Biomedical subjects
Publications and source records attributed to W C Kim.
Locked-in syndrome due to midbrain infarct is very rare. This report describes a patient with locked-in syndrome whose magnetic resonance images showed bilateral infarcts in the cerebral peduncle. Cerebral angiography disclosed bilateral irregular thrombotic narrowing of the vertebral and proximal basilar arteries with rostral basilar artery occlusion, a previously unreported findings.
Recurrent zoster myelitis is quite rare. We present a previously healthy 27-year-old woman who developed recurrent attacks of myelopathy shortly after the characteristic skin rashes of herpes zoster. Magnetic resonance imaging studies demonstrated each lesion in the spinal cord at the same segments as the skin lesions. She had two attacks at opposite sites at the same spinal cord level and complete recovery after being treated with intravenous acyclovir. We suspect that direct invasion of varicella zoster virus was the cause of recurrent myelopathy in our patient.
A 34-year-old man presented with a 30-year history of spasmodic dysphonia. He developed a speech disturbance 1 month after a closed head injury due to a fall. Sighing, coughing, and crying were normal. He had a tremor of the right hand when he drew a vertical line. His out-stretched right hand had a minimal dystonic posture with occasional jerks of the fingers. T1-weighted axial brain MRI study showed a low signal intensity lesion at the putamen; coronal and axial T2-weighted MRI brain scans showed a high and low signal intensity lesion confined to the middle part of the ventrolateral putamen. Damage to the ventrolateral putamen may have caused abnormal voluntary control of the laryngeal muscles.
Patellofemoral contact pressures resulting from fixed rotational deformities of the femur were studied in human cadaver knees. The increase in the degree of fixed rotational deformities of the femur results in a nonlinear increase in patellofemoral contact pressures on the contralateral facets of the patella (i.e., external rotational deformity resulted in a contact pressure increase on the medial facet, and internal rotational deformity resulted in a contact pressure increase on the lateral facet of the patella). With the initial isometric tension of 200 N in the quadriceps tendon for 30 degrees, 60 degrees, 90 degrees, and 120 degrees knee flexion, the peak contact pressure showed no significant differences between the medial and lateral facets of the patella in its anatomic position. At 20 degrees of rotational deformity of the femur, only a slight increase was noted for the tension in the quadriceps tendon and the patellofemoral contact pressures on the contralateral facets of the patella. However, at 30 degrees rotational deformity of the femur, both the external and internal rotational deformity of the femur showed a significant increase in the tension of the quadriceps tendon and the patellofemoral contact pressures on contralateral facets of the patella. The greatest increase in patellofemoral contact pressures was observed at 30 degrees and 60 degrees knee flexion for both the external and internal rotational deformity of the femur. The external rotational deformity of the femur for all knee flexion angles showed significantly higher peak patellofemoral contact pressure increases on the medial facet of the patella as compared with the lateral patellofemoral contact pressure increase resulting from internal rotational deformity of the femur.
Paragonimus westermani is a lung fluke of humans that is usually found in the lungs but may be found elsewhere in many unusual locations. A case of pelvic paragonimiasis was found incidentally by surgical intervention of inflammatory disease and myoma uteri. She was a 51-year-old Korean woman complaining of lower abdominal pain and intermittent vaginal spotting. Numerous Paragonimus ova were observed in the resected omentum in the pelvis after total abdominal hysterectomy. It is suggested that pelvic paragonimiasis may be one of causative agents of pelvic inflammatory disease.
Beta-adrenergic receptor density on T cells from healthy humans is greatest on suppressor cells (CD8+, CD28-) and the effect of catecholamines, secreted by the sympathetic nervous system, predominates on this subset. The sympathetic skin response, a measure of sympathetic nervous system function, is absent in most patients with chronic progressive multiple sclerosis (MS). We measured beta-adrenergic receptor density on suppressor cells, cytotoxic cells, and monocytes from patients with chronic progressive MS and healthy control subjects. Control receptor density on suppressor cells was 2.8 +/- 0.3 fmol/10(6) cells versus a density of 5.1 +/- 0.7 fmol/10(6) cells for patients. Cytotoxic cell (CD8+, CD28+) receptor density was 1.4 +/- 0.4 fmol/10(6) cells in control subjects and 0.9 +/- 0.3 fmol/10(6) cells in the patients. Monocytes displayed beta-adrenergic receptor densities of 2.6 +/- 0.4 fmol/10(6) cells in normal individuals and 2.7 +/- 0.4 fmol/10(6) cells in the patient group. CD8 lymphocyte beta-adrenergic receptor densities in patients with relapsing-remitting and those with stable MS were not different from control values, yet were significantly less than the values for patients with chronic progressive MS. We find that mononuclear cells from healthy control subjects and patients with chronic progressive MS proliferate in response to 200 units/ml of recombinant human interleukin-2 (IL-2) similarly. However, IL-2 treatment increased beta-adrenergic receptor density on normal mononuclear cells, but failed to increase it on mononuclear cells from patients with chronic progressive MS.(ABSTRACT TRUNCATED AT 250 WORDS)
Early and high failure rates for conventional hip replacements in young and active patients are well documented. The hypothesis tested in this study is total hip articular replacement by internal eccentric shells (THARIES) resurfacing hip arthroplasty is a sufficiently durable alternative to conventional total hips in patients younger than 40 years old. Survivorship analysis techniques were applied to 106 THARIES and 98 conventional hip replacements. The primary outcome variable investigated was time to failure, as measured by the need for revision of the prosthesis in the absence of sepsis. Other definitions of prosthesis failure were also investigated. Analysis revealed that even within this young, high-risk population there were subpopulations with different risks for failure. The lowest risk patients comprised all rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA) patients, regardless of age. The intermediate risk patients comprised all non-RA, non-JRA patients older than 30 years of age and the highest-risk patients were all non-RA, non-JRA patients younger than 30 years of age. A comparison of THARIES and conventional prostheses within each of these three subpopulations revealed similar patterns of failure over time, with the conventional total hip replacement having significantly better hip function than the THARIES group only in the highest-risk population, when using a failure definition of revision surgery for aseptic loosening. A broader and more important conclusion was that all acrylic-fixed implants, THARIES or THRs are predicted to undergo early mechanical loosenings in younger-than-30, non-RA, non-JRA patients. In patients younger than 30 years age acrylic fixation of THA is inadvisable.
Long-term experimental data support the hypothesis that biologic bone ingrowth into porous surfaces in a hip-resurfacing model is a viable alternative to stem-type porous implants. Ingrowth of bone was demonstrated in long-term canine arthroplasty. The components were well fixed and stable at the time of sacrifice, although ingrowth occurred to varying degrees. The ingrowth and quality of remodeling was influenced by stress. Dislocations were overcome by a change in surgical technique. Loosening and neck fractures were associated with insufficient stability at operation or to component impingement (prevented by modifications of design). The formation of metal debris-filled cysts is a concern and appeared to be associated with the poor quality of porous sintering and possibly abrasion. The effects of increased surface area of the porous components such as increased corrosion products on biologic compatibility are still not well defined and require further research and longer follow-up examination.
Bone ingrowth in the porous canine implants does occur; the early clinical results are indeed encouraging and justify further investigation. The quality of ingrowth as measured by depth and extent in the dog was stress-related. Remodelling was superior in the more compliant or elastic acetabular components without an interposed metal shell. No human specimens have been retrieved thus far, but we are encouraged because the results in the canine model with acrylic-fixed implants were comparable to the results we subsequently observed in human THARIES implantation. Those were initially excellent, but with time radiolucencies increased and loosening occurred. The quality of the canine biologic ingrowth suggests optimism for secure and durable fixation. Our patients have continued to improve through the follow-up period. There has not been a single case in which a qualitative increase in pain occurred over the cemented versions after operation. The technical problems of the surgical procedure have been overcome, but it must be performed precisely to achieve the initial inherent stability to assist in biologic ingrowth. The operative procedures in this series have been performed by or under the direct supervision of the senior author. As our competence has grown, we have applied the procedure to younger patients and those who have bone stock deficiency. One of the major advantages of the biologic ingrowth systems is the facility to graft cysts and defects. For humans, the current chamfered cylinder is an extremely bonestock-conservative procedure when combined with reaming of the femoral head to the neck size. Although space is limited in resurfacing, we have been able to achieve a minimum 4-mm bearing thickness of polyethylene. We believe that the compliant mesh chamfered cylinder system provides excellent stability. However, the hemispheric component, although technically more difficult to seat and fix, has definite applications in bonestock deficiency and with further refinement will be useful in primary replacements as well. Nevertheless, because of the uncertain future of any type of implant, especially new, we have encouraged the patients to follow a careful postoperative management program and refrain from heavy activity during the first year. Many are active and some are now participating in athletics, although this is certain to shorten the life of these implants just as was observed in acrylic-fixed devices. The biologic problems of interface corrosion, migration, and metal ion transfer indicate that these implants must be followed for longer periods. Therefore it seems unwise to extend this technology to a wide clinical use at this time.
An edited summary of an Interdepartmental Conference arranged by the Department of Medicine, UCLA School of Medicine, Los Angeles. William M. Pardridge, MD, Associate Professor of Medicine, is Director of Conferences.
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We studied the results in thirty patients who had grafting of an ununited fracture of the carpal scaphoid bone. Psychiatric evaluations revealed that the thirteen patients who had a non-union of the initial scaphoid bone graft had significant psychiatric problems, whereas the seventeen patients in whom the non-union had healed after initial bone-grafting of the scaphoid did not have psychiatric abnormalities. Technically successful surgical revisions in the first group of patients did not result in significant clinical improvement. We concluded that most failures of the bone grafts were related to non-compliance on the part of the patient and that some of the operations could have been avoided if the underlying psychiatric problems had been recognized preoperatively.
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Explore the source record for details and available documents.
Unlike the traditional factors of production--land, labor, and capital--knowledge is a resource that can't be forced out of people. But creating and sharing knowledge is essential to fostering innovation, the key challenge of the knowledge-based economy. To create a climate in which employees volunteer their creativity and expertise, managers need to look beyond the traditional tools at their disposal. They need to build trust. The authors have studied the links between trust, idea sharing, and corporate performance for more than a decade. They have explored the question of why managers of local subsidiaries so often fail to share information with executives at headquarters. They have studied the dynamics of idea sharing in product development teams, joint ventures, supplier partnerships, and corporate transformations. They offer an explanation for why people resist change even when it would benefit them directly. In every case, the decisive factor was what the authors call fair process--fairness in the way a company makes and executes decisions. The elements of fair process are simple: Engage people's input in decisions that directly affect them. Explain why decisions are made the way they are. Make clear what will be expected of employees after the changes are made. Fair process may sound like a soft issue, but it is crucial to building trust and unlocking ideas. Without it, people are apt to withhold their full cooperation and their creativity. The results are costly: ideas that never see daylight and initiatives that are never seized.
Why are some companies able to sustain high growth in revenues and profits--and others are not? To answer that question, the authors, both of INSEAD, spent five years studying more than 30 companies around the world. They found that the difference between the high-growth companies and their less successful competitors was in each group's assumptions about strategy. Managers of the less successful companies followed conventional strategic logic. Managers of the high-growth companies followed what the authors call the logic of value innovation. Conventional strategic logic and value innovation differ along the basic dimensions of strategy. Many companies take their industry's conditions as given; value innovators don't. Many companies let competitors set the parameters of their strategic thinking; value innovators do not use rivals as benchmarks. Rather than focus on the differences among customers, value innovators look for what customers value in common. Rather than view opportunities through the lens of existing assets and capabilities, value innovators ask, What if we start anew? The authors tell the story of the French hotelier Accor, which discarded the notion of what a hotel is supposed to look like in order to offer what most customers want: a good night's sleep at a low price. And Virgin Atlantic challenged industry conventions by eliminating first-class service and channeling savings into innovations for business-class passengers. Those companies didn't set out to build advantages over the competition, but they ended up achieving the greatest competitive advantages.
Most companies focus on matching and beating their rivals. As a result, their strategies tend to take on similar dimensions. What ensues is head-to-head competition based largely on incremental improvements in cost, quality, or both. The authors have studied how innovative companies break free from the competitive pack by staking out fundamentally new market space--that is, by creating products or services for which there are no direct competitors. This path to value innovation requires a different competitive mind-set and a systematic way of looking for opportunities. Instead of looking within the conventional boundaries that define how an industry competes, managers can look methodically across them. By so doing, they can find unoccupied territory that represents real value innovation. Rather than looking at competitors within their own industry, for example, managers can ask why customers make the trade-off between substitute products or services. Home Depot, for example, looked across the substitutes serving home improvement needs. Intuit looked across the substitutes available to individuals managing their personal finances. In both cases, powerful insights were derived from looking at familiar data from a new perspective. Similar insights can be gleaned by looking across strategic groups within an industry; across buyer groups; across complementary product and service offerings; across the functional-emotional orientation of an industry; and even across time. To help readers explore new market space systematically, the authors developed a tool, the value curve, that can be used to represent visually a range of value propositions.
Identifying which business ideas have real commercial potential is fraught with uncertainty, and even the most admired companies have stumbled. It's not as if they don't know what the challenges of innovation are. A new product has to offer customers exceptional utility at an attractive price, and the company must be able to deliver it at a tidy profit. But the uncertainties surrounding innovation are so great that even the most insightful managers have a hard time evaluating the commercial readiness of new business ideas. In this article, W. Chan Kim and Renée Mauborgne introduce three tools that managers can use to help strip away some of that uncertainty. The first tool, "the buyer utility map," indicates how likely it is that customers will be attracted to a new business idea. The second, "the price corridor of the mass," identifies what price will unlock the greatest number of customers. And the third tool, "the business model guide," offers a framework for figuring out whether and how a company can profitably deliver the new idea at the targeted price. Applying the tools, though, is not the end of the story. Many innovations have to overcome adoption hurdles--strong resistance from stakeholders inside and outside the company. Often overlooked in the planning process, adoption hurdles can make or break the commercial viability of even the most powerful new ideas. The authors conclude by discussing how managers can head off negative reactions from stakeholders.