Search PubMed⌕ Search

Biomedical subjects

D L Johnson

Publications and source records attributed to D L Johnson.

At least 379 records · Page 21Linked to original sources
PubMedDate not supplied

Preparing children for visiting parents in the adult ICU.

The issue of pediatric visitation in the adult ICU is a controversial one that often evokes strong opinions from critical care nurses. This author describes age-related preparation strategies and nursing actions which are successful in providing a positive experience for the child, parent, and nurse.

Adaptation, Psychological↗
PubMedDate not supplied

Silica-containing urinary calculi in dogs (1981-1993).

Silica-containing urinary calculi obtained from 773 dogs and submitted by veterinarians throughout the United States were analyzed by quantitative crystallographic analysis to determine mineral composition. Specimens were composed of either multiple mineral layers (535 specimens) or 1 mineral layer (238 specimens). Most multiple-layer calculi were composed of 80% or greater silica (300 of 535, 56%) or 20% to 79% silica (184 of 535, 34%) in any mineral layer. Most 1-layer calculi were composed of 100% silica (212 of 238, 89%). Most dogs forming silica-containing calculi were of male gender (679 of 773, 88%). Bacterial cultures of calculus or urine or both were performed on 49% (376 of 773) of the specimens, and bacterial growth was obtained from 37% (139 of 376) of samples cultured. The prevalence of calculus-associated urinary tract infection was 35% (113 of 321) in males and 47% (26 of 55) in females. The gender prevalence for infection with Staphylococcus species was 16% (51 of 321) in males and 33% (18 of 55) in females. The breed and gender of dogs that formed calculi (silica population) were compared with the hospital population (Veterinary Medical Teaching Hospital [VMTH] population) and with a population of calculus-forming dogs (Stonelab population) to determine risk factors for silica calculus formation. For all breeds compared, the ratio of males to females was higher in the silica population. The German Shepherd Dog and Old English Sheepdog were significantly overrepresented when the silica population was compared with either the VMTH population or the Stonelab population. We conclude that male German Shepherd Dogs and Old English Sheepdogs are at increased risk for formation of silica-containing urinary calculi.

Animals↗
PubMedDate not supplied

Renal calculi in dogs and cats: prevalence, mineral type, breed, age, and gender interrelationships (1981-1993).

Three hundred seventeen specimens of urinary calculi of renal origin from 214 female dogs and 103 male dogs, and 71 specimens of urinary calculi of renal origin from 38 female cats and 33 male cats were submitted for mineral analysis between July 1, 1981, and December 31, 1993. Among dogs, 45 breeds were affected with renal calculi. Thirty-three breeds and a crossbred group were represented among females, but 8 breeds and the crossbred group accounted for 81% of the total. Among male dogs, 30 breeds and a crossbred group were represented, but 7 breeds and the crossbred group accounted for 69% of the total. Among cats, 10 breeds and a crossbred group were represented. Dogs and cats with renal calculi were older than those of 2 comparison population groups. More than one-half of the renal calculi in both dogs and cats were from the 1st known episode of urolithiasis. The risk of formation of renal calculi was found to be higher for cats than for dogs, when compared to other stone-forming cats and dogs (approximately 4.95 per 100 stone-forming cats and 2.88 per 100 stone-forming dogs). Among dogs, breeds at highest risk of developing renal calculi were Miniature Schnauzers, Shih Tzus, Lhasa Aposos, Yorkshire Terriers, and female Pugs. Also at high risk were male Dalmatians and male Basset Hounds. Among small dogs, females generally were at higher risk of developing renal calculi than were males. Regardless of size, terrier breed males generally were at higher risk of developing renal calculi. Breeds of dogs at low risk for development of renal calculi included crossbreds. German Shepherd Dogs, Labrador Retrievers, Golden Retrievers, and female Dachshunds. When only 1 kidney was involved, the risk of left renal calculus was greatest for both dogs and cats, but bilateral renal involvement was relatively common in both species (19% and 9%, respectively). Among dogs, specimens composed of 1 mineral substance (e.g., struvite) occurred more often in males (58.3%) than in females (37.9%). Female dogs formed renal calculi containing struvite or oxalate more often than did males; males formed calculi containing urate more often than did females. Calculi containing oxalate, apatite, or some combination of these minerals predominated among cats; only 1 specimen from 38 female cats and only 4 specimens from 33 male cats contained neither oxalate nor apatite. Crossbred cats were significantly less likely to have renal calculi than were other breeds. A single renal calculus specimen was identified in several uncommon breeds including Tonkinese and Birman cats, and Affenpinscher, Clumber Spaniel, English Shepherd, and Field Spaniel dogs. No significant differences were observed between male and female dogs or between male and female cats with regard to mineral type of the specimen and the presence of urinary tract infection.

Age Distribution↗
PubMedDate not supplied

Toward the prediction of neurological injury from tethered spinal cord: investigation of cord motion with magnetic resonance.

Experience with spinal dysraphism has taught that spinal cord tethering will eventually produce neurological deficit. The primary diagnostic and monitoring tool, magnetic resonance (MR) scanning, almost always produces images consistent with cord tethering, even in asymptomatic or improved, previously operated patients. This presents a problem in selecting appropriate candidates for prophylactic intervention. Ideally, a method of monitoring should predict functional deterioration. Real-time ultrasonography, electrophysiological tests, and phase-motion MR studies could potentially be adapted for this purpose. The authors have evaluated the latter technique in both symptomatic and asymptomatic dysraphic patients with tethering. Studies of cervical cord motion show a clear separation between results in patients with cord expansion from hydromyelia and those with pure tethering. Symptomatic patients with progressive deficit or pain have limited cervical cord motion which improves after surgical untethering. MR studies of cord motion have definite promise in the prediction of deficit from spinal cord tethering and should be further evaluated in comparison with ultrasound and electrophysiologic methods.

Adolescent↗
PubMedDate not supplied

Dilemmas in the management of childhood brain tumors: brainstem gliomas.

Brainstem glioma is a malignant childhood brain tumor for which the 'best' treatment approach has not been defined. Many issues concerning the management of these lesions require clarification, including the following. (1) Can patients be reliably separated into risk groups? (2) Is surgery indicated; if so, for which patients? (3) How effective are new radiotherapy regimens? (4) What other forms of treatment are available? This article will attempt to address these management issues.

Brain Neoplasms↗
PubMedDate not supplied

The effect of a geographic lateral bone bruise on knee inflammation after acute anterior cruciate ligament rupture.

We prospectively evaluated 40 patients who had knee inflammation after isolated anterior cruciate ligament rupture with or without an associated "geographic" bone bruise/subchondral fracture of the lateral femoral condyle. All patients with acute ruptures documented by magnetic resonance imaging within 1 week of injury were evaluated for a geographic bone bruise/subchondral fracture of the lateral femoral condyle. Two groups of 20 patients each (bone bruise versus no bone bruise) were then enrolled. Variables measured at 1, 2, 3, and 4 weeks after injury included pain, range of motion, effusion, and number of days with an antalgic gait. Patients with a bone bruise had increased size and duration of effusion, increased number of days required to nonantalgic gait without external aids, increased days to achieve normal range of motion, and increased pain scores at measured time intervals. This study confirms results of previous clinical and histologic studies showing an associated articular cartilage lesion, otherwise known as bone bruise/subchondral fracture, is clinically significant. There appears to be an association between a geographic bone bruise and increased disability in patients with acute anterior cruciate ligament ruptures. Patients with a geographic bone bruise may require longer to reach normal homeostasis (range of motion, pain, neuromuscular control) before undergoing anterior cruciate ligament reconstruction.

Anterior Cruciate Ligament Injuries↗
PubMedDate not supplied

Interference screw fixation strength of a quadrupled hamstring tendon graft is directly related to bone mineral density and insertion torque.

The purpose of this study was to determine whether bone mineral density of the host bone, measured using conventional dual photon absorptiometry techniques, and insertion torque can predict part of the ultimate failure strength of interference screw fixation of quadrupled hamstring tendon grafts. The semitendinosus and gracilis tendons were harvested from 10 human cadaveric knees, mean age 66.5 years (range, 53 to 81). The bone tunnel was sized within 0.5 mm of the graft. The graft was fixed with a biodegradable screw (7 x 25 mm for the femur, and 9 x 25 mm for the tibia) directly against the tendon and at the joint surfaces. Tibial fixation and femoral fixation were tested to failure using a materials testing system. Bone mineral density was measured in the metaphyseal region of the tibia and femur. The results of multiple regression analyses showed that both insertion torque and bone mineral density were related to the maximum load the graft withstood. These two variables explained 77.1% of the maximum load observed. We concluded that bone mineral density measurements of the host bone site are an important determinant of postoperative graft strength and thus have an important, but previously unrecognized, clinical role in establishing individual postsurgery rehabilitation protocols. Insertion torque in this study was a useful predictor of graft fixation strength.

Aged↗
PubMedDate not supplied

Graft fixation in cruciate ligament reconstruction.

Cruciate ligament reconstruction has progressed dramatically in the last 20 years. Anatomic placement of ligament substitutes has fostered rehabilitation efforts that stress immediate and full range of motion, immediate weightbearing, neuromuscular strength and coordination, and early return to athletic competition (3 months). This has placed extreme importance on secure graft fixation at the time of ligament reconstruction. Current ligament substitutes require a bony or soft tissue component to be fixed within a bone tunnel or on the periosteum at a distance from the normal ligament attachment site. Fixation devices have progressed from metal to biodegradable and from far to near-normal native ligament attachment sites. Ideally, the biomechanical properties of the entire graft construct would approach those of the native ligament and facilitate biologic incorporation of the graft. Fixation should be done at the normal anatomic attachment site of the native ligament (aperture fixation) and, over time, allow the biologic return of the histologic transition zone from ligament to fibrocartilage, to calcified fibrocartilage, to bone. The purpose of this article is to review current fixation devices and techniques in cruciate ligament surgery.

Anterior Cruciate Ligament↗
PubMedDate not supplied

Effect of screw length on bioabsorbable interference screw fixation in a tibial bone tunnel.

Initial tibial fixation strength is the weak link after anterior cruciate ligament reconstruction with a quadrupled hamstring tendon graft fixed with bioabsorbable interference screws. The purpose of this study was to determine the biomechanical differences between 28-mm and tapered 35-mm interference screws for tibial fixation of a soft tissue graft in 16 young cadaveric tibias. Failure mode, displacement before failure, and ultimate failure load were tested with a testing machine aligned with the tibial tunnel to simulate a worst-case scenario. The mode of failure was graft slippage past the screw in all but one of the specimens. The mean maximum load at failure of the 28-mm screw was 594.9 +/- 141.0 N, with mean displacement at failure of 10.97 +/- 2.20 mm. The mean maximum load at failure of the 35-mm screw was 824.9 +/- 124.3 N, with a mean displacement to failure of 14.38 +/- 2.15 mm. The 38% difference in mean maximal load at failure was significant. Important variables in hamstring tendon graft fixation within a bone tunnel include bone mineral density, dilatation, gap size, screw placement, and screw width and length. Attention to these variables will help to provide secure graft fixation during biologic incorporation throughout the rehabilitation period.

Absorbable Implants↗
PubMedDate not supplied

Rupture of the pectoralis major muscle in a collegiate football player. Use of magnetic resonance imaging in early diagnosis.

We have reported an unusual case of pectoralis major muscle rupture and repair. There were three interesting aspects of this case. First, the injury occurred in a football player with an unusual mechanism of injury. Second, MRI using special techniques was valuable in confirming the diagnosis acutely and in planning treatment. Finally, we reported on the use of suture anchors to secure the avulsed tendon. We recommend the early use of MRI for diagnosis and in planning treatment of suspected pectoralis major muscle ruptures.

Adult↗
PubMedDate not supplied

Articular cartilage changes seen with magnetic resonance imaging-detected bone bruises associated with acute anterior cruciate ligament rupture.

Occult osteochondral lesions (bone bruises) have been documented on magnetic resonance images in more than 80% of patients sustaining acute anterior cruciate ligament ruptures. Despite the high prevalence of these lesions, little is known about the histologic changes in the adjacent articular cartilage. Ten patients with acute anterior cruciate ligament ruptures who had a preoperatively documented (by magnetic resonance imaging) geographic bone bruise at the sulcus terminalis on the lateral femoral condyle underwent a 3-mm diameter trephine biopsy of the articular cartilage and subchondral bone overlying the bone bruise at the time of anterior cruciate ligament reconstruction. Biopsy samples of the articular cartilage and subchondral bone were stained with hematoxylin and eosin and toluidine blue. All patients had significant arthroscopic and histologic articular cartilage irregularity in the area overlying the bone bruise. Arthroscopic findings of the articular cartilage included softening (dimpling), fissuring, or overt chondral fracture. Histologic examination revealed degeneration of the chondrocytes and loss of toluidine blue staining in the articular cartilage (loss of proteoglycan). There was necrosis of osteocytes in the subchondral bone, and empty lacuna were visible. This study defines the exact histologic changes of the articular cartilage overlying a geographic bone bruise secondary to an acute anterior cruciate ligament tear. Our findings suggest that a geographic bone bruise found on magnetic resonance imaging indicates substantial damage to normal articular cartilage homeostasis.

Adolescent↗
PubMedDate not supplied

Association of early bilateral middle ear effusion with language at age 5 years.

OBJECTIVE: This study tested the hypothesis that children with early persistent middle ear effusion (MEE) are at risk for later language deficit. METHOD: We recruited 698 newborns and monitored them for MEE every 2 to 4 weeks at home until age 3 years. Language skills were assessed on 294 subjects at age 5, while controlling for 8 demographic and environmental factors. Language outcomes at age 5 years were studied as a function of duration of bilateral MEE from birth to age 3 years. RESULTS: A significant relation was found between duration of bilateral MEE and speech sound sensitivity (Carrow Elicited Language Inventory) and articulation (Goldman-Fristoe Articulation). Children's ability to discriminate speech sounds in a quiet environment (Carrow Auditory Visual Abilities Test) was less affected by early prolonged MEE in homes that provided more cognitive stimulation. CONCLUSIONS: These exploratory results indicate that prolonged early MEE may predispose children to language deficits at age 5 years. The language deficits are of small magnitude and may or may not be clinically significant. Language stimulation at home may protect against some of the effects of prolonged MEE.

Acoustic Impedance Tests↗