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Biomedical subjects

D Garcia

Publications and source records attributed to D Garcia.

At least 73 records · Page 4Linked to original sources
PubMed1994

Evaluation of the antigenicity and reactogenicity of varying formulations of the rhesus rotavirus-based quadrivalent and the M37 rotavirus vaccine candidates.

Three phase I trials of the rhesus rotavirus (RRV)-based quadrivalent vaccine [composed of serotype 3 (RRV), and serotypes 1 (D x RRV), 2 (DS1 x RRV), and 4 (ST3 x RRV) human rotavirus x RRV reassortants] and the M37 (nursery strain) rotavirus vaccine candidates were conducted in an attempt to find a safe and optimally antigenic formulation. Infants 10-20 weeks old received, in trial I, 1) the quadrivalent vaccine as two separate bivalent doses (1 x 10(4) PFU each of D x RRV and RRV, followed 4 weeks later by 1 x 10(4) PFU each of DS1 x RRV and ST3 x RRV) or 2) placebo; in trial II, 1) one dose of quadrivalent vaccine (10(4) PFU of each component), or 2) two doses of quadrivalent vaccine, or 3) a 10(4) PFU dose of M37 vaccine, or 4) M37 vaccine followed by the quadrivalent vaccine, or 5) placebo; in trial III, 1) a dose of a higher-titered quadrivalent vaccine (10(5) PFU of each component), or 2) two doses of higher titered quadrivalent vaccine, or 3) a dose of higher titered M37 vaccine (10(5) PFU) or 4) two doses of M37 vaccine (10(5) PFU), or 5) M37 vaccine (10(5) PFU) followed by the higher titered quadrivalent vaccine, or 6) placebo. A mild, transient fever during the first week postvaccination was associated with the bivalent or quadrivalent vaccines but not with the M37 vaccine. Fourfold or greater serum IgA ELISA responses to rotavirus were observed in 48-92% of the infants receiving quadrivalent vaccine and in 32-50% of those receiving M37 vaccine.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Viral↗
PubMed1994

A PCR-based genetic map for human chromosome 3.

Oligonucleotide primers for 125 simple sequence repeat microsatellite-based genetic markers have been assayed by polymerase chain reaction (PCR) in the CEPH reference family panel. These microsatellites include 101 dinucleotide repeats as well as 24 new tetranucleotide repeats. The average heterozygosity of this marker set was 72.4%. Genetic data were analyzed with the genetic mapping package LINKAGE. A subset of these microsatellite markers define a set of 56 uniquely ordered loci (> 1000:1 against local inversion) that span 271 cM. Sixty-seven additional loci were tightly linked to markers on the uniquely ordered map, but could not be ordered with such high precision. These markers were positioned by CMAP into confidence intervals. One hundred thirteen of the microsatellite markers were also tested on a chromosome 3 framework somatic cell hybrid panel that divides this chromosome into 23 cytogenetically defined regions, integrating the genetic and physical maps of this chromosome. The high density, high heterozygosity, and PCR format of this genetically and physically mapped set of markers will accelerate the mapping and positional cloning of new chromosome 3 genes.

Animals↗
PubMed1994

Structure and function of the tetraheme cytochrome associated to the reaction center of Roseobacter denitrificans.

We have characterized the tetrahemic RC bound cytochrome isolated from the quasi-photosynthetic bacterium Roseobacter denitrificans in terms of absorption spectrum, redox property and orientation with respect to the membrane plane. The heme, designated H1, which possesses the highest redox midpoint potential (+290 mV), absorbs at 555 nm. Its plane makes an angle of 40 degrees with the membrane plane. The second high potential heme, H2 (+240 mV), peaks at 554 nm and makes a tilt of 55 degrees with the membrane. The two low potential hemes, L1 and L2, present a similar and rather high redox midpoint potential (+90 mV). They absorb at 553 nm and 550 nm. One of these hemes is oriented at 40 degrees while the other makes an angle of 90 degrees with the membrane plane. The soluble cytochrome c551 completes the cyclic electron transfer between the RC and the bc1 complex. Both the oxidation and the re-reduction of cytochrome c551 are diffusible processes. Under semi-aerobic conditions, one of the low potential hemes is photo-oxidized under illumination but only extremely slowly re-reduced. This explains the requirement of high aerobic conditions for growth of Roseobacter denitrificans cells in the light.

Bacteria↗
PubMed1994

A comparison of the VP7 gene sequences of human and bovine rotaviruses.

The sequences of the gene encoding VP7 (the major outer capsid protein) from one bovine and three human rotavirus strains were determined because of their unusual VP7 specificities. Two of the human strains (PA 169 and PA 151) had VP7 serotype 6 specificity whereas the two other strains, recovered from a child (HAL 1166) and a calf (678) belonged to VP7 serotype 8. The serotype 8 strains exhibited a high degree of sequence conservation when compared with each other and with other serotype 8 strains previously sequenced. The serotype 6 human strains shared a greater degree of sequence similarity with previously reported serotype 6 bovine strains than with other rotavirus serotypes; however the degree of sequence similarity among PA 169, PA 151 and the bovine strains was lower than had been previously reported for strains belonging to the same serotype. The demonstration of rotavirus serotypes that are shared between human and animal species supports the concept that interspecies transmission occurs and may play a role in rotavirus evolution.

Amino Acid Sequence↗
PubMed1994

Modest hypothermia provides partial neuroprotection for ischemic neonatal brain.

Hypothermia is a frequent occurrence in newborns, and thermoregulatory management is a fundamental part of medical stabilization. Although modest reduction in brain temperature (2-3 degrees C) before ischemia provides neuroprotection in adults, the effect of modest hypothermia on immature brain has not been examined. Nine-day-old swine were exposed to 15 min of incomplete global brain ischemia, with intraischemic rectal temperatures of either 38.3 +/- 0.4 degrees C (n = 10, normothermic) or 35.4 +/- 0.5 degrees C (n = 10, hypothermic). The relationship between rectal and brain temperature was delineated in preliminary experiments on four swine. Animals with intraischemic rectal temperatures maintained at either 39.5 degrees C or 35.5 degrees C were associated with a similar magnitude of difference in brain temperature. Therefore, rectal temperature was used to monitor brain temperature for 20 animals studied subsequently. Ischemia was induced by combining neck compression with hemorrhagic hypotension and resulted in similar group values for mean arterial pressure and changes in pH and blood gases at the completion of ischemia. A clinical overall performance score and brain tissue structure were evaluated after 72 h (or earlier if animals died prematurely). Hypothermic animals had less severe stages of impairment compared with the normothermic group (p = 0.023). Hypothermic piglets had less histologic damage in the neocortex at 0.5 cm beneath the brain surface (p = 0.048), the caudate nucleus (p = 0.038), and the pons/midbrain (p = 0.04) and the same direction of effect in neocortex at 1 cm beneath the surface (p = 0.07) and the cerebellum (p = 0.07) as compared with normothermic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Primary structure of Chromatium tepidum high-potential iron-sulfur protein in relation to thermal denaturation.

A high-potential ferredoxin (HiPIP) has been purified from the thermophilic purple sulfur bacterium Chromatium tepidum. Most of the properties of this protein, including absorption and electron paramagnetic resonance spectra as well as redox potential, are identical to those of the similar protein isolated from the mesophilic organism Chromatium vinosum. The similarity extends to the amino acid sequences, which share 74 of the 83 residues composing the primary structure of C. tepidum HiPIP. The latter has been determined by sequencing overlapping peptides and precisely measuring the molecular mass of the holoprotein (9136 Da) by electrospray ionization mass spectrometry. The most significant difference between these sequences involves a stretch of 8 amino acids, which is shortened by two residues and notably changed in C. tepidum HiPIP. This region had been identified in the three-dimensional structure of C. vinosum HiPIP as both a link between two strands of a twisted beta sheet coordinating the [4Fe-4S] cluster and an area of strong interaction of the molecule with the solvent. These data have been used to discuss the molecular basis for the slightly improved thermal stability of C. tepidum HiPIP, as compared to C. vinosum HiPIP. Based on the physiological differences distinguishing C. tepidum from other small-sized Chromatiaceae, the presence of an abundant HiPIP in C. tepidum indicates that involvement as electron acceptor for the previously proposed thiosulfate oxidizing activity in C. vinosum may not be the sole function in all purple sulfur bacteria.

Amino Acid Sequence↗
PubMed1993

Analysis of patient age as an independent prognostic factor for survival in a phase III study of cisplatin-cyclophosphamide versus carboplatin-cyclophosphamide in stages III (suboptimal) and IV ovarian cancer. A Southwest Oncology Group study.

BACKGROUND: The purpose of this study was to evaluate the effect of age (i.e., less than 65 years or 65 years of age and older) on survival in a recently completed phase III Southwest Oncology Group study in ovarian cancer patients. METHODS: Multivariate and univariate regression analyses were used to identify independent prognostic factors of survival in 342 patients with previously untreated Stage III (suboptimal) or Stage IV ovarian cancer who participated in a randomized, phase III study of intravenous (I.V.) carboplatin 300 mg/m2 plus I.V. cyclophosphamide 600 mg/m2 versus I.V. cisplatin 100 mg/m2 plus I.V. cyclophosphamide 600 mg/m2 every 4 weeks for six courses. RESULTS: Multivariate regression analysis showed the following variables to be independent prognostic factors of survival: age (P = 0.04); performance status (P = 0.004); disease stage (P = 0.03); and race (P = 0.05). Patients under 65 years of age survived significantly longer than those 65 years or older, especially patients with a performance status of 2. Patients with a baseline performance status of 0-1 survived longer than patients with a performance status of 2, and Stage III patients longer than those with Stage IV disease. An unexpected finding was that white patients survived significantly longer than black patients, regardless of age, performance status, or stage of disease. Carboplatin-cyclophosphamide-treated patients experienced similar survival and significantly less nausea and emesis, renal toxicity, hearing loss, tinnitus, neuromuscular toxicities, and alopecia. CONCLUSIONS: Ovarian cancer patients with advanced disease who are 65 years of age or older and/or with a performance status of 2 have significantly decreased survival compared to their younger and/or less debilitated counterparts. Carboplatin-cyclophosphamide is the recommended treatment (rather than cisplatin-cyclophosphamide), especially for older or debilitated patients because it is associated with less toxicity and similar survival.

Adult↗
PubMed1993

Energy reserves and utilization rates in developing brain measured in vivo by 31P and 1H nuclear magnetic resonance spectroscopy.

Age-related changes in cerebral energy utilization were examined in swine, a species whose maximal rate of development is known to occur in the perinatal period. Interleaved in vivo 31P and 1H nuclear magnetic resonance spectroscopy was used to measure the rates of change in cerebral concentrations of phosphocreatine (PCr), nucleoside triphosphates, and lactate following complete ischemia, induced via cardiac arrest, in a total of 19 newborn, 10-day-old, and 1-month-old piglets. Preischemic concentrations of these three metabolites plus glucose and glycogen were determined in a separate experiment on 12 piglets whose brains were funnel-frozen in situ. The rate constants for the PCr and ATP decline and lactate increase were determined by nonlinear regression fits to the experimental data, assuming first-order kinetics. The rate constants and preischemic metabolite concentrations were used to calculate the initial flux of high-energy phosphate equivalents (approximately P), which was used as an estimate of cerebral energy utilization at the point when ischemia was initiated. Cerebral energy utilization equaled 6.5 +/- 1.9, 9.5 +/- 3.2, and 15.1 +/- 3.2 mumol approximately P/g/min in newborn, 10-day-old, and 1-month-old piglets, respectively. Within each age group the energy utilization rate was not altered by hyperglycemia-induced increases in cerebral energy reserves, but during hypoglycemia cerebral energy utilization rates decrease. The slope of approximately P versus time decreased with the duration of ischemia, indicating that cerebral energy utilization rates decrease after the first few minutes of ischemia. Newborn piglets had higher cerebral energy utilization rates compared with literature values for newborn rats and mice. This is consistent with the concept that newborns from a species with a perinatal stage of maximal growth and development will have higher cerebral energy demands compared with newborns from a species such as rodents, whose maximal growth occurs postnatally. However, this conclusion remains tentative because literature cerebral utilization rates estimated from the initial slope of approximately P-versus-time plots tend to underestimate the true rate, since the assumption of continued linearity may not be valid for the interval chosen.

Animals↗
PubMed1993

Distribution of VP4 gene alleles in human rotaviruses by using probes to the hyperdivergent region of the VP4 gene.

The rotavirus VP4 protein elicits the production of neutralizing antibodies and is known to play a role in inducing resistance to disease. At least five human rotavirus VP4 gene alleles have been described on the basis of antigenic polymorphism and/or nucleotide sequence differences. In the present study, we developed cDNA probes directed at the hyperdivergent region of the VP4 gene of the five described human rotavirus VP4 alleles (Wa, DS1, M37, AU228, and 69M) and used them in hybridization assays with human rotavirus strains from Latin America and Europe to determine the distribution of the VP4 gene alleles in nature. The Wa-like allele was detected most frequently, occurring in 57% of the 402 rotavirus strains tested, and the DS1-like allele was the next most common, occurring in 14% of the strains tested. The M37- and AU228-like alleles were detected in only 4 and 3% of the rotavirus strains tested, respectively, whereas the 69M-like VP4 gene allele was not detected. Several rotavirus strains from Europe did not react with any of the VP4 gene probes, although they did hybridize to a probe generated from a representative strain from the group. These data indicate the global distribution of various VP4 gene alleles and raise the possibility that other, unrecognized human VP4 alleles exist in nature because almost one-fourth of the strains could not be classified into any of the established VP4 groups.

Alleles↗
PubMed1993

The effect of hypercarbia on age-related changes in cerebral glucose transport and glucose-modulated agonal glycolytic rates.

This study examined the effect of hypercarbia on cerebral agonal glycolytic rates and brain lactate accumulation after complete ischemia induced by cardiac arrest. Before cardiac arrest, the blood plasma glucose concentration in seven newborn (113 d postconception; normal gestation, 115 d) and seven 1-mo-old (144 d postconception) piglets was adjusted to a specific value (range, 1 to 64 mM), and then inspired ventilation gases were changed to 10:50:40 CO2:O2:N2 for 20 min. The agonal glycolytic rate was measured by monitoring the rate of cerebral lactate formation in vivo using proton nuclear magnetic resonance spectroscopy, and postmortem brain lactate concentrations were measured biochemically in tissue extracts obtained 40 to 45 min after cardiac arrest. These data were compared with 21 normocarbic piglets of similar age, nine examined as part of the present study and 12 examined previously (Corbett RJT, Laptook AR, Ruley JI, Garcia D: Pediatr Res 30:579-586, 1991). There was a nonlinear relationship between the final postmortem brain lactate concentration and preischemia blood plasma glucose concentration that was most prominent in newborn piglets and previously had gone unnoticed. When analyzed using a steady-state model for glucose transport, this relationship revealed that normocarbic newborns had a lower preischemia affinity constant for the transport mechanism for glucose (2.8 +/- 1.5 mM) and lower cerebral glucose utilization rate relative to transport rate (0.12 +/- 0.04), compared with 1-mo-olds (4.5 +/- 1.4 mM and 0.30 +/- 0.03, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Lactic↗
PubMed1993

[Iatrogenic complications of paraganglioma of the jugular foramen].

Twenty-eight cases of tumours of the paraganglioma of the foramen jugulare arising from the jugular foramen were treated from 1982 to 1990. The follow-up and the iatrogenic effect of embolization, surgery and radiotherapy were studied. Routine pre-operative embolisation has changed the therapeutic approach to these tumours although a certain number of mainly neurological complications still occur (32% of the cases with 18% of major accidents) especially when the internal carotid component must be excluded. Current oto-neurosurgical techniques allow wider and more complete exeresis of the tumour but often lead to neurological deficits involving the facial nerve (45%), the mixed nerves (32%) and/or the XII (18%). These deficits occur due to unavoidable sacrifice or peroperative manipulation. Radiotherapy is an essential therapeutic possibility with only minor complications and can be proposed in cases of inoperable or relapsing tumours or after an incomplete surgical exeresis. Our critical analysis led us to propose the present indications for surgery. Surgery is indicated in patients with two or more of the following criteria: age less than 55, unilateral tumour, a tumour considered to be inoperable, preoperative otoneurological manifestations, invasion of the posterior fossa. In the other cases, radiotherapy remains the indicated therapy. It is effective and should be used more often for inoperable tumours of the para-jugular lymph nodes, for relapses or after incomplete surgical exeresis.

Adult↗
PubMed1993

[Cholesteatoma of the middle ear with closed tympanic membrane in children. Apropos of 8 cases].

Among 30 children with cholesteatoma undergoing surgery at the Bicetre Hospital between 1985 and 1990, 8 had intact tympanic membranes. Since this represents a larger portion of the patient population than would be expected from previously published data, we under-look a critical analysis of the clinical findings. Among these 8 cases, 2 corresponded to the criteria of congenital cholesteatoma with no history of otitis or trauma and 3 corresponded to acquired types with histories of ventilatory intubation, myringoplasty and accidental trauma. Finally, 3 cases were possibly of mixed origin with lesions typical of congenital epithelial rests and a history of commonplace era infections. Based on these observations, the authors review the clinical characteristics and pathogenesis of congenital cholesteatoma and evoke the etiologic impact of trauma, particularly iatrogenic events such as myringoplasty and ventilatory intubation.

Child↗
PubMed1993

Multianalyte assay system developed for drugs of abuse.

A simple, 10-min immunoassay system has been developed that simultaneously screens for five different classes of drugs of abuse in a urine sample. This system tests for amphetamines, cannabinoids, cocaine metabolites, opiates, and phencyclidine, and each assay has a specific preset cutoff concentration. Accuracy is > 99% for reporting positive or negative results for samples with 200% or 50%, respectively, of the cutoff concentrations of the drugs. Tests of a panel of 96 compounds yielded only three cases of nonspecific reactivity (at a drug concentration of 100 mg/L). Another panel of 12 compounds that could normally be found in urine samples was also evaluated and no interferences were observed. Concordance was > 95% between this system and the comparable automated immunoassays for detecting drugs of abuse. Greater than 98% of GC/MS-confirmed positive samples gave positive results with this assay system.

Autoanalysis↗