PubMed Health⌕ Search

Biomedical subjects

M W Meyer

Publications and source records attributed to M W Meyer.

At least 37 records · Page 2Linked to original sources
PubMed1982

Regional cerebral blood flow correlates of auditory processing.

To study the regional cerebral blood flow (rCBF) correlates of auditory processing, we performed rCBF measurements in young, normal right-handed volunteers engaged in listening tasks. Using the xenon Xe 133 inhalation technique, rCBF was measured in 11 regions in each hemisphere. Compared with a baseline condition, significant rCBF increases in the left posterior Sylvian regions were associated with both verbal phonologic processing and nonverbal acoustic processing. Verbal semantic processing was associated with unilateral increased rCBF in the posterior Sylvian region contralateral to the hand used for response signaling. Comparison of rCBF from homologous regions of the two hemispheres also confirmed a clear difference between the rhyme detection and meaning detection tasks, with the former strongly lateralized to the left hemisphere. Thus, changes in rCBF were related to the nature of the listening task.

Acoustic Stimulation↗
PubMed1981

Evaluation of local blood flow after total maxillary osteotomy.

The radioactive microsphere method was used to quantitate blood flow to selected maxillary tissues before and during left-side cervical sympathetic stimulation in a group of 15 macaque monkeys, nine of which received Le Fort osteotomies. The sympathetic system to regulate blood flow appears to have been modified and has not returned to its normal regulatory status six weeks after the operation.

Animals↗
PubMed1978

Blood flow and oxygen consumption in steroid-treated dental pulps.

This study examined pulpal blood flow and oxygen consumption by the dental pulps of dogs. Blood flow was measured by the radioactive microsphere method and oxygen uptake was determined by the indirect Warburg approach. These variables were assessed 2 days after the canine teeth had been exposed and treated with either a cotton pellet impregnated with 1 per cent prednisolone or normal saline. The analysis indicated that the pulpal blood flow as well as the oxygen consumption did not differ between the steriod-treated tooth and the corresponding saline-treated tooth in the same jaw.

Animals↗
PubMed1978

Quantitation of blood flow after anterior maxillary osteotomy: investigation of three surgical approaches.

The radioactive microsphere method was used to quantitate preoperative and postoperative blood flows in macaque monkeys when three different surgical approaches for anterior maxillary osteotomy were performed. Despite distinct variations in flap designs among the experimental groups, preoperative and postoperative determinations of blood flow were essentially unchanged. Results of the study suggest that a palatal, labial, or combined mucoperiosteal pedicle should be adequate to preserve the flow of blood to tissues in the osteotomized segment.

Animals↗
PubMed1977

Tonometric measurement of dental pulpal and mandibular marrow blood pressures.

Dental pulpal and mandibular marrow vascular pressures were studied with a tonometric method under conditions of autoperfusion and step flow controlled perfusion. The tonometric pulpal and marrow pressures averaged 17 +/- 5 mm Hg and 20 +/- 6 mm Hg, respectively. The venous end pressure was 16 +/- 8 mm Hg at a perfusion pressure of 156 +/- 28 mm Hg. The tonometric pulpal pressures were lower and were less variable than the comparable canulation pulpal pressures.

Animals↗
PubMed1977

Quantification of pulpal blood flow in developing teeth of dogs.

Pulpal blood flow was determined in 32 dogs ranging in age from 6 weeks to 18 months by the isotope fractionation method incorporating diffusible and nondiffusible tracers. Dogs were placed into selected age groups by the developmental status of the canine teeth. For the teeth sampled, the maxillary first, second, and third incisors along with the canines and first molars, pulpal blood flow was determined to be not different in teeth at various developmental stages. For some dental pulps, alveolar mucosa, and bone, the tracers were not determining equivalent blood flows. Because of incomplete trapping of the 7- to 10 mu microspheres and the flow limitation of 86Rb, the 15 mu spheres would appear to be a reliable indicator of "total" blood flow to pulpal tissues. However, in alveolar mucosa and bone, and 15 mu microspheres may not be completely trapped and thus, may underestimate blood flow to these tissues. Within the age range of these dogs, tissue blood flow was not dependent upon the stages of oral development.

Age Factors↗
PubMed1977

Quantitation of blood flow after Le Fort I osteotomy.

Le Fort I maxillary osteotomies were performed on ten macaque monkeys. The particle distribution method (nondiffusible radioactive microspheres) was used to quantitate local blood flow before and after surgery. Significant reduction in blood flow to the osteotomized maxillary segment was noted in those animals (group S) where the descending palatine vessels were transected. Those animals in which the vascular pedicle was intact (group I) showed decreased blood flow to the attached gingiva and alveolar bone, but palatal tissue blood flow was unchanged or increased. The results reinforce the precept of the importance of maintaining an adequate nutrient pedicle when performing orthognathic surgical procedures.

Alveolar Process↗
PubMed1977

Blood flow changes after sagittal split of the mandibular ramus.

Blood flows to various cephalic tissues were determined by the microsphere method before and after unilateral sagittal split of the mandible in macaque monkeys. Significant blood flow decreases were found in certain bony regions of the osteotomized mandible while blood flow to the masseter and medial pterygoid muscles on theosteotomized side was significantly increased. Judicious stripping of the mucoperiosteum and pterygomassteric sling may be an important consideration when planning the sagittal split approach to correct certain mandibular anomalies.

Animals↗
PubMed1976

Fibroelastic hamartoma (fibroma) of the heart.

Approximately 70 cardiac fibromas (fibroelastic hamartomas) have been reported in the literature and at least 15 have been successfully excised. However there is no well-documented ultrastructural study of these lesions. A successfully excised cardiac fibroma (FEH) was studied by light and elctron microscopy. The tumor was composed mainly of fibroblasts admixed with bundles of collagen and elastic fibers. No muscle fibers were demonstrated in the central region of the tumor either by light or electron microscopy. Mast cells were occasionally present. The lack of encapsulation enabled fibroblasts with collagen and elastic fibers to extend between groups of myocardial fibers at the periphery of the tumor. Within these myocardial fibers ultrastructural changes were limited to the mitochondria and myofibrillar structure.

Child, Preschool↗
PubMed1976

Blood flow changes after orthognathic surgery: maxillary and mandibular subapical osteotomy.

Subapical osteotomies were performed in the left quadrant of the mandibles and maxillas of five dogs and six monkeys. Two indirect methods, the isotope fractionation (diffusible tracer) and particle distribution (nondiffusible tracer--15mu microspheres) were used to quantitate local blood flow. To examine the effect of the surgery, blood flows in the alveolar bone, mucosa, and dental pulp of the segmented left quadrant and the corresponding tissues in the right quadrant were calculated and compared. It was assumed that the blood flows to the nonoperated right quadrant could serve as the controls to those observed in the osteotomized segment. The fractional decrease in blood flows to tissues in the operated sides were similar in both experimental animals. The decrease was largest in the dental pulp, ranging from 54% to 82% on the average, and least for the mucosal tissue, ranging from 18% to 40%. Blood flows decreased by 48% to 74%, on the average, in the alveolar bone. In some animals, blood flow to mucosal tissue that served as the pedicle was actually greater than the blood flow in the corresponding tissue on the right side. After surgery, the cardiac output in the dogs averaged about 156 ml/min/kg as calculated from both the diffusible and nondiffusible data. In the monkeys in which only the microspheres were injected, the cardiac output averaged 99 ml/min/kg. The arterial blood pressure dropped 8 to 13 mm Hg on the average (dog, 108 to 100 mm Hg; monkeys, 94 to 81 mm Hg). The heart rate also decreased slightly in dogs, 158 to 139 beats/min on the average; however, it increased slightly after the surgery in the monkeys, 144 to 161 beats/min. Blood losses during surgery were replaced wtih lactated Ringer's solution and the transient decreases in blood pressure of about 20 to 35 mm Hg were not sufficient to produce any shut down of renal blood flow.

Alveolar Process↗