Raman microspectroscopy reveals unsaturation heterogeneity at the lipid droplet level and validates an in vitro model of bone marrow adipocyte subtypes

Bone marrow adipocytes (BMAds) constitute the most abundant stromal component of adult human bone marrow. Two subtypes of BMAds have been described, the more labile regulated adipocytes (rBMAds) and the more stable constitutive adipocytes (cBMAds), which develop earlier in life and are more resilient to environmental and metabolic disruptions. In vivo, rBMAds are enriched in saturated fatty acids, contain smaller lipid droplets (LDs) and more readily provide hematopoietic support than their cBMAd counterparts. Mouse models have been used for BMAds research, but isolation of primary BMAds presents many challenges, and thus in vitro models remain the current standard to study nuances of adipocyte differentiation. No in vitro model has yet been described for the study of rBMAds/cBMAds. Here, we present an in vitro model of BM adipogenesis with differential rBMAd and cBMAd-like characteristics. We used OP9 BM stromal cells derived from a (C57BL/6xC3H)F2-op/op mouse, which have been extensively characterized as feeder layer for hematopoiesis research. We observed similar canonical adipogenesis transcriptional signatures for spontaneously-differentiated (sOP9) and induced (iOP9) cultures, while fatty acid composition and desaturase expression of Scd1 and Fads2 differed at the population level. To resolve differences at the single adipocyte level we tested Raman microspectroscopy and show it constitutes a high-resolution method for studying adipogenesis in vitro in a label-free manner, with resolution to individual LDs. We found sOP9 adipocytes have lower unsaturation ratios, smaller LDs and higher hematopoietic support than iOP9 adipocytes, thus functionally resembling rBMAds, while iOP9 more closely resembled cBMAds. Validation in human primary samples confirmed a higher unsaturation ratio for lipids extracted from stable cBMAd-rich sites (femoral head upon hip-replacement surgery) versus labile rBMAds (iliac crest after chemotherapy). As a result, the 16:1/16:0 fatty acid unsaturation ratio, which was already shown to discriminate BMAd subtypes in rabbit and rat marrow, was validated to discriminate cBMAds from rBMAd in both the OP9 model in vitro system and in human samples. We expect our model will be useful for cBMAd and rBMAd studies, particularly where isolation of primary BMAds is a limiting step.

Traumatic injuries in primary dentition and their immediate and long-term consequences: a 10-year retrospective study from the State University of Rio de Janeiro, Brazil

BACKGROUND/AIM

Dental trauma is a highly prevalent problem worldwide. The aim of this study was to describe characteristics of trauma to anterior primary teeth and its sequelae for primary and successor teeth over a 10-year period of assistance at the paediatric dental traumatology clinic in the State University of Rio de Janeiro, Brazil.

MATERIALS AND METHODS

The data were obtained from the dental records of children assisted from 2006 to 2016. Inclusion criteria were trauma to anterior primary teeth; aged <1 to 9 years at the time of trauma; and at least one follow-up appointment. The data concerning traumatized teeth, child's age, soft tissue injuries, types of traumatic dental injuries and sequelae in both dentitions were collected.

RESULTS

Of the 1230 dental records, 483 (39.3%) were eligible, consisting of 815 teeth. The mean age at the time of trauma was 37.4 months (239 males and 244 females). The most important characteristics were: tooth 51 was most affected; falls, at home, on a ceramic floor, were the main cause; gingival laceration, enamel fracture and intrusive luxation were the most frequent types of trauma; premature tooth loss of primary teeth and enamel discoloration in their successor were the most frequent sequelae; and injuries in the periodontal tissue were demonstrated as the highest risk for sequelae in successors (OR, 3.798; p< 0.001).

CONCLUSIONS

Most traumatic injuries occur in young children, in their home environment. Consequences for the primary teeth were more frequent compared to the permanent successor tooth. Traumatized primary teeth involving periodontal tissue have more chances to result in sequelae to their successor teeth.

The NAD-Booster Nicotinamide Riboside Potently Stimulates Hematopoiesis through Increased Mitochondrial Clearance

It has been recently shown that increased oxidative phosphorylation, as reflected by increased mitochondrial activity, together with impairment of the mitochondrial stress response, can severely compromise hematopoietic stem cell (HSC) regeneration. Here we show that the NAD⁺-boosting agent nicotinamide riboside (NR) reduces mitochondrial activity within HSCs through increased mitochondrial clearance, leading to increased asymmetric HSC divisions. NR dietary supplementation results in a significantly enlarged pool of progenitors, without concurrent HSC exhaustion, improves survival by 80%, and accelerates blood recovery after murine lethal irradiation and limiting-HSC transplantation. In immune-deficient mice, NR increased the production of human leucocytes from hCD34+ progenitors. Our work demonstrates for the first time a positive effect of NAD⁺-boosting strategies on the most primitive blood stem cells, establishing a link between HSC mitochondrial stress, mitophagy, and stem-cell fate decision, and unveiling the potential of NR to improve recovery of patients suffering from hematological failure including post chemo- and radiotherapy.

MarrowQuant Across Aging and Aplasia: A Digital Pathology Workflow for Quantification of Bone Marrow Compartments in Histological Sections

The bone marrow (BM) exists heterogeneously as hematopoietic/red or adipocytic/yellow marrow depending on skeletal location, age, and physiological condition. Mouse models and patients undergoing radio/chemotherapy or suffering acute BM failure endure rapid adipocytic conversion of the marrow microenvironment, the so-called "red-to-yellow" transition. Following hematopoietic recovery, such as upon BM transplantation, a "yellow-to-red" transition occurs and functional hematopoiesis is restored. Gold Standards to estimate BM cellular composition are pathologists' assessment of hematopoietic cellularity in hematoxylin and eosin (H&E) stained histological sections as well as volumetric measurements of marrow adiposity with contrast-enhanced micro-computerized tomography (CE-μCT) upon osmium-tetroxide lipid staining. Due to user-dependent variables, reproducibility in longitudinal studies is a challenge for both methods. Here we report the development of a semi-automated image analysis plug-in, MarrowQuant, which employs the open-source software QuPath, to systematically quantify multiple bone components in H&E sections in an unbiased manner. MarrowQuant discerns and quantifies the areas occupied by bone, adipocyte ghosts, hematopoietic cells, and the interstitial/microvascular compartment. A separate feature, AdipoQuant, fragments adipocyte ghosts in H&E-stained sections of extramedullary adipose tissue to render adipocyte area and size distribution. Quantification of BM hematopoietic cellularity with MarrowQuant lies within the range of scoring by four independent pathologists, while quantification of the total adipocyte area in whole bone sections compares with volumetric measurements. Employing our tool, we were able to develop a standardized map of BM hematopoietic cellularity and adiposity in mid-sections of murine C57BL/6 bones in homeostatic conditions, including quantification of the highly predictable red-to-yellow transitions in the proximal section of the caudal tail and in the proximal-to-distal tibia. Additionally, we present a comparative skeletal map induced by lethal irradiation, with longitudinal quantification of the "red-to-yellow-to-red" transition over 2 months in C57BL/6 femurs and tibiae. We find that, following BM transplantation, BM adiposity inversely correlates with kinetics of hematopoietic recovery and that a proximal to distal gradient is conserved. Analysis of in vivo recovery through magnetic resonance imaging (MRI) reveals comparable kinetics. On human trephine biopsies MarrowQuant successfully recognizes the BM compartments, opening avenues for its application in experimental, or clinical contexts that require standardized human BM evaluation.

Injectable, scalable 3D tissue-engineered model of marrow hematopoiesis

Modeling the interaction between the supportive stroma and the hematopoietic stem and progenitor cells (HSPC) is of high interest in the regeneration of the bone marrow niche in blood disorders. In this work, we present an injectable co-culture system to study this interaction in a coherent in vitro culture and in vivo transplantation model. We assemble a 3D hematopoietic niche in vitro by co-culture of supportive OP9 mesenchymal cells and HSPCs in porous, chemically defined collagen-coated carboxymethylcellulose microscaffolds (CCMs). Flow cytometry and hematopoietic colony forming assays demonstrate the stromal supportive capacity for in vitro hematopoiesis in the absence of exogenous cytokines. After in vitro culture, we recover a paste-like living injectable niche biomaterial from CCM co-cultures by controlled, partial dehydration. Cell viability and the association between stroma and HSPCs are maintained in this process. After subcutaneous injection of this living artificial niche in vivo, we find maintenance of stromal and hematopoietic populations over 12 weeks in immunodeficient mice. Indeed, vascularization is enhanced in the presence of HSPCs. Our approach provides a minimalistic, scalable, biomimetic in vitro model of hematopoiesis in a microcarrier format that preserves the HSPC progenitor function, while being injectable in vivo without disrupting the cell-cell interactions established in vitro.

High-throughput, nonperturbing quantification of lipid droplets with digital holographic microscopy

In vitro differentiating adipocytes are sensitive to liquid manipulations and have the tendency to float. Assessing adipocyte differentiation using current microscopy techniques involves cell staining and washing, while using flow cytometry involves cell retrieval in suspension. These methods induce biases, are difficult to reproduce, and involve tedious optimizations. In this study, we present digital holographic microscopy (DHM) as a label-free, nonperturbing means to quantify lipid droplets in differentiating adipocytes in a robust medium- to high-throughput manner. Taking advantage of the high refractive index of lipid droplets, DHM can assess the production of intracellular lipid droplets by differences in phase shift in a quantitative manner. Adipocytic differentiation, combined with other morphological features including cell confluence and cell death, was tracked over 6 days in live OP9 mesenchymal stromal cells. We compared DHM with other currently available methods of lipid droplet quantification and demonstrated its robustness with modulators of adipocytic differentiation in a dose-responsive manner. This study suggests DHM as a novel marker-free nonperturbing method to study lipid droplet accumulation and may be envisioned for drug screens and mechanistic studies on adipocytic differentiation.

Cellular endogenous NAD(P)H fluorescence as a label-free method for the identification of erythrocytes and reticulocytes

Reticulocytes and erythrocytes are the ultimate differentiated stages of erythropoiesis. In addition to being anucleate cells, they are characterized by the clearance of their mitochondrial pool or lack thereof. Given that for most research-oriented flow cytometry experiments erythrocytes and reticulocytes are often undesirable cell types, their identification and exclusion from analyses can be essential. Here, we describe a flow cytometric method based on cellular NAD(P)H-related autofluorescence, whose localization is mainly associated with mitochondria. By increasing the sensitivity of the specific NAD(P)H-fluorescence detector, we discovered a population with weak levels of NAD(P)H fluorescence signals whose immunophenotypical and physiological characterization in mouse bone marrow led to its identification as both erythrocytes and reticulocytes. Our method showed comparable sensitivity and specificity to the detection of red blood cells based on the absorption of light by oxyhemoglobin. This NAD(P)H-based approach consistently identified over 95% of the total pool of erythrocytes and reticulocytes in bone marrow samples and revealed robust as over 93% of these two erythropoietic subsets were identified in melanoma tumor samples with the same method. The measurement of cellular endogenous NAD(P)H fluorescence, therefore, offers a reliable and straightforward alternative to identify erythrocytes and reticulocytes without additional immunostaining or the need to modify the cytometer's optical configuration. © 2018 International Society for Advancement of Cytometry.

Single-cell analyses identify bioengineered niches for enhanced maintenance of hematopoietic stem cells

The in vitro expansion of long-term hematopoietic stem cells (HSCs) remains a substantial challenge, largely because of our limited understanding of the mechanisms that control HSC fate choices. Using single-cell multigene expression analysis and time-lapse microscopy, here we define gene expression signatures and cell cycle hallmarks of murine HSCs and the earliest multipotent progenitors (MPPs), and analyze systematically single HSC fate choices in culture. Our analysis revealed twelve differentially expressed genes marking the quiescent HSC state, including four genes encoding cell–cell interaction signals in the niche. Under basal culture conditions, most HSCs rapidly commit to become early MPPs. In contrast, when we present ligands of the identified niche components such as JamC or Esam within artificial niches, HSC cycling is reduced and long-term multipotency in vivo is maintained. Our approach to bioengineer artificial niches should be useful in other stem cell systems.

Haematopoietic stem cell (HSC) self-renewal is not sufficiently understood to recapitulate in vitro. Here, the authors generate gene signature and cell cycle hallmarks of single murine HSCs, and use identified endothelial receptors Esam and JamC as substrates to enhance HSC growth in engineered niches.

Disturbance response indicators of Impatiens walleriana exposed to benzene and chromium

The purpose of this study was to evaluate the remediation potential and disturbance response indicators of Impatiens walleriana exposed to benzene and chromium. Numerous studies over the years have found abundant evidence of the carcinogenicity of benzene and chromium (VI) in humans. Benzene and chromium are two toxic industrial chemicals commonly found together at contaminated sites, and one of the most common management strategies employed in the recovery of sites contaminated by petroleum products and trace metals is in situ remediation. Given that increasing interest has focused on the use of plants as depollution agents, direct injection tests and benzene misting were performed on I. walleriana to evaluate the remediation potential of this species. I. walleriana accumulated hexavalent chromium, mainly in the root system (164.23 mg kg^-1), to the detriment of the aerial part (39.72 mg kg^-1), and presented visible damage only at the highest concentration (30 mg L^-1). Unlike chromium (VI), chromium (III) was retained almost entirely by the soil, leaving it available for removal by phytotechnology. However, after the contamination stopped, I. walleriana responded positively to the detoxification process, recovering its stem stiffness and leaf color. I. walleriana showed visible changes such as leaf chlorosis during the ten days of benzene contamination. When benzene is absorbed by the roots, it is translocated to and accumulated in the plant's aerial part. This mechanism the plant uses ensures its tolerance to the organic compound, enabling the species to survive and reproduce after treatment with benzene. Although I. walleriana accumulates minor amounts of hexavalent chromium in the aerial part, this amount suffices to induce greater oxidative stress and to increase the amount of hydrogen peroxide when compared to that of benzene. It was therefore concluded that I. walleriana is a species that possesses desirable characteristics for phytotechnology.

Serous cystic neoplasm of the pancreas: a multinational study of 2622 patients under the auspices of the International Association of Pancreatology and European Pancreatic Club (European Study Group on Cystic Tumors of the Pancreas)

OBJECTIVES

Serous cystic neoplasm (SCN) is a cystic neoplasm of the pancreas whose natural history is poorly known. The purpose of the study was to attempt to describe the natural history of SCN, including the specific mortality.

DESIGN

Retrospective multinational study including SCN diagnosed between 1990 and 2014.

RESULTS

2622 patients were included. Seventy-four per cent were women, and median age at diagnosis was 58 years (16-99). Patients presented with non-specific abdominal pain (27%), pancreaticobiliary symptoms (9%), diabetes mellitus (5%), other symptoms (4%) and/or were asymptomatic (61%). Fifty-two per cent of patients were operated on during the first year after diagnosis (median size: 40 mm (2-200)), 9% had resection beyond 1 year of follow-up (3 years (1-20), size at diagnosis: 25 mm (4-140)) and 39% had no surgery (3.6 years (1-23), 25.5 mm (1-200)). Surgical indications were (not exclusive) uncertain diagnosis (60%), symptoms (23%), size increase (12%), large size (6%) and adjacent organ compression (5%). In patients followed beyond 1 year (n=1271), size increased in 37% (growth rate: 4 mm/year), was stable in 57% and decreased in 6%. Three serous cystadenocarcinomas were recorded. Postoperative mortality was 0.6% (n=10), and SCN's related mortality was 0.1% (n=1).

CONCLUSIONS

After a 3-year follow-up, clinical relevant symptoms occurred in a very small proportion of patients and size slowly increased in less than half. Surgical treatment should be proposed only for diagnosis remaining uncertain after complete workup, significant and related symptoms or exceptionally when exists concern with malignancy. This study supports an initial conservative management in the majority of patients with SCN.

TRIAL REGISTRATION NUMBER

IRB 00006477.

Detection of glucose abnormalities in patients with acute coronary heart disease: study of reliable tools in clinical practice

AIM

To investigate the prevalence of glucose abnormalities in patients with acute coronary syndrome and to assess the reliability of certain clinical or analytical variables to predict a pathologic result of oral glucose tolerance test (OGTT) at 3 months from discharge.

SUBJECTS AND METHODS

Prospective study of 102 patients admitted to the coronary care units. Patients were classified according to the American Diabetes Association criteria. Three months after discharge, an OGTT was performed to non-diabetic patients.

RESULTS

Forty-six (45.1%) patients were identified as diabetic (5 previously undiagnosed) and 56 (54.9%) as non-diabetic. OGTT identified 22% of diabetes, 33% of impaired glucose tolerance, and 45% of normal glucose tolerance. Fasting glucose (r=0.55, p<0.001), glycated hemoglobin (HbA1c) (r=0.46, p<0.001), low HDL cholesterol (HDLc) levels (r=-0.34, p<0.02), waist-hip ratio (r=0.45, p<0.01), high systolic blood pressure (r=0.5, p<0.01), and presence of acute myocardial infarction (r=0.46, p<0.001) at admission resulted significant to predict a pathologic result of OGTT.

CONCLUSIONS

Glucose abnormalities are frequent in acute coronary syndrome patients. Certain clinical and analytical markers at admission such as fasting glucose, HbA1c, HDL-c<40 mg/dl, waist-hip ratio, and systolic blood pressure, are useful to recognize patients with a higher predisposition to present a pathologic result in OGTT at 3 months from discharge.

[Neuroprotection in Parkinson's disease: analysis though group of experts' methodology]

INTRODUCTION

Currently used antiparkinsonian drugs neither stop nor slow-down the progressive nature of the disease. The final phase of PD is characterized by the presence of symptoms and signs resistant to dopaminergic agents, such as depression, dementia, freezing and falls. Therefore, it is urgent to develop therapies able to positively modify this outcome. Despite neuroprotection is a research priority in PD, no effective strategies have been found so far.

METHOD

A key informants study was conducted. A group of experts in PD fulfilled a questionnaire of 10 questions to explore the most important topics related to neuroprotection. Afterwards a consensus about the current situation of neuroprotection in PD was established and future directions of development were suggested.

RESULTS

Most of the answers emphasized the need of new concepts, the limitations of animal models and the difficulties in the difficulties in demonstrating a neuroprotective effects in humans owing to a lack of biomarkers. Some of the experts believe that we are already exerting a disease modifying effect.

CONCLUSIONS

The concept of neuroprotection should be widened. Animal models should be improved. A reliable biomarker to start neuroprotective therapies long before the appearance of motor symptoms and to evaluate the neuroprotective effect of any therapy should be urgently developed.

Trace elements removal from water using modified activated carbon

This paper present the possible alternative options for the remove of trace elements from drinking water supplies in the trace. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causing various adverse effects on living bodies. The performance of three filter bed methods was evaluated in the laboratory. Experiments were conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe/Fe3C (iron/iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon, powder carbon steel and ceramic spheres in the ion-sorption columns as a cleaning process. The modified powdered block carbon is a satisfactory and economical sorbent for trace elements (arsenite and chromate) dissolved in water due to its low unit cost of about $23 and compatibility with the traditional household filtration system.

[Early alterations of adrenergic cardiac function in Parkinson's disease]

INTRODUCTION

Myocardial sympathetic (adrenergic) function is significantly affected in patients with idiopathic Parkinson's disease (PD) as is deduced from the cardiac scintigraphy evaluation with 123I-metaiodobenzylguanidine (123I-MIBG).

PATIENTS AND METHODS

In the present study, 60 patients with PD were studied compared to 17 normal subject without neurological disease. The clinical parameters evaluated were severity of the condition (measured by Hoehn and Yahr Scale), vegetative manifestations, development time and use and type of medication taken. Myocardial adrenergic function was analyzed by imaging with 123I-MIBG. Early (15 min) and delayed (4 h) images of the anterior view were obtained after injection of 123I-MIBG. Qualitative and semiquantitative 123I-MIBG uptake was quantified by calculating a heart-to-mediastinum (H/M) ratio.

RESULTS

We found a significant decrease of H/M ratio in patients with PD as compared with controls (p < 0.01) independently of development time, severity of the condition, use of medication or vegetative manifestations.

CONCLUSIONS

There is an important noradrenergic alteration in PD, that can be detected from early stages and does not exist in other parkinsonisms caused by a different pathogenic mechanism.

[123 I-MIBG myocardial sympathetic innervation scintigraphy and Parkinson's disease. Preliminary results]

OBJECTIVES

Cardiac sympathetic function in patients with Parkinson's disease (PD) is significantly impaired. Cardiac scintigraphy with 123I-metaiodobenzylguanidine (123I-MIBG) is used to assess cardiac sympathetic function.

METHODS

A total of 29 consecutive patients with PD and 10 control subjects without neurological disease were studied. Myocardial imaging with 123I-MIBG was performed to evaluate cardiac sympathetic function. Early and delayed images of the anterior view were obtained at 15 min. and 4 h. after injection of 123I-MIBG, respectively. 123I-MIBG uptake was quantified qualitatively and semiquantitatively by calculating a heart-to-mediastinum (H/M) ratio.

RESULTS

The heart/mediastinum ratio was markedly reduced in patients with PD (I to IV on the Hoehn and Yahr scale) when compared to the control subjects (p < 0.05). This finding was independent of the length and severity of the disease or the pharmacological treatment of the patients. None of the control subjects showed decrease in myocardial 123I-MIBG uptake.

CONCLUSIONS

Our findings indicate that a decrease in myocardial accumulation of 123I-MIBG was observed in the early stages of PD. This suggests that the measurement of 123I-MIBG may help the early diagnosis of PD, and can be used to detect cardiac autonomic dysfunction, especially in patients without typical signs and symptoms.

Chromate reduction in Serratia marcescens isolated from tannery effluent and potential application for bioremediation of chromate pollution

Pollution of aquatic systems by heavy metals has resulted in increasing environmental concern because they cannot be biodegraded. One metal that gives reason for concern due to its toxicity is chromium. Cr(VI) and Cr(III) are the principal forms of chromium found in natural waters. A chromate-resistant strain of the bacterium S. marcescens was isolated from tannery effluent. The strain was able to reduce Cr(VI) to Cr(III), and about 80% of chromate was removed from the medium. The reduction seems to occur on the cell surface. Transmission electron microscopic examination of cells revealed that particles were deposited on the outside of bacterial cells. A stable biofilm was formed in less than 10 h, reaching around 1010 cfu attached per milligram of activated carbon. These findings demonstrate that immobilized S. marcescens might be used in industrial waste treatment processes.

Taxonomic study of extreme halophilic archaea isolated from the "Salar de Atacama", Chile

A large number of halophilic bacteria were isolated in 1984-1992 from the Atacama Saltern (North of Chile). For this study 82 strains of extreme halophilic archaea were selected. The characterization was performed by using the phenotypic characters including morphological, physiological, biochemical, nutritional and antimicrobial susceptibility test. The results, together with those from reference strains, were subjected to numerical analysis, using the Simple Matching (S(SM)) coefficient and clustered by the unweighted pair group method of association (UPGMA). Fifteen phena were obtained at an 70% similarity level. The results obtained reveal a high diversity among the halophilic archaea isolated. Representative strains from the phena were chosen to determine their DNA base composition and the percentage of DNA-DNA similarity compared to reference strains. The 16S rRNA studies showed that some of these strains constitutes a new taxa of extreme halophilic archaea.

Compound odontoma--diagnosis and treatment: three case reports

Odontomas are the most common type of odontogenic tumors and generally they are asymptomatic. This paper describes three cases of compound odontomas diagnosed in children due to dislodgement or over-retention of primary anterior teeth and/or swelling of the cortical bone. In all cases, the surgical excision of the lesions was performed and, in one case, orthodontic treatment was adopted in order to move an impacted permanent tooth to its normal position. The results achieved indicate that the early diagnosis of odontomas allows the adoption of a less complex and expensive treatment and ensures better prognosis.

Hereditary gingival fibromatosis: review of the literature and a case report

Hereditary gingival fibromatosis is a proliferative fibrous lesion of the gingival tissue that causes esthetic and functional problems. Both genetically and pharmacologically induced forms of gingival fibromatosis exist. This paper reports a case of severe generalized hereditary gingival fibromatosis in a 5-year-old girl. Treatment consisted of surgical removal of the hyperplastic fibrous tissue in a series of conventional gingivectomies. Postoperative examination 36 months after the final procedure revealed no signs of recurrence.

Co-occurrence of non-toxic (cyanopeptolin) and toxic (microcystin) peptides in a bloom of Microcystis sp. from a Chilean lake

A cyanobacterial bloom occurring in 1998 in lake Tres Pascualas (Concepción/Chile) was found to be dominated by Microcystis sp. The bloom contained both non-toxic (cyanopeptolin-type) and hepatotoxic (microcystin-type) peptides. Cyanopeptolin structure of the non-toxic peptides (called cyanopeptolin VW-1 and VW-2, respectively) was revealed by matrix assisted laser desorption ionization mass spectrometry (MALDI-TOF-MS) of whole cells, showing dominant molecular ions at m/z = 975 and m/z 995, respectively. On post source decay (PSD), both cyanopeptolins showed fragments deriving from Ahp-Phe-MTyr (3-amino-6-hydroxy-2-piperidone), the characteristic partial structure of cyanopeptolins. The amounts of each of the two cyanopeptolins could only roughly be estimated to be >0.1% of bloom material dry weight. In addition the blooms contained microcystins (20 microg/g bloom dry weight as determined by RP-HPLC, 13 microg/g according to ELISA determination). MALDI-TOF-MS revealed several structural variants of microcystin: MCYST-RR (microcystin with Arg and Arg, indicated by m/z 1,038 and confirmed by PSD revealing a m/z = 135 fragment deriving from the Adda side chain, MCYST-FR (microcystin with Phe and Arg, indicated by m/z = 1,015). The presence of [Asp(3)]-MCYST-LR (microcystin with Leu and Arg, Asp non-methylated, indicated by m/z 981), and [Asp(3)]-MCYST-YR (microcystin with Tyr and Arg, Asp non-methylated, indicated by m/z 1,031) were likely. The relative amounts of the peptides varied between February, April, and May. Whole cell extracts from the bloom material revealed specific enzyme inhibitory activities. The serin-proteases trypsin, plasmin, elastase were inhibited, assumable due to the cyanopeptolins found. Elastase and the cysteine-protease papain were not inhibited, inhibitions of protein kinase and glutathione S-transferase (GST) were low. Strong inhibition was observed with protein-phosphatase-1, likely due to the microcystins present in the samples.

[Total arterial myocardial revascularization with both mammary arteries without extracorporeal circulation]

INTRODUCTION

Tector has described the off-pump total arterial revascularization technique, using multiple anastomosis with both internal thoracic arteries. To reduce surgical morbid-mortality, we have proposed the use of this technique without extracorporeal circulation.

PATIENTS AND METHODS

From April, 1998 the off-pump <<Tector>> technique was performed in 92 patients, 74 male (80%) and 18 female (20%), with a mean age of 64.9+/-8.1 years (42-78). Preoperative angiography demonstrated triple-vessel disease in 58 (63%) patients, and left main disease was present in 19 (20.5%) patients. Forty patients (43.5%) showed unstable angina, 24 patients (26%) significant peripheral vascular disease, and 26 (28%) diabetes mellitus. Both internal thoracic arteries were harvested using the skeletonization technique and were used like a <<T or T>> graft. The flow in the graft was measured using a flowmeter, and in 24 (26%) patients by angiographic study.

RESULTS

A total of 274 distal anastomoses were performed, 122 (44.6%) in the lateral or inferior wall, and 69 (25.2%) were sequential, with an average of 2.98 bypass/patient. In 59.8% of the patients a triple bypass was performed, 22% double bypass, 17% cuadruple bypass and 1 patient a quintuple bypass. During the initial six hours 64.9% of patients were extubated. Only one patient (1.1%) needed intraaortic ballon pumping and 3 (3.2%) inotropics during the postoperative course. Hospital mortality was 3 (3.2%) patients. Reoperation for bleeding was needed in just one patient (1.1%), and 78.3% of patients were not transfused. Mediastinitis occurred in 3 patients (3.2%). Postoperative stroke was not observed. At 7.7+/-2.8 months of mean follow-up all patients were free of symptoms and the global patency rate of 94%.

CONCLUSIONS

Off-pump Tector technique appears to be safe, offering a complete arterial revascularization and showing a reduction of surgical morbidity.

Microcystin in cyanobacterial blooms in a Chilean lake

Cyanobacterial blooms dominated by Microcystis sp. occurred in lake Rocuant ("marisma", near Concepción/Chile) in February 1995 and 1996. In the bloom samples collected in both years the hepatotoxin microcystin was detected by RP-HPLC in both samples and in the sample of 1995 also by a toxicity assay using primary rat hepatocytes. In the bloom of 1995, the microcystin content of the dry bloom biomass was determined to be 130 micrograms/g on the basis of the RP-HPLC peak area and 800 micrograms/g on the basis of the rat hepatotoxicity assay, respectively. In the bloom of 1996, RP-HPLC analysis revealed a microcystin content of 8.13 micrograms/g bloom material dry weight. In this year no hepatotoxicity was measured using a concentration range up to 0.8 mg (d. w.) of bloom material per ml in the rat hepatotoxicity assay. This is the first report on the detection of microcystins in Chilean water bodies.

Is the femoral cannulation for minimally invasive aortic valve replacement necessary?

INTRODUCTION

Minimally invasive cardiac surgery through a small transverse sternotomy is a new promising technique that can be considered an alternative in most cases to aortic valve replacement thus reducing surgical trauma and subsequent time of hospitalization. The need to avoid the risks associated with femoro-femoral bypass has lead to the interest in aortic valve replacement (AVR) operations without femoral vessels cannulation. We want to emphasize a few important points of our technique, which differs somewhat from the one applied by Cosgrove and associates.

OBJECTIVE

This study details the approach to the minimally invasive AVR as first described by. Cosgrove et al. without standard femoral cannulation and points out our preliminary clinical experience.

PATIENTS AND METHODS

From October 1996 to May 1997 we have operated on 25 patients using minimally invasive AVR (MI-AVR) In 23 cases, access through transverse sternotomy as described by Cosgrove et al., was performed. In two additional cases the chest is opened via a mini-median sternotomy with an 'L'-shape extending from the sternal notch to the superior edge of the third interspace. Twenty-three patients underwent AVR through transverse sternotomy. The male/female ratio was 13:10. The mean age was 67 years (range 45-78 years). Seventy-four percent of the patients were over 65. Predominantly, in 43% of cases aortic valve stenosis and in 25% of cases aortic valve regurgitation isolated is presented. In 19 cases, a 10-cm transverse incision is performed over the second interspace. Likewise, in four cases over the third interspace according to the thorax morphology and length of the ascending aorta assessed by chest X-ray films. By convention, cannulation of the ascending aorta and right atrial appendage was performed as usual. In contrast, in one patient (5.5%), cannulation was placed in the superior vena cava and right common femoral vein into the inferior vena cava. In the present series, 15 mechanical prostheses and eight bioprostheses whose used sizes were 19, 21,23, and 25 mm in diameter were placed in four, nine, nine, and one of the cases, respectively. All patients underwent AVR electively and a transesophageal echocardiography probe is made.

RESULTS

During surgery, conversion to median sternotomy was not required in any patient. Mean aortic cross-clamp time was 68 min (range 38-90 min). Mean total bypass time was 87 min (range 50-120 min). Mean postoperative bleeding was 434 ml. (range 200-850 ml). Perioperative blood transfusion was required in 17% of the patients. Mean mechanical ventilation time was 7.3 h (range 3-24 h), with a mean ICU stay of 18 h. Mean postoperative hospital stay was 4.5 days (range 3-10 days). In all cases, transthoracic and transesophageal echocardiography were performed postoperatively Prosthetic valve dysfunction was not observed. On the other hand, just one patient (4%) died 5 days after operation due to sudden cardiac death. Further, in two patients (8%), during follow-up, pericardial effusion is detected. In one case, cardiac tamponade with hemodynamic instability required a pericardial window procedure. In addition, in two patients (8%), non-infectious sternal dehiscence required reinforced sternal closure.

CONCLUSIONS

Minimally invasive AVR surgery without femoral vessel cannulation is a safe procedure with less surgical aggression. After a learning curve, benefits on fast-track programs will be accomplished.

[Coronary surgery without extracorporeal circulation: 5-year experience]

INTRODUCTION

Coronary surgery without extracorporeal circulation is now an accepted technique of myocardial revascularization. A progressive increase in operations has recently been observed.

OBJECTIVE

We report our total experience with this technique in a consecutive series of patients operated on since 1991. This series is compared with other series of patients who underwent coronary surgery using cardiopulmonary bypass.

PATIENTS AND METHODS

From December 1991 to July 1996, thirty patients underwent myocardial revascularization without cardiopulmonary bypass through median sternotomy at our institution. This group was retrospectively compared with 22 patients who received isolated coronary artery bypass grafting with cardiopulmonary bypass (excluding reoperations) during the same period of time.

RESULTS

There were two hospital deaths and one case of myocardial infarction during the early postoperative period which required urgent reintervention. There were two variables showing a statistically significant difference between the groups with and without cardiopulmonary bypass. Incidence of non-fatal preoperative myocardial infarction increased (53% vs 23%), whereas minor mechanical ventilation time was reported (7 +/- 5 vs 14 +/- 9 h) in the group without cardiopulmonary bypass. Follow-up (1 to 55 months after operation, mean 29 months) was completed. There were no cardiac-related deaths. No return of angina nor any new myocardial infarctions were recorded. New myocardial revascularizations were not necessary.

CONCLUSIONS

Myocardial revascularization without extracorporeal circulation obtained good results that were similar to conventional procedures and were cost-effective.

Comparison between the polypeptide profile of halophilic bacteria and salt tolerant plants

Changes in the polypeptide profile induced by salt stress in halotolerant and halophilic bacteria, isolated from the Atacama desert (northern Chile), were compared with those in the cotyledons of Prosopis chilensis (Leguminoseae) seedlings, a salt tolerant plant. SDS-PAGE analyses show the presence of four predominant polypeptides, with molecular weights around 78, 70, 60 and 44 kDa respectively, both in bacteria and in cotyledons from P. chilensis seedlings raised under salt stress conditions. Moreover, the 60 and 44 kDa polypeptides seem to be salt responsive, since their concentration increases with increasing NaCl in the growth medium. Our results suggest a common mechanism for salt tolerance in prokaryotes and in eukaryotes.

Production of extracellular xylanases by Penicillium janthinellum. Effect of selected growth conditions

Xylanase production by Penicillium janthinellum using 10-100 mM of 2,2-dimethylsuccinate (DMS) buffer, in a range of pH 4.5-6.0 was studied. The enzyme activity was enhanced using oat xylan as the carbon source. Under these conditions a culture produced 1.14 mumol/min (11.4 U/mL or 84.4 U/mg) of beta-xylanase after 5 d of growth in a 10-mM buffer solution at pH 4.5. Protease was absent in the DMS buffer except when 100 mM phosphate buffer at pH 6.0 was used (4 U/mL). beta-Xylosidase was only found at a pH of 4.5 in all the buffer concentrations. At a 50 mM DMS buffer concentration at pH 4.5 beta-xylanases were induced by both oat and birch xylans, having a greater effect with oat spelt xylans. Electrophoretic analyses showed that the birchwood xylan induction exhibited different proteins profiles. No beta-xylosidase or beta-glucosidase was induced until d 5. The beta-xylanases were rapidly inactivated at 50 degrees C, however, birch xylanase appeared to be more stable than oat xylanase. Using oat xylan as an inductor, the beta-xylosidase and beta-glucosidase were 85 and 91 U/L, respectively, on d 7. The xylanase produced by induction from sugar cane bagasse hydrolyzate was used for pulp biobleaching. A 20% decrease on the Kappa value in Kraft pulp using the culture extract was obtained. These selective growth conditions led us to modulate the xylanase production for pulp delignification.

Numerical taxonomy of moderately halophilic gram-positive cocci isolated from the Salar de Atacama (Chile)

A taxonomic study has been carried out on 22 strains of moderately halophilic motile cocci isolated from the Salar de Atacama (Chile). The 112 phenotypic tests were analyzed by numerical taxonomy using SSM coefficient and the unweighted pair group method of association (UPGMA). At the 67% similarity level, two phenons were obtained: phenon A included 11 strains and phenon B, 11 strains too, whereas the six reference strains did not cluster within these two phenons. These results suggest that moderately halophilic cocci with different phenotypic characteristics from previously described species can be isolated from the hypersaline habitat Salar de Atacama.