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Biomedical subjects

J L Schaffer

Publications and source records attributed to J L Schaffer.

13 recordsLinked to original sources
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↗
PubMed1988

Annular protrusion: pathophysiology and roentgenographic appearance.

The degenerative changes of the lumbar spine in 100 patients with symptomatic low-back pain were reviewed using plain roentgenograms and computed tomographic scans in order to determine the relationship between degeneration and annular protrusion. Additionally, the lumbar spinal units of 25 fresh cadavers were roentgenographed, injected with a mixture of methylene blue and renografin-60, dissected, and studied. The state of degeneration of each of the intervertebral units of both groups was graded on a four-point scale based on the roentgenographic presence or absence of osteophytes and facet joint changes, and the intervertebral disc height. The degree of annular protrusion was measured by dividing the anteroposterior diameter of the intervertebral disc by the anteroposterior diameter of the vertebral plate as determined on the radiographic studies. In the clinical group, 39 intervertebral discs having Grade II and III degeneration exhibited a statistically higher annular/vertebral diameter ratio (A/V index) of 1.30 as compared to the normal invertebral discs, with an A/V index of 1.12 (P less than 0.001). The dissection of the disc spaces of the cadavers with radiographic evidence of disc space narrowing and marginal osteophytosis, Grade II and III degeneration, displayed significant interruption and tearing of the annular fibers and peripheral migration of collagenized nuclear fragments. In both the clinical and pathologic groups, there was a direct correlation between the size of the annular bulge, as indicated in the A/V index, and the degree of narrowing of the disc space. Therefore, this study indicated that annular protrusion is an intricate part of the degeneration process.

Adult↗