Clinical safety and feasibility of a novel implantable neuroimmune modulation device for the treatment of rheumatoid arthritis: initial results from the randomized, double-blind, sham-controlled RESET-RA study

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that causes persistent synovitis, bone damage, and progressive joint destruction. Neuroimmune modulation through electrical stimulation of the vagus nerve activates the inflammatory reflex and has been shown to inhibit the production and release of inflammatory cytokines and decrease clinical signs and symptoms in RA. The RESET-RA study was designed to determine the safety and efficacy of an active implantable device for treating RA.

METHODS

The RESET-RA study is a randomized, double-blind, sham-controlled, multi-center, two-stage pivotal trial that enrolled patients with moderate-to-severe RA who were incomplete responders or intolerant to at least one biologic or targeted synthetic disease-modifying anti-rheumatic drug. A neuroimmune modulation device (SetPoint Medical, Valencia, CA) was implanted on the left cervical vagus nerve within the carotid sheath in all patients. Following post-surgical clearance, patients were randomly assigned (1:1) to active stimulation or non-active (control) stimulation for 1 min once per day. A predefined blinded interim analysis was performed in patients enrolled in the study's initial stage (Stage 1) that included demographics, enrollment rates, device implantation rates, and safety of the surgical procedure, device, and stimulation over 12 weeks of treatment.

RESULTS

Sixty patients were implanted during Stage 1 of the study. All device implant procedures were completed without intraoperative complications, infections, or surgical revisions. No unanticipated adverse events were reported during the perioperative period and at the end of 12 weeks of follow-up. No study discontinuations were due to adverse events, and no serious adverse events were related to the device or stimulation. Two serious adverse events were related to the implantation procedure: vocal cord paresis and prolonged hoarseness. These were reported in two patients and are known complications of surgical implantation procedures with vagus nerve stimulation devices. The adverse event of vocal cord paresis resolved after vocal cord augmentation injections with filler and speech therapy. The prolonged hoarseness had improved with speech therapy, but mild hoarseness persists.

CONCLUSIONS

The surgical procedures for implantation of the novel neuroimmune modulation device for the treatment of RA were safe, and the device and its use were well tolerated.

TRIAL REGISTRATION

NCT04539964; August 31, 2020.

Magnetic resonance imaging-guided focused ultrasound thalamotomy for essential tremor: 5-year follow-up results

OBJECTIVE

The objective of this study was to evaluate, at 4 and 5 years posttreatment, the long-term safety and efficacy of unilateral MRI-guided focused ultrasound (MRgFUS) thalamotomy for medication-refractory essential tremor in a cohort of patients from a prospective, controlled, multicenter clinical trial.

METHODS

Outcomes per the Clinical Rating Scale for Tremor (CRST), including postural tremor scores (CRST Part A), combined hand tremor/motor scores (CRST Parts A and B), and functional disability scores (CRST Part C), were measured by a qualified neurologist. The Quality of Life in Essential Tremor Questionnaire (QUEST) was used to assess quality of life. CRST and QUEST scores at 48 and 60 months post-MRgFUS were compared to those at baseline to assess treatment efficacy and durability. All adverse events (AEs) were reported.

RESULTS

Forty-five and 40 patients completed the 4- and 5-year follow-ups, respectively. CRST scores for postural tremor (Part A) for the treated hand remained significantly improved by 73.3% and 73.1% from baseline at both 48 and 60 months posttreatment, respectively (both p < 0.0001). Combined hand tremor/motor scores (Parts A and B) also improved by 49.5% and 40.4% (p < 0.0001) at each respective time point. Functional disability scores (Part C) increased slightly over time but remained significantly improved through the 5 years (p < 0.0001). Similarly, QUEST scores remained significantly improved from baseline at year 4 (p < 0.0001) and year 5 (p < 0.0003). All previously reported AEs remained mild or moderate, and no new AEs were reported.

CONCLUSIONS

Unilateral MRgFUS thalamotomy demonstrates sustained and significant tremor improvement at 5 years with an overall improvement in quality-of-life measures and without any progressive or delayed complications. Clinical trial registration no.: NCT01827904 (ClinicalTrials.gov).

Predictors of Outcomes After Focused Ultrasound Thalamotomy

BACKGROUND

Magnetic resonance-guided focused ultrasound thalamotomy (FUS-T) is an emerging treatment for essential tremor (ET).

OBJECTIVE

To determine the predictors of outcomes after FUS-T.

METHODS

Two treatment groups were analyzed: 75 ET patients enrolled in the pivotal trial, between 2013 and 2015; and 114 patients enrolled in the postpivotal trials, between 2015 and 2016. All patients had medication-refractory, disabling ET, and underwent unilateral FUS-T. The primary outcome (hand tremor score, 32-point scale with higher scores indicating worse tremor) and the secondary outcome variables (Clinical Rating Scale for Tremor Part C score: 32-point scale with higher scores indicating more disability) were assessed at baseline and 1, 3, 6, and 12 mo. The operative outcome variables (ie, peak temperature, number of sonications) were analyzed. The results between the 2 treatment groups, pivotal and postpivotal, were compared with repeated measures analysis of variance and adjusted for confounding variables.

RESULTS

A total of 179 patients completed the 12-mo evaluation. The significant predictors of tremor outcomes were patient age, disease duration, peak temperature, and number of sonications. A greater improvement in hand tremor scores was observed in the postpivotal group at all time points, including 12 mo (61.9% ± 24.9% vs 52.1% ± 24.9%, P = .009). In the postpivotal group, higher energy was used, resulting in higher peak temperatures (56.7 ± 2.5 vs 55.6 ± 2.8°C, P = .004). After adjusting for age, years of disease, number of sonications, and maximum temperature, the treatment group was a significant predictor of outcomes (F = 7.9 [1,165], P = .005).

CONCLUSION

We observed an improvement in outcomes in the postpivotal group compared to the pivotal group potentially reflecting a learning curve with FUS-T. The other associations of tremor outcomes included patient age, disease duration, peak temperature, and number of sonications.

Effect of citicoline on functional and cognitive status among patients with traumatic brain injury: Citicoline Brain Injury Treatment Trial (COBRIT)

CONTEXT

Traumatic brain injury (TBI) is a serious public health problem in the United States, yet no treatment is currently available to improve outcome after TBI. Approved for use in TBI in 59 countries, citicoline is an endogenous substance offering potential neuroprotective properties as well as facilitated neurorepair post injury.

OBJECTIVE

To determine the ability of citicoline to positively affect functional and cognitive status in persons with complicated mild, moderate, and severe TBI.

DESIGN, SETTING, AND PATIENTS

The Citicoline Brain Injury Treatment Trial (COBRIT), a phase 3, double-blind randomized clinical trial conducted between July 20, 2007, and February 4, 2011, among 1213 patients at 8 US level 1 trauma centers to investigate effects of citicoline vs placebo in patients with TBI classified as complicated mild, moderate, or severe.

INTERVENTION

Ninety-day regimen of daily enteral or oral citicoline (2000 mg) or placebo.

MAIN OUTCOME MEASURES

Functional and cognitive status, assessed at 90 days using the TBI-Clinical Trials Network Core Battery. A global statistical test was used to analyze the 9 scales of the core battery. Secondary outcomes were functional and cognitive improvement, assessed at 30, 90, and 180 days, and examination of the long-term maintenance of treatment effects.

RESULTS

Rates of favorable improvement for the Glasgow Outcome Scale-Extended were 35.4% in the citicoline group and 35.6% in the placebo group. For all other scales the rate of improvement ranged from 37.3% to 86.5% in the citicoline group and from 42.7% to 84.0% in the placebo group. The citicoline and placebo groups did not differ significantly at the 90-day evaluation (global odds ratio [OR], 0.98 [95% CI, 0.83-1.15]); in addition, there was no significant treatment effect in the 2 severity subgroups (global OR, 1.14 [95% CI, 0.88-1.49] and 0.89 [95% CI, 0.72-1.49] for moderate/severe and complicated mild TBI, respectively). At the 180-day evaluation, the citicoline and placebo groups did not differ significantly with respect to the primary outcome (global OR, 0.87 [95% CI, 0.72-1.04]).

CONCLUSION

Among patients with traumatic brain injury, the use of citicoline compared with placebo for 90 days did not result in improvement in functional and cognitive status.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00545662.

Use of the LandmarXtrade mark Surgical Navigation System in Lateral Skull Base and Temporal Bone Surgery

Despite the widespread availability of surgical navigation devices, their use in lateral skull base and temporal bone surgery has been limited. Problems with current systems include difficulty of use and inadequate accuracy. We present a series of cases using the LandmarXtrade mark surgical navigation system as an adjunct for lateral skull base and temporal bone procedures. This infrared emitting diodes (IRED)-driven system has a post that carries the IREDs and bypasses the need to place the patient in a Mayfield head holder. This configuration allows greater mobility of the surgical field. Registration of the patient can include a combination of fiducial and anatomic landmarks that significantly increase accuracy compared to fiducial calibration alone. We introduced the use of the lateral process of the malleus as a landmark, thereby increasing accuracy within the temporal bone to a range of 0.9 to 1.5 mm. We used the system on encephaloceles, glomus tumors, meningiomas, and schwannomas, and revision surgery for chronic otitis media. It decreased operating time, allowed more effective use of "keyhole" approaches, and increased safety. As the availability and flexibility of these systems increase, their use should become the standard of care in revision temporal bone and lateral skull base procedures.

THE EFFECT OF CORTICOSTERONE AND RELATED COMPOUNDS ON THE RENAL EXCRETION OF ELECTROLYTES

The sodium and chloride retaining effect of suprarenal cortical extracts and of crystalline compounds derived from the suprarenal cortex parallels their effectiveness in maintaining suprarenalectomized dogs. All of the active compounds thus far studied produce a potassium diuresis when injected into normal dogs. The injection of a synthetic compound, desoxy-corticosterone acetate, produced in normal dogs a very marked sodium and chloride retention and a potassium diuresis. In a suprarenalectomized dog desoxy-corticosterone acetate was substituted successfully for suprarenal cortical extract.

The citicoline brain injury treatment (COBRIT) trial: design and methods

Traumatic brain injury (TBI) is a major cause of death and disability. In the United States alone approximately 1.4 million sustain a TBI each year, of which 50,000 people die, and over 200,000 are hospitalized. Despite numerous prior clinical trials no standard pharmacotherapy for the treatment of TBI has been established. Citicoline, a naturally occurring endogenous compound, offers the potential of neuroprotection, neurorecovery, and neurofacilitation to enhance recovery after TBI. Citicoline has a favorable side-effect profile in humans and several meta-analyses suggest a benefit of citicoline treatment in stroke and dementia. COBRIT is a randomized, double-blind, placebo-controlled, multi-center trial of the effects of 90 days of citicoline on functional outcome in patients with complicated mild, moderate, and severe TBI. In all, 1292 patients will be recruited over an estimated 32 months from eight clinical sites with random assignment to citicoline (1000 mg twice a day) or placebo (twice a day), administered enterally or orally. Functional outcomes are assessed at 30, 90, and 180 days after the day of randomization. The primary outcome consists of a set of measures that will be analyzed as a composite measure using a global test procedure at 90 days. The measures comprise the following core battery: the California Verbal Learning Test II; the Controlled Oral Word Association Test; Digit Span; Extended Glasgow Outcome Scale; the Processing Speed Index; Stroop Test part 1 and Stroop Test part 2; and Trail Making Test parts A and B. Secondary outcomes include survival, toxicity, and rate of recovery.

A right atrial mass: thrombus, tumour or other?

A 71-year-old man was admitted with right lower lobe pneumonia, right-sided pleural effusion and congestive cardiac failure. He had been well until a left occipito-parietal embolic stroke (documented on computed tomography; CT) 2 years previously. Chronic atrial fibrillation and hypertension were noted and he was commenced on digoxin, warfarin and amlodipine. A transthoracic echocardiogram showed normal left ventricular contractility, mild mitral regurgitation and a severely dilated left atrium. He made a full neurological recovery.

Gamma knife radiosurgery for the treatment of brain metastases

One hundred and ninety-three patients with brain metastases from various primary sites received Gamma Knife radiosurgery (GKR) from July 1992 to August 1997 and were reviewed to evaluate their clinical outcome. Survival follow-up was available on 173 patients. Whole-brain radiation therapy was also administered to 148 of these patients. The median survival was 13.1 months from initial detection of brain metastases, and 7.5 months from GKR. Univariate and multivariate analyses were performed to determine prognostic factors that influenced survival following GKR. Enhanced survival is observed in patients with radiosensitive tumor types, supratentorial tumor, history of brain tumor resection, controlled primary site, and absent extracranial metastases. Local lesion control was obtained in 82% of the patients according to their last follow-up MRI scan. GKR is an effective means of treating patients with brain metastases.

Analytical ultracentrifugation in a Gibbsian perspective

The analytical ultracentrifuge has come into new intensive use following complete instrumental redesign and the use of advanced computer technologies for the analysis and interpretation of experimental results. Major attention is now devoted to the evaluation of interactions between similar and dissimilar biological macromolecules in dilute and concentrated systems. Electrostatically charged biological solute systems additionally comprise low molecular weight charged and non-charged cosolvents. Solvent/cosolvent interactions, insufficiently considered in most current analytical ultracentrifugation analyses, may quantitatively affect solute/solute interactions. For comprehensive analysis the Svedberg derivation considering a buoyant molar mass (1 - rho0 partial specific volume)M2 and valid at vanishing solute concentration for strictly two component systems only, should be replaced, following classical thermodynamic analysis, by the ratio (delta rho/delta c2)(mu)/d pi/dc2 of the density increment at constant chemical potential of diffusible cosolvents, to the derivative of the osmotic pressure with solute concentration. Disregard of the solvent/cosolvent and solute/cosolvent interactions should be avoided.

Robotics in child neurosurgery

We felt there was a need for a new device with "minimal invasive" tracking hardware, to be used in image-guided neurosurgery, and the system we designed to fill this need is now presented. It combines precision of movement, stability and self-positioning capabilities together with optically tracked registration and procedural control within the structure of a surgical microscope. The results are reduced setup time and minimal "distraction" from the procedure itself, factors of special relevance in child neurosurgery. The system is composed of a six-axis industrial robot suitable for use in the operating room, carrying a surgical microscope. Three progressive scan-synchronized infrared cameras mounted around the lenses of the scope are used to register the patient's position and track surgical instruments with reference to the registered space. Orientation of the microscope during surgery is obtained with a six-axis joystick used as a microscope handle. The system has been clinically used in 14 cases, and it has proven itself to be reliable, providing the expected performance advantages. The implementation of a tracked ultrasound or endoscope intraoperative imaging source is also described.

Coronary artery calcium evaluation by electron beam computed tomography and its relation to new cardiovascular events

Electron beam computed tomography is widely used to screen for coronary artery calcium (CAC). We evaluated the relation of CAC to future cardiovascular disease events in 926 asymptomatic persons (735 men and 191 women, mean age 54 years) who underwent a baseline electron beam computed tomographic scan. All subjects included in this report returned a follow-up questionnaire 2 to 4 years (mean 3.3) after scanning, inquiring about myocardial infarction, stroke, and revascularizations. Sixty percent of men and 40% of women had a positive scan at baseline. Twenty-eight cardiovascular events occurred and were confirmed by blinded medical record review. The presence of CAC (a total calcium score of >0) and increasing score quartiles were related to the occurrence of new myocardial infarction (p <0.05), revascularizations (p <0.001), and total cardiovascular events (p <0.001). Those with scores at or above the median (score of 5) had a relative risk of 4.5 (p <0.01) for new events. From Cox regression models, adjusted for age, gender, and coronary risk factors, the relative risks for those with scores of 81 to 270 and -271 (compared with 0) for cardiovascular events were 4.5 (p <0.05) and 8.8 (p <0.001), respectively. These data support previous reports showing CAC to be a modest predictor of future cardiovascular events.

Probing protein-sugar interactions

We have investigated the partial specific volumes (2) (ml/g), hydration, and cosolvent interactions of rabbit muscle aldolase by equilibrium sedimentation in the analytical ultracentrifuge and by direct density increment (partial differential/partial differentialc(2))(mu) measurements over a range of sugar concentrations and temperature. In a series of sugars increasing in size, glucose, sucrose, raffinose, and alpha-cyclodextrin, (partial differential/ partial differentialc(2))(mu) decreases linearly with the solvent density rho(0). These sugar cosolvents do not interact with the protein; however, the interaction parameter B(1) (g water/g protein) mildly increases with increasing sugar size. The experimental B(1) values are smaller than values calculated by excluded volume (rolling ball) considerations. B(1) relates to hydration in this and in other instances studied. It decreases with increasing temperature, leading to an increase in (2) due to reduced water of hydration electrostriction. The density increments (partial differential/ partial differentialc(2))(mu), however, decrease in concave up form in the case of glycerol and in concave down form for trehalose, leading to more complex behavior in the case of carbohydrates playing a biological role as osmolytes and antifreeze agents. A critical discussion, based on the thermodynamics of multicomponent solutions, is presented.

Expression of nicotinic acetylcholine receptor subunits in the cerebral cortex in Alzheimer's disease: histotopographical correlation with amyloid plaques and hyperphosphorylated-tau protein

Impairment of cholinergic transmission and decreased numbers of nicotinic binding sites are well-known features accompanying the cognitive dysfunction seen in Alzheimer's disease (AD). In order to elucidate the underlying cause of this cholinoceptive dysfunction, the expression of two pharmacologically different nicotinic acetylcholine receptor (nAChR) subunits (alpha4, alpha7) was studied in the cerebral cortex of Alzheimer patients as compared to controls. Patch-clamp recordings of 14 dissociated neurons of control cortices showed responses suggesting the existence of alpha4- and alpha7-containing functional nAChRs in the human cortex. In cortices of Alzheimer patients and controls, the pattern of distribution and the number of alpha4 and alpha7 mRNA-expressing neurons were similar, whereas at the protein level a decrease in the density of alpha4- and alpha7-expressing neurons of approximately 30% was observed in Alzheimer patients. The histotopographical correlation of nAChR expression with accompanying pathological changes, e.g. accumulation of hyperphosphorylated-tau (HP-tau) protein and beta-amyloid showed that neurons in the vicinity of beta-amyloid plaques bore both nAChR transcripts. Neurons heavily labelled for HP-tau, however, expressed little or no alpha4 and alpha7 mRNA. These results point to an impaired synthesis of nAChRs on the protein level as a possible cause of the cholinoceptive deficit in AD. Further investigations need to elucidate whether interactions of HP-tau with nAChR mRNA, or alterations in the quality of alpha4 and alpha7 transcripts give rise to decreased protein expression at the level of individual neurons.

Birth of the macromolecule

The science of chemistry has made considerable advances over the last few hundred years in the characterization of "small" molecules which can be purified and studied by melting, distillation, crystallization and solubility in various liquids. When the study of "large" natural and biological molecules, limited in these properties, rose in significance at the turn of the century, it was first attempted to explain their properties by the concepts of colloid chemistry of aggregation and complex formation. The struggle for the acceptance of the concept of the natural or biological covalently bonded macromolecule, as recalled by Herman Mark, is one of the interesting chapters in recent science history. A specific phase in the establishment of the macromolecular concept centered around the development by The Svedberg of the analytical ultracentrifuge, a versatile tool of highly practical and profound thermodynamic significance.

Human microglia activate lymphoproliferative responses to recall viral antigens

The capacity of adult human microglia to activate memory T-lymphocyte responses to recall viral antigens in autologous peripheral blood lymphocytes (PBL) was examined using measles and influenza viruses. Microglia and peripheral blood macrophages were isolated form 6 patients who underwent surgical brain biopsies. Microglial cultures readily expressed high levels of HLA class II molecules under basal culture conditions. However, compared to macrophages, microglia appeared to express much lower levels of CD45, a phenotype that has been associated with the ability of rat brain macrophage/microglia to present antigen. PBL were depleted of macrophages (D-PBL) and the efficacy of the depletion was assessed by a reduction in the T-cell response to concanavalin A. D-PBL were reconstituted with macrophages, microglia, or in some cases microglia pretreated with interferon-gamma (IFN gamma). It was observed that microglia were as efficient as macrophages in presenting viral antigens. Pretreatment of microglia with IFN gamma did not enhance further antigen presentation. Oligodendrocytes which lack constitutive or inducible HLA class II molecules failed to present viral antigens. The results have implications of the direct function of microglia as perpetuators and possibly initiators of immune responses to virus infection in the central nervous system compartment.

Radiosurgery for cerebral arteriovenous malformations: assessment of early phase magnetic resonance imaging and significance of gadolinium-DTPA enhancement

PURPOSE

To evaluate the initial changes within the nidus of arteriovenous malformations (AVMs) and to assess the reaction to the brain tissue surrounding AVMs after radiosurgery by serial magnetic resonance (MR) imaging.

METHODS AND MATERIALS

Twenty-one patients, treated using 60Co gamma knife unit with cerebral AVMs, were retrospectively evaluated. Forty-seven follow-up MR images of the 21 patients were performed including 10 patients with two or more serial gadolinium enhanced studies (Gd-MR). Two or more sequential MR angiographies (MRA) were obtained in 13 patients. Three-dimensional (3D) time-of-flight MRA and two-dimensional (2D) phase contrast MRA were used in 13 patients for evaluating the flow changes of AVMs. The follow-up period after radiosurgery ranged from 3 to 30 months (average 10.8 months) and the interval time of MRI ranged from 34 days to 13 months (average 4.9 months).

RESULTS

Reduction of nidus size was observed in 14 of 21 patients (67%) between 4 to 13 months on spin echo (SE) images. Complete obliteration was observed on SE images in 4 of these 14 patients; three were confirmed by conventional angiography. New hyperintense areas surrounding the nidus on T2s-weighted images (T2WI) developed in 9 of the 14 patients who showed nidus reduction between 5 to 17 months after radiosurgery; in three patients, size of the hyperintense area started to decrease between 6 to 7 months after its appearance. Probable radiation necrosis of pons developed in one patient 26 months after radiosurgery. The irradiated area within the AVM nidus was significantly enhanced in 8 of the 10 patients who underwent Gd-MR. The degrees of enhancement within the nidus increased with time in 7 of the 10 patients. Overall, total enhancement of irradiated areas was observed in four of the 10 patients; in three of the four, the enhancement decreased in size and degree, indicating nidus reduction. In three patients who had a partial volume irradiation within the nidus, the enhancing areas corresponded with the exact portions of irradiated volume. The nidus reduction was observed in 7 of the 13 patients on MRA during 5 to 13 months after radiosurgery. MRA was more useful compared to SE images in four of the seven patients in evaluating the size change of AVM nidus, feeding arteries, and draining veins.

CONCLUSION

Magnetic resonance imaging and MRA were useful in assessing the progress of nidus reduction. T2-weighted imaging was sensitive to radiation-induced reaction in and around the AVM nidus. The enhancement within the AVM nidus on Gd-MR may represent the initial sign of nidus reduction and demonstrates the exact location of irradiation in the nidus. The changes of the enhancement pattern are presumed to represent the processes of nidus reduction and irradiated reaction within the AVM nidus.

Life in unusual environments: progress in understanding the structure and function of enzymes from extreme halophilic bacteria

Extreme halophilic archaea are saturated with salt and the intracellular electrolyte concentration exceeds that of the extracellular environment. Enzymes and other proteins from extreme halophilic archaea have been purified for many years and studied by biochemical and biophysical solution methodologies. They are active and stable at multimolar salt concentrations and denature below 2 to 3 M NaCl or KCl. Adaptation to these high concentrations of salt, genetic and evolutionary aspects, and the possibility of biotechnological applications are problems of considerable interest. Since the status of this fascinating field of research was reviewed in 1992, malate dehydrogenase from Haloarcula marismortui, now known to be a tetramer, was sequenced, its gene was cloned and expressed in active form, and its physical properties were redefined. A single mutation of Arg100 (in the enzyme active site) to Gln switched the enzyme specificity from malate to lactate dehydrogenase. Recent determination of its molecular structure by X-ray crystallography (O. Dym et al., in press) provides an exciting basis for the understanding of the structure and function of extreme halophilic enzymes. A major problem which so far has not been tackled in the study of extreme halophilic archaea is the understanding of protein nucleic acid interactions which are essential for the performance of biological function. Whereas the stability and activity of enzymes and other proteins can be modified to perform at high salt concentrations by use of currently known structural concepts, the existence of meaningful protein nucleic acid interactions in physiological concentrations of 4 to 5 M KCl constitutes an unsolved enigma worth intensive investigation.

Robot-assisted microscope for neurosurgery

We describe the implementation of a robotic arm connected to a neurosurgical operative microscope. A force feedback sensor drives the motors of the arm in response to the positioning of the microscope by the surgeon. Computer graphic techniques allow tracking of the current position of the microscope within the volumetric reconstruction of the brain. The integration of the prototype into the neurosurgical operating room is currently being evaluated. Preliminary comments on this experimental phase are offered.

Protein and nucleic acid hydration and cosolvent interactions: establishment of reliable baseline values at high cosolvent concentrations

Hydration and cosolvent interactions of biological macromolecules can be derived, subject to excluded volume corrections, from studies of density increments at constant chemical potentials of diffusible solutes through a semipermeable membrane. In addition to precision density determinations of solutions dialyzed to equilibrium, the analytical ultracentrifuge, static and dynamic light and small angle X-ray and neutron scattering, and combined pairwise use of, for instance, ultracentrifugation and neutron scattering, considerably strengthen the experimental analysis and its interpretation. We have examined hydration of bovine serum albumin (BSA) in the native and denatured states, and binding of the denaturant guanidinium chloride (GdmCl) to the latter form; hydration of DNA and interaction with NaCl and CsCl; revised values of the halophilic malate dehydrogenase (hMDH) tetramer hydration and 'binding' of salts; probing of nucleosome core particle hydration as distinct from and additionally to the evaluation of volume exclusion (holes), by use of variously sized sugar related probes. Conclusions presented are compared to results from precision calorimetry and from X-ray crystallography structures, whenever applicable, and comparisons made with alternative interpretations and experimental approaches.

Extracellular human T-cell lymphotropic virus type I Tax protein induces cytokine production in adult human microglial cells

Tropical spastic paraparesis (HAM/TSP) is caused by human T-cell lymphotropic virus type I (HTLV-I) infection. Although the virus infects T cells in vivo and is capable of infecting microglia in vitro, the inflammatory demyelination has not been linked to virus in central nervous system tissue. Thus, indirect mechanisms (e.g., cytokines) could be involved in demyelination and inflammation. The ability of HTLV-I Tax protein to induce tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 in primary adult human microglia and peripheral blood macrophages (PBMs) was examined by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction (RT-PCR). Tax (20 ng/ml) induced TNF-alpha in microglia (from undetectable or low basal levels to 215-1,075 pg/ml, mean 576 +/- 375 pg/ml, n = 4) and in PBMs (70-1,900, mean 646 +/- 844 pg/ml, n = 4). This induction was dose dependent, Tax specific, and maximal at 8 hours after stimulation. IL-6 levels in microglia increased from a basal level of 368 +/- 194 to 664 +/- 270 pg/ml 24 hours after Tax stimulation. In contrast, IL-1 beta levels were modestly induced (< or = 26 pg/ml). An increase in mRNA levels of the three cytokines was observed by semiquantitative RT-PCR (TNF-alpha = 28-fold; IL-6 = 5.6-fold; IL-1 beta = 3.6-fold). Thus, in HAM/TSP, extracellular Tax released from infiltrating T cells could induce cytokine release by microglia and contribute to demyelination and inflammation in the absence of detectable virus.

Coronary calcium and atherosclerosis by ultrafast computed tomography in asymptomatic men and women: relation to age and risk factors

We evaluated 675 men and 190 women who had no symptoms or history of clinical CHD, to determine the prevalence and risk factor correlates of CAC deposits as a marker of atherosclerosis. Measurements were taken noninvasively by ultrafast CT. The presence and extent of CAC deposits as measured by ultrafast CT was determined in all subjects, who also received personal and family medical history and risk factor questionnaire. The prevalence of CAC deposits increased significantly with age, ranging from 15% and 30% in men and women, respectively, < 40 years of age to 93% and 75% in those aged > or = 70 years. Prevalence and total score also increased by the number of risk factors present, although in those aged > 60 years a high prevalence (> 80% in men) of calcium was present regardless of the presence of risk factors. In multiple logistic regression, age, male gender, hypertension, diabetes, hypercholesterolemia, and obesity were independently associated with CAC deposits. These results suggest a high prevalence of atherosclerosis with increasing age and the presence of risk factors in men and women who have no symptoms. Studies to determine the prognostic value of CAC in individuals with no symptoms are needed to determine which populations may benefit most from CAC deposit screening.

Detection of coronary artery calcium by ultrafast computed tomography and its relation to clinical evidence of coronary artery disease

Ultrafast computed tomography (CT) was used to evaluate the relation of coronary artery calcium, a marker of atherosclerosis, with a reported history of coronary artery disease (CAD) in 928 men and 290 women (mean age 53 +/- 10 years; 11% with previous CAD). Total calcium score was calculated as the sum of each lesion-specific score, calculated as the product of pixel area and density > 130 Hounsfeld units. Total score was 3 to 6 times greater (p < 0.01) and the probability of coronary artery calcium 30 to 40% greater (p < 0.01) in patients with a reported history of myocardial infarction, positive angiography, bypass surgery or angioplasty. From score cutoffs ranging from 1 to 500 for defining calcium, a negative test was accurate 93 to 98% of the time in ruling out CAD, whereas specificity increased from 43 to 93%; however, sensitivity decreased from 92 to 42%. A score cutoff of 50 showed modest sensitivity (78%) and specificity (71%); however, the predictive value for CAD from a positive test remained low (< or = 40%), regardless of score cutoff. From multiple logistic regression, total score was also an independent indicator of CAD after considering any effects due to age, sex and other CAD risk factors. Further study is needed to document the long-term prognostic use of coronary calcium screening, including criteria that best project future risk of CAD.

Effect of positive supercoiling on DNA compaction by nucleosome cores

We have used the analytical ultracentrifuge to measure the ability of histone octamers to compact DNA as a function of DNA supercoiling. Plasmid DNA (3.25 kb) was prepared at various linking numbers (delta Lk), ranging from -35 to +8. Relaxed plasmid (delta Lk = 0) was the least compact. We reconstituted a fixed number of nucleosome cores (either 11 or 13) on these DNAs. The dependence of the frictional coefficient of delta Lk showed that the reconstitute with an initial number of negative supercoils equal to the number of nucleosome cores was the least compact, as expected if each nucleosome core formed requires the constraint of one negative supercoil, resulting in relaxed linker DNA. With DNAs containing an initial number of negative supercoils unequal to the number of nucleosome cores, reconstitutes contained either negative or positive unconstrained supercoils. Reconstitutes with the same number of unconstrained supercoils, whether positive or negative, have similar frictional coefficients and are, therefore, compacted to similar degrees. We conclude that nucleosome cores compact positively and negatively supercoiled DNA equally well. Thus, nucleosome cores formed on positively supercoiled DNA with a superhelical density as high as +0.07 are not significantly unfolded.

Cloning, sequencing, and expression in Escherichia coli of the gene coding for malate dehydrogenase of the extremely halophilic archaebacterium Haloarcula marismortui

The gene coding for the enzyme malate dehydrogenase (MDH) of the extremely halophilic archaebacterium Haloarcula marismortui was isolated and sequenced. The enzyme is composed of 303 amino acids, and its molecular mass is 32,638 Da. The deduced amino acid sequence of the enzyme was found to be more similar to the sequence of L-lactate dehydrogenase (L-LDH) from various sources than to the sequence of other MDHs. The structural gene was cloned in the Escherichia coli expression vector pET11a, and large amounts of a soluble but inactive form of the enzyme were produced upon its induction. Activation of the enzyme was obtained by increasing the salt concentration to 3 M NaCl. The recombinant protein was purified to homogeneity and shown to be indistinguishable from the native enzyme isolated from halobacteria. These findings present the first example of the successful expression of a halobacterial gene coding for a soluble protein in Escherichia coli and its recovery as a functional enzyme. Site-directed mutagenesis was employed to modify Arg100 on the enzyme to Gln. This modification produced an enzyme that has considerably higher specificity for pyruvate (the substrate of L-LDH) than for oxaloacetate (the substrate of MDH). The mutation also caused a modification in the relative activities of the enzyme at different salt concentrations. The greater similarity of the amino acid sequence of the halobacterial MDH to that of L-LDHs than to that of MDHs sheds light on the molecular evolution of these enzymes.

Risk factor correlates of coronary calcium as evaluated by ultrafast computed tomography

Coronary artery calcium is invariably associated with atherosclerosis and has been linked to an increased risk of coronary events. Ultrafast computed tomography (CT) was recently used to document the presence and relative quantity of coronary calcium. The use of the self-reported coronary risk factors to identify persons with coronary calcium as documented by ultrafast CT screening was examined in 458 men and 139 women aged 26 to 81 years (88% asymptomatic). All subjects underwent ultrafast CT scanning, and received a questionnaire and underwent an interview regarding medical and risk factor history. Total calcium score was calculated as the sum of lesion-specific scores, each calculated as the product of density > or = 130 Hounsfield units and area > or = 0.51 mm2. The prevalence of coronary calcium increased significantly (p < 0.01) by age group, and the greater the number of risk factors present, the greater the likelihood of calcium. From multiple logistic regression, age (p < 0.01), male sex (relative risk [RR] 3.03; p < 0.01), and history of smoking (RR 1.85; p < 0.01) and hypertension (RR 1.65; p < 0.05) were independently associated with the probability of detectable calcium. Among asymptomatic subjects, an association with hypercholesterolemia was also seen (RR 1.56; p < 0.05). The results demonstrate that cardiovascular risk factors can help in identifying the likelihood of coronary calcium.

The diagnosis of head injury requires a classification based on computed axial tomography

The introduction of structural imaging of the brain by computed tomography (CT) scans and magnetic resonance imaging (MRI) has further refined classification of head injury for prognostic, diagnosis, and treatment purposes. We describe a new classification scheme to be used both as a research and a clinical tool in association with other predictors of neurologic status.

Effects of chemical stimulation of the subfornical organ on metabolic activity of the hypothalamo-neurohypophysial system in rats

Topical stimulation of the subfornical organ (SFO) with angiotensin II (ANG II) or acetylcholine (ACh) increased blood pressure, water intake, and the activity of the hypothalamo-neurohypophysial system (HNS). The pressor and drinking responses were higher and the metabolic activity of the HNS, measured with the [14C]deoxyglucose (DG) method, was lower with ANG-II than with ACh. Glucose utilization in the neural lobe increased by 165% with ACh as opposed to 65% with ANG II. These results demonstrate the ANG II and ACh mobilize differentially the mechanisms increasing blood pressure, drinking responses, and the activity of the HNS.

Extracellular Ca2(+)-dependent inducible alkaline phosphatase from extremely halophilic archaebacterium Haloarcula marismortui

When starved of inorganic phosphate, the extremely halophilic archaebacterium Haloarcula marismortui produces the enzyme alkaline phosphatase and secretes it to the medium. This inducible extracellular enzyme is a glycoprotein whose subunit molecular mass is 160 kDa, as estimated by sodium dodecyl sulfate-gel electrophoresis. The native form of the enzyme is heterogeneous and composed of multiple oligomeric forms. The enzymatic activity of the halophilic alkaline phosphatase is maximal at pH 8.5, and the enzyme is inhibited by phosphate. Unlike most alkaline phosphatases, the halobacterial enzyme requires Ca2+ and not Zn2+ ions for its activity. Both calcium ions (in the millimolar range) and NaCl (in the molar range) are required for the stability of the enzyme.

Halophilic proteins and the influence of solvent on protein stabilization

Competition between protein-solvent and protein-protein interactions is arguably the most important contributing factor to polypeptide folding in general. A study of halophilic proteins, correlating their stability and solution structures in different conditions, focuses on the effects of a high salt solvent. A mechanism is proposed to explain how these proteins have adapted to such an extreme environment.

Thermodynamics and the structure of biological macromolecules. Rozhinkes mit mandeln

In this review, I will discuss the role of thermodynamics in both the determination and evaluation of the structure of biological macromolecules. The presentation relates to the historical context, state-of-the-art and projection into the future. Fundamental features relate to the effect of charge, exemplified in the study of synthetic and natural polyelectrolytes. Hydrogen bonding and water structure constitute basic aspects of the medium in which biological reactions occur. Viscosity is a classical tool to determine the shape and size of biological macromolecules. The thermodynamic analysis of multicomponent systems is essential fo the correct understanding of the behavior of biological macromolecules in solution and for the evaluation of results from powerful experimental techniques such as ultracentrifugation, light, X-ray and neutron scattering. The hydration, shape and flexibility of DNA have been studied, as well as structural transitions in nucleosomes and chromatin. A particularly rewarding field of activity is the study of unusual structural features of enzymes isolated from the extreme halophilic bacteria of the Dead Sea, which have adapted to saturated concentrations of salt. Future studies in various laboratories will concentrate on nucleic-acid--protein interactions and on the so-called 'crowding effect', distinguishing the behavior in bacteria, or other cells, from simple test-tube experiments.

Arteriographic ablation of cervical parathyroid adenomas

In some cases of primary hyperparathyroidism, in particular where neck exploration has been unsuccessful, an alternative to surgical therapy may be desirable. We studied the acute and chronic metabolic effects of attempted angiographic destruction by angiographic contrast infusion of solitary parathyroid adenomas in 18 patients with symptomatic disease. Fourteen patients had failed prior surgery; 4 patients had not undergone prior surgery but were extremely high surgical risks. Cervical adenomas were present in 17 of 18 subjects; mediastinal adenoma in 1 of 18. Sixteen patients underwent selective parathyroid venous catheterization, which facilitated subsequent arteriographic localization. Selective arteriographic localization and attempted angiographic ablation were performed in all subjects with standard contrast, renografin-60. Laboratory studies, including serum calcium and PTH, were frequently performed before and after attempted angiographic parathyroid ablation. In all patients serum calcium fell to normal or subnormal levels within 48 h of attempted ablation. Prolonged follow-up (mean, 35.1 months) revealed that ablation was curative in 12 of 18 (sustained normocalcemia) and partially effective in 1 of 18 patients. For the entire group serum calcium fell from 3.14 +/- 0.07 at presentation to 2.42 +/- 0.07 mmol/L at the end of follow-up (or before surgery in unsuccessful cases; P less than 0.001). In 4 of 5 failed cases hypercalcemia recurred within 2 weeks. All 5 failed cases underwent curative surgery, aided by accurate localization achieved during angiographic procedure. Several transient complications and 1 case of permanent hypoparathyroidism were noted. We conclude that angiographic ablation of cervical parathyroid adenomas can be considered as an extension of diagnostic angiographic procedures in selected cases of primary hyperparathyroidism who have failed prior surgery of possibly in rare cases where surgery is contraindicated.