Arrest of in vivo growth of a solid Leydig cell tumor by prolonged inhibition of mitochondrial protein synthesis

Oxytetracycline was given by means of chronic i.v. infusion, in amounts which impair specifically mitochondrial protein synthesis, to Wistar rats carrying a solid Leydig cell tumor. The prolonged inhibition of mitochondrial protein synthesis finally results in proliferation arrest of the s.c. growing tumor. As long as the tumor is growing, the energy-generating capacity of the mitochondrial becomes diluted, until it is reduced to a critical level, which results in growth arrest. This cytostatic effect is found after treatment for 8 to 12 days. During this period, the tumor volume increases to an extent comparable to 2 to 3 tumor cell divisions. The proliferation arrest found is, at least after treatment for 3 weeks, reversible. Withdrawal of oxytetracycline results in continuation of tumor growth after a latent period of about 5 days. The data confirm previous observations made in experimental systems about the usefulness of mitochondrial protein synthesis as target for cancer chemotherapy. They support, moreover, the explanation given for the marked prolongation of survival time found in tetracycline-treated patients with a squamous cell carcinoma of the larynx-pharynx. If antineoplastic therapy, based on inhibition of mitochondrial protein synthesis, is considered, the tetracyclines should be the drugs of choice, because their toxic side effects are minimal at dosages which cause tumor proliferation arrest.     

Feasibility of high‐density electrophysiological study using multiple‐electrode array in isolated small animal atria

1. High‐density cardiac electrophysiological study (EPS) of small animal atria has been limited to optical mapping techniques, which require complex and expensive equipment setup. We aim to evaluate the feasibility of carrying out EPS in isolated atrial tissues using a custom made high‐density multiple‐electrode array (MEA). 2. Isolated rat atrial preparations were studied. The MEA (4 × 5 mm) consisted of 90 silver chloride coated electrodes (0.1 mm diameter, 0.5 mm pitch) and was connected to a conventional EP system yielding 80 bipolar signals. Atrial tissues were placed over the MEA in a dish bubbled with 100% oxygen and superfused with modified HEPES solution at pH 7.35 and 37°C. Then, 1 mmol of 2,3‐butanedione monoxime was added to suppress motion artifacts from muscle contractions. Custom plaque analysis software was used for offline conduction analysis. 3. Isolated atrial tissues showed good viability of > 30 min, allowing ample time for complete EPS. High quality electrograms with excellent signal to noise ratio were obtained. All electrophysiological parameters showed good reproducibility: effective refractory period, conduction velocity and heterogeneity index. Tachycardia was also inducible in these normal atria. 4. The present study shows the feasibility of performing high‐density EPS of small isolated atrial tissues with a conventional electrode‐based technique. The MEA system is compatible with standard electrophysiology recording systems and provides a novel, inexpensive option for detailed EPS in small animal models. In particular, it presents new research avenues to further explore the mechanisms of atrial arrhythmias in various transgenic and knockout rodent models.     

IgMs produced by two acquired immune deficiency syndrome lymphoma cell lines: Ig binding specificity and VH-gene putative somatic mutation analysis [published erratum appears in Blood 1994 Aug 1;84(3):995]

Two B-cell lines, 2F7 and 10C9, were established by single cell cloning from biopsies obtained from two acquired immune deficiency syndrome patients with Burkitt's lymphoma. Representation of the original tumors was verified by demonstration of (1) identical biallelic rearrangement of Ig genes for 2F7 and (2) shared idiotype for 10C9. Both cell lines displayed cell-surface Ig and secreted Ig (IgM lambda for 2F7, IgM kappa for 10C9). IgMs from both cell lines immunoprecipitated actin; in addition, 2F7 IgM lambda immunoprecipitated recombinant human immunodeficiency virus type 1 (HIV-1) gp 160. 2F7 IgM lambda did not react with other autoantigens (double-stranded and single-stranded DNA, actin, bovine serum albumin, IgG), whereas 10C9 IgM kappa reacted with human IgG. The 2F7 IgM heavy-chain variable region (VH) showed a 95% nucleotide homology with a previously sequenced VHIII germline gene, hv3019b9, whereas the 10C9 IgM VH showed a 95% homology with a previously sequenced VHIV germline gene, VH4.21. Use of minimally modified VH genes and demonstration of reactivity with chronically present antigens (ie, actin, HIV-1 gp 160, or human IgG) suggests that B cells in HIV-1-infected individuals proliferating in response to chronic antigenic stimulation may be at increased risk for lymphomagenesis.     

Correlation of drug sensitivity in vitro with clinical responses in childhood acute myeloid leukemia

Clonogenic cells from 41 children with newly diagnosed acute myeloid leukemia (AML) were tested in vitro for their sensitivity to cytarabine (Ara-C) and daunorubicin (DNR). The findings were then compared with the patients' responses to induction chemotherapy that uniformly included Ara-C and DNR. Light-density marrow cells were incubated with either or both drugs for one hour and cultured over leukocyte feeder layers; clusters and colonies were scored on days 7, 10, and 14. Only the percentage of cell kill in the presence of 1.8 mumol/L DNR was significantly associated with responses to induction therapy: median of 45% (range, 0% to 98%) for patients achieving complete remission v 16% (range, 4% to 23%) for nonresponders (P = .007). The relationship between clonogenic cell kill less than or equal to 23% and clinical responses was striking. Of the 11 evaluable patients with in vitro findings in this category, ten either failed induction therapy or relapsed within 1 year after attaining remission. Kaplan-Meier analysis of relapse-free survival times indicated longer durations of remission for patients whose blast cells showed increased sensitivity in vitro to Ara-C alone, DNR alone, or a combination of the two agents. Seven of 11 patients with cell kills of greater than or equal to 49% in the presence of 1.25 mumol/L Ara-C remain free of leukemia, compared with only one of 12 whose cells were less sensitive to the drug (P = .006). We conclude that the in vitro sensitivity of clonogenic leukemic progenitors to DNR and Ara-C correlates with treatment outcome in children with newly diagnosed AML.     

Expression and function of receptors for stem cell factor and erythropoietin during lineage commitment of human hematopoietic progenitor cells

The aim of the present study was to determine whether stem cell factor (SCF) and erythropoietin (EPO) act differently on defined subsets of progenitor cells, and if potential differences correlate with the receptor density on each subset. To investigate this possibility directly, we optimized conditions for the identification and purification of homogeneous progenitor cell subpopulations from human bone marrow. Populations containing 40% and 44% colony forming cells (CFCs) with 99% and 95% purity for the granulomonocytic and erythroid lineage, respectively, were sorted on the basis of differential expression of CD34, CD64, and CD71. In addition, a population containing 67% CFCs, of which 29-43% were CFU-MIX, was sorted from CD34hi CD38loCD50+ cells. Purified progenitor cell subsets were compared directly for responsiveness to SCF and EPO using a short-term proliferation assay. Expression of the receptors for SCF and EPO were then examined on each subset using a flow cytometer modified for high- sensitivity fluorescence measurements. The results show that EPO induces extensive proliferation of erythroid progenitor cells, but has no effect on the proliferation or survival of primitive or granulomonocytic progenitors, even when used in combination with other cytokines. The majority of erythroid progenitor cells furthermore stained positively with anti-EPO receptor (EPO-R) monoclonal antibodies, whereas other progenitor cells were negative. SCF alone induced extensive proliferation of erythroid progenitor cells, and had a stronger synergistic effect on primitive than on granulo-monocytic progenitors. In spite of these differences in SCF activity, there were no significant differences in SCF-R expression between the progenitor subsets. These results suggest that the selective action of EPO on erythropoiesis is determined by lineage-restricted receptor expression, whereas there are additional cell-type specific factors that influence progenitor cell responses to SCF.     

Active immunization of murine allogeneic bone marrow transplant donors with B-cell tumor-derived idiotype: a strategy for enhancing the specific antitumor effect of marrow grafts

Persistence of the underlying malignancy remains the major obstacle limiting the success of high-dose chemoradiotherapy with allogeneic bone marrow transplantation (BMT) for lymphomas and multiple myeloma. We used the C3H 38C13 murine B-cell lymphoma, which expresses and secretes clonally derived Ig, the idiotype of which can serve as a tumor-specific antigen, to test the principle of transfer of tumor idiotype-specific immunity with BM. BALB/c marrow donors were twice immunized with 38C13-derived Ig, or with an isotype-matched control Ig, conjugated to keyhole limpet hemocyanin. Lethally irradiated C3H recipients reconstituted with marrow from idiotype immune, but not nonspecifically immune, donors demonstrated protection against subsequent lethal tumor challenge. The immunoprotective effect of immune allogeneic marrow was abrogated by T-cell depletion of the marrow graft before infusion. Low levels of serum anti-idiotypic antibody remained unaltered in recipients of T-cell-depleted immune marrow, consistent with a primary role for T-cell immunity in the cellular mechanism of this phenomenon. A modest therapeutic effect of immune allogeneic marrow was observed against 10 day, 1 cm established subcutaneous tumors, but only in combination with a booster immunization of the recipient post-BMT. These results provide the rationale for a novel strategy for enhancing the specific antitumor effect of allogeneic marrow grafts.     

Sustained, retransplantable, multilineage engraftment of highly purified adult human bone marrow stem cells in vivo

Data from many laboratory and clinical investigations indicate that CD34+ cells comprise approximately 1% of human bone marrow (BM) mononuclear cells, including the progenitor cells of all the lymphohematopoietic lineages and lymphohematopoietic stem cells (stem cells). Because stem cells are an important but rare cell type in the CD34+ cell population, investigators have subdivided the CD34+ cell population to further enrich stem cells. The CD34+/CD38- cell subset comprises less than 10% of human CD34+ adult BM cells (equivalent to < 0.1% of marrow mononuclear cells), lacks lineage (lin) antigens, contains cells with in vitro replating capacity, and is predicted to be highly enriched for stem cells. The present investigation tested whether the CD34+/CD38- subset of adult human marrow generates human hematopoiesis after transfer to preimmune fetal sheep. CD34+/ CD38- cells purified from marrow using immunomagnetic microspheres or fluorescence-activated cell sorting generated easily detectable, long- term, multilineage human hematopoiesis in the human-fetal sheep in vivo model. In contrast, transfer of CD34+/CD38+ cells to preimmune fetal sheep generated only short-term human hematopoiesis, possibly suggesting that the CD34+/CD38+ cell population contains relatively early multipotent hematopoletic progenitor cells, but not stem cells. This work extends the prior in vitro evidence that the earliest cells in fetal and adult human marrow lack CD38 expression. In summary, the CD34+/ CD38- cell population has a high capacity for long-term multilineage hematopoietic engraftment, suggesting the presence of stem cells in this minor adult human marrow cell subset.     

Evaluation of previous management against a developed clinical pathway for chronic rhinosinusitis with nasal polyposis in Universiti Kebangsaan Malaysia Medical Center

The study aims to evaluate previous management of CRSwNP patients in Universiti Kebangsaan Malaysia Medical Center (UKMMC) against a developed CP.Chronic rhinosinusitis with nasal polyposis (CRSwNP) has high economic burden and impacts patient''s quality of life. Implementation of clinical pathway (CP) can standardize care while optimizing resources.Analytical cross-sectionalThis study utilized medical records of 103 CRSwNP patients at UKMMC otorhinolaryngology clinic from 2010 to 2015. Patients were divided into groups who underwent or did not undergo surgery. Information was obtained regarding sociodemographic, follow-ups, pharmaceutical regimes, and treatment cost. Cost analysis was done using top-down analysis and activity-based costing and CP was formulated. Cost was calculated using year 2020 rates to adjust for inflation. (United States Dollars [USD]1 = Ringgit Malaysia [RM] 4.2015)Study showed non-CP patients were undertreated compared to CP. This affects clinical outcomes as optimal treatment demanded by CP was not achieved. Total cost for non-CP, non-surgery patients were lower (USD660) compared to CP (USD780) due to under treatment and shorter follow-ups. Meanwhile, total cost for non-CP surgery patients were higher (USD3600) compared to CP (USD2706) due to longer visit durations and hospital stays. Non-CP surgery group underwent lengthy follow-up duration (20.7 months) prior to operation compared to 12 months expected in CP.Study showed non-CP patients were undertreated compared to CP. We identified aspects which resulted in resource wastage and unnecessary burden to our healthcare system. This study enables development of a written CP by fine-tuning various aspects of CP which could be applied to our future practice.