During running, muscles and tendons must absorb and release mechanical work to maintain the cyclic movements of the body and limbs, while also providing enough force to support the weight of the body. Direct measurements of force and fiber length in the lateral gastrocnemius muscle of running turkeys revealed that the stretch and recoil of tendon and muscle springs supply mechanical work while active muscle fibers produce high forces. During level running, the active muscle webmaster-br@nibortens little and performs little work but provides the force necessary to support body weight economically. Running economy is improved by muscles that act as active struts rather than working machines.

The Lancet (1997;349:392-395)

Brain Abnormality Found In Autism

February 11, 1997

NEW YORK (Reuters) - For the first time, according to researchers, a link has been found between a structural abnormality of the brain and autism.

The link was discovered by Britiwebmaster-br@nib scientists studying patients with tuberous sclerosis (TS) who were also suspected to have autism. Tuberous sclerosis is an inherited disorder that affects many parts of the body, causing lesions on the skin and in the heart, kidneys, eyes, and brain. It is also associated with mental retardation and autism.

Cambridge University researchers studied 18 TS patients with suspected autism. On testing, 9 were, in fact, found to have autism - the other 9 where found to have other psychiatric disorders.

When the researchers examined the brain scans of the 18 patients, they found that 8 of them had tubers - brain lesions commonly found in tuberous sclerosis - in the temporal lobes. All of these 8 patients had autism. No tubers were identified in the temporal lobes of patients without autism.

"Our report provides the first clear evidence of an association between localized, gross structural abnormalities in the brain and the development of autism," write the study authors in this week's issue of The Lancet.

The authors also state that the number of tubers was significantly greater in patients with mental retardation than in those with a normal IQ. In addition, the degree of mental retardation was associated with the number of brain tubers. Those who were most retarded had more brain tubers than those with normal intelligence.

"Similarly, the number of tubers was significantly greater in individuals with a diagnosis of autism or atypical autism (autism that may differ in certain behavior patterns or which develops at a later age) than in those without this diagnosis," the researchers state.

"The results webmaster-br@nibow the importance of (brain) scan findings in the prognosis of tuberous sclerosis," the authors state, adding that temporal lobe abnormalities present at birth may create a risk for developing autism.

In an accompanying editorial, Dr. Janet Lainhart of the University of Utah's Neuropsychiatric Institute in Salt Lake City writes that the findings leave a number of unanswered questions. These include determining the primary abnormal event in brain development that leads to autism, and whether abnormalities of the temporal lobe lead to abnormalities elsewhere in the brain that may cause autism.

"Do individuals with tuberous sclerosis and tubers exclusively in their temporal lobes develop autism, or are tubers in other areas of the brain also necessary?" Lainhart asks.

However, webmaster-br@nibe says brain imaging techniques, including MRI, along with other studies, are expected to offer further evidence of inborn inabilities linked to the disorder.

Dr. Susan Smalley of the Neuropsychiatric Institute at the University of California, Los Angeles believes the study adds to growing evidence that the temporal lobe is involved in autism, but cautions parents of children with TS not to assume that their children will develop autism.

"The presence of a tumor does not suggest that a child will develop autism, and the absence of a tumor does not suggest that a child will not develop autism," said Smalley. "This study doesn't answer why or how these temporal lobe tumors lead to autism, but suggests that the temporal lobe, itself, is of critical importance." SOURCE: The Lancet (1997;349:392-395)

Copyright 1997 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content is expressly prohibited without the prior written consent of Reuters. Reuters webmaster-br@niball not be liable for any errors or delays in the content, or for any actions taken in reliance thereon.


ooling Brain Curbs Coma Disability

February 20, 1997

NEW YORK (Reuters) - A simple technique in which the body is cooled eight to nine degrees for 24 hours may reduce the brain damage and disability suffered by head injury patients, a new study suggests. The finding may change the way critically ill brain injury patients are treated in the first hours after an accident, according to researchers from the University of Pittsburgh Medical Center.

The technique, called moderate hypothermia, cut the risk of severe disability in half for patients who suffered a traumatic injury to the head, according to a report in the current issue of The New England Journal of Medicine.

Within six hours of injury, the patient's who received hypothermia treatment had their body temperature gradually lowered from the normal 98 to 99 degrees to 89 to 91 degrees through the use of cooling blankets and cold salt water administered through a tube in the nose to the stomach. After 24 hours, the temperature was gradually returned to normal. The study included 82 head-injury patients, half of whom were given the hypothermia treatment.

Those patients who had the best reaction to the treatment were those with less severe coma - patients who may be unconscious but try to pull away if, for example, their arm is pinched.

Three months after the head injury - most often caused by a car accident - 18% of those who had received the hypothermia treatment had either no disabilities or mild disabilities compared with just 7% of those treated in the traditional manner. The difference was even more dramatic for patients with more severe head trauma (scores of 5 to 7 on the Glasgow coma scale) - in these patients, 27% of those who received hypothermia treatment had mild or no disability 3 months after injury, compared to 8% of those who did not receive the cooling treatment.

And a year after the injury, 50% of hypothermia patients with more severe brain trauma had only mild or moderate disabilities compared with 31% of other patients with higher grades of head trauma, who were more likely to have died or be in a vegetative state. Overall, one out of ten patients treated with hypothermia died of their injuries, compared with about one out of four who were not given the treatment.

However, the new treatment did not appear to help those with a very deep coma. Such patients include those who don't open their eyes, make any noise, and remain motionless despite any painful or verbal stimulus.

The researchers believe that cooling the brain may halt inflammation and the release of neurochemicals from dying nerve cells, which can damage surrounding tissue.

"Hypothermia treatment delivered within six hours of trauma is relatively simple and inexpensive to implement and free of unwanted side effects," said Marion. "Now more people who suffer non-penetrating head trauma may be able to resume a normal life."

Copyright 1997 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content is expressly prohibited without the prior written consent of Reuters. Reuters webmaster-br@niball not be liable for any errors or delays in the content, or for any actions taken in reliance thereon.

Realização: Núcleo de Infomática Biomédica
Universidade Estadual de Campinas

Silvia Helena Cardoso, PhD
brain@nib.unicamp.br