El puntaje de Framingham ayudaría en la estratificación del riesgo de pacientes con ergometría positiva y SPECT normal / The Framingham score could help in risk stratification of patients with positive ergometry and normal SPECT

Antecedentes. El valor pronóstico de una ergometría positiva en el contexto de imágenes tomográficas de perfusión miocárdica de estrés y reposo (SPECT) normales no está bien establecido. Objetivos. Documentar la incidencia de infarto, muerte y revascularización coronaria en pacientes con una ergometría positiva de riesgo intermedio e imágenes de perfusión SPECT normales, y explorar el potencial valor del puntaje de riesgo de Framingham en la estratificación pronóstica de estos pacientes. Métodos. Cohorte retrospectiva integrada por pacientes que habían presentado síntomas o hallazgos electrocardiográficos compatibles con enfermedad arterial coronaria durante la prueba de esfuerzo, con criterios de riesgo intermedio en la puntuación de Duke y perfusión miocárdica SPECT normal. Fueron identificados a partir de la base de datos del laboratorio de cardiología nuclear del Instituto de Cardiología y Cirugía Cardiovascular de la ciudad de Posadas, Argentina. Resultados. Fueron elegibles 217 pacientes. El seguimiento fue de 3 1,5 años. La sobrevida libre de eventos (muerte,infarto de miocardio no fatal, angioplastia coronaria o cirugía de bypass de arteria coronaria) a uno, tres y cinco años fue significativamente menor (Log-rank test, p= 0,001) en el grupo con puntaje de Framingham alto o muy alto (77, 71y 59 %, respectivamente) que en el grupo de puntaje bajo o intermedio (89, 87 y 83 %). Tomando como referencia a los pacientes con riesgo bajo en el puntaje de Framingham, luego de ajustar por edad, sexo y puntaje de Duke, los pacientes categorizados en los estratos alto y muy alto riesgo del puntaje de Framingham presentaron una incidencia del evento combinado cercana al triple (hazard ratio [HR] 2,81; intervalo de confianza [IC] del 95 % 0,91 a 8,72; p= 0,07 y HR 3,61;IC 95 % 1,23 a 10,56; p= 0,019 respectivamente). Conclusiones. La estimación de riesgo con el puntaje de Framingham sería de ayuda en la estratificación pronóstica de los pacientes con ergometría positiva y SPECT normal. (AU)

Background. The prognostic value of positive exercise testing with normal SPECT myocardial perfusion imaging is not well established. Objectives. To document the incidence of infarction, death, and coronary revascularization in patients with a positive intermediate-risk exercise test and normal SPECT perfusion images and to explore the potential value of the Framingham Risk Score in the prognostic stratification of these patients. Methods. A retrospective cohort comprised patients who presented symptoms or electrocardiographic findings compatible with coronary artery disease during the stress test, with intermediate risk criteria in the Duke score and normal SPECT myocardial perfusion. They were identified from the database of the nuclear cardiology laboratory of the Instituto de Cardiología y Cirugía Cardiovascular of Posadas, Argentina. Results. 217 patients were eligible. Follow-up was 3 1.5 years. Event-free survival (death, non-fatal myocardial infarction, coronary angioplasty, or coronary artery bypass surgery) at one, three, and five years was significantly lower (Log-ranktest, p: 0.001) in the group with a score of Framingham high or very high (77, 71 and 59 %, respectively) than in the lowor intermediate score group (89, 87 and 83 %). Taking as reference the low-risk patients in the Framingham score, after adjusting for age, sex, and Duke score, the patients categorized in the high-risk and very high-risk strata showed about three times higher incidence of the combined event (hazard ratio [HR] 2.81; 95 % confidence interval [CI] 0.91 to 8.72;p=0.07 and HR 3.61; 95 % CI 1.23 to 10.56; p=0.019 respectively). Conclusions. Risk estimation with the Framingham score would be helpful in the prognostic stratification of patients with positive exercise testing and normal SPECT. (AU)

El dilema clínico frente a los pacientes con ergometría positiva y prueba de perfusión miocárdica con SPECT normal / The clinical dilemma facing patients with positive stress test and normal SPECT myocardial perfusion imaging

La evaluación de la perfusión miocárdica con SPECT combina una prueba de esfuerzo (ergometría o estrés farmacológico) junto a imágenes de perfusión con radioisótopos. Este estudio es útil para establecer el diagnóstico de enfermedad arterial coronaria, estratificar el riesgo de infarto y tomar decisiones terapéuticas. Un resultado normal aporta un alto valor predictivo negativo, es decir, una muy baja probabilidad de que el paciente presente eventos cardiovasculares. El hallazgo de signos de isquemia en la ergometría podría poner en jaque el valor predictivo negativo de una perfusión normal. En presencia de este resultado, el paso siguiente es evaluar los predictores de riesgo en la ergometría, el riesgo propio del paciente en función de los antecedentes clínicos y el puntaje cálcico coronario, cuando este se encuentra disponible. Ante la presencia concomitante de otros marcadores de riesgo se sugiere completar la evaluación con un estudio anatómico.El uso de nuevas tecnologías podría mejorar la precisión en la predicción de eventos. (AU)

Assessment of myocardial perfusion with SPECT combines a stress test (ergometry or pharmacological stress) with radioisotope perfusion imaging. This test is helpful to diagnose coronary artery disease, stratify the risk of heart attack, and make therapeutic decisions. A normal result provides a high negative predictive value; therefore, the probability of cardiovascular events is very low. Signs of ischemia on an ergometry could jeopardize the negative predictive value of normal perfusion. In this clinical setting, the next step is to evaluate the risk predictors in the stress test, the individual risk based on the clinical history, and the coronary calcium score when available. Given the simultaneous presence of other risk markers,completing the evaluation with an anatomical study is suggested. The use of new technologies could improve the accuracy of event prediction. (AU)

Cardiovascular Risk and Statin Eligibility of Young Adults After an MI: Partners YOUNG-MI Registry.

BACKGROUND: Despite significant progress in primary prevention, the rate of MI has not declined in young adults. OBJECTIVES: The purpose of this study was to evaluate statin eligibility based on the 2013 American College of Cardiology/American Heart Association guidelines for treatment of blood cholesterol and 2016 U.S. Preventive Services Task Force recommendations for statin use in primary prevention in a cohort of adults who experienced a first-time myocardial infarction (MI) at a young age. METHODS: The YOUNG-MI registry is a retrospective cohort from 2 large academic centers, which includes patients who experienced an MI at age ≤50 years. Diagnosis of type 1 MI was adjudicated by study physicians. Pooled cohort risk equations were used to estimate atherosclerotic cardiovascular disease risk score based on data available prior to MI or at the time of presentation. RESULTS: Of 1,685 patients meeting inclusion criteria, 210 (12.5%) were on statin therapy prior to MI and were excluded. Among the remaining 1,475 individuals, the median age was 45 years, there were 294 (20%) women, and 846 (57%) had ST-segment elevation MI. At least 1 cardiovascular risk factor was present in 1,225 (83%) patients. The median 10-year atherosclerotic cardiovascular disease risk score of the cohort was 4.8% (interquartile range: 2.8% to 8.0%). Only 724 (49%) and 430 (29%) would have met criteria for statin eligibility per the 2013 American College of Cardiology/American Heart Association guidelines and 2016 U.S. Preventive Services Task Force recommendations, respectively. This finding was even more pronounced in women, in whom 184 (63%) were not eligible for statins by either guideline, compared with 549 (46%) men (p < 0.001). CONCLUSIONS: The vast majority of adults who present with an MI at a young age would not have met current guideline-based treatment thresholds for statin therapy prior to their MI. These findings highlight the need for better risk assessment tools among young adults.

[Incidence and risk factors of endoleak in endovascular aortic aneurysm repair]. / Incidencia y factores de riesgo de endofugas en el tratamiento endovascular de los aneurismas aórticos.

BACKGROUND: endovascular aneurysm repair (EVAR) reduces morbidity and hospital stay compaired with open surgical repair. Endoleak is a common complication of the procedure. The resulting increase of pressure within the sac may expand the aneurysm with the following risk of rupture. The aim of this study was to recognize the incidence of endoleak in tomographic controls of the patients who underwent endovascular repair at our hospital as well as identify the risk factors associated with this complication. METHODS: all consecutive patients who underwent endovascular aneurysm repair at our hospital between 2008, February until 2012, February were restrospectively enrolled in the study, excluding those who were lost at follow-up. 43 patients were included, aged 70.5 ± 6 (men: 88%). The endpoint was endoleak incidence at 1, 6, 12th months after the intervention in the control tomography, and its association with underlying risk factors: hypertension, Smoking, chronic obstructive pulmonary desease and the diameter of the aneurysm. RESULTS: eleven (11%) patients developed endoleak (type I 9%, type III 2%). All were infrarrenal aortic aneurysms. The anteroposterior diameter of the aneurysm (more than 60 mm) showed a trend toward statistical significance as a risk factor (30% vs. 6%; p:0.073). No relationship was found with gender, age, COPD, smoking or hypertension. CONCLUSION: endoleak after endovascular aneurysm repair is a common complication. The size of the aneurysm might be a risk factor of the event.

Introducción: La reparación endovascular de la patología aneurismática de la aorta ha permitido una disminución de la morbilidad y una recuperación más precoz con respecto a la cirugía convencional. Entre las complicaciones más frecuentes del procedimiento se encuentra la endofuga, cuyo principal riesgo es el aumento de la presión dentro del saco aneurismático y rotura del aneurisma. El objetivo de este estudio es evaluar la incidencia global de endofugas en los controles tomográficos de los pacientes tratados mediante reparación aórtica endovascular en la institución y reconocer los factores de riesgo que predicen su presentación. Materiales y Métodos: En un diseño retrospectivo se incluyeron todos los pacientes (N: 43, hombres 88%) tratados por reparacion endovascular entre febrero de 2008 y febrero de 2012 (4 años), con seguimiento clínico y tomográfico en la institución. La edad promedio fue de 70,5 ± 6 años. El evento primario evaluado fue la presentación de endofugas en la tomografía computada de control a 1, 6 y 12 meses posteriores al procedimiento, y su asociación a distintos factores predisponentes: hipertensión arterial, tabaquismo, enfermedad pulmonar obstructiva crónica y diámetro del aneurisma. Resultados: La incidencia global de endofugas fue del 11% (9% tipo I y 2% tipo III), todas en aneurismas abdominales infrarrenales. Hubo tendencia a la significación, como factor de riesgo predisponente, en el diámetro de aneurisma mayor de 60 mm (30% vs. 6%; p:0,073), mientras que los demás factores analizados no presentaron relación con la complicación. Conclusión: La endofuga luego de la reparación endovascular de la aorta es frecuente. El diametro del aneurisma puede ser un factor predisponente para este tipo de complicación.

Incidencia y factores de riesgo de endofugas en el tratamiento endovascular de los aneurismas aórticos / [Incidence and risk factors of endoleak in endovascular aortic aneurysm repair].

BACKGROUND: endovascular aneurysm repair (EVAR) reduces morbidity and hospital stay compaired with open surgical repair. Endoleak is a common complication of the procedure. The resulting increase of pressure within the sac may expand the aneurysm with the following risk of rupture. The aim of this study was to recognize the incidence of endoleak in tomographic controls of the patients who underwent endovascular repair at our hospital as well as identify the risk factors associated with this complication. METHODS: all consecutive patients who underwent endovascular aneurysm repair at our hospital between 2008, February until 2012, February were restrospectively enrolled in the study, excluding those who were lost at follow-up. 43 patients were included, aged 70.5 ± 6 (men: 88

). The endpoint was endoleak incidence at 1, 6, 12th months after the intervention in the control tomography, and its association with underlying risk factors: hypertension, Smoking, chronic obstructive pulmonary desease and the diameter of the aneurysm. RESULTS: eleven (11

). All were infrarrenal aortic aneurysms. The anteroposterior diameter of the aneurysm (more than 60 mm) showed a trend toward statistical significance as a risk factor (30

; p:0.073). No relationship was found with gender, age, COPD, smoking or hypertension. CONCLUSION: endoleak after endovascular aneurysm repair is a common complication. The size of the aneurysm might be a risk factor of the event.

Incidencia y factores de riesgo de endofugas en el tratamiento endovascular de los aneurismas aórticos. / [Incidence and risk factors of endoleak in endovascular aortic aneurysm repair].

BACKGROUND: endovascular aneurysm repair (EVAR) reduces morbidity and hospital stay compaired with open surgical repair. Endoleak is a common complication of the procedure. The resulting increase of pressure within the sac may expand the aneurysm with the following risk of rupture. The aim of this study was to recognize the incidence of endoleak in tomographic controls of the patients who underwent endovascular repair at our hospital as well as identify the risk factors associated with this complication. METHODS: all consecutive patients who underwent endovascular aneurysm repair at our hospital between 2008, February until 2012, February were restrospectively enrolled in the study, excluding those who were lost at follow-up. 43 patients were included, aged 70.5 ± 6 (men: 88

). The endpoint was endoleak incidence at 1, 6, 12th months after the intervention in the control tomography, and its association with underlying risk factors: hypertension, Smoking, chronic obstructive pulmonary desease and the diameter of the aneurysm. RESULTS: eleven (11

) patients developed endoleak (type I 9

, type III 2

). All were infrarrenal aortic aneurysms. The anteroposterior diameter of the aneurysm (more than 60 mm) showed a trend toward statistical significance as a risk factor (30

vs. 6

; p:0.073). No relationship was found with gender, age, COPD, smoking or hypertension. CONCLUSION: endoleak after endovascular aneurysm repair is a common complication. The size of the aneurysm might be a risk factor of the event.

Hydroxylation of recombinant human collagen type I alpha 1 in transgenic maize co-expressed with a recombinant human prolyl 4-hydroxylase.

BACKGROUND: Collagens require the hydroxylation of proline (Pro) residues in their triple-helical domain repeating sequence Xaa-Pro-Gly to function properly as a main structural component of the extracellular matrix in animals at physiologically relevant conditions. The regioselective proline hydroxylation is catalyzed by a specific prolyl 4-hydroxylase (P4H) as a posttranslational processing step. RESULTS: A recombinant human collagen type I α-1 (rCIα1) with high percentage of hydroxylated prolines (Hyp) was produced in transgenic maize seeds when co-expressed with both the α- and ß- subunits of a recombinant human P4H (rP4H). Germ-specific expression of rCIα1 using maize globulin-1 gene promoter resulted in an average yield of 12 mg/kg seed for the full-length rCIα1 in seeds without co-expression of rP4H and 4 mg/kg seed for the rCIα1 (rCIα1-OH) in seeds with co-expression of rP4H. High-resolution mass spectrometry (HRMS) analysis revealed that nearly half of the collagenous repeating triplets in rCIα1 isolated from rP4H co-expressing maize line had the Pro residues changed to Hyp residues. The HRMS analysis determined the Hyp content of maize-derived rCIα1-OH as 18.11%, which is comparable to the Hyp level of yeast-derived rCIα1-OH (17.47%) and the native human CIa1 (14.59%), respectively. The increased Hyp percentage was correlated with a markedly enhanced thermal stability of maize-derived rCIα1-OH when compared to the non-hydroxylated rCIα1. CONCLUSIONS: This work shows that maize has potential to produce adequately modified exogenous proteins with mammalian-like post-translational modifications that may be require for their use as pharmaceutical and industrial products.

Laparoscopic transperitoneal and retroperitoneal nephrectomies in children: a change of practice.

INTRODUCTION: Laparoscopic nephrectomies (LNs) may be performed in children with benign renal disease by the transperitoneal (TP) or retroperitoneal (RP) approach. OBJECTIVES: The aim of this study was to present our early results from using both the laparoscopic transperitoneal and retroperitoneal approach, highlighting the change in the approach to a better, simpler procedure performed by experienced surgeons. MATERIALS AND METHODS: Between February 2002 and June 2006, 30 LNs were performed, with the first 10 patients by TP (group 1) and the remaining patients by RP (group 2). Two patients were not included. Demographic data were compared: mean age (88 vs. 66.6 months), gender (30% female vs. 70% male), and laterality (60% left-handed vs. 40% right-handed). Other factors were assessed, as well: Operating time was compared, as was morbidity, analgesics requirement, postoperative hospital stay, and time to resume oral intake. RESULTS: LN was performed in 28 of the 30 cases. One case in each group was converted. Both groups were similar regarding operating time (TP: 92.2 minutes vs. RP: 121.1), hospital stay (36.5 hours vs. 28.8), postoperative analgesia (2.1 doses of dipyrone and 1.2 doses of nalbuphine vs. 2.3 and 1.4). RP was associated with significantly faster postoperative analgesia tolerance than that of the TP approach (7.8 hours vs. 14.4; P < 0.05). Two (22.2%) patients in group 1 presented with vomiting, whereas no patients in group 2 had postoperative vomiting (P < 0.05). No further postoperative complications appeared. CONCLUSIONS: In our hands, both laparoscopic TP and RP approaches are equally safe and effective, but the operating time was slightly shorter (not significant) and postoperative recovery significantly longer for TP. LN may be performed by both approaches, obtaining equal efficacy. TP may be associated with minimal paralytic ileus within the first 12-24 hours, meanwhile RP is related with better surgical skill and postoperative tolerance.

Production of a recombinant full-length collagen type I alpha-1 and of a 45-kDa collagen type I alpha-1 fragment in barley seeds.

Recombinant DNA technology can be used to design and express collagen and gelatin-related proteins with predetermined composition and structure. Barley seed was chosen as a production host for a recombinant full-length collagen type I alpha1 (rCIa1) and a related 45-kDa rCIa1 fragment. The transgenic barley seeds were shown to accumulate both the rCIa1 and the 45-kDa rCIa1 fragment. Even when the amount of the rCIa1 was just above the detection threshold, this work using rCIa1 as a model demonstrated for the first time that barley seed can be used as a production system for collagen-related structural proteins. The 45-kDa rCI1a fragment expression, targeted to the endoplasmic reticulum, was controlled by three different promoters (a constitutive maize ubiquitin, seed endosperm-specific rice glutelin and germination-specific barley alpha-amylase fusion) to compare their effects on rCIa1 accumulation. Highest accumulation of the 45-kDa rCIa1 was obtained with the glutelin promoter (140 mg/kg seed), whereas the lowest accumulation was obtained with the alpha-amylase promoter. To induce homozygosity for stable 45-kDa rCIa1 production in the transgenic lines, doubled haploid (DH) progeny was generated through microspore culture. The 45-kDa rCIa1 expression levels achieved from the best DH lines were 13 mg/kg dry seeds under the ubiquitin promoter and 45 mg/kg dry seeds under the glutelin promoter. Mass spectroscopy and amino acid composition analysis of the purified 45-kDa rCIa1 fragment revealed that a small percent of prolines were hydroxylated with no additional detectable post-translational modifications.

Purification and characterization of a transgenic corn grain-derived recombinant collagen type I alpha 1.

Corn offers advantages as a transgenic host for producing recombinant proteins required at large volumes (1,000's of tons per year) and low cost (less than US$50/kg) by generating them as co-products of biorefining. We describe the purification and characterization of a corn grain-derived mammalian structural protein having such market characteristics: a full length recombinant collagen type I alpha 1 (rCI alpha 1) chain. Material properties of interest are gelation behavior, which would depend on as yet unverified ability of corn to carry out post-translational prolyl hydroxylation and formation of triple helical conformation. The starting material was grain where the expression of rCI alpha 1 had been directed by an embryo-specific promoter. Purification consisted of extraction at low pH followed by membrane and chromatographic steps to isolate rCI alpha 1 for characterization. The amino acid composition and immunoreactivity of CI alpha 1 was similar to that of an analogous native human CI alpha 1 and to rCI alpha 1 produced by the yeast Pichia pastoris. Tandem mass spectrometry confirmed the primary sequence of the corn-derived rCI alpha 1 with 46% coverage. Fragments of the rCI alpha 1 chains were also observed, possibly caused by endogenous plant proteases. The corn-derived rCI alpha 1 had a low level of prolyl hydroxylation (approximately 1% versus 11%) relative to animal-derived CI alpha 1 and folded into its characteristic triple-helical structure as indicated by its resistance to pepsin digestion below its melting temperature of 26(o)C. The 29 amino acid foldon fused to the C-terminus to initiate triple helix formation was not cleaved from the rCI alpha 1 chains, but could be removed by pepsin treatment.

Purification and characterization of a 44-kDa recombinant collagen I alpha 1 fragment from corn grain.

This paper demonstrates that a fibrous, repetitive amino acid sequence collagen-related protein, a 44-kDa fragment of human collagen I alpha 1 (CIalpha1), was expressed in corn grain molecularly equivalent to that produced in recombinant yeast. The recombinant CIalpha1 was extracted and purified from early generation plants having low levels of recombinant protein accumulation. It was selectively extracted at low pH and purified by ion exchange and gel filtration chromatography, resulting in a 44-kDa CIalpha1 with >70% purity and 60% recovery. The N-terminal sequence, amino acid composition, and immunoreactivity closely matched those of an analogous 44-kDa CIalpha1 fragment produced by the yeast Pichia . The corn-derived 44-kDa CIalpha1 had an intact protein mass of 44088 Da, which is within 0.2% of the mass calculated from the expected sequence. Tandem mass spectrometry confirmed the primary sequence with 78% coverage. The amino acid composition analysis indicated a low level of prolyl hydroxylation. Glycoprotein staining revealed no glycosylation.

Recombinant microbial systems for the production of human collagen and gelatin.

The use of genetically engineered microorganisms is a cost-effective, scalable technology for the production of recombinant human collagen (rhC) and recombinant gelatin (rG). This review will discuss the use of yeast (Pichia pastoris, Saccharomyces cerevisiae, Hansenula polymorpha) and of bacteria (Escherichia coli, Bacillus brevis) genetically engineered for the production of rhC and rG. P. pastoris is the preferred production system for rhC and rG. Recombinant strains of P. pastoris accumulate properly hydroxylated triple helical rhC intracellularly at levels up to 1.5 g/l. Coexpression of recombinant collagen with recombinant prolyl hydroxylase results in the synthesis of hydroxylated collagen with thermal stability similar to native collagens. The purified hydroxylated rhC forms fibrils that are structurally similar to fibrils assembled from native collagen. These qualities make rhC attractive for use in many medical applications. P. pastoris can also be engineered to secrete high levels (3 to 14 g/l ) of collagen fragments with defined length, composition, and physiochemical properties that serve as substitutes for animal-derived gelatins. The replacement of animal-derived collagen and gelatin with rhC and rG will result in products with improved safety, traceability, reproducibility, and quality. In addition, the rhC and rG can be engineered to improve the performance of products containing these biomaterials.

Cutaneous tuberculosis diagnosis in an inhospitable Amazonian region by means of telemedicine and molecular biology.

We report on a 13-year-old boy who displayed a chronic granulomatous inflammatory reaction of 5 years duration. The lesion was resistant to different antibiotic schemes; his routine laboratory tests and chest radiographs were normal. Teledermatologic consultation and histopathologic study of skin biopsy suggested scrofulodermal tuberculosis. Polymerase chain reaction amplification of DNA extracted from lymph node biopsy was taken as starting material for dot-blot hybridization using Mtp-40 and IS 6110 as probes for detecting either Mycobacterium tuberculosis or any mycobacteria belonging to the M tuberculosis complex, respectively. Positive results in both hybridizations were further confirmed by culturing in BACTEC MGIT 960 system. The lesion greatly diminished following isoniazid, rifampin, and ethambutol treatment. Telemedicine allowed a cutaneous tuberculosis diagnosis to be made of a patient living in a remote town located in the Amazon jungle by using molecular biology techniques.

The application of recombinant human collagen in tissue engineering.

Collagen is the main structural protein in vertebrates. It plays an essential role in providing a scaffold for cellular support and thereby affecting cell attachment, migration, proliferation, differentiation, and survival. As such, it also plays an important role in numerous approaches to the engineering of human tissues for medical applications related to tissue, bone, and skin repair and reconstruction. Currently, the collagen used in tissue engineering applications is derived from animal tissues, creating concerns related to the quality, purity, and predictability of its performance. It also carries the risk of transmission of infectious agents and precipitating immunological reactions. The recent development of recombinant sources of human collagen provides a reliable, predictable and chemically defined source of purified human collagens that is free of animal components. The triple-helical collagens made by recombinant technology have the same amino acid sequence as human tissue-derived collagen. Furthermore, by achieving the equivalent extent of proline hydroxylation via coexpression of genes encoding prolyl hydroxylase with the collagen genes, one can produce collagens with a similar degree of stability as naturally occurring material. The recombinant production process of collagen involves the generation of single triple-helical molecules that are then used to construct more complex three-dimensional structures. If one loosely defines tissue engineering as the use of a biocompatible scaffold combined with a biologically active agent (be it a gene or gene construct, growth factor or other biologically active agent) to induce tissue regeneration, then the production of recombinant human collagen enables the engineering of human tissue based on a human matrix or scaffold. Recombinant human collagens are an efficient scaffold for bone repair when combined with a recombinant bone morphogenetic protein in a porous, sponge-like format, and when presented as a membrane, sponge or gel can serve as a basis for the engineering of skin, cartilage and periodontal ligament, depending on the specific requirements of the chosen application.

Recombinant collagen and gelatin for drug delivery.

The tools of recombinant protein expression are now being used to provide recombinant sources of both collagen and gelatin. The primary focus of this review is to discuss alternatives to bovine collagen for biomedical applications. Several recombinant systems have been developed for production of human sequence collagens. Mammalian and insect cells were initially used, but were thought to be too costly for commercial production. Yeast have been engineered to express high levels of type I homotrimer and heterotrimer and type II and type III collagen. Co-expression of collagen genes and cDNAs encoding the subunits of prolyl hydroxylase has lead to the synthesis of completely hydroxylated, thermostable collagens. Human types I and III collagen homotrimers have been expressed in transgenic tobacco plants, while transgenic mice have been engineered to produce full-length type I procollagen homotrimer as well as a alpha2 (I) homotrimeric mini-collagen. Most recently, a transgenic silkworm system was used to produce a fusion protein containing a collagenous sequence. Each of these transgenic systems holds great promise for the cost-effective large-scale production of recombinant human collagens. As seen in other recombinant expression systems, transgenic silkworms, tobacco, and mice lack sufficient endogenous prolyl hydroxylase activity to produce fully hydroxylated collagen. In mice and tobacco, this was overcome by over-expression of prolyl hydroxylase, analogous to what has been done in yeast and insect cell culture. In addition to recombinant alternatives to bovine collagen, other sources such as fish and sponge collagen are discussed briefly. Recombinant gelatin has been expressed in Pichia pastoris and Hansenula polymorpha in both non-hydroxylated and hydroxylated forms. Pichia was shown to be a highly productive system for gelatin production. The recombinant gelatins produced in yeast are of defined molecular weight and physio-chemical properties and represent a new biomaterial not previously available from animal sources. Genetic engineering has made great progress in the areas of recombinant collagen and gelatin expression, and there are now several alternatives to bovine material that offer an enhanced safety profile, greater reproducibility and quality, and the ability of these materials to be tailored to enhance product performance.

Biotransformations of the cardiovascular drugs mexrenone and canrenone.

Microbial transformation studies of the cardiovascular drugs mexrenone (1) and canrenone (2) were conducted. Thirty-nine biotransformations of mexrenone and 84 biotransformations of canrenone were analyzed. Metabolism of the substrate was observed in the majority of these cases. Several monohydroxylated derivatives were detected by HPLC-MS-UV and subsequently identified. Two new mexrenone derivatives, 11alpha- (3) and 12beta-hydroxymexrenone (4), and the known metabolite 6beta-hydroxymexrenone (5) were isolated as major products produced by the Beauveria bassiana ATCC 13144 bioconversion (3) and the Mortierella isabellina bioconversion (4 and 5), respectively. Single-elimination products were also sought; however, only the production of the known metabolite Delta(1,2)-mexrenone (6) by several bacteria was confirmed. One new monohydroxylated derivative of canrenone, 9alpha-hydroxycanrenone (7), was isolated as a major product from the Corynespora cassiicola bioconversion. Structure elucidation of all metabolites was based on NMR and HRMS analyses.

Readmission in unstable angina

To determine the characteristics of patients re-admitted after unstable angina (UA) pectoris, 120 consecutive patients hospitalized due to primary UA pectoris were prospectively studied 22 +/- 3 months after discharge. The patients were grouped based on the readmission rate. Those in group A (50) had recurrent admissions (mean 2.6, range 2 to 5). Seventy patients (group B) did not have readmissions during the follow-up period. All patients underwent coronary angiogram and symptoms-limited exercise stress test before discharge. The univariate characteristics for readmission were: age over 70 years (p = 0.02), nondiagnostic exercise stress testing (p = 0.03), angiographically diffuse coronary artery disease (p = 0.004), and non-interventional management (P < 0.001). Patients readmitted had increased incidence of myocardial infarction (p = 0.004) but similar survival at 2 years. By regression analysis, important variables for readmission were non-interventional management (Chi-Square = 7.6, p = 0.01), non diagnostic treadmill test (Chi-Square = 6.9, p = 0.03) and diffuse coronary artery disease (Chi-Square = 6.2, p = 0.04). It is concluded that in the interventional era the most important factor for readmission after primary UA pectoris is non-interventional management. Coronary revascularization should not be denied solely on the basis of age