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Biomedical subjects

V Diaz

Publications and source records attributed to V Diaz.

At least 19 recordsLinked to original sources
PubMed2002

Estimation of carotenoid accessibility from carrots determined by an in vitro digestion method.

OBJECTIVE: To develop an in vitro digestion method to assess the impact of heat treatment, particle size and presence of oil on the accessibility (available for absorption) of alpha- and beta-carotene in carrots. DESIGN: Raw and cooked carrots were either homogenized or cut into pieces similar to chewed items in size. The carrot samples, with or without added cooking oil, were exposed to an in vitro digestion procedure. Adding a pepsin-HCl solution at pH 2.0 simulated the gastric phase. In the subsequent intestinal phase, pH was adjusted to 7.5 and a pancreatin-bile extract mixture was added. Carotenoids released from the carrot matrix during the digestion were extracted and quantified on high-performance liquid chromatography (HPLC). RESULTS: Three percent of the total beta-carotene content was released from raw carrots in pieces. When homogenized (pulped) 21% was released. Cooking the pulp increased the accessibility to 27%. Addition of cooking oil to the cooked pulp further increased the released amount to 39%. The trends for alpha-carotene were similar to those for beta-carotene. CONCLUSION: The described in vitro digestion method allows a rapid estimation of carotene accessibility in processed carrots, which may reliably predict in vivo behavior. SPONSORSHIP: This study was supported by the Swedish International Development Cooperation Agency (SIDA) and the International Program in the Chemical Sciences (IPICS), Uppsala University, Sweden.

Antioxidants↗
PubMed2001

New insights into host factor requirements for prokaryotic beta-recombinase-mediated reactions in mammalian cells.

The prokaryotic beta-recombinase catalyzes site-specific recombination between two directly oriented minimal six sites in mammalian cells, both on episomic and chromatin-integrated substrates. Using a specific recombination activated gene expression system, we report the site-specific recombination activity of an enhanced green fluorescent protein (EGFP) fused version of beta-recombinase (beta-EGFP). This allows expression of active beta-recombinase detectable in vivo and in fixed cells by fluorescence microscopy. In addition, cellular viability is compatible with a substantial level of expression of the beta-EGFP protein. Using fluorescence-activated cell sorting, we have been able to enrich cell populations expressing this fusion protein. Application of this strategy has allowed us to study in more depth the host factor requirements for this system. Previous work showed that eukaryotic HMG1 protein was necessary and sufficient to help beta-recombinase activity in vitro. The influence of ectopic expression of HMG1 protein in the recombination process has been analyzed, indicating that HMG1 overexpression does not lead to a significant increase on the efficiency of beta-recombinase-mediated recombination both on episomal substrates and chromatin-associated targets. In addition, beta-recombinase-mediated recombination has been demonstrated in HMG1 deficient cells at the same levels as in wild type cells. These data demonstrate the existence of cellular factors different from HMG-1 that can act as helpers for beta-recombinase activity in the eukaryotic environment.

3T3 Cells↗
PubMed2000

Consequences of capsaicin treatment on pulmonary vagal reflexes and chemoreceptor activity in lambs.

The aim of this study was to test the hypothesis that capsaicin treatment in lambs selectively inhibits bronchopulmonary C-fiber function but does not alter other vagal pulmonary receptor functions or peripheral and central chemoreceptor functions. Eleven lambs were randomized to receive a subcutaneous injection of either 25 mg/kg capsaicin (6 lambs) or solvent (5 lambs) under general anesthesia. Capsaicin-treated lambs did not demonstrate the classical ventilatory response consistently observed in response to capsaicin bolus intravenous injection in control lambs. Moreover, the ventilatory responses to stimulation of the rapidly adapting pulmonary stretch receptors (intratracheal water instillation) and slowly adapting pulmonary stretch receptors (Hering-Breuer inflation reflex) were similar in both groups of lambs. Finally, the ventilatory responses to various stimuli and depressants of carotid body activity and to central chemoreceptor stimulation (CO(2) rebreathing) were identical in control and capsaicin-treated lambs. We conclude that 25 mg/kg capsaicin treatment in lambs selectively inhibits bronchopulmonary C-fiber function without significantly affecting the other vagal pulmonary receptor functions or that of peripheral and central chemoreceptors.

Age Factors↗
PubMed1999

Radiotelemetry system for apnea study in lambs.

Neonatal apneas are being studied in the laboratory using polysomnographic recordings in lambs. Standard equipment, requiring animal restraint, disrupts sleep and prevents development of spontaneous apneas. The aim of the current work was to develop and validate a wireless recording equipment to study freely moving lambs. Firstly, a radiotelemetry equipment composed of a multichannel FM transmitter and a receiver was developed. Secondly, to test the telemetry equipment, each biopotential - [electroencephalogram (EEG), electrooculogram (EOG), electrocardiogram (ECG), electromyograms (EMGs), nasal airflow] - was recorded simultaneously by standard equipment and by telemetry (5 lambs). The results indicated an excellent concordance between signals obtained by both systems. Finally, the 8-channel telemetry prototype was tested for polysomnographic recordings (16 lambs). Results obtained confirmed the possibility of recording frequent REM sleep periods and spontaneous apneas. In conclusion, this radiotelemetry polysomnographic equipment brings new possibilities for research on neonatal apneas.

Animals↗
PubMed1999

Vagal afferents and active upper airway closure during pulmonary edema in lambs.

The present study was undertaken to gain further insight into the mechanisms responsible for the sustained active expiratory upper airway closure previously observed during high-permeability pulmonary edema in lambs. The experiments were conducted in nonsedated lambs, in which airflow and thyroarytenoid and inferior pharyngeal constrictor muscle electromyographic activity were recorded. We first studied the consequences of hemodynamic pulmonary edema (induced by impeding pulmonary venous return) on upper airway dynamics in five lambs; under this condition, a sustained expiratory upper airway closure consistently appeared. We then tested whether expiratory upper airway closure was related to vagal afferent activity from bronchopulmonary receptors. Five bivagotomized lambs underwent high-permeability pulmonary edema: no sustained expiratory upper airway closure was observed. Finally, we studied whether a sustained decrease in lung volume induced a sustained expiratory upper airway closure. Five lambs underwent a 250-ml pleural infusion: no sustained expiratory upper airway closure was observed. We conclude that 1) the sustained expiratory upper airway closure observed during pulmonary edema in nonsedated lambs is related to stimulation of vagal afferents by an increase in lung water and 2) a decrease in lung volume does not seem to be the causal factor.

Animals↗
PubMed1999

Effects of capsaicin pretreatment on expiratory laryngeal closure during pulmonary edema in lambs.

The present study, performed in nonsedated, conscious lambs, consisted of two parts. In the first part, we 1) examined for the first time whether a respiratory response to pulmonary C-fiber stimulation could be elicited in nonsedated newborns and 2) determined whether this response could be abolished by capsaicin pretreatment. Then, by using capsaicin-desensitized lambs, we studied whether pulmonary C fibers were involved in the sustained, active expiratory upper airway closure previously observed during pulmonary edema. Airflow and thyroarytenoid and inferior pharyngeal constrictor muscle electromyographic activities were recorded. In the first set of experiments, a 5-10 microg/kg capsaicin bolus intravenous injection in seven intact lambs consistently led to a typical pulmonary chemoreflex, showing that C fibers are functionally mature in newborn lambs. In the second series of experiments, eight lambs pretreated with 25-50 mg/kg subcutaneous capsaicin did not exhibit any respiratory response to 10-50 microg/kg intravenous capsaicin injection, implicating C fibers in the response. Finally, in the above capsaicin-desensitized lambs, we observed that halothane-induced high-permeability pulmonary edema did not cause the typical response of sustained expiratory upper airway closure seen in the intact lamb. We conclude that functionally mature C fibers are present and responsible for a pulmonary chemoreflex in response to capsaicin intravenous injection in nonsedated lambs. Capsaicin pretreatment abolishes this reflex. Furthermore, the sustained expiratory upper airway closure observed during halothane-induced pulmonary edema in intact nonsedated lambs appears to be related to a reflex involving stimulation of pulmonary C fibers.

Animals↗
PubMed1998

Laryngeal and abdominal muscle electrical activity during periodic breathing in nonsedated lambs.

We recently reported that glottic closure was present throughout central apneas in awake lambs. The present study tested whether glottic closure was also observed during periodic breathing (PB). We attempted to induce PB in 21 nonsedated lambs on return from hypocapnic hypoxia to room air. Airflow and thyroarytenoid (a laryngeal constrictor, n = 16), cricothyroid (a laryngeal dilator, n = 10), and abdominal (n = 9) muscle electrical activity (EMG) were monitored continuously. PB was observed in 16 lambs, with apneic phases in 8 lambs. Thyroarytenoid muscle EMG was observed at the nadir of PB, either throughout apnea or with prolonged expiration during the lowest respiratory efforts. Phasic inspiratory cricothyroid muscle EMG and phasic expiratory abdominal EMG disappeared at the nadir of PB. Active glottic closure at the nadir of PB, without abdominal muscle contraction, could be a beneficial mechanism, preserving alveolar gas stores for continuing gas exchange during the apneic/hypopneic phase of PB. However, consequences of active glottic closure on ventilatory instability, either enhancing or reducing, are unknown.

Abdominal Muscles↗
PubMed1998

Coordination between glottic adductor muscle and diaphragm EMG activity in fetal lambs in utero.

It has previously been reported that active glottic adduction is present during prolonged apneas but absent during periods of breathing movements in fetal lambs in utero. The present study was aimed at examining the precise coordination between fetal breathing movements [diaphragm electromyographic (EMG) activity (Di EMG)] and glottic adduction [thyroarytenoid muscle EMG activity (TA EMG)]. Electrodes for electroencephalogram, eye movements, TA EMG, and Di EMG and an arterial catheter were surgically implanted in fetal lambs 123-142 days postconception. Polygraphic recordings were performed without sedation while the ewe breathed room air (n = 11) or various gas mixtures (hypoxia, n = 5; hyperoxia, n = 4; hypercapnia, n = 5; hypercapnia+hyperoxia, n = 5). Tonic TA EMG was observed throughout >90% of apneas (>6 s) in both non-rapid-eye-movement and rapid-eye-movement sleep, and when Di EMG frequency decreased in rapid-eye-movement sleep. In all but two fetuses, TA EMG was immediately inhibited when Di EMG appeared. Altering blood gases did not modify these results. In conclusion, Di EMG and TA EMG are well coordinated in late gestation in fetal lambs, except in a few cases. These findings may have consequences for understanding the pathogenesis of mixed/obstructive apneas of prematurity.

Animals↗
PubMed1997

Abolition of breathing rhythmicity in lambs by CO2 unloading in the first hours of life.

The mechanisms responsible for the maintenance of regular breathing after initiation of breathing at birth are still poorly understood. This study was designed to test the hypothesis that removing the chemical CO2 drive would abolish breathing rhythmicity in lambs in the first hours of life. A technique of graded CO2 removal through a veno-venous extracorporeal circuit was used in five unanesthetized lambs aged from 4 to 12 hours. In all lambs, CO2 unloading invariably resulted in sustained central apnea, after a decrease in Paco, of 6.9 +/- 5.7 Torr. We were unable to find a significant relationship between the decrease in PaCO2 and PaO2 (range 35-275 Torr) at onset of apnea. During apnea, the passage from behavioral quiet sleep to arousal or to active sleep was marked by transient and weak breathing movements. We conclude that the CO2 drive, but not the behavioral states, is a major factor for maintaining breathing rhythmicity in lambs in the first hours of life.

Animals↗
PubMed1997

Oral clindamycin and ciprofloxacin versus intramuscular ceftriaxone and oral doxycycline in the treatment of mild-to-moderate pelvic inflammatory disease in outpatients.

This multicenter, prospective, double-blind study compared the safety and efficacy of clindamycin and ciprofloxacin versus ceftriaxone and doxycycline in the treatment of outpatients with mild to moderate pelvic inflammatory disease (PID) diagnosed by laparoscopy. Samples taken from the endocervix, endometrium, and abdominal cavity before treatment and from the endocervix after treatment were cultured for aerobes, anaerobes, Neisseria gonorrhoeae, and Chlamydia trachomatis. Of the 138 patients enrolled, 131 were evaluable for efficacy. The most prevalent bacteria were streptococci, staphylococci, and Escherichia coli (among aerobes) and Bacteroides species and peptostreptococci (among anaerobes). N. gonorrhoeae was present in 2% (3) of the 131 evaluable patients, and C. trachomatis was in 11% (15). The clinical cure rate was 97% (65 of 67) in the clindamycin and ciprofloxacin group and 95% (61 of 64) in the ceftriaxone and doxycycline group. Side effects were similar in both groups. In conclusion, the two regimens for the outpatient treatment of mild to moderate PID were similarly effective and safe.

Administration, Oral↗
PubMed1996

Prolonged active glottic closure after barbiturate-induced respiratory arrest in lambs.

We recently showed that the glottis is actively closed throughout post-hyperventilation, hypocapnic central apnea in lambs. The present study was designed to test whether the glottis is also closed in non-hypocapnic central apnea. Twenty-seven lambs aged 2 to 30 days were intravenously injected with 325 mg of sodium pentobarbital, so as to obtain breathing arrest. Airflow was recorded via a facial mask and pneumotachograph, along with the electromyographic activity (EMG) of the thyroarytenoid muscle (TA, a glottic adductor). With the onset of apnea, continuous TA EMG appeared in a few seconds and rose rapidly. Brief inspiratory gasps were observed in eight lambs, and TA EMG was abruptly inhibited for the exact duration of the gasps. The continuous TA EMG then disappeared after 115 to 230 sec. We conclude that the glottis is actively closed during fatal non-hypocapnic central apnea in lambs. Our data suggest that active glottic closure occurs with major depression of central inspiratory drive.

Abdominal Muscles↗
PubMed1996

Inferior pharyngeal constrictor electromyographic activity during permeability pulmonary edema in lambs.

Newborn mammals exhibit an active expiratory upper airway closure during the first hours of extrauterine life. We have recently shown that permeability pulmonary edema led to active expiratory glottic closure in awake newborn lambs while hypoxia (inspired O2 fraction 8%; 15 min) did not. In the present study, we tested the hypothesis that expiratory glottic closure was accompanied by an increase in pharyngeal constrictor muscle expiratory electromyographic (EMG) activity. We studied seven awake nonsedated lambs aged 8-20 days. Airflow (facial mask + pneumotachograph), blood gases (arterial catheter), and EMG activity of both the thyroarytenoid muscle (a glottic adductor) and the inferior pharyngeal constrictor muscle were recorded before and after intravenous injection of halothane (0.05 ml/kg) to induce a permeability pulmonary edema. A central apnea (duration 15 s to 5 min) with continuous thyroarytenoid and inferior pharyngeal constrictor activity was observed within seconds after halothane injection. One lamb died despite rescuing maneuvers. An expiratory phasic thyroarytenoid and inferior pharyngeal constrictor muscle activity with simultaneous zero airflow gradually took place and, by 30 min after halothane injection, was present at each expiration in the six remaining lambs. Expiratory glottic and pharyngeal constrictor muscle EMG activity was subsequently present during the whole study period (1.5-5 h), even after correction of the initial hypoxia. Permeability lung edema was present at postmortem examination in all seven lambs. We conclude that a permeability pulmonary edema induced by intravenous halothane in non-sedated lambs enhances both glottic and pharyngeal constrictor muscle expiratory EMG. We hypothesize that expiratory contraction of the inferior pharyngeal constrictor muscle could participate in the active expiratory upper airway closure; this, in turn, might improve alveolocapillary gas exchange by increasing the end-expiratory lung volume.

Anesthetics, General↗
PubMed1995

Active expiratory glottic closure during permeability pulmonary edema in nonsedated lambs.

It has long been claimed that the active expiratory glottic closure observed in newborns, especially during hyaline membrane disease, is related to hypoxia. However, we recently showed that hypoxia does not lead to active expiratory glottic closure in nonsedated lambs. In this study, we test the hypothesis that glottic closure is related to an excess of lung water present at birth. We studied 17 nonsedated lambs after inducing a permeability pulmonary edema via intravenous of either oleic acid (8 lambs) or halothane (9 lambs). We recorded airflow via a facial mask and pneumotachograph, as well as the electromyographic activity (EMG) of the thyroarytenoid muscle (TA), a glottic adductor. Blood gases were measured in 8 lambs via a brachial artery catheter. We identified laryngeal expiratory airflow braking on the breath-by-breath computed flow-volume loop and TA expiratory EMG as evidence of active expiratory glottic adduction. After the injection of oleic acid or halothane, an active expiratory glottic closure was recorded in all lambs but 1, usually throughout the recording period (60 to 300 min). The active expiratory glottic closure was not inhibited after correction of the hypoxia. We conclude that, in nonsedated lambs, a permeability pulmonary edema induces an active expiratory glottic closure. We hypothesize that the expiratory glottic closure commonly observed in newborns could help to ameliorate the alveolocapillary gas exchange by reopening the flooded alveoli.

Animals↗
PubMed1993

A transplant of real life.

A case of steroid-resistant nephrotic syndrome with focal segmental glomerulosclerosis leading to renal failure in a 4-year-old girl is described by her mother, with special emphasis on the problems resulting from recurrence of this disease, with graft loss in three successive kidney transplants. This report chronicles the gradual evolution from a family's initial heavy dependence upon medical solutions to their ultimate primary emphasis upon spiritual values, with medicine seen as the support toward achieving the child's psychological well-being and spiritual growth. The physician's role in balancing medical decision making, non-medical alternatives, and demands on limited and precious resources in such difficult cases is discussed.

Child, Preschool↗
PubMed1992

Photodynamic effects of a cationic mesosubstituted porphyrin in cell cultures.

The photobiological activity of mesotetra (4N-methylpyridyl) porphine (T4MPyP) has been studied in a mammalian cell line in vitro. The uptake of T4MPyP to HeLa cells was examined using fluorescence microscopy. Under violet-blue exciting light, a nucleus-selective red fluorescence was detected. The intensity of fluorescence depended on drug concentration and incubation time, with a maximum relative emission at a concentration value of 10(-5) M for 20 min. The photosensitivity of HeLa cells incubated with T4MPyP under previous conditions and subsequently exposed to variable doses of visible light has been examined. Cell toxicity was evaluated as the surviving fraction, using the trypan blue staining test. The extent of cellular damage was found to be dependent on irradiation time, with a lethal damage after 8 min of light exposure. Cellular DNA-photodamage was studied under sublethal conditions (2 min of irradiation) by the use of the micronucleus test. The number of micronuclei, in these conditions, increased with regard to baseline levels.

Cell Nucleus↗
PubMed1991

Intra-arterial cisplatin given prior to surgery in osteosarcoma: grade of necrosis and size of tumor as major prognostic factors.

From January 1983 to August 1987, 29 evaluable patients with high-grade osteosarcoma were treated in our institution with preoperative intra-atrial cisplatin, 100 mg/m2 every 14 days for three courses. Surgery was done on day 42. Surgery consisted of limb salvage in six, amputations in 15, and disarticulations in eight. Postoperative chemotherapy included Adriamycin (ADR), 45 mg/m2 for 2 days every 6 weeks, alternated with cisplatin 120 mg/m2 every 6 weeks. The nephrotoxicity (18 out 29) was reversible in all cases. Cardiotoxicity was prominent; it was observed in 31% of patients. In six, there was congestive heart failure, but there were no fatal cases. The hematological toxicity was severe. There were three patients with fatal infections who had no evidence of disease after they had finished treatment. Seventeen of 29 patients (58.6%) were good responders and showed 60-100% tumoral necrosis after intra-atrial cisplatin. The 6-year, relapse-free survival rate was 58.6%--70.5% for the good responders and 41.6% for the poor responders (p less than 0.05). The size of the tumor was the other important prognostic factor. The rate of 6-year, relapse-free survival was 73.6% for small tumors (those measuring less than 100 cm2) and 33.3% for large tumors (p less than 0.05).

Adolescent↗
PubMed1988

Activities of creatine kinase and its isoenzymes in serum in various skeletal muscle disorders.

We studied possible correlations between anatomopathological and clinical features and the values for total creatine kinase (CK; EC 2.7.3.2) and its isoenzymes, including the proportion of CK-MB, in a population displaying several neuromuscular pathologies. Although we observed no specific isoenzyme pattern associated with the different myopathies, we found isoenzyme analysis useful in studying the histopathological evolution of illness. We also considered whether the pathology was regenerative or nonregenerative, and what type of fiber (I or II) was involved. High CK-MB percentages (greater than 6%) were associated with regenerative and type I fiber myopathies, with regenerative type tissues being the principal factor associated with an increasing proportion of CK-MB. Studying the changes in CK-MB percentage in serum appears to be useful in discriminating neuromuscular from myocardial pathologies.

Adolescent↗