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Biomedical subjects

R M Johnston

Publications and source records attributed to R M Johnston.

13 recordsLinked to original sources
PubMed1992

Constrained and flexible features of rhythmical hindlimb movements in chicks: kinematic profiles of walking, swimming and airstepping.

Although studies of walking have generated many of the principles for motor control, walking is but one of the many behaviors that an animal produces. This study investigates the relationships among the kinematic profiles of three behaviors in chicks: walking, swimming and airstepping. In addition to describing features of the hindlimb movements, such as retraction and protraction, we also examined the intra- and interjoint coordination patterns at the hip, knee and ankle. By using multiple levels of analysis, we identified some features that are common to all three behaviors, and therefore appear to be constrained, as well as some dissimilar or flexible features. Specifically, we show that resistance differentially affects the hip, knee and ankle joints. Our results also show that each joint plays a distinctive role in these behaviors. For example, we suggest that the hip stabilizes the hindlimb and regulates the rhythmicity of its movements. We also show that movement at the knee consistently precedes movement at the other joints in each behavior. Finally, differences in ankle movements are the key features that discriminate one behavior from another. Continuity among prenatal, perinatal and postnatal behaviors in chicks is discussed.

Animals↗
PubMed1987

Cardiac transplantation: first-year experience in a community hospital.

The issue of decentralizing heart transplant services, formerly restricted to a few large medical centers, is currently under review by federal and state governments. We present the results of the first year of cardiac transplantation at a 385-bed community hospital. Twelve patients were selected according to generally accepted criteria from a pool of 24 referrals, all from within 75 miles of our institution. All patients were in New York Heart Association Class IV preoperatively. The one-year survival rate was found to be 82%, which is equivalent to that reported by established centers. All surviving patients were fully rehabilitated. Rates of infection and rejection were lower than expected, and costs were about half the national average. This series, in all likelihood, tests the limits to which the decentralization of cardiac transplant services can be taken. We conclude that cardiac transplantation can be accomplished at a community hospital with results, even for the first patients undergoing transplantation, comparable to those obtained by established programs at major medical centers.

Adult↗
PubMed1983

Ununited fractures of the clavicle.

We reviewed the cases of thirty-three patients with non-union of a clavicular fracture. The patients who seemed to have a predilection to non-union were seven who had sustained a refracture and twenty-one who had had severe trauma. Eleven patients had an atrophic non-union, and these lesions were less symptomatic than the hypertrophic non-unions in the series. Only three of the eleven patients with an atrophic non-union had an operation, compared with sixteen of the twenty-two patients with a hypertrophic non-union. The results in the nineteen patients who underwent the various surgical procedures (twenty-five operations) showed that the most successful procedure was internal fixation and bone-grafting. Even though union was achieved in twelve patients who were surgically treated, mild to moderate symptoms persisted in some.

Adolescent↗
PubMed1980

Abdominal trauma associated with pelvic fracture.

Seventy consecutive surviving patients with pelvic fractures were reviewed to define those at high risk for intra-abdominal injury. Eleven (16%) had serious associated visceral injuries. Initial hypotension, Malgaigne and bilateral pubic rami fractures, and blood requirements exceeding 2,000 cc were suggestive of abdominal trauma. These high-risk patients should undergo peritoneal lavage as an integral part of their initial management. If the lavage is negative, continued hemorrhage should be evaluated with angiography and nonoperative means of vascular control attempted before resorting to laparotomy.

Abdominal Injuries↗
PubMedDate not supplied

Early prediction of avascular necrosis of the femoral head following femoral neck fractures.

The treatment of acute fracture of the femoral neck remains an unsolved problem. Fifty-three patients are presented using 99mTc phosphate scintigraphy with quantitative computer interpretation to predict the viability of the femoral head following acute fracture. The accuracy of prediction was 92.5%; the scans were incorrect in four patients. Armed with a safe, simple diagnostic procedure and a greater than 90% accurate prognosis, a rational program of treatment can be prescribed for the individual patient.

Adolescent↗