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Biomedical subjects

J T Watson

Publications and source records attributed to J T Watson.

173 records · Page 10Linked to original sources
PubMedDate not supplied

Unreamed retrograde intramedullary nailing of fractures of the femoral shaft.

OBJECTIVE: To evaluate the efficacy of unreamed retrograde intramedullary (IM) nailing of fractures of the femoral shaft in a second series of patients using modifications suggested from our initial study. DESIGN: Prospective. SETTING: Level I trauma center. METHODS: Based on the findings of a previous study, we began a clinical series incorporating changes consisting of (a) inclusion of any patient with a femoral shaft fracture amenable to IM nailing (i.e., closed physes), (b) primary use of a split patellar tendon intercondylar distal femoral entry portal, and (c) the use of a full-length femoral implant having variable size availability and dynamization capability. Over a twelve-month period, thirty-four patients with thirty-five femoral shaft fractures were treated. The protocol called for planned dynamization in statically locked stable fractures and unstable fractures showing minimal healing at six to twelve weeks. Functional outcome was assessed by using the Knee Society clinical rating system. RESULTS: Incorporating the concepts of canal fill and early dynamization, there were only two nonunions (6 percent) in this series as compared with 14 percent in the previously reported series with an overall shorter time to union (12.6 versus 15 weeks). There were no infections or malunions. Postoperative complaints of knee pain were minimal (knee score average: 98 points) and knee function was excellent (knee score average: 97 points). CONCLUSIONS: Although not advocated as a replacement for other techniques, unreamed retrograde nailing is presented as a safe and beneficial fracture fixation method that should be added to the orthopaedic surgeon's treatment armamentarium. The operative technique is quick and simple, and blood loss is minimal. Early nail dynamization and early weight-bearing are important in minimizing the risk of nonunion.

Adolescent↗
PubMedDate not supplied

Composition-selective detection of polychlorinated biphenyls (PCBs) by oxygen-chlorine exchange reaction in a tandem mass spectrometer (MS/MS).

The exchange reaction of chlorine by oxygen with polychlorinated biphenyl (PCB) anions was explored as a method for composition-selective detection of PCB congeners in a gas chromatograph/tandem mass spectrometer (GC/MS/MS) experiment. The odd-electron molecular anions of PCBs react with molecular oxygen introduced into the collision cell of a triple-quadrupole mass spectrometer to form a product ion that has 19 mass units less (35Cl - 16O) than the precursor. The even-electron anions which also form in the source do not react when allowed to pass through the precursor analyzer. Multiple reaction monitoring allows the generation of separate chromatograms for each different composition from tetrachloro through nonochloro PCB. Most coelutants are resolved in this way. Response factors for the 12 coplanar congeners that exhibit dioxin-like toxicity relative to octachloronaphthalene vary from 1.6 to 580. Results of the analysis of an Aroclor 1242 sample for the coplanar congeners compare well with previously determined values.

Anions↗
PubMedDate not supplied

Retrograde nailing of the femoral shaft.

Retrograde intramedullary nailing of fractures of the femoral shaft with use of a distal intercondylar intra-articular entry portal is a relatively new surgical technique. This method of nailing represents a modification of the previously described procedure in which an extra-articular entry portal in the medial femoral condyle was used. The earlier procedure was plagued by technical difficulties, which limited its use; these problems were mainly related to the fact that the entry portal was not in line with the intramedullary canal, as well as to the fact that purpose-specific implants and instrumentation were not available. Modification of this technique, by using the intercondylar entry portal and a nail designed for retrograde insertion, has proved very effective in clinical studies. There have been theoretical concerns regarding postoperative knee function and intraoperative injury to important anatomic structures, such as branches of the femoral nerve; however, laboratory and clinical findings have dispelled many of these concerns and have provided firm support for continued use of the technique. Nonetheless, further study is required to delineate the long-term outcome of knee joint function. Current indications for use of this technique include multisystem injuries, multiple fractures (including ipsilateral lower-limb combination injuries), ipsilateral vascular injuries, periprosthetic fractures, and morbid obesity.

Equipment Design↗
PubMedDate not supplied

A major pathway of mephenytoin metabolism in man. Aromatic hydroxylation to p-hydroxymephenytoin.

A major metabolite of the antiepileptic drug mephenytoin (3-methyl-5-ethyl-5-phenylhydantoin) has been identified in urine after a single oral dose of 100 mg of mephenytoin in man. Using chemical synthesis, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy, we established its chemical structure as 3-methyl-5-ethyl-5-(4-hydroxyphenyl)hydantoin (4-OH-M) which is a product of aromatic hydroxylation of mephenytoin in man. Quantitative determinations of 4-OH-M in urine of 10 volunteers showed that 43 +/- 7% (SD) of a single oral dose of 100 mg of mephenytoin were eliminated as the glucuronide of this metabolite. Urinary elimination of the demethylated metabolite, 5-ethyl-5-phenylhydantoin (Nirvanol), was low (1% of the dose per 24 hr) emphasizing the importance of 4-OH-M as the major metabolite after a single oral dose of mephenytoin. Other products of mephenytoin hydroxylation (2-OH-M, E-OH-M, or aliphatically hydroxylated 2-OH-ethyl-M) were not detectable under the conditions selected (less than 1 mumol/24 hr).

Adult↗
PubMedDate not supplied

Evaluation of an implantable ventricular assist system for humans with chronic refractory heart failure. Study overview. LVAS Study Group. Left Ventricular Assist System.

In this summary, the authors provide the background of and proposed protocol for a clinical evaluation of the safety and efficacy of the Novacor N120 Left Ventricular Assist System, sponsored by the National Heart, Lung, and Blood Institute. Although the clinical trial was never carried out, the protocol developed for this trial may be useful to other investigators considering a clinical trial of a circulatory support device. The protocol is summarized here and in five more detailed articles in this issue.

Clinical Protocols↗
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Evaluation of an implantable ventricular assist system for humans with chronic refractory heart failure. Measuring quality of life.

The development of a multidimensional quality of life protocol to be used in a clinical trial of an LVAS was presented. The complexity of the new LVAS technology being evaluated added a unique dimension for HQL assessment. The rationale and procedures used in developing this protocol were described. Although we have elucidated the development of a protocol for a specific clinical trial, the principles and procedures employed are widely applicable. To summarize, these procedures are as follows: 1. Determine what quality of life domains are important to measure. This decision should be based upon the domains expected to be affected by treatment, those expected to change as a result of the natural course of the disease or condition, and those that may be affected by changes in the primary domains. 2. Once the domains are selected, identify specific measures for these domains. Where possible, the measures chosen should be standardized, well validated, and appropriate to the study population. Instrument length and mode of administration are additional considerations. 3. Consider any unique aspects of the study population or intervention and develop specific questions to address them. 4. Identify and measure important variables that may moderate or influence quality of life. 5. Test the protocol on an appropriate population for length, flow, and ease of administration. Copies of the complete HQL protocol are available by writing to: Dr. Nancy Avis, New England Research Institute, 9 Galen Street, Watertown, MA 02172.

Clinical Protocols↗
PubMedDate not supplied

Food and drug administration guidance sections. A new paradigm for medical devices. Committee for Clinical Review. FDA.

The data submitted for Food and Drug Administration (FDA) review of medical devices are often not approved because of poor study design. This article proposes a new approach for developing FDA study design guidance through panels of colleagues from the academic, federal, and private sectors. This piece focuses discussion and thought on Guidance Sections, similar to Study Sections of the National Institutes of Health, to serve as common ground for the continual upgrading of guidance documents through peer review and leading edge scientific and clinical judgement.

Biocompatible Materials↗