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Biomedical subjects

L D Haugh

Publications and source records attributed to L D Haugh.

At least 19 recordsLinked to original sources
PubMed1991

Hole preparation techniques for transpedicle screws. Effect on pull-out strength from human cadaveric vertebrae.

In each of eight thoracolumbar human cadaveric vertebrae, a hole was made through one pedicle into the vertebral body with a drill bit and through the contralateral pedicle with a probe. Identical metal screws were implanted into the holes to equal depths, and maximum pull-out force was determined for each screw. Using a paired Student t test, no significant difference (P = 0.87) was found in pull-out strength between the screws implanted into drilled holes and those implanted into probed holes. In fact, the average pull-out strengths for the two groups differed by less than 2%. The pedicular cortex was broken through during hole preparation in 5 of the 16 pedicles: 3 as a result of drilling and 2 secondary to probing. The average pull-out strength of the screws in these five pedicles was 11.0% less than the average pull-out strength of the screws implanted into the contralateral intact pedicles. Although this does not represent a statistically significant difference (P = 0.15), it suggests that damaging the pedicular cortex may weaken pedicle screw fixation.

Aged↗
PubMed1990

Phase I trial of intraperitoneal recombinant interleukin-2/lymphokine-activated killer cells in patients with ovarian cancer.

Ten patients with ovarian cancer refractory to conventional therapy were treated with intraperitoneal (i.p.) recombinant interleukin-2 (rIL-2) and lymphokine-activated killer cells (LAK). The 28-day protocol consisted of 6 priming i.p. rIL-2 infusions on days 0, 4, 6, 8, 10, and 12. Leukapheresis was performed for mononuclear cell collection on days 15, 16, 17, and 18 and lymphokine-activated killer cells were given i.p. with the rIL-2 on days 19 and 21. Three additional i.p. rIL-2 infusions were given on days 23, 25, and 27. Three dose levels of rIL-2 were tested: 5 X 10(5), 2 X 10(6), and 8 X 10(6) units/m2 body surface area. The dose-limiting toxicity was abdominal pain secondary to ascites accumulation with significant weight gain. Other toxic effects included decreased performance status, fever, nausea and vomiting, diarrhea, and anemia. Peripheral lymphocytosis and eosinophilia were seen at all dose levels. The maximum tolerated dose is 8 X 10(6) units/m2/dose. Peripheral and peritoneal IL-2 levels were measured with a bioassay using an IL-2-dependent cell line. At the highest dose level, serum IL-2 was greater than 10 units/ml for 18 h. After the first infusion, a 2-log dilution of the i.p. IL-2 was measured in the serum. In the postleukapheresis i.p. IL-2-dosing period less IL-2 was detected in the serum than in the earlier i.p. IL-2-priming period. The induction and persistence of LAK activity were studied. Peritoneal LAK activity was detected as early as 4 days after the first i.p. infusion, by day 11 in all evaluable patients, and persisted for the 6-day interval between priming IL-2 and LAK/IL-2 infusion. Peritoneal lytic activity persisted until day 28 in 5 tested patients. These peritoneal cells retained lytic activity 48 h in culture medium without rIL-2 present. Peritoneal LAK activity correlated with the percentage of mononuclear cells and the percentage of CD56-positive mononuclear cells in the peritoneum. The yield of peripheral lymphocytes after the six i.p. priming doses of rIL-2 correlated with the dose level of rIL-2 infused. Peripheral blood LAK activity showed a minimal, however progressive, increase during the treatment protocol. LAK activity could be enhanced if rIL-2 was present during the 4-h assay. These studies indicate that i.p. rIL-2 infusion induced durable regional LAK activity and primes peripheral blood cells for LAK activity if exposed briefly to additional IL-2.

Adult↗
PubMed1990

Body height change during upright and recumbent posture.

Body height changes are known to occur in response to changes in loads acting along the spine, such as those produced by movement from a recumbent to an upright posture. Lack of previously available data is addressed here by body height measurements closely spaced in time of ten normal subjects during 8 hours upright and 4 hours recumbent, with particular attention paid to the initial changes. Experimental errors are carefully defined and determined. A Kelvin-unit model is fitted to the mean data for each phase and confidence limits provided for the model equation parameters. Rapid height changes are shown to occur: 26% of the 8-hour loss occurred in the first hour upright, and 41% of the 4-hour recovery occurred in the first hour recumbent.

Adult↗
PubMed1989

Effects of long-term storage on salivary thiocyanate concentration.

The stability of thiocyanate (SCN) concentration in frozen saliva samples stored for up to one year was examined. Fifteen adult smokers and five adult nonsmokers each provided six saliva samples, which were analyzed in duplicate pairs after 0, 2, and 12 months of storage at -20 degrees C in airtight containers. No significant changes in average SCN levels occurred over the storage interval. Although within-subject variability for duplicate samples analyzed at the same time was high, the mean levels in regular smokers were significantly higher than the levels in nonsmokers.

Adult↗
PubMed1989

EMG to torque relationship in rectus abdominis muscle. Results with repeated testing.

Rectus abdominis muscles of young healthy female volunteers were studied to determine both the maximum strength in isometric flexion and the relation between the surface electromyogram (RMS EMG) and torque. Both the upper and lower portions of the abdominal muscle were studied during graded increase and decrease of torque. Repeated testing was performed over 6 weeks. The form of the relation between torque and EMG was better described by a quadratic than by a linear regression relationship, but with considerable variability about the best-fit line. The torque-increasing and torque-decreasing parts of each test were different and were analyzed separately. After 6 weeks of repeated testing, maximum voluntary isometric flexion torque increased 16.8% (P less than 0.01). There was a decrease in the ratio of electromyographic activity to torque production, which was statistically significant in the torque-increasing recordings. These changes in maximum torque and in the EMG-torque relation were attributed to learning through a test-retest effect, rather than to a true change in muscle characteristics. These findings, which show changes in normal subjects undergoing repeated testing, do not support the reliability of isometric strength measurements, or measurements based on RMS EMG recordings, for quantifying abdominal muscle function in patients with back pain, or those undergoing strengthening exercises.

Abdominal Muscles↗
PubMed1989

Preventing alcohol-impaired driving through community self-regulation training.

A community education program was designed to train the individual drinker to self-regulate his or her blood-alcohol concentration (BAC) below a level of impairment (.05 g/dl or 11 mmol/L). Drink calculators (cardboard wheels and wallet cards) were disseminated to customers of bars and licensed beverage outlets; bartenders and counter clerks were trained to demonstrate use of the calculators and demonstrations were presented in television spots. Program components were evaluated in three matched Vermont communities, one receiving the full community education program, one receiving the TV spots only, and one serving as control. After six months of intervention, a roadside survey of nighttime drivers (N = 892) indicated 5.3 per cent fewer drivers with BACs above 0.05 g/dl in the community program group and 1.0 per cent fewer in the TV-only group compared to the control group; however, substantially fewer drivers were found above .00 BAC in either program community than in the control. Drivers reporting heavy drinking and youthful drivers both indicated higher utilization of the materials than did other drivers. Although limited in scale and duration, this study suggests that a community education program can be effective in preventing alcohol-impaired driving.

Adult↗
PubMed1989

Determinants of vocational disability in patients with low back pain.

Eighty-seven unemployed subjects with low back pain were recruited from an orthopedic back pain clinic and were given a battery of physical and psychologic tests. Subjects were contacted six months later to determine their current compensation status and whether they had returned to work. Age, length of time out of work, how much they had lifted in their previous job, the number of weeks they had been compensated, current activity levels, leg pain, and various psychologic factors significantly differentiated those who worked from those who did not. Physical examination findings and testing of the ability to lift were not significantly related to return to work. It is suggested that demographic, job-related, and psychologic factors should be emphasized, rather than only physical capacity, in the evaluation of vocational potential and the assessment of disability in patients with low back pain.

Adult↗
PubMed1988

Phase I clinical and pharmacokinetic study of trimetrexate using a daily x5 schedule.

Trimetrexate (TMQ; NSC 352122) is a potent inhibitor of dihydrofolate reductase with good activity against murine i.p.-implanted B16 melanoma and colon 26 tumors. Preclinical antineoplastic activity, demonstrated schedule dependency, and data suggesting effectiveness against methotrexate-resistant cells prompted a Phase I clinical and pharmacokinetic study of trimetrexate using an i.v. daily x5 schedule. Forty-three good performance status patients were treated with 12 dose levels using daily doses varying from 0.5 to 15 mg/m2/d. Plasma and urine samples were obtained for pharmacokinetic analysis using a high-performance liquid chromatographic method. Myelosuppression was dose limiting and 15 mg/m2/d x5 was the maximum tolerated dose. White blood cell (WBC) and platelet toxicity were noted at doses of 1.6 mg/m2 and above. Median WBC and platelet nadirs occurred on approximately Days 11-12 with recovery by Days 15-18. Nonhematological toxicity included mucositis, nausea and vomiting, stomatitis, diarrhea, and rash. Evidence for antitumor activity was seen in seven patients. Trimetrexate elimination from plasma could be represented as either a bi- or triexponential process. Terminal elimination half-lives were in the range of 5-14 h in patients represented by a triexponential model. Approximately 10-20% of the dose administered was excreted in urine over a 24-h period. The recommended starting dose for patients in Phase II trials using the d x5 i.v. schedule is 8.0 mg/m2/d repeated every 21 days. Dose escalations may be possible depending on the extent of prior therapy and individual tolerance of the drug.

Adolescent↗
PubMed1988

Comparison of acoustic and electrical signals from erectores spinae muscles.

Comparison was made between simultaneous recordings of the electromyogram (EMG) and acoustic myogram (AMG) signals and the torque produced by the lumbar erectores spinae muscles of three healthy subjects while they performed isometric contractions. Repeatability of each signal was studied. The AMG had a relationship to the torque which was more quadratic than linear, whereas that of the EMG was more linear. The coefficient of variability of residuals about a "best-fit" line was 8.55% for torque-increasing EMG recordings and 19.2% for torque-increasing AMG recordings. At the same torque, the EMG was on average about 10% greater for increasing-torque recordings than for decreasing-torque parts of the recordings, but the magnitude of the AMG signal was about 10% less. With repeated testing on the same day, the coefficient of variability of the signal/torque relationship (torque-increasing) was 9% for EMG and 23% for AMG signals. With long-term testing over 2 weeks these coefficients were 23 and 39%, respectively. Correlation analysis showed that the two signal/torque relationships varied independently of each other.

Electromyography↗
PubMed1988

Morphometry of the thoracic and lumbar spine related to transpedicular screw placement for surgical spinal fixation.

Vertebral transpedicular screws provide secure attachment for posterior spinal fixation devices. Screw design details, biomechanics, and implantation safety depend upon anatomic constraints, especially from the pedicle and body. Previous morphometric data were limited; thus, a retrospective study was undertaken using computerized axial tomograms (CT) of 91 vertebrae (T9-L5). In addition, eight cadaver vertebrae were CT scanned and then cut transversely to compare x-ray measurements with direct physical measurements. Measured parameters included pedicle width, pedicle length, angle of pedicle axis to sagittal plane, and transpedicular cortex-to-cortex chord length. Good correlation is shown to occur between CT scan and direct physical measurements of human vertebrae. Implications for spinal implant screw dimensions and safety of implantation are discussed. Comparison with previously available data is made.

Adolescent↗
PubMed1988

Repeatability of four clinical methods for assessment of lumbar spinal motion.

Spinal motion usually is recorded from subjective observation of the fully flexed trunk using a goniometer or the distance from the fingertips to the floor. To quantify functional improvement in the low-back pain patient, the repeatability of four clinical techniques was studied: the common fingertip-to-floor distance; the modified Schober; the two-inclinometer method, and a photometric technique. Ten normal subjects (five men, five women), ages 24 to 34 years old, were examined in full flexion, full extension, and the erect position, both standing and sitting. Repeatability was poor for the fingertip-to-floor method in all postures and for the two-inclinometer method in full flexion. Although other methods for various postures had good repeatability, the modified Schober method of determining lumbar spinal motion was the most repeatable and is recommended for a routine, noninvasive, clinical evaluation of lumbar spinal motion.

Adult↗
PubMed1987

Prediction of arterial blood pressure in the premature neonate using the oscillometric method.

The noninvasive oscillometric measurement of blood pressure (BP) in preterm neonates has become a common practice in intensive care nurseries. The method has gained acceptance primarily through its correlation with direct arterial measurement. In this study, the oscillometric method (using Dinamap 1846) was compared with direct intra-arterial BP monitoring in 15 preterm infants. The 95% prediction intervals for individual oscillometric measurements were wide, ranging from 17 mm Hg for the mean BP to 20 mm Hg for the systolic and diastolic BP. The oscillometric method also underestimated intra-arterial systolic and mean BP and overestimated diastolic BP. Caution must be used when oscillometrically measuring BP in premature neonates.

Blood Pressure Determination↗
PubMed1987

Trunk extensor EMG-torque relationship.

The integrated surface electromyogram (IEMG) of the lumbar erectores spinae and the torque generated were simultaneously recorded from 27 healthy subjects in the standing posture while they pulled isometrically against resistance provided by a harness around the shoulders. The IEMG-torque ratio (efficiency of electrical activity, or EEA) was used to characterize each subject. Individual recordings showed evidence of nonlinearity of the IEMG-torque relationship in that a statistically better fit to experimental recordings was obtained by using two straight lines with a breakpoint between them. However, with repeated testing, the gradients of these two lines were more variable than the slope of the single straight line fitted to the entire recording. The slope of the best fit line (EEA) was less for recordings made during torque decrease than for increasing-torque recordings. This also showed as a "hysteresis" pattern in the recordings. The coefficient of variability (within subjects) of the EEA was greater in day-to-day testing (24%) than with repeated pulls at the same testing session (14%). This was similar to variability of the maximum generated torque. About 25% of the variability between subjects was found to be due to anthropometric differences. The residual variability of the relationship would limit the accuracy of IEMG as a measure of muscular effort under changing torque conditions. However, the EEA may be useful for characterizing muscle performance, especially when maximum effort cannot be achieved.

Adult↗
PubMed1987

Phase I trial of tiazofurin administered by i.v. bolus daily for 5 days, with pharmacokinetic evaluation.

Tiazofurin is a novel C-nucleoside with significant antitumor activity in murine tumor models. In a phase I clinical trial, patients received tiazofurin by bolus iv infusion daily for 5 days. Six doses ranging from 550 to 4100 mg/m2/day were evaluated. Thirty-one treatment courses were initiated in 21 patients. Tiazofurin induced multiple, transient toxic effects at all but the lowest dose level, and treatment interruption was a common result. Nine of 28 treatment courses initiated at doses greater than or equal to 1100 mg/m2/day were interrupted at less than 5 days; only five of eight courses initiated at 1100 mg/m2/day were completed. Symptoms leading to treatment interruption included headache, nausea and emesis, and lethargy and malaise. Other significant, transient toxic effects included skeletal muscle injury manifest as pain, weakness, or serum biochemical abnormalities; mucocutaneous effects; and mental or mood changes. One case each of transient pericarditis and fatal cardiomyopathy occurred at the highest dose. Myelosuppression was observed but was transient and not dose limiting. In addition to leukopenia and thrombocytopenia, unexpected declines in serum hemoglobin were observed, although these were of uncertain significance. Tiazofurin induced significant increases in uric acid production which could be reversed with coadministration of allopurinol. Pharmacokinetic analysis revealed tiazofurin plasma elimination to be at least biphasic, with a beta-half-time of 4.2 hours; most of an injected dose could be recovered from the urine as unaltered compound within 24 hours. From this study we conclude that an appropriate dose for phase II trials with this schedule is less than or equal to 1000 mg/m2/day. The schedule may be a difficult one for clinical evaluation of antitumor activity, however, because of the possibility of frequent treatment interruption due to multiple systemic toxic effects.

Adult↗
PubMed1986

Thermography: a call for scientific studies to establish its diagnostic efficacy.

Thermography is reported to provide objective evidence of physiologic dysfunction in patients with low back pain and sciatica. This diagnostic test is appealing because it is painless, non-invasive, has no known adverse biologic effects, presents comprehensible graphic information, requires only a moderate investment in equipment, and should be an inexpensive procedure to perform. Unfortunately, the complete scientific information necessary to assess its diagnostic reliability is not available. This article discusses other experiments which have been performed to assess the diagnostic accuracy of tests for low back pain and sciatica and outline some features of an experimental protocol which would be essential to establish the reliability of thermography in the diagnosis of low back pain and sciatica due to herniated nucleus pulposus.

Back Pain↗
PubMed1986

An internal fixator for posterior application to short segments of the thoracic, lumbar, or lumbosacral spine. Design and testing.

A new spinal implant has been designed and biomechanical testing completed, intended for application to "short-segment" spinal defects such as disc degeneration, fracture, spondylolisthesis, or tumor. Major improvements over currently available devices include: only 2-3 vertebrae are spanned, not 5-7 as with Harrington rods; true three-dimensional fixation is achieved, preventing such problems as hook or rod dislocation; three-dimensional adjustment is easily accomplished, allowing fracture or spondylolisthesis reduction to be readily performed; attachment to vertebrae is by means of transpedicular screws eliminating deliberate encroachment into the spinal canal, such as Luque wires or Harrington hooks; no special alignment between screws is needed (such as with holes or slots in a plate), allowing screw placement to fully conform to anatomic structures; and laminectomy sites and lumbosacral junction are readily instrumented. Background investigations presented here for design of this device include: CT-defined pedicle morphometry showing that screws may be larger than those currently used; effect of pitch, minor diameter, and tooth profile on screw pull-out strength; mechanical testing of a compact, three-dimensionally adjustable, strong, nonloosening articulating clamp; and establishing of the relationship between depth of penetration and strength of fixation of transpeduncular screws.

Adolescent↗
PubMed1977

Four-year clinical evaluation of a pit and fissure sealant.

The clinical retention of a single application of a pit and fissure sealant was evaluated on the teeth of children to determine the influence that this protective coating, or its loss, would have on caries activity during a four-year period. The sealant was fully retained on 50% of all paired permanent teeth at 48 months. Of the 689 pit regions that retained the sealant, 95% were rated as having severe loss of substance, only 5% as slight loss, and none with no loss of substance. It also was found that 53% of all paired permanent control teeth judged cariesfree at the baseline examination were found to be carious, whereas only 30% of the treated teeth examined were carious. The corresponding relative reduction in caries rates was, therefore, 43%. The actual number of teeth estimated to be saved by the sealant treatment at 48 months, as measured by net gain per 100 teeth treated, was 23. The net gain per child was estimated as 2.7 teeth saved from caries (full mouth), with a positive treatment benefit in 69% of the children. When the sealant remained intact, there was a pronounced reduction in caries initiation--the percent effectiveness being 84%.

Adolescent↗