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Biomedical subjects

J L Schaffer

Publications and source records attributed to J L Schaffer.

At least 37 records · Page 2Linked to original sources
PubMed1997

The PartnerWeb Project: a component-based approach to enterprise-wide information integration and dissemination.

A component-based health information resource, delivered on an intranet and the Internet, utilizing World Wide Web (WWW) technology, has been built to meet the needs of a large integrated delivery network (IDN). Called PartnerWeb, this resource is intended to provide a variety of health care and reference information to both practitioners and consumers/patients. The initial target audience has been providers. Content management for the numerous departments, divisions, and other organizational entities within the IDN is accomplished by a distributed authoring and editing environment. Structured entry using a set of form tools into databases facilitates consistency of information presentation, while empowering designated authors and editors in the various entities to be responsible for their own materials, but not requiring them to be technically skilled. Each form tool manages an encapsulated component. The output of each component can be a dynamically generated display on WWW platforms, or an appropriate interface to other presentation environments. The PartnerWeb project lays the foundation for both an internal and external communication infrastructure for the enterprise that can facilitate information dissemination.

Computer Communication Networks↗
PubMed1996

Variable hormone responsiveness of osteoblast populations isolated at different stages of embryogenesis and its relationship to the osteogenic lineage.

A variable response to 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] hormone treatment was observed for osteoblast cell populations isolated from 12- and 17-day-old embryonic chick calvariae. The younger embryonic cell population showed 2- and 5-fold inductions of osteocalcin and osteopontin gene expression, respectively, and a 25% inhibition of collagen gene expression when treated with 1,25-(OH)2D3. In contrast, these same genes all displayed approximately 80% inhibition of their expression when the older embryonic cell populations were treated with hormone. The hormone response was related to the appearance of the vitamin D3 receptor (VDR) and the developmental state of teh two cell populations by assessing the numbers of cells that were immunologically labeled for two osteoblast lineage, stage-specific surface makers (alkaline phosphatase and SB-5, an osteocyte marker) and the VDR. Using the sequence of marker presentation, with VDR appearing first, followed by alkaline phosphatase and then SB-5, models were tested using logistic regression analysis to validate this order of marker presentation and establish that the two embryonic ages of the cell populations represent discrete stages of their lineage. This analysis indicated that 1,25-(OH)2D3 treatment progressed the 12-day-old embryo cell populations along their lineage and that the hormone promoted the appearance of its own receptor (P < 0.001) However, the appearance of the VDR does not appear to be a determinant in the variable responses of the different embryonic aged cell populations to the hormone. These data quantitatively establish the unique nature of osteoblast cell populations within their lineage progression for cells isolated from embryos of different ages, such that cell populations isolated from younger embryos are comprised of primarily presumptive or immature osteoblasts, whereas cells isolated from older embryos are comprised of mature osteoblasts. These data also demonstrate that the genomic effects of 1,25-(OH)2D3 are dependent on the developmental stage of the osteoblast lineage, and the stimulatory actions of the hormone are targeted to immature osteoblasts, whereas the effect of the hormone on mature osteoblasts is inhibitory.

Animals↗
PubMed1996

Facilitating physician referrals on the World Wide Web: representation and appropriate utilization of clinical expertise.

In highly integrated and increasingly complex health care systems, the identification and proper utilization of clinical staff expertise are key factors for efficiently delivering high quality patient care. To achieve these capabilities on an enterprise-wide scale, we have embarked on a multi-phased project to develop World Wide Web (WWW)-based physician referral capabilities for two large teaching hospitals. Currently, users may search for information concerning the education, training, board certifications, and self-designated clinical interests of staff members. Address, phone number, email address, and a photo are also presented. Our experience indicates that institutional changes are required to successfully deploy and maintain online physician referral services and that accurate and equitable representation of clinical expertise and the incorporation of referral guidelines require an incremental introduction of a carefully planned program that addresses the needs of clinicians, administrators, and health care policy-makers.

Boston↗
PubMed1995

Development of degenerative spondylosis of the lumbar spine after partial discectomy. Comparison of laminotomy, discectomy, and posterolateral discectomy.

STUDY DESIGN: The development of degenerative spondylosis after successful operative decompression of the affected nerve root was prospectively evaluated in a comparative case series of 100 patients with a herniated lumbar nucleus pulposus. OBJECTIVES: The objective of this study was to compare the relative incidence of degenerative spondyloarthrosis after successful posterior laminotomy and discectomy and posterolateral extradural discectomy for decompression of a compromised lumbar nerve root. SUMMARY OF BACKGROUND DATA: The relationship between the radiographic appearance of degenerative spondylosis and prior operative procedures has been controversial and at times contradictory. The posterior operative approach with a partial discectomy has been associated with a significant incidence of postoperative degenerative spondylosis and intraneural and perineural fibrosis, complications that may be minimized, or perhaps even eliminated, with the posterolateral evacuation of the offending intervertebral disc fragment. METHODS: Each patient had: 1) not responded favorably to nonoperative treatment, 2) a persistent radiculopathy, 3) correlative imaging studies with no preoperative spondyloarthrosis and 4) minimum 2-year follow-up. Fifty patients were treated by posterior laminotomy and discectomy and fifty were treated by a posterolateral extradural discectomy. Postoperative spondylosis was graded based on the radiographic presence or absence of osteophytes, the intervertebral disc height, the vertebral body alignment and the facet joint changes. RESULTS: At an average postoperative follow-up of 65 months, the incidence of a one grade increase in degenerative spondylosis was 80% of the laminotomy and discectomy patients as compared to 39% of the posterolateral discectomy patients. CONCLUSIONS: The increased incidence of spondyloarthrosis with the posterior approach suggests that minimally invasive posterolateral extradural procedures should be considered for the decompression of a compromised lumbar nerve root.

Diskectomy↗
PubMed1995

Mechanisms of meniscal tissue ablation by short pulse laser irradiation.

A new experimental technique was developed to study short-pulsed laser ablation of biologic tissues (human meniscus and bovine tibial bone), water, and acrylic. The experimental technique was based on interferometric monitoring of the motion of the tissue surface to measure its laser-induced expansion after irradiation. The thermoelastic expansion of these materials after laser irradiation under subablation threshold was examined to determine its role in the initiation of ablation. The experimentally observed surface expansion of cortical bone and acrylic was in agreement with theoretical predictions. The movement of meniscal tissue was similar to that shown by water. The latter 2 materials showed additional features consistent with the growth and collapse of cavitation bubbles. The exact role of cavitation in the irradiation of meniscal tissue by laser light remains unknown, but may represent a clinically important mode of tissue ablation and postirradiation trauma.

Animals↗
PubMed1994

Device for the application of a dynamic biaxially uniform and isotropic strain to a flexible cell culture membrane.

A large number of studies have demonstrated that mechanical perturbation modulates cellular metabolism; however, the systematic characterization of the molecular and cellular transduction mechanisms underlying mechanically induced metabolic modulation has been impeded, in part, by the limitations of the mechanical device. The objective of this investigation was to develop an in vitro experimental system that would provide independent control of the spatial and temporal biaxial strain distribution imposed on a flexible transparent tissue culture membrane that permits attachment, proliferation, and maintenance of the phenotypic expression of cultured embryonic osteoblasts. Such a device would permit a systematic investigation of the cellular response to specific, independently controlled parameters of mechanical deformation. Using a prototype device designed to impose a dynamic sinusoidal spatially isotropic biaxial strain profile, we confirmed experimentally that the strain was biaxially uniform and isotropic (radial = circumferential strain over the entire culture membrane) to within 14% (SD/mean) for the range of the peak strains tested (2.3-9.4%). Additionally, the uniformity was maintained at 1 Hz for at least 5 days of continuous operation. This experimental verification of the theoretically predicted isotropic strain profile suggests that the design principle is sound. Embryonic osteoblasts cultured on the flexible substrate proliferated and exhibited a temporal pattern of phenotypic expression (extracellular matrix accumulation and mineralization) comparable with that observed on polystyrene of tissue culture grade.

Animals↗
PubMed1991

Proliferation and macromolecular synthesis by rat calvarial bone cells grown in various oxygen tensions.

Perinatal rat calvarial bone cells were isolated by sequential collagenase digestion and grown in oxygen tensions ranging from 1 to 60% O2. Cell proliferation as determined by automated cell counting and DNA content was greatest in the lower oxygen tensions (less than or equal to 9% O2), whereas alkaline phosphatase activity and [35S]sulfate and [14C]proline incorporation were greatest in the higher oxygen tensions (greater than or equal to 13% O2). It is concluded that lower oxygen concentrations favor bone cell proliferation, whereas higher oxygen concentrations favor macromolecular synthesis. These findings, when related to the known pO2 of the fracture callus, suggest the following sequence of events: first, at the time of fracture an ingrowth of osteoprogenitor cells, capillary buds, and primitive mesenchymal cells occurs in the fracture site, a region of low pO2; second, a great increase in cellular proliferation accompanied by an initiation of macromolecular synthesis follows; finally, as the pO2 levels begin to increase, cellular proliferation decelerates, accompanied by an increase in macromolecular synthesis.

Alkaline Phosphatase↗
PubMed1991

Capsular impingement as a source of pain following bipolar hip arthroplasty.

Concerns regarding the extent and predictability of pain relief with bipolar hemiarthroplasty have been raised. Inconsistent clinical results have been reported, with persistent postoperative groin pain noted in some patients. A diverse number of bipolar operative techniques have been reported, but discussion of the surgical treatment of capsular tissue has usually been omitted. Although the source of postoperative pain is difficult to determine, the authors report the relief of groin pain after a capsulectomy in a patient with a preexisting bipolar hemiarthroplasty, thus offering one possible etiology.

Adult↗
PubMed1991

Percutaneous posterolateral lumbar discectomy and decompression with a 6.9-millimeter cannula. Analysis of operative failures and complications.

The operative failures and complications of percutaneous posterolateral lumbar discectomy were analyzed in 100 patients who had a herniated nucleus pulposus and were prospectively studied and treated with use of a 6.9-millimeter outer-diameter (4.9-millimeter inner-diameter) sheath and manual insertion of the instruments. Twelve operations were considered to have failed, regardless of the length of postoperative follow-up or the incidence of reinjury; eleven patients had a repeat operation at the index level, and one patient was a chronic drug-abuser. In eight of the eleven patients, subsequent laminectomy was successful. Two patients had a psoas hematoma and one had a transitory sensory and distal motor deficit; all of these complications resolved without sequelae. There were no major complications, including superficial or deep infection, and no patient had neurovascular compromise.

Adult↗
PubMed1991

Routes and incidence of communication of lumbar discs with surrounding neural structures.

Several authors have previously reported the complications resulting from contact between a diagnostic or therapeutic agent injected into an intervertebral disc and neural tissue. This study was undertaken to demonstrate the common routes by which, and frequency with which this contact occurs. Of 105 cadaveric intervertebral discs studies, 15 (14%) leaked. Of the discs that leaked, 27% demonstrated contact of injected dye with the adjacent spinal nerve. The high rate of leakage may be related to the age of the cadavers. Nonetheless, the contact between substances injected into an intervertebral disc and adjacent neural tissue during discography offers an alternate mechanism of pain reproduction in an incompetent disc. It also suggests that nontoxic agents should be used for discography and that intervertebral discs should be proved competent before chemonucleolysis.

Aged↗
PubMed1990

Students teaching students: a medical school peer tutorial programme.

A peer tutorial programme which is available to all first- and second-year medical students has been in operation at Case Western Reserve University School of Medicine since 1972. A retrospective study of the classes of 1982, 1983 and 1984 was undertaken to assess the participation levels in the tutorial programme and to compare the participation level to available performance parameters. The analysis revealed that 54% of the first-year classes and 22% of the second-year classes participated in the peer tutorial programme. X2 analysis of the data demonstrated that the relationship between participation in the tutorial programme and performance on examinations reached statistical significance. The results suggested that an open peer tutorial programme responded to the needs, both cognitive and affective, of medical students.

Education, Medical, Undergraduate↗
PubMed1989

Kienböck's disease in a patient with Crohn's enteritis treated with corticosteroids.

In a patient with Crohn's enteritis treated with oral corticosteroids simultaneous Kienböck's disease and femoral head osteonecrosis developed 2 years after the administration of corticosteroids. The patient had no history of trauma or any other risk factor known to be associated with Kienböck's disease. This case suggests that corticosteroid administration may be an additional factor in the multifactorial causes of Kienböck's disease.

Adrenal Cortex Hormones↗
PubMed1989

Percutaneous lumbar discectomy. Review of 100 patients and current practice.

In a prospective study, 100 patients with 102 herniations of the nucleus pulposus at L2-L3, L3-L4, L4-L5, and L5-S1 and unremitting radicular pain were treated by percutaneous lumbar discectomy. Ninety-three patients were available for follow-up examination. Three patients had died, and four patients could not be located for this review, but all had been followed for more than one year postoperatively and were judged to have had an excellent result at the time of the last follow-up examination. Fifty-nine patients have been followed for longer than two years postoperatively, with a maximum follow-up period of six years. Evaluations were based on modified MacNab criteria and patient interview, questionnaire, and examination. Eighty-one patients (87%) were judged to be successes, since they were pain-free and had returned to gainful employment and their preinjury activity levels. Twelve patients' operations (13%) were judged to be failures and required repeat surgical procedures at the level of the presenting pathologic condition. Three patients (not included in the follow-up group) died of unrelated causes; they had been followed for a minimum of 15 months postoperatively and were previously judged to have had an excellent result. No major complications, including superficial or deep infections, discitis, or neurovascular compromise, were encountered. Meticulous selection of patients for percutaneous lumbar discectomy is the key to success with the method.

Adult↗