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Biomedical subjects

C Hales

Publications and source records attributed to C Hales.

13 recordsLinked to original sources
PubMed2000

Congruent spinopelvic alignment on standing lateral radiographs of adult volunteers.

STUDY DESIGN AND OBJECTIVES: Radiographs of 75 healthy volunteers were measured to decide parameters and ranges for "congruent" sagittal spinopelvic alignments using the pelvic radius technique. A subset of 30 of the volunteers subsequently had a second radiograph to assess for changes in the repeated measurements. SUMMARY OF BACKGROUND DATA: Measurement of spinal alignment is important. Radiographic parameters for "congruent" spinopelvic balance over the hips and changes in sagittal spinal alignments over time have not been defined. Measurement techniques for spinal alignments and to quantitate pelvic morphology need to be standardized. METHODS: The 75 volunteers (44 men/31 women, mean age 39 years, range, 20 to 63 years) had 36-inch standing lateral radiographs of the thoracolumbar spine and pelvis taken that included both hips. Thirty volunteers (19 men/11 women) had a second radiograph taken 5 to 6 years later. Radiographic measurements were made using the pelvic radius technique. This required locating a midpoint between the approximate centers of both femoral heads to establish a pelvic hip axis. A line between the hip axis and the posterior superior corner of S1 for the pelvic radius was drawn and measured for length. Angles were measured from the pelvic radius to tangents along the vertebral endplates on the 105 films with an electronic digital readout device. These angles included PR-S1 for pelvic morphology and PR-T12 for total lumbopelvic lordosis. A pelvic angle was measured from a vertical line through the hip axis to the pelvic radius. This angle gave the sagittal alignment for the pelvis over the hips. Longitudinal measurements between radiographs were compared for minimum and maximum change. Significant statistical correlations for the measurements were carefully studied to determine potentially important clinical relationships. In addition, thoracic kyphosis/lumbar lordosis ratios were assessed. RESULTS: The most constant measurement with the least change on the repeated radiographs was that for pelvic morphology (PR-S1 angle) followed by length of the pelvic radius, pelvic alignment over the hips (pelvic angle), and total lumbopelvic (PR-T12) and lumbosacral (T12-S1) lordosis. Other longitudinal measurements, including those for thoracic kyphosis and spinal balance by a plumbline, showed greater change. Measurements for pelvic morphology by the pelvic radius technique were correlative with standing total lumbosacral lordosis, regional lumbopelvic lordosis, pelvic alignment, pelvic radius length, and gender (P< or = 0.006 for each). The correlations between total and regional lumbopelvic lordosis and pelvic alignment measurements were even higher(P<0.0001). Of possible clinical importance was the finding that standard measurements for lordosis were dependent on individual pelvic morphology quantitated by the pelvic radius technique. CONCLUSIONS: In all of the sagittally balanced subjects studied, "congruent" spinopelvic alignment on all 105 standing lateral radiographs could be defined by four parameters using the pelvic radius technique: total lumbopelvic lordosis (PR-T12), incorporating complementary angles for lumbosacral lordosis (T12-S1), and pelvic morphology (PR-S1 angle) that summarily were always between -69 degrees to -116 degrees (+/-3 degrees ); centered pelvic alignment over the hips, as determined by the pelvic angle, that was always between -3 degrees to -32 degrees (+/-2 degrees ); compensated spinal balance, with a sagittal plumbline from the center of the T4 body always posterior to the hip axis as well as the center of the L4 vertebral body; and a concordant T4-T12 kyphosis/PR-T12 lordosis ratio that was always negative and between 0.15 to 0.75. [Key words: congruent alignment, pelvic radius technique, pelvic morphology, lumbopelvic lordosis, lumbosacral lordosis]

Adult↗
PubMed2000

Lumbopelvic lordosis and pelvic balance on repeated standing lateral radiographs of adult volunteers and untreated patients with constant low back pain.

STUDY DESIGN: Twenty volunteers and 20 patients with no prior spine surgery had two standing lateral radiographs taken, on the average, 66 months apart and 2 weeks apart, respectively. OBJECTIVES: To first determine the reliability of the measurement techniques used, and then the longitudinal variation between radiographs for the sagittal spinopelvic alignments measured in two stable populations, the one manifesting no back symptoms (volunteers) and the other showing no changes in symptoms (patients). Pelvic morphology also was assessed quantitatively, and significant correlations for the measurements were studied. SUMMARY OF BACKGROUND DATA: There are no published studies on longitudinal variation for measurements of sagittal spinal alignments in asymptomatic control subjects or untreated patients with stable back problems. It may be helpful to know not only how much variation in alignments can be expected between radiographs of the same individual, but also which measurements and measurement techniques offer the greatest clinical reliability and application. METHODS: Each patient in this study reported mechanical type low back pain that was constant in location and character as well as clinically consistent with symptomatic degenerative lumbar disc disease. Each patient and volunteer had 36-inch-long lateral radiographs taken of the entire thoracic and lumbar spine, which included the pelvis. After intervening periods of 1 to 4 weeks (patients) and 5 to 6 years (volunteers), a second radiograph was taken for comparison. Two observers made 24 different measurements on the radiographs including determinations for lumbopelvic lordosis, pelvic balance, and pelvic morphology using the pelvic radius technique. Reliabilities, longitudinal variations, and correlations for the measurements were compared. RESULTS: The most reliable measurements were for pelvic morphology, pelvic balance, and regional lumbopelvic lordosis by the pelvic radius technique. Pelvic morphology was the most constant measurement between individual radiographs. Pelvic morphology and total lumbosacral lordosis were dependent measurements that were complementary in determining total lumbopelvic lordosis. Lumbopelvic lordosis and pelvic balance also had strong correlation, whereas lumbosacral lordosis and pelvic balance were independent measurements. CONCLUSIONS: The pelvic radius technique is recommended for evaluating lordosis to the pelvis because this approach provided not only good measurement reliability on standing radiographs for lumbopelvic lordosis, but also determination of pelvic balance over the hips and the option to assess pelvic morphology quantitatively. Lumbopelvic lordosis and pelvic balance were strongly correlative. This finding, along with higher reliability and lower longitudinal variation on repeated radiographs, indicated greater clinical application for these specific measurements.

Adult↗
PubMed1998

Compensatory spinopelvic balance over the hip axis and better reliability in measuring lordosis to the pelvic radius on standing lateral radiographs of adult volunteers and patients.

STUDY DESIGN: Sagittal alignments, including lumbar lordosis and spinopelvic balance (measured from C7, S1, and hip axis reference points for the relative positions of the spine and sacropelvis over the hips), were studied on standing 36-in. lateral radiographs of adult volunteers (control subjects) and patients who had specific spinal disorders. OBJECTIVES: To determine the most reliable methods for measuring lumbopelvic lordosis and to define significant spinopelvic compensations for sagittal balance. SUMMARY OF BACKGROUND DATA: Measurements for standing sagittal balance, obtained using a C7 plumb line, and segmental angulations of the spinal vertebrae, including lordosis to the sacrum, have been reported. Absolute values, even for normative data, have had wide variation and limited clinical usefulness. Correlations of sagittal balance with the reported spinopelvic angulations (spinal vertebral and sacropelvic angulations) have not been well defined. In addition, determinates of balance (spinal and pelvic) have not been studied for reliability, and compensatory mechanisms for maintenance of balance have not been carefully evaluated. Better recognition of the correlations and more reliable methods to measure lordosis and balance and the spinopelvic compensations for its maintenance may be beneficial in treating patients who have spinal disorders. METHODS: Measurements on standing 36-in. lateral radiographs were made for sagittal alignments in adult volunteers (n = 50) and in adult patients who had symptomatic degenerative lumbar disc disease (n = 50), low grade L5-S1 isthmic (lytic) spondylolisthesis (n = 30), and idiopathic or degenerative scoliosis (n = 30). All participants exhibited clinical compensation for balance. Data were analyzed for significant correlations within each group to determine compensatory correlations of spinopelvic balance with the other sagittal alignments. Intraobserver and interobserver reliability for the parameters evaluated were calculated. This included two methods for determining lordosis (S1 end-plate and pelvic radius techniques). RESULTS: Plumb line measurements for balance from the S1 and hip axis reference points, as defined, were similar in all four groups. However, the groups appeared to adjust for balance by using common and distinctive spinopelvic compensations that resulted in significantly and characteristically different angular alignments among the four groups. Lordosis and balance measurements were closely correlated, and the correlation was characterized by pelvic rotation and translation around the hip axis. The subjects with less lordosis typically stood with the C7 plumb line anterior to and at a longer distance from the sacral reference point. This was primarily because of posterior sacropelvic translation around the hip axis and not because the sagittal plumb line initially moved anteriorly away from the sacrum. This was true in all four groups and gave the appearance that the sacropelvis was less well balanced over the hips in the subjects with less lordosis. Even small differences in lordosis appeared to be associated with considerable adjustments in the other spinopelvic alignments. Therefore, it was important to determine that lordosis was lumbopelvic more reliably measured by the pelvic radius technique. CONCLUSIONS: Lower lumbar lordosis, by the pelvic radius technique, and compensatory sacropelvic translation around a hip axis, in addition to measurements from this axis to the C7 plumb line, were the primary determinates and most reliable radiographic assessments for sagittal balance. Understanding the common and characteristically different compensations that occur with balance in these patients who had specific spinal disorders may help to improve their care.

Adult↗
PubMed1995

Bronchoalveolar lavage fluid phospholipase A2 activities are increased in human adult respiratory distress syndrome.

The role of phospholipase A2 (PLA2) in lung injury in humans is unclear. Previous studies have failed to identify an increase in PLA2 activity in bronchoalveolar lavage fluids (BALF) of patients with the adult respiratory distress syndrome (ARDS). In this study, increased phospholipase A2 (PLA2) activity was detected in BALF from patients with ARDS. PLA2 levels in BALF correlated positively with lung injury score in patients with lung disease. BALF PLA2 activity in patients with ARDS was resolved into heparin binding and nonbinding activities. Both PLA2 activities were increased in BALF of ARDS patients. The PLA2 activity that bound to heparin was identified as a group II PLA2 by its chromatographic characteristics, its inhibition by dithiothreitol, its substrate specificity, and its approximate molecular mass of 14 kDa. The second PLA2 activity was further purified and found to require Ca2+ at a concentration > 2 x 10(-4) M for activity. This form of PLA2 exhibited a neutral and broad pH optimum (pH 6.0-8.0) and hydrolyzed both phosphatidylethanolamine and phosphatidylcholine effectively. Its apparent molecular mass was estimated to be 80-90 kDa. Neither anti-pancreatic PLA2 antiserum nor anti-pig spleen cytosolic 100-kDa PLA2 antiserum immunoprecipitated the enzymatic activity. Thus at least two forms of PLA2 are increased in activity in BALF of patients with ARDS, a group II PLA2 and a biochemically and immunochemically form distinct from group I, group II, and cytosolic PLA2. Increased lung PLA2 activity may be important for the pathophysiology of ARDS.

Adult↗
PubMed1988

Pulmonary function of haplotype-matched and mismatched allografts in dogs treated with total-body irradiation, autologous marrow transplantation, methotrexate, and donor blood.

Seven beagle recipients surviving 2-11 years after allotransplantation of a left lung were available for study of pulmonary function. Significant reductions of ventilation and perfusion to the transplanted lung were documented by radionuclide scanning. These reductions in function were well-matched, however, and allowed relatively normal gas exchange, as measured by VD/VT, arterial PO2 and shunt fraction. The vasoconstrictor response of the transplanted lung to both hypoxia and stellate ganglion stimulation was comparable to that of the native lung. An abnormal rise in graft pulmonary vascular resistance and fall in PaO2 when the normal lung was made hypoxic suggest an inability of the transplanted lung to vasodilate and recruit blood vessels normally in response to increased blood flow. The animals were sacrificed at the conclusion of the pulmonary function testing. Pathologic study of the transplanted lungs showed minimal changes of rejection in spite of the fact that these recipient animals received no immunotherapy after the second posttransplant week.

Animals↗
PubMed1986

Ibuprofen prevents synthetic smoke-induced pulmonary edema.

Multiple potentially injurious agents are present in smoke but the importance of each of these agents in producing lung injury as well as the mechanisms by which the lung injury is produced are unknown. In order to study smoke inhalation injury, we developed a synthetic smoke composed of a carrier of hot carbon particles of known size to which a single known common toxic agent in smoke, in this case HCI, could be added. We then exposed rats to the smoke, assayed their blood for the metabolites of thromboxane and prostacyclin, and intervened shortly after smoke with the cyclooxygenase inhibitors indomethacin or ibuprofen to see if the resulting lung injury could be prevented. Smoke exposure produced mild pulmonary edema after 6 h with a wet-to-dry weight ratio of 5.6 +/- 0.2 SEM (n = 11) compared with the non-smoke-exposed control animals with a wet-to-dry weight ratio of 4.3 +/- 0.2 (n = 12), p less than 0.001. Thromboxane B, and 6-keto-prostaglandin F1 alpha rose to 1,660 +/- 250 pg/ml (p less than 0.01) and to 600 +/- 100 pg/ml (p greater than 0.1), respectively, in the smoke-injured animals compared with 770 +/- 150 pg/ml and 400 +/- 100 pg/ml in the non-smoke-exposed control animals. Indomethacin (n = 11) blocked the increase in both thromboxane and prostacyclin metabolites but failed to prevent lung edema.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1981

Regional lung function evaluation with nitrogen-13.

Regional ventilation and perfusion studies are routinely performed with molecular nitrogen-13 (a short-lived positron emitter), a multicrystal positron camera, and a computer. These studies have the advantage of viewing with equal sensitivity all sections of the lung simultaneously. Nitrogen-13 is less soluble than xenon in blood and therefore allows more accurate ventilation imaging. The short half-life of the radiopharmaceutical allows simultaneous ventilation and perfusion scintigraphy of the lung. Unlike other imaging techniques in which the residual radioactivity persists in the lung for hours, nitrogen-13 is rapidly cleared allowing repetitive imaging. Ventilation and perfusion studies are part of the routine preoperative evaluation for lung cancer resection or for bullectomy in patients with chronic obstructive pulmonary disease and for assessment of pulmonary emboli in the presence of chronic obstructive disease.

Adult↗
PubMed1978

N13-N2(1).

13N when coupled with a positron camera allows excellent quantification and imaging of regional lung function. The studies can be readily repeated since the half-life of the 13N is uncer 10 min and the radiation dose to the patient with each study is low. The very low solubility of 13N not only enhances lung imaging but reduces total body radiation by remaining confined to the lung.

Adolescent↗
PubMed1975

Three-dimensional reconstruction of lung perfusion image with positron detection.

Transverse section images of the distribution of pulmonary perfusion in a canine have been obtained using microspheres labeled with the positron-emitting isotope 68Ga and a three-dimensional reconstruction technique. The reconstruction method is more accurate than conventional tomographic procedures and is facilitated by the use of positron detection. The transverse sections presented demonstrate the capacity of the technique to delineate reduction in regional perfusion resulting from occlusion of the artery to the left lower lobe.

Animals↗
PubMedDate not supplied

Venovenous bypass with a membrane lung to support bilateral lung lavage.

Partial venovenous cardiopulmonary bypass with a membrane oxygenator was used to exchange respiratory gases during and after bilateral lung lavage in a patient with severe hypoxemia caused by pulmonary alveolar proteinosis. The patient was unable to tolerate an attempt at lung lavage without bypass. Therefore, extracorporeal perfusion safely supported the patient's respiration for 32 hours, buying time to lavage each lung separately and to enable sufficient recovery of transpulmonary gas exchanging capacity.

Cardiopulmonary Bypass↗