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Biomedical subjects

R Burrows

Publications and source records attributed to R Burrows.

At least 37 records · Page 2Linked to original sources

[Bone mass in celiac patients].

Bone mineral content was measured in the whole body, the spine (L2-L4) and hip by Dual Photonic Absorpciometry (densitometer Norland 2600 Gd-153), in seventeen celiac patients, aged 6 to 12 years, with good adherence to the gluten free diet. The diagnosed was made before 30 months of age in 50% of cases. Average treatment duration was 69.8 +/- 36 months. The randomly selected control group was composed of 48 school age children, of the same age and sex of patients. Total bone mass (TBM) and bone mineral density (BMD) were expressed as Z scores on the basis of normal values established by the authors in Chilean children. Celiac patients had lower TBM and BMD of whole body, than controls (-1.11 +/- 0.94 vs 0.00 +/- 0.85 and -0.59 +/- 0.76 vs 0.06 +/- 0.84, respectively) and at the spine (-0.79 +/- 1.04 vs 0.003 +/- 0.92 and -1.49 +/- 0.99 vs 0.06 +/- 0.87 respectively). A lower TBM was founded at the hip (-0.62 +/- 1.28 vs -0.08 +/- 0.82) without differences in BMD. Celiac patients had a lower bone mass than controls despite early diagnosis and good compliance with the gluten-free diet. These differences could not be atributed entirely to the lower height of celiac patients. These results suggest that celiac patients constitute a risk group for development of osteoporosis later in life. This fact should be taken into consideration in the treatment of this condition.

Bone Density↗

Population dynamics, intervention and survival in African wild dogs (Lycaon pictus).

The demography of Serengeti wild dog study packs and their extinction in 1991 was documented by Burrows et al. (1994). One explanation for pack loss compatible with demographic evidence was viral disease induced by stress caused by intervention (vaccination, immobilization and radio-collaring). Several studies claim to reject this hypothesis. However, cortisol levels measured in immobilized Lycaon, whose pathogen exposure is unknown, do not demonstrate that interventions in the Serengeti were benign. The analysis of survivorship in Lycaon in other ecosystems minimized the chance of demonstrating any effect of intervention and failed to consider vaccinations as intervention. There is now evidence that intervention significantly decreased survivorship of Masai Mara Lycaon. Further simulations of the likelihood of population extinction in Serengeti Lycaon, evidence of limited population variability and a small scaling factor in Serengeti Lycaon strengthen Burrows et al.'s conclusion that the extinction was unlikely to be due to chance alone. Although some studies claim that Lycaon conservation is doomed without intervention, to date vaccinations, blood sampling and radio-telemetry have contributed little to Lycaon conservation. All studies fail to disprove the Burrows hypothesis or provide convincing alternatives.

Animals↗

Traumatised teeth.

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Dental Pulp Necrosis↗

Localization of type XII collagen in normal and healing rabbit cornea by in situ hybridization.

To identify the cell types responsible for type XII collagen synthesis in normal and healing rabbit cornea, a partial cDNA sequence of rabbit type XII collagen, obtained from an adult rabbit cornea cDNA library, was used to develop highly specific oligonucleotide probes for Northern blot analysis and in situ hybridization. Approximately 2000 bases of a type XII collagen 2.2 kb cDNA clone were sequenced. Comparative sequence analysis of the bases showed a 74% identity with chick alpha 1 (XII) chain of type XII collagen. The deduced amino acid sequence indicated a 72% identity with chick type XII collagen. Northern blot analysis showed that cultures of cornea stromal and endothelial cells each contain two RNA species, greater than 10 kb, that hybridize to rabbit type XII collagen oligonucleotide probes. Although normal stromal cells failed to show type XII collagen mRNA, normal endothelial cells contain mRNA for this collagen. These results indicate that endothelium of normal rabbit cornea has a potential to synthesize type XII collagen. During corneal wound healing, both endothelium-derived and stroma-derived cells in the developing scar tissue contained type XII mRNA. In view of the known presence of type XII collagen in corneal stromas from chick and mouse, the distribution of mRNA in normal cornea is puzzling.

Amino Acid Sequence↗

[Psychosocial and familial variables associated with teenage pregnancy].

Preventive measures for teenage pregnancy (TP), would decrease infant mortality, early undernutrition and statal social expenditure. The cost of programs for TP would decrease with a sensitive risk indicator. We searched some pysoshocial and familial parameters, useful to built up this indicator. Self esteem (Piers-Harris test), intrafamilial relationship (Familial Apgar of Magdaleno) and the use of break time were studied in 60 pregnant teenagers (PT), 60 non pregnant teenagers at a low risk of pregnancy (LRP) and 60 non pregnant teenagers at a high risk of pregnancy (HRP). PT and HRP showed lower self esteem than LRP (88.3, 70.0 Y 41.6% respectively, under 7 points) lower familial Apgar (61.6, 50 y 8.3% under score 6) and lower the quality of use of break time (66.7, 74.1 y 31.7% respectively with regular or deficient quality). The self esteem, intrafamilial relationship hand use of break time were associated to early pregnancy and high risk of pregnancy. These parameters are important to built up a sensitive risk indicator of early pregnancy in order to decrease the prevalence of this serious problem.

Adolescent↗

A wolf in wolf's clothing--the abdominal compartment syndrome.

Four patients are described in whom massive abdominal distension after laparotomy led to increased airway and central venous pressure and severely reduced urine output. All cases were associated with massive fluid resuscitation and operative findings were a grossly oedematous bowel with free fluid under pressure in the abdomen. These findings are consistent with the diagnosis of intra-abdominal compartment syndrome. In 1 case trauma was remote from the abdomen indicating that abdominal surgery or trauma may not be a prerequisite for the development of the condition. Recognition of the features of the condition is essential as it can only be treated by decompression of the abdominal contents.

Abdomen↗

Cloning and in situ hybridization of rabbit decorin in corneal tissues.

PURPOSE: To develop molecular probes and to identify the cell types responsible for decorin synthesis in healing cornea. METHODS: Adult rabbit cornea and rabbit corneal stromal cell (keratocyte) culture cDNA libraries were constructed. The libraries were screened with commercially available human cDNA and oligonucleotide probes. Positive clones were sequenced to obtain a full length rabbit decorin cDNA. Synthetic oligonucleotides for rabbit decorin were chosen as probes for Northern blot analysis and in situ hybridization of healing rabbit corneas. RESULTS: The cDNA sequences of the positive clones from the two libraries were identical in areas of overlap. The combined cDNA sequence indicated a 1.5-kb length with a complete open reading frame for decorin. The cDNA and deduced amino acid sequences are 90% and 88% identical, respectively, to previously reported human fibroblast and bovine bone decorin sequences. A hypervariable region near the N-terminal has little homology to decorins of other species or other rabbit protein. Northern blot analysis detected a 2.0-kb and a 2.3-kb band in mRNA from rabbit keratocyte cultures. Decorin mRNA was detected in keratocytes of normal and healing rabbit corneas by in situ hybridization. Label in the healing tissue was markedly increased above normal. Normal endothelium and epithelium in normal and healing cornea failed to show label. CONCLUSIONS: Decorin mRNA from normal adult rabbit cornea is identical to decorin mRNA from keratocytes in culture and is highly homologous to decorin from other animal species. In situ hybridization indicated an upregulation of decorin message in cells adjacent to and within the healing tissue. Both stroma-derived and endothelium-derived cells in the wound synthesize message for decorin.

Amino Acid Sequence↗

[Bone mineralization and calcium intake in Chilean school children].

Bone mineralization was evaluated in 36 school age children with calcium intake below 50% of Recommended Dietary Allowances (RDA), and compared with 28 school age children with calcium intake higher than 100% of the RDA. The total group was aged between 86 and 178 months. The calcium intake was evaluated by 24 hours recordatory survey. Height for age and weight for height were evaluated according to WHO tables. Puberal development was evaluated according to Tanner stages. Bone mineral density (BMD) and total bone mass (TBM) of whole body, spine and femoral neck were measured with Norland 2600 densitometer. School age children with intakes below 50% of RDA had lower height for age adequation (97.7 +/- 4.0%), whole body TBM adequation (98.9 +/- 17.9%) and BMD adequation (97.8 +/- 7.9%) than those ingesting more than 100% of the RDA (115.9 +/- 17.4%), (109.7 +/- 18.0%) and (104.7 +/- 11.1%) respectively. In spine, however, there was a clear tendency to be lower, there were no significant differences between both groups. There were no differences in femoral necks BMD adequation, or TBM adequation between both groups. These results show that children with calcium intake below 50% of the recommendation has lower adequation of statural growth and bone mineralization. The role of calcium in the differences found in this study is discussed.

Adolescent↗

[Bone mineralization in adolescents suffering from postnatal malnutrition].

The bone mineralization of 6 male and 18 female adolescents with a mean age of 12 years and 11 months, who had suffered severe, early, postnatal protein-energy undernutrition, was analyzed. These patients have been followed up at our Institute since their nutritional rehabilitation. Bone mineralization was measured by bone dual isotopic densitometry (Gd 153). These results were compared with those of normal school-age Chilean children of the same age and sex. Weight for height of adolescent who had suffered from undernutrition was similar to the controls, and both were over 100% of the standard. Adequation of height for age was significantly less in those with previous history of undernutrition. Densitometries showed that adolescents with a past history of undernutrition had lower total bone mass in whole body, spine and femoral neck; differences disappeared when expressed per 100 cm of body height. There were no differences in bone mineral density in the different area measurements. It is concluded that the possible alterations that undernutrition produces in bone mineralization probably recover after nutritional rehabilitation, adequate nutritional follow up and health support.

Calcification, Physiologic↗

Demography, extinction and intervention in a small population: the case of the Serengeti wild dogs.

The effects of ecological factors (prey, competitors, predators and disease) and intervention (immobilization, radio-collaring, and vaccination) on population size and demography were investigated in Serengeti wild dogs (Lycaon pictus), an endangered canid, between 1965 and 1991. Variation in ecological factors explained most changes in demography, but did not explain a decline in adult longevity. A significant reduction in pack life and individual longevity was coincident with the introduction of routine intervention and consistent with pathogen-induced mortality. Survival varied significantly between categories of intervention, and between individuals likely to have been exposed to different degrees of social stress before intervention. The loss of all study packs in 1991 contrasted with the persistence of breeding packs outside the study area. The cause of the demise of most study packs is unknown. Monte Carlo simulations demonstrated that population extinction was unlikely to be the consequence of chance events alone. One explanation compatible with the evidence is an outbreak of viral disease induced by stress, possibly caused by intervention.

Animals↗

[Early pregnancy risk: development and validation of a predictive instrument].

An early pregnancy risk scale, with scores ranging from 11 to 66 points from lower to higher risk, was constructed using variables associated with teenager's pregnancy. This scale was applied to 3000 female teenagers, coming from Metropolitan Santiago public schools. The sample was divided in three risk groups: group A (high risk) with scores equal or over 35 points, group B (low risk) with scores equal or below 20 points and group B (intermediate risk) with scores between 20.1 and 34.9 points. These girls were followed during 2 years. During this period, 84 girls became pregnant, 24 of 184 (13%) in group A, 60 of 2332 (2.6%) in group C and none of 307 in group B. There were 104 school desertions in group A and 37 in group B. To study associations and analyze risk, the sample was divided in two risk groups: high, with scores over 27 and low, with scores below 27. There was a high association between pregnancy risk score and the occurrence of pregnancy (RR 5.25 p < 0.0001) and school desertion (RR 3.32 p < 0.0001). Pregnancy was predicted with a 78% sensitivity and 55.6% specificity. School desertion was predicted with a 74% sensitivity and 56% specificity. The importance variable weighing using multiple regression models, to improve the predictor's sensitivity and specificity, is discussed.

Adolescent↗

[Bone mineralization in Chilean children determined by dual photon bone densitometry].

In 198 school age children, aged 6 to 13 years, the bone mineral density (BMD) and total bone mass (TBM) was measured in total body, lumbar spine and hip, using a double beam photon densitometer with a Gd 153 source. An increase with age of BMD and TBM was found in all the analyzed areas. At 12 years of age, TBM and BMD of total body were higher in girls than in boys. BMD of lumbar spine was significantly higher in girls than in boys at ages between 11 to 13 years. BMD of lumbar spine and femoral neck of 9 years old females were 36% and 18% respectively, lower than values of young adult Chilean females. The importance of normal values of bone mineralization for the diagnosis of bone diseases and for the evaluation of programmes directed to solve this problems is emphasized.

Absorptiometry, Photon↗