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Biomedical subjects

J Lemons

Publications and source records attributed to J Lemons.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of costs and referral rates of 3 universal newborn hearing screening protocols.

OBJECTIVE: To investigate the costs and referral rates of 3 universal newborn hearing screening programs: transient evoked otoacoustic emissions (TEOAE), automated auditory brainstem response (AABR), and a combination, two-step protocol in which TEOAE and AABR are used. STUDY DESIGN: Clinical outcomes (referral rates) from 12,081 newborns at 5 sites were obtained by retrospective analysis. Prospective activity-based costing techniques (n = 1056) in conjunction with cost assumptions were used to analyze the costs based on an assumed annual birth rate of 1500 births. RESULTS: Referral rates differed significantly among the 3 screening protocols (AABR, 3.21%; two-step, 4.67%; TEOAE, 6.49%; P <.01), with AABR achieving the best referral rate at discharge. Although AABR had the lowest referral rate at discharge and the highest pre-discharge costs, the total pre- and post-discharge costs per infant screened (AABR, $32.81; two-step, $33.05; TEOAE, $28.69) and costs per identified child (AABR, $16,405; two-step, $16,527; TEOAE, $14,347) were similar among programs. CONCLUSION: Although AABR incurs higher costs during pre-discharge screening, it has lower referral rates than either the TEOAE or two-step program. As a result, the total costs of newborn hearing screening and diagnosis are similar among the 3 methods studied.

Costs and Cost Analysis↗
PubMed2001

The precautionary principle in environmental science.

Environmental scientists play a key role in society's responses to environmental problems, and many of the studies they perform are intended ultimately to affect policy. The precautionary principle, proposed as a new guideline in environmental decision making, has four central components: taking preventive action in the face of uncertainty; shifting the burden of proof to the proponents of an activity; exploring a wide range of alternatives to possibly harmful actions; and increasing public participation in decision making. In this paper we examine the implications of the precautionary principle for environmental scientists, whose work often involves studying highly complex, poorly understood systems, while at the same time facing conflicting pressures from those who seek to balance economic growth and environmental protection. In this complicated and contested terrain, it is useful to examine the methodologies of science and to consider ways that, without compromising integrity and objectivity, research can be more or less helpful to those who would act with precaution. We argue that a shift to more precautionary policies creates opportunities and challenges for scientists to think differently about the ways they conduct studies and communicate results. There is a complicated feedback relation between the discoveries of science and the setting of policy. While maintaining their objectivity and focus on understanding the world, environmental scientists should be aware of the policy uses of their work and of their social responsibility to do science that protects human health and the environment. The precautionary principle highlights this tight, challenging linkage between science and policy.

Decision Making↗
PubMed2001

Implants in regenerated bone in a primate model.

BACKGROUND: Earlier publications from our laboratory described the use of guided bone regeneration to fill large bone voids in the mandible created through en bloc resection in primates. The present report describes placement of implants into the regenerated bone with subsequent prostheses construction and loading. METHODS: Lesions were created in the mandibles of 9 monkeys in a standardized mandibular defect of 8 x 19 mm. Reinforced expanded polytetrafluoroethylene membranes were placed in the animals and held in place with mini screws and sutures for anywhere from 1 to 12 months. No material was added to the defect. In each animal a root-form implant was placed 12 mm distal to the abutment teeth into the regenerated bone and was loaded with a prosthesis for 12 months. These implants were compared to original implants placed in the same monkeys years earlier in the same location in non-regenerated bone. Digital radiology and histomorphometry are described. RESULTS: The results show that root-form implants placed in regenerated bone show the same radiological and histomorphometric characteristics as in normal bone when loaded. In addition, the percentage of bone contact with implants seen in regenerated bone versus non-regenerated bone is the same when both are loaded (65 +/- 13% SD in regenerated bone versus 59 +/- 15% SD in non-regenerated bone). CONCLUSIONS: In a primate model root-form implants placed in regenerated bone and prosthetically loaded show no difference when compared to root-form implants placed in non-regenerated bone and prosthetically loaded.

Alveolar Bone Loss↗
PubMed2000

Enhanced growth of preterm infants fed a new powdered human milk fortifier: A randomized, controlled trial.

OBJECTIVE: A prospective, double-blind, randomized, controlled trial was conducted to evaluate the growth and nutritional status of preterm infants receiving preterm human milk supplemented with a newly formulated powdered human milk fortifier (HMF), study fortifier (SF), or a powdered commercial HMF (CF). METHODS: Infants (n = 144) with a birth weight </=1600 g and gestational age at birth of </=33 weeks were enrolled and randomized before 21 days of life. Study day (SDAY) 1 was defined as the day full-strength fortification (4 packets/100 mL) began and the infant reached an intake of at least 100 mL/kg/day. Growth, biochemical indices of nutritional status, enteral intake, feeding tolerance, clinical histories, and morbidity were assessed serially. The primary outcome variable was weight gain (g/kg/day) from SDAYs 1 to 29 or hospital discharge, whichever came first. RESULTS: Infants fed human milk supplemented with SF consistently grew more rapidly from SDAYs 1 to 29 (or hospital discharge), regardless of whether the statistical analyses were performed on all subjects who were randomized into the study and reached SDAY 1 (intent-to-treat) or were limited to those able to adhere strictly to the feeding protocol of the study (subgroup). Using mean values adjusted for study site (least square [LS] means), the weight gain differences were 2.6 and 3.8 g/kg/day for the intent-to-treat and subgroup analyses, respectively. Likewise, the length-gain differences were.14 and.18 cm/week for the intent-to-treat and subgroup analyses, respectively. Infants in the SF group reached a weight of 1800 g at SDAY 18, and those in the CF group at SDAY 25. Mean alkaline phosphatase values among infants in the SF group were higher than for the CF infants (eg, LS means: 327 U/L vs 272 U/L, intent-to-treat analysis), likely reflecting the more rapid linear growth of the SF infants. Mean serum calcium values tended to be lower in the SF group in the intent-to-treat analysis and were significantly lower in the subgroup analysis (LS means: 10.3 mg/dL vs 11.2 mg/dL). Both fortifiers were generally well-tolerated, although an increased number of infants in the CF group exited the feeding protocol because of gastric residuals and abdominal distention. CONCLUSION: A new powdered HMF was shown to enhance the growth of preterm infants, compared with a commercially available powdered HMF in the United States.

Anthropometry↗
PubMed2000

Guided bone regeneration of large mandibular defects in a primate model.

BACKGROUND: An earlier publication from our laboratory described the use of guided bone regeneration to fill large bone voids in the mandible created through en bloc resection in primates. The present report is an embellishment of this paper and describes bone regeneration experiments in 18 adult male Macaca mulatta monkeys to determine how long membranes must be in position to promote guided bone regeneration. METHODS: Thirty-six lesions were created in the mandibles of 18 monkeys in a standardized mandibular defect of 8 x 19 mm. Reinforced ePTFE membranes were placed in the animals and held in place with mini screws and sutures for anywhere from 1 to 12 months. No material was added to the defect. In addition to clinical studies, digital subtraction radiology and fluorescent labeling with tetracycline and histomorphometry are described. RESULTS: The results indicate that no bone gain was observed in membranes exposed for 1 month or less, but bone gain (approximately well over 90% of defects) was observed at 12 months when membranes were left in situ for 2 to 12 months (P <0.0001). No significant difference in the amount of bone gained at 12 months was observed for membranes left in place for intervals ranging from 2 to 12 months. A significant correlation between the amount of bone gain observed at 3 and 12 months was observed (P <0.0001). CONCLUSIONS: Data therefore suggest that membranes left in situ for 1 month or less result in minimal bone gain compared with membranes left in place from 2 to 12 months. In addition, labeling and stained sections clearly showed that the bone produced after 2 months of membrane placement is mature.

Animals↗
PubMed1999

Comparison of DNA probe technology and automated continuous-monitoring blood culture systems in the detection of neonatal bacteremia.

OBJECTIVE: The present study assessed the ability of a rapid chemiluminescent DNA probe assay to detect bacterial growth in blood culture specimens before their detection by continuous-monitoring blood culture (CMBC) systems. STUDY DESIGN: Three newborn intensive care units, which are members of the National Institute of Child Health and Human Development Neonatal Research Network, participated in this study. Each center employs an automated CMBC system against which the DNA probe was compared. A total of 1700 blood cultures were analyzed. A 3-ml aliquot of culture medium was removed from each culture during early incubation, processed, and analyzed by the DNA probe. RESULTS: Of 1700 blood cultures, 130 (7.6%) were detected positive by a CMBC system. Coagulase-negative staphylococci (CNS) were present in 90 (69%) of the positive cultures, and 26 (29%) were detected by the DNA probe. Other organisms accounted for the remaining 40 positive cultures, and 31 (78%) of these were detected by the probe assay. Seventy-six percent of all positive cultures were detected by a CMBC system within 24 hours. Ninety-eight percent of all positive cultures were detected by a CMBC system within 48 hours. Of the two organisms that grew in a CMBC system beyond 48 hours, both were CNS and one of these was considered a contaminant. Therefore, 99% of clinically significant organisms were detected by a CMBC system within 48 hours. CONCLUSION: This DNA probe is not sufficiently sensitive to be clinically useful; however, automated CMBC systems are sufficiently sensitive to aid in clinical decision-making regarding the continuance or discontinuance of antibiotic therapy following 48 hours of culture incubation.

Bacteremia↗
PubMed1992

Strain-gauge evaluation of lunate unloading procedures.

A biomechanical study was undertaken to determine which procedure(s) most effectively relieve load from the lunate. Strain gauges were mounted on the lunates of 20 preserved cadaveric limbs. Three types of procedures were performed: scaphotrapeziotrapezoid arthrodesis, capitohamate arthrodesis, and ulnar lengthening. Load testing was performed both before and after the simulated fusions and ulnar lengthenings. Ulnar lengthening of 3 mm was the most effective method of lunate strain reduction. Capitohamate arthrodesis decreased compressive strain but increased shear strain. Scaphotrapeziotrapezoid fusion significantly increased both compressive and shear strain in the lunate. Of the three procedures that were tested, ulnar lengthening to create a neutral variance is the most reliable means of unloading the lunate.

Analysis of Variance↗
PubMed1991

The biologic effects of implant materials.

The interaction between implant materials and the surrounding biological environment continues to be an area of intense research and clinical interest. This article presents the information presented in a symposium, held during the 36th Annual Meeting of the Orthopaedic Research Society, in which several important issues concerning the biologic effects of implant materials were discussed. These issues included the mechanisms by which implant materials are released to the surrounding tissues and the ways in which these tissues respond to implant materials. The problem of bone loss around cementless implants was discussed as a specific example of a biologic effect resulting in both bone remodelling and endosteal erosion.

Biocompatible Materials↗
PubMed1989

Absorption of calcium and magnesium from fortified human milk by very low birth weight infants.

Absorption of calcium and magnesium endogenous to human milk, as well as calcium and magnesium added as an exogenous supplement to human milk, was determined in 9 very low birth wt infants. Human milk, intrinsically labeled with stable isotopic tracers of calcium and magnesium, was prepared by administering isotopic tracers intravenously to a lactating woman. Different isotopic tracers, which were representative of calcium and magnesium in the supplement (Enfamil Human Milk Fortifier, Mead Johnson Nutritional Div.), were added to the intrinsically labeled milk. The fortified milk, which was labeled with two calcium tracers and two magnesium tracers, was given orally to the test subjects in a single feeding. True absorption of calcium and magnesium was determined from differences between the doses of tracer ingested and the quantities of tracer excreted in the feces. Stable isotopic tracers were quantified by fast atom bombardment mass spectrometry. These results demonstrate that the fractional absorptions of calcium in the human milk and the added mineral supplement are 80 and 82%, respectively. A total of 89% magnesium endogenous to human milk and 86% of magnesium derived from the mineral supplement was absorbed by the VLBW infants.

Biological Availability↗
PubMed1988

Comparison of cyclic and sustained passive stretching using a mechanical device to increase resting length of hamstring muscles.

The purpose of this study was to compare the effects of cyclic versus sustained passive stretching with a mechanical device on resting hamstring muscles' length. Group 1 subjects (5 men, 17 women) underwent cyclic stretching of their right hamstring musculature, and Group 2 subjects (5 men, 16 women) underwent sustained stretching of their right hamstring musculature. The stretching procedures were performed for 15 minutes on 5 consecutive days. A follow-up examination of the subjects' relative knee flexion range of motion was made one week posttreatment. The Group 1 subjects had a mean ROM increase of 15.4 +/- 5.0 degrees after the five stretching treatments and maintained a mean ROM increase of 10.4 +/- 5.5 degrees on the follow-up examination (p less than .001). In Group 2, the five stretching treatments resulted in a mean ROM increase of 13.4 +/- 4.4 degrees, and a mean increase of 7.9 +/- 4.0 degrees was maintained on the follow-up examination (p less than .001). Linear regression analysis revealed that initial ROM, sex, and treatment method significantly contributed to increases in ROM from Day 1 of treatment to the follow-up examination (F = 6.04; df = 4,36; p less than .0008). The cyclic stretching method resulted in a greater gain in ROM when the other variables were considered. Predicted values of ROM increases were also examined and discussed.

Adult↗
PubMed1986

Biomaterials, biocompatibility, and peri-implant considerations.

There are series of tests recommended for evaluation of dental implants. These materials and instrumentation coupled with the publications reviewed here that deal with animal experimentation and implant experience in humans provide an outline of data that have made tissue response to dental implants more clearly delineated. However, there are several specific aspects of cellular response that remain to be illuminated and correlated with clinical and radiographic signs. The further study of the interface zone with corresponding characterization of materials will produce the final chapter in the development of this most interesting area of dentistry. As stated, no epithelial attachment to any dental implant post has been comprehensively described that utilizes light and electron microscopy or histochemistry. Rather, a concept of a biologic seal has emerged that delineates the external milieu of the mouth with its microbiota and plaque from the internal milieu of bone and connective tissue, where true osseointegration can and does take place.

Animals↗
PubMed1984

Neonatal intracranial hemorrhage and complicating hydrocephalus.

Real-time ultrasound studies of the head were performed on 96 infants weighing 1500 g or less. This population represented all such infants admitted within the first 72 hours of life to a neonatal intensive care unit over a 9-month period. Intracranial subependymal/intraventricular hemorrhage occurred in 22 (23%) of the infants. Of these 13 (59%) developed ventricular enlargement. Four other infants, in whom hemorrhage was not identified, also developed ventricular enlargement. When it occurred, the ventricular enlargement developed within 2 weeks of the hemorrhage in 77% of cases. It reached its maximum size within 2 weeks in 65% of cases. In 9 of 16 cases the maximal ventricular enlargement was categorized as mild. Spontaneous arrest or resolution of the ventriculomegaly occurred in all but two cases, who required shunting. Clot resolution was slow. It was complete at 3 weeks in only 5 of 18 cases.

Cerebral Hemorrhage↗
PubMed1984

Evaluation of the gasless abdomen in the newborn and young infant with metrizamide.

The finding of a gasless abdomen on the abdominal radiograph of an infant over 12 hr old is usually abnormal and may reflect a serious pathologic disorder. Accurate diagnosis is important to plan appropriate therapy. A careful review of the clinical history and the plain chest and abdominal radiographs will often permit an accurate diagnosis to be made. In cases where the diagnosis remains in doubt, contrast studies of the bowel with metrizamide have proved helpful. This report presents six infants with gasless abdomens of unknown cause. In each case, a metrizamide contrast study of the bowel was helpful in providing an accurate diagnosis.

Child, Preschool↗
PubMed1983

A new look at the neonatal bowel-contrast studies with metrizamide (Amipaque).

Metrizamide is the first water-soluble radiographic contrast agent which, because it is nonionic, can be used in isotonic solution and gives good visualization of the desired body structure. Its only major disadvantage is that it is very expensive. Metrizamide can be used to study the neonatal bowel in clinical situations where all the other existing contrast agents are contraindicated. The results of 55 metrizamide studies of the bowel in infants are reviewed. In necrotizing enterocolitis metrizamide aids in confirming or rejecting the diagnosis, identifying patients for surgery, and in evaluating the response to surgery. Metrizamide can identify the etiology in unusual cases of bowel obstruction. Metrizamide correctly identified a thoracic origin of free peritoneal air in four cases and a bowel origin in two cases. It identified bowel perforation in two patients in the absence of pneumoperitoneum. In six patients, the metrizamide study identified the cause for a gasless abdomen. It is concluded that metrizamide has a valuable role to play in evaluating a variety of neonatal bowel disorders.

Drug Evaluation↗