A strategy to design efficient fermentation processes for traditional beverages production: prickly pear wine.

This paper describes a methodology to establish an optimal process design for prickly pear wine production that preserves the peculiar and unique traits of traditional products, generating at the same time, technical information for appropriate design of both bioreactor and overall process. The strategy includes alcoholic fermentation optimization by the mixed native culture composed by Pichia fermentans and Saccharomyces cerevisiae, followed by malolactic fermentation optimization by Oenococcus oeni. The optimization criteria were based on multiple output functions: alcohol content, volatile compounds profile, organic acids profile, and compound contents related to color, which were analyzed by spectroscopy-chromatography methods and sensory analysis. The results showed that the mixed culture inoculated into a bioreactor containing prickly pear juice with 20 °Bx of fermentable sugars concentration, processed at a constant temperature of 20 °C for 240 h, leads to a fermented product with 9.93% (v/v) total alcohol content, and significant abundance of volatile compounds, which provide fruity and ethereal aromatic notes, complemented by a lively but not unpleasant acidity. This young wine was further subjected to malolactic fermentation at constant temperature (16 °C) for 192 h, decreasing malic acid, and balancing volatile compounds contents, thus resulting in a product with better aroma and flavor perception, and a velvety feeling of long aftertaste. Repeated assays showed that the process is stable, predictable, controllable, and reproducible. These results were used for process design and spreadsheet construction in order to simulate the process, and properly select and size the equipment required for such process.

Kinetic study of the thermal hydrolysis of Agave salmiana for mezcal production.

The kinetics of the thermal hydrolysis of the fructans of Agave salmiana were determined during the cooking step of mezcal production in a pilot autoclave. Thermal hydrolysis was achieved at different temperatures and cooking times, ranging from 96 to 116 °C and from 20 to 80 h. A simple kinetic model of the depolymerization of fructans to monomers and other reducing sugars and of the degradation of reducing sugars to furans [principally 5-(hydroxymethyl)furfural, HMF] was developed. From this model, the rate constants of the reactions were calculated, as well as the pre-exponential factors and activation energies of the Arrhenius equation. The model was found to fit the experimental data well. The tradeoff between a maximum fructan hydrolysis and a critical furan concentration in allowing for the best ethanol yield during fermentation was investigated. The results indicated that the thermal hydrolysis of agave was optimal, from the point of view of ethanol yield in the ensuing fermentation, in the temperature range of 106-116 °C and the cooking range time of 6-14 h. The optimal conditions corresponded to a fructan hydrolysis of 80%, producing syrups with furan and reducing sugar concentrations of 1 ± 0.1 and 110 ± 10 g/L, respectively.

La ecografía carotídea es útil para predecir enfermedad coronaria y mortalidad en pacientes en hemodiálisis / Prognostic value of carotid intima media thickness and wall plaques in hemodialysis patients

Introducción: La enfermedad cardiovascular es la principal causa de muerte en los pacientes urémicos en hemodiálisis (HD). La ecografía carotídea es una herramienta sencilla y no invasiva para conocer el estado aterosclerótico de los pacientes. Objetivo: Conocer las asociaciones clínicas del grosor íntima-media carotídeo (GIM) y de la placa carotí- dea y su valor predictivo sobre el riesgo de enfermedad co- ronaria y la mortalidad. Metodología: Estudio prospectivo en el que se incluyeron 60 pacientes estables en HD (68 ± 13 años, 48% hombres, 50% diabéticos, tiempo en HD de 32 ± 11 meses) y 274 controles, semejantes en edad y sexo. El período de seguimiento fue de 66 ± 13 meses. Determi- naciones: Datos demográficos y clínicos, analítica general y niveles séricos de homocisteína y folato. Se midió el GIM mediante ecocardiografía 2D. Resultados: El GIM fue mayor en los pacientes en HD que en el grupo control (0,947 ± 0,308 frente a 0,619 ± 0,176 mm; p <0,001). El GIM se correlacionó con la edad (r = 0,268; p = 0,038), con la condición de diabético (r = 0,650; p <0,001) y la de hiper- tenso (r = 0,333; p = 0,012), pero no con colesterol total, HDL, LDL, triglicéridos, homocisteína o folato. Los pacien- tes con enfermedad coronaria, enfermedad vascular peri- férica o ictus tenían un GIM mayor que los que no presen- taban dichas afecciones (1,156 ± 0,371 frente a 0,875 ± 0,285 mm; p <0,001; 1,205 ± 0,374 frente a 0,911 ± 0,231 mm; p = 0,007; 1,195 ± 0,264 frente a 0,844 ± 0,251; p <0,001, respectivamente). Se encontraron datos similares respecto a la presencia de placas en la pared carotídea. Durante el período de seguimiento fallecieron 36 pacientes, 24 de los cuales (67%) por causa cardiovascular, cuyo GIM fue mayor (1,020 ± 0,264 frente a 0,858 ± 0,334 mm; p = 0,044). La supervivencia a la finalización del período de es- tudio fue significativamente mejor en el cuartil inferior de GIM (72%) que en el superior (20%). La presencia de pla- cas carotídeas fue predictor independiente de mortalidad cardiovascular. Conclusiones: El GIM y las presencia de pla- cas carotídeas se relacionan con algunos de los factores clá- sicos de riesgo cardiovascular como la edad, la diabetes o la hipertensión en pacientes urémicos. Su medición es útil para predecir la enfermedad coronaria y la mortalidad a largo plazo en los paciente urémicos (AU)

ntroduction: Cardiovascular disease and other complica- tions of atherosclerosis are the most common cause of death in patients with chronic renal failure in maintenance hemodialysis (MHD). Carotid ultrasonography is a simple no invasive tool to investigate the vascular system, by means of intima media thickness (IMT) measurement and carotid wall calcifications. Objective: To determine IMT and the presence of plaques, and their possible clinical re- lationships; finally we tried to investigate whether they would predict cardiovascular morbidity and mortality in patients in MHD. Methods: We studied 60 MHD patients (age 68 ± 13 years, 48% male, 50% diabetics, tiem on MHD 32 ± 11 months) and a control group of 274 people matched for age and sex. Follow-up period was 66 ± 13 months. Measurements: Demographic and clinical data, serum levels of homocysteine (tHcy), folic acid (FA) and B 6 and B 12 vitamins. IMT was measured by high-resolution B- mode ultrasonography. Results: IMT was higher in MHD patients than in those in the control group (0.947 ± 0.308 vs 0.619 ± 0.176 mm; P <0.001). IMT was related with age (r = 0.268; P = 0.038), diabetic (r = 0.650; P <0.001) and hy- pertensive condition (r = 0.333; P = 0.012), but not wih lipids, tHcy or FA. Similar findings were found with the presence or not of carotid plaques but serum LDL-choles- terol levels were also related (r= –0.280; P = 0.031). Patients who suffered from coronary artery disease, peripheral ar- tery disease or stroke had higher IMT than those without those events (1.156 ± 0.371 vs 0.875 ± 0.285 mm; P <0.001; 1.205 ± 0.374 vs 0.911 ± 0.231 mm; P = 0.007; 1.195 ± 0.264 vs 0.844 ± 0.251; P <0.001 respectively). Something similar ocurred with the presence of plaques. During the follow- up period 36 patients (60%) died, 67% of them due to car- diovascular causes. IMT was higher in patients who expired than those who survived (1.020 ± 0.264 vs 0.858 ± 0.334 mm; P = 0.044). The survival rate during the observation was significantly lower in the final IMT fourth (20%) than in the first (72%) (P = 0.014). The presence of carotid plaques was an independent predictor of cardiovascular mortality. Conclusions: These findings suggests that meas- urement of carotid IMT and the presence of wall plaques are useful tools to predict cardiovascular events and mor- tality in patients in MHD (AU)

[Carotid ultrasound: prevention of heart disease and mortality on haemodialysis]. / La ecografía carotídea es útil para predecir enfermedad coronaria y mortalidad en pacientes en hemodiálisis.

INTRODUCTION: Cardiovascular disease and other complications of atherosclerosis are the most common cause of death in patients with chronic renal failure in maintenance hemodialysis (MHD). Carotid ultrasonography is a simple non-invasive tool to investigate the vascular system, by means of intima media thickness (IMT) measurement and carotid wall calcifications. OBJECTIVE: To determine IMT and the presence of plaques, and their possible clinical relationships; finally we tried to investigate whether they would predict cardiovascular morbidity and mortality in patients in MHD. METHODS: We studied 60 MHD patients (age 68 +/- 13 years, 48% male, 50% diabetics, time on MHD 32 +/- 11 months) and a control group of 274 people matched for age and sex. Follow-up period was 66 +/- 13 months. MEASUREMENTS: Demographic and clinical data, serum levels of homocysteine (tHcy), folic acid (FA) and B6 and B12 vitamins. IMT was measured by high-resolution B-mode ultrasonography. RESULTS: IMT was higher in MHD patients than in those in the control group (0.947 +/- 0.308 vs 0.619 +/- 0.176 mm; P < 0.001). IMT was related with age (r = 0.268; P = 0.038), diabetic (r = 0.650; P < 0.001) and hypertensive condition (r = 0.333; P = 0.012), but not wih lipids, tHcy or FA. Patients who suffered from coronary artery disease, peripheral artery disease or stroke had higher IMT than those without those events (1.156 +/- 0.371 vs 0.875 +/- 0.285 mm; P < 0.001; 1.205 +/- 0.374 vs 0.911 +/- 0.231 mm; P = 0.007; 1.195 +/- 0.264 vs 0.844 +/- 0.251; P < 0.001 respectively). Something similar occurred with the presence of plaques. During the follow-up period 36 patients died (60%), 67% of them due to cardiovascular causes. IMT was higher in patients who died than those who survived (1.020 +/- 0.264 vs 0.858 +/- 0.334 mm; P = 0.044). The survival rate during the observation period was significantly lower in the final IMT fourth (20%) than in the first (72%) (P = 0.014). The presence of carotid plaques was an independent predictor of cardiovascular mortality. CONCLUSIONS: These findings suggests that measurement of carotid IMT and the presence of wall plaques are useful tools to predict cardiovascular events and mortality in patients in MHD.

La hipótesis de la abuela / The hypothesis of the grandmother

Una característica que distingue al ser humano del resto de los animales es una larga vida posmenopáusica. Según la hipótesis de la abuela, la menopausia es una adaptación evolutiva. Es el resultado de la hipótesis del cese precoz de la reproducción para permitir una larga vida postreproductiva en la mujer. Esto ha tenido importantes implicaciones en nuestro pasado evolutivo en relación con la organización social, el largo periodo de aprendizaje de las crías humanas, y la dependencia de los padres y parientes para la alimentación y la protección de los niños pequeños

Long postmenopausal lifespans distinguish human from all other mammals. In the grandmother hypothesis, menopause is an evolutionary adaptation. It is about the stopping early reproduction hypothesis in order to create a post reproductive lifespan. Is has implications for past human social organization and it was important for extended learning and paternal provisioning and care of the children in human evolution

[Efficacy and safety of two vitamin supplement regimens on homocysteine levels in hemodialysis patients. Prospective, randomized clinical trial]. / Eficacia y seguridad de dos pautas de suplementos vitamínicos sobre los niveles de homocisteína en pacientes en hemodiálisis. Ensayo clínico prospectivo y randomizado.

UNLABELLED: High levels of homocysteine (tHcy) are frecuent in MHD patients, and recognized as a risk factor for cardiovascular events. Vitamin supplements have been shown to lower serum Hcys, although optimal dose and efficacy is not well defined. Moreover, methylenetetrahydrofolate reductase (MTHFR) gene polymorphism can modulate its prevalence and response to treatment. OBJECTIVE: To evaluate efficacy and safety of two vitamin supplement regimens on Hcys serum levels over a 12 month period. METHODS: We conducted a prospective, randomised, double-blind trial in 60 stable MHD patients (68 +/- 13 years, 48% male, 50% diabetics). Patients were randomly assigned to one of two treatment regimens: 1) daily renal multivitamin containing folate (FA), vitamin B6 and B12 (5 mg, 10 mg and 0.4 mg respectively) (N = 27); and 2) supraphysiological daily doses (15 mg, 100 mg and 1 mg) (N = 33). These regimens were continued throughout the study period. Hcys levels were compared with a control group from the general population (N = 276) matched for age and gender. MEASUREMENTS: demographic and clinical data, serum levels of Hcys, FA, B6, B12 at baseline and after 1, 3, 6 and 12 months of treatment; MTHFR gene polymorphism (PCRRT). RESULTS: At baseline, global prevalence of hyperhomocysteinemia (tHcy > or = 15 micromol/L) was 100% in patients and 22% en controls. Hcys levels were significantly higher in patients versus controls (32.4 +/- 8.9 vs 12.9 +/- 6.8; P < 0.0001). Both regimens were equally effective in reducing Hcys levels. As a whole, Hcys levels were reduced by 23.6% (P < 0.001) after one month of treatment. The highest reduction was observed at the sixth month (28.3%, 32.4 +/- 8.9 vs 22.7 +/- 6.4, P < 0.001) and remained stable thereafter. However, only 12% of patients normalised their plasma levels after 12 months of therapy. The effect of treatment was not influenced by age, gender, diabetes, body weight or time on MHD. Reduction rate of tHcy levels was related to baseline tHcy level (r = 0.500, P < 0.001) and baseline FA levels (r = -0.332, P = 0.009). The MTHFR polimorfism did not significantly modified the effect of the treatment. No side effects were associated with either regimen. CONCLUSIONS: Hyperhomocysteinemia is common in patients with conventional HD schedules and this is not related to vitamin deficiencies. Vitamin supplements significantly reduce Hcys levels in a sustained but suboptimal way. Supraphysiological doses did not improve the results. Further studies are requiered to demonstrate that this effect is associated with an improval in morbidity and mortality.

Eficacia y seguridad de dos pautas de suplementos vitamínicos sobre los niveles de homocisteína en pacientes en hemodiálisis. Ensayo clínico prospectivo y randomizado / Efficacy and safety of two vitamin supplement regimens on hyperhomocysteinemia in maintenance hemodialysis (MHD) patients

La hiperhomocisteinemia (HHcys) es frecuente en pacientes urémicos y representaun factor de riesgo cardiovascular. Los suplementos vitamínicos reducen losniveles de homocisteína (Hcys), no estando bien definida la dosis óptima y su eficacia.El genotipo de la metilentetrahidrofolatoreductasa (MTHFR) puede modularsu prevalencia y respuesta al tratamiento.Objetivo: Conocer la eficacia de dos pautas de suplementos vitamínicos sobrelos niveles de Hcys tras 12 meses de tratamiento.Metodología: Estudio prospectivo, randomizado, a doble ciego. Sesenta pacientesen hemodiálisis se aleatorizaron en dos grupos terapéuticos: A) Dosis habituales deácido fólico (AcF), vitamina B6 y B12 a la dosis de 5, 10 y 0,4 mg diarios, respectivamente(N = 27) y B) Dosis suprafisiológicas (15, 100 y 1 mg diarios) (N = 33).Los valores de Hcys se compararon con un grupo control similar en edad y sexo.Resultados: Todos los pacientes y el 22% de los controles presentaron HHcyssiendo los niveles de Hcys 2,5 veces superiores en los pacientes que en el grupocontrol (32,4 ± 8,9 vs 12,9 ± 6,8 µmol/L; P < 0,0001). Las dos pautas fueron igualmenteeficaces en reducir la Hcys, aunque solamente el 12% de los pacientes normalizaronsus niveles al finalizar el estudio. Globalmente, los niveles de Hcys experimentaronun descenso significativo al mes de tratamiento (23,6%, P < 0,001).El mayor descenso se registró tras 6 meses (28,3%, P < 0,001), estabilizándose hastalos 12 meses. El mayor descenso de Hcys se asoció con niveles basales más altosde Hcys (r = 0,500, P < 0,001) y más bajos de AcF (r = -0,332, P = 0,009). El polimorfismode la MTHFR no modificó significativamente la respuesta terapéutica.Conclusiones: La HHcys es constante con pautas convencionales de hemodiálisisaunque no existan déficits vitamínicos. Los suplementos reducen de forma substancialy sostenida los niveles de Hcys. Dosis suprafisiológicas no suponen ventajasadicionales. Se requieren nuevos estudios para demostrar que este descensoconlleve un impacto final favorable sobre la morbi-mortalidad cardiovascular

High levels of homocysteine (tHcy) are frecuent in MHD patients, and recognizedas a risk factor for cardiovascular events. Vitamin supplements have beenshown to lower serum Hcys, although optimal dose and efficacy is not well defined.Moreover, methylenetetrahydrofolate reductase (MTHFR) gene polymorphismcan modulate its prevalence and response to treatment.Objective: To evaluate efficacy and safety of two vitamin supplement regimenson Hcys serum levels over a 12 month period.Methods: We conducted a prospective, randomised, double-blind trial in 60 stableMHD patients (68 ± 13 years, 48% male, 50% diabetics). Patients were randomlyassigned to one of two treatment regimens: 1) daily renal multivitamin containingfolate (FA), vitamin B6 and B12 (5 mg, 10 mg and 0.4 mg respectively) (N= 27); and 2) supraphysiological daily doses (15 mg, 100 mg and 1 mg) (N = 33).These regimens were continued throughout the study period. Hcys levels werecompared with a control group from the general population (N = 276) matchedfor age and gender. Measurements: demographic and clinical data, serum levelsof Hcys, FA, B6, B12 at baseline and after 1, 3, 6 and 12 months of treatment;MTHFR gene polymorphism (PCRRT).Results: At baseline, global prevalence of hyperhomocysteinemia (tHcy �� 15µmol/L) was 100% in patients and 22% en controls. Hcys levels were significantlyhigher in patients versus controls (32.4 ± 8.9 vs 12.9 ± 6.8; P < 0,0001). Bothregimens were equally effective in reducing Hcys levels. As a whole, Hcys levelswere reduced by 23.6% (P < 0.001) after one month of treatment. The highest reductionwas observed at the sixth month (28.3%, 32.4 ± 8.9 vs 22.7 ± 6.4, P <0.001) and remained stable thereafter. However, only 12% of patients normalisedtheir plasma levels after 12 months of therapy. The effect of treatment was not influencedby age, gender, diabetes, body weight or time on MHD. Reduction rateof tHcy levels was related to baseline tHcy level (r = 0.500, P < 0.001) and baselineFA levels (r = -0.332, P = 0.009). The MTHFR polimorfism did not significantlymodified the effect of the treatment. No side effects were associated witheither regimen.Conclusions: Hyperhomocysteinemia is common in patients with conventionalHD schedules and this is not related to vitamin deficiencies. Vitamin supplementssignificantly reduce Hcys levels in a sustained but suboptimal way. Supraphysiologicaldoses did not improve the results. Further studies are requiered to demonstratethat this effect is associated with an improval in morbidity and mortality

Antropometría y dieta en adolescentes de Badajoz / Anthropometrics and diet of adolescents in Badajoz (Spain)

Antecedentes: La obesidad no es un problema exclusivo de los adultos de los países desarrollados. Los objetivos de este estudio fueron analizar el estado antropométrico y el patrón alimentario e ingesta calórica diaria de adolescentes y jóvenes extremeños. Métodos: Compusieron la población objeto de estudio alumnos de secundaria, bachillerato y primer curso de facultad. Las medidas antropométricas realizadas fueron: peso, talla (índice de masa corporal [IMC]), pliegues cutáneos (porcentaje de peso graso [ por cientoPE]) y perímetros de cintura y cadera (índice cintura cadera [ICC]). Los datos se recogieron mediante encuesta retrospectiva de recuerdo de 24 h con presencia del encuestador. Resultados: Componen la muestra 246 personas, con un 54 por ciento de varones y un 45 por ciento de mujeres. La edad media es de 16,98 ñ 2,39 años. El IMC resultante fue de 22,37 ñ 3,5; con sobrepeso (IMC >= 25) se hallaron el 14 por ciento de los individuos y con obesidad (IMC > 30) el 3 por ciento; el IMC es significativamente superior en los mayores de 18 años (p < 0,05). El consumo calórico medio es de 2.244 ñ 761 kcal/día, superior (p < 0,01) en varones que en mujeres, en todas las comidas. Los hidratos de carbono proporcionan el 40,86 por ciento de las calorías, las proteínas el 17,55 por ciento y los lípidos el 41,58 por ciento. Conclusiones: a) Los sujetos con sobrepeso y obesidad representan el 17 por ciento de la muestra estudiada; b) los varones tienen una ingesta calórica superior que las mujeres en todas las comidas del día, siendo el total de 2.244 ñ 761 kcal; c) el 18 por ciento de las calorías ingeridas al día proceden del consumo entre horas, y d) el consumo de grasas y proteínas es más alto que el recomendado; el de glúcidos, menor (AU)

[Vascular risk factors in non-insulin-dependent diabetes mellitus. Correlation between albuminuria and glycosylated hemoglobin]. / Factores de riesgo vascular en la diabetes mellitus no insulinodependiente. Correlación entre albuminuria y hemoglobina glicada.

OBJECTIVE: This study compared 23 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 28 non-diabetic control subjects, seeking for associations between NIDDM and other cardiovascular risk factors. The relationship of the glycemic control with the risk factor profile was also assessed. RESULTS: The most outstanding results were: The diabetic group showed higher values in the proportion of subjects with diabetes family history (P < 0.01) and the levels of systolic blood pressure (P < 0.05), total cholesterol (P < 0.05), triglyceridemia (P < 0.001), and total cholesterol to HDL cholesterol ratio (P < 0.01). Within the diabetic group, a positive correlation (r = 0.68, P < 0.001) was found between the percent of glycosylated haemoglobin (HbA1c) and the 24-hour urinary albumin excretion rate (UAER). CONCLUSION: We conclude that NIDDM associates to other cardiovascular risk factors. The correlation of HbA1c with UAER suggests a possible relationship between poor diabetic control and some of the secondary diabetic complications.

Influence of diet and physical exercise on plasma lipid concentrations in an homogeneous sample of young Spanish Air Force pilots.

This study evaluates the influence of diet and physical exercise on plasma lipid concentrations--total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), and the TC:HDL-C ratio, in a homogeneous (age, sex and anxiety levels) group of young pilots divided into the following groups: A. uncontrolled diet and exercise programme; B. controlled diet and uncontrolled exercise programme; C. controlled diet and exercise programme (n = 90). The dietary intake was a typical Mediterranean diet, which was supervised by the Flight Surgeon. The exercise was based on a physical training programme for pilots, directed by the Physical Training Officer. The State-Trait Anxiety Inventory test was performed to evaluate the anxiety levels. This test was supervised by a psychologist. The results showed a marked difference in all the lipid parameters studied between groups with an ad libitum diet versus groups with a controlled diet, this difference being demonstrated by TC and TG concentrations lower in the group with a controlled diet, than in the group with an ad libitum diet. A difference in HDL-C concentrations and TC:HDL-C ratio was found between groups with regular physical training (high HDL-C concentration and low TC:HDL-C ratio) versus groups with unlimited exercise (low HDL-C concentrations and high TC:HDL-C ratio). No differences in the state and trait of anxiety were found among any of the groups. Nevertheless, all the pilots showed a considerable increase in their anxiety state over their own anxiety trait.

Sighs and their relationship to apnea in the newborn infant.

To test the hypothesis that sighs are mechanistically important in triggering apnea, we studied 10 preterm infants, group 1: body weight 1.8 +/- 0.1 kg, gestational age 33 +/- 1 weeks, postnatal age 21 +/- 4 days, and 10 term infants, group 2: body weight 3.9 +/- 0.15 kg, gestational age 40 +/- 0.4 weeks, postnatal age 1.4 +/- 0.2 days. Instantaneous ventilatory changes associated with a sigh were studied in another 10 preterm infants, group 3: body weight 1.6 +/- 0.11 kg, gestational age 32 +/- 0.4 weeks, postnatal age 25 +/- 4 days. Ventilation was measured using a nosepiece and a flow-through system. Sleep states were recorded. Sighs were more frequent in preterm than in term infants (0.4 +/- 0.04 vs. 0.18 +/- 0.03 sighs/min; p = 0.03) and in rapid eye movement than in quiet sleep (0.5 +/- 0.05 vs. 0.3 +/- 0.05 sighs/min; p = 0.05). Of 722 apneas, 235 (33%) were associated with a sigh; of these, 113 (48%) preceded and 122 (52%) followed a sigh. Sighs induced with airway occlusion (groups 1 and 2) were more frequent after occlusion on 21 than on 35% O2, particularly when O2 saturation was low and negative airway pressure high. Instantaneous ventilation measured over 10 breaths preceding a sigh did not show any trend indicating the possible appearance of a sigh. Tidal volume increased from 7.5 +/- 0.7 before the sigh to 18.9 +/- 0.7 ml/kg (p < 0.01) during a sigh, with a significant increase in inspiratory drive. Ventilation increased from 0.327 +/- 0.041 to 0.660 +/- 0.073 l/min/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of 10% O2 on the continuous breathing induced by O2 or O2 plus cord occlusion in the fetal sheep.

Although the administration of 100% O2 alone or combined with umbilical cord occlusion induces continuous breathing and arousal in the fetal sheep (Baier, Hasan, Cates, Hooper, Nowaczyk & Rigatto, 1990a), the individual contribution of O2 and cord occlusion to the response have not been determined. We hypothesized that if O2 is an important factor in the induction of continuous breathing, administration of O2 low enough (10%) to bring fetal arterial PO2 to about 20 torr while the fetus is breathing continuously should reverse these changes. Thus we subjected 12 chronically instrumented fetal sheep to 10% O2 for 10 minutes after the establishment of continuous breathing by O2 (4 fetuses; 137 +/- 1 days) or by O2 plus umbilical cord occlusion (8 fetuses; 134 +/- 1 days). Arterial PO2 decreased from about 250 torr to 20 torr during 10% O2. This induced a significant decrease in breathing output (EMGdi x f) related primarily to a decrease in frequency (f). In 3/5 experiments in 4 fetuses, with O2 alone, apnoea developed within 4 +/- 0.6 min; in 12/13 experiments in 8 fetuses, with added cord occlusion it developed at 5 +/- 0.6 min. With the decrease in PaO2, electrocortical activity (ECoG) switched from low to high-voltage within 6 minutes in 5/5 experiments (O2 alone) and in 11/13 (O2 plus cord occlusion). The findings suggest that umbilical cord occlusion alone is not sufficient to maintain breathing continuously and an increased PaO2 is needed. We speculate that in the fetus there is a vital link between PaO2, breathing and ECoG with low PaO2 inhibiting and high PaO2 favouring breathing and arousal.

A case of hemidiaphragmatic paralysis after an anti-G suit failure.

This paper reports a case of left hemidiaphragmatic paralysis in an instructor pilot and his later recuperation. This incident was provoked by a failure in the anti-G suit, which remained inflated after the aircraft completed the maneuver that had originated the inflation. The spontaneous recuperation of both the respiratory functional test and the neurophysiological pattern are consistent with a Type II Seddon's axonotmesis of the phrenic nerve. Considering the short time of regeneration (6 months), this lesion must have involved the distal portion of the phrenic nerve.

Relation between flight hours and peripheral nervous conduction velocity.

The peripheral nervous system is highly sensitive to variations in the internal medium. A neurophysiological study (peripheral nervous conduction velocity) and an enzymatic study (catalase and glutathione-peroxidase) were performed in both instructor and student pilots. Pilots do not show the age-dependent decrease in the peripheral sensory nervous conduction velocity observed in non-pilot subject controls. The sensory conduction velocity (SCV) was significantly (p less than 0.01) increased when hours of flight experience increased, yielding a positive correlation (r = 0.6461; p = 0.0016). A significant (p less than 0.01) increase in the erythrocite catalase and glutathione-peroxidase activities were observed in pilots vs. controls. The present data suggest that a chronically increased oxygen consumption could be the reason for the increase in peripheral nervous conduction velocity observed in pilots.