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Biomedical subjects

C Lindquist

Publications and source records attributed to C Lindquist.

At least 19 recordsLinked to original sources
PubMed2001

Extracellular amino acid levels measured with intracerebral microdialysis in the model of posttraumatic epilepsy induced by intracortical iron injection.

An iron induced model of posttraumatic chronic focal epilepsy in rats was studied with respect to extracellular amino acids, electrophysiology, and morphology, approx. 6 months after intracortical injection of ferrous chloride. Twenty-six of the twenty-eight (93%) rats developed spontaneous epileptiform EEG-activity and electrical cortical stimulation done in eight animals evoked seizure activity in five animals (62.5%). Epileptic brain tissue displayed significantly higher extracellular interictal levels of aspartate (ASP), compared to normal brain, measured with intracerebral microdialysis. The interictal levels of serine (SER) were significantly higher at the lesion side compared to the contralateral cortex in epileptic animals. Spontaneous elevations of ASP and glutamate (GLU) levels up to 8 times the basal level were found in 4/5 (80%). There was no consistent amino acid pattern following the electrically induced seizures, but in association with more intense seizure activity ASP and GLU were elevated. Histopathologically, the necrotic lesions in the cortex contained small vessels and iron pigment loaded astrocytes. Scattered eosinophilic neurons were found in the hippocampus, bilaterally in 37% of the animals. The results show that a focal epileptiform activity developed in a high percentage of animals that received an intracortical iron injection. The observed amino acid changes in epileptic animals may be involved in the development of seizures in this model of posttraumatic epilepsy.

Amino Acids↗
PubMed2001

Review of evaluation tools used to assess the impact of nutrition education on dietary intake and quality, weight management practices, and physical activity of low-income audiences.

Nutrition education programs and social marketing campaigns frequently focus on low-income audiences with the goal of improving dietary intake and quality, weight management practices, and physical activity. The impact of nutrition education can be assessed by measuring change in relation to any or all of these broad variables. Unfortunately, little information is available concerning the reliability, validity, and sensitivity to change of measures used to assess these constructs with low-income audiences of adults and adolescents. This article reviews the literature and discusses the types of available measures that have been used and evaluated for the above audiences. It describes specific measures used to assess total diet, consumption of food groups from the Food Guide Pyramid, and behaviors related to weight management and physical activity. Overall, this review suggests that there is a critical need for additional development and evaluation of dietary quality measurement tools for low-income and minority audiences.

Body Weight↗
PubMed2001

What is the optimal therapy of brain metastases?

The conclusions of a symposium held in London in October 1999 and devoted to the optimal management of brain metastatic disease were: 1. Prognostic factors are: size and number of metastases (and the presence of mass effect); the status of the systemic cancer outside the central nervous system; performance/neurological status; the age of the patient; and the type of cancer. 2. Surgical management of the single, superficially located brain metastasis with symptomatic mass effect is recommended in good performance status patients. Many would follow this routinely by whole brain radiotherapy. 3. Whole brain radiotherapy is often not followed by durable control of the disease and carries morbidity; better management plans are required. In poor prognosis patients the delivery of radiotherapy may not always be indicated. 4. The current literature demonstrates that stereotactic radiosurgery can enhance the likelihood of sterilizing individual brain metastases compared with whole brain radiotherapy alone. 5. The results of questionnaire showed that the histological diagnosis and latency to onset made little difference to the opinion of neuroscience clinicians, who generally favoured stereotactic radiation therapy over whole brain radiotherapy (with or without a conventionally delivered boost) for all patients with less than four metastases. The opinions of oncologists differed. For bronchial and breast cancer patients, whole brain radiotherapy, with or without a boost, was favoured by the majority, particularly in oat cell cancer. However, with a long latency to 'isolated' brain metastasis, oncologists favoured focal radiation therapy. There was a strong preference amongst oncology experts to reserve stereotactic radiation therapy for apparently isolated brain metastasis; this opinion applied to bronchus and breast cancer, and also to melanoma. 6. Whole brain radiotherapy followed by positron emission tomography scanning to determine what viable metastatic disease remained (and potentially treatable by stereotactic/focal technology) was favoured by most of delegates who answered this question.

Brain Neoplasms↗
PubMed2000

Influence of body composition on the accuracy of reported energy intake in children.

OBJECTIVE: Mis-reporting dietary intake is a substantial barrier to understanding the role of dietary behavior in disease. Work with adults indicates that heavier individuals under-report dietary intake and that under-reporting may be macronutrient-specific. Whether weight status and macronutrient intake influence the accuracy of dietary reports among children, however, is less clear. This research evaluated children's dietary reporting accuracy as a function of their relative weight, body composition, and macronutrient intake. RESEARCH METHODS AND PROCEDURES: Participants included 146 4- to 11-year-old children. Reported energy intake was determined by interviewing children in the presence of parents, using three multiple pass, 24-hour recalls. Children were classified as having had an under-reported, accurately reported, or over-reported dietary intake relative to total energy expenditure, as measured by doubly labeled water. Reporting accuracy was examined as a function of children's body weight, body composition (using dual energy x-ray absorptiometry), and macronutrient intake. RESULTS: Average reported intake was, on average, 14% greater than children's estimated expenditure (p < 0.01). Reporting accuracy varied as a function of children's relative weight and body composition; under-reporting tended to occur among heavier children, having the highest body fat content (p < 0.0001) and relative weight (p < 0.0001). DISCUSSION: These findings suggest that weight status influences the accuracy of dietary reports made by children and their parents. More research is needed to address possible psychological and social factors that introduce bias in reporting children's dietary data.

Absorptiometry, Photon↗
PubMed1999

Lack of infection in HIV-exposed individuals is associated with a strong CD8(+) cell noncytotoxic anti-HIV response.

Individuals repeatedly exposed to HIV, but who remain uninfected, form a population enriched for persons likely to have either natural or acquired resistance to the virus. We have studied four such exposed uninfected cohorts, representing 60 individuals, for evidence of protective immunity. This population included participants exposed to HIV through anal or vaginal receptive intercourse on multiple occasions over many years. We observed CD8(+)-cell noncytotoxic inhibition of HIV replication in acutely infected CD4(+) cells in the vast majority of individuals most recently exposed to the virus (within 1 year). The levels of this CD8(+)-cell response were sufficient to inhibit the in vitro infection of the exposed subjects' peripheral blood mononuclear cells. We found no evidence of a significant role for CCR5 Delta32 mutation in this population, nor did CD4(+) cell susceptibility to infection or HIV-specific cytotoxic T-lymphocytes correlate with resistance to infection in the individuals tested. Therefore, the observed strong noncytotoxic CD8(+)-cell anti-HIV responses may be an antiviral immune activity contributing to the apparent protection from infection in these exposed uninfected individuals.

Adult↗
PubMed1999

Lesion topography and outcome after thermocapsulotomy or gamma knife capsulotomy for obsessive-compulsive disorder: relevance of the right hemisphere.

OBJECTIVES: Obsessive-compulsive disorder is a common mental disorder, notorious for its chronicity and intractability. Stereotactic lesions within the anterior limb of the internal capsule have been shown to provide symptomatic relief in such refractory cases, but only few systematic evaluations have correlated anatomic lesion location with individual postoperative outcome. PATIENTS AND METHODS: Between 1976 and 1989, extremely disabled and otherwise intractable patients with a chronic deteriorating clinical course of obsessive-compulsive disorder underwent bilateral thermocapsulotomy (n = 22) or radiosurgical gamma knife capsulotomy (n = 13) at the Karolinska Hospital, Stockholm. Clinical morbidity was monitored prospectively pre- and postoperatively by using standardized psychiatric rating scales. In 29 patients (thermocapsulotomy, n = 19; gamma knife capsulotomy, n = 10), both psychiatric and magnetic resonance imaging follow-up data (median, 8.4 yr) were available. RESULTS: A right-sided anatomically defined lesion volume was identified in all successfully treated patients. This common topographic denominator was defined in the approximate middle of the anterior limb of the internal capsule on the plane parallel to the anterior commissure-posterior commissure line at the level of the foramen of Monro and 4 mm above on the plane defined by the internal cerebral vein. This region was unaffected in patients with poor outcomes. On the left side, no particular lesion topography was associated with clinical outcome. Topographic differences of lesion overlap between good and poor outcome groups were significant for the right side (Fisher's exact test, P < 0.005). CONCLUSION: The current anatomic long-term analysis after thermocapsulotomy or gamma knife capsulotomy for obsessive-compulsive disorder reveals common topographic features within the right-sided anterior limb of the internal capsule independent of treatment modality.

Adult↗
PubMed1999

Drinking patterns in the American Deep South.

OBJECTIVE: To determine whether the states of the Deep South are characterized by contradictory drinking norms: high abstinence paired with high consumption among drinkers. METHOD: Comparison of survey results of drinking patterns (N = 65,216) in four states of the Deep South (Alabama, Georgia, Louisiana and Mississippi) to those in leading states in the East (New York), Midwest (Illinois), Rocky Mountains (Colorado) and West (California) for the years 1990-93. Respondents were selected by random-digit dialing and interviewed by telephone as part of a larger study conducted by the Behavioral Risk Factor Surveillance System (BRFSS) of the Centers for Disease Control and Prevention (CDC). RESULTS: A higher proportion of persons drank alcohol in 1993 than in any of the previous 3 years. Persons with higher education, with higher income, of younger age, male, white and not living in the Deep South were more likely to drink. Among drinkers, the likelihood of episodic heavy drinking decreased with higher education, income and age. In addition, women, blacks and married respondents were less likely to report heavy drinking. Region of residence is not significantly associated with episodic heavy drinking. CONCLUSIONS: The Deep South has a significantly higher proportion of abstainers from alcohol use than other regions. Among drinkers, Southerners are not more likely to engage in occasions of heavy drinking. The results are discussed in relation to Southern culture and drinking norms.

Adolescent↗
PubMed1998

Gamma knife surgery for previously irradiated arteriovenous malformations.

OBJECTIVE: The goal was to report the treatment results after a second gamma knife treatment and to compare them with the results obtained after a first gamma knife treatment, as well as to investigate whether the models to predict the results after a first treatment are also applicable after gamma knife treatment of previously irradiated arteriovenous malformations. METHODS: The number of complications and the posttreatment hemorrhage rate were recorded for 112 patients in the study, and the number of obliterations was recorded for the 101 patients for whom conclusive angiograms were obtained. The results were compared with the expected results after a first gamma knife treatment. RESULTS: The observed number of obliterations was 62, which is not significantly different from the predicted number of 65. There were 14 observed and 5 predicted complications. When the risk from the preceding radiation treatment was added, the observed number of complications was similar to the predicted number. Six hemorrhages were observed after the second treatment. Of the 5 patients with unchanged arteriovenous malformation size after both the first and second treatments, 2 experienced hemorrhages after the second treatment, compared with none among the 81 patients for whom the malformation was obliterated or significantly decreased in size after the second treatment. CONCLUSIONS: The obliteration rate after gamma knife surgery for previously irradiated arteriovenous malformations is similar to that after primary gamma knife treatment. The complication rate increases with the amount of radiation previously given. The incidence of posttreatment hemorrhages is lower in the latency period if the malformation is affected by the radiation.

Adolescent↗
PubMed1998

Radiosurgery for cavernous malformations.

OBJECT: The authors examined 22 patients with cavernous malformations (CMs) who had undergone gamma knife radiosurgery (GKRS) to assess the value of this procedure in treating these lesions. METHODS: At the Karolinska Hospital, GKRS was used to treat 23 patients with CMs during the period of 1985 through 1996. One of the patients was lost to follow up and the treatment results of the 22 remaining patients were analyzed. In the first half of the series, the CMs were treated with high doses of radiation (> 15-Gy dose to the periphery); in the second half of the series, lower doses were used. Nine of the 22 patients suffered a post-GKRS hemorrhage and six developed a radiation-induced complication (two of these patients experienced both). Some time after GKRS was performed, surgical removal of the CM had to be undertaken in four patients because of hemorrhage and in two patients because of radiation-induced complications. Four of the nine patients who experienced no post-GKRS hemorrhage or radiation-induced complication were treated before 1990; recent magnetic resonance imaging revealed a decrease in the size of the CM in three of these individuals and no size change in the other. The annual post-GKRS hemorrhage rate was 8% in this group. There was a trend in the hemorrhage rate to decrease 4 years postsurgery. There was also a trend for higher radiation doses administered to the periphery of the lesion to result in a lower risk of posttreatment hemorrhage. However, it could not be concluded whether GKRS affects the natural course of a CM. The incidence of radiation-induced complications was approximately seven times higher than that expected if the same number of patients had been treated by GKRS with the same radiation dose distributions for arteriovenous malformations instead of CMs. CONCLUSIONS: The high incidence of radiation-induced complications does not seem to justify the limited protection the treatment may afford in only exceptional cases. A prospective randomized study is needed before the role of radiosurgery in the management of these lesions can be defined. Until such a study has proved differently, a caveat must be raised for the treatment of CM with GKRS.

Cavernous Sinus↗
PubMed1997

In vivo forces during remodeling of a two-segment anterior cruciate ligament graft in a goat model.

An existing goat model was used to measure in vivo graft forces during walking, to determine if the forces set at surgery change over time under the same external load and if the forces in the graft during in vivo function can be dictated by the forces set at surgery. The anterior cruciate ligament was reconstructed in 12 goats with use of a composite graft consisting of a bone-patellar tendon-bone autograft and a synthetic augmentation segment. The forces in the graft segments were established intraoperatively by a force-setting technique. In five animals, the tendon segment was set to carry 90% of the total graft force, and in the seven other animals, the augmentation segment was set to carry 90% of the total force. The total graft force was the same in all animals. Graft forces due to anterior tibial loads of 67 N were measured before and after fixation and 6 weeks after surgery with the use of buckle transducers mounted extra-articularly over the anterior tibia. They were also measured during straight, level walking at 6 weeks. The forces changed significantly from just after surgery to 6 weeks later, such that the initially set load-sharing was eliminated by 6 weeks. At 6 weeks, a relatively smooth gait had been achieved, and the maximum total graft force in each animal during walking averaged 35 N and was of similar magnitude to forces generated by the anterior tibial loads of 67 N with the animal anesthetized. After fixation, forces in the tendon graft segments were significantly different between the group with high set forces and that with low set forces. At 6 weeks, when functional joint loads were approaching normal levels, the graft segment forces for the two groups were not significantly different. Load-sharing between tendon and augmentation segment and load in the tendon segment at 6 weeks could not be dictated at surgery.

Animals↗
PubMed1997

Obsessive compulsive disorder and the right hemisphere: topographic analysis of lesions after anterior capsulotomy performed with thermocoagulation.

Considerable but uncontrolled evidence suggests that stereotactic capsulotomy by means of thermolesions may provide symptomatic relief for patients with otherwise therapy refractory "malignant" obsessive compulsive disorder (OCD). Unlike in other functional stereotactic interventions, target localization for capsulotomy is based upon anatomical definition only. Few systematic attempts have been made to correlate the site and size of the capsular lesions with postoperative clinical outcome. Between 1976 and 1989 bilateral thermo-capsulotomy (TC) was performed in 22 OCD patients. In 19 patients complete quantitative pre- and postoperative psychiatric rating of OCD symptoms and long-term postoperative MRI studies were available. Cohorts of patients fulfilling criteria for good or poor outcome were contrasted, cases with intermediate treatment effect being excluded. Median postoperative MRI follow-up was 8.4 years (2.4-20.3 y). 9/19 patients fulfilled criteria for good postoperative outcome. In these patients all lesion sites overlapped covering a small area within the right anterior limb of the internal capsule. Lesions within the group of patients with poor outcome (n = 5) were located elsewhere, mostly further anterior in the internal capsule. Differences of lesion overlap between the two outcome groups were significant for the right side (Fisher's Exact Test: p < 0.005). Common topographic features of lesion sites within the right internal capsule were identified in OCD patients responding favourably to capsulotomy.

Adult↗
PubMed1997

Annual risk for the first hemorrhage from untreated cerebral arteriovenous malformations.

To estimate the annual risk for the first hemorrhage, survival and life table statistics were used to analyze data from 2262 patients with cerebral arteriovenous malformations (AVM). We found that the risk for hemorrhage increases with increasing age. A validity test revealed, however, that life table statistics used on the total patient material underestimated the annual risk for hemorrhage, especially for patients 20-50 years of age. A method based on the fact that the distribution of the time at risk until the initial hemorrhage (= age at first rupture) reflects the risk for hemorrhage in untreated AVM was therefore also employed. The analysis yielded three conclusions: 1) the annual risk of hemorrhage increases with age; 2) small AVM are less prone to rupture; and 3) the risk of hemorrhage is higher in women during their fertile years as compared to males in the same age group. The risk related to age, AVM size and location assessed by survival statistics in the subgroup of patients with a known date for the initial hemorrhage gave similar results.

Adolescent↗
PubMed1997

Prediction of obliteration after gamma knife surgery for cerebral arteriovenous malformations.

OBJECTIVE: To define the factors of importance for the obliteration of cerebral arteriovenous malformations (AVMs), thus making a prediction of the probability for obliteration possible. METHODS: In 945 AVMs of a series of 1319 patients treated with the gamma knife during 1970 to 1990, the relationship between patient, AVMs, and treatment parameters on the one hand and the obliteration of the nidus on the other was analyzed. RESULTS: The obliteration rate increased both with increased minimum (lowest periphery) and average dose and decreased with increased AVM volume. The minimum dose to the AVMs was the decisive dose factor for the treatment result. The higher the minimum dose, the higher the chance for total obliteration. The curve illustrating this relation increased logarithmically to a value of 87%. A higher average dose shortened the latency to AVM obliteration. For the obliterated cases, the larger the malformation, the lower the minimum dose used. This prompted us to relate the obliteration rate to the product minimum dose (AVM volume)1/3 (K index). The obliteration rate increased linearly with the K index up to a value of approximately 27, and for higher K values, the obliteration rate had a constant value of approximately 80%. For the group of 273 cases treated with a minimum dose of at least 25 Gy, the obliteration rate at the study end point (defined as 2-yr latency) was 80% (95% confidence interval = 75-85%). If obliterations that occurred beyond the end point are included, the obliteration rate increased to 85% (81-89%). CONCLUSION: The probability of obliteration of AVMs after gamma knife surgery is related both to the lowest dose to the AVMs and the AVM volume, and it can be predicted using the K index.

Adolescent↗
PubMed1997

Radiosurgical lesions in the normal human brain 17 years after gamma knife capsulotomy.

OBJECTIVE: To our knowledge, this is the first long-term follow-up study of high-dose single-session irradiation to the human brain and provides new data concerning late tissue reactions after irradiation to small target volumes. The long-term lesional brain changes in 14 patients subjected to bilateral gamma knife capsulotomy for otherwise intractable anxiety disorders were retrospectively analyzed by magnetic resonance imaging. METHODS: The prototype gamma unit was used for the radiosurgical procedure, and the collimators provided rectangular cross-sectional fields with an anteroposterior diameter of 3 mm and a transverse diameter of 5 or 11 mm. Maximum target doses were 120 to 180 Gy. Magnetic resonance imaging was performed 15 to 18 years (mean, 17 yr) after treatment, and dose-volume histograms were calculated for the dose distributions. RESULTS: One patient had been irradiated twice on one side. In all but one of the remaining 27 targets, lesions with a volume of less than 100 mm3 were revealed by magnetic resonance imaging. The volumes of the lesions were confined within the volume corresponding to a minimum dose of approximately 110 Gy, with one exception. In one of three targets receiving a maximum dose of 120 Gy, no lesion was detected. There were no late radiation effects such as cyst formations, telangiectasias, hemorrhagic infarctions, or neoplasms. CONCLUSION: This investigation indicates that a minimum dose of 110 Gy, with the currently used 4-mm collimator, to the edge of the target volume is required to create a lesion. The results prove that gamma knife surgery can be used in functional neurosurgery for producing small permanent lesions in the normal human brain.

Adult↗
PubMed1997

Mechanics of the anterior drawer and talar tilt tests. A cadaveric study of lateral ligament injuries of the ankle.

We analyzed the changes in lateral ligament forces during anterior drawer and talar tilt testing and examined ankle joint motion during testing, following an isolated lesion of the anterior talofibular ligament (ATFL) or a combined lesion of the ATFL and calcaneofibular ligament (CFL). 8 cadaver specimens were held in a specially designed testing apparatus in which the ankle position (dorsiflexion-plantarflexion and supination-pronation) could be varied in a controlled manner. Ligament forces were measured with buckle transducers, and joint motion was measured with an instrumented spatial linkage. An anterior drawer test was performed using an 80 N anterior translating force, and a talar tilt test was performed using a 5.7 Nm supination torque with intact ligaments, after sectioning of the ATFL, and again after sectioning of the CFL. The tests were repeated at 10 degrees dorsiflexion, neutral, and 10 degrees and 20 degrees plantarflexion. In the intact ankle, the largest increases in ATFL force were observed during testing in plantarflexion, whereas the largest increases in CFL force were observed in dorsiflexion. Isolated ATFL injury caused only small laxity changes, but a pronounced increase in laxity was observed after a combined CFL and ATFL injury.

Adult↗
PubMed1997

Third ventricle colloid cysts: a consecutive 12-year series.

A continuous follow-up review of colloid cysts including aspects of natural history and evaluation of treatment options is necessary to optimize individual treatment. Thirty-seven consecutive patients with colloid cyst of the third ventricle seen at Karolinska Hospital between 1984 and 1995 were reviewed. Five patients were admitted in a comatose state, and two died despite emergency ventriculostomy. Three had recurrent cysts following previous aspiration procedure. During the study period, patients underwent a total of 10 ventriculostomies, 10 aspirations, 26 microsurgical operations, and two shunt operations. Twenty-four of 26 microsurgical operations were transcallosal and two were transcortical. Twenty-four operations (22 transcallosal and two transfrontal approaches) without permanent morbidity were performed by four surgeons. Transient memory deficit from forniceal traction was noted in 26%. The remaining two transcallosal operations, which led to permanent morbidity or mortality, were performed by two different surgeons. Aspiration of cysts performed by four different surgeons carried a 40% risk of transient memory deficit (10% permanent) and an 80% recurrence rate. One patient was found to be cured on radiological studies obtained at the 5-year follow-up review. Seven cysts were followed by means of radiological studies with no treatment for 6 to 37 months. Five of these cysts grew, indicating that younger patients with colloid cysts will probably need surgical treatment. The main causes of unfavorable results were: 1) failure to investigate symptoms that proved fatal; 2) subtotal resection; and 3) surgical complications. Transcallosal microsurgery produced excellent results when performed by experienced surgeons. A colloid cyst of the foramen of Monro is a disease that should be detected before permanent neurological damage has occurred. Permanent morbidity or mortality should not be accepted in modern series of third ventricle colloid cysts.

Adolescent↗