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Biomedical subjects

J B Webster

Publications and source records attributed to J B Webster.

15 recordsLinked to original sources
PubMed2006

Sprouty genes are expressed in osteoblasts and inhibit fibroblast growth factor-mediated osteoblast responses.

Fibroblast growth factors (FGFs) and fibroblast growth factor receptors (FGFRs) are major regulators of skeletal growth and development. Signal transduction via FGFRs is complex and mediates proliferation, differentiation, or migration depending upon the cellular context. Members of the Spry gene family antagonize the FGFR signal transduction pathway and inhibit lung morphogenesis, angiogenesis, and chondrogenesis. We examined the expression of Spry2 in the osteoblastic MC3T3-E1 cell line. MC3T3-E1 cells express Spry2 in response to FGF1 stimulation. Treatment of MC3T3-E1 cells with FGF1 results in the expression of Spry2 in a manner consistent with an early response gene. Pharmacological inhibitors of mitogen-activated protein kinase activation inhibit FGF1-induced expression of Spry2 mRNA. Transient overexpression of Spry2 in MC3T3-E1 resulted in decreased FGF1-mediated extracellular signal-regulated kinase phosphorylation and FGF1-stimulated osteopontin promoter activity. Furthermore, we show that Spry2 interacts with Raf-1 in a glutathione-S-transferase pulldown assay and that this interaction may involve multiple sites. Finally, Spry2 expression precedes the onset of the expression of osteoblast differentiation markers in an in vitro assay of primary osteoblast differentiation. Taken together, these results indicate that Spry2 expression is an early response to stimulation by FGF1 in MC3T3-E1 cells and acts as a feedback inhibitor of FGF1-induced osteoblast responses, possibly through interaction with Raf1.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Sleep apnea in adults with traumatic brain injury: a preliminary investigation.

OBJECTIVE: To determine the occurrence and nature of sleep-related breathing disorders in adults with traumatic brain injury (TBI). DESIGN: Prospective, observational, consecutive sample enrollment of subjects admitted for rehabilitation after TBI. SETTING: Inpatient rehabilitation and subacute rehabilitation units of a tertiary care university medical system. PARTICIPANTS: Subjects (n = 28) included adults with TBI and a Rancho Los Amigos Scale level of 3 or greater who were less than 3 months postinjury and admitted for comprehensive inpatient rehabilitation. INTERVENTIONS: Overnight sleep study using portable 6-channel monitoring system. MAIN OUTCOME MEASURE: Respiratory disturbance index (RDI), which is the number of apneic and hypopneic episodes per hour of sleep. RESULTS: Evidence of sleep apnea was found in 10 of 28 (36%) subjects as measured by a RDI level of 5 or greater and in 3 of 28 (11%) subjects as measured by a RDI level of 10 or greater. This rate of sleep apnea is significantly (p =.002) higher than would be predicted based on population norms. No correlation was found between the occurrence of significant sleep apnea and measures of TBI severity or other demographic variables. Sleep-related breathing disorders were primarily central though obstructive apneas were also noted. CONCLUSION: In this preliminary investigation, sleep-related breathing disorders as defined by a respiratory disturbance index of 5 or greater appears to be common in adult subjects with TBI.

Adult↗
PubMed2001

Acquired limb deficiencies. 3. Prosthetic components, prescriptions, and indications.

UNLABELLED: This self-directed learning module highlights indications for prosthetic components and prescription formulation for adults with acquired limb deficiency. It is part of the chapter on acquired limb deficiencies in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. Advantages and disadvantages of specific components of upper and lower limb prostheses are discussed, and a sample prescription sheet for upper limb devices is included. Recent innovations in terminal devices for upper limb prostheses are reviewed. Special considerations for the adult with acquired multilimb deficiency are also examined. OVERALL ARTICLE OBJECTIVE: To describe indications for prosthetic components and prescription formulation for adults with acquired limb deficiency.

Adult↗
PubMed2001

Sports and recreation for persons with limb deficiency.

UNLABELLED: Opportunities for persons with limb deficiency to participate in sport and recreational activities have increased dramatically over the past 20 years. Various factors have contributed to this phenomenon, including an increased public interest in sports and fitness as well as improvements in disability awareness. An even more essential element has been a consumer-driven demand for advances in prosthetic technology and design. Whether the activity is a music performance, a friendly round of golf, or a high-level track-and-field competition, the benefits of participation in sports and recreation are numerous both at the individual and at the societal level. This article provides an overview of the development and scope of sport and recreational opportunities available to persons with limb deficiency. In addition, specific prosthetic considerations for several common sport and recreational activities are presented in a case-discussion format. OVERALL ARTICLE OBJECTIVE: To review the development and scope of sport and recreational opportunities available to persons with limb deficiency.

Adolescent↗
PubMed1997

Primary adrenal insufficiency following traumatic brain injury: a case report and review of the literature.

Primary adrenal insufficiency (PAI) is a relatively rare but serious condition that can lead to signs and symptoms ranging from mild generalized weakness and fatigue to fulminant shock and death. We present the case of a previously healthy 31-year-old man who developed PAI while undergoing rehabilitation after a severe traumatic brain injury (TBI). The patient suffered a TBI with comminuted skull fractures, bifrontal confusions, and bilateral epidural hematomas in a jet-ski accident. Acute hospitalization was prolonged by several medical complications, and the patient was admitted for subacute rehabilitation 1 month after his injury with cognitive deficits, persistent agitation, confusion, generalized weakness, and poor endurance for therapy. His weakness, fatigue, and orthostasis did not improve with attempts at gradual remobilization. The patient also had persistent anorexia, nausea, and hyponatremia despite various treatment regimens. Endocrinology workup showed normal anterior pituitary function but an abnormal response to adrenocorticotropic hormone (ACTH) stimulation, leading to the diagnosis of PAI. The patient was treated with prednisone and fludrocortisone, which resulted in improvement in clinical symptoms followed by rapid gains in all functional areas. No previous descriptions of PAI following head injury were found in the medical literature. It is important for physiatrists to be aware of this entity because symptoms of adrenal insufficiency can be similar to those commonly seen with TBI alone. PAI may also be confused with other endocrine disorders more frequently seen after TBI such as the syndrome of inappropriate antidiuretic hormone secretion. Recognition and appropriate management of adrenal insufficiency can lead to significant clinical and functional gains.

Adrenal Insufficiency↗
PubMed1983

Naturalistic studies of human light exposure.

For 24 h, 10 volunteers wore an apparatus that recorded their exposure to light at eye level and at the wrist. Activity was also recorded from the head, both wrists, and an ankle. Most of the subjects were exposed to daylight illumination intensities for only brief and scattered episodes during the 24 h. Some experienced the brightest illumination in the morning and others in the evening. Illuminations at eye level and at the wrist were correlated 0.76, while eye-level illumination was correlated 0.25, 0.44, 0.39, and 0.44 with head, wrists, and ankle activity, respectively. Because human biologic rhythms are probably well synchronized only by illumination approaching daylight intensities, inadequate illumination could be a source of sleep disturbance, chronobiologic disorders, or depression.

Adult↗
PubMed1982

An activity-based sleep monitor system for ambulatory use.

Wrist activity measured with a piezoceramic transducer was digitized and analyzed together with subjects' sleep/wake status to derive an optimal method for automatic computer sleep/wake scoring. Several algorithms for quantifying periods of activity were considered, and an algorithm that summed changes in activity level over a 2-s interval was found most sensitive. A computer program for scoring sleep/wake from the resulting digital activity records was then developed, and parameters derived by comparison with subjects' sleep/wake status as determined by EEG. EEG and activity sleep/wake scores agreed 94.46% of the time. A further prospective test of the automatic scoring system with new data yielded agreement of 96.02%. Finally, the data collection and recording functions were implemented in a wearable microprocessor-based digital activity monitor. The automatic scoring program was adjusted to use activity data collected by this monitor, and agreed 93.88% with EEG scoring. A prospective test with new data agreed 93.04% with EEG. Automatic scoring of activity data for sleep/wake is not only fast and accurate, but allows sleep to be monitored in non-laboratory situations. In addition, the score is objective and reliable, and free of scorer bias and drift.

Computers↗
PubMed1981

Effects of changing compatibility relationships on reaction time to the first stimulus in a double-stimulation task.

This study investigated the effects of manipulating the response requirement to the second stimulus (S2) on reaction time (RT) to the first stimulus (S1) in a double-stimulation choice RT task. Forty subjects responded to the 100 msec presentation of a left or right light by pressing the key on the same or opposite side as the light. Treatment conditions included a single-stimulation control (no S2 presented), and two double-stimulation conditions each requiring two responses (R1 and R2) in close succession, in one of these latter conditions, the rule governing R2 was the same as that governing R1 while, in the other, the rule governing R2 changed. Results showed the typical double-stimulation effect; i.e., increased latency of R1 when it was followed by S2 - R2. More importantly, R1 latency was increased further when the rules governing R1 and R2 were different. Results are discussed in terms of divided preparation capacity as well as other theories of the psychological refractory period.

Journal Article↗