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Biomedical subjects

D Martinez

Publications and source records attributed to D Martinez.

At least 181 records · Page 10Linked to original sources
PubMed1975

Immune mechanisms in leukemia: suppression of cellular immunity by starvation.

The effects of starvation on the cellular immune response of C58/Wm mice to syngeneic malignant lymphoid cells (1b cells) were studied. Mice were starved 1-3 days before or after immunization. The capacity of starved animals to survive immunization was used to quantify immunosuppression. When starvation bracketed immunization by -1 to +1 days, only 2 of 23 mice survived primary immunization, compared with 100% survival for nonstarved controls. A 2-day period of starvation +1 to +7 days after primary immunization reduced survival about 30%. For a test of the effect of starvation on the secondary immune response, mice were immunized, starved 2 days, and then challenged with viable lb cells. When mice were starved from -3 to +1 days before or after challenge, there was a 25-45% decrease in survival. Starvation caused a disproportionate depletion of lymphoid tissue elements. The proportional loss in the weight of the spleen and thymus was essentially twice as great as the loss in total body weight. The peripheral blood leukocyte count was reduced by about 20% when mice were starved 1 day and by approximately 50% when they were starved 2 days. When mice were starved 1-2 days, the differential leukocyte count did not shift and there was no significant change in the number of blood erythrocytes or in the hematocrit. Starvation for 2 days caused a 65-70% reduction in the number of viable mononuclear spleen cells. Starvation for 3 days caused about 90% reduction. Adoptive cell transfer experiments showed that the immunocompetence of individual spleen immunocytes was not reduced by starvation.

Animals↗
PubMed1975

Immune mechanisms in leukemia: evaluation of immunocompetent cell populations.

Dose-response curves of the cellular immune response of C58/wm mice to syngeneic line Ib malignant lymphoid cells (Ib cells) were computer analyzed by the PROBT subroutine in the IBM Scientific Subroutine Package. An analysis of the relative immunogenicity of various admixtures of x-irradiated (XIb) and viable Ib cells (VIb) after i.p. injection showed that the ratio had to be approximately 100:1 to be immunogenic. Viable Ib cells contained in immunogenic mixtures multiplied in vivo at a logarithmic rate up to 5 or 6 days but were eliminated immunologically by 8 or 9 days. Adoptive cell transfer techniques were used to quantify the protective effect of immune spleen cells (ISC). Essentially a constant dose of ISC (10-6.4) protected mice against a challenge dose of 10-2 to 10-5 VIb cells; more than 10-5 VIb cells were lethal. Two techniques were used to quantify immunity even though mice ultimately died of transplanted leukemia, viz., mean survival time (MST) with a fixed challenge dose of VI b cells, or MST with a fixed time for death. The sensitivity and statistical limitations of these assays are presented. To amplify the sensitivity of assays for adoptive cellular immunity a technique of antigenic stimulation was used, viz., 1 day after x-irradiated mice (600 R) received an i.p. injection of normal or immune spleen, bone marrow or thymic cells they received an i.p. injection of XIb cells containing an admixture of VIb cells. The technique amplified the sensitivity of ISC transfer tests approximately 100-fold and made it possible to detect protective effects of bone marrow and thymic cell populations.

Animals↗
PubMed1975

Immune mechanisms in leukemia: suppression of cellular immunity by drugs and x-irradiation.

The relative suppressive effects of x-irradiation (XR), cyclophosphamide (CY), prednisolone (PRD), and methotrexate (MTX) on the primary and secondary cellular immune response of C58/wm mice to syngeneic line Ib transplantable leukemia (Ib cells) were quantified. An LD10 dose of each agent was used for immunosuppression. XR, CY, and PRD were markedly suppressive for the primary immune response if given 24 hr before mice were immunized to Ib cells but less immunosuppressive if given 24 hr later. MTX was only slightly immunosuppressive XR, CY, and PRD also suppressed the secondary immune response if given before but not after antigen. The immunosuppressive effect of these agents was evaluated by defining their median immunosuppressive dose or the median time in days required for mice to recover from graded doses of each immunosuppressive agent. For example, the median recovery time from an LD10 of XR, CY, and PRD was 29.3, 19.7, and 3.7 days, respectively. Immunologic competence remaining after XR or drug treatment was quantified in terms of the LD50 dose of Ib cells required to kill recipient mice. For XR, CY, PRD, and MTX it was 10(6.16), 10(2.15), 10(6.90) and greater than 10(7.0) viable Ib cells, respectively. The overall results provided evidence that the primary and secondary cellular immune responses to a weak syngeneic tumor antigen were resistant to immunosuppression once they were initiated. There was a good correlation between the relative immunosuppressive effect of the test agents and the amount that they reduced the number of immune spleen cells. The agents also impaired the immunocompetence of individual spleen cells. Mechanisms by which XR or drugs might exert their immunosuppressive effects were discussed.

Animals↗
PubMed1973

Selective autocytotoxicity in a model system of Escherichia coli K-12 recombinants.

Autocytotoxicity was shown by Lac(+) recombinant strains of Escherichia coli K-12 when their growth was inhibited in media containing o-nitrophenyl-beta-d-galactopyranoside. Lac(-) strains without lactose permease or beta-galactosidase activity grew well. Selective autocytotoxicity was shown by simultaneous inhibition of Lac(+) cells and multiplication of Lac(-) cells grown together in this medium.

Culture Media↗
PubMed1969

Nuclear magnetic resonance studies of sodium ions in isolated frog muscle and liver.

Nuclear magnetic resonance (NMR) was used to determine Na(+) complexing in muscle and liver (at 23 degrees C) from bullfrogs (Rana catesbeiana) and to study the influence of temperature on Na(+) complexing in muscle from leopard frogs (Rana pipiens). The Na(+) complexed in muscle and liver was found to be 36.6 +/- 4.6% and 66.1 +/- 3.5% respectively. A temperature decrease from +34 degrees C to -2 degrees C results in a 20% decrease in the mobility of the free Na(+) in the fresh muscle. This 20% decrease in mobility results in about 50% of the free Na(+) at 34 degrees C being complexed at the lower temperature.

Animals↗
PubMedDate not supplied

Psychotherapy refusers.

A systematic review of 414 terminated cases on a semiprivate psychotherapy service revealed that 16.7% of patients never began therapy despite being accepted after an extensive and lengthy screening process. This is lower than in previous studies. Except for ethnicity, comparison between the refusers and acceptors of 42 variables failed to replicate the correlations found in previous studies. In our sample, psychotherapy refusers were characterized by (1) having less family psychiatric history, (2) being more likely to elaborate their problems, (3) having less alcohol abuse history, (4) being less likely to be offered long-term individual therapy, and (5) having waited less time for their screening appointment. Such variables as age, gender, diagnosis, severity, income, and education were all nonsignificant. Although we offer some hypotheses for our significant correlations, we suspect that the interaction with the screener is more important than patient variables in determining acceptance of psychotherapy.

Adolescent↗
PubMedDate not supplied

Diagnostic and prognostic value of the determination of the aminopropeptide of type III procollagen in patients with primary liver cancer.

Hepatic fibroplasia seems to play an important role in the course of primary liver cancer (PLC) since, for instance, encapsulated and fibrolamellar hepatocellular carcinomas show a definitely better prognosis. In this study, serum procollagen III amino-terminal peptide (PIIIP) levels, which reflect synthesis and release of procollagen type III, were measured with the aim of assessing hepatic fibrogenesis in PLC patients and determining whether serum PIIIP levels play a diagnostic or prognostic role in PLC. Twenty-five patients with PLC, 74 patients with cirrhosis and 38 healthy volunteers were studied. Serum PIIIP levels were determined by a radioimmunoassay (RIA) method. In PLC patients PIIIP serum levels were significantly higher than those of controls and cirrhotic patients (P less than 0.001 and P less than 0.01 respectively) but an analysis of individual values showed an important overlap between PLC and cirrhosis. No correlation was found between serum PIIIP levels and tumour histology, presence or absence of cirrhosis, Child status, possible aetiology of the disease, indices of hepatocellular inflammation, cholestasis and synthesis, or tumour markers. On the contrary, serum PIIIP levels correlated with tumour gross pattern (z = 3, P less than 0.001) and, inversely, with survival (r = 0.659, P less than 0.01), patients with serum PIIIP over 25 ng/mL showing a significantly worse prognosis. These data confirm that hepatic fibroplasia plays an important, but not yet fully understood, role in the course of PLC. From the clinical point of view, PIIIP determination does not add to the differential diagnosis between PLC and cirrhosis but helps to identify patients with larger liver replacements and worse prognoses.

Biomarkers, Tumor↗
PubMedDate not supplied

Separation of cannabinoids.

The three main cannabinoids--cannabidiol (CBD), tetrahydrocannabinol (THC) and cannabinol (CBN)-can be isolated from purified extract of cannabis by preparative gas chromatography in satisfactory amounts and with a degree of purity similar to that of the sample substances provided by the United Nations Narcotics Laboratory.

Cannabidiol↗
PubMedDate not supplied

[Narcolepsy, an epidemic?].

Narcolepsy, was first described in 1880, is a chronic, disabling disease characterized by excessive daytime sleepiness and abnormal REM manifestations. It is estimated that, in Brazil, 15,000 to 150,000 cases may exist, but is was only since the first sleep laboratories were installed in the country that the disease began to be recognized. It created a sudden increase in the number of diagnosis which actually simulates an epidemics in the medical records. The existence of a sleep laboratory, however, is not necessary for the diagnosis of the disease. An informed clinician can identify it during the interview. The goal of this paper is to inform about the clinical, diagnostic, and therapeutic aspects of the disease through the report of four selected cases.

Adult↗