Geometric and dosimetric evaluations of atlas-based segmentation methods of MR images in the head and neck region.

Owing to its excellent soft-tissue contrast, magnetic resonance (MR) imaging has found an increased application in radiation therapy (RT). By harnessing these properties for treatment planning, automated segmentation methods can alleviate the manual workload burden to the clinical workflow. We investigated atlas-based segmentation methods of organs at risk (OARs) in the head and neck (H&N) region using one approach that selected the most similar atlas from a library of segmented images and two multi-atlas approaches. The latter were based on weighted majority voting and an iterative atlas-fusion approach called STEPS. We built the atlas library from pre-treatment T1-weighted MR images of 12 patients with manual contours of the parotids, spinal cord and mandible, delineated by a clinician. Following a leave-one-out cross-validation strategy, we measured the geometric accuracy by calculating Dice similarity coefficients (DSC), standard and 95% Hausdorff distances (HD and HD95), and the mean surface distance (MSD), whereby the manual contours served as the gold standard. To benchmark the algorithm, we determined the inter-observer variability (IOV) between three observers. To investigate the dosimetric effect of segmentation inaccuracies, we implemented an auto-planning strategy within the treatment planning system Monaco (Elekta AB, Stockholm, Sweden). For each set of auto-segmented OARs, we generated a plan for a 9-beam step and shoot intensity modulated RT treatment, designed according to our institution's clinical H&N protocol. Superimposing the dose distributions on the gold standard OARs, we calculated dose differences to OARs caused by delineation differences between auto-segmented and gold standard OARs. We investigated the correlations between geometric and dosimetric differences. The mean DSC was larger than 0.8 and the mean MSD smaller than 2 mm for the multi-atlas approaches, resulting in a geometric accuracy comparable to previously published results and within the range of the IOV. While dosimetric differences could be as large as 23% of the clinical goal, treatment plans fulfilled all imposed clinical goals for the gold standard OARs. Correlations between geometric and dosimetric measures were low with R2 < 0.5. The geometric accuracy and the ability to achieve clinically acceptable treatment plans indicate the suitability of using atlas-based contours for RT treatment planning purposes. The low correlations between geometric and dosimetric measures suggest that geometric measures alone are not sufficient to predict the dosimetric impact of segmentation inaccuracies on treatment planning for the data utilised in this study.

Evaluation of a multi-atlas CT synthesis approach for MRI-only radiotherapy treatment planning.

BACKGROUND AND PURPOSE: Computed tomography (CT) imaging is the current gold standard for radiotherapy treatment planning (RTP). The establishment of a magnetic resonance imaging (MRI) only RTP workflow requires the generation of a synthetic CT (sCT) for dose calculation. This study evaluates the feasibility of using a multi-atlas sCT synthesis approach (sCTa) for head and neck and prostate patients. MATERIAL AND METHODS: The multi-atlas method was based on pairs of non-rigidly aligned MR and CT images. The sCTa was obtained by registering the MRI atlases to the patient's MRI and by fusing the mapped atlases according to morphological similarity to the patient. For comparison, a bulk density assignment approach (sCTbda) was also evaluated. The sCTbda was obtained by assigning density values to MRI tissue classes (air, bone and soft-tissue). After evaluating the synthesis accuracy of the sCTs (mean absolute error), sCT-based delineations were geometrically compared to the CT-based delineations. Clinical plans were re-calculated on both sCTs and a dose-volume histogram and a gamma analysis was performed using the CT dose as ground truth. RESULTS: Results showed that both sCTs were suitable to perform clinical dose calculations with mean dose differences less than 1% for both the planning target volume and the organs at risk. However, only the sCTa provided an accurate and automatic delineation of bone. CONCLUSIONS: Combining MR delineations with our multi-atlas CT synthesis method could enable MRI-only treatment planning and thus improve the dosimetric and geometric accuracy of the treatment, and reduce the number of imaging procedures.

Mercury in Pelecanus occidentalis of the Cispata bay, Colombia / Mercurio en Pelecanus occidentalis de la bahía de Cispatá, Colombia

Objective. Assessment the total concentration of mercury in the liver and feathers of Pelecanus occidentalis of the Cispata bay, Colombia. Materials and methods. Mercury concentrations in liver and feather of Pelecanus occidentalis residents in the Cispata bay - Colombia were evaluated by digestion with an acidic mixture of H2SO4-HNO3 and KMnO4 to eliminate organic matter. The concentration of mercury was determined by the Atomic Absorption - Cold Vapor method (CVAAS). Results. Total mercury levels found in this study were higher in feathers (0.31-9.17 mgHg/kg) than in the liver (0.63-6.29 mgHg/kg), being higher than those reported in other seabirds studies. Conclusions. The high levels of total mercury in feathers and liver can be explained by the feeding habits of the organisms under study, showing the utility of feathers as a potential non-invasive tool for the monitoring of the ecosystem and thereby preventing the sacrifice of specimens.

Objetivo. Evaluar las concentraciones de mercurio total en hígado y plumas de Pelecanus occidentalis de la Bahía de Cispatá, Colombia. Materiales y métodos. Se evaluó la concentración de mercurio en hígado y plumas de Pelecanus occidentalis pertenecientes a la bahía de Cispatá - Colombia, por digestión con una mezcla ácida de H2SO4-HNO3 y KMnO4 para eliminar la materia orgánica. La concentración de mercurio fue determinada por el método de Absorción Atómica - Vapor Frio (CVAAS). Resultados. Los valores de mercurio total fueron más altos en plumas (0.31-9.17 mgHg/kg) que en hígado (0.63-6.29 mgHg/kg), siendo mayores a los reportados en otros estudios de aves marinas. Conclusiones. Las altas concentraciones de mercurio total en plumas e hígado pueden ser atribuidas a la dieta de los organismos estudiados; demostrando la utilidad de las plumas como herramienta potencial no invasiva de monitoreo del ecosistema y evitando con ello el sacrificio de los individuos.

Segundos cánceres primarios / Second primary cancers

Los Segundos Cánceres Primarios (SCP) pueden ocurrir con frecuencia. Según datos de la SEER (Surveillance, Epidemiology and End Results) pueden constituir hasta un 16 por ciento de la incidencia total de cáncer. Se reporta una serie de casos conformada por 11 pacientes (2 hombres y 9 mujeres) con edad promedio de 61 años. En esta serie se presentaron 3 casos de cánceres sincrónicos y 8 metacrónicos, con un intervalo entre ambos de 2 a 72 meses. Se analizan diversos aspectos del tema como la quimioprevención y los aspectos relacionados con los SCP asociados a terapias (quimioterapia y radioterapia). Se describen aspectos particulares de los pacientes fumadores que constituyen un grupo especial de riesgo, debido al tipo de carcinógeno al que se ven expuestos. Finalmente se revisa el concepto de cancerización de campo que los afecta mayoritariamente.

Tabaco, cirugía y cáncer / Tobacco, surgery and cancer

El tabaquismo constituye un grave problema de salud pública. Pese a los avances en el marco legal, hoy en Chile fuma el 44.8 por ciento de los hombres y el 40.4 por ciento de las mujeres, lo que determina que un número significativo de estos pacientes fumadores llega a someterse a una cirugía electiva o de urgencia sin un período de abstinencia, lo cual trae aparejado un incremento de las complicaciones perioperatorias derivadas del hábito. Por otra parte, está clara la relación entre tabaco y cáncer. Lamentablemente y pese a la evidencia existente, los pacientes con cáncer no reciben asistencia especializada respecto a los efectos negativos que tiene para ellos el continuar fumando una vez diagnosticados. El tabaco afecta el resultado oncológico final a través de variados efectos como son el producir recurrencias más precoces, reducir el efecto de la quimio y radioterapia, aumentar los efectos adversos de las terapias, producir más complicaciones quirúrgicas y aumentar la tasa de segundos cánceres primarios entre otros. En esta revisión se analizan los factores asociados al tabaquismo en pacientes sometidos a cirugía, su rol etiológico en cáncer y cómo afecta negativamente a los pacientes oncológicos que continúan fumando.

Caregivers' perception of HIV-infected Dominican children's behaviour.

Caregivers (mothers and non-mothers) of HIV children face many challenges related to both physical demands and emotional well-being. The perception of caregivers in the Dominican Republic, a country greatly impacted by HIV/AIDS, in regard to their children's behaviour, has not been investigated to date. To extend understanding of the potential behavioural issues involved in providing care to children without access to antiretroviral therapy, the Child Behaviour Checklist was administered to 52 caregivers of HIV Dominican children (2-8 years old). Both mothers and non-mothers perceived significant pathological internalizing behavioural symptoms in immunosuppressed children, compared to children with less disease progression. Analyses of gender comparisons revealed that older female children were perceived as withdrawn/depressed by their caregivers. These findings suggest that children's disease status may be an important contributor to caregiver perception in mothers, as well as non-mothers and indicate that gender-specific relationships warrant further study.

Behavioural symptoms of children with HIV infection living in the Dominican Republic.

OBJECTIVE: The purpose of this report is to describe behavioural problems encountered in a group of Dominican children living with Human Immunodeficency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) in the Dominican Republic. They were not receiving antiretroviral treatment. METHOD: The participants were 43 children with HIV infection (2 to 8 years of age) who were attending an immunology clinic in the largest paediatric hospital in the Dominican Republic. All of the participants were vertically infected with the HIV virus (mother-to-child transmission) and had a very low socio-economic status. The children's caregivers were administered the Child Behavioural Checklist (CBCL) by trained psychologists to determine the caregivers 'perception of the children's behavioural problems. Behavioural findings were examined according to the CBCL age format: younger children (under 5 years of age) and older children (over 6 years of age). RESULTS: Descriptive statistics revealed a high proportion of the children, both younger (approximately 40%) and older (46%) scored in the borderline/clinical ranges for internalizing problems, including anxiety, withdrawn-depressed and somatic complaints. In addition, 46% of the older children were perceived as having externalizing problems (rule breaking and aggressive behaviour). CONCLUSION: These findings suggest that a high incidence of behavioural and mood problems may be prevalent among Dominican children with HIV Thefindings are discussed in terms of future research to examine other risk factors that might contribute to the high rate of maladaptive behaviours observed in the present report, including the contribution of socio-economic status, caregiver illness, caregiver education and parental loss.

Caregivers' perception of HIV-infected Dominican children's behaviour / La percepción de los encargados del cuidado de la salud en relación con la Conducta de niños dominicanos infestados por vih

Caregivers (mothers and non-mothers) of HIV children face many challenges related to both physical demands and emotional well-being. The perception of caregivers in the Dominican Republic, a country greatly impacted by HIV/AIDS, in regard to their children's behaviour, has not been investigated to date. To extend understanding of the potential behavioural issues involved in providing care to children without access to antiretroviral therapy, the Child Behaviour Checklist was administered to 52 caregivers of HIV Dominican children (2-8 years old). Both mothers and non-mothers perceived significant pathological internalizing behavioural symptoms in immunosuppressed children, compared to children with less disease progression. Analyses of gender comparisons revealed that older female children were perceived as withdrawn/depressed by their caregivers. These findings suggest that children's disease status may be an important contributor to caregiver perception in mothers, as well as non-mothers and indicate that gender-specific relationships warrant further study.

Los encargados del cuidado de la salud (madres y no madres) de niños HIV+ enfrentan muchos retos, tanto en relación con las exigencias físicas cuanto con respecto al estado emocional de los niños. La percepción de los encargados del cuidado de la salud en República Dominicana ­ un país muy impactado por el VIH/SIDA ­ con respecto a la conducta de sus niños, no se ha investigado hasta hoy. A fin de extender la comprensión de los problemas potenciales de comportamiento implícitos en ofrecer cuidado a niños sin acceso a terapia antiretroviral, se administró la Lista de Conductas Infantiles ­ conocida en inglés como Chile Behaviour Checklist ­ a los encargados del cuidado de la salud de los niños dominicanos VIH+ (2 ­ 8 años de edad). Tanto las madres como las no madres percibieron síntomas significativos de conducta de interiorización patológica en los niños inmunodeprimidos, en comparación con los niños con la enfermedad menos avanzada. Los análisis de las comparaciones de género revelaron que las niñas de más edad, pero no los varones, eran percibidas como retraídas/ deprimidas por los encargados del cuidado. Estos hallazgos sugieren que el estatus de la enfermedad de los niños, puede ser un factor que contribuye de forma importante a la percepción de los encargados del cuidado de la salud, ya sean o no madres, e indioan que las relaciones específicas de género merece más estudio

Behavioural symptoms of children with HIV infection living in the Dominican Republic / Síntomas de conducta de los niños infectados por vih en la república dominicana

OBJECTIVE: The purpose of this report is to describe behavioural problems encountered in a group of Dominican children living with Human Immunodeficency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) in the Dominican Republic. They were not receiving antiretroviral treatment. METHOD: The participants were 43 children with HIV infection (2 to 8 years of age) who were attending an immunology clinic in the largest paediatric hospital in the Dominican Republic. All of the participants were vertically infected with the HIV virus (mother-to-child transmission) and had a very low socio-economic status. The children's caregivers were administered the Child Behavioural Checklist (CBCL) by trained psychologists to determine the caregivers 'perception of the children's behavioural problems. Behavioural findings were examined according to the CBCL age format: younger children (under 5 years of age) and older children (over 6 years of age). RESULTS: Descriptive statistics revealed a high proportion of the children, both younger (approximately 40) and older (46) scored in the borderline/clinical ranges for internalizing problems, including anxiety, withdrawn-depressed and somatic complaints. In addition, 46of the older children were perceived as having externalizing problems (rule breaking and aggressive behaviour). CONCLUSION: These findings suggest that a high incidence of behavioural and mood problems may be prevalent among Dominican children with HIV Thefindings are discussed in terms of future research to examine other risk factors that might contribute to the high rate of maladaptive behaviours observed in the present report, including the contribution of socio-economic status, caregiver illness, caregiver education and parental loss.

Objetivo. El propósito de este reporte es describir los problemas conductuales hallados en un grupo de niños dominicanos que viven con el virus de la inmunodeficiencia humana/síndrome de la inmunodeficiencia humana adquirida (VIH/AIDS) en República Dominicana, sin recibir tratamiento antiretroviral. Método. Los participantes fueron 43 niños (de 2 a 8 años de edad) infectados por el VIH, que asistían a una clínica inmunológica en el mayor hospital pediátrico de la República Dominicana. Todos los participantes estaban verticalmente infectados por el virus del VIH (transmisión de madre a hijo), y tenían un estatus socioeconómico bajo. Con el propósito de determinar la percepción que los encargados del cuidado de los niños tenían de los problemas conductuales de estos, psicólogos profesionales aplicaron a los cuidadores infantiles el instrumento conocido como la Lista de Control de la Conducta del Niño (CBCL). Los hallazgos conductuales fueron examinados de conformidad con el formato de edad de la CBCL: niños menores (por debajo de los 5 años de edad) y niños mayores (más de 6 años de edad) Resultados. Las estadísticas descriptivas revelaron que una alta proporción de niños, tanto menores (aproximadamente 40%) como mayores (46%), alcanzaron puntuaciones en los rangos clínicos/límites de problemas de internalización, incluyendo ansiedad, depresión con retraimiento, y quejas somáticas. Además, del 46% de los niños mayores se tuvo la percepción de que tenían problemas de externalización (rompimiento de las reglas y comportamiento agresivo). Conclusión. Estos hallazgos sugieren que prevalece una alta incidencia de problemas conductuales y anímicos entre los niños dominicanos con VIH. Los hallazgos se discuten en término de una investigación futura a fin de examinar otros factores de riesgo que podrían estar contribuyendo a la alta tasa de comportamientos maladaptativos observados en el reporte presente, incluyendo la contribución del estatus socioeconómico, la enfermedad de los propios cuidadores, la educación de los cuidadores y la pérdida de los padres.

Growth inhibition and root ultrastructure of cucumber seedlings exposed to allelochemicals from rye (Secale cereale).

Inhibition of "Calypso" cucumber seedling growth by rye allelochemicals, 2(3H)-benzoxazolinone BOA and 2,4-dihydroxy-1,4(2H)-benzoxazin-3-one DIBOA, was studied by analyzing the growth of seedling tissues and organs. Light and electron microscopy of seedling root cells were also carried out to investigate the mechanism(s) of root growth inhibition and mode of action of these compounds. BOA inhibited root elongation and reduced the number of cucumber lateral roots by 77 and 100% at 0.1 and 0.43 mg BOA/ml deionized (DI) water, respectively. DIBOA also inhibited root growth, but did not affect the number of lateral roots. BOA increased size of cucumber cortical root cells fivefold, but DIBOA had no effect. Both compounds reduced the regeneration of root cap cells and increased the width of cortical cells resulting in increased root diameter. BOA and DIBOA caused increased cytoplasmic vacuolation, reduced ribosome density and dictyosomes, reduced number of mitochondria, and reduced lipid catabolism. Starch granules in amyloplasts of seedling roots treated with BOA and DIBOA were also greatly reduced compared to the control. Changes in cellular ultrastructure indicated that BOA and DIBOA reduced root growth by disrupting lipid metabolism, reducing protein synthesis, and reducing transport or secretory capabilities.

Arginine kinase of the flagellate protozoa Trypanosoma cruzi. Regulation of its expression and catalytic activity.

In epimastigotes of Trypanosoma cruzi, the etiological agent of Chagas' disease, arginine kinase activity increased continuously during the exponential phase of growth. A correlation between growth rate, enzyme-specific activity and enzyme protein was observed. Arginine kinase-specific activity, expressed as a function of enzyme protein, remains roughly constant up to 18 days of culture. In the whole range of the culture time mRNA levels showed minor changes indicating that the enzyme activity is post-transcriptionally regulated. Arginine kinase could be proposed as a modulator of energetic reserves under starvation stress condition.

Amaranthus palmeri resistance and differential tolerance of Amaranthus palmeri and Amaranthus hybridus to ALS-inhibitor herbicides.

Suspected imazaquin-resistant accessions of Amaranthus palmeri were studied to determine the magnitude of resistance and cross-resistance to acetolactate synthase (ALS)-inhibiting herbicides and compare differential tolerance of A palmeri and Amaranthus hybridus to ALS inhibitors. Five of seven A palmeri accessions were resistant to imazaquin. The most imazaquin-resistant accession, accession 7, also showed 74, 39 and 117 times higher resistance than the susceptible biotype to chlorimuron, diclosulam and pyrithiobac, respectively. Resistance to imazaquin and cross-resistance to other ALS inhibitors in A palmeri was due to a less-sensitive ALS enzyme. A palmeri was 70 times more tolerant to imazaquin than A hybridus. A palmeri was also seven times more tolerant to pyrithiobac than A hybridus. Differences in ALS enzyme sensitivity could not fully account for the high tolerance of A palmeri to imazaquin compared to A hybridus. Both species were equally affected by chlorimuron and diclosulam.

Comparative study of enzymes in testes and ovaries from adult Dipetalogaster maximus (Uhler) and triatoma infestans (Klug) (Hemiptera: Reduviidae). correlation with fine structural organization.

Activities of hexokinase (HK), glucose-6-phosphate dehydrogenase (G6PDH), fructose-6-phosphate kinase (F6PK), glutamate dehydrogenase (GlutDH), aspartate aminotransferase (AAT), malate dehydrogenase (MDH) and glycerol-3-phosphate dehydrogenase (GPDH) were determined in tissue extracts of testes and ovaries of adult Dipetalogaster maximus (Uhler) and Triatoma infestans (Klug) (Hemiptera: Reduviidae), insect vectors of Chagas disease. The fine structure organization of the same organs were studied by electron microscopy. Results allow the following inferences: in testes from both species, most of the glucose would be utilized through the glycolytic pathway. Amino acid catabolism for energy purposes appears to be unimportant. The number of mitochondria and the development of the rough endoplasmic reticulum in cells of the spermatogenic line indicate the occurrence of active oxidative metabolism and protein synthesis; in ovaries, levels of G6PDH indicate the existence of an active pentose pathway which would supply the NADPH required for fat and ecdysteroid synthesis. Amino acid catabolism appears to be relatively more important in ovary than in testis. Fat and glycogen are stored in follicular cells of D. maximus; oocytes of both species contain numerous fat droplets. Abundant mitocondria are present in follicular cells and oocytes. A well developed rough endoplasmic reticulum and free ribosomes are also conspicuous in these cells. The malate/aspartate H-transfer system seemed to be relatively more important than the glycerophosphate shuttle in ovaries as well in testes.

Presence of a fatty acid-binding protein and lipid stores in flight muscles of Dipetalogaster maximus (Hemiptera: Reduviidae).

A fatty acid-binding protein (FABP) from the cytosolic fraction of the triatomine Dipetalogaster maximus (Uhler) flight muscles was purified by a procedure based on gel filtration, reverse-phase high performance liquid chromatography, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The protein has an apparent molecular mass of 14 kDa, and its N-terminus is unblocked. Its N-terminal sequence was obtained by submitting an SDS-PAGE band blotted onto a polyvinylidene difluoride membrane to Edman degradation. The sequence obtained indicates that this FABP belongs to the heart type. This is the first time that a fatty acid-binding protein has been reported for a triatomine. The presence of said FABP, abundant mitochondria, and lipid stores in the flight muscles of D. maximus suggests that beta oxidation of fatty acids is used by the triatomine thoracic muscle as an energy source, and could be related to its dispersal capacity.

Subverting culture: promoting HIV/AIDS prevention among Puerto Rican and Dominican women.

This article discusses the challenges faced by researchers and interventionists when attempting to promote change in social norms and normative beliefs that promote HIV/AIDS risk-related behaviors among Puerto Rican and Dominican women. The article focuses on the role of culture in HIV/AIDS prevention with women by analyzing the sociohistorical context of some cultural beliefs and by illustrating the tension between risk-related and protective cultural beliefs in research conducted by the authors with women in both New York and Puerto Rico. The authors propose that promoting changes in sex-related social norms and normative beliefs might be constructed as a subversive act and present the challenge this analysis poses for community psychology. They conclude that this conceptualization might be construed as subversive because rather than idealizing culture, it promotes changes that respect diversity within the culture and foster participation in the development of new cultural values, beliefs and norms.

Effects of temperature and pH on hexokinase from the flight muscles of Dipetalogaster maximus (Hemiptera: Reduviidae).

Effects of temperature and pH on the catalytic properties of hexokinase (HK, EC 2.7.1.1) from the flight muscles of Dipetalogaster maximus (Uhler) were studied. The enzyme showed a hyperbolic behavior with its two substrates (glucose and ATP). There was no inhibition by glucose. Apparent Km and Vmax increased as pH increased from 7.0 to 8.5. Catalytic efficiency was lowest at pH 7.0. Km, Vmax, and catalytic efficiency were higher at 37 degrees C than at 30 and 20 degrees C. There was marked inhibition by ATP, which was dependent on pH and temperature. Km values for ATP were reduced and catalytic efficiency increased as pH increased. Lowest Vmax was observed at pH 7.0. At this pH there was 87.3% inhibition by ATP, whereas it was only 5.7% at pH 8.5 (at 30 degrees C). Km, Vmax, and catalytic efficiency were higher at 37 degrees C than at 30 and 20 degrees C. The strong inhibition by ATP detected at 20 degrees C (pH 7.6) almost disappeared at 37 degrees C. Therefore, temperature could regulate hexokinase activity by modulating the inhibition produced by ATP. Glucose utilization and ATP production would be promoted when temperature rises from 30 to 37 degrees C. Because insect thoracic muscles increase their temperature over 30 degrees C during flight, this phenomenon elucidates a mechanism enhancing energy supply for muscle activity.

[Acute poisoning with methotrexate used as an abortifacient: description of 2 cases]. / Intoxicación aguda con metotrexato usado con fines abortivos: descripción de 2 casos.

Acute intoxication with methotrexate, used as an abortive, has not been described in Chile. We report two female patients, aged 15 and 24 years old, who presented with mucositis, erythrodermia, pancytopenia, and elevation of hepatic enzymes. Plasma methotrexate levels confirmed the clinical diagnosis and both patients were treated with high leucovorin doses and management of associated complications. In one patient, pregnancy continued, giving birth to a newborn with cranial, face and limb malformations. The second patient had a late rescue with leucovorin and was discharged with a persistent sensory motor neuropathy. Considering the severity of complications and that patients may deny its use, when there is reasonable clinical suspicion of methotrexate intoxication, leucovorin treatment should be started.

Influence of Whitacre spinal needle orifice direction on the level of sensory blockade.

The purposes of the present study were to determine if the direction of the needle orifice during injection of anesthetic into the subarachnoid space, using a 25-gauge Whitacre spinal needle (Becton Dickinson, Franklin Lakes, NJ) to deliver 15 mg of 0.75% hyperbaric bupivacaine, affected the level of sensory blockade achieved, and if there was a difference in time from injection to surgical anesthesia based on needle orifice direction. A convenience sample was selected from patients presenting for elective surgical procedures. All patients received a standard anesthetic solution using a standard technique and duration of injection. Mean maximum height of sensory blockade was compared between treatment groups using a Student t test. Progression of the sensory blockade was compared at each data collection point using a chi-square test. There was no statistically significant difference in the mean maximum height of block between the treatment groups. The mean maximum height of block for the cephalad group was T4 with an SD of 2.5 dermatomes, and T5 with an SD of 4.57 dermatomes for the caudad group. An incidental finding was that all failed blocks were from the caudad group. There was no statistically significant difference in time from injection to surgical anesthesia between the treatment groups. Although the data support no statistically significant difference between the treatment groups for either research question, the cephalad group provides for a more precise height of block.

Enzymatic method for branched chain alpha-ketoacid determination: application to rapid analysis of urine and plasma samples from maple syrup urine disease patients.

A new method for the determination of branched-chain alpha-ketoacid concentration using lactate dehydrogenase (E C 1.1.1.27) isozyme C4 (LDH C4) from mouse testes is proposed. The assay is performed on urine and plasma without previous treatment. Alpha-ketoglutarate and pyruvate are determined on the same sample using glutamate dehydrogenase (GDH, EC 1.4.1.2) and lactate dehydrogenase isozyme A4 (LDH5) respectively and subtracted from the total alpha-ketoacid concentration obtained with LDH C4. This value corresponds to the branched chain alpha-ketoacid. Results were linear within the concentration range 8 to 170 mumoles/L. Detection limit was 8 mumoles/L. Analytical recovery was higher than 91%. For microplate assays, recoveries were higher than 84% and the detection limit was 20 mumoles/L. Determinations performed with GDH, LDH A4 and LDH C4 allow differentiation of E3 deficiency from other clinical phenotypes of maple syrup urine disease. The method is simple and fast, and adaptation to microplates would allow screening of newborns.

Intracellular localization of the testicular and sperm-specific lactate dehydrogenase isozyme C4 in mice.

The proposed dual intracellular distribution of the sperm-specific lactate dehydrogenase (EC 1.1.1.27) isozyme C4 (LDH C4) has been based on indirect evidence. In order to obtain direct evidence on the localization of this LDH isozyme in mice, postembedding immunocytochemistry at ultrastructural level was performed on testes, epididymal spermatozoa, and isolated testicular mitochondria. The immunogold technique was applied to thin sections incubated first in partially purified specific anti-LDH C4 rabbit IgG, and immunoreactive sites were detected with colloidal gold adsorbed to anti-rabbit IgG. In the testis, immunostaining was found in the cytoplasm of spermatocytes and spermatids and in the principal and middle pieces of differentiating spermatozoa. Spermatozoa from epididymis also exhibited heavy labeling of colloidal gold in their middle and principal pieces, but the immunostaining was weak in the special type of mitochondria present in spermatocytes, spermatids, and spermatozoa (sperm-type mitochondria, STM). The isolation of STM produced several morphological changes in comparison with those in situ, including an enhancement of the LDH C4 labeling in the mitochondrial matrix. The other type of mitochondria (non-STM) from spermatocytes and nonspermatogenic cells were not immunostained and served as background control. The results presented here confirm previous findings, gathered by indirect methods, indicating a dual localization of LDH C4 in the cytosol of spermatocytes, spermatids, and spermatozoa, as well as in the matrix of sperm-type mitochondria.