B-63 Subacute Cognitive Sequelae of Mild Traumatic Brain Injury on the Cambridge Neuropsychological Test Automated Battery (CANTAB) and Traditional Neuropsychological Tests

Objective

This study examined cognitive functioning at approximately two weeks following mild traumatic brain injury (MTBI) and explored whether tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) revealed greater differences between patients with MTBI and controls than traditional neuropsychological tests.

Method

Patients with MTBIs (n = 177) according to the World Health Organization criteria, trauma controls with orthopedic injuries (n = 79), and community controls (n = 81) were assessed with 18 neuropsychological tests an average of 17 days post injury (SD = 3 days). The tests consisted of both traditional, well-established, paper and pencil tests (9 tests, 11 outcome measures) and tests from the CANTAB battery (9 tests, 14 outcome measures).

Results

Of the 25 outcome measures, the groups only differed significantly on the Coding subtest from the WAIS-IV battery (uncorrected Kruskal-Wallis test: p = 0.025), with lower performance in the MTBI group compared to the community control group (Cliff’s delta = -0.20). Effect sizes of the differences between patients with MTBI and community controls ranged from -0.16 to 0.01 on the CANTAB tests and -0.20 to 0.00 on the traditional tests. Effect sizes of the differences between patients with MTBI and trauma controls ranged from -0.13 to 0.06 on the CANTAB tests and -0.15 to 0.02 on the traditional tests.

Conclusions

Patients with MTBI did not have significantly lower cognitive test performance than trauma controls or community controls on a large number of tests two weeks after injury. Further, differences between patients with MTBI and controls were similar for the CANTAB battery and traditional tests.

Impact of incident myocardial infarction on the risk of venous thromboembolism: the Tromsø Study

Essentials Registry-based studies indicate a link between arterial- and venous thromboembolism (VTE). We studied this association in a cohort with confounder information and validated outcomes. Myocardial infarction (MI) was associated with a 4.8-fold increased short-term risk of VTE. MI was associated with a transient increased risk of VTE, and pulmonary embolism in particular.

SUMMARY

Background Recent studies have demonstrated an association between venous thromboembolism (VTE) and arterial thrombotic diseases. Objectives To study the association between incident myocardial infarction (MI) and VTE in a prospective population-based cohort. Methods Study participants (n = 29 506) were recruited from three surveys of the Tromsø Study (conducted in 1994-1995, 2001-2002, and 2007-2008) and followed up to 2010. All incident MI and VTE events during follow-up were recorded. Cox regression models with age as the time scale and MI as a time-dependent variable were used to calculate hazard ratios (HRs) of VTE adjusted for sex, body mass index, blood pressure, diabetes mellitus, HDL cholesterol, smoking, physical activity, and education level. Results During a median follow-up of 15.7 years, 1853 participants experienced an MI and 699 experienced a VTE. MI was associated with a 51% increased risk of VTE (HR 1.51; 95% confidence interval [CI] 1.08-2.10) and a 72% increased risk of pulmonary embolism (PE) (HR 1.72; 95% CI 1.07-2.75), but not significantly associated with the risk of deep vein thrombosis (DVT) (HR 1.36; 95% CI 0.86-2.15). The highest risk estimates for PE were observed during the first 6 months after the MI (HR 8.49; 95% CI 4.00-18.77). MI explained 6.2% of the PEs in the population (population attributable risk) and 78.5% of the PE risk in MI patients (attributable risk). Conclusions Our findings indicate that MI is associated with a transient increased VTE risk, independently of traditional atherosclerotic risk factors. The risk estimates were particularly high for PE.

White matter microstructure in chronic moderate-to-severe traumatic brain injury: Impact of acute-phase injury-related variables and associations with outcome measures

This study examines how injury mechanisms and early neuroimaging and clinical measures impact white matter (WM) fractional anisotropy (FA), mean diffusivity (MD), and tract volumes in the chronic phase of traumatic brain injury (TBI) and how WM integrity in the chronic phase is associated with different outcome measures obtained at the same time. Diffusion tensor imaging (DTI) at 3 T was acquired more than 1 year after TBI in 49 moderate-to-severe-TBI survivors and 50 matched controls. DTI data were analyzed with tract-based spatial statistics and automated tractography. Moderate-to-severe TBI led to widespread FA decreases, MD increases, and tract volume reductions. In severe TBI and in acceleration/deceleration injuries, a specific FA loss was detected. A particular loss of FA was also present in the thalamus and the brainstem in all grades of diffuse axonal injury. Acute-phase Glasgow Coma Scale scores, number of microhemorrhages on T2*, lesion volume on fluid-attenuated inversion recovery, and duration of posttraumatic amnesia were associated with more widespread FA loss and MD increases in chronic TBI. Episodes of cerebral perfusion pressure <70 mmHg were specifically associated with reduced MD. Neither episodes of intracranial pressure >20 mmHg nor acute-phase Rotterdam CT scores were associated with WM changes. Glasgow Outcome Scale Extended scores and performance-based cognitive control functioning were associated with FA and MD changes, but self-reported cognitive control functioning was not. In conclusion, FA loss specifically reflects the primary injury severity and mechanism, whereas FA and MD changes are associated with objective measures of general and cognitive control functioning.

Stereoselective synthesis of protectin D1: a potent anti-inflammatory and proresolving lipid mediator

A convergent stereoselective synthesis of the potent anti-inflammatory, proresolving and neuroprotective lipid mediator protectin D1 (2) has been achieved in 15% yield over eight steps. The key features were a stereocontrolled Evans-aldol reaction with Nagao's chiral auxiliary and a highly selective Lindlar reduction of internal alkyne 23, allowing the sensitive conjugated E,E,Z-triene to be introduced late in the preparation of 2. The UV and LC/MS-MS data of synthetic protectin D1 (2) matched those obtained from endogenously produced material.

Risk factors for aneurysmal subarachnoid hemorrhage - BMI and serum lipids: 11-year follow-up of the HUNT and the Tromsø Study in Norway

OBJECTIVES

Life-style factors have been associated with the risk for aneurysmal subarachnoid hemorrhage (aSAH), but it is not clear whether body mass index (BMI) and serum lipids are associated with risk. We prospectively assessed these associations in two large population studies.

METHODS

A total of 65,526 participants in the Nord-Trøndelag Health Study (1995-1997) and 26,882 participants in the Tromsø Study (1994-1995) were included. Studies included measurements of body weight and height, serum lipids, and self-administered questionnaires. Participants who experienced aSAH were identified, and hazard ratios (HRs) were estimated using Cox regression analysis.

RESULTS

During 11 years of follow-up, aSAH was diagnosed in 122 participants. Overweight (BMI 25-29.9) was negatively associated with the risk of aSAH (HR 0.7, 95% CI 0.4-1.0). There was no over all association of total serum cholesterol, HDL cholesterol, or triglycerides with the risk of aSAH, but in participants younger than 50 years, HDL cholesterol was inversely associated with the risk (HR per standard deviation increase 0.6, 95% CI 0.4-0.9).

CONCLUSIONS

Overweight may be associated with reduced risk of aSAH, but there was no over all association of total serum cholesterol, HDL cholesterol, or triglycerides with the risk of aSAH in this prospective study.

Incidence and mortality of aneurysmal subarachnoid hemorrhage in two Norwegian cohorts, 1984-2007

OBJECTIVE

The incidence of aneurysmal subarachnoid hemorrhage (aSAH) ranges from 4 to 10 per 100,000 person-years in most countries, and 30-day case fatality is high. The aim of this study was to estimate the incidence and case fatality of aSAH and to assess preictal predictors of survival in 2 large Norwegian population-based cohort studies.

METHODS

A total of 94,976 adults (≥20 years) in the Nord-Trøndelag Health Study and 31,753 participants (aged ≥20 years) in the Tromsø Study were included. During follow-up, aSAHs were identified, incidence rates were estimated, and predictors of survival were assessed using Cox and Poisson regression analysis.

RESULTS

A total of 214 patients with aSAH were identified during 2,077,927 person-years of follow-up from 1984 to 2007. The incidence rate was 10.3 per 100,000 person-years: 13.3 for women and 7.1 for men. The incidence increased by 2% (95% confidence interval [CI] 0-4) per 5-year time period. Case fatality at 3, 7, and 30 days was 20%, 24%, and 36%. Thirty-day case fatality remained stable during follow-up (odds ratio 1.01, 95% CI 0.97-1.06 per year). Never smokers had poorer survival after aSAH than current and former smokers combined (hazard ratio 1.6, 95% CI 0.9-2.9).

CONCLUSIONS

The slight increase in incidence of aSAH over time may be explained by differences in diagnostic procedures. Case fatality remained stable during 23 years of follow-up.

Serum osteoprotegerin is a predictor for incident cardiovascular disease and mortality in a general population: the Tromsø Study

BACKGROUND

Osteoprotegerin (OPG) concentration in serum is associated with the presence and severity of atherosclerosis.

OBJECTIVE

To investigate the association between serum osteoprotegerin and the risk of a future myocardial infarction, ischemic stroke and mortality in a general population.

PATIENTS/METHODS

OPG was measured in serum collected from 6265 subjects recruited from a general population without a prior myocardial infarction and ischemic stroke (the Tromsø Study). Incident myocardial infarction, ischemic stroke and mortality were registered during follow-up. Cox regression models were used to estimate crude and adjusted hazard ratios and 95% confidence intervals (HR; 95% CI).

RESULTS

There were 575 myocardial infarctions, 284 ischemic strokes and 824 deaths (146 deaths as a result of ischemic heart disease, 78 deaths because of stroke and 600 deaths due to other causes) in the cohort during a median of 10.6 years of follow-up. Serum OPG (per SD [1.13 ng mL(-1)] increase in OPG) was associated with an increased risk of a myocardial infarction (1.20; 1.11-1.31), ischemic stroke (1.32; 1.18-1.47), total mortality (1.34; 1.26-1.42), death because of ischemic heart disease, (1.35; 1.18-1.54), stroke (1.44; 1.19-1.75) and non-vascular causes (1.31; 1.22-1.41) after adjustment for age, gender, current smoking, systolic blood pressure, body mass index, high density lipoprotein cholesterol, total cholesterol, creatinine, high sensitivity C-reactive protein (CRP) and diabetes mellitus or HbA1c > 6.1%. No association was detected between OPG and incident hemorrhagic stroke (1.02; 0.73-1.43).

CONCLUSIONS

Serum OPG was associated with future risk of myocardial infarction, ischemic stroke, total mortality, mortality of ischemic heart disease, stroke and of non-vascular causes independent of traditional cardiovascular risk factors.

Relation between serum osteoprotegerin and carotid intima media thickness in a general population - the Tromsø Study

BACKGROUND

 Previous studies have reported conflicting results on the relation between serum osteoprotegerin (OPG) concentration and carotid intima media thickness (CIMT).

PATIENTS/METHODS

 The present study was conducted to investigate the relations between OPG, risk factors for cardiovascular diseases (CVD) and carotid intima media thickness (CIMT) in a large cross-sectional study including 6516 subjects aged 25-85years who participated in a population-based health survey.

RESULTS

 CIMT increased significantly across tertiles of OPG after adjustment for traditional cardiovascular risk factors such as age, gender, smoking, total cholesterol, high-density lipoprotein (HDL) cholesterol, C-reactive protein (CRP), body mass index (BMI), systolic blood pressure, CVD and diabetes mellitus (P<0.0001). There was a significant interaction between age and OPG (P=0.026). The risk of being in the uppermost quartile of CIMT was reduced (OR 0.52, 95% CI 0.30-0.88) with each standard deviation (SD) higher level of OPG in subjects <45years (n=444), whereas subjects ≥55years of age (n=4884) had an increased risk of being in the uppermost quartile of CIMT (OR 1.19, 95% CI 1.10-1.29) after adjustment for traditional CVD risk factors.

CONCLUSIONS

Age has a differential impact on the association between OPG and CIMT in a general population. The present findings may suggest that increased serum OPG does not promote early atherosclerosis in younger subjects.

Overall survival, prognostic factors, and repeated surgery in a consecutive series of 516 patients with glioblastoma multiforme

OBJECTIVES

To study overall survival (OS), prognostic factors, and repeated surgery in glioblastoma multiforme (GBM).

MATERIAL AND METHODS

Retrospective study of 516 consecutive adult patients who underwent primary surgery for a GBM in year 2003-2008.

RESULTS

Median age at primary surgery was 63.7 years (range 18.0-88.0). Median OS was 9.9 months. Age > 60 years, poor preoperative ECOG score, bilateral tumor, biopsy rather than resection, and no temozolomide chemoradiotherapy were negative risk factors. Repeat surgery was performed in 65 patients (13%). Median time between first and second surgery was 7 months. Indications for second surgery were increasing neurological deficits (35.4%), raised ICP (33.8%), asymptomatic but reoperated because of tumor progression verified on MRI (20.0%), and epileptic seizures (11%). Patients who underwent repeated surgery had longer OS; 18.4 months vs 8.6 months (P < 0.001).

CONCLUSIONS

OS for adult GBM patients was 9.9 months. Negative prognostic factors were increasing age, poor neurological function, bilateral tumor involvement, biopsy instead of resection, and RT alone compared to temozolomide chemoradiotherapy. Our rate of repeated surgery for GBM was 13% and the main indications for second surgery were raised ICP and increasing neurological deficits. In a carefully selected group of patients, repeat surgery significantly prolongs OS.

Bone loss in relation to serum levels of osteoprotegerin and nuclear factor-kappaB ligand: the Tromsø Study

SUMMARY

In this longitudinal study of 4,137 persons, bone mineral density was negatively associated with osteoprotegerin at baseline in both genders. In postmenopausal women not using hormone replacement therapy (HRT), bone-loss increased with increasing osteoprotegerin levels, whereas no relationship was found in men, premenopausal women, or postmenopausal women taking HRT.

INTRODUCTION

In a population-based study of 2,003 men and 2,134 women, the relationship between the osteoprotegerin (OPG)/factor-kappaB ligand (RANKL) system and bone mineral density (BMD) and changes in BMD was examined.

METHODS

Baseline measurements included height, weight, BMD of the forearm, OPG, RANKL, vitamin D, and serum parathyroid hormone (PTH) and information about lifestyle, prevalent diseases, and use of medication. BMD was remeasured at follow-up 6 years later.

RESULTS

BMD was negatively associated with OPG at baseline in both men and women (p trend over OPG levels = 0.01 and 0.007, respectively, after adjustments for age, and other confounders). In postmenopausal women not on hormone replacement therapy, bone loss increased with increasing OPG (p = 0.005), whereas no relationship was found in men, premenopausal women, or postmenopausal women on HRT (p >or= 0.28). BMD at baseline and BMD changes were not related to RANKL levels in any of the groups (p >or= 0.14).

CONCLUSIONS

In postmenopausal women not using HRT, bone loss associated positively with OPG. The results indicate that in women deficient in sex steroids, the OPG/RANKL system may play an important counter regulatory role in order to avoid bone loss and maintain BMD. In men and women replete in sex steroids, the OPG/RANKL system was not associated with BMD.

Serum osteoprotegerin, sRANKL and carotid plaque formation and growth in a general population--the Tromsø study

SUMMARY BACKGROUND

Intervention studies in animal models suggest that osteoprotegerin (OPG) functions as an inhibitor or marker of atherosclerosis, whereas one prospective epidemiological study in humans indicated that OPG was an independent risk factor for progression of atherosclerosis.

OBJECTIVE

To study the association between serum levels of OPG, soluble RANK ligand (sRANKL) and carotid artery plaque formation and plaque growth.

PATIENTS/METHODS

The prevalence of carotid plaque and plaque area were assessed by ultrasonographic imaging at baseline and after 7 years follow-up in 2191 men and 2329 women who participated in a population-based study.

RESULTS

OPG was significantly associated with atherosclerotic plaque burden and cardiovascular risk factors such as age, body mass index, blood pressure, total cholesterol, HDL cholesterol, HbA1c and fibrinogen at baseline, but not with sRANKL. In subjects without plaque at baseline, OPG predicted plaque formation in crude analysis in both women and men, but not after adjustment for age and other atherosclerotic risk factors. OPG predicted plaque growth in women (+1.8 mm(2), 0.6-3.0) (mean, 95% CI) per 1 SD increase in OPG (P = 0.003), whereas no associations were demonstrated in men (0.1 mm(2) (-1.3-1.4), P = 0.93). Soluble RANKL did not predict plaque formation or plaque growth.

CONCLUSIONS

OPG was an independent predictor of plaque growth in women, but not in men, suggesting gender-specific actions of OPG in plaque growth. OPG was not associated with novel plaque formation.

Severe head injury: control of physiological variables, organ failure and complications in the intensive care unit

BACKGROUND

In patients with severe head injury, control of physiological variables is important to avoid intracranial hypertension and secondary injury to the brain. The aims of this retrospective study were to evaluate deviations of physiological variables and the incidence of extracranial complications in patients with severe head injury. We also studied if these deviations could be related to outcome.

PATIENTS AND METHODS

One hundred and thirty-three patients were included during a 5-year period (1998-2002). Deviations from treatment goals for the following physiological variables were studied: blood pressure, haemoglobin, blood sugar, serum sodium, serum albumin and temperature. Extra cerebral organ complications were also recorded as well as outcome at 6 months.

RESULTS

The median age was 32 years (range; 1-88 years). Median Glasgow Coma Scale (GCS) before intubation was 6 (range; 3-14). The frequencies of severe deviations from the desired values of the physiological variables for at least one treatment day were: hypotensive episodes (systolic BP < 90 mmHg) - 20%, anaemia (hgb < 8 g/dL) - 22%, blood glucose > 10 mmol/l - 26%, serum sodium concentration < 130 mmol/l - 10%, serum albumin < 25 g/l(-1)- 31% and hyperthermia > 39 degrees C - 24%. Pneumonia was diagnosed in 71% and Acute Lung Injury (ALI)/Adult Respiratory Distress Syndrome (ARDS) in 26% of the patients. Other complications such as severe sepsis (6%), renal failure (1.5%), a coagulation disorder (6%) and liver failure (one patient) were infrequent. Age, GCS, hypotension during the first day of treatment, elevated blood sugar and low albumin predicted an unfavourable outcome.

CONCLUSIONS

Deviations of key physiological variables and pulmonary complications were frequent in patients suffering from severe head injury. During intensive care treatment, hypotension, elevated blood sugar and hypoalbuminemia are possible independent predictors of an unfavourable outcome.

Acute spontaneous subdural haematoma after transsphenoidal surgery

Only one case of acute spontaneous subdural haematoma (ASSDH) has been reported following transsphenoidal surgery, whereas, another case of chronic SDH has been reported. We present a patient with pituitary apoplexy, who was treated by transsphenoidal surgery. 8 days postoperative he developed an ASSDH requiring immediate surgical evacuation. This case documents the third occurrence of SDH as a complication of transsphenoidal surgery and is the first report of ASSDH that required immediate surgical evacuation.

Eight year outcome after surgery for lumbar disc herniation: a comparison of reoperated and not reoperated patients

A retrospective study of 211 patients with unilateral sciatica operated on for lumbar disc herniation during 1988 and 1989 was performed in order to compare the results of reoperated patients with the results of patients operated on only once. The patients completed a standardized questionnaire in 1997 which included questions about reoperations, back and leg pain, functional status and disability pension. Outcome scores were calculated, giving values from 0 (no pain/normal function) to 100 (totally disabled). A follow-up status of 80.1% was obtained; 163 patients answered the questionnaire while six patients had died. 23.9% of the patients (n = 39) had been reoperated on. A recurrent disc herniation at the same level was suspected before the reoperation in 18.4%, but a recurrence was found in only 8.6%. 3.7% were reoperated on more than once. Outcome score was worse among "reoperated" patients (median 45.0, range 0-94) than among patients who only had the primary operation (median 10.5, range 0-81) (P < 0.001). In addition, 34.3% of the "reoperated" patients received a disability pension compared to 9.9% of the patients not reoperated on (P < 0.01). Patients reoperated upon at the same level without peroperative signs of recurrent disc herniation, had an outcome score of 53.0 (range 0-82) compared to a score of 30.0 (range 0-66) in patients with a confirmed recurrence (P < 0.05). The percentage of disability pension was 53.8% versus 9.1%, respectively, for those two groups (P < 0.05). Eight years after operation for lumbar disc herniation, the outcome was significantly worse in "reoperated" patients than in patients operated on once. In addition, reoperated patients with peroperatively confirmed recurrence of the same disc, seemed to have a better outcome than patients without peroperative signs of a recurrence.

Membrane biology: membrane-regulated transcription

The activation of membrane-bound transcription factors involves release from the membrane by proteolysis. Recent studies show that, for some proteins, cleavage is performed by the proteasome, whereas others require specific proteases.

[Long-term follow-up after surgery for lumbar disk herniation]

BACKGROUND

We wanted to evaluate long-term outcome after operation for lumbar disc herniation at a department of neurosurgery which train spinal surgeons. Both conventional and microsurgical technique were used during this period.

MATERIAL AND METHODS

Data were collected retrospectively from patient files. During 1988-89, 211 patients with lumbar disc herniation and unilateral sciatica were operated by microsurgical (n = 122) or by conventional technique (n = 89). In 1997, patients completed standardized questionnaires that included questions about pain and functional status (outcome score 0-100) and reoperations.

RESULTS

163 patients answered the questionnaire (77%). 39 patients (24%) had been reoperated. Median outcome score was 10.5 (range 0-81) in patients not reoperated, a score significantly better than the score of reoperated patients (45.0, range 0-94). There was no significant difference between patients operated by microsurgical and conventional technique.

INTERPRETATION

The frequency of reoperations was high. Outcome was satisfactory seven to nine years after surgery for lumbar disc herniation in patients not reoperated, but poor in reoperated patients. The retrospective design of our study does not allow any conclusion on whether conventional or microsurgical technique gives the best result.

Low-grade non-Hodgkin's lymphoma in northern Norway: treatment, outcome, and prognostic factors

AIM

All low-grade non-Hodgkin's lymphoma (LG-NHL) patients diagnosed and/or treated at our institution over a 10 year period were investigated with regard to treatment outcome and possible pre-treatment prognostic factors.

PATIENTS AND METHODS

During the period 1986-1995, 169 consecutively registered patients with LG-NHL were retrospectively analyzed with regard to personal, treatment, and disease- specific characteristics. The median follow-up time was 52 months (5-132 months). All patients were diagnosed histologically according to the Keil classification system. Median age was 60 years (range 27-87 years), and the male:female ratio was 1.05: 1.

RESULTS

The overall response rate was 77%, of which 66% were complete response (CR) and 11% partial response (PR). 5- and 10-year overall survival were 72% and 47%, respectively, and median overall survival was 8.3 years. 10-year overall survival for stage I, II, III, and IV were 86%, 65%, 33%, and 29%, respectively. For follicular lymphoma, 10-year survival was 52% and median survival 12.5 years. In univariate analysis, the following pre-treatment factors indicated a poor prognosis: advanced stage, general symptoms, bone marrow infiltration, poor performance status, tumor > or = 6 cm, low serum albumin, anaemia, and LDH > or = 540 U/l. In multivariate analysis, stage, performance status, tumor size, and anaemia were found to be independent prognostic factors for overall survival.

CONCLUSIONS

The treatment strategy has proved successful for most patients with localised disease. Independent prognostic indicators for survival as stage, performance status, tumor size, and anaemia may be useful guides in deciding when and how to treat.

Calcitonin and bipolar disorder: a hypothesis revisited

Double-blind trials conducted in the early 1980s showed that subcutaneous injections of salmon calcitonin in patients suffering from mania resulted in significant decreases in irritability, euphoria and hyperactivity. Although these results were promising, there were no follow-up studies in this area. A MEDLINE search into the effect of calcitonin on neuronal tissues revealed that calcitonin affects neuronal tissues in a manner similar to that of the currently accepted mood-stabilizing agents--namely by modulating intracellular second messenger signalling mechanisms, stabilizing neuronal membranes and inhibiting neuronal calcium influx. We suggest that these effects of calcitonin on neuronal tissues, combined with earlier clinical research showing its efficacy in treating the acute symptoms of mania, make calcitonin a candidate for further research in the treatment of bipolar disorder.

Comparison of haemodynamic effects during venous air infusion and after decompression in pigs

We have compared haemodynamic effects of venous gas emboli during continuous air infusion into the right atrium and after rapid decompression in pigs. Eight anaesthetized and spontaneously breathing pigs received continuous air infusion at a rate of either 0.05 ml.kg-1.min-1 (six pigs, air infusion group) or 0.10 ml.kg-1.min-1 (two pigs). Another eight pigs (decompression group) underwent a 30-min compression to 5 bar (500 kPa, absolute pressure), followed by a rapid decompression (2 bar.min-1). Haemodynamic variables were measured or calculated, and bubbles in the pulmonary artery were monitored using transoesophageal echocardiography. The results showed less variation in the maximal increase in mean pulmonary arterial pressure (BPa,pulm) during air infusion (0.05 ml.kg-1.min-1) than after decompression, although the mean maximal increase did not differ between the two groups [28.0 mmHg (3.73 kPa), 95% confidence interval (CI) 23.5-32.5, vs 32.0 mmHg (4.27 kPa), 95% CI 25.3-38.7, P = 0.3]. The BPa,pulm stabilized or decreased very slowly after peak values were reached in the air infusion group, whereas the BPa,pulm decreased rapidly during the same period in the decompression group. No significant changes in mean arterial pressure were observed during air infusion (0.05 ml.kg-1.min-1), in contrast to the rapid increase and the subsequent decrease, that appeared after decompression. Finally, the maximal bubble count was much lower in the air infusion group than in most of the pigs in the decompression group. The two pigs that received 0.10 ml.kg-1.min-1 stopped breathing after 5-min infusion, developed arterial hypotension and died.

Relationship between venous bubbles and hemodynamic responses after decompression in pigs

We present a new pig model for studying relationships between venous gas bubbles and physiologic effects during and after decompression. Sixteen pigs were anesthetized to allow spontaneous breathing. Eight of them underwent a 30-min exposure to 5 bar (500 kPa) followed by a rapid decompression to 1 bar (2 bar/min); the remaining eight served as controls. The pigs were monitored for intravascular bubbles using a transesophageal echocardiographic transducer, and bubble count in the two-dimensional ultrasound image of the pulmonary artery was used as a measure of the number of venous gas bubbles. Effects on physiologic variables of the pulmonary and the systemic circulations were either measured or estimated. We detected venous bubbles in all pigs after decompression, but the interindividual variation was large. The time course of changes in the mean pulmonary artery pressure, in the pulmonary vascular resistance, in the arterial oxygen tension, and in the pulmonary shunt fraction followed the time course of the bubble count. In contrast, such a relationship to the number of venous gas bubbles was not found for the immediate increase in mean arterial pressure and for the changes in the other variables of the systemic circulation. We conclude that the number of venous gas bubbles, as evaluated by the bubble count in the ultrasound image of the pulmonary artery, is clearly related to changes in the variables of the pulmonary circulation in this pig model.

Arterial gas bubbles after decompression in pigs with patent foramen ovale

With patent foramen ovale (PFO), thought to be a risk factor for some forms of DCS, venous bubbles may pass through the patent opening to become arterial bubbles. We exposed 14 anesthetized, spontaneously breathing pigs to air at 5 bar (500 kPa, absolute pressure) for 30 min and then rapidly decompressed at 2 bar/min to 1 bar. We measured intravascular pressures, blood gases, and, with transesophageal echocardiology, bubbles in the pulmonary artery and ascending aorta. Autopsy showed that six of the pigs had a PFO. Arterial bubbles occurred more frequently in the PFO group (in six out of six) than in the non-PFO group (in two out of eight, P < 0.01). When arterial bubbles were detected, the venous bubble count and the pulmonary artery pressure tended to be lower in pigs with PFO than in pigs without a PFO. We conclude that a PFO increases the risk of arterial bubbles after decompression.

Effects of treatment with Pluronic F-68 during continuous venous air embolism in swine

Treatment with the surface-active agent Pluronic F-68, shown to modulate the hemodynamic effects of venous air emboli (VAE) in dogs, may be useful for treatment of VAE in divers. We report on the effects of injections of Pluronic F-68 on responses to continuous air infusion in swine. Pretreatment made no significant difference in any hemodynamic or ventilatory variables, but the rise of pulmonary vascular resistance caused by air infusion was greater in surfactant-treated animals; this was also evident after a second treatment during the air infusion. The small effect of surfactant treatment in our study on swine contrasts the effects reported previously in dogs, and could be due to species-specific differences in lung physiology-anatomy, or due to difference in experimental design. We speculate that the minor changes we observed were caused by deeper penetration of the bubbles into the pulmonary arterial tree after surfactant treatment.

Paradoxical air embolism in pigs with a patent foramen ovale

Recent studies have indicated that divers with a patent foramen ovale (PFO) are at risk of developing some forms of decompression sickness. Thus, the objective of the present study was to investigate if the occurrence of paradoxical air embolism (PAE) was enhanced in pigs with a PFO compared to the occurrence in pigs without such a defect. Out of 54 pigs, 18 had a PFO (group PFO), and the other 36 composed the controls (group C). The pigs were anesthetized, mechanically ventilated, and received venous air infusion at four different rates (0.050, 0.075, 0.100, and 0.200 ml.kg-1.min-1). PAE was monitored by use of a transesophageal echocardiographic probe to detect if any arterial air bubbles were present in the left atrium or the aorta. We found that PAE appeared at a lower infusion rate in group PFO than in group C. When PAE occurred, the mean pulmonary arterial pressure and the mean arterial pressure were significantly higher in pigs with a PFO than in the control pigs. Finally, the infused air volume per kilogram of body weight in group PFO was significantly lower than that observed in group C. The results demonstrated that the risk of PAE occurring in mechanically ventilated pigs with a PFO was greater compared to the risk observed in pigs without a PFO.

Segmental aortic wall stiffness from intravascular ultrasound at normal and subnormal aortic pressure in pigs

Segmental aortic wall stiffness was calculated from intravascular ultrasound images and intravascular pressures in six pigs at normal and subnormal aortic pressures (21 sequences of pressures and areas before and after boli of intravenous nitroglycerin). The wall stiffness was expressed as the pressure-strain elastic modulus (Ep). The Ep was calculated from the formula: Ep = delta PR delta R-1 (P, pressure; R, radius) in two different ways. First from maximal and minimal values of pressure and area. Second as the slope of linear regression line of delta PR as a function of delta R from 29 simultaneous recorded pressures and images. The average Ep value for all sequences in the different segments was 0.58 +/- 0.55 10(5) Pa (Method 1) and 0.50 +/- 0.40 10(5) Pa (Method 2). Ep increased with the distance from the heart at normal aortic pressures. At subnormal aortic pressures after intravenous nitroglycerin this relationship was not so evident. At subnormal aortic pressures the calculated Ep values were significantly reduced in the lower half of the abdominal aorta. The phase lag, i.e. hysteresis, between pressure and diameter was demonstrated. Our study shows the applicability of intravascular ultrasound as a tool to evaluate arterial wall stiffness.

Effect of aminophylline on transpulmonary passage of venous air emboli in pigs

Aminophylline has been shown to dramatically reduce the filtering capacity of the lung in dogs during venous air embolism. Similarities have been pointed out between the cardiovascular and respiratory systems of the pig and of humans. We therefore wanted to find out whether aminophylline also modifies the transpulmonary spillover of microbubbles to the arterial circulation of the pig. Twenty-eight pigs were anesthetized with pentobarbital sodium and mechanically ventilated. Aminophylline was injected intravenously into 10 of the pigs before the introduction of air bubbles into the right ventricle, while the other 18 pigs served as controls. A transesophageal echocardiographic probe was used to detect eventual air bubbles in the left atrium or in the aorta. Pigs received either air infusion, at rates varying from 0.05 to 0.20 ml.kg-1.min-1, or calibrated microbubbles, 5-300 microns diam. We found that aminophylline-treated pigs did not show any change in spillover incidence compared with controls. Furthermore, in both groups the spillover during continuous air infusion seemed to be a preterminal event, because the pigs had very low arterial pressure when arterial bubbles were observed. Finally, there was an increase in mean pulmonary arterial pressure from 18 +/- 3.4 to 26 +/- 2.2 (SD) mmHg (n = 4, P less than 0.01) in aminophylline-treated pigs after a bolus injection of microbubbles (less than or equal to 50 microns, total volume less than 0.5 ml). Our results suggest that aminophylline does not modify the transpulmonary passage of microbubbles in this porcine model. In addition, it would seem that the pulmonary circulation of the pig is sensitive to very small volumes of air, when injected as microbubbles.

MRI: a method to detect minor brain damage following coronary bypass surgery?

In order to assess the occurrence of minor focal brain lesions after coronary bypass surgery, magnetic resonance imaging (MRI) was used. Nine male patients (age 42-63) with angina pectoris were investigated at 0.5 Tesla. The investigation was performed one to seven weeks prior to the operation and one month after the operation. Before surgery, the images demonstrated more than five high intensity spots in the white matter of the brain in all but two patients. No additional spots were found after operation. This pilot study indicates that it might be difficult to use MRI to detect minor parenchymal lesions after cardiopulmonary bypass surgery.

Venous air embolism in swine: transport of gas bubbles through the pulmonary circulation

The assumption that the lung is an effective filter for gas bubbles is of importance for certain occupations (e.g., divers, astronauts) as well as in the accomplishment of several medical procedures. The filtering capacity was tested in pigs by use of continuous air infusion into the right ventricle and a transesophageal echocardiographic transducer for detection of air in the left atrium. Twenty pigs, anesthetized with pentobarbital sodium and mechanically ventilated, were divided into groups that received air at infusion rates of 0.05 (group 1a, n = 7), 0.10 (group 2, n = 6), and 0.20 (group 3, n = 5) ml.kg-1.min-1. Two pigs served as controls. The breakthrough incidence was 0, 67, and 100%, respectively. Group 1a received a second infusion of 0.10 ml.kg-1.min-1 (group 1b, n = 7), and spillover of bubbles occurred in only 14% of these pigs. Infusion of gas caused a maximum increase in mean pulmonary arterial pressure (PAP) of 129 +/- 9% to 39.2 +/- 1.3 (SE) mmHg, with no significant difference between the groups. Breakthrough was observed only in animals with a dramatic reduction in mean arterial pressure and a PAP that returned to almost-normal values at spillover time. Our results suggest that the threshold value for breakthrough of air bubbles in pigs is reduced compared with that in dogs. The hemodynamic consequences at a given infusion rate are, however, greatly enhanced.

Advantages of total androgen blockade in the treatment of advanced prostate cancer

Total androgen blockade has been proposed as a better therapeutic technique than castration alone for the management of metastatic prostate cancer. This is based on the theory that links adrenal androgens to tumor growth. We have carefully examined the role of adrenal androgens in prostate cancer. Work done in our laboratory, as well as the work of many others, has demonstrated the following in regard to the role of adrenal androgens in prostate cancer: (1) The adrenal cortex secretes significant amounts of adrenal androgens into the blood. (2) Adrenal androgens are converted into dihydrotestosterone (DHT), as indicated by studies of labeled DHT recovered from prostates resected one-half hour after infusion of 3H-androstenedione or 3H-dehydroepiandrosterone sulfate into patients. We have also shown that biopsies of prostates from patients who were previously castrated may contain significant amounts of DHT, which could only be derived from adrenal androgens. (3) We have quantified DHT derived from adrenal androgens by measuring prostate DHT concentrations in castrates and in patients treated with combined gonadal and adrenal blockade. The mean difference between these two groups, 0.32 ng/g of DHT lower with combined blockade, is statistically significant and represents DHT derived from adrenal androgens. (4) We have also demonstrated that the small amounts of DHT derived from adrenal androgens may be biologically significant in stimulating prostatic epithelial cell protein synthesis in humans; others have reported similar findings in animals. (5) A review of patients in relapse after castration, who are treated with adrenal androgen blockade, indicates that approximately one out of three patients will show an objective remission based on National Prostate Cancer Project (NPCP) criteria. Despite data supporting the importance of adrenal androgens in prostate cancer, clinical trials using combined adrenal and gonadal blockade in prostate cancer have shown only modest benefit over castration. The largest and best study to date is the Southwest Oncology Group (SWOG) study, which did show a near-significant (P less than 0.065) difference between patients treated for 20 months with a luteinizing hormone-releasing hormone (LH-RH) plus flutamide compared with LH-RH alone. The difference in median time to progression was approximately 2 months between the groups. However, when one considers the fact that two out of three patients are probably not responding to the total androgen blockade, the 2 month difference may actually represent 6 or more months in a subset of one-third of patients receiving that therapy.(ABSTRACT TRUNCATED AT 400 WORDS)