Lack Of Growth Factor Research Articles

Latent stem cell-stimulating radially aligned electrospun nanofibrous patches for chronic tympanic membrane perforation therapy

Chronic tympanic membrane (TM) perforation is a tubotympanic disease caused by either traumatic injury or inflammation. A recent study demonstrated significant progress in promoting the regeneration of chronic TM perforations through the application of nanofibers with radially aligned nanostructures and controlled release of growth factors. However, radially aligned nanostructures with stem cell-stimulating factors have never been used. In this study, insulin-like growth factor binding factor 2 (IGFBP2)-incorporated radially aligned nanofibrous patches (IRA-NFPs) were developed and applied to regenerate chronic TM perforations. The IRA-NFPs were prepared by electrospinning 8 wt% polycaprolactone in trifluoroethanol and acetic acid (9:1). Random nanofibers (RFs) and aligned nanofibers (AFs) were successfully fabricated using a flat plate and a custom-designed circular collector, respectively. The presence of IGFBP2 was confirmed via Fourier transform infrared spectroscopy and the release of IGFBP2 was sustained for up to 20 days. In vitro studies revealed enhanced cellular proliferation and migration on AFs compared to RFs, and the incorporation of IGFBP2 further promoted these effects. Quantitative real-time PCR revealed mRNA downregulation, correlating with accelerated migration and increased cell confluency. In vivo studies showed IGFBP2-loaded RF and AF patches increased regeneration success rates by 1.59-fold and 2.23-fold, respectively, while also reducing healing time by 2.5-fold compared to the control. Furthermore, IGFBP2-incorporated AFs demonstrated superior efficacy in healing larger perforations with enhanced histological similarity to native TMs. This study, combining stem cell stimulating factors and aligned nanostructures, proposes a novel approach potentially replacing conventional surgical methods for chronic TM perforation regeneration. Statement of significanceChronic otitis media (COM) affects approximately 200 million people worldwide due to inflammation, inadequate blood supply, and lack of growth factors. Current surgical treatments have limitations like high costs and anesthetic risks. Recent research explored the use of nanofibers with radially aligned nanostructures and controlled release of growth factors to treat chronic tympanic membrane (TM) perforations. In this study, insulin-like growth factor binding protein 2 (IGFBP2)-incorporated radially aligned nanofibrous patches (IRA-NFPs) were developed and applied to regenerate chronic TM perforations. We assessed their properties and efficacy through in vitro and in vivo studies. IRA-NFPs showed promising healing capabilities with chronic TM perforation models. This innovative approach has the potential to improve COM management, reduce surgery costs, and enhance patient safety.

Pediatric endodontic considerations in the application of regenerative therapy for immature permanent teeth: a review article

For adult teeth with necrosis or apical periodontitis, regenerative endodontics provides a useful alternative to standard endodontic treatment. This review focuses on the pediatric endodontic considerations in the application of regenerative therapy for immature permanent teeth. A thorough literature search was conducted in the MEDLINE database using the keywords "pediatric, regenerative, therapy, endodontics, immature, permanent, and teeth" to find relevant publications published between 2017 and 2024. Additionally, Google Scholar was used to find and access pertinent scientific publications using the appropriate search terms. Various inclusion criteria were applied to select the articles for review. The selected articles were published between 2020 and 2024 and included discussions on several specific elements. Topics covered include the criteria for case selection for regenerative endodontics. Overall, the existing evidence indicates that using regenerative endodontic techniques to treat adult permanent teeth with apical periodontitis or necrosis may successfully lead to the resolution of apical translucencies and the absence of clinical signs and symptoms. With slight modifications to the clinical procedure, regenerative dentistry methods can be effectively applied to specific cases, such as those involving a small apical foramen, decreased blood supply, and a lack of growth factors. However, additional research is required to determine the optimal conditions for achieving successful treatment outcomes.

Role of Burns-Manual in Burns Management

Electric burns are known for difficulty in healing and wound management. There is a lack of growth factors in these chronic wounds and needs to be supplemented with adjuvant therapy that allows for faster healing we have used the JIPMER burns manual to allow the management to be protocol based.

Repopulation of decellularised articular cartilage by laser-based matrix engraving.

BackgroundIn spite of advances in the treatment of cartilage defects using cell and scaffold-based therapeutic strategies, the long-term outcome is still not satisfying since clinical scores decline years after treatment. Scaffold materials currently used in clinical settings have shown limitations in providing suitable biomechanical properties and an authentic and protective environment for regenerative cells. To tackle this problem, we developed a scaffold material based on decellularised human articular cartilage.MethodsHuman articular cartilage matrix was engraved using a CO2 laser and treated for decellularisation and glycosaminoglycan removal. Characterisation of the resulting scaffold was performed via mechanical testing, DNA and GAG quantification and in vitro cultivation with adipose-derived stromal cells (ASC). Cell vitality, adhesion and chondrogenic differentiation were assessed. An ectopic, unloaded mouse model was used for the assessment of the in vivo performance of the scaffold in combination with ASC and human as well as bovine chondrocytes. The novel scaffold was compared to a commercial collagen type I/III scaffold.FindingsCrossed line engravings of the matrix allowed for a most regular and ubiquitous distribution of cells and chemical as well as enzymatic matrix treatment was performed to increase cell adhesion. The biomechanical characteristics of this novel scaffold that we term CartiScaff were found to be superior to those of commercially available materials. Neo-tissue was integrated excellently into the scaffold matrix and new collagen fibres were guided by the laser incisions towards a vertical alignment, a typical feature of native cartilage important for nutrition and biomechanics. In an ectopic, unloaded in vivo model, chondrocytes and mesenchymal stromal cells differentiated within the incisions despite the lack of growth factors and load, indicating a strong chondrogenic microenvironment within the scaffold incisions. Cells, most noticeably bone marrow-derived cells, were able to repopulate the empty chondrocyte lacunae inside the scaffold matrix.InterpretationDue to the better load-bearing, its chondrogenic effect and the ability to guide matrix-deposition, CartiScaff is a promising biomaterial to accelerate rehabilitation and to improve long term clinical success of cartilage defect treatment.FundingAustrian Research Promotion Agency FFG (“CartiScaff” #842455), Lorenz Böhler Fonds (16/13), City of Vienna Competence Team Project Signaltissue (MA23, #18-08)

Autophagy and the potential linkage with the human oral diseases

Autophagy is a cell survival mechanism that has a key role in both physiologic and pathologic conditions. In this cellular ‘clearance’ process, damaged organelles and macromolecules are transported to the lysosomes for degradation. With autophagy, a protection mechanism occurs in the cell under difficult conditions including oxidative stress and lack of growth factor. Paradoxically, in autophagy under some conditions, non-apoptotic cell death can be observed via a caspase-independent pathway. Recent, studies indicated that there is a strong correlation between the composition of the oral microbiota and the pathogenesis of oral diseases, and autophagy plays a crucial role in the development of this process. This review is focused on the molecular mechanism of autophagy and its relationship with human oral diseases. In this review, the importance of the autophagy mechanism in the maintenance of oral tissue health is emphasized. After examining the studies, we observed the importance of autophagy in response to a variety of oral diseases and aimed to present this awareness. Thus, a better understanding of autophagy will be the basis for developing new therapeutic strategies in the treatment of oral diseases.

Effective Healing of Leprosy Chronic Plantar Ulcers by Application of Human Amniotic Membrane Stem Cell Secretome Gel.

Background:Chronic plantar ulcers are common problems for leprosy patients with numb feet due to their prolonged healing time. Chronic plantar ulcers affect the quality of life of patients and can lead to more serious complications, such as disability and deformity, if not handled appropriately. Wound-care products in the market, however, give unsatisfactory results. One factor in the delayed healing of chronic plantar ulcers due to leprosy is the lack of growth factors and cytokines in the wound due to reduced blood supply. We speculated that application of human amniotic membrane stem cell (hAMSC) secretome, which contains growth factors and cytokines, could improve wound healing.Aim:To evaluate the effect of topical application of a hAMSC secretome gel on wound healing of chronic plantar ulcers due to leprosy.Materials and Methods:We recruited 11 patients after leprosy treatment with chronic plantar ulcers due to leprosy. hAMSC secretome gel was applied topically to ulcers every 3 days for up to 2 months. Ulcer size and possible side effects or complications from gel application were evaluated weekly.Results:The ulcers of 8 of 11 patients (72.7%) completely healed, the ulcers of 2 patients (18.2%) partially healed, and the ulcers of 1 patient (9.1%) persisted. No ulcers became worse.Conclusion:hAMSC secretome was found to be an efficacious and well-tolerated alternative therapy for chronic plantar ulcers due to leprosy.

Initial Steps in Mammalian Autophagosome Biogenesis.

During the last decade, autophagy has been pointed out as a central process in cellular homeostasis with the consequent implication in most cellular settings and human diseases pathology. At present, there is significant data available about molecular mechanisms that regulate autophagy. Nevertheless, autophagy pathway itself and its importance in different cellular aspects are still not completely clear. In this article, we are focused in four main aspects: (a) Induction of Autophagy: Autophagy is an evolutionarily conserved mechanism induced by nutrient starvation or lack of growth factors. In higher eukaryotes, autophagy is a cell response to stress which starts as a consequence of organelle damage, such as oxidative species and other stress conditions. (b) Initiation of Autophagy; The two major actors in this signaling process are mTOR and AMPK. These multitasking protein complexes are capable to summarize the whole environmental, nutritional, and energetic status of the cell and promote the autophagy induction by means of the ULK1-Complex, that is the first member in the autophagy initiation. (c) ULK1-Complex: This is a highly regulated complex responsible for the initiation of autophagosome formation. We review the post-transductional modifications of this complex, considering the targets of ULK1. (d)The mechanisms involved in autophagosome formation. In this section we discuss the main events that lead to the initial structures in autophagy. The BECN1-Complex with PI3K activity and the proper recognition of PI3P are one of these. Also, the transmembrane proteins, such as VMP1 and ATG9, are critically involved. The membrane origin and the cellular localization of autophagosome biogenesis will be also considered. Hence, in this article we present an overview of the current knowledge of the molecular mechanisms involved in the initial steps of mammalian cell autophagosome biogenesis.

Xeno-free autologous platelet rich plasma for chronic wound management – Case series

Abstract Background In chronic wounds, healing process gets halted in inflammatory phase owing to lack of growth factors (GF). The concept of exogenous delivery of such GF as platelet rich plasma (PRP)/fibrin (PRF) could be logical strategy for their management. We evaluated efficacy of single dose of non-activated PRP and self- polymerized platelet rich fibrin (PRF) in subjects with chronic wounds. Methods 35 Subjects with wounds of different depths and etiologies were administered with PRP or PRP + PRF and assessed with Bates-Jensen Wound Assessment Tool (BWAT). Results Majority of subjects in PRP group responded well and entered into regenerative zone. In PRP + PRF group, 36% subjects benefitted from this treatment. Conclusion Our study demonstrates that single dose of non-activated PRP is an efficacious treatment regime for chronic wounds. Further, it eliminates need for multiple doses due to continual release of growth factor over a long period of time, thus considerably reducing effective cost of procedure.

Targeting LC3 and Beclin-1 autophagy genes suppresses proliferation, survival, migration and invasion by inhibition of Cyclin-D1 and uPAR/Integrin β1/ Src signaling in triple negative breast cancer cells.

Autophagy is a catabolic process for degrading dysfunctional proteins and organelles, and closely associated with cancer cell survival under therapeutic, metabolic stress, hypoxia, starvation and lack of growth factors, contributing to resistance to therapies. However, the role of autophagy in breast cancer cells is not well understood. In the present study, we investigated the role of autophagy in highly aggressive and metastatic triple negative breast cancer (TNBC) and non-metastatic breast cancer cells and demonstrated that the knockdown of autophagy-related genes (LC3 and Beclin-1) inhibited autophagy and significantly suppressed cell proliferation, colony formation, migration/invasion and induced apoptosis in MDA-MB-231 and BT-549 TNBC cells. Knockdown of LC3 and Beclin-1 led to inhibition of multiple proto-oncogenic signaling pathways, including cyclin D1, uPAR/integrin-β1/Src, and PARP1. In conclusion, our study suggests that LC3 and Beclin-1 are required for cell proliferation, survival, migration and invasion, and may contribute to tumor growth and progression of highly aggressive and metastatic TNBC cells and therapeutic targeting of autophagy genes may be a potential therapeutic strategy for TNBC in breast cancer.

Abstract B06: EpCAM functions as a sensor that allows prostate cancer cells to become quiescent in response to lack of growth factors.

Abstract Introduction: Recent studies have shown that intra-tumor heterogeneity is the main cause of therapeutic resistance in cancer. Tumor tissue is composed of heterogeneous cellular populations with a hierarchical organization governed by stem/progenitor-like cells, also referred to as cancer stem-like cells (CSCs). Epithelial cell adhesion molecule (EpCAM), also known as CD326, is over-expressed ubiquitously in CSCs that originate from epithelial lesions. Prostate cancer stem-like cells highly express EpCAM. However, little is known about how EpCAM is involved in the ability of cells to adapt to micro-environmental changes in available growth factors, which is one of the essential biological phenotypes of CSCs. Methods: EpCAM-high and EpCAM-low subpopulations of cells were established from the prostate cancer cell line PC-3. Signal transduction in response to serum starvation, signaling pathways essential for tumorigenic potential in vivo, and the machinery of serum depletion-induced dormancy and plasticity were analyzed by immunoblot, quantitative RT-PCR, flow cytometry, and immunohistochemical staining. Results: EpCAM-high and EpCAM-low PC-3 subpopulations showed markedly different responses to serum starvation. EpCAM expression was positively correlated with activation of the mammalian target of rapamycin (mTOR) and epithelial growth factor receptor (EGFR) signaling pathways. Contrary to accepted wisdom, AMP-activated protein kinase (AMPK) was gradually de-activated in EpCAM-low PC-3 cells in the absence of serum. In addition, the Spearman's rank correlation between EpCAM and LAT1 in parental, EpCAM-high, and EpCAM-low PC-3 cells was very high (0.859), which implied that the expression of EpCAM correlates with the potential of leucine uptake. Both EpCAM-high and EpCAM-low PC-3 cells exhibited tumorigenic potential, which depended on mTOR and canonical Wnt signaling, respectively. Finally, serum starvation promoted cell cycle arrest and the acquisition of a quiescent phenotype. It has been well established that there are two major mechanisms that promote G0 entry; the SCF (Fbw7)-c-Myc axis and the Skp2-p27 axis. EpCAM-high PC-3 cancer cells entered the G0 phase via the SCF (Fbw7)-c-Myc axis, while EpCAM-low cells did so via the Skp2-p27 axis. EGF-induced plasticity in EpCAM-high PC-3 cells but not in EpCAM-low PC-3 cells implies that EGFR signaling is likely to be involved in cell cycle re-entry in EpCAM-high PC-3 cells. Discussion: EpCAM regulates the AMPK signaling pathway, which is essential for the response to growth factors, characterized by EGF, in the tumor microenvironment. Furthermore, EpCAM enhances the ability of cells to enter the G0 phase under long-term serum starvation and promotes cell cycle re-entry from this dormancy upon exposure to growth factors. Taken together, these data suggest that “stemness,” including sensitivity to growth factors and plasticity between dormancy and proliferation, is maintained and regulated by EpCAM. Significance: The phenotypes induced by EpCAM expression are mainly responsible for the persistence of minimal residual disease (MRD) and the latent relapse of prostate cancers. Therefore, EpCAM may be a promising therapeutic target to block the ability of prostate cancer CSCs to adapt to the lack of growth factors in the tumor microenvironment.

Microtubule associated tumor suppressor 1 deficient mice develop spontaneous heart hypertrophy and SLE-like lymphoproliferative disease

The microtubule associated tumor suppressor gene 1 (MTUS1) is a recently published tumor suppressor gene, which has also been shown to act as an early component in the growth inhibitory signaling cascade of the angiotensin II type 2 receptor (AT2R). In this study we report the generation of MTUS1 knock-out (KO) mice, which develop normally but reveal higher body weights and slightly decreased blood pressure levels. Twenty-eight percent of the studied MTUS1 KO mice also developed heart hypertrophy and 12% developed nephritis, independent of blood pressure levels. Forty-three percent of the MTUS1 KO mice revealed lymphoid hyperplasia affecting spleen (20%), kidney (37%), lung (23%), lymph nodes (17%), and liver (17%) accompanied with leukocytosis, lymphocytosis, and mild anemia. One animal (3%) developed a marginal zone B-cell lymphoma affecting submandibular salivary gland and regional lymph nodes. The symptoms of all mentioned animals are consistent with a B-cell lymphoproliferative disease with features of systemic lupus erythematosus. In addition, body weight of the MTUS1 KO mice was significantly increased and isolated skin fibroblasts showed increased cell proliferation and decreased cell size, compared to wild-type (WT) fibroblasts in response to depleted FCS concentration and lack of growth factors. In conclusion we herein report the first generation of a MTUS1 KO mouse, developing spontaneous heart hypertrophy and increased cell proliferation, confirming once more the anti-proliferative effect of MTUS1, and a SLE-like lymphoproliferative disease suggesting crucial role in regulation of inflammation. These MTUS1 KO mice can therefore serve as a model for further investigations in cardiovascular disease, autoimmune disease and carcinogenesis.

Coexpression of Bmi-1 and Interleukin-3 Receptor Alpha Chain (CD123) Correlate with Poor Prognosis In Acute Myeloid Leukemia

AbstractAbstract 4324 IntroductionAcute myeloid leukemia (AML) is characterized by the accumulation of immature cells due to disturbed differentiation and proliferation of the myeloid lineage. The traditional AML classification based on morphology, immunophenotyping, and cytogenetic abnormalities is not perfect, in part, because the leukemic population is functionally heterogeneous. AML cells comprise leukemic stem cells (LSCs) and mature leukemia cells that have differentiated abnormally. There has been a recent effort to identify new markers underlying this functional heterogeneity. Bmi-1 is a member of the Polycomb-group (PcG) proteins and is thought to inhibit inhibits cellular senescence and apoptosis. Bmi-1 was also recognized as an essential regulator of the self-renewal capabilities of both hematopoietic stem cells (HSCs) and leukemic stem cells (LSCs). Additional markers of LSCs have been described recently. One of these, interleukin-3 receptor alpha chain (CD123) expressed on AML cells caused higher cycling activity and resistance to apoptosis induced by the lack of growth factor. Coexpression of Bmi-1 and CD123 might be indicative of poor prognosis and might identify patients requiring aggressive therapeutic schedules. Patients and methodsCells lines used included two AML lines (HL-60 and KG-1a), one chronic myeloid leukemia in blast crisis (K562), and one pre-B acute lymphoblastic leukemia (SD-1). A cohort of 58 patients newly diagnosed with AML during the previous five years at our center. Patient BM samples were obtained during routine diagnostic procedures before antineoplastic chemotherapy was started. Diagnosis was based on morphology, cytochemistry, and expression of leukocyte differentiation antigens. All patients were characterized by cytogenetics. Flow-cytometry was used to analyze bone marrow samples to identify Bmi-1+CD123+ population. ResultsPatient samples were divided into 2 groups. Patients in FAB subtypes M0 and M1 comprised group A (N = 20), and patients in all other subtypes comprised group B (N = 38). The median percentages of Bmi-1 positive cells and CD123 positive cells were higher in group A than in group B and healthy controls. There were significant differences in Bmi-1 expression between groups A and B (p = 0.002) and between healthy controls and all AML patients (p = 0.0007). There were no significance differences in CD123 expression between groups A and B but the percentage of CD123 positive cells in healthy controls was significantly lower than in all AML patients (p = 0.0001). Among all AML patients Bmi-1 expression and CD123 expression in CD34+ cells were highly correlated (R = 0.76, p = 0.001). ConclusionsWe thought it important to test coexpression of Bmi-1 and CD123 in the CD34 BM population of AML patients as these markers were both prognostic factors in AML. Our results showed that expression of these markers correlated and together provided an important predictor of prognosis in AML. The criteria of AML stratification are commonly known. However, CD123 and Bmi-1 could become “new” prognostic factors in AML as well as targets for therapeutic approaches. The facts that Bmi-1 is localized in the nucleus (Gil, et al 2005) and is expressed in both hematopoietic and leukemic stem cells (Lessard, et al 2003) makes the hypothetical use of Bmi-1-targeted inhibitors more complex. Thus, further investigation to refine prognosis and to optimize therapy of AML based on Bmi-1 expression in combination with other markers is needed. Disclosures:No relevant conflicts of interest to declare.

Thymic Hypoplasia in Japanese Black Calves with Stillbirth/Perinatal Weak Calf Syndrome

To investigate the relationship between the decreased immunity associated with infirmity and low body weight at birth as a consequence of intrauterine growth retardation in Japanese Black calves with stillbirth/perinatal weak calf syndrome, the thymuses and spleens of 13 calves with this syndrome, weighing less than 20 kg at birth, were examined histopathologically. Cytokeratin staining of the thymus was also carried out to examine its composition. The thymus and spleen were classified as grades 0-4 and I-III according to their hypoplasia, respectively. All calves showed a decreased number of thymocytes. One calf was classified as grade 1, which was characterized by a starry sky appearance. Five calves were classified as grade 2, demonstrating a reversion of the cortex-to-medulla ratio, and the rest were classified as grades 3 and 4 showing an indistinguishable boundary between the cortex and medulla. The thymuses of grade 3 and 4 were occupied by stroma cells, and their Hassall bodies and other structures were rarely observed. Six of 13 calves showed a decreased number of splenocytes, grade II or III, and their red and white pulp regions were unclear. The intrauterine growth retardation caused by lack of growth factors during the fetal period might have induced thymic hypoplasia associated with decreased immunity in the calves with stillbirth/perinatal weak calf syndrome. Therefore, intrauterine growth retardation might be associated with one of the causes of decreased immunity involved in infirmity in this syndrome.

Angiogenesis and Endothelial Cell Repair in Renal Disease and Allograft Rejection

This review discusses the concept that the turnover and replacement of endothelial cells is a major mechanism in the maintenance of vascular integrity within the kidney. CD133+CD34+KDR+ endothelial cell progenitor cells emigrate from the bone marrow and differentiate into CD34+KDR+ expressing cells, which are present in high numbers within the circulation. These progenitor cells are available for recruitment into normal or inflamed tissues to facilitate endothelial cell repair. In several forms of renal disease, proinflammatory insults mediate oxidative stress, senescence, and sloughing of endothelial cells. A lack of growth factors or an inefficient recruitment of endothelial cell progenitors results in hypoxic tissue injury and accelerates the process of chronic renal failure. Augmentation of vascular repair by the provision of growth factors such as vascular endothelial growth factor or by the transfer of progenitor cells directly into the kidney can be protective and prevent ongoing interstitial damage. In allografts, persistent injury results in excessive turnover of graft vascular endothelial cells. Moreover, chronic damage elicits a response that is associated with the recruitment of both leukocytes and endothelial cell progenitors, facilitating an overlapping process of inflammation and angiogenesis. Because the angiogenesis reaction itself is proinflammatory, this process becomes self-sustaining. Collectively, these data indicate that angiogenesis and endothelial cell turnover are important in renal inflammatory processes and allograft rejection. Manipulation of the response may have therapeutic implications to protect against injury and chronic disease processes.

Adhesion to fibronectin via alpha4 integrin (CD49d) protects B cells from apoptosis induced by serum deprivation but not via IgM or Fas/Apo-1 receptors.

Apoptosis is a regulated event crucial to the development and proliferation of normal and malignant B cells. We have studied the role of signals delivered via alpha4 integrin on apoptosis triggered by three different pathways on these cells. For apoptosis induced by serum deprivation, culturing B cells on the recombinant fibronectin fragment H89, a known ligand for alpha4beta1 integrin, resulted in statistically significant (P < 0.005) higher viability values (68%, 65% and 67%) for Ramos, Nalm-6 and EHEB cells, respectively, than culturing cells on poly lysine (42%, 42% and 48%). An antialpha4 MoAb reverted the protecting effect, thus confirming that it was due specifically to alpha4 engagement. Similarly, cells cultured on FN-III4-5, a recently identified fibronectin region which binds activated alpha4 integrin, also showed statistically significant higher viability than poly lysine cultures. Alpha4 engagement however, did not prevent apoptosis induced on Ramos cells via surface IgM. Adhesion of IM-9 cells, a myeloma cell line carrying functional Fas receptors, to the H89 fragment neither increased cell viability upon triggering apoptosis via Fas when compared to poly lysine. These results indicate that alpha4 signalling may overcome B cell apoptosis induced by the lack of growth factors but does not seem to affect the IgM or Fas apoptotic pathways, thus suggesting different intracellular mechanisms for these processes.

Sodium butyrate suppresses apoptosis in human Burkitt lymphomas and murine plasmacytomas bearing c- myc translocations

We report that sodium butyrate, a natural product of fiber degradation by colonic bacteria, markedly suppresses c-Myc-mediated apoptosis induced in murine plasmacytomas and human Burkitt lymphomas by growth factor deprivation, but not in cell lines devoid of c- myc translocations. Attenuation of cell death is associated with downregulation of the rearranged c- myc and activation of pRb via its dephosphorylation. We suggest that in vivo sodium butyrate may play an important role in plasmacytomagenesis by supporting the survival of cells with c- myc translocations, which otherwise would be eliminated by the lack of growth factors.

Administration of hepatic stimulatory substance alone or with other liver growth factors does not ameliorate acetaminophen-induced liver failure

Sixty-two beagle dogs were given three doses of acetaminophen over a period of 24 hr in a fulminant liver failure model that is 70% lethal in 72 hr. Treatment of the animals with hepatic stimulatory substance alone or in a mixture with insulin, transforming growth factor-α and insulin-like growth factor II had no effect on mortality. Evidence of maximum regeneration with a mitotic index 20 to 25 times resting was the same in treated and untreated animals. Similarly, the biochemical and hematological indexes of liver injury were unaffected by therapy. These studies illustrate the futility of treating fulminant liver failure with exogenous growth factors that apparently are already present in large amounts in the natural response to liver injury. The results suggest that on-going liver injury by mechanisms other than lack of growth factors is the central problem of fulminant liver failure. If so, provision of regeneration-stimulating substance is an inappropriate therapeutic strategy. (HEPATOLOGY 1993;17:429–433.)

Administration of hepatic stimulatory substance alone or with other liver growth factors does not ameliorate acetaminophen-induced liver failure

Sixty-two beagle dogs were given three doses of acetaminophen over a period of 24 hr in a fulminant liver failure model that is 70% lethal in 72 hr. Treatment of the animals with hepatic stimulatory substance alone or in a mixture with insulin, transforming growth factor-alpha and insulin-like growth factor II had no effect on mortality. Evidence of maximum regeneration with a mitotic index 20 to 25 times resting was the same in treated and untreated animals. Similarly, the biochemical and hematological indexes of liver injury were unaffected by therapy. These studies illustrate the futility of treating fulminant liver failure with exogenous growth factors that apparently are already present in large amounts in the natural response to liver injury. The results suggest that on-going liver injury by mechanisms other than lack of growth factors is the central problem of fulminant liver failure. If so, provision of regeneration-stimulating substance is an inappropriate therapeutic strategy.

Reversible G2 block in the cell cycle of Ehrlich ascites carcinoma cells

Using flow cytometry we found that proliferation of Ehrlich ascites carcinoma (EAC) cells has been reversibly arrested in the second half of the G2 period at the plateau phase of tumor growth in vivo. The ratio of G2/ Gl cells increased from 0.3 at 6 days post tumor inoculation to 2.5 at 16 days when up to 25–35% of EAC cells are in G2. It was shown that when ascites fluid removal was followed by transferral in culture, G2-blocked cells synchronously entered the G1 phase via mitosis. In the presence of ascites fluid in the culture medium, EAC cells progressed through G1 and S phases but accumulated in G2. Fetal bovine serum, β-mercaptoethanol, and caffeine failed to release cells from the G2 block when added to ascites fluid in culture. It is concluded that neither nutrient depletion nor a lack of growth factors is responsible for the G2 arrest of EAC cells. We suggest that ascites fluid contains a factor(s) which potently interrupts the G2 phase of the cell cycle.

Interspecific Incompatibility in Pinus

McWilliam, J. R. (C. S. I. R. O., Canberra, Australia). Interspecific incompatability in Pinus. Amer. Jour. Bot. 46(6): 425–433. Illus. 1959.—The problem of interspecific incompatibility in several intra- and intersectional crosses in the genus Pinus was investigated using both an anatomical and biochemical approach. To provide a background for this work, the development of ovules after intraspecific pollination and of unpollinated ovules was studied. The development of the gametophytes and fertilization after intraspecific pollination in Austrian pine was regular and showed no major deviation from previous descriptions. Unpollinated ovules of Austrian pine broke down approximately 1 mo. after the strobilus became receptive. The break-down appears to result from the lack of some growth factor in the ovule, which in pollinated ovules is probably initiated by the growth of the pollen tube in the nucellus. Parthenocarpy was not observed, nor could it be induced in unpollinated ovules, and it is considered to be a rare phenomenon in the species. The causes of incompatibility in the crosses studied (slash pine × Austrian pine; red pine × pitch pine; Austrian pine × pitch pine; red pine × Austrian pine; Austrian pine × red pine) appear to be related to the inability of the pollen tubes to function normally in the nucellar tissue of a foreign species. Factors that interfere with this normal development indirectly cause the breakdown of the developing gametophyte, and bring about the ultimate collapse of the ovule. In many respects this pattern of development resembles the situation in unpollinated ovules, and again the lack of a specific growth factor appears to be involved. The initial cause of incompatibility following the cross Austrian pine X red pine may be related to a chemical difference between the ovules of these species. Differences found in the concentration of amino acids, particularly arginine, result in a different chemical environment within the ovule. This may interfere with the normal metabolism of the pollen, affecting either its capacity to germinate or its ability to supply the necessary continued stimulus for the development of the gametophyte. Differences in the pattern and timing of the incompatibility reaction following interspecific pollination may reflect the extent of the genetic diversity between the species. In many crosses between species, the incompatibility reaction does not seem to be complete, as evidenced by the vigorous initial pollen tube growth in occasional ovules.