In vivo laser Doppler holography of the human retina

The eye offers a unique opportunity for the non-invasive exploration of cardiovascular diseases. Optical angiography in the retina requires sensitive measurements, which hinders conventional full-field laser Doppler imaging schemes. To overcome this limitation, we used digital holography to perform laser Doppler perfusion imaging of human retina with near-infrared light. Two imaging channels with a slow and a fast CMOS camera were used simultaneously for real-time narrowband measurements, and offline wideband measurements, respectively. The beat frequency spectrum of optical interferograms recorded with the fast (up to 75 kHz) CMOS camera was analyzed by short-time Fourier transformation. Power Doppler images drawn from the Doppler power spectrum density qualitatively revealed blood flow in retinal vessels over 512 × 512 pixels covering 2.4 × 2.4 mm² on the retina with a temporal resolution down to 1.6 ms. The sensitivity to lateral motion as well as the requirements in terms of sampling frequency are discussed.

Does persisting fear sustain catatonia?

OBJECTIVE

To examine the psychological substrate of catatonia.

METHOD

Reviewing the historical descriptions and explanations of catatonic behaviours by clinicians from its delineation in the 19th century to the present.

RESULTS

Patients with catatonia are often haunted by fears and terrors; this has not been widely appreciated, and certainly was lost from view in the days when catatonia was considered a subtype of schizophrenia. The report contributes to resolving a major question in catatonia: is the mind in stupor inactive, as the blank state that we picture in anesthetized patients, or is the mind active, so preoccupied as to exclude all other influences.

THE MAIN FINDING

Persistent fear occupies the mind of catatonic patients.

CONCLUSION

The signs of catatonia are adaptations to persistent fear, akin to tonic immobilization. The relief afforded by sedation supports this interpretation.

Impact of viral hepatitis aetiology on survival outcomes in hepatocellular carcinoma: A large multicentre cohort study

While HBV and HCV are risk factors for HCC, uncertainty exists as to whether these viral infections have prognostic significance in HCC. Thus, we compared the overall survival of patients with HBV, HCV and nonviral HCC, and evaluated whether the presence of HBV and HCV predicts patient outcomes. We conducted a multicentre study of HCC cases diagnosed at six Melbourne tertiary hospitals between Jan 2000-Dec 2014. Patient demographics, liver disease and tumour characteristics and patient outcomes were obtained from hospital databases, computer records and the Victorian Death Registry. Survival outcomes were compared between HBV, HCV and nonviral hepatitis cases and predictors of survival determined using Cox proportional hazards regression. There were 1436 new HCC cases identified including 776 due to viral hepatitis (HBV 235, HCV 511, HBV-HCV 30) and 660 from nonviral causes. The median survival of HBV, HCV and nonviral HCC patients was 59.1, 28.4 and 20.9 months, respectively (P<.0001). On multivariate analysis, independent risk factors for survival included HCC aetiology, gender, BCLC stage, serum AFP, total number and size of lesions, and serum creatinine and albumin. After adjusting for these and method of detection, HBV remained an independent predictor of improved overall survival when compared to both nonviral (HR 0.60%, 95% CI 0.35-0.98; P=.03) and HCV-related HCC (HR 0.51%, 95% CI 0.30-0.85; P=.01). In this large multicentre study, HBV is independently associated with improved overall survival compared with HCV and nonviral-related HCC. Further studies are needed to determine the underlying factor(s) responsible.

High speed optical holography of retinal blood flow

We performed noninvasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (∼30 microns diameter) over 400×400  pixels with a spatial resolution of ∼8 microns and a temporal resolution of ∼6.5  ms.

Assessing particle kinematics via template matching algorithms

Template matching algorithms represent a viable tool to locate particles in optical images. A crucial factor of the performance of these methods is the choice of the similarity measure. Recently, it was shown in [Gao and Helgeson, Opt. Express 22 (2014)] that the correlation coefficient (CC) leads to good results. Here, we introduce the mutual information (MI) as a nonlinear similarity measure and compare the performance of the MI and the CC for different noise scenarios. It turns out that the mutual information leads to superior results in the case of signal dependent noise. We propose a novel approach to estimate the velocity of particles which is applicable in imaging scenarios where the particles appear elongated due to their movement. By designing a bank of anisotropic templates supposed to fit the elongation of the particles we are able to reliably estimate their velocity and direction of motion out of a single image.

Mathematical modeling and simulation in animal health. Part I: Moving beyond pharmacokinetics

The application of mathematical modeling to problems in animal health has a rich history in the form of pharmacokinetic modeling applied to problems in veterinary medicine. Advances in modeling and simulation beyond pharmacokinetics have the potential to streamline and speed-up drug research and development programs. To foster these goals, a series of manuscripts will be published with the following goals: (i) expand the application of modeling and simulation to issues in veterinary pharmacology; (ii) bridge the gap between the level of modeling and simulation practiced in human and veterinary pharmacology; (iii) explore how modeling and simulation concepts can be used to improve our understanding of common issues not readily addressed in human pharmacology (e.g. breed differences, tissue residue depletion, vast weight ranges among adults within a single species, interspecies differences, small animal species research where data collection is limited to sparse sampling, availability of different sampling matrices); and (iv) describe how quantitative pharmacology approaches could help understanding key pharmacokinetic and pharmacodynamic characteristics of a drug candidate, with the goal of providing explicit, reproducible, and predictive evidence for optimizing drug development plans, enabling critical decision making, and eventually bringing safe and effective medicines to patients. This study introduces these concepts and introduces new approaches to modeling and simulation as well as clearly articulate basic assumptions and good practices. The driving force behind these activities is to create predictive models that are based on solid physiological and pharmacological principles as well as adhering to the limitations that are fundamental to applying mathematical and statistical models to biological systems.

The Region of Difference Four is a Robust Genetic Marker for Subtyping Mycobacterium caprae Isolates and is Linked to Spatial Distribution of Three Subtypes

Alpine Mycobacterium caprae isolates found in cattle and red deer display at least three genetic variations in the region of difference four (RD4) that can be used for further differentiation of the isolates into the subtypes 'Allgäu', 'Karwendel' and 'Lechtal'. Each genomic subtype is thereby characterized by a specific nucleotide deletion pattern in the 12.7-kb RD4 region. Even though M. caprae infections are frequently documented in cattle and red deer, little is known about the transmission routes. Hence, robust markers for M. caprae subtyping are needed to gain insight into the molecular epidemiology. For this reason, a rapid and robust multiplex PCR was developed for the simultaneous detection of three M. caprae RD4 subtypes and was used to subtype a total number of 241 M. caprae isolates from animals (145 cattle, 95 red deer and one fox) from Bavaria and Austria. All three subtypes occur spatially distributed and are found in cattle and in red deer suggesting transmission between the two species. As subtypes are genetically stable in both species it is hypothesized that the described genetic variations developed within the host due to 'within-host replication'. The results of this study recommend the genomic RD4 region as a reliable diagnostic marker for M. caprae subtype differentiation.

What was learned: studies by the consortium for research in ECT (CORE) 1997-2011

OBJECTIVE

To review the findings of the four-hospital collaborative studies of electroconvulsive therapy (ECT) in unipolar depressed patients known as CORE between 1997 and 2011. Unipolar depressed patients were treated with bilateral ECT, and on remission were randomly assigned to a fixed schedule continuation ECT or to combined lithium and nortriptyline for 6 months. A second study compared three electrode placements in unipolar and bipolar depressed patients.

METHOD

Nineteen published reports were reviewed. The findings are compared with those of a parallel multi-hospital study of ECT led by a Columbia University Collaboration (CUC) team that studied right unilateral ECT in a similar population with similar inclusion/exclusion and remission criteria. Successful ECT was followed by placebo, nortriptyline alone, or combined lithium, and nortriptyline.

RESULTS

Relapse rates after remission were similar with fixed schedule ECT as with medications. Predictors of outcome (psychosis, suicide risk, polarity, melancholia, atypical depression, age) and technical aspects (electrode placement, seizure threshold, speed of response) are discussed,

CONCLUSION

The findings offer criteria to optimize the selection of patients, the technique, and outcome of ECT for unipolar and bipolar depressed patients. Continuation ECT is an effective alternative to continuation treatment with lithium and nortriptyline. Bilateral electrode placement is more efficient than alternative placements. ECT relieves both bipolar and unipolar depression.

The seizure, not electricity, is essential in convulsive therapy: the flurothyl experience

BACKGROUND

For more than 50 years, research in convulsive therapy has been focused on the impact of electricity and seizures on memory and not on brain chemistry or neurophysiology. Brief pulse and ultra-brief pulse currents replaced sinusoidal currents. Electrode placements were varied, energy dosing was altered, and electricity was replaced by magnetic currents.

METHOD

The published experiences and archival records of seizures induced by camphor, pentylenetetrazol, and flurothyl are reviewed and compared with the changes induced by electricity.

FINDINGS

The clinical efficacy of chemically induced seizures is equal to that of electrical inductions. Seizure durations are longer, and impairment of cognition and memory is less. Electroconvulsive therapy replaced chemical treatments for ease of use, not for greater efficacy or safety.

CONCLUSIONS

The brain seizure, not the method of induction, is the essential element in the efficacy of convulsive therapy. Seizure induction with chemicals avoids the direct effects of electricity on brain functions with lesser effects on cognition. Reexamination of chemical inductions of seizures as replacements for electricity is encouraged.