Biomedical subjects

M E Meistrell

Publications and source records attributed to M E Meistrell.

7 recordsLinked to original sources

PubMed1997

Tumor necrosis factor is a brain damaging cytokine in cerebral ischemia.

Two contrasting roles, one beneficial and the injurious, have been proposed for tumor necrosis factor (TNF) in the pathogenesis of cerebral ischemia. Reported here are results obtained in a standard model of permanent focal cortical ischemia in rats, in which the volume of cerebral infarction is measured after permanent occlusion of the middle cerebral artery. Administration of neutralizing anti-rat TNF antibodies (P114) into the brain cortex significantly reduced ischemic brain damage (85% reduced infarct volume as compared with preimmune-treated controls). Similar results were achieved by systemic administration of CNI-1493, a recently described tetravalent guanylhydrazone compound, which effectively inhibited endogenous brain TNF synthesis and conferred significant protection against the development of cerebral infarction (80% reduced infarct volume as compared with vehicle controls treated 1 h postischemia with 10 mg/kg). P114 anti-TNF and CNI-1493 were each cerebroprotective when given within a clinically relevant time window for up to 2 h after the onset of ischemia. These findings establish an important, pathophysiological role of TNF in mediating the progression of ischemic brain damage, and suggest that inhibiting TNF with CNI-1493 may be beneficial in the future treatment of stroke.

Animals↗

PubMed1997

Expression of TNF and TNF receptors (p55 and p75) in the rat brain after focal cerebral ischemia.

Cerebral ischemia induces a rapid and dramatic up-regulation of tumor necrosis factor (TNF) protein and mRNA, but the cellular sources of TNF in the ischemic brain have not been defined. The diverse activities of TNF are mediated via ligand interaction with two distinct receptors, p55 and p75, which activate separate intracellular signal transduction pathways, leading to distinct biological effects. Since the effects of cerebral ischemia on TNF receptor (TNFR) expression are unknown, we examined the cellular localization and protein expression of TNF and its two receptors in the rat cerebral cortex in response to permanent middle cerebral artery (MCA) occlusion. The results indicate that focal. cerebral ischemia up-regulates expression of TNF and both TNFRs within the ischemic cortex. The most abundant type of TNF immunoreactivity (IR) was a punctate and filamentous pattern of transected cellular processes; however, cell bodies of neurons, astrocytes, and microglia, as well as infiltrating polymorphonuclear (PMN) leukocytes also showed TNF IR. Brain vasculature displayed TNF IR not only within endothelial cells but also in the perivascular space. MCA occlusion induced significant up-regulation of TNF receptors, with p55 IR appearing within 6 hr, significantly before the appearance of p75 IR at 24 hr after the onset of ischemia. Since p55 has been implicated in transducing cytotoxic signalling of TNF, these results support the proposed injurious role of excessive TNF produced during the acute response to cerebral ischemia.

Animals↗

PubMed1995

Reliability of computer-generated prediction tracing.

The reliability of a commercially available computer prediction program (Quick Ceph II) was evaluated using pretreatment and posttreatment cephalograms of 30 patients who were treated during an active period of growth. The computer prediction was compared with the actual treatment result, and the growth forecast with the computer program was compared with the growth forecast using a manual method. Using paired student's t-tests, predictions for 5 of the 10 variables measured were found to be statistically reliable. Comparing the relative accuracy of growth prediction in terms of absolute values, the computer came closer to the actual result in four of the nine variables, while the manual method came closer in three variables. Predictions for the other two variables were virtually the same using both methods. The manual method of prediction was sufficient to give a reasonably good graphic representation of growth changes to create a VTO. However, the computer offers the added advantages of quicker access to information and somewhat greater accuracy in producing the tracing, as well as its use in patient education.

Adolescent↗

PubMed1988

A cephalometric appraisal of edgewise Class II nonextraction treatment with extraoral force.

The purpose of this study was to determine the treatment effects of nonextraction edgewise therapy combined with cervical headgear on Class II, Division 1 malocclusions. Data from a sample of 43 treated patients with a mean age of 11 years 11 months and a mean treatment time of 2 years 8 months were recorded. A cephalometric appraisal was done and the initial and final measurements of points, lines, and angles based on accepted cephalometric analyses were compared. Student's t test for paired cases was used to evaluate the significance of all measurement changes. The significant findings were as follows: the inhibition of forward growth of the maxilla, downward tipping of the anterior part of the palate, reduction of flaring of the maxillary incisors, reduction of the facial convexity, and extrusion and mesial movement of maxillary and mandibular first molars. The overall results tend to indicate the efficacy of this treatment modality in the treatment of the Class II, Division 1 malocclusion.

Cephalometry↗

PubMed1988

Treatment objectives and planning in compromised adult cases.

The compromised adult orthodontic patient requires a coordinated, multidisciplinary approach to treatment to achieve the ideal resolution of the existing dental problems. Careful analysis of complete orthodontic records will define the scope of the problem and suggest treatment alternatives. Case presentations are used to demonstrate the principles of diagnosis and treatment planning.

Adult↗

PubMed1986

A cephalometric appraisal of nonextraction Begg treatment of Class II malocclusions.

Initial and final cephalometric evaluations are compared in a sample of 42 patients with Class II malocclusions treated in a nonextraction manner with the Begg appliance. The sample was analyzed as a group. Subgroups of patients with Division 1 and Division 2 characteristics were analyzed separately. To depict skeletal and dental changes, measurements were made using the sella nasion, palatal, and mandibular planes as reference planes. The findings show that on the average: The upper first molar maintained its anteroposterior position at the same time that SNA was reduced. This suggests a restriction of anterior maxillary growth. The mandibular first molar moved forward by 1.2 mm. Part of this change was attributed to anchorage consumption. Vertical changes in both the maxilla and the mandible were found to be within the normal range. No significant change in occlusal or mandibular plane angles was observed except for the Division 1 subgroup in whom a mild increase in the mandibular plane angle was observed.

Adolescent↗

PubMed1982

A cephalometric evaluation of hard- and soft-tissue changes during the third stage of Begg treatment.

This study examined the effect of lingual root torque during the third stage of Begg treatment upon the maxillary central incisor, hard-tissue Point A, and soft-tissue Point A. Lateral cephalograms were taken, at the beginning and end of Stage III, of eighteen patients undergoing Begg treatment. Linear and angular measurements were made in an attempt to find the anteroposterior changes which occurred in the above structures as well as the superior-inferior changes which occurred in the maxillary first molar and the maxillary central incisor. It was found that the apex of the maxillary incisor, Point A, and soft-tissue Point A moved posteriorly a significant amount following Stage III mechanics. Also, the incisal edge of the maxillary central incisor moved anteriorly and extruded significantly. Weak correlations between hard- and soft-tissue changes may be due to changes in thickness of the upper lip related to growth and to growth of the nose.

Adolescent↗