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Biomedical subjects

J Osborn

Publications and source records attributed to J Osborn.

At least 55 records · Page 3Linked to original sources
PubMed1990

Comparison of measurement variability using a standard and constant force periodontal probe.

This study compared the intra- and inter-examiner reliability of the Florida Probe, Florida Disk Probe, and conventional periodontal probe. Using these instruments, each of three examiners made repeated measurements of probing depth (using the Florida Probe and conventional probe), relative attachment level (using the Florida Disk Probe), and clinical attachment level (using a conventional probe) at posterior, proximal sites in 10 subjects with early periodontitis. The mean intra-examiner standard deviation of differences in repeated probing depth measurements ranged from 0.46 to 0.77 mm demonstrating similar levels of reproducibility between the Florida Probe and conventional probe. The mean intra-examiner standard deviation of differences in repeated relative attachment level measurements using the Florida Disk Probe ranged from 0.44 to 0.57 mm using double passes and from 0.98 to 1.41 mm using single passes of measurements. For clinical attachment level measurements obtained using single passes of measurements with a conventional probe, the mean intra-examiner standard deviation of differences ranged from 0.78 to 0.95 mm. Inter-examiner variability was generally greater than intra-examiner variability for all instruments. It was concluded that double passes with the Florida Disk Probe offers significant advantages for measuring relative attachment level in longitudinal studies of early periodontitis when decisions for change must be made as soon as possible.

Bias↗
PubMed1990

Endoscopy in dyspeptic patients: is gastric mucosal biopsy useful?

Should dyspeptic patients coming to endoscopy with "normal" findings also be biopsied? To assess this, we studied the sensitivity and specificity of endoscopic examination compared with histology, microscopic evidence of Helicobacter pylori, CP-TEST, culture, and serum IgG and IgA antibody titers to H. pylori to determine whether endoscopy and antral biopsies really are useful. One hundred seven consecutive dyspeptic patients (mean age 43 yr) were entered. Four antral biopsies were taken routinely for evaluation by histology, microscopy, CP-TEST, and culture. Serum IgG and IgA antibody levels were measured in all patients. Of symptoms, postprandial bloating was statistically more common in H. pylori-positive than in negative patients. Endoscopy had the poorest sensitivity (37.1%) and specificity (53.3%). Patients with normal endoscopic appearances but histologically confirmed gastritis had significantly higher IgG and IgA titers than the patients normal by both endoscopy and histology and without evidence of H. pylori. This study has shown that endoscopy is unhelpful in dyspeptic patients if endoscopic biopsies are not routinely taken.

Adult↗
PubMed1989

[Aspects of distribution of plasma cells at the advancing front of the lesion in chronic periodontitis: a quantitative ultrastructural study].

The aim of this study was to compare the distribution of plasma cells within the soft tissue walls of interdental deep pockets from patients with adult (AP) and juvenile/post-juvenile (JP/PJP) periodontitis. Biopsies from 20 patients and 3 control volunteers were examined: 5 with treated AP, 5 with untreated AP, 5 with treated JP/PJP and 5 with untreated JP/PJP. No plasma cells were seen within the epithelium from any of the biopsies examined, and they were very sparse within the connective tissue from the control specimens. In all the pathological specimens examined there was marked tissue destruction. The percentage density of plasma cells tended to be statistically significantly higher in JP/PJP than in AP, and in untreated than in treated lesions. The statistical analysis showed also that plasma cells were more abundant in a layer deep to the neutrophils lining the basement membrane. Plasma cells were also more abundant in areas of extensive histological inflammation. The plasma cells were often degenerate and such degeneration appeared more evident in JP/PJP and in areas of connective tissue devoid of vascular tissue. These findings appear to indicate an association between increase of collagen destruction and increase in plasma cell percentage density. This may relate in turn to an increase in penetration and/or virulence of components of the subgingival plaque following an increase in tissue permeability. The scarcity of Russell bodies within the plasma cells would suggest that immunoglobulin production and secretion are normal.

Adult↗
PubMed1984

Influence of vasopressin and angiotensin on baroreflexes in the dog.

Cardiovascular responses to step-changes of carotid sinus pressure were evaluated at normal and elevated levels of plasma arginine vasopressin in anesthetized neurohypophysectomized dogs (n = 12). Arginine vasopressin influenced autonomic function in two ways: first, maximum carotid reflex gain increased; second, cardiac output was decreased. The enhancement of reflex strength was observed only in response to decreases of intrasinus pressure below the equilibrium point (pressures of between 60 and 105 mm Hg). Aortic pressure rose twice as high for a given decrease of intrasinus pressure, elevations of total peripheral resistance responses were triple those observed at normal plasma arginine vasopressin. In this way, arginine vasopressin more than doubled the ability of the carotid reflexes to return a drop in arterial pressure to normal. Arginine vasopressin enhancement of reflex gain was not observed with elevations of intrasinus pressures above the equilibrium point. Elevation of aortic pressure expected from the vasoconstrictor actions of infused arginine vasopressin were buffered by associated reductions in cardiac output. Vagally mediated bradycardia was consistently observed with elevated arginine vasopressin, but the reflex response of heart rate to step-changes of intrasinus pressure was unchanged. Time control studies in five neurohypophysectomized dogs indicated no significant change in carotid reflex response over the 3- to 4-hour protocol. Comparison of reflex responses in anephric dogs (n = 8) at low and elevated levels of angiotensin II indicated that this vasoactive peptide did not significantly alter reflex responsiveness. We conclude that arginine vasopressin enhances the ability of the carotid reflexes to normalize decreases of arterial pressure, but buffers a rise in pressure from its own vasoactive properties by initiating a fall of cardiac output.

Angiotensin II↗
PubMed1981

Continuous blood pressure measurement in rats with aortic baroreceptor deafferentation.

The purpose of this study was to determine if once-daily arterial pressure measurements are a reliable estimate of actual time-averaged arterial pressure in neurogenic hypertensive rats. Male rats were subjected to either aortic baroreceptor deafferentation (ABD, n = 10) or sham operation (SO, n = 10). One to 3 mo later, arterial pressure (AP) was recorded from a chronic indwelling catheter in each rat for 72 continuous hours. Subsequently, AP was determined once a day (10- to 30-min recording periods) in each rat for an additional 3 consecutive days. Continuous recording yielded an average mean arterial pressure (MAP) of 104 +/- 2 mmHg in SO rats and an average mean MAP of 120 +/- 3 mmHg in ABD rats. Standard deviation of MAP measured every 5 min for 24 consecutive hours (as an index of pressure lability) was 8.0 +/- 0.4 mmHg in SO rats and 14.4 +/- 1.3 mmHg in ABD rats. Both of the above differences were statistically significant (P less than 0.05). The average MAP from daily measurements in the same rats was 107 +/- 3 mmHg in SO rats and 124 +/- 3 mmHg in ABD rats. Average pressure values were not statistically different for the two measurement techniques in either group of rats. Overall, there existed a significant correlation (r = 0.64, P less than 0.01) between MAP measured continuously and daily in the 20 rats studied. We conclude that daily direct measurement of MAP in conscious ABD rats yields a satisfactory estimate of actual time-averaged MAP in these rats despite their markedly increased MAP lability.

Afferent Pathways↗
PubMedDate not supplied

Residual insulin secretion at diagnosis of type 1 diabetes is independently associated with both, age of onset and HLA genotype.

BACKGROUND: We investigated whether residual insulin secretion and metabolic derangement at diagnosis of type 1 diabetes (T1DM) are influenced by human leukocyte antigens (HLA) class II genes. METHODS: Eight hundred and seventy-one T1DM consecutive Caucasian patients were typed for HLA class II genes. In 300 of these patients, glycated haemoglobin, insulin requirement, baseline C-peptide and body mass index (BMI) Z-score were measured at clinical diagnosis. The effect of the HLA genotypes on the quantitative variables was investigated using multiple linear regression. The beta coefficient regression of the age at onset and HLA genotypes were standardized to compare their specific importance for C-peptide levels. RESULTS: The HLA genotypes were divided in high-, moderate- and low-risk categories. The frequency of high-risk genotype, DRB1*03-DQB1*0201/DRB1*04-DQB1*0302, decreased with increasing age of onset (p < 0.0001, chi(2) linear trend). The presence of the high-risk genotype was independently associated with lower C-peptide levels at diagnosis (p = 0.002). In the regression analysis of C-peptide levels, the standardized beta coefficient for age of onset and high risk compared to low-risk genotypes showed similar results (0.27 and 0.24 respectively). There was a positive association between age of onset and C-peptide (p < 0.0001) and a negative association between age of onset and insulin requirement (p < 0.0001). CONCLUSIONS: The degree of beta-cell destruction at diagnosis of T1DM is independently associated with both, age of onset and HLA genotypes, the two variables exert a similar quantitative effect on residual beta-cell function at diagnosis.

Adolescent↗
PubMedDate not supplied

An immunocytochemical analysis of torn rotator cuff tendon taken at the time of repair.

During rotator cuff repairs, it is recommended that the hypovascular tissue edge be resected. To investigate rotator cuff tendon histopathology, we performed immunohistochemistry on 8 surgical and 6 cadaveric specimens. Hoechst nuclear stain and standard hematoxylin-eosin were used for morphologic analysis. Antibody to human von Willebrand factor tagged with fluorescein isothiocyanate, conjugated, was used to visualize vascularity, and antibody to human procollagen type I tagged with Cy3 was used to visualize new procollagen synthesis. There were no significant differences in the vascularity of surgical specimens sectioned near the tear site (<2.5 mm from tear margin) and matched cadaveric controls. However, sections taken 2.5 to 5 mm away from the tear demonstrated more vessels than those taken from either control or surgical specimens within 2.5 mm of the tear (P <.001). There were no differences in nuclear distribution patterns or in procollagen production and distribution between surgical specimens from sites near the tear or away from the tear. On the basis of morphologic architecture, these data suggest that minimal debridement of tendon edges only is required to maximize healing of the rotator cuff tendon at the time of repair.

Aged↗