuronal response in this type of disease process. Immunohistochemical localization of ubiquitin conjugates has provided a new tool for the sensitive detection of such inclusions and has resulted in the identification of novel inclusion bodies in all cases of motor neuron disease. Preliminary work on enzymes involved in ubiquitin metabolism suggest that there are several possible mechanisms for the formation of inclusion bodies and may provide indirect evidence for the dynamics of inclusion body formation. Work in other areas of pathology indicate important roles for the stress proteins in immune surveillance and autoimmunity and it is likely that the general principles which are currently evolving will also have an impact in neuropathology.

Animals↗
PubMed1990

The unique aspects of acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) accounts for approximately 10% of cases of acute myeloid leukemia (AML). Distinctive features of this disorder at the time of diagnosis include leukopenia coexisting with a marrow replaced with granulated dysplastic promyelocytes, disseminated intravascular coagulopathy, lack of Ia (HLA-DR) antigen expression, and translocation between the long arms of chromosomes 15 and 17 (t[15;17]). Heparin is widely but not universally used to interfere with the coagulopathy during the initial phases of treatment. Serial bone marrow examinations during the induction period demonstrate the achievement of remission despite the persistence of malignant-appearing promyelocytes. Patients with APL are generally younger than those with other subtypes of AML, have a 70% to 80% likelihood of entering remission, and are thought to have a more favorable prognosis than other individuals with AML. Remission may be achieved with a conventional anthracycline-cytarabine combination, anthracycline alone, or, apparently, all-trans retinoic acid. Genes potentially important in myeloid differentiation such as granulocyte colony-stimulating factor (G-CSF) and myeloperoxidase are located close to the breakpoint in the t(15;17) but have not been conclusively shown to be rearranged in the translocation. A better understanding of the unique aspects of APL may well shed light on the pathogenetic processes of AML.

Blood Coagulation↗
PubMed1990

Intensive chemotherapy versus allogeneic bone marrow transplantation in first-remission acute myeloid leukemia.

At present, using the most contemporary management techniques, it would appear that allogeneic bone marrow transplantation and intensive chemotherapy offer a roughly equivalent potential for curing adult patients with AML in first remission. Each form of treatment has drawbacks--the limited eligibility and continued high rate of early death associated with the allogeneic transplant procedure and the significantly greater likelihood of relapse, as well as the risk for drug-induced, life-threatening toxicities observed following the administration of chemotherapy. Future efforts should be directed at improving each of these treatment techniques, perhaps through kinetic synchronization of leukemic cells by hematopoietic growth factors to make chemotherapy more potent and by better understanding and then harnessing the "graft-versus-leukemia" effect which appears so instrumental in reducing the relapse rate following allografting.

Adult↗