PubMed Health⌕ Search

Biomedical subjects

V Santos

Publications and source records attributed to V Santos.

30 records · Page 2Linked to original sources
PubMed1991

Parental reports of apnea and bradycardia: temporal characteristics and accuracy.

A prospective examination was made of the temporal course of parental observations in response to a monitor alarm of apnea (apnea setting of 20 seconds) or bradycardia (bradycardia setting of 80 beats per minute). Data were obtained from 155 subsequent sudden infant death syndrome siblings followed up at home, during the first 20 weeks of life, on an apnea/bradycardia monitor with an attached event recorder. In addition, parental reports were compared to an objective recording of the pattern of cardiorespiratory activity surrounding each monitor alarm. Only those parental observations were considered which reported the infant to be asleep with no apparent equipment malfunction following an apnea alarm (with or without pallor, cyanosis, or the provision of external stimulation) or a low heart rate alarm associated with pallor, cyanosis, or stimulation. Observations were analyzed within each of five age periods (less than 29, 29 through 56, 57 through 84, 85 through 112, 113 through 140 days). The percentage of infants reported to have prolonged apnea, prolonged apnea with stimulation, or bradycardia with stimulation was found to decrease with age. An examination of the linked event recordings failed to document an episode of apnea as long as 15 seconds for any of the reported episodes of apnea. Furthermore, bradycardia as long as 5 seconds in duration could be documented in only 3 of 422 reported episodes of bradycardia. These results indicate the potential for considerable error when total reliance is placed on parental observations and point to the necessity for objective event recordings when using home monitors in the clinical management of at-risk infants.

Apnea↗
PubMed1990

Melanosis of the larynx.

A case of laryngeal melanosis is presented. This is followed by the analysis of the total of nine cases reported in the English literature. Patients are men in their sixth to eighth decade of life who present with hoarseness. Histopathologic findings include pigment deposits in the basal layer of the laryngeal epithelium. The possible relation of this lesion to carcinoma of the larynx is discussed.

Humans↗
PubMed1989

Human and mouse cementum proteins immunologically related to enamel proteins.

SDS-polyacrylamide gel electrophoresis, immunoblot and amino acid composition analyses were applied to human and mouse acellular cementum proteins immunologically related to enamelins and amelogenins. In this analysis, anti-mouse amelogenin, anti-human enamelin and synthetic peptide (e.g., -LPPHPGHPGYIC-) antibodies were shown to cross-react with tooth crown-derived enamelin with a molecular mass of 72,000 Da (72 kDa), amelogenins (26 kDa), and also to four human cementum proteins (72, 58, 50 and 26 kDa) and two mouse cementum proteins (72 and 26 kDa). Each of the antibodies recognized tooth root-derived cementum polypeptides which share one or more epitopes with tooth crown-derived enamel proteins. The molecular mass and isoelectric points for crown-derived and root-derived enamel-related proteins were similar. Analysis of human and mouse cementum proteins revealed a characteristic amino acid composition enriched in glutamyl, serine, glycine, alanine, proline, valine and leucine residues; compared to the major enamel protein amelogenin, cementum proteins were low in proline, histidine and methionine. The human and mouse putative intermediate cementum proteins appear to represent a distinct class of enamel-related proteins. Moreover, these results support the hypothesis that epithelial root sheath epithelia express several cementum proteins immunologically related to canonical enamel proteins.

Amelogenin↗
PubMed1989

Hertwig's epithelial root sheath differentiation and initial cementum and bone formation during long-term organ culture of mouse mandibular first molars using serumless, chemically-defined medium.

Studies were designed to test the hypothesis that Hertwig's epithelial root sheath (HERS) synthesizes and secretes enamel-related proteins that participate in the process of acellular cementum formation. Our experimental strategy was to examine sequential root development of the mouse mandibular first molar in vivo and in long-term organ culture in vitro using serumless, chemically-defined medium. Using anti-amelogenin, anti-enamelin and anti-peptide antibodies, enamel-related antigens were localized within intermediate cementum during HERS differentiation and root formation in vivo. Cap stage molars maintained for periods of up to 31 days in organ culture expressed morphogenesis and cytodifferentiation as identified by tooth crown and initial root, cementum and bone formation. Metabolically-labeled HERS products were analyzed by immunodetection using enamel-related antibodies and one- and two-dimensional SDS gel electrophoresis. A 72 kDa and 26 kDa polypeptide were identified in forming mouse cementum. Both of these root putative cementum proteins yield similar (identical) amino acid compositions; however, both proteins differed from the compositions of either mouse crown enamelin or amelogenin proteins. This approach provides a new and novel in vitro model towards understanding HERS differentiation and functions related to root and bone formation. The data support the hypothesis that HERS cells synthesize polypeptides related to but also different from canonical crown enamel proteins.

Animals↗
PubMed1988

Metabolic expression of intrinsic developmental programs for dentine and enamel biomineralization in serumless, chemically-defined, organotypic culture.

Biomineralization was investigated using embryonic mouse mandibular first molars (M1) cultured in the presence or absence of fetal calf serum. Metabolic features including cell division and Ca2+ and phosphate incorporation into dentine and enamel extracellular matrices were analyzed. The relative timing and magnitude of DNA synthesis for serumless cultures was comparable to in vivo controls. Isotopic calcium and phosphate incorporation into the mineral phase of dentine and enamel matrices, in the absence of serum, fluctuated during development. Molar tooth morphogenesis, cytodifferentiation, and extracellular matrix formation approximated late crown-stage development in serumless cultures. Von Kossa histochemical staining indicated calcium phosphate salt formation in serumless cultures. Analysis of anhydrous fixation-prepared enamel and dentine representing serumless cultured explants indicated that crystal size and orientation were comparable to in vivo enamel and dentine. In contrast, serum-supplemented cultures showed atypical crystal size and orientation. Calcium/phosphorous (Ca/P) ratio values for serumless cultures after 21 days showed Ca/P enamel values of 2.03 (SD +/- 0.04, p less than 0.025) and dentine values of 1.89 (SD +/- 0.01, p less than 0.025). Electron diffraction patterns of enamel and dentine formed in serumless cultures were principally those of highly-ordered crystalline hydroxyapatite. Our results suggest that tissue-specific dentine and enamel biomineralization is regulated by endogenous factors intrinsic to the developmental program of embryonic tooth organs during serumless culture.

Animals↗
PubMed1983

Selachian tooth development: II. Immunolocalization of amelogenin polypeptides in epithelium during secretory amelogenesis in Squalus acanthias.

We have determined the distribution of amelogenin polypeptides in an order of elasmobranchs using indirect immunofluorescence with rabbit polyclonal antibodies prepared to purified murine amelogenins. We find that amelogenins are definitely present within the inner enamel epithelium prior to the production of the extracellular matrix component termed "enameloid" (row II developing tooth organs). During subsequent stages of selachian tooth development (row III tooth organs), immunofluorescence staining data indicated localization of amelogenin antigens within epithelium as well as the enameloid extracellular matrix. The results from these immunohistochemical studies suggest that the 16-20 kdalton amelogenins, which are characteristic of murine inner enamel epithelial cells undergoing terminal biochemical differentiation into secretory ameloblasts, may also be regarded as molecular markers for amelogenesis in developing teeth in the spiny dogfish, Squalus acanthias.

Amelogenesis↗
PubMed1983

Selachian tooth development: I. Histogenesis, morphogenesis, and anatomical features in Squalus acanthias.

We have determined the general features of epithelial-mesenchymal interactions during fetal and mature adult stages of odontogenesis in the selachian spiny dogfish, Squalus acanthias. The general features of odontogenesis included the formation of an extended dental lamina, bud, cap, bell, and crown stages as identified and described using serial sections from fetal as well as adult specimens and light microscopy. Fetal and adult lengths, the rostrum-caudal fin distance, were correlated with the number of tooth rows and columns present in each specimen. This positional information and terminology was extremely valuable in attempting to acquire reproducible data for analyses. Whereas a number of histologic features of fetal and adult odontogenesis were comparable to those described in Mammalia, we found a number of epithelial-mesenchymal interaction characteristics unique to elasmobranch tooth development, including the persistence of the dental lamina in the adult stages, the coupling of cervical inner enamel epithelia between sequential stages of tooth formation, and the patterns of odontogenesis in the adult dentition.

Animals↗
PubMedDate not supplied

Whole blood glutathione peroxidase and erythrocyte superoxide dismutase activities, serum trace elements (Se, Cu, Zn) and cardiovascular risk factors in subjects from the city of Ponta Delgada, Island of San Miguel, The Azores Archipelago, Portugal.

Activities of whole blood glutathione peroxidase (GSH-Px) and erythrocyte superoxide dismutase (SOD) and serum levels of selenium (Se), copper (Cu) and zinc (Zn) were measured in 118 apparently healthy subjects aged 20-60 years from the city of Ponta Delgada, Island of San Miguel, The Azores Archipelago, Portugal. Data were analysed by age/gender, lipid profile and blood pressure as cardiovascular risk factors searching for their relevance when assessing reference values for antioxidant biomarkers. GSH-Px was in the same range, but SOD was significantly lower than in other Portuguese populations. Neither activity differed with gender. GSH-Px activity increased with age, namely in normolipidemic men versus the hyperlipidemic group in which a decrease was observed. This suggests a progressive impairment of GSH-Px with age caused by an enhanced production of oxidant species in hyperlipidemia. GSH-Px was 30% lower in male hypertensives versus normotensives. SOD activity did not relate to age or blood pressure but was 17% higher in the hyperlipidemic men versus the normolipidemic group, suggesting a better antioxidant protection by SOD than by GSH-Px in hyperlipidemia and hypertension. Se was higher in men versus women, particularly in the older subjects, and partly related to hyperlipidemia. Zn levels showed a similar dependency on gender, not related to age or lipid profile. Cu levels were much higher in women than in men in all age or lipid profile classes and decreased in hyperlipidemia. They were lowered with age in both genders, particularly in normolipidemic women. The present research therefore suggests that hyperlipidemia and hypertension do affect antioxidant status and should be considered when assessing antioxidant biomarkers in blood.

Adult↗