Application Of The Enzymatic Debridement Of Burn Wounds In Patients During The Covid-19 Epidemic

The unfolding pandemic necessitated optimalization of treatment methods and assurance of the highest precautionary standards to prevent transmission of COVID-19 to burn patients. One of them included an expanded access treatment with the minimally invasive method - enzymatic burn wound debridement using Nexobrid concentrate. The study assessed the effectiveness and usefulness of the expanded treatment project using enzymatic burn wound debridement with Nexobrid concentrate in patients (n=11) during the pandemic (2020) when compared with the results of the same method in a corresponding period of 2019. The concentrate was applied to the wound on the third day following injury at the latest. All patients were treated with the same accepted standards, including initial debridement of the wound, application of Nexobrid concentrate, and removal of devitalized tissue and dressing. Clinical visual assessment of the wound sites confirmed successful debridement of dead tissue following the application of the concentrate. No allergic or adverse reaction, nor significant deterioration of CBC parameters were observed in any patient. Although surgical excision of necrosis is recognized as the method of choice, enzymatic wound debridement using Nexobrid concentrate may contribute to a reduction in epidemiological risk when treating burn patients for several reasons; the procedure can be performed at the patient's bedside, it limits the number of required surgeries, helps to improve medical equipment and supplies management, and saves human resources.

Latin American Association for the study of the liver (ALEH) practice guidance for the diagnosis and treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) currently represents an epidemic worldwide. NAFLD is the most frequently diagnosed chronic liver disease, affecting 20-30% of the general population. Furthermore, its prevalence is predicted to increase exponentially in the next decades, concomitantly with the global epidemic of obesity, type 2 diabetes mellitus (T2DM), and sedentary lifestyle. NAFLD is a clinical syndrome that encompasses a wide spectrum of associated diseases and hepatic complications such as hepatocellular carcinoma (HCC). Moreover, this disease is believed to become the main indication for liver transplantation in the near future. Since NAFLD management represents a growing challenge for primary care physicians, the Asociación Latinoamericana para el Estudio del Hígado (ALEH) has decided to organize this Practice Guidance for the Diagnosis and Treatment of Non-Alcoholic Fatty Liver Disease, written by Latin-American specialists in different clinical areas, and destined to general practitioners, internal medicine specialists, endocrinologists, diabetologists, gastroenterologists, and hepatologists. The main purpose of this document is to improve patient care and awareness of NAFLD. The information provided in this guidance may also be useful in assisting stakeholders in the decision-making process related to NAFLD. Since new evidence is constantly emerging on different aspects of the disease, updates to this guideline will be required in future.

Evaluating the Efficacy of a Cognitive Skills Training Program for Spanish-Speaking Adults with Subjective Cognitive Complaints

Objective

The purpose of this pilot study was to examine the efficacy of a five-week Spanish cognitive skills training program on 18 participants with subjective cognitive complaints.

Participants and Method

Eighteen Spanish-speaking participants completed a series of cognitive and emotional measures pre- and post-training, including objective measures of cognitive functioning (Montreal Cognitive Assessment, Spanish-version; MoCA), self-reported mood measures (Beck Depression Inventory, BDI; Beck Anxiety Inventory, BAI-Spanish version), and subjective cognitive complaints questionnaire (Subjective Cognitive Decline Questionnaire, Spanish version). Drawing from existing literature on effective interventions for subjective cognitive impairment (Reijnders et al., 2015), this research focused on delivering a five-week intervention program in Spanish, which included psychoeducation on cognition, cognitive strategy training, and applied practice of mindfulness techniques. Furthermore, this intervention incorporated Personalismo and indirect communication, which was applied by engaging with participants in a warm and culturally appropriate manner (Jiménez et al., 2014).

Results

Participants demonstrated significant improvement in overall MoCA scores. Improvements in subjective cognitive performance, as well as decreases in depression and anxiety (as indicated by the BDI and BAI, respectively) were noted. Results also showed that changes in mood, anxiety, and subjective cognitive performance were not predictive of improvements in MoCA performance, lending support to the hypothesis that skills learned in the program contributed to improved cognitive performance.

Conclusions

Overall, these results demonstrate that linguistically and culturally tailored psychoeducation regarding cognition, cognitive skills training, and mindfulness, can positively impact subjective and objective cognitive performance, as well as psychological wellbeing among Spanish-speaking adults.

References

Jiménez, A.L., Alegría, M., Camino-Gaztambide, R.F., & Zayas I, L.V. (2014) Cultural sensitivity: What should we understand about Latinos? In R. Parekh (ed.) The Massachusetts General Hospital Textbook on Diversity and Cultural Sensitivity in Mental Health (pp.61-70). New York, NY: Springer. Rebok, G. W., Ball, K., Guey, L. T., Jones, R. N., Kim, H. Y., King, J. W., … ACTIVE Study Group (2014). Ten-year effects of the advanced cognitive training for independent and vital elderly cognitive training trial on cognition and everyday functioning in older adults. Journal of the American Geriatrics Society, 62(1), 16–24. doi:10.1111/jgs.12607.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Granulation and microbial community dynamics in the chitosan-supplemented anaerobic treatment of wastewater polluted with organic solvents

The effect of chitosan on the development of granular sludge in upflow anaerobic sludge blanket reactors (UASB) when treating wastewater polluted with the organic solvents ethanol, ethyl acetate, and 1-ethoxy-2-propanol was evaluated. Three UASB reactors were operated for 219 days at ambient temperature with an organic loading rate (OLR) of between 0.3 kg COD m^-3 d^-1 and 20 kg COD m^-3 d^-1. One reactor was operated without the addition of chitosan, while the other two were operated with the addition of chitosan doses of 2.4 mg gVSS^-1 two times. The three reactors were all able to treat the OLR tested with COD removal efficiencies greater than 90%. However, the time required to reach stable operation was considerably reduced in the chitosan-assisted reactors. The development of granules in the reactors with chitosan was accelerated and granules larger than 2000 μm were only observed in these reactors. In addition, these granules exhibited better physicochemical characteristics: the mean particle diameter (540 and 613 μm) was approximately two times greater than in the control reactor (300 μm), and the settling velocities exceeded 35 m h^-1. The extracellular polymeric substances (EPS) in the reactors with the chitosan was found to be higher than in the control reactor. The protein-EPS content has been correlated with the granule size. The analyses of the microbial communities, performed through denaturing gradient gel electrophoresis and high-throughput sequencing, revealed that the syntrophic microorganisms belonging to genus Geobacter and the hydrogenotrophic methanogen Methanocorpusculum labreanum were predominant in the granules. Other methanogens like Methanosaeta species were found earlier in the chitosan-assisted reactors than in the control reactor.

Supernumerary renal vessels: analysis of frequency and configuration in 996 computed tomography studies

BACKGROUND

Number, course and division pattern of renal vessels is highly variable. Variant renal vasculature is of high interest in nephrectomy for the renal transplantations, both in deceased and living donors. The purpose of the study was to analyse the frequency of supernumerary renal vessels in a large cohort of patients undergoing the multiphase abdominopelvic computed tomography (CT), as well as analyse the possible patterns of coexisting supernumerary arteries in veins.

MATERIALS AND METHODS

A retrospective analysis of abdominopelvic CT studies within 1 year period was performed. In each study, number of renal arteries and veins was recorded. Course of left renal vein was classified into normal, retro- or periaortic. For statistical analysis of normal distribution data, t-Student test was used. Chi-square test was used for frequency of variant vessel distribution. Pearson correlation coefficient was used for the analysis of coexistence of supernumerary vessels.

RESULTS

996 patients were included in the analysis, male to female ratio: 481:515 (48%:52%). Mean age was 57.9 ± 14.7 years. Single renal arteries were observed in 73% of cases, while single renal veins in 95%. Circumaortic or retroaortic courses of left renal veins were observed in 10% of cases. Number of renal vessels has been compared in patients with and without supernumerary vessels. In patients with supernumerary left renal artery, significantly more right renal vessels were observed. In patients with supernumerary right renal vein, mean number of all remaining vessels was significantly higher.

CONCLUSIONS

Supernumerary renal vessels are a frequent finding in abdominal CT studies. Finding a supernumerary vessel should increase awareness of possible other supernumerary renal vessels.

Anatomical variations of the coeliac trunk in the homogeneous Polish population

BACKGROUND

The abdominal vessels show a number of abnormalities and pathologies knowledge of which is important during open as well as laparoscopic surgeries. One of the most common vessels which pattern has many variations is the coeliac trunk. The present study was undertaken on homogeneous population to assess morphology of the coeliac trunk and to evaluate the possible variability of its branches.

MATERIALS AND METHODS

Standard abdominal multidetector computed tomography examinations were performed on a total of 1569 patients diagnosed by 2 radiologists independently; in case of doubts common assessment was performed.

RESULTS

The coeliac trunk followed the classic pattern in 92.7% of the cases (1455/1569 of patients). The gastrosplenic trunk was detected in 4.1% of cases (64/1569); the hepatosplenic trunk in 2.2% of cases (34/1569); the coeliac-mesenteric trunk was observed in 0.5% of cases (8/1569); the hepatogastric trunk in 0.2% of cases (4/1569); the splenomesenteric trunk was detected in 0.1% of cases (2/1569). In the next 0.1% the coeliac trunk was absent. The hepatosplenomesenteric and the coeliac-colic trunk were not observed in the study population.

CONCLUSIONS

Vascular anatomical abnormality is usually asymptomatic hovewer, its preoperative knowledge is helpful to reduce complications like vascular bleeding when dissecting the hapato-pancreatic region. The coeliac trunk and its branches can be fast and easy evaluated in computed tomography exams performed due to various symptoms from abdominal cavity.

CHACO outreach project: the development of a primary health care-based medical genetic service in an Argentinean province

Dissemination of knowledge in genetics to be applied in medicine has created a growing need for capacity building in health care workers. The CAPABILITY ARGENTINA outreach project protocol was designed as a model to introduce genetics in areas without genetic services. Our aim was for genetic health care to become part of primary care in an Argentine province lacking genetic services. The program was innovative as professionals from the referral center (Garrahan Hospital S.A.M.I.C.) traveled to remote areas to train professionals through problem-based education. A logical framework was designed for a local needs assessment. Teaching materials (Powerpoint presentations, printed syllabus, and CD) and a web page were developed. A demonstration project was carried out in the Province of Chaco, Argentina. A total of 485 health workers were trained. The number of consultations increased significantly in participating areas comparing before and after the training period. To support this increase, a complementary project was set up from a public hospital sponsored from within Argentina to build a cytogenetic laboratory in the capital of the Province of Chaco. The model was improved for reproduction in other areas in Argentina. CAPABILITY ARGENTINA is a capacity building model for training of primary care professionals in genetics that may be applied to other medical specialties. The outcomes of the programme have a direct impact on clinical practice.

Volumetric reconstruction of the right ventricle improves reproducibility of interventricular septum bowing in patients with pulmonary embolism

Bowing of the interventricular septum (IVS) is a sign of severe pulmonary embolism(PE); however, it is affected by high interobserver variability. The aim of the study was to evaluate the application of volumetric reconstructions of the right ventricle for assessment of IVS position regarding its accuracy in identifying right ventricular dysfunction, as well as interobserver agreement in evaluating this sign.IVS bowing was evaluated with multiplanar reformations (MPR) and volumetric reconstruction (VR, volume rendering) by 2 observers. The accuracy of IVS bowing sign was better for VR-based assessment; however, it was not significantly better than the MPR-based evaluation. Interobserver agreement was found to be fair (kappa = 0.381) for the MPR-based grading of IVS position as normal orabnormal, while it was significantly better for the VR method (kappa = 0.629,p < 0.001). The VR-based method may improve utilisation of IVS bowing sign inpatients with PE.

Application of rapid prototyping techniques for modelling of anatomical structures in medical training and education

Rapid prototyping has become an innovative method of fast and cost-effective production of three-dimensional models for manufacturing. Wide access to advanced medical imaging methods allows application of this technique for medical training purposes. This paper presents the feasibility of rapid prototyping technologies: stereolithography, selective laser sintering, fused deposition modelling, and three-dimensional printing for medical education. Rapid prototyping techniques are a promising method for improvement of anatomical education in medical students but also a valuable source of training tools for medical specialists.

The course of the cystic artery during laparoscopic cholecystectomy

Proper recognition of the particular structures that form the triangle of Calot is essential for the proper and safe performance of laparoscopic cholecystectomy. Proper recognition, ligation, and cut of the cystic duct and cystic artery with branches (dorsal and ventral) remain an integral condition for the removal of the gallbladder. Calot's triangle, as an orientation structure, determines the most common location of the cystic artery. The triangle of Calot is one of the most variable regions of the abdomen in terms of anatomy. The aim of this study was to evaluate how important for surgery is the detailed anatomical recognition of the main branches of the cystic artery in Calot's triangle during laparoscopic cholecystectomy. Relations of the main branches of the cystic artery were evaluated in 88 patients that underwent laparoscopic cholecystectomy at the Department of General Surgery of the District Specialistic Hospital of Lublin. The anatomical relations of cystic duct and artery were classified into typical and variant types. Significantly more frequently variants of cystic artery were observed in women. However, the time of the procedure was not significantly related with the type of cystic artery.

Spiegelian hernia - - anatomy, diagnosing and imaging difficulties-report of 2 cases

Spiegelian hernias account for less than 1% of all hernias diagnosed in the adult population. The most important factors in the proper diagnostic process are detailed physical examination combined with imaging procedures. Two cases of Spiegelian hernias are presented. The anatomical background of the pathology, as well as diagnostic procedures and surgical treatment, is discussed.

The body constitution of patients and intubation scales as predictors of difficult intubation considered in relation to the experience of the intubator

The aims of the study were to identify factors that may result in difficulties in intubation, and to compare the results obtained when an experienced and when a less experienced anaesthesiologist was involved. The 96 patients included in the study were evaluated for difficult intubation according to the following scales: Mallampati, upper lip bite test (ULBT) and Patil. The mobility of the cervical segments of the vertebral column, the distance between the jugular notch of the sternum and the chin and the anatomical constitution of the body were other factors that were taken into consideration. Statistical analysis was performed in order to identify factors that may result in difficulties in intubation for an experienced and for a less experienced anaesthesiologist.

Putative markers of infective life stages in Leishmania (Viannia) braziliensis

Gene expression is known to vary significantly during the Leishmania life-cycle. Its monitoring might allow identification of molecular changes associated with the infective stages (metacyclics and amastigotes) and contribute to the understanding of the complex host-parasite relationships. So far, very few studies have been done on Leishmania (Viannia) braziliensis, one of the most pathogenic species. Such studies require, first of all, reference molecular markers. In the present work, we applied differential display analysis (DD analysis) in order to identify transcripts that might be (i) candidate markers of metacyclics and intracellular amastigotes of L. (V.) braziliensis or (ii) potential controls, i.e. constitutively expressed. In total, 48 DNA fragments gave reliable sequencing data, 29 of them being potential markers of infective stages and 12 potential controls. Eight sequences could be identified with reported genes. Validation of the results of DD analysis was done for 4 genes (2 differentially expressed and 2 controls) by quantitative real-time PCR. The infective insect stage-specific protein (meta 1) was more expressed in metacyclic-enriched preparations. The oligopeptidase b showed a higher expression in amastigotes. Two genes, glucose-6-phosphate dehydrogenase and a serine/threonine protein kinase, were found to be similarly expressed in the different biological samples.

What do clinicians think of the anatomical knowledge of medical students? Results of a survey

Human anatomy is one of basic courses in medical education. It usually takes place during the first year of the medical school syllabus. However, the results of the course, if defined as profound anatomical knowledge, are not applied by the students until several years after the final anatomy examination. The aim of the study was to evaluate the anatomical knowledge of senior medical students. For this reason a survey was distributed among teachers responsible for clinical rotas. The results of the study were intended to give the answer to the question, "What do students remember several years after the anatomy examination?" as expressed by their clinical teachers. The questionnaire included four closed questions and one open question. The closed questions concerned general anatomical knowledge, whether the anatomy course should be extended and whether additional courses should be introduced and included a question about student knowledge of particular systems. The open question concerned ways of improving anatomical education. As a result of the survey it was observed that surgical specialists had a significantly lower opinion of the medical knowledge of their students than had medical specialists. Most of the suggestions for improving anatomical education were related to introducing clinical applications of anatomical knowledge.

Cytokine response in the postoperative period after surgical treatment of benign adnexal masses: comparison between laparoscopy and laparotomy

BACKGROUND

Cytokines are the main mediators of the inflammation and the response to trauma. The purpose of the present study was the comparative assessment in sera of patients with benign adnexal masses treated by laparoscopy or laparotomy of the following proinflammatory and anti-inflammatory cytokines: interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha), and IL-10 in the early postoperative period.

METHODS

A total of 40 patients with benign adnexal masses were studied; 25 of whom underwent laparoscopy and 15, laparotomy. Blood serum concentration of IL-1beta, IL-6, IL-8, TNF-alpha, and IL-10 were measured by commercially available ELISA assays before and 4 h, 24 h, and 48 h after the operation.

RESULTS

Concentrations of IL-6 were significantly increased in both groups at 4 h, 24 h, and 48 h after the surgery; levels of IL-10 showed a significant increase 4 h and 24 h after the operation; an increase in IL-1beta levels was observed only after laparotomy; no significant variations were observed in serum levels of IL-8; the postoperative increase of IL-1beta, IL-6, and IL-10 levels was more pronounced in patients undergoing laparotomy than in those treated laparoscopically; length of the surgical procedure, amount of CO2 used, tumor diameter, age, and body mass index (BMI) of the patients did not influence the postoperative patterns of the studied cytokines.

CONCLUSIONS

Systemic cytokine response after operations for benign adnexal masses depends on the degree of the surgical trauma, and is less pronounced in patients undergoing laparoscopy.

Microcyntm: a novel super-oxidized water with neutral pH and disinfectant activity

A new super-oxidized water (SOW) product, Microcyn, was tested for in vitro antimicrobial and antiviral activities. The effectiveness of this neutral-pH SOW at killing Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Candida albicans in pure culture was evaluated. One millilitre (approximately 10(8)colony-forming units/mL) of each micro-organism was subjected to 9 mL Microcyn or sterile water at room temperature for 30s. Under these conditions, a log(10) reduction factor of 8 in the level of all pathogens occurred in the treatment samples. In addition, results of tests with three batches of Microcyn exposed to Bacillus atrophaeus spores for 5 min demonstrated complete inactivation of the spores within 2-3 min (log(10) reduction factor >4). The effectiveness of Microcyn in reducing human immunodeficiency virus-1 (HIV-1) on hard surfaces (glass) was also evaluated in compliance with Environmental Protection Agency requirements for virucidal claims. After exposure of the tested surfaces to Microcyn for 5 min without agitation, there was a log(10) reduction factor >3 in the viral load as measured by both cytopathic effect and antigen p24 of HIV-1 production in MT-2 cultures. Microcyn activity against adenoviral vector type 5 was also analysed under simulated laboratory in-use conditions with viral suspensions. In order to increase the sensitivity of the test, the fluorescent light emitted by AdGFP-infected cells was measured with the use of a flow cytometer. A log(10) reduction factor >3 in the viral load was achieved after a 5-min exposure to Microcyn under these strict conditions. These results show that Microcyn exerts a wide antimicrobial spectrum with major advantages over acidic SOWs, including neutral pH, lower free active chlorine (51-85 ppm) and long shelf life (1 year).

[Visual extinction: a study by means of potentials evoked with movement]

INTRODUCTION

The term extinction refers to the phenomenon in which a patient with a lesion of the central nervous system ignores one of two stimuli in conditions of simultaneous bilateral stimuli. Various studies observe this phenomenon as the expression of a deficit in the process of selective attention, but there are few studies with potentials related to events (PRE).

OBJECTIVES

To find the possible electrical correlation of the extinction phenomenon and the stage of processing at which this occurs.

PATIENTS AND METHODS

We studied a patient with a right parieto occipital lesion and a control person of the same race, age, sex and educational level. We carried out two experiments. The first of these was to determine the direction of movement of two surfaces with red and green spots situated on both sides of a central fixation point. In the second experiment, the same task was carried out, but the two surfaces were superimposed, in the same place. In both cases the first movement occurred in the surface which was being attended to and the second might be this surface or the other. The proportion of correct answers were recorded for both movements. The PRE showed an attention disorder which affected the spatial distribution of attention with conservation of the attention to objects.

CONCLUSIONS

The suppression of the P1 N1 components are the electrical correlate of the phenomenon of extinction which should occur during early stages of processing. Further investigations are necessary in a larger number of cases.

Attentional shifts between surfaces: effects on detection and early brain potentials

Two consecutive events transforming the same illusory surface in transparent motion (brief changes in direction) can be discriminated with ease, but a prolonged interference ( approximately 500 ms) on the discrimination of the second event arises when different surfaces are concerned [Valdes-Sosa, M., Cobo, A., & Pinilla, T. (2000). Attention to object files defined by transparent motion. Journal of Experimental Psychology: Human Perception and Performance, 26(2), 488-505]. Here we further characterise this phenomenon and compare it to the attentional blink AB [Shapiro, K.L., Raymond, J.E., & Arnell, K.M. (1994). Attention to visual pattern information produces the attentional blink in RSVP. Journal of Experimental Psychology: Human Perception and Performance, 20, 357-371]. Similar to the AB, reduced sensitivity (d') was found in the two-surface condition. However, the two-surface cost was associated with a reduced N1 brain response in contrast to reports for AB [Vogel, E.K., Luck, S.J., & Shapiro, K. (1998). Electrophysiological evidence for a postperceptual locus of suppression during the attentional blink. Journal of Experimental Psychology: Human Perception and Performance, 24(6), 1656-1674]. The results from this study indicate that the two-surface cost corresponds to competitive effects in early vision. Reasons for the discrepancy with the AB study are considered.

Cross-talk between insulin receptor and integrin alpha5 beta1 signaling pathways

The ligation and clustering of cell surface alphabeta heterodimeric integrins enhances cell adhesion and initiates signaling pathways that regulate such processes as cell spreading, migration, differentiation, proliferation and apoptosis. Here we show that insulin treatment of Chinese hamster ovary cells expressing insulin receptors (CHO-T) markedly promotes cell adhesion onto a fibronectin matrix, but not onto bovine serum albumin or poly-lysine. Incubation of cells with a GRGDSP peptide that specifically binds integrins (but not the nonspecific GRADSP peptide) abolishes this insulin effect, as does the potent phosphoinositide 3-kinase (PI 3-kinase) inhibitor wortmannin. Moreover, a specific blocking monoclonal anti-alpha5beta1 integrin antibody, PB-1, blocks insulin-stimulated cell adhesion onto fibronectin. Conversely, activating alpha5beta1 integrins on CHO-T cells by adherence onto fibronectin markedly potentiates the action of insulin to enhance insulin receptor and insulin receptor substrate (IRS)-1 tyrosine phosphorylation. Activation of alpha5beta1 integrin also markedly potentiates the recruitment of p85-associated PI 3-kinase activity to IRS-1 in response to submaximal levels of insulin in CHO-T cells. These data indicate that insulin potently activates integrin alpha5beta1 mediated CHO-T cell adhesion, while integrin alpha5beta1 signaling in turn enhances insulin receptor kinase activity and formation of complexes containing IRS-1 and PI 3-kinase. These findings raise the hypothesis that insulin receptor and alpha5beta1 integrin signaling act synergistically to enhance cell adhesion.

Mechanisms of Taxol-induced cell death are concentration dependent

Although the ability of Taxol to stabilize cellular microtubules is well accepted, the mechanisms by which Taxol induces growth arrest and cell death remain unclear. Recent evidence indicates that Taxol alters specific intracellular signal transduction events, such as the activation of Raf-1 kinase, that may be essential for drug-induced apoptosis. To determine whether Raf-1 kinase activation occurs at different concentrations of Taxol and in response to disruption of the normal microtubule cytoskeleton, A549 cells were treated with different concentrations of Taxol after which Raf-1 activation and the microtubule cytoskeleton were analyzed. Raf-1 activation was observed at Taxol concentrations of 9 nM and greater. However, disruption of the normal microtubule cytoskeleton was seen at lower Taxol concentrations (1-7 nM), indicating that this process begins in the absence of Raf-1 activation. Raf-1 activation correlated with the induction of a G2-M block. Depletion of Raf-1 resulted in the accumulation of cells in the G2-M phase of the cell cycle, suggesting that Raf-1 may play an important role in the passage through mitosis. Supporting this idea, Raf-1 was activated in mitotic cells. Low concentrations of Taxol induced cell death in the absence of Raf-1 activation, indicating that Taxol-induced cell death is not dependent on Raf-1 activation. At concentrations of drug lower than the critical concentration required for Raf-1 activation, p53 and p21(WAF-1) were induced independently of Raf-1. These studies suggest that Taxol-mediated cell death may result from two different mechanisms. At low Taxol concentrations (< 9 nM), cell death may occur after an aberrant mitosis by a Raf-1 independent pathway, whereas at higher Taxol concentrations (> or = 9 nM) cell death may be the result of a terminal mitotic arrest occurring by a Raf-1-dependent pathway.

Expression of proliferation-associated nuclear autoantigens, p330d/CENP-F and PCNA, in differentiation and in drug-induced growth inhibition using two-parameter flow cytometry

p330d/CENP-F is a recently described nuclear autoantigen that was detected in PHA-stimulated but not in resting peripheral lymphocytes. This protein accumulates in the nucleus during S-phase and reaches maximum levels during the G2 and M phases of the cell cycles. We compared the expression of p330d/CENP-F and proliferating cell nuclear antigen (PCNA) during the induction of terminal myeloid differentiation of HL-60 tumour cells. HL-60 cells were induced to differentiate with retinoic acid (RA), dimethyl sulfoxide (DMSO), and 3-nitrobenzothiazolo [3,2-]quinolinium (NBQ), and collected at different intervals. Control and treated cells were analyzed by two-parameter flow cytometry using propidium iodide and antibodies to p330d/CENP-F and PCNA. The percentage of p330d/CENP-F and PCNA positive cells was found to be proportional to the percentage of proliferating cells. After two cell cycles (65 h), the percentage of p330d/CENP-F and PCNA positive cells was reduced proportionately to the number of cells that had differentiated. Reduction in the expression of both antigens was completed after 120 h when 80% to 85% of the cells were arrested in G1 and displayed the mature phenotype. The expression of p330d/CENP-F and PCNA was also assessed in the growth inhibition of HT-29 cells induced by various concentrations of camptothecin (CPT), etoposide (VP-16), and aphidicolin (APH). There was a dose-dependent displacement of cells to late S-phase by CPT while VP-16 induced cells to accumulate in G2+M, and as expected these effects caused a strong increase in the cellular levels of both antigens. The arrest of cells in G1 by APH led to a significant decrease in their expression. The dramatic reduction in p330d/CENP-F levels during differentiation, and the correlation of its expression with the cell cycle effects of the cytotoxic drugs are consistent with the behaviour expected for a proliferation marker.

Topoisomerase I-related parameters and camptothecin activity in the colon carcinoma cell lines from the National Cancer Institute anticancer screen

Camptothecin (CPT) derivatives are a new family of anticancer agents which are selective inhibitors of DNA topoisomerase I (top1) and have entered clinical trials with promising results. The cellular determinants for CPT activity were studied in the seven cell lines of the National Cancer Institute anticancer screen. These cell lines exhibit natural differences in sensitivity to CPT and can be divided into three groups, according to their increasing resistance: colo205, SW620, HCT116 < HT29, HCC2998 < HCT15, and KM12. The differential sensitivity range was approximately 17-fold between KM12 and colo205 cells. CPT uptake varied only by less than a factor of three among the cell lines. Top1 mRNA, measured by Northern blotting analysis, and top1 protein levels, measured by Western blotting, varied by 2-fold or less among the cell lines and were correlated neither with the CPT cytotoxicity nor the levels of cleavable complexes measured by alkaline elution in the various cell lines. An overall log-linear correlation was observed between CPT-induced top1-cleavable complexes and growth inhibition, indicating the importance of cleavable complex formation rather than top1 levels for cell killing in this panel of cell lines. Also, some cell lines displayed marked growth inhibition differences with minimal differences in cleavable complexes and S-phase fraction, suggesting that parameters downstream from the cleavable complexes are also critical for CPT cytotoxicity.