Neuroimmunomodulation: Neuroendocrine Regulation of Immunity: The Effects of Noradrenaline inXenopus Laevis, the South African Clawed Toad

A functional association between the peripheral nervous and the immune system in Xenopus laevis, the South African clawed toad, is demonstrated. This association involves the neurotransmitter noradrenaline (NA), produced and released by the sympathetic nerves of the spleen. Chemical sympathectomy prior to immunization reduces splenic NA, and decreases thymus-dependent (TD), but increases thymus-independent (TI), antibody responses. Immune challenge with representatives of the three antigen classes affects splenic NA levels differentially. Thus, the modulatory effect of NA on immunity will depend on the immunogen used. Carrier-priming of helper function in TD responses stimulates a transitory NA release in the spleen, while subsequent immunization activates a more prolonged release. The two types of challenge differ in the antigenic dose given. The effects of NA also depend on the time when it is applied. If used early in the in vivo TD response, antibody production is increased, but if given later, suppressor function is stimulated, thus decreasing antibody production. NA increases both amplifying and suppressing T cell functions in TD responses through stimulation of the alpha 2 adrenoceptor. Alpha 2 adrenoceptor stimulation decreases, and beta adrenoceptor stimulation increases, anti-TNP reactivity. Since an alpha 2 receptor agonist does not affect lectin-stimulated T cell mitogenesis, while a beta receptor agonist depresses it, NA appears to up-regulate T cell functions by affecting their maturation, rather than their clonal expansion.

The cerebellum and eye-blink conditioning: learning versus network performance hypotheses

Classical conditioning of the eye-blink reflex in the rabbit is a form of motor learning that is uniquely dependent on the cerebellum. The cerebellar learning hypothesis proposes that plasticity subserving eye-blink conditioning occurs in the cerebellum. The major evidence for this hypothesis originated from studies based on a telecommunications network metaphor of eye-blink circuits. These experiments inactivated parts of cerebellum-related networks during the acquisition and expression of classically conditioned eye blinks in order to determine sites at which the plasticity occurred. However, recent evidence revealed that these manipulations could be explained by a network performance hypothesis which attributes learning deficits to a non-specific tonic dysfunction of eye-blink networks. Since eye-blink conditioning is mediated by a spontaneously active, recurrent neuronal network with strong tonic interactions, differentiating between the cerebellar learning hypothesis and the network performance hypothesis represents a major experimental challenge. A possible solution to this problem is offered by several promising new approaches that minimize the effects of experimental interventions on spontaneous neuronal activity. Results from these studies indicate that plastic changes underlying eye-blink conditioning are distributed across several cerebellar and extra-cerebellar regions. Specific input interactions that induce these plastic changes as well as their cellular mechanisms remain unresolved.

Epidemiology of mastitis in pasture-grazed peripartum dairy heifers and its effects on productivity

An observational field study was conducted on 708 heifers in 30 spring-calving dairy herds in the Waikato region of New Zealand. The aim of the study was to describe patterns and effects of intramammary infection (IMI) and clinical mastitis (CM) in the peripartum period. Mammary secretion samples for bacteriological testing were taken from all quarters approximately 3 wk before the planned start of the calving period and within 5 d following calving, in addition to quarters diagnosed with CM within 14 d of calving. Precalving IMI was diagnosed in 18.5% of quarters, and of these, coagulase-negative staphylococci were the predominant isolate (13.5% of quarters). Streptococcus uberis prevalence increased 4-fold to 10.0% of quarters on the day of calving compared with the precalving period. Prevalence of all pathogens decreased rapidly following calving. Clinical mastitis cases were predominantly associated with Strep. uberis (64%). The daily hazard of diagnosis was higher in heifers than in cows (0.06 vs. 0.02/d on d 1 postcalving, respectively), but was not different by d 5 (0.005 vs. 0.002, respectively) of lactation. Intramammary infection with a major pathogen was associated with an increased risk of removal from the herd (15 vs. 10% for infected and noninfected heifers, respectively) and somatic cell count >200,000 cells/mL at subsequent herd tests (15 vs. 8%), but neither CM nor IMI were associated with reduced milk yield or milk solids production. Results suggest that bacterial species involved and the pattern of IMI prevalence in pasture-grazed peripartum heifers differ from those in other production systems. Further, mastitis control programs need to target major environmental pathogens causing precalving IMI, because new infections are likely before the onset of lactation, whereas existing detection and control measures are generally implemented after calving. Novel control programs that reduce new infections due to Strep. uberis immediately before calving are required to reduce the incidence of CM in pasture-grazed dairy heifers.

Risk Factors for Peripartum Mastitis in Pasture-Grazed Dairy Heifers

A longitudinal observational field study was conducted using 708 heifers in 30 spring-calving dairy herds in the Waikato region of New Zealand. The aim of the study was to investigate risk factors for subclinical and clinical mastitis (CM) in the peripartum period using path analysis methods and to find the factors most important at the population level as a basis for potential control programs. Body condition and udder hygiene scores, blood samples, and quarter mammary secretion samples for bacteriology were collected approximately 3 wk before the planned start of the seasonal calving period and again within 5 d following calving. Additionally, milk samples were collected from quarters diagnosed with CM within 14 d of calving. Significant risk factors for subclinical mastitis postcalving were precalving subclinical mastitis (3.32 incidence risk ratio; IRR), low minimum teat height above the ground (1.32 IRR), and unhygienic udder postcalving (1.32 IRR). Significant risk factors for clinical mastitis postcalving were precalving subclinical mastitis (2.14 IRR), Friesian breed (1.94 IRR), low minimum teat height above the ground (2.05 IRR), udder edema (1.81 IRR), and low postcalving nonesterified fatty acid serum concentration (1.55 IRR). Control of precalving subclinical mastitis and udder edema by producers, and enhancement of breed immunity by geneticists were important factors at a population level, and hence, are likely the most rewarding areas to target in any heifer mastitis management program.

Shear wave speed recovery using moving interference patterns obtained in sonoelastography experiments

Two new experiments were created to characterize the elasticity of soft tissue using sonoelastography. In both experiments the spectral variance image displayed on a GE LOGIC 700 ultrasound machine shows a moving interference pattern that travels at a very small fraction of the shear wave speed. The goal of this paper is to devise and test algorithms to calculate the speed of the moving interference pattern using the arrival times of these same patterns. A geometric optics expansion is used to obtain Eikonal equations relating the moving interference pattern arrival times to the moving interference pattern speed and then to the shear wave speed. A cross-correlation procedure is employed to find the arrival times; and an inverse Eikonal solver called the level curve method computes the speed of the interference pattern. The algorithm is tested on data from a phantom experiment performed at the University of Rochester Center for Biomedical Ultrasound.

Tumor Detection in vivo with Optical Spectroscopy

Ultrasound induced blood stasis has been observed for a long time, but to date most experimental observations have been in vitro. In this paper we discuss a possible diagnostic use for this previously undesirable effect of ultrasound - tumor detection in vivo. We demonstrate that, using optical spectroscopy, effects of ultrasound can be used to differentiate tumor from non-tumor in murine tissue. Finally, we propose a novel diagnostic algorithm that quantitatively differentiates tumor from non-tumor with maximum specificity 0.83, maximum sensitivity 0.79, and area under ROC curve 0.90.

In vivo Optical Spectroscopy of Acoustically Induced Blood Stasis

Ultrasound-induced blood stasis has been observed for more than thirty years. Most of the literature has been focused on the health risks associated with this phenomenon and methods employed to prevent stasis from occurring during ultrasound imaging. To date, experimental observations have been either in vitro or invasive. The current work demonstrates ultrasound- induced blood stasis in murine tumor and nontumor tissue, observed through noninvasive measurements of optical spectroscopy, and discusses possible diagnostic uses for this previously undesirable effect of ultrasound.

Vacuum-assisted closure (VAC) therapy in the management of wound infection following renal transplantation

OBJECTIVES

Wound infection in the setting of immunosuppressed state such as renal transplantation (RT) causes significant morbidity from sepsis, prolongs hospital stay and is expensive. Vacuum-assisted closure (VAC) therapy is a new technique of management of wound based on the principle of application of controlled negative pressure. The aim of this study was to assess the efficacy of VAC therapy in the management of wound infection following RT.

MATERIALS AND METHODS

This is a prospective study of a cohort of 180 consecutive RTs performed over a period of 4 years, where the data were retrieved from a prospectively maintained computerised database and case-notes.

RESULTS

9 of 180 (5%) patients developed wound infection following RT which led to cavitations and dehiscence with copious discharge, and refused to heal with conventional treatment. All 9 cases were treated with VAC therapy. The VAC system was removed after a median of 9 (range 3-30) days when discharge from the wound ceased. Four patients were discharged home with portable VAC device and managed on an outpatient basis, where the system was removed after a median 5.5 (range 3-7) days. The median hospital stay after initiation of VAC therapy was significantly shorter (5, range 2-12 days) than on conventional treatment prior to VAC therapy (11, range, 5-20 days) (p=0.003). Complete healing was achieved in all cases.

CONCLUSIONS

The use of VAC therapy is an effective and safe adjunct to conventional and established treatment modalities for the management of wound infection and dehiscence following RT. Key words: Renal transplantation, wound infection, vacuum-assisted closure therapy.

Effects of age on feeding behavior and chemosensory processing in the pond snail, Lymnaea stagnalis

This study used behavioral and electrophysiological techniques to examine age-related changes in the feeding behavior and chemosensory processing in the pond snail, Lymnaea stagnalis. Increasing age was associated with a 50% decrease in long-term food consumption. Analysis of short-term sucrose-evoked feeding bouts showed an age-related increase in the number of animals that failed to respond to the stimulus. Of the animals that did respond increasing age was associated with a decrease in the number of sucrose-evoked bites and a increase in the duration of the swallow phase. These changes were observed with both 0.01 and 0.05M sucrose stimuli but were not seen when 0.1M sucrose was used as the stimulus. Electrophysiological analysis of the chemosensory pathway in semi-intact lip-CNS preparations failed to demonstrate a significant change in the neuronal information entering the cerebral ganglia from the lips via the median lip nerve, but did demonstrate an age-related deficit in the neuronal output from the cerebral ganglia. This deficit was also dependent on the sucrose concentration and mirrored the concentration-dependent changes in feeding behavior. In summary, aging appeared to affect central but not peripheral processing of chemosensory information and suggests that this deficit contributes to the age-related changes in feeding behavior.

Utility of N terminal pro brain natriuretic peptide in elderly patients

OBJECTIVE

To evaluate the utility of N terminal pro brain natriuretic peptide (NT-proBNP) as a diagnostic marker for diastolic dysfunction or failure, systolic dysfunction, and significant valve disorders in patients over 75 years.

DESIGN

Cohort study.

SETTING

Outpatient echocardiography service in a district general hospital.

PARTICIPANTS

100 consecutive patients.

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive predictive values, negative predictive values, and area under receiver operating characteristic curve for NT-proBNP assay in the diagnosis of left ventricular diastolic dysfunction or failure, systolic dysfunction, and significant valve disorders.

RESULTS

For diagnosis of systolic dysfunction NT-proBNP level of 424 pg/ml had a sensitivity of 96%, specificity of 45%, positive predictive value of 36%, and negative predictive value of 96%. The area under the curve was 0.71 (95% confidence intervals: 0.69 to 0.89). In valve heart disease, level of 227 pg/ml had sensitivity of 91%, specificity of 43%, positive predictive value of 40%, and negative predictive value of 92%. Patients with diastolic dysfunction/failure had lower plasma concentrations.

CONCLUSIONS

This study showed that NT-proBNP had excellent negative predictive value for systolic dysfunction and significant valve disorders in very elderly patients. It increased significantly in systolic dysfunction, valve heart disease, and atrial fibrillation. NT-proBNP is not useful in the diagnosis of diastolic dysfunction or diastolic heart failure using standard echocardiography criteria.

In vivo cancer diagnosis with optical spectroscopy and acoustically induced blood stasis using a murine MCa35 model

Ultrasound-induced blood stasis has been observed for more than 30 years. Most of the literature has been focused on the health risks associated with this phenomenon and methods employed to prevent stasis from occurring during ultrasound imaging. To date, experimental observations have been either in vitro or invasive. The current work demonstrates ultrasound-induced blood stasis in murine normal leg muscle versus tumor-bearing legs, observed through noninvasive measurements of optical spectroscopy, and discusses possible diagnostic uses for this previously undesirable effect of ultrasound. We demonstrate that, using optical spectroscopy, effects of ultrasound can be used to differentiate tumor from normal leg muscle tissue in mice. Finally, we propose a novel diagnostic algorithm that quantitatively differentiates tumor from nontumor with maximum specificity 0.83, maximum sensitivity 0.79, and area under receiver-operating-characteristics curve 0.90.

Wavelength-dependent collagen fragmentation during mid-IR laser ablation

Mid-infrared free-electron lasers have proven adept in surgical applications. When tuned to wavelengths between 6 and 7 microm, such lasers remove defined volumes of soft tissue with very little collateral damage. Previous attempts to explain the wavelength-dependence of collateral damage have invoked a wavelength-dependent loss of protein structural integrity. However, the molecular nature of this structural failure has been heretofore ill-defined. In this report, we evaluate several candidates for the relevant transition by analyzing the nonvolatile debris ejected during ablation. Porcine corneas were ablated with a free-electron laser tuned to 2.77 or 6.45 microm-wavelengths with matched absorption coefficients for hydrated corneas that respectively target either tissue water or protein. The debris ejected during these ablations was characterized via gel electrophoresis, as well as Fourier transform infrared spectroscopy, micro-Raman and 13C-NMR spectroscopy. We find that high-fluence (240 J/cm2) ablation at 6.45 microm, but not at 2.77 microm, leads to protein fragmentation accompanied by the accumulation of nitrile and alkyne species. The candidate transition most consistent with these observations is scission of the collagen protein backbone at N-alkylamide bonds. Identifying this transition is a key step toward understanding the observed wavelength-dependence of collateral damage in mid-infrared laser ablation.

Glucose Production in the Human Placenta

Glucose transfer from mother to fetus by placental facilitated diffusion is the dominant mechanism by which the fetus acquires glucose. In small for gestational age pregnancies, fetal glucose concentrations tend to be lower than normal and this persists following delivery. GLUT1 is the major glucose transporter in human placenta but there is no evidence of GLUT1 deficiency as a cause of the lower fetal glucose concentration in small for gestational age pregnancy. The physiological and pathological roles of the other glucose transporters (and there are 14 currently described) are unknown. In recent years, the possibility has been raised that the placenta is itself capable of supplying glucose for fetal needs. This hypothesis derived from glucose isotope studies in normal pregnancy, where dilution of glucose isotope was demonstrated in blood samples taken from the fetal circulation during intravenous infusion of glucose isotope in the mother. Although other gluconeogenic enzymes were known to be present, the placenta was previously considered incapable of glucose secretion because it lacked functional glucose-6-phosphatase. Recent studies, however, have suggested that specific glucose-6-phosphatase may be present in placenta but it may be the product of a different gene from conventional hepatic glucose-6-phosphatase. The presence of the specific transporters necessary for glucose-6-phosphatase activity is currently being investigated. The role of placental glucose secretion in normal and growth-restricted pregnancies is an area of current study.

Sleeping in? The impact of age and depressive sub-type on hypersomnia

BACKGROUND

While early morning wakening is held to be a classic feature of melancholia, we investigate the clinical observation that young patients with melancholia and bipolar depression tend to be more likely to report hypersomnia.

METHODS

We examine age-related rates of those two sleep disturbance patterns in a consecutive set of out-patients with differing depressive sub-types assessed over a 20-year period.

RESULTS

Hypersomnia was more likely to be reported than early morning wakening across all age bands by those with non-melancholic depression. Hypersomnia was also more likely than early morning wakening in younger patients with melancholia and bipolar disorder but, with age, early morning wakening became the dominant pattern.

LIMITATIONS

The study was retrospective, undertaken in a sample attending a tertiary referral unit and artefactual determinants of the associations were not pursued.

CONCLUSIONS

We speculate that hypersomnia may be a non-specific homeostatic coping response to stress and thus to the non-melancholic depressive disorders, but that this pattern is overruled by an early morning wakening pattern in the more biological depressive sub-types as the individual ages, perhaps reflecting a noradrenergic contribution.

Changes in the properties of the modulatory cerebral giant cells contribute to aging in the feeding system of Lymnaea

This study examined whether electrophysiological changes in the endogenous properties and connectivity of the modulatory serotonergic cerebral giant cells (CGCs) contributed to the age-related changes in feeding behavior of the pond snail, Lymnaea. With increasing age there was a decrease in spontaneous CGC firing rates and decreased excitability of the CGCs to both chemosensory stimulation (0.05M sucrose applied to the lips) and direct intracellular current injection. These changes could be accounted for by a decrease in the input resistance of the neuron and an increase in the amplitude and the duration of the after-hyperpolarization. Decreases were also seen in the % of CGC pairs that were electrically coupled causing asynchronous firing. Together these changes would tend to reduce the ability of the CGCs to gate and control the frequency of the feeding behavior. Part of the ability of the CGCs to gate and frequency control the feeding network is to provide a background level of excitation to the feeding motor neurons. Recordings from B1 and B4 motor neurons showed an age-related hyperpolarization of the resting membrane potential consistent with a deficit in CGC function. Increases were seen in the strength of the evoked CGC-->B1 connection, however, this increase failed to compensate for the deficits in CGC excitability. In summary, age-related changes in the properties of the CGCs were consistent with them contributing to the age-related changes in feeding behavior seen in Lymnaea.

Morphological, immunocytochemical and flow cytometric in vitro characterisation of a surface-adherent medulloblastoma

Well-characterised cell lines derived from paediatric intrinsic brain tumours are rare. The different repertoire of cell adhesion molecules expressed by primitive neuro-ectodermal tumours, when compared with gliomas, results in a general lack of propensity for surface adherence. In this study, a highly cellular, medulloblastoma biopsy with a Ki-67 index of 20%, obtained by posterior fossa craniotomy of a two-year-old boy, was maintained in surface- adherent culture for twelve sequential in vitro passages. The culture (VC312R) was characterised by immunocytochemistry and flow cytometry using antibodies against cluster of differentiation 44 (CD44), glialfibrillary acidic protein (GFAP), intermediate filament proteins (Nestin and Vimentin), neural cell adhesion molecules (NCAMs) (ERIC and UJ13A), ganglioside (GD3) and neuron-glial 2 (NG2). GD3, GFAP, ERIC-1, UJ13A and NG2 were detected by neither immunocytochemistry nor flow cytometry. It is of particular interest that we have previously reported that the progenitor cell-associated NG2 heparan sulphate proteoglycan was not expressed in a series of medulloblastoma biopsy sections in our laboratories, while NG2 positivity was seen in supratentorial primitive neuro-ectodermal tumours (PNETs). Strong CD44 positivity was detected on most cells (mean = 93.5% of cells on flow cytometry). In one previous case of medulloblastoma, maintained in our laboratories (IPNN-8) as a substrate-adherent culture, no CD44 staining was detected. Twenty-five percent of cells were strongly Vimentin-positive while 54.5% of cells showed Nestin positivity. The expression of Nestin, Vimentin and CD44 is consistent with primitive neural cell evolution. Non-expression of NCAMs may be consistent with the lack of cell-cell adhesion in this culture, which results in surface adherence. The high expression of CD44 may also indicate a distinct phenotype within primitive neuroectodermal tumours, which determines cell-cell and cell-extra cellular matrix adhesive properties.