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Biomedical subjects

R Cruz

Publications and source records attributed to R Cruz.

At least 55 records · Page 3Linked to original sources
PubMed1995

Hematologic safety of intraosseous blood transfusion in a swine model of pediatric hemorrhagic hypovolemia.

OBJECTIVE: To assess the risk of hemolysis, disseminated intravascular coagulation (DIC), or fat embolism syndrome (FES) with pressurized intraosseous (IO) blood transfusion following hemorrhage. METHODS: A controlled, repeated-measures, randomized animal study with blinded pathologic evaluations was conducted. Sixteen pentobarbital-anesthetized, instrumented immature swine underwent a 20-mL/kg hemorrhage into citrate-phosphate-dextrose bags, then received autologous blood transfusion via a 16-ga i.v. catheter (eight), or via a 15-ga IO needle in the proximal tibia (eight) under maximal manual pressure using a 30-mL syringe. At baseline and at one hour and 48 hours posttransfusion, blood samples were assayed for hemoglobin (Hb), schistocytes, free Hb in plasma, bilirubin, lactate dehydrogenase, platelets, fibrinogen, and alveolar-arteriolar O2 gradient. Lung sections were examined for inflammation after hematoxylin/eosin stain, and for fat emboli after oil red-O-stain. Kidney sections were examined for inflammation using hematoxylin/eosin stain. RESULTS: Though the IO transfusion rate of 21 +/- 6 mL/min was slower than the i.v. rate of 35 +/- 5 mL/min (p = 0.0012), all the animals returned to baseline blood pressure within 15 minutes and survived. The presence of schistocytes and mildly elevated free Hb in plasma was noted in both groups at baseline and each time period, and was presumed to be due to sampling from the arterial catheter. All other laboratory values remained within normal limits and without intergroup differences at any time period. No fat embolus was noted, and all lung and kidney specimens were free of inflammation. CONCLUSIONS: In this model, pressurized IO blood transfusion appears to be hematologically safe, i.e., without risk of appreciable hemolysis, DIC, or FES.

Animals↗
PubMed1995

[Age and racial geographic distribution of S hemoglobin in Brazil].

OBJECTIVES: This paper was meant to analyse distribution of HbS carriers in Brazil, comprising its regional prevalence and the relationship with racial settlement and age groups. MATERIAL AND METHODS: 67,667 blood samples from 48 Brazilian towns were analysed from 1976 to 1988. Such samples were classified as Caucasoid and Negroid. The diagnosis was defined by means of qualitative electrophoresis in alkaline and acid pH, quantification of haemoglobin fractions, cytological studies and some cases were confirmed after examination of the parents. RESULTS: The study of those 67,667 samples allowed us to detect 1,492 HbS carriers (2.2%). That frequency is higher among Negroids (5.16%) than among Caucasoids (1.22%): Z = 22.1397 (Zcritical; 0.05 = 1.9600). Taking the HbS carrier distribution into consideration, we noticed that it is relatively homogeneous among Negroids and higher than 5% in 9 out of the 16 areas involved in the study. By classifying the age group of the areas in the general sample and by comparing the proportions, we found out that there are significant differences (chi 2 = 50.88; chi 2 critical; 0.05; 5 gl = 11.070). CONCLUSIONS: Sickle-cell anaemia diseases play an important role among the pathologies found in several countries, including Brazil. This paper shows that the carriers prevalence varies in the several areas under study and is higher among Negroids in almost all of them. The decreasing frequency occurring from North to South in the general samples and among Caucasoids may be assigned to the contribution of the Negroes in the interracial crossing, particularly in the Northeast.

Age Distribution↗
PubMed1994

Alkali-soluble fluoride deposition on human enamel exposed to monofluorophosphate-containing toothpastes in vitro.

Enamel specimens from unerupted third molars were treated with the supernatant of monofluorophosphate (MFP)-containing toothpaste slurries in water. Calcium fluoride-like particles were formed on the enamel surface during a 24-h exposure. The globules were soluble in alkali. More particles were seen on enamel treated with a toothpaste containing both MFP and NaF. The experiments showed that the calcium fluoride-like material formed on enamel after treatment with MFP-containing toothpaste probably originates from the free fluoride present in the pastes. The relatively moderate deposition of fluoride may be of clinical significance because the teeth are so frequently exposed to toothpaste. No firmly bound fluoride was found on treatment of enamel with MFP-containing toothpaste.

Adsorption↗
PubMed1993

Dietary selenium affects methylation of the wobble nucleoside in the anticodon of selenocysteine tRNA([Ser]Sec).

We reported previously that the presence of selenium in culture media of mammalian cells influences both the steady-state levels and distributions of two tRNA isoacceptors involved in the insertion of selenocysteine into protein in response to certain UGA codons. In this study, we demonstrate an increase in the levels of these isoacceptors in rats fed a selenium-adequate diet compared to animals fed a selenium-deficient diet, as well as a shift in the relative distribution toward the tRNA which elutes later from an RPC-5 column. These effects were found to occur in a tissue-specific manner. Both selenocysteine tRNAs were isolated from rat liver, sequenced, analyzed by mass spectrometry, and shown to differ only by ribose 2'-O-methylation of 5-methylcarboxymethyluridine that occurs in the wobble position of the anticodon. This modified nucleoside has been documented previously only in yeast tRNA while the corresponding 2'-O-methylribose derivative has not been observed. The structure of these nucleosides was established by mass spectrometry and confirmed by chemical synthesis. Although the role of methylation of the wobble nucleotide is not known, the differences in elution properties from RPC-5 columns are consistent with other experimental observations indicating that a change in tRNA conformation accompanies this methylation.

Animals↗
PubMed1993

Fluoride acquisition on and in fluorotic human enamel after topical application in vitro.

The uptake of alkali soluble and alkali insoluble fluoride on and in fluorotic enamel was investigated in vitro. Teeth from Kenya, assigned score 3 in accordance with Thylstrup-Fejerskov's fluorosis index, were used. The enamel was treated with either a neutral 2% NaF solution, a 0.2% NaF solution (pH 5.5), or the supernatant from a 0.1% NaF-containing toothpaste (pH 7). The treatment time was 1 h. The reaction product formed on the enamel was analyzed by KOH extraction and acid etching. Significantly higher amounts of alkali soluble fluoride were formed on the enamel from the 2% and 0.2% NaF solutions, as compared with the control. There was also a significant increase in the firmly bound fluoride after treatment with the neutral 2% NaF solution.

Analysis of Variance↗
PubMed1992

A pseudogene for human glutathione peroxidase.

Glutathione peroxidases (GPx) serve a bioprotective function in the reduction of peroxides to less toxic substances. Both cellular and secreted forms of the protein have been reported, as well a number of distinct cDNA sequences. Previous efforts have described three distinct loci on human chromosomes 3, 21 and X which hybridize to a GPX cDNA and these authors have speculated that only the chromosome 3 locus encodes a functional GPX gene. This conclusion was based on mapping studies showing a precise deletion of intron sequences in the GPX loci on chromosomes 21 and X despite strong conservation among these sequences in both the coding and 3'-untranslated regions. To pursue this issue, we have isolated the chromosome 21 GPX locus by molecular cloning and determined its nucleotide sequence. Consistent with the expectations of McBride et al. [Biofactors 4 (1988) 285-292], the sequence does reveal a highly conserved processed pseudogene. It is suggested that a retrotransposed copy of the GPX gene integrated into chromosome 21 and may have maintained activity prior to the accumulation of inactivating mutations.

Base Sequence↗
PubMed1992

Tensile strength of orthodontic brackets bonded directly to fluorotic and nonfluorotic teeth: an in vitro comparative study.

Information related to bonding of orthodontic brackets to fluorotic teeth is scanty. The purpose of this study was to compare, in vitro, the tensile bond strength and the bond failure site of brackets bonded directly to fluorotic and nonfluorotic teeth. The etching patterns were also evaluated. The study involved 26 teeth classified as score 3 and 4, and 26 as score 0 with the Thylstrup and Fejerskov's (TF) fluorosis index. In addition to the clinical classification, difference in the concentration of fluoride in the teeth was verified by acid etching. Brackets were bonded with a composite resin after etching the enamel surface with 40% phosphoric acid for 60 seconds. Tensile bond strength was determined with an Instron testing machine. The bond failure site was assessed by the percentage of residue cement on the tooth surface after debonding and the etching pattern by SEM. The mean concentration of fluoride was 2888.5 ppm (SD 1081.7) in the fluorotic teeth and 1227.1 ppm (SD 526.3) in the nonfluorotic teeth. The mean bond strength was 7.8 N/mm2 (SD 1.47) for the fluorotic teeth and 8.6 N/mm2 (SD 2.19) for the nonfluorotic teeth. The difference between the means for bond strength was not statistically significant (p greater than 0.05). Bond failure site was primarily at the bracket-adhesive interface. The mean percentage of adhesive on the enamel surface after debonding was 70% (SD 25.90) for the fluorotic teeth and 75% (SD 24.66) for nonfluorotic teeth. The difference in the means was not statistically significant (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗
PubMed1992

More about the multiplicative model for the analysis of genotype-environment interaction.

In this paper various multiplicative models that are often used to analyse genotype-environment interaction are described and some of the statistical relationships between them are explored. It is shown that principal-component analysis can be seen as a natural generalization of the joint regression analysis. A set of maize data is used to exemplify these statistical models.

Environment↗
PubMed1992

Clomipramine side effects.

Explore the source record for details and available documents.

Attention Deficit Disorder with Hyperactivity↗
PubMed1992

Acquisition of alkali-soluble fluoride by enamel through treatment with NaF-containing toothpastes in vitro.

The first aim of the present study was to examine if alkali-soluble fluoride (calcium fluoride-like material and adsorbed fluoride) forms when a NaF-containing toothpaste is applied on human enamel surface in vitro. The centrifuged supernatants of toothpastes dissolved in distilled water were used and four different commercial NaF-containing toothpastes were tested. The second aim was to investigate if pyrophosphate would interfere with the deposition of alkali soluble fluoride. The formation of alkali-soluble fluoride was determined by chemical analysis and visualized by scanning electron microscopy (SEM). It was ascertained that all tested toothpastes contained free fluoride according to the manufacturers' specifications. It was shown that they promoted deposition of alkali soluble fluoride on the enamel surface. The amount of deposited material increased with the time of exposure. The clinical effect of a NaF-containing toothpaste may thus well depend on an initial formation of alkali-soluble fluoride. Fluoride from this reservoir may adsorb onto the enamel crystals and inhibit further demineralization or increase the rate of remineralization during cariogenic challenges. It was also demonstrated that pyrophosphate did not interfere with the deposition of alkali soluble fluoride.

Adsorption↗
PubMed1992

Uptake of KOH-soluble and KOH-insoluble fluoride in sound human enamel after topical application of a fluoride varnish (Duraphat) or a neutral 2% NaF solution in vitro.

The uptake of alkali-soluble fluoride (calcium fluoride-like material and adsorbed fluoride) and alkali-insoluble fluoride (apatitically bound fluoride) on sound human enamel from treatment with Duraphat or a neutral 2% NaF solution was investigated in vitro. Blocks from impacted third molars were used. More fluoride was deposited on the enamel from the neutral 2% NaF solution than from the Duraphat treatment. All the fluoride could be dissolved in alkali. Globules of calcium fluoride-like material were demonstrated by scanning electron microscopy. Chemical analysis showed no measurable increase in the apatitically bound fluoride (alkali-insoluble fluoride) after brief exposures. Duraphat-treated samples submerged in water after the exposure lost only about 50% of the deposited fluoride, whereas samples treated with 2% NaF are known to lose all their fluoride under similar circumstances, a condition which may be related to the favorable clinical effect of Duraphat.

Acid Etching, Dental↗
PubMed1992

The effect of time of exposure on fluoride uptake by human enamel from acidulated fluoride solutions in vitro.

Fluoride uptake on and in enamel during topical application of acidulated solutions was studied. The variables were different time intervals and different pH levels of the treatment solutions. The experiment was carried out with human enamel exposed to 2% NaF solutions, pH 3.5 and 5.5, for 30 sec, 60 sec, 5 min, and 60 min. The amounts of fluoride formed on (as calcium fluoride) and in (as fluorapatite) enamel were determined by chemical assessments, and scanning electron microscopy provided the visualization of the deposits on the surface. It could be demonstrated that the two pH levels caused deposition of large amounts of calcium fluoride and that almost twice as much was deposited at pH 3.5 as at 5.5. The amount of deposit increased rapidly with time of exposure in both situations compared with similar experiments with neutral fluoride solutions. Firmly bound fluoride was incorporated in the enamel only during the 60-min incubation.

Calcium Fluoride↗
PubMed1991

DNase activity in Costa Rican crotaline snake venoms: quantification of activity and identification of electrophoretic variants.

DNase activity of Costa Rican crotaline snake venoms from the genera Bothrops, Crotalus and Lachesis was quantified by an enzymodiffusion method on agarose/DNA gels containing ethidium bromide. The reaction is detected as a ring lacking fluorescence when gels are visualized under u.v. light. Electrophoresis of non-fluorescent areas demonstrated DNA degradation. All of the venoms had DNase activity, B. schlegelii being most active. Venoms from B. schlegelii and B. asper induced an inner hyper-fluorescent ring in addition to the external non-fluorescent ring, probably caused by the formation of complexes between DNA and highly basic proteins present in these venoms. In order to study the number of electrophoretic DNase variants, venoms were separated by analytical isoelectric focusing on polyacrylamide minigels, proteins were transferred to nitrocellulose paper and the paper was placed over an agarose gel containing DNA. Then the agarose gel was stained with ethidium bromide and the bands of DNase activity were visualized under u.v. light. All the venoms tested, as well as commercial DNase showed several bands with DNase activity. The majority of venom DNase variants have basic pIs although bands with acidic pIs were also present in B. godmani and L. muta venoms. No major differences in the DNase electrophoretic pattern were observed between individual venoms of adult B. asper specimens nor between lyophilized and frozen venoms.

Crotalid Venoms↗
PubMed1991

Deposition of alkali-soluble fluoride on enamel surface with or without pellicle.

Deposition of alkali-soluble fluoride on enamel in the presence and absence of an acquired pellicle was studied in vitro during a single topical application of a 2% sodium fluoride solution at neutral pH. Five experimental groups of repeated measures design were established. The amount of alkali-soluble fluoride formed on enamel (i.e., calcium fluoride) was measured by chemical assessments and by SEM. The results showed that there were no differences among the groups demonstrating the incapacity of pellicle to interfere with deposition of alkali-soluble fluoride on enamel. The fluoride ions are thus able to reach the enamel in spite of the presence of the pellicle.

Alkalies↗
PubMed1991

Formation of fluoride on enamel in vitro after exposure to fluoridated mouthrinses.

The aim of this study was to quantify the formation of alkali-soluble fluoride (loosely bound fluoride such as calcium fluoride-like material and absorbed fluoride) and alkali-insoluble fluoride (firmly bound fluoride or apatitically bound fluoride) when fluoride mouthrinsing solutions were applied on sound human enamel in vitro. Two commercial products containing 0.2% or 0.05% NaF were used during 30 sec, 60 sec, 5 min, and 60 min. The formation of loosely bound fluoride was determined by KOH extraction and visualized by scanning electron microscopy. The firmly bound fluoride was measured by three consecutive acid etchings of the enamel. Even during short periods of application there were deposits on the enamel surface. The amount of deposit increased with time of exposure to the 0.2% NaF solution. Only after treatment for 60 min with 0.05% NaF were significant amounts of alkali-soluble fluoride deposited. No measurable amounts of firmly bound fluoride were observed.

Calcium Fluoride↗
PubMed1988

Para-oesophageal synovial sarcoma.

An unusual case of mediastinal synovial sarcoma with secondary invasion of the oesophagus simulating an intra-oesophageal mass is reported. The location and radiological appearance of this tumour are exceptional, and, to the authors' knowledge, have not been reported previously.

Adult↗
PubMed1982

The relationship among the permeability to iodide, pore volume, and intraoral mineralization of abraded enamel.

The results indicate that Ip measurements are fairly closely related to the pore volume of the enamel to a depth of about 13 micrometer. A previous finding - that intraoral exposure produced substantial mineralization of abraded enamel after one h, and a slower rate of mineralization during the next two h - was confirmed, and it was shown that the rate of mineralization decreased with a decrease in the pore volume of the enamel. The rapid rate of intraoral mineralization represents a powerful mechanism for maintaining a fully mineralized enamel surface. The sensitivity of the Ip method demonstrated in this study, and the finding that Ip measurements relate to the pore volume of the enamel, coupled with previous findings that the increase in Ip produced by mild acid etching of intact enamel is proportional with the amount of dissolved Ca, indicate that the method provides valid measurement of intraoral de- and remineralization.

Acid Etching, Dental↗