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Biomedical subjects

M C Miller

Publications and source records attributed to M C Miller.

At least 19 recordsLinked to original sources
PubMed1992

Rats are not aversive when exposed to 60-Hz magnetic fields at 3.03 mT.

Thirty-two male rats were tested in two replicates of an experiment to determine whether body currents induced by 60-Hz magnetic fields might lead to avoidance behavior comparable to that which results from exposure to strong 60-Hz electric fields. The test apparatus was a two-compartment Plexiglas shuttlebox enclosed in a sound-attenuating plywood chamber, which in turn was encompassed by two copper bus bars that, when energized, served as a source of 60-Hz magnetic fields. Location of the rat, and traverse activity in the shuttlebox were monitored by nine infra-red photo detectors equally spaced along the length of the apparatus. Rats were divided into 2 groups: 1 group of rats (n = 8 per group per replicate) was sham exposed while rats in the other group (n = 8 per group per replicate) were exposed to a 3.03 mT (30.3 G), 60-Hz magnetic field whenever they traversed to or were located on the side (L or R) predetermined as the exposed side. To control artifact incident to side preference, the side exposed (L or R) was alternated over the exposed rats. Each rat was tested individually in a 1-h session. A 2-factor ANOVA (exposed vs. control, replicate 1 vs. replicate 2) failed to reveal any significant effects due to either factor or to an interaction between factors. These data demonstrate that rats do not avoid exposure to 60-Hz magnetic fields at a flux density of 3.03 mT and further imply that the avoidance by rats of high level 60-Hz electric fields is mediated by something other than the internal body currents induced by the exposure.

Animals↗
PubMed1992

The antineoplastic and cytotoxicity of benzohydroxamic acids and related derivatives in murine and human tumor cells.

Benzohydroxamic acids proved to be potent cytotoxic agents suppressing the growth of a number of murine and human cell lines grown in tissue culture, e.g. leukemia, colon, uterine and glioma. Selected compounds demonstrated activity against the growth KB nasopharynx, bronchogenic lung, osteosarcoma and skin cancer. In vivo activity against Ehrlich ascites carcinoma growth was shown with certain compounds. In L1210 cells compound 2 inhibited DNA synthesis significantly within 60 min. the site of action of the agent appears to involve the purine de novo synthesis pathway at PRPP amido transferase and IMP dehydrogenase. Dihydrofolate reductase and nucleoside kinase activities were inhibited by the agent. The levels of d(NTP)s in L1210 cells were reduced after drug treatment. The drug did not appear to affect the DNA template directly causing any damage which might alter transcription and replication nor was there any inhibition of HeLa topoisomerase activity by the drug. Thus the drug appears to be a metabolic inhibitor of nucleoside metabolism.

Animals↗
PubMed1992

Chronic-pain medications: equivalence levels and method of quantifying usage.

Medication use is an important consideration in chronic-pain rehabilitation programs (CPRPs). However, it is difficult to quantify this aspect of chronic-pain treatment, because patients often take multiple medications that can differ by pharmacological class as well as dosage level. The Medication Quantification Scale (MQS) provides a method for quantifying medication use in patients with chronic, nonmalignant pain. Scores are calculated for each medication based on weights assigned by medication class and dosage level, and these scores are summed to provide a quantitative index of total medication usage suitable for statistical analysis. The method for calculating MQS scores is illustrated, and research data on MQS reliability and validity are presented. Interrater reliability was rho = 0.985 (p less than 0.0001) for 30 MQS scores calculated by two clinicians. MQS scores for 88 patients correlated well with the clinical judgment of 12 health care professionals (mean rho = 0.755, p less than 0.0001). The MQS scores for 60 chronic-pain patients (30 treated in a CPRP and 30 untreated) were obtained at two time points: evaluation and 1-year follow-up. A two (groups) by two (time points) analysis of variance yielded a significant group-by-time interaction (F = 8.82, p less than 0.0043). Treated patients decreased their medication intake significantly (p less than 0.0001), whereas untreated patients did not (p greater than 0.57). The MQS offers a reliable and valid method for quantifying medication usage in chronic-pain patients.

Analgesics↗
PubMed1991

Quantification of cervical change: relationship to preterm delivery in the multifetal gestation.

Prematurity is the major contributor to the very high perinatal morbidity and mortality associated with multifetal gestations. Antepartum cervical evaluation has been suggested as a way to better define the risk of preterm delivery in multifetal gestations. Weekly digital cervical examinations were performed in 86 twin and 7 triplet gestations that were being monitored in a special antepartum clinic. A cervical score was calculated from each examination by subtracting cervical dilatation in centimeters from cervical length in centimeters. Cervical scores decline gradually with advancing gestation and are influenced by parity and subsequent preterm delivery. Intervals until delivery decrease significantly with lower cervical scores. A cervical score less than or equal to 0 on or before 34 weeks' gestation was strongly predictive of preterm delivery (75%). Only 2 of 78 (2.6%) with a score greater than 0 were delivered within 1 week of the examination. Cervical scoring is a simple, quantifiable, reproducible, and safe method of evaluating preterm delivery risk. An understanding of the prognostic significance of specific cervical scores may be of value in determining the need for obstetric intervention.

Adult↗
PubMed1991

Primary invasive vaginal carcinoma.

A review of primary vaginal carcinoma treated at the Medical University of South Carolina from January 1970 through December 1989 included 76 squamous carcinomas, 12 adenocarcinomas, and 3 undifferentiated carcinomas. Staging was done according to the system of the International Federal of Gynecology and Obstetrics as modified by Perez et al. Stages I, II, III, and IV included 25, 39, 15, and 12 patients, respectively. Corrected 5-year survival rates were 73% for stage I, 39% for stage II, 38% for stage III, and 25% for stage IV. Sixteen percent of patients had received prior pelvic radiation. Invasive cervical cancer preceded vaginal cancer in 21% of patients. Detection of cancer was accomplished by routine cytologic testing in 17% of patients, palpation of an asymptomatic mass in 10% of patients, or palpation of a symptomatic mass in 72% of patients. Eighty-seven percent of patients were treated with radiation therapy. Survival curves of patients grouped by stage and other potential prognostic factors were compared. Lower stage (p less than 0.01), younger age (p less than 0.02), and no symptoms at detection (p less than 0.01) were statistically significant favorable prognostic factors. Histologic type, extent of vaginal involvement, vaginal location, prior radiation therapy, prior cervical cancer, and prior hysterectomy are factors that did not significantly affect survival.

Adult↗
PubMed1991

Cross-sectional analysis of triplet birth weight.

Parameters of fetal growth in triplet gestations are poorly studied and controversial. A cross-sectional analysis of triplet birth weight was performed to elucidate fetal growth patterns. Birth weight and gestational age data were analyzed on 580 infants in 196 triplet sets (eight stillborn infants excluded) between 1985 and 1988. Ovulation induction was used in approximately one half the gestations and early obstetric and ultrasonographic dating was available in all pregnancies. The mean triplet set and individual triplet weights versus gestational age were calculated with distinctly linear growth displayed between 22 to 38 weeks' gestation. Mean intratriplet differences at all gestational ages were determined. A comparison of singleton and triplet growth curves was constructed to show the distinct growth characteristics of triplets.

Birth Weight↗
PubMed1991

Influence of clinical variables on triplet birth weight.

The small size of most reported triplet series has resulted in conflicting statements about the influence of several clinical variables on triplet birth weight. Therefore, obstetrical and neonatal data were collected on 196 mothers and their 580 infants (8 stillbirths excluded). Gestational age was based on the date of fertilization in 13 IVF triplets and on the date of ovulation in 90 medically induced triplets. Obstetrical and ultrasonic criteria were used to estimate the date of confinement in 93 spontaneous triplets. Birth weight appeared to be higher in males and with higher maternal parity, independent of gestational age. The apparent effect of medical technologies such as ovulation induction or IVF on combined triplet birth weight disappeared when maternal parity and fetal gender were controlled. Preeclampsia, maternal race and zygosity were not significantly associated with birth weight. While birth order did not significantly effect ultimate birth weight, the heaviest triplet did present first more often than would be expected by chance alone. Future evaluation of neonatal outcome data in multifetal gestations should control for gestational age, fetal gender and maternal parity. It appears that triplet birth weight is not affected by etiology, which is important given the significant impact of medical technologies.

Analysis of Variance↗
PubMed1991

Prevention of thromboembolic disease following total knee arthroplasty. Epidural versus general anesthesia.

Seventy-two patients were randomized into a prospective clinical trial to evaluate the effects of epidural (EA) versus general anesthesia (GA) on the incidence of thromboembolic disease (TED) following total knee arthroplasty (TKA). Males received aspirin 650 mg po bid and females low-dose warfarin daily to maintain the prothrombin time at 15 to 16 seconds for pharmacologic prophylaxis against TED. Thirty-four patients had EA and 38 GA for their primary TKA. Contrast venography and ventilation-perfusion scanning were performed on the sixth, seventh, and eighth postoperative days, and these were interpreted in a blinded fashion. The mean age of the 45 males and 27 females was 64 years (range, 42-84 years). There were no significant differences between the two groups with respect to hematocrit, operative time, blood loss, number of units transfused, or hospital stay. Twelve of the 34 patients (35%) receiving an EA and 10 of the 38 patients (26%) receiving GA developed TED, an overall incidence of 31% (p greater than 0.05) Fifty-three percent of the clots were located in the popliteal vein above the trifurcation or more proximal. However, the incidence of proximal vein thrombosis was significantly less in patients receiving an EA (46%) rather than a GA (64%). The incidence and distribution of clots was not affected by the type of pharmacologic prophylaxis, gender, or use of methylmethacrylate. Ten percent of the patients had a positive scan by strict criteria and were thought to have a pulmonary embolism (PE). In patients with a femoral vein clot, the incidence of PE was 67%. One bleeding complication occurred in a patient who took double the appropriate warfarin dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Cariostatic mechanisms of fluoride.

Current research findings reveal the mechanisms by which fluoride can prevent caries and heal lesions previously thought to require restoration. The presence of fluoride ions at the enamel surface is key.

Cariostatic Agents↗
PubMed1990

Longitudinal changes in the bone mineral content of term and premature infants.

With the use of photon absorptiometry, bone mineralization was measured at birth and 8 and 16 weeks after delivery in 12 very-low-birth-weight premature (mean +/- SD gestational age, 31 +/- 1.5 weeks) infants who required minimal medical support. Simultaneously, 19 healthy term infants were studied. Throughout the study, each neonate received modified 84-kJ/30 mL formula containing no added calciferol. The recommended daily allowance (400 IU) of calciferol was given to each infant as an oral supplement. Serum 25-hydroxyvitamin D, calcium, phosphorus, and parathyroid hormone concentrations were monitored biweekly and were normal. Bone mineral content and bone width significantly differed at birth between the term and premature infants. However, by 16 weeks after delivery, the premature infants had exceeded the bone mineral status of the term infants at birth, and their bone mineral content was not significantly lower than that of the term infants. These data indicate improved bone mineralization as compared with previously reported data from very-low-birth-weight neonates.

Absorptiometry, Photon↗
PubMed1989

Addition of magnetic field capability to existing extremely-low-frequency electric field exposure systems.

Magnetic field systems were added to existing electric field exposure apparatuses for exposing cell suspensions in vitro and small animals in vivo. Two horizontally oriented, rectangular coils, stacked one directly above the other, have opposite electric currents. This configuration minimizes leakage fields and allows sham- and field-exposure systems to be placed in the same room or incubator. For the in vitro system, copper plates formed the loop-pair, with up to 900 A supplied by a 180:1 transformer. Electric fields were supplied via electrodes at the ends of cell-culture tubes, eight of which can be accommodated by each exposure system. Two complete systems are situated in an incubator to allow simultaneous sham and field exposure up to 1 mT. For the in vivo system, four pairs of 0.8 x 2.7-m coils made of copper bus bar are employed. This arrangement is energized from the power grid via a 30:1 transformer; horizontal magnetic flux densities up to 1 mT can be generated. Pairs of electrode plates spaced 30.5 cm apart provide electric field exposure of up to 130 kV/m. Four systems with a capacity of 48 rats each are located in one room. For both the in vitro and in vivo systems, magnetic exposure fields are uniform to within +/- 2.5%, and sham levels are at least 2,500-fold lower than exposure levels. Potential confounding factors, such as heating and vibration, were examined and found to be minimal.

Animals↗
PubMed1989

Outpatient triplet management: a contemporary review.

The antepartum management of 198 women who were delivered of triplets between 1985 and 1988 is reviewed. Women were managed with the assistance of ambulatory perinatal nursing to provide outpatient surveillance. Modified bed rest, prophylactic tocolysis, and betamethasone were liberally used and patients were hospitalized only when obstetrically indicated. The most common antepartum complication was preterm labor (66.2%) and the success of therapy with tocolytic agents is described. The mean gestational age and birth weight at delivery were 33.6 +/- 3 weeks (mean +/- SD) and 1871 +/- 555 gm, respectively. Comparison of the gestational age distribution at delivery with previous reviews demonstrates fewer deliveries less than 29 weeks' gestation and significantly more deliveries between 32 and 37 weeks' gestation. Cesarean delivery occurred in 94% of the triplets, which eliminated birth order as a factor that affects survival. The corrected perinatal survival rate was 95% in this contemporary review of outpatient triplet management and represents a major improvement in the expected outcome for triplets.

Adult↗
PubMed1989

Factors influencing the penetration of wires into the neural canal during segmental wiring.

We evaluated the influence of the penetration of wires into the neural canal during segmental wiring in a three-part study. First we examined the anatomy of the thoracic spine, specifically the laminar and interlaminar dimensions, as well as the epidural space. In the second part, we evaluated the depth of penetration of wires into the spinal canal at the time of their passage during spinal segmental instrumentation, using direct laboratory measurements for three configurations of the wire: first with a straight wire, and then with two wires of varying curvature. The measurements were repeated after removal of a portion of the lamina. In the third and final part of the study, we assessed the relationship between the observed penetration of the wires and the depth of penetration as calculated using mathematical models for the three wire configurations. When a wire with the largest possible diameter of curvature was passed under the lamina, there was significantly less penetration using the curved-wire configuration. This was seen in calculated models, as well as in normal specimens of the thoracic spine that were obtained from cadavera. Little epidural space was found to be available for passage of the wire. In most instances, passage of the wire must result in contact with and displacement of the dural sac and its contents. To minimize the depth of penetration at any given spinal level, it is recommended that the wire be curved to the maximum degree that will allow it to pass under the lamina.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Shortcomings of a revised feasibility scale for predicting hearing aid use with older adults.

Test-retest reliability and criterion validity of an extensively revised version of the feasibility scale for predicting hearing aid use (FSPHAU) was examined. Twenty-two older adults presenting with symmetrical mild to moderate sensory hearing loss completed the revised FSPHAU (pencil and paper) on two occasions prior to hearing aid fitting. The hearing handicap inventory for the elderly was administered during the fitting session and again six months following aid fitting. Test-retest reliability of the revised FSPHAU is not adequate, as revealed by a significant change in the distribution of scores between administrations. From a clinical standpoint, however, true change in an individual's scores was seen in only 4 subjects. In the absence of reliability, discussion of validity becomes moot. The revised FSPHAU cannot supplant trial use of amplification, as client success was not predicted based upon responses offered prior to aid use.

Adult↗