Patient-specific analysis of the relationship between the volume of tissue activated during DBS and verbal fluency

Deep brain stimulation (DBS) for the treatment of advanced Parkinson's disease involves implantation of a lead with four small contacts usually within the subthalamic nucleus (STN) or globus pallidus internus (GPi). While generally safe from a cognitive standpoint, STN DBS has been commonly associated with a decrease in the speeded production of words, a skill referred to as verbal fluency. Virtually all studies comparing presurgical to postsurgical verbal fluency performance have detected a decrease with DBS. The decline may be attributable in part to the surgical procedures, yet the relative contributions of stimulation effects are not known. In the present study, we used patient-specific DBS computer models to investigate the effects of stimulation on verbal fluency performance. Specifically, we investigated relationships of the volume and locus of activated STN tissue to verbal fluency outcome. Stimulation of different electrode contacts within the STN did not affect total verbal fluency scores. However, models of activation revealed subtle relationships between the locus and volume of activated tissue and verbal fluency performance. At ventral contacts, more tissue activation inside the STN was associated with decreased letter fluency performance. At optimal contacts, more tissue activation within the STN was associated with improved letter fluency performance. These findings suggest subtle effects of stimulation on verbal fluency performance, consistent with the functional nonmotor subregions/somatotopy of the STN.

Prophylactic low dose ketamine and ondansetron for prevention of shivering during spinal anaesthesia

BACKGROUND

Perioperative shivering is a common problem during anaesthesia. Apart from physical warming many drugs have also been used for prevention of shivering. Ketamine has been used for preventing shivering during anaesthesia in doses of 0.5 to 0.75mg kg(-1), but even these doses causes too much sedation and hallucination. Ondansetron (8 mg) has been recently evaluated for its perioperative antishivering effect in patients under anaethesia. Present study was conducted to evaluate the efficacy and safety of low dose Ketamine (0.25mg kg(-1)) and Ondansetron (4 mg) for prevention of shivering during spinal anaesthesia. PATIENTS #ENTITYSTARTX00026;

METHODS

Total 120 patients undergoing lower abdominal surgery under spinal anaesthesia were included. 3ml of hyperbaric bupivacaine 0.5% was used for spinal anaesthesia. After intrathecal injection, the patients were randomly divided in 3 groups of 40 each who received Ketamine 0.25mg kg(-1)or Ondansetron 4mg IV or Saline. Vitals, temperature and shivering scores were recorded every 5 minutes. Side effects i.e. hypotension, nausea and vomiting, sedation and hallucinations were also recorded.

RESULTS

Fall in temperature was more significant in saline and ondansetron group (gp) than in ketamine group at all time interval. Out of 40 patients, shivering was maximum & seen in 17 patients (42.50%) in saline gp, 4 patients (10%) in ondansetron gp and in only 1patient (2.5%) in ketamine gp. Odd ratio of ketamine, ondansetron and saline are 1, 4.33 and 28.33 respectively which means that shivering in saline gp was 28.83 times higher than ketamine gp and 6.65 times higher than in ondansetron .Shivering rate was 4.33 times higher in ondansetron gp than in ketamine gp. Hypotension was lowest in ketamine gp (10%) in comparison to ondansetron gp (22.5%) and saline gp. (20%). Mild sedation was seen in almost all (95%) patients in ketamine gp,

CONCLUSION

Prophylactic low dose ketamine (0.25mg kg(-1)) and Ondansetron (4mg) significantly decreased shivering in patients undergoing spinal anaesthesia without significant side effects.

Origin and characterisation of microparticles in an ice core from the Central Dronning Maud Land, East Antarctica

The scanning electron microscopy-energy dispersive spectroscopic (SEM-EDS) study of selected samples from an ice core collected from Central Dronning Maud Land (CDML), East Antarctica, revealed several microparticles. They are mainly siliceous and carbonaceous particles and have distinct variations in their shape and composition. The morphology and major element chemistry of the particles suggest their origin from either volcanic eruptions or continental dust. The EDS analysis revealed that the volcanic particles are enriched in silica (average SiO2 62%), compared to the continental dust particle (average SiO2 56%). We found that the tephra relating to Agung (1963) and Karkatau (1883) volcanic eruptions, as recorded, in the ice core harbored microbial cells (both coocoid and rods). The occurrence of organic and inorganic particles which bear relation to volcanic eruption and continental dust implies significant environmental changes in the recent past.

Accuracy of DCE – MRI in predicting response in patients treated with taxane based neoadjuvant chemotherapy

Abstract #5120

Background: Neoadjuvant chemotherapy for locally advanced breast cancer is an established treatment option. Several studies have shown DCE-MRI scanning to be the most accurate investigation to assess response to EC chemotherapy. Recent trials have shown that addition of Taxanes increases the overall response rate and the rate of breast conserving surgery. Taxanes act by inhibiting angiogenesis in the tumour and this could potentially affect the quality of the post treatment scan images as DCE-MR scan and cause inappropriate decisions regarding the required surgery.
 Aim: To compare the accuracy of DCE-MR scan in identifying residual disease in patients treated with FEC (Fluoro uracil, Epirubicin, Cyclophosphamide) vs EC (Epirubicin, Cyclophosphamide) followed by Taxane.
 Methods: Patients treated with primary chemotherapy who subsequently underwent breast conserving surgery were identified from a prospectively maintained database. Clinical details including chemotherapy regimes, pre and post chemotherapy MRI data, number of surgical procedures and histological parameters of the excised specimen were obtained.
 Results: A total of 121 patients treated with primary chemotherapy were identified. Of these, 76 were treated with FEC or EC based chemotherapy and 45 were treated with EC+Taxane. DCE-MRI was significantly less accurate (p<0.05) when predicting the size of residual disease in the Taxane group.
 
 Conclusion: DCE MR scan is not as accurate for quantifying size of residual disease in patients treated with taxane when compared with patients treated with traditional FEC/EC based primary chemotherapy. This should be considered when planning surgery after neoadjuvant therapy.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5120.

Incidence trends for human papillomavirus-related (HPV-R) and unrelated (HPV-U) head and neck squamous cell carcinomas (HNSCC) in the United States (US)

6001

Background: HNSCC are etiologically heterogeneous, with one subset primarily attributable to HPV and another to tobacco and alcohol. Methods: Data from SEER9 program registries were used to investigate the potential influence of HPV on incidence and survival of HNSCC in the US from 1973–2003. HNSCCs (N=58,158) were classified by anatomic site as potentially HPV-R (base of tongue; tonsil; oropharynx; N=16,712) or HPV-U (lip; tongue; gum; floor of mouth; palate; other mouth; hypopharynx; ill-defined sites of lip, oral cavity, and pharynx; N=41,446). Joinpoint regression was used to assess incidence trends and life-table methods were used to compare survival for HPV-R and HPV-U HNSCCs. Results: For HPV-R HNSCCs, age-adjusted incidence increased significantly from 1973–2003 (annual percent change [APC] = 0.65), particularly among males (APC=1.02), whites (APC=0.89), and younger ages (APCs for 30–39 = 1.46; 40- 49=1.92; 50–59=0.61, and =60= -0.66). By contrast, HPV-U HNSCC incidence was stable from 1973–1983 and then decreased significantly from 1983–2003 (APC= -2.42). Mean age at diagnosis was younger for HPV-R HNSCC than HPV-U (61.1 vs. 64.5 years; p<0.001), and from 1973- 2003, decreased significantly for HPV-R, but increased for HPV-U. Improvements in overall survival (OS) were observed for HPV-R (all stages) and HPV-U (regional and distant) HNSCC treated by radiotherapy (RT) from 1973–2003, but were more marked for HPV-R HNSCC, e.g. absolute increase in two-year OS for regional disease of 24.4% (vs. 5.8% for HPV-U). OS for HPV-R (local and regional) was significantly better than HPV-U HNSCC if treated by RT, but worse if not so treated. Conclusions: The proportion of HNSCC that is potentially HPV- R increased in the US from 1973–2003, particularly among recent birth cohorts, perhaps due to changing sexual and smoking behaviors. Recent improvements in locoregional control with RT-based therapy may be due in part to a gradual shift in the etiology of the underlying disease.

No significant financial relationships to disclose.

Complications related to positioning in posterior fossa craniectomy

To compare complications associated with surgical position, a retrospective study was conducted on 260 patients who underwent posterior fossa craniectomy. Data collected from the records included demographic profile, American Society of Anesthesiologists' physical status score, neurological status, cranial nerve involvement, associated medical illnesses, anaesthetic technique, patient position, haemodynamic changes, duration of surgery, venous air embolism (VAE), blood loss/transfusion, postoperative complications, duration of ICU stay, and postoperative neurological status. Statistical analysis was done using the Chi-square test and independent t-tests. The demographic profile and preoperative associated medical illnesses of patients were comparable between groups. The incidence of end-tidal carbon dioxide (EtCO2) detected VAE was more (p=0.00) in the sitting position than the horizontal positions (15.2% vs. 1.4%). Blood loss/transfusion and the duration of surgery were significantly higher in the horizontal position (p<0.05). Brainstem handling was the most common cause of prolonged postoperative mechanical ventilation and was seen more in the sitting position. Lower cranial nerve functions were preserved better in the sitting position (p<0.05). Most postoperative complications (surgical or otherwise) were comparable between the groups (p>0.05). Most patients in both groups developed mild-to-moderate disability with independent lifestyle at the seventh postoperative day. To conclude, both sitting and horizontal positions can be used safely in posterior fossa surgeries.

Recurrence rates after DCE-MRI image guided planning for breast-conserving surgery following neoadjuvant chemotherapy for locally advanced breast cancer patients

BACKGROUND

Neoadjuvant therapy results in a significant increase in breast-conserving surgery. However, traditional imaging methods are unable to accurately predict the extent of viable residual disease leading to uncertainty in surgical planning and some previous studies have shown a disproportionately high incidence of locoregional recurrence. Dynamic contrast enhanced-MRI (DCE-MRI) has been shown to provide a potentially more accurate prediction of residual disease.

RESULTS

Patients undergoing neoadjuvant chemotherapy for breast cancer in our unit are staged with the DCE-MRI of the breast performed at 1.5 T before, during and after treatment and the final result was used to plan surgery. Two hundred and four patients with breast cancer were treated with neoadjuvant chemotherapy between 1996 and April 2005. Eighteen of these patients had distant metastases at the time of initial diagnosis and so were excluded from the present study. Following neoadjuvant chemotherapy, 186 patients underwent surgical treatment. Of these, 68 patients had breast-conserving surgery. At a median follow up of 30 months (range: 5.6-72 months) 21 patients in this group developed subsequent recurrence (21/68 - 30%) of whom 9 (9/68 - 13%) had locoregional recurrence, 7 had local recurrence (7/68 - 10%), and 17 (17/68 - 25%) had distant recurrence. Logistic regression analysis revealed only vascular invasion (p=0.006) of the tumour to be significantly associated with overall recurrence. None of the pathological factors (ER, PR status, vascular invasion, lymph node metastases, pathological complete response to neoadjuvant chemotherapy) showed a significant association with locoregional recurrence.

CONCLUSION

Breast-conserving surgery with DCE-MRI planning after neoadjuvant chemotherapy provides an acceptable level of local recurrence without the need for mastectomy.

Screening for HIV infection by health professionals in India

BACKGROUND

Stigma and discrimination, particularly in access to healthcare, remains a major problem for people Infected with HIV in most parts of India.

METHODS

We did a multicentre study (n = 10) with a cross-sectional survey design using a standardized, interviewer-administered questionnaire.

RESULTS

A total of 2200 healthcare providers participated. The knowledge, attitude and practice (KAP) related to HIV service delivery were very poor with a mean overall KAP score of only 49.7% (CI: 49.1-50.3). Only 5%, 5% and 1% of the participants scored more than 75% separately for the dimensions of knowledge, attitude and practice, respectively. Only 24.4% and 36.7% of responders knew that HIV screening was not recommended prior to surgery and pre-employment check-up. Many doctors (19.4%) had refused treatment to people living with HIV/AIDS (PLHA) at least some of the time and nearly half (47.2%) identified and labelled them; 23.9% isolated them in separate care areas and 13.3% postponed or changed treatment based on the patient's HIV status. Screening for HIV prior to elective surgery was done by 67% of providers. While 64.7% of responders were aware of the existence of national guidelines on and recommendations for HIV testing, only 38.4% had read the policy document.

CONCLUSION

There is a growing need to provide care, support and treatment to a large number of PLHA. The capacity of healthcare providers must be urgently built up so as to improve their knowledge of and attitude to HIV to enable them to deliver evidence-based and compassionate care to PLHA in various healthcare settings.

Protein influence on the plasma membrane dielectric properties: in vivo study utilizing dielectric spectroscopy and fluorescence microscopy

We have investigated the origin of the dielectric response of the plasma membrane of living yeast cells (Saccharomyces cerevisiae) by using radiofrequency dielectric spectroscopy. The cells were genetically engineered to overexpress in the membrane of yeast cells a G protein-coupled receptor--the Sterile2-alpha factor receptor protein (Ste2p)--fused to the green fluorescent protein (GFP). Presence of the Ste2-GFP proteins in the plasma membrane was confirmed by exciting the cells at 476 nm and observing with a confocal microscope the emission characteristic of the GFP from individual cells. The dielectric behavior of cells suspended in KCl solution was analyzed over the frequency range 40 Hz-110 MHz and compared to the behavior of control cells that lacked the ability to express Ste2p. A two-shell electrical cell model was used to fit the data starting from known structural parameters and adjustable electrical phase parameters. The best-fit value for the relative permittivity of the plasma membrane showed no significant difference between cells expressing Ste2p (1.63+/-0.11) and the control cells (1.75+/-0.16). This result confirmed earlier predictions that the dielectric properties of the plasma membrane in the radiofrequency range mostly reflect the properties of the hydrophobic layer of the membrane, which is populated by the hydrocarbon tails of the phospholipids and hydrophobic segments of integral membrane proteins. We discuss ways by which dielectric spectroscopy can be improved to be used for tag-free detection of proteins on the membrane.

Molecular Simulations of the Pressure, Temperature, and Chemical Potential Dependencies of Clay Swelling

A new method for the determination of clay swelling thermodynamics from computer simulation is discussed and evaluated. This method allows for the determination of temperature, pressure, and water chemical potential dependence of clay swelling from simulations at a single thermodynamic state point. The temperature dependence and pressure dependence of clay swelling are shown to be directly related to the composite system entropy and volume change, respectively, that accompany swelling. Expressions for the chemical potential dependence of clay swelling are used to determine constant pressure layer spacing and adsorption isotherms, quantities that are well suited for comparison with experimental measurements. This method is evaluated through grand isoshear ensemble simulations of Na-montmorillonite, a prototypical swelling clay. Approximations associated with all expressions are discussed with explicit calculations used to demonstrate their regimes of validity.

Lidocaine infiltration of the scalp does not completely abolish increased intraocular pressure due to skull pin insertion

Insertion of skull pins results in haemodynamic perturbations, which can be blunted by local anaesthetic infiltration of the pin sites. No study has assessed the effects on intraocular pressure. General anaesthesia was induced in 71 patients undergoing cervical spine surgery with attachment of Gardner Wells tongs to the skull. Skull pins were attached five minutes after induction following either saline (group I, 35 patients) or lidocaine (group II, 36 patients) infiltration of scalp. Intraocular pressure, mean arterial pressure and heart rate were recorded before (baseline), immediately after, and 60 s following pin insertion and analysed statistically. Insertion of pins increased intraocular pressure in both groups (from 8.4+/-2.7 to 14.2+/-3.0 mmHg in group I, and from 8.8+/-2.3 to 12.7+/-2.7 mmHg in group II, P < 0.001), which persisted even at 60 s but the increase was significantly greater in group I. Insertion of pins significantly increased blood pressure in group I only. We conclude that lidocaine infiltration at the skull pin sites for Gardner Wells tong attachment fails to completely abolish increased intraocular pressure.

Neoadjuvant chemotherapy in breast cancer: early response prediction with quantitative MR imaging and spectroscopy

A prospective study was undertaken in women undergoing neoadjuvant chemotherapy for locally advanced breast cancer in order to determine the ability of quantitative magnetic resonance imaging (MRI) and proton spectroscopy (MRS) to predict ultimate tumour response (percentage decrease in volume) or to detect early response. Magnetic resonance imaging and MRS were carried out before treatment and after the second of six treatment cycles. Pharmacokinetic parameters were derived from T₁-weighted dynamic contrast-enhanced MRI, water apparent diffusion coefficient (ADC) was measured, and tissue water : fat peak area ratios and water T₂ were measured using unsuppressed one-dimensional proton spectroscopic imaging (30 and 135 ms echo times). Pharmacokinetic parameters and ADC did not detect early response; however, early changes in water : fat ratios and water T₂ (after cycle two) demonstrated substantial prognostic efficacy. Larger decreases in water T₂ accurately predicted final volume response in 69% of cases (11/16) while maintaining 100% specificity and positive predictive value. Small/absent decreases in water : fat ratios accurately predicted final volume non-response in 50% of cases (3/6) while maintaining 100% sensitivity and negative predictive value. This level of accuracy might permit clinical application where early, accurate prediction of non-response would permit an early change to second-line treatment, thus sparing patients unnecessary toxicity, psychological morbidity and delay of initiation of effective treatment.