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Biomedical subjects

G L Tritsch

Publications and source records attributed to G L Tritsch.

At least 37 records · Page 2Linked to original sources
PubMed1980

Adenosine deaminase specific activity in normal, benign hypertrophied and neoplastic human prostate tissue.

The finding that deficiency in the purine salvage pathway enzyme, adenosine deaminase (ADA), is associated with immunodeficiency suggests that this enzyme may be crucial for normal function of immunocompetent cells in man. We have therefore examined ADA activity in human prostatic tissue. Mean values were as follows: normal tissue, 0.37 mumol substrate turned over/h/mg protein; carcinoma, 0.33; benign prostatic hypertrophy (BPH), 1.22. ADA activity in normal and carcinoma prostate tissue differed significantly from BPH (p = 0.001), but were individually indistinguishable. Thus, there may be a cellular level of immunostimulation in BPH relative to normal prostatic tissue which is no longer detectable in overt carcinoma.

Adenosine Deaminase↗
PubMed1980

Positive correlation between adenosine deaminase activity and superoxide formation during phagocytosis.

Phagocytosis and membrane perturbation in mouse macrophages results in an increased superoxide ion production which is in direct proportion to the concomitant increase in adenosine deaminase activity. Since adenosine deaminase activity controls the amount of substrate available to xanthine oxidase, and the latter produces superoxide during turnover of its substrates, it is proposed that the purine salvage pathway is an important source of the superoxide requirement of macrophages. It is further proposed that this may be the basis, at least in part, for the mechanism of the association of immunodeficiency with adenosine deaminase deficiency.

Adenosine Deaminase↗
PubMed1980

Transient stimulatory adenosine deaminase activity in peripheral lymphocyte lysates from a case of T-cell lymphoma.

A fourteen-year old female presented with a mediastinal mass and pleural effusion. A diagnosis of a poorly differentiated lymphocytic lymphoma was made from a lymph node biopsy. Fluid from a pleural tap contained numerous lymphoblasts; 91.5% of these lymphoblasts had a thymus leukemic antigen. At presentation, although morphologically normal, no adenosine deaminase (ADA) activity could be demonstrated in her peripheral blood lymphocytes. Lysates of her lymphocytes mixed with lysates of lymphocytes with known ADA activity resulted in ADA activity that was greater than expected. With disappearance of tumor following the institution of therapy, ADA activity appeared in her lymphocytes and the above phenomenon disappeared.

Adenosine Deaminase↗
PubMed1979

Adenosine deaminase activity in a transplantable murine renal adenocarcinoma.

Adenosine deaminase (ADA) activity was studied in tumor tissue, spleen, and bone marrow of animals bearing a transplantable murine renal carcinoma. Tumor tissue and splenic ADA specific activities were elevated in these animals when compared to controls although splenic specific activity subsequently declined with increasing tumor burden. Marrow ADA specific activity was the same in tumor bearing animals as in controls regardless of variations in tumor size. Studies of this enzyme may offer insight into salvage pathways of purine biosynthesis thereby suggesting exploitable targets for chemotherapy.

Adenocarcinoma↗
PubMed1978

Adenosine deaminase activity in patients with carcinoma of the bladder.

Adenosine deaminase is an important enzyme in purine metabolism, and patients with abnormal lymphocyte and erythrocyte adenosine deaminase levels have been shown to have impaired immune competence. Since immune factors have been shown to be important in patients with transitional cell carcinoma of the bladder we studied adenosine deaminase activity in the hemic cells of 48 patients with this tumor. Lymphocyte adenosine deaminase levels were elevated in patients with transitional cell carcinoma and correlated with stage, activity, clinical course and tumor resection but not with tumor grade. Erythrocyte adenosine deaminase levels also were elevated in patients with transitional cell carcinoma but did not correlate with other disease parameters. Lymphocyte adenosine deaminase activity in patients with transitional cell carcinoma may be a sensitive indicator of disease activity and further studies may provide insight into the host-tumor relationship at the enzyme level.

Adenosine Deaminase↗
PubMed1978

Differences in purine metabolizing enzyme activities in human leukemia T-cell, B-cell and null cell lines.

Clear metabolic differences between T- and B-cells were demonstrated. Both adenosine deaminase (ADA) and nucleoside phosphorylase (NP) activities increased during logarithmic growth and then decreased in T-cells, but remained essentially constant during the growth cycle of B-cells. When these enzyme activities were examined in a number of T-cell, B-cell, and null cell lines, ADA activity was clearly higher in T-cells as compared to all others. With NP, the opposite appeared to be true, although the differences were much smaller and not statistically significant in all instances. No clear differences were found in the isoenzyme distributions of both enzymes in the various cell types.

Adenosine Deaminase↗
PubMed1978

Studies of lymphocyte adenosine deaminase activity in patients with renal and transitional cell carcinoma.

Adenosine deaminase (ADA) is a critical enzyme in purine metabolism and lymphocyte ADA activity is specifically related to immunocompetence in man. Since immunologic factors are relevant in patients with renal and transitional cell carcinoma, we studied lymphocyte ADA activity in these patients. In renal adenocarcinoma patients lymphocyte ADA activity was reduced. Such reductions were most marked in low-as compared to high-stage lesions. Nephrectomy resulted in a rise and disease progression in a decline in ADA activity. In contrast, bladder, carcinoma patients showed elevated lymphocyte ADA activity most marked in high-stage lesions. Disease progression was associated with a rise and tumor resection with a decline in lymphocyte ADA activity. Discordance in patterns of lymphocyte ADA activity when patients with renal and transitional cell carcinoma are compared suggests unique host-tumor interactions at the enzyme level. Studies of ADA may offer insight into molecular aspects of immune mechanisms.

Adenocarcinoma↗
PubMed1977

Adenosine deaminase activity in patients with renal adenocarcinoma.

Erythrocyte and lymphocyte adenosine deaminase (ADA) levels were studied in 31 patients with renal cell carcinoma (RCC). Decreased lymphocyte ADA levels occurred in patients with RCC. Erythrocyte ADA levels were reduced only in blood type B and O patients. Nephrectomy resulted in a rise in lymphocyte and erythrocyte ADA levels. Progression of clinical disease was associated with a fall in lymphocyte ADA values in all patients and with a rise in erythrocyte levels only in blood type A patients. Our results suggest that changes in erythrocyte and lymphocyte ADA levels in RCC patients are acquired and may offer insight into host-tumor interactions.

ABO Blood-Group System↗
PubMed1977

Synergism between the antiproliferative activities of arabinosyladenine and N6-benzyladenosine.

N6-Benzyladenosine is a competitive inhibitor of adenosine deaminase from L-1210 cells in axenic culture as well as a potent antiproliferative agent in vitro and in vivo. Potentiation of the growth inhibitory activity of 9-beta-D-arabinosyladenine (ara-A) was observed in the L-1210 system with maximum synergism with a mixture of 16 micron ara-A and 10 micron benzyladenosine. Kinetic studies with L-1210 cell lysates showed values for Km of 0.25 mM ara-A and Ki of 0.23 mM benzyladenosine. It is suggested that ara-A and benzyladenosine in suitable combination may be expected to demonstrate enhanced clinical chemotherapeutic effectiveness.

Adenosine↗
PubMed1976

Cosolvent-buffer mixtures as models for the cytoplasmic mileu: the enzymology of adenosine aminohydrolase.

Adenosine aminohydrolase from calf intestinal mucosa is sensitive to changes in its environment produced by small mole fractions of dimethylsulfoxide (DMSO). At a mole fraction of 0.1 where the dielectric constant is lowered from that of 78 of neat water to about 76.5, Vmax was reduced by 65% and affinity for substrate (adenosine) and the two competitive inhibitors, insine and N6-benzyladenosine, was decreased markedly. However, this decreased affinity was such that Ki/Km remained virtually constant for both inhibitors. DMSO itself showed the kinetics of a mixed inhibitor with Ki decreasing with increasing mole fraction. This cosolvent also decreased the heat stability of the enzyme which suggests that enzyme conformation is altered by DMSO. Comparison of data in the presence of DMSO with previously obtained data with dioxane shows that heat stability as well as Vmax, at a given value of dielectric constant, is independent of the amount or nature of cosolvent used to achieve that dielectric constant. However, cosolvent induced changes in Ki indicate that colligative as well as dielectric constant effects contribute to the observed changes in kinetic behavior. These experiments may be considered as models for the behavior of enzymes in the medium of lowered dielectric constant expected in the vicinity of cytoplasmic membranes. The results indicate that in such an environment, adenosine aminohydrolase would be expected to be less efficient a catalyst, but equally susceptible to product inhibition, as compared to media of dielectric constant approaching that of water.

Adenosine Deaminase↗
PubMed1976

Serum ribonuclease in patients with lung carcinoma.

Fifty-one previously untreated cases of lung carcinoma and 7 normal healthy controls were evaluated with respect to serum ribonuclease (S-RNase) levels. Cellular immunity was tested in 22 of these 51 cases by leukocyte migration inhibition test (MIT) using extract of culture cell line of lung carcinoma. S-RNase levels in lung carcinomas were significantly elevated. There appeared to be no difference in S-RNase levels by histological classification. More striking was high S-RNase level in disseminated versus localized cases. MIT results indicated impairment of cellular immunity in those cases of more elevated S-RNase. S-RNase may be implicated in blocking phenomenon associated with neoplastic disease.

Adenocarcinoma↗
PubMed1976

Synthesis and biological activities of some N4-substituted 4-aminopyrazolo(3,4-d)pyrimidines.

Syntheses and biological activities of 26 N4-substituted 4-aminopyrazolo[3,4-d]pyrimidines as analogs of naturally occurring modified nucleic acid bases, N-(purin-6-ylcarbamoyl)-L-threonine and N6-(delta2-isopentenyl)adenine, are described. 4-Aminopyrazolo[3,4-d]pyrimidine was converted into the desired intermediate, ethyl pyrazolo[3,4-d]pyrimidine-4-carbamate (2). 4-Ureidopyrazolo[3,4-d]pyrimidines (6-26) were prepared by displacement of the ethoxy group of the carbamate 2 by amino acids and a variety of amines and by a reaction of 4-aminopyrazolo[3,4-d]pyrimidine (1) with isocyanates. N4-Alkylaminopyrazolo[3,4-d]pyrimidines were generally prepared by displacement of the chlorine from 4-chloropyrazolo[3,4-d]pyrimidine with various amines. Several analogs exhibited moderate to very good growth inhibitory activities against cultured L1210 leukemia and 6410 human leukemic myeloblasts.

Animals↗
PubMed1976

Adenosine aminohydrolase from human spleen: partial purification and some kinetic properties.

Adenosine aminohydrolase from human spleen was purified 120 fold. In pH 7.3 phosphate buffer at 37 degrees, this enzyme preparation deaminated adenosine and arabinosyladenine (ara-A) with apparent values for the Michaelis constant of 40 muM and 90 muM respectively. The products of both deamination reactions, i.e., inosine and arabinosylhypoxanthine, were competitive inhibitors with Ki equal to 710 muM and 60 muM, respectively. N6-benzyladenosine and 2'-deoxy-N6-benzyladenosine were competitive inhibitors. The former was better able to inhibit ara-A than adenosine deamination, while the latter was equivalent in inhibiting deamination of these two substrates. Evidence for a naturally occurring adenosine aminohydrolase inhibitor in spleen was presented. It is suggested that benzyladenosine and deoxybenzyladenosine might potentiate ara-A chemotherapy of neoplasms and metastates in the spleen and other hemic cells.

Adenosine↗
PubMed1976

Adenosine deaminase levels in blood type A patients with metastatic tumor.

A lack of adenosine deaminase activity has been associated with severe combined immunodeficiency and decreased enzyme activity observed in acute lymphocytic leukemia. We have measured enzyme activity in lymphocytes, red blood cells, and plasma of patients with a variety of metastatic tumors. Patients with tumor had a significantly lower erythrocyte adenosine deaminase activity (p less than 0.025) and statistically higher enzyme activity in their lymphocytes (p less than 0.010) when compared with control plasmaphoresis donors. Interestingly, blood type A tumor patients showed a significant decrease in their erythrocyte enzyme concentration compared with blood group A controls (p less than 0.001) as well as a collective group of type B and O tumor patients (p less than 0.001). Type A patient lymphocyte adenosine deaminase activity was not increased and was not statistically different from control group A donors. Tumor patients with blood groups B and O considered collectively had a statistically significant increase in their lymphocyte enzyme concentration compared with group B and O controls (p less than 0.001).

ABO Blood-Group System↗