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Biomedical subjects

J P Bradley

Publications and source records attributed to J P Bradley.

At least 19 recordsLinked to original sources
PubMed2004

Mechanisms of strontium and uranium removal from high-level radioactive waste simulant solutions by the sorbent monosodium titanate.

High-level waste (HLW) is a waste associated with the dissolution of spent nuclear fuel for the recovery of weapons-grade material. It is the priority problem for the U.S. Department of Energy's Environmental Management Program. Current HLW treatment processes at the Savannah River Site (Aiken, SC) include the use of monosodium titanate (MST, with a similar stoichiometry to NaTi2O5 x xH2O) to concentrate strontium (Sr) and actinides. The high affinity of MST for Sr and actinides in HLW solutions rich in Na+ is poorly understood. Mechanistic information about the nature of radionuclide uptake will provide insight about MST treatment reliability. Our study characterized the morphology of MST and the chemistry of sorbed Sr2+ and uranium [U(VI)] as uranyl ion, UO2(2+), on MST, which were added (individually) from stock solutions of Sr and 238U(VI) with spectroscopic and transmission electron microscopic techniques. The local structure of sorbed U varied with loading, but the local structure of Sr did not vary with loading. Sorbed Sr exhibited specific adsorption as partially hydrated species whereas sorbed U exhibited specific adsorption as monomeric and dimeric U(VI)-carbonate complexes. Sorption proved site specific. These differences in site specificity and sorption mechanism may account forthe difficulties associated with predicting Sr and U loading and removal kinetics using MST.

Adsorption↗
PubMed2002

Possible in situ formation of meteoritic nanodiamonds in the early Solar System.

Grains of dust that pre-date the Sun provide insights into their formation around other stars and into the early evolution of the Solar System. Nanodiamonds recovered from meteorites, which originate in asteroids, have been thought to be the most abundant type of presolar grain. If that is true, then nanodiamonds should be at least as abundant in comets, because they are thought to have formed further out in the early Solar System than the asteroid parent bodies, and because they should be more pristine. Here we report that nanodiamonds are absent or very depleted in fragile, carbon-rich interplanetary dust particles, some of which enter the atmosphere at speeds within the range of cometary meteors. One interpretation of the results is that some (perhaps most) nanodiamonds formed within the inner Solar System and are not presolar at all, consistent with the recent detection of nanodiamonds within the accretion discs of other young stars. An alternative explanation is that all meteoritic nanodiamonds are indeed presolar, but that their abundance decreases with heliocentric distance, in which case our understanding of large-scale transport and circulation within the early Solar System is incomplete.

Journal Article↗
PubMed2002

Identification of iron sulphide grains in protoplanetary disks.

Sulphur is depleted in cold dense molecular clouds with embedded young stellar objects, indicating that most of it probably resides in solid grains. Iron sulphide grains are the main sulphur species in cometary dust particles, but there has been no direct evidence for FeS in astronomical sources, which poses a considerable problem, because sulphur is a cosmically abundant element. Here we report laboratory infrared spectra of FeS grains from primitive meteorites, as well as from pyrrhotite ([Fe, Ni](1-x)S) grains in interplanetary dust, which show a broad FeS feature centred at approximately 23.5 micrometres. A similar broad feature is seen in the infrared spectra of young stellar objects, implying that FeS grains are an important but previously unrecognized component of circumstellar dust. The feature had previously been attributed to FeO. The observed astronomical line strengths are generally consistent with the depletion of sulphur from the gas phase, and with the average Galactic sulphur/silicon abundance ratio. We conclude that the missing sulphur has been found.

Journal Article↗
PubMed2001

Auricular reconstruction: indications for autogenous and prosthetic techniques.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Describe the alternatives for auricular reconstruction. 2. Discuss the pros and cons of autogenous reconstruction of total or subtotal auricular defects. 3. Enumerate the indications for prosthetic reconstruction of total or subtotal auricular defects. 4. Understand the complexity of and the expertise required for prosthetic reconstruction of auricular defects. The indications for autogenous auricular reconstruction versus prosthetic reconstruction with osseointegrated implant-retained prostheses were outlined in Plastic and Reconstructive Surgery in 1994 by Wilkes et al. of Canada, but because of the relatively recent Food and Drug Administration approval (1995) of extraoral osseointegrated implants, these indications had not been examined by a surgical unit in the United States. The purpose of this article is to present an evolving algorithm based on an experience with 98 patients who underwent auricular reconstruction over a 10-year period. From this experience, the authors conclude that autogenous reconstruction is the procedure of choice in the majority of pediatric patients with microtia. Prosthetic reconstruction of the auricle is considered in such pediatric patients with congenital deformities for the following three relative indications: (1) failed autogenous reconstruction, (2) severe soft-tissue/skeletal hypoplasia, and/or (3) a low or unfavorable hairline. A fourth, and in our opinion the ideal, indication for prosthetic ear reconstruction is the acquired total or subtotal auricular defect, most often traumatic or ablative in origin, which is usually encountered in adults. Although prosthetic reconstruction requires surgical techniques that are less demanding than autogenous reconstruction, construction of the prosthesis is a time-consuming task requiring experience and expertise. Although autogenous reconstruction presents a technical challenge to the surgeon, it is the prosthetic reconstruction that requires lifelong attention and may be associated with late complications. This article reports the first American series of auricular reconstruction containing both autogenous and prosthetic methods by a single surgical team.

Adolescent↗
PubMed2001

Osteochondritis dissecans of the humeral capitellum. Diagnosis and treatment.

Elbow pain seen in the at-risk athlete, such as a baseball player (in particular, a pitcher) or gymnast, should raise suspicion for OCD. OCD of the humeral capitellum remains a difficult problem to treat. Once radiographic changes are obvious, long-term studies suggest that half of affected individuals will be symptomatic. Currently, the key to successful treatment is early detection. Gymnasts, in general, fare worse in returning to sport. The reason is not entirely clear but is likely related to the amount of force directed across the elbow and the nature of the sport. Pitchers sometimes can be returned, but to another position. Radiographs remain the screening test of choice but can give the surgeon a false sense of security, because changes early in the disease process may not be obvious radiographically. Views at 45 degrees flexion and contralateral elbow views are helpful. The advent of MR imaging now allows the practicing orthopaedic surgeon to assess very early lesions effectively that might otherwise be underappreciated on radiographs. With more advanced lesions, radiographic findings are more obvious and demonstrate the more classic capitellar fragment with a surrounding zone of lucency. MR imaging is this setting is helpful in assessing the overlying articular cartilage and, hence, the stability of the fragment. In the absence of obvious loose bodies or mechanical symptoms, rest is the first step in treatment. If symptoms persist, then operative intervention is indicated. About half of these patients heal with nonoperative treatment. Pretreatment assessment of fragment viability has not traditionally been incorporated into the treatment algorithm. Recent anecdotal evidence suggests that stability and viability of a fragment can be assessed using intravenous contrast. Knowledge of the fragment viability could allow those lesions likely to heal without surgical intervention to be distinguished from those requiring surgical intervention. The procedure should be chosen based on the size of the lesion and the integrity of the subchondral bone. Subchondral drilling and microfracture can only resurface defects and cannot reconstitute subchondral bone. Autologous chondrocyte implantation has limited ability to address subchondral bone loss, whereas autograft and allograft osteochondral transplantation can restore subchondral bone. Most authors would agree that there is no role currently for reduction and fixation of long-standing, free loose bodies. No consensus exists regarding acute dislodging of an in situ loose fragment. Long-term results after radiographic changes are present suggest a degenerative course in about half the patients. Whether the newer techniques of cartilage resurfacing will significantly impact the natural history of this process remains to be seen.

Athletic Injuries↗
PubMed2001

Telemedicine in the sleep laboratory: feasibility and economic advantages of polysomnograms transferred online.

The costs for polysomnography (PSG) and alternative diagnostic procedures for sleep-disordered breathing are challenging public health care systems. We wanted to determine if a telemedicine protocol with online transfer of PSGs from a remote site could be cost-effective and clinically useful while improving patient access to full PSG. Fifty-nine PSGs were performed in 54 pulmonary patients with suspected sleep-disordered breathing at a remote hospital. The data were transferred by File Transfer Protocol (FTP) via the Internet to Walter Reed Army Medical Center (WRAMC) for scoring and interpretation. The results were faxed back to the remote hospital. Clinical utility was assessed by evaluating the reasons for patient referral and the resulting diagnoses. The economic benefits were calculated by comparing direct expenses of the telemedicine protocol with costs for contracting PSGs at outside sleep laboratories. A total of 93% (55) of all PSGs were transferred successfully online. Of the 54 patients, 47 had PSGs performed for diagnosis (including three split-night studies), 8 underwent treatment titration, and 1 patient had both overnight studies. Diagnoses were obstructive sleep apnea in 43 patients, central sleep apnea in 2, and upper airway resistance syndrome in 2. The disease conditions were defined as severe in 27 patients, moderate in 12 patients, and mild in 8 patients. Each PSG cost $700 (including costs for lost transmissions) compared to $1,250 for referral to a private sleep laboratory. A savings of $550 per study was realized with the telemedicine protocol. The online transfer of PSGs from a remote site to a centralized sleep laboratory is technically feasible and clinically useful. Telemedicine offers an effective alternative for cost reduction in sleep medicine while improving patient access to specialized care in remote areas.

Adult↗
PubMed2001

Closure of an oronasal fistula in an irradiated palate by tissue and bone distraction osteogenesis.

Uses for distraction osteogenesis in the craniofacial skeleton have expanded during the last decade. It has become an important rung in the reconstructive ladder for correction of difficult defects. Distraction of irradiated bone has been successfully performed in an animal model but has not been reported in human subjects. We present a case of distraction osteogenesis in a patient with multiple failed reconstructive attempts to close an irradiated palatal defect. An additional benefit included improvement in support of the upper lip from bone transported and the potential for placing dental implants.

Cranial Irradiation↗
PubMed2001

Hyponatremia in the postoperative craniofacial pediatric patient population: a connection to cerebral salt wasting syndrome and management of the disorder.

Hyponatremia after cranial vault remodeling has been noted in a pediatric patient population. If left untreated, the patients may develop a clinical hypoosmotic condition that can lead to cerebral edema, increased intracranial pressure, and eventually, to central nervous system and circulatory compromise. The hyponatremia has traditionally been attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH); however, in our patients the treatment has been resuscitation with normal saline as opposed to fluid restriction (the accepted treatment of SIADH), thus placing the diagnosis of SIADH in question. Patients who developed hyponatremia after intracranial injury or surgery were, until recently, grouped together as having SIADH. However, there are diagnosis and treatment differences between SIADH and another distinct but poorly understood disorder that is designated cerebral salt wasting syndrome (CSW). CSW is associated with increased urine output and increased urine sodium concentration and volume contraction, and it is frequently seen after a central nervous system trauma. We therefore developed a prospective study to evaluate the cause of the sodium imbalance.Ten consecutive pediatric patients who underwent intracranial surgery for various craniosynostotic disorders were postoperatively monitored in the pediatric intensive care unit for hemodynamic, respiratory, and fluid management. The first four patients were evaluated for electrolyte changes and overall fluid balance to determine the consistency with which these changes occurred. The remaining six patients had daily (including preoperative) measurement of serum electrolytes, urine electrolytes, urine osmolarity, serum antidiuretic hormone (ADH), aldosterone, and atrial natriuretic hormone (ANH). All patients received normal saline intravenous replacement fluid in the postoperative period. All of the patients developed a transient hyponatremia postoperatively, despite normal saline resuscitation. Serum sodium levels as low as 128 to 133 mEq per liter (normal, 137 to 145 mEq per liter) were documented in the patients. All patients had increased urine outputs through the fourth postoperative day (>1 cc/kg/h). The six patients who were measured had an increased ANH level, with a peak value as high as 277 pg/ml (normal, 25 to 77 pg/ml). ADH levels were low or normal in all but one patient, who had a marked increase in ADH and ANH. Aldosterone levels were variable. On the basis of these results, all but one patient showed evidence of CSW characterized by increased urine output, normal or increased urine sodium, low serum sodium, and increased ANH levels. The other patient had similar clinical findings consistent with CSW but also had an increase in ADH, thus giving a mixed laboratory picture of SIADH and CSW. The association of CSW to cranial vault remodeling has previously been ignored. This study should prompt reevaluation of the broad grouping of SIADH as the cause of all hyponatremic episodes in our postoperative patient population. An etiologic role has been given to ANH and to other, as yet undiscovered, central nervous system natriuretic factors. All of the patients studied required normal saline resuscitation, a treatment approach that is contrary to the usual management of SIADH. These findings should dictate a change in the postoperative care for these patients. After cranial vault remodeling, patients should prophylactically receive normal saline, rather than a more hypotonic solution, to avoid sodium balance problems.

Aldosterone↗
PubMed2001

Anaesthesia in the United Nations Military Hospital, Dili, East Timor.

An analysis of the anaesthesia caseload of the United Nations Military Hospital and its predecessors over the first 12 months of operation from September 1999 has been performed. Most patients were East Timorese civilians or Australian Military personnel. General anaesthesia using the ULCO Portable Field Anaesthesia Machine was most commonly administered.

Adult↗
PubMed2001

Thermal capsulorrhaphy for instability of the shoulder: multidirectional and posterior instabilities.

Early results of thermal capsulorrhaphy appear to be favorable and the procedure seems safe when used appropriately to enhance shoulder stability, either in isolation or combination with other arthroscopic procedures. Basic science research has shown that the capsular response to thermal energy and its effect on the mechanical properties of the tissue is dependent on both time and temperature. Additional work is needed to better understand the tissue's healing response and the time required to restore its mechanical properties. Although short-term results are encouraging, longer-term follow-up and studies cited in peer-reviewed publications are needed.

Arthroscopy↗
PubMed2000

Lip service for the stiff upper lip.

Lip augmentation procedures can restore volume and shape to the aging, thin upper lip, but some patients may develop problematic lip tightness. This stiff upper lip is manifested by a restricted smile and an adynamic central upper lip. We have had success in treating postreconstruction and postaugmentation stiff upper lip with a therapeutic device and treatment regimen. This therapy alleviated tightness and inability to smile. Also, the change in lip commissure-to-commissure distance in repose and when smiling improved after treatment.

Aged↗
PubMed2000

Growth restriction of cranial sutures in the fetal lamb causes deformational changes, not craniosynostosis.

Newborns with in utero cranial vault molding can present with severe forms of plagiocephaly. Intrauterine constraint has been proposed as one cause for craniosynostosis. The purpose of this experiment was to investigate whether rigid plate fixation across a fetal cranial suture, representing a severe form of growth restriction in utero, would lead to cranial suture fusion in a fetal lamb model. Six fetal lambs at 85 to 95 days gestation (term = 145 days) underwent laparotomy, hysterotomy, fetal coronal scalp incision, and miniplate screw fixation across the right coronal suture in utero. Two unoperated twins and four unoperated age-matched lambs were used as controls (n = 12). Animals were killed at both 4 and 8 weeks postoperatively. Fetal head analysis consisted of gross examination, photography, basilar and lateral radiographs, and three-dimensional computed tomographic scans. Cranial suture analysis consisted of imaging by computed tomographic scan (axial and sagittal cuts) and histology of experimentally plated coronal sutures, contralateral nonplated coronal sutures and twin control coronal sutures. Gross examination, radiographs, and three-dimensional computed tomographic analysis of heads with cranial suture plating showed ipsilateral forehead flattening, contralateral forehead bossing, superiorly displaced ipsilateral orbital rim, anterolateral projection of ipsilateral malar eminence, and anterior position of the ipsilateral ear point compared with the contralateral side of the same animal and normal controls. There was no change in nasal root, chin point, or predentition occlusal plane. Although analysis of the plated coronal sutures by computed tomographic scans showed diminished width or even stenosis, the histology revealed narrowed but patent experimental coronal sutures at 4 and 8 weeks. Contralateral, nonplated coronal sutures were not only patent, but widened compared with normal control sutures. This finding may have represented compensatory changes in the contralateral coronal suture caused by growth restriction at the plated suture. These data demonstrate that intrauterine growth restriction across a cranial suture caused by compression plate fixation resulted in deformational skull changes, not craniosynostosis. In addition, these data strongly support a role for in utero positional molding secondary to growth restriction in the maternal pelvis as a cause for nonsynostotic plagiocephaly seen in newborns.

Animals↗
PubMed1999

An infrared spectral match between GEMS and interstellar grains.

Infrared spectral properties of silicate grains in interplanetary dust particles (IDPs) were compared with those of astronomical silicates. The approximately 10-micrometer silicon-oxygen stretch bands of IDPs containing enstatite (MgSiO3), forsterite (Mg2SiO4), and glass with embedded metal and sulfides (GEMS) exhibit fine structure and bandwidths similar to those of solar system comets and some pre-main sequence Herbig Ae/Be stars. Some GEMS exhibit a broad, featureless silicon-oxygen stretch band similar to those observed in interstellar molecular clouds and young stellar objects. These GEMS provide a spectral match to astronomical "amorphous" silicates, one of the fundamental building blocks from which the solar system is presumed to have formed.

Cosmic Dust↗
PubMed1999

Cranial vault deformity and intracranial hypertension secondary to cephalic molding at delivery: a case and its management.

Cephalic molding at birth has been traditionally felt to be benign, resulting in only a transient and self-correcting cranial deformity. However, we report a 6-month-old infant who presented with extensive cephalic molding at birth in combination with persistent brachyturricephaly from unilateral coronal synostosis and occipital deformation. Helmet therapy over a 3-month period failed despite patient compliance and numerous adjustments. Intracranial hypertension developed, as documented by multiple occipital bony erosions on computed tomographic scan and by an elevated direct intracranial pressure reading. The cranial vault asymmetry was corrected in two surgical stages: (1) occipital bar advancement, temporoparietal bone remodeling, and midline sagittal strip compression to reduce vertical height, followed in 3 months by (2) fronto-orbital advancement and remodeling.

Birth Injuries↗
PubMed1999

Large arteriovenous malformations of the face: aesthetic results with recurrence control.

Large facial arteriovenous malformations are problematic for patients because of grotesque disfigurement, risk of rapid enlargement, and life-threatening rupture. Successful treatment of these relentless complex lesions is one of the most difficult challenges facing plastic surgeons. From a series of 300 large facial arteriovenous malformations, 85 patients were treated with embolization and excision; six of these cases (representing six separate anatomic regions: labial, auricular, eyelid, cheek, chin, and occipitoparietal) were selected for review. The purpose of this article was to look critically at the management of these six facial arteriovenous malformations, including patient presentation, angiographic procedures, surgical planning and technique, and postoperative long-term follow-up care. Lessons learned from the six representative cases provide clues for the management of large facial arteriovenous malformations and demonstrate the possibilities of recurrence and their occasionally relentless behavior. The cases show that long-term control of these lesions with acceptable aesthetic results can be achieved. The mainstay of treatment includes the following: (1) selective intra-arterial embolization with fine catheters and direct lesional embolization; (2) judicious resection and reconstruction with local or expanded tissue flaps; and (3) careful follow-up with serial examinations, duplex, and arteriography.

Adolescent↗
PubMed1999

Nasal expansion in the fetal lamb: a first step toward management of cleft nasal deformity in utero.

The cleft nasal deformity, a combination of malpositioned cartilage and tissue and postrepair scarring, is a difficult problem to correct. To harness the potential of scarless fetal wound healing, in utero repair of cleft lip and palate deformities has been studied but the fetal cleft nose deformity has not been addressed. The purpose of this study was to manipulate the fetal nasal shape in utero as a first step toward restoration of normal nasal form in cleft nasal deformities. To do this, preformed hypertonic sponges were placed into the right nostril of eight fetal lambs during the second trimester (when scarless cutaneous wound repair is known to occur). Then, the size and shape of fetal nasal structures were analyzed after selected time periods (1, 2, and 6 weeks) with measurements, routine histologic examination, and three-dimensional computed tomographic scans of the experimentally expanded noses compared with the control nonexpanded noses of the birth twins or age-matched specimens. Results showed that experimentally expanded nasal structures had markedly increased in septal length measurement, in nostril area (doubled), and in intranasal volume (more than doubled). Histology showed normal cellular elements without scarring in the tissue sections from the expanded nasal areas. In conclusion, the shape of nasal tissue can be manipulated without scarring in second-trimester fetal lambs after placement of a nasal expansion device. This study is an experimental first step toward restoring normal nasal form by repositioning alar cartilages and soft tissue during fetal cleft repair.

Animals↗