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Biomedical subjects

D Garcia

Publications and source records attributed to D Garcia.

At least 19 recordsLinked to original sources
PubMed1992

Cerebral acid buffering capacity at different ages measured in vivo by 31P and 1H nuclear magnetic resonance spectroscopy.

Cerebral acidosis occurring during ischemia has been proposed as one determinant of tissue damage. Newborn animals appear to be less susceptible to ischemic tissue damage than adults. One possible component of ischemic tolerance could derive from maturational differences in the extent of acid production and buffering in newborns compared to adults. The purpose of this study was to measure the dependency of acid production on the blood plasma glucose concentrations and acid buffering capacity of piglets at different stages of development. Complete ischemia was induced in 29 piglets ranging in postconceptual age from 111 to 156 days (normal term conception, 115 days). Brain buffering capacity during the first 30 min of ischemia was quantified in vivo, via 31P and 1H nuclear magnetic resonance (NMR) spectroscopy, by measuring the change in intracellular brain pH for a given change in the concentration of compounds that contribute to the production of hydrogen ions. Animals from all four age groups showed a similar linear correlation between preischemia blood glucose concentration and intracellular pH after 30 min of ischemia. For each animal the slope of the plot of intracellular pH versus cerebral buffer base deficit was used to calculate the buffer capacity. Using data obtained over the entire 30 min of ischemia, there was no difference in the mean buffer capacity of the different age groups, nor was there a significant correlation between buffer capacity and age. However, there was a significant increase in buffer capacity for the intracellular pH range 6.6-6.0, compared to 7.0-6.6, for all age groups. No significant differences in buffer capacity for these two pH ranges were observed between any of the age groups. Acid buffering capacity was also measured by performing pH titrations on brain tissue homogenized in the presence of inhibitors of glycolysis and creatine kinase. Plots of homogenate pH versus buffer base deficit showed a nonlinear trend similar to that seen in vivo, indicating an increase in buffer capacity as intracellular pH decreases. A comparison of newborn and 1-month-old brain tissue frozen under control conditions or after 45 min of ischemia revealed no differences that could be attributed to age and a slight decrease in buffer capacity of ischemic brain compared to control brain tissue homogenates. There was no difference between the brain buffering capacity measured in vivo using 31P and 1H NMR and that measured in vitro using brain homogenates.

Acids↗
PubMed1992

Alpha 2-receptor-mediated inhibition of intraluminal release of gastric somatostatin in anaesthetized rats.

The aim of the present study was to investigate how the sympathetic nervous system affects the vagally induced intragastric release of somatostatin and gastrin. Experiments were performed on anaesthetized rats in which the stomach was perfused with a dextrane solution (pH approximately 5.9) or dextrane buffer (pH 7.4). pH as well as gastrin and somatostatin levels were measured in the gastric perfusate when it had passed the stomach. Vagal stimulation caused a decrease in perfusate pH and an increase of the intraluminal output of gastrin and somatostatin when the stomach was perfused with the dextrane solution pH 5.9. Pretreatment with phentolamine (1 mg kg-1) significantly increased and pretreatment with clonidine (60 micrograms kg-1 h-1) significantly decreased somatostatin release caused by vagal stimulation, whereas gastrin levels remained largely unchanged. The effect of clonidine persisted in rats pretreated with indomethacin (5 mg kg-1), which per se potentiates the vagally induced luminal somatostatin release. When the stomach was perfused with the dextrane buffer pH 7.4, basal gastrin levels were significantly higher than during perfusion with the solution pH 5.9, whereas somatostatin levels remained unchanged. Neither somatostatin nor gastrin levels increased following vagal stimulation during gastric perfusion with the dextrane buffer pH 7.4. However, following pretreatment with phentolamine somatostatin levels increased during these conditions.

Anesthesia↗
PubMed1992

Impact of short-term oral steroid use upon children's school achievement and behavior.

Physicians need clarification of whether the temporary use of adrenal corticosteroids to abort acute asthma can adversely effect school achievement and behavior problems. Nineteen nonsteroid-dependent asthmatic children were given prednisone orally while all other medications were kept constant. Five days later, when they were seen in the physician's office, an academic achievement test was administered to the child; and the child, a parent, and a teacher completed behavior rating surveys. After 2 weeks off the steroids the child returned to the physician's office and the achievement test and rating scales were completed again. There was no significant difference between the achievement test scores and behavior ratings in school or at home under the two conditions. Short-term use of oral steroids does not impair children's basic academic skills nor their behavior at school or home.

Administration, Oral↗
PubMed1991

Colonic motility: electric and manometric description of mass movement.

"Mass movement" was described at the beginning of the century by radiologists who occasionally observed how, during their explorations, barium was transported suddenly from one section of the colon to another. In the present study we wanted to center our attention on electromechanical activities accompanying large evacuations via the colostomy, as we believe that they are an expression in myoelectric and pressure terms of the "mass phenomenon" described by radiologists. To do this, we designed an electromyographic recording probe to which we attached a conventional microtransducer probe, joining them by suction. With this method we made 24-hour recordings in eight patients with sigmoid colostomy. We witnessed five large evacuations. When the electric and pressure activities that occurred a few minutes before the evacuation were analyzed, we observed that there were two clearly different phases. The first, which we call "Preliminary Phenomenon," consists of a series of contractions and spiking potentials averaging 5.6 minutes (SD 2.22); after this the "Big Contraction" appears, with mean pressure values of 127 mm Hg (SD 38.77) and mean electric values of 10.6 mV. The duration of this phenomenon averaged 24.93 seconds (SD 6.19), recorded almost simultaneously at the three recording sites studied. There is no doubt that these electro-pressure phenomena resulted in a mass transport, as we observed an intense evacuation via the colostomy in the five patients.

Colon↗
PubMed1991

Process, costs, and outcomes of community-based prenatal care for adolescents.

An evaluation of a community-based prenatal care program for teens compared 180 adolescent clients with a sample of adolescents matched on age and year of delivery who received care through a traditional prenatal care program at a university medical center. Evaluation criteria describing the process of receiving care were the mean number of prenatal visits, nonscheduled outpatient visits, nonstress tests, ultrasounds, and inpatient days during pregnancy. The two programs were significantly different as measured by these criteria. Outcome criteria included gestational age, birthweight, the percentage of infants requiring neonatal intensive care, and the percentage of clients with maternal complications. A multivariate analysis showed no statistically significant differences in these outcomes. The average cost of resources consumed during prenatal care for the study group was 41% that of controls.

Adolescent↗
PubMed1991

The effect of age on glucose-modulated cerebral agonal glycolytic rates measured in vivo by 1H NMR spectroscopy.

The purpose of this study was to investigate the effect of plasma glucose concentration on cerebral agonal glycolytic rates in piglets of different ages. Twenty-four piglets were divided into four different age groups corresponding to 113, 121, 128, and 145 d postconception (normal gestation = 115 d). For each group the agonal glycolytic rate was measured by monitoring the rate of cerebral lactate accumulation after total ischemia. Ischemia was induced by cardiac arrest, and the rate of lactate formation was measured in vivo using proton nuclear magnetic resonance spectroscopy. Before cardiac arrest, the blood plasma glucose concentration for individual piglets was adjusted to a specific value in the range 1-30 mM. The dependence of agonal glycolytic rate upon blood glucose concentration was analyzed for each age group, using the Michaelis-Menten equation to evaluate Vmax, the maximal rate of glucose utilization, and Km the concentration of plasma glucose at which the half maximal rate of utilization occurs. Vmax for the two youngest age groups of piglets had significantly different (p less than 0.05) values compared with each other (1.38 +/- 0.17 and 1.92 +/- 0.64 mumol.g-1.min-1, respectively) and with the two older groups of animals (2.99 +/- 0.52 and 3.42 +/- 0.65 mumol.g-1.min-1, respectively). The Km values determined for the two youngest age groups (0.79 +/- 0.70 and 1.79 +/- 0.33 mM, respectively) also were significantly lower than for the two older age groups (4.96 +/- 2.90 and 4.82 +/- 2.96 mM, respectively). We conclude that throughout the first 2 wk of life there are marked increases in the cerebral glycolytic capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Evaluating needle exchange: do distributed needles come back?

We employed capture-recapture methods as a strategy for evaluating needle exchange. Needles distributed by the exchange at two time periods were marked with color coded bands indicating the date and site of distribution. Half of the marked needles (2,068/4,239) returned within two weeks of distribution, and 61 percent (2,593/4,239) returned during the study period. The rate of return for stationary exchange sites (63 percent) was greater than that for roving/mobile sites (51 percent; chi 2 = 28.6, p less than .001). Of all needles returned, 87 percent (2,248/2,593) returned to the site of original distribution.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Cytotoxicity of tetraplatin and cisplatin for human and rodent cell lines cultured as monolayers and multicellular spheroids.

The cytotoxicity of tetraplatin (dl-trans), its d- and l-isomers, and cisplatin for four human tumor cell lines (myeloma 8226, ovarian 2008, A2780, and OVCAR-3), their cisplatin-resistant variants, and three rodent cell lines (V79, EMT6/Ro, and L1210) were compared. Tetraplatin was more, or equally as, potent as cisplatin for the human cell lines and for L1210 but was clearly less potent for V79 and EMT6/Ro. The d-trans tetraplatin was more potent than the l-trans. Cisplatin resistant human tumor cells were less resistant to tetraplatin. On comparing sensitivity of V79 and EMT6/Ro cells in two growth models, we observed that all of the platinum compounds were more cytotoxic to cells in multicellular spheroids than in exponentially growing monolayers. Uptake studies, however, showed that tetraplatin was more cytotoxic to spheroids because spheroids accumulated more drug than monolayers.

Animals↗
PubMed1991

Cisplatin in advanced cancer of the cervix: an update.

Cisplatin is the single most active cytotoxic agent in the treatment of patients with recurrent or metastatic squamous cell cancer of the cervix; no other standard drug has been associated consistently with objective response rates of 25% or higher. However, cervical cancer is a relatively drug-resistant disease and prolonged cisplatin treatment appears to induce multiple mechanisms of tumor resistance. The majority of objective responses to cisplatin are partial and relatively short-lived and, therefore, have little impact on survival duration. Complete responses to cisplatin are seen predominantly in patients with extrapelvic metastases rather than pelvic recurrences. This article examines the role of cisplatin in the management of advanced cervical cancer with emphasis on its efficacy in the following circumstances: as a single agent; in combination with other cytotoxic drugs; in previously treated patients; and when administered before surgery or before or concurrent with definitive radiation therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Comparison of reactogenicity and antigenicity of M37 rotavirus vaccine and rhesus-rotavirus-based quadrivalent vaccine.

90 Venezuelan infants aged 10-20 weeks were randomly allocated to four groups which received one of the following: the M37 vaccine (1 x 10(4) pfu [plaque-forming units]); quadrivalent rotavirus vaccine (1 x 10(4) pfu each of serotype 3 rhesus rotavirus [RRV] and human rotavirus-RRV reassortants of serotypes 1, 2, and 4); balanced quadrivalent vaccine consisting of 1 x 10(4) pfu of serotype 1 and 3 components but 5 x 10(4) pfu of serotype 2 and 4 components; or placebo. The frequencies of transient febrile responses in these four groups were 20%, 27%, 30%, and 9%. 50% of 22 infants tested who received M37 vaccine showed a serum rotavirus IgA antibody response, compared with 74% of the 23 quadrivalent and 86% of the 22 balanced-quadrivalent recipients. 64% of the M37 recipients showed a neutralising antibody response to M37; 27% showed such responses to human serotype 1 Wa strain and 27% to serotype 4 neonatal strain ST3. 17-39% of the quadrivalent recipients and 27-41% of the balanced-quadrivalent recipients showed neutralising antibody responses to serotypes 1-4. 70-73% of the quadrivalent and balanced quadrivalent groups also showed neutralising antibody responses to RRV.

Antibodies, Viral↗
PubMed1990

Prospective study of diarrheal diseases in Venezuelan children to evaluate the efficacy of rhesus rotavirus vaccine.

The efficacy of a rhesus rotavirus vaccine (MMU 18006, serotype 3) against infantile diarrhea was evaluated by active home surveillance of a group of 320 children 1-10 months of age in Caracas, Venezuela. During a 1 year period following oral administration of vaccine or placebo under a double-masked code, over 600 diarrheal episodes were detected. Etiologic studies revealed that heat-stable toxin (ST) producing enterotoxigenic E. coli (ETEC) was the most common diarrheal agent detected (34%) followed by enteropathogenic E. coli (EPEC, 10.9%), heat-labile toxin (LT) producing ETEC (7.6%), rotavirus (6.9%), Cryptosporidium (4.8%) and Campylobacter (1.3%). ST-producing ETEC were also recovered from over 20% of control stool specimens obtained during diarrhea-free periods, whereas EPEC, rotavirus, Cryptosporidium, and Campylobacter were rarely detected in such control specimens. Rotavirus was responsible for about one-half of the more severe cases of diarrhea. Twenty-two of 151 infants who received placebo (14.6%) and eight of 151 receiving a 10(4) PFU dose of vaccine (5.3%) had rotavirus diarrhea during the follow-up period for an efficacy level of 64% against any rotavirus diarrhea. However, vaccine efficacy reached 90% against the more severe cases of rotavirus diarrhea and was noticeably high in the 1-4 month age group. Serotypic analysis of the rotaviruses detected suggests that the resistance induced by the vaccine was type specific since significant protection was only evident against serotype 3 rotaviruses. A 10(3) PFU dose tested initially in 18 children did not appear to protect against rotavirus diarrhea.

Complement Fixation Tests↗
PubMed1990

Clinical studies of a quadrivalent rotavirus vaccine in Venezuelan infants.

Phase I studies of an oral quadrivalent rotavirus vaccine were conducted in 130 Venezuelan infants 10 to 20 weeks of age. The vaccine consists of a mixture of equal amounts of rhesus rotavirus (RRV) vaccine (serotype 3 [VP7]) and each of three human rotavirus-RRV reassortant strains: D x RRV (serotype 1 [VP7]), DS1 x RRV (serotype 2 [VP7]), and ST3 x RRV (serotype 4 [VP7]). Three different doses of the quadrivalent vaccine (0.25 x 10(4), 0.5 x 10(4), and 10(4) PFU of each component) were evaluated sequentially for safety and antigenicity in placebo-controlled, double-blind trials. Starting the day after vaccination, the infants were monitored by daily home visits for 7 days. Only minor reactions were observed during this period; these were limited to mild transient febrile episodes which began day 2 or 3 after vaccination and lasted 1 to 2 days in 15 to 30% of the infants. Serological studies demonstrated that 68 to 96% of the infants developed a rotavirus serum immunoglobulin A response following vaccination. However, when tested by plaque reduction neutralization assay against individual human rotavirus serotype 1, 2, 3, or 4, the response rates ranged from 4 to 23% with the low dose, 21 to 33% with the medium dose, and 32 to 58% with the high dose. Most (73 to 79%) infants developed neutralizing antibodies to RRV following administration of each dose schedule. Vaccine virus shedding was analyzed by utilizing tissue culture isolation of virus from stool. All of the infants who received the lower of medium dose and 89% of those fed the high dose shed one or more components of the vaccine. Analyses of rotavirus serotypes isolated from the stool of infants who received the 0.25 x 10(4) -PFU dose revealed that DS1 x RRV was the most commonly shed vaccine component, followed by RRV, D x RRV, and ST3 x RRV in that order.

Administration, Oral↗
PubMed1990

Identification of human rotavirus serotype by hybridization to polymerase chain reaction-generated probes derived from a hyperdivergent region of the gene encoding outer capsid protein VP7.

We have synthesized 32P-labeled hybridization probes from a hyperdivergent region (nucleotides 51 to 392) of the rotavirus gene encoding the VP7 glycoprotein by using the polymerase chain reaction method. Both RNA (after an initial reverse transcription step) and cloned cDNA from human rotavirus serotypes 1 through 4 could be used as templates to amplify this region. High-stringency hybridization of each of the four probes to rotavirus RNAs dotted on nylon membranes allowed the specific detection of corresponding sequences and thus permitted identification of the serotype of the strains dotted. The procedure was useful when applied to rotaviruses isolated from field studies.

Antigens, Viral↗
PubMed1990

[Psychological effects of previous treatment experiences with neuroleptics].

Stable attitudes towards illness and treatment and a high compliance with a 5-week low dose neuroleptic treatment (with/without anticonvulsant adjuvant therapy) were observed in 18 inpatients with schizophrenic disorders (ICD-9, DSM-III-R). Patients having previously received neuroleptics showed more compliant attitudes and greater satisfaction with the treatment, and complained less often about side effects. Noncompliant attitudes were related to dissatisfaction with treatment and self-rated depressed mood. Results of this pilot study are discussed, considering methodological problems and possible therapeutic implications.

Adult↗