We need a balanced debate on direct access.

As active members of a group of like-minded dental care professionals campaigning for the establishment of direct access (DA) for dental hygienists (DHs) we read the BDJ editorial Direct line lack of assurance with interest. However, our interest soon waned and turned to disappointment as it became clear this was to be no balanced debate of the issue.

The long range voice coil atomic force microscope.

Most current atomic force microscopes (AFMs) use piezoelectric ceramics for scan actuation. Piezoelectric ceramics provide precision motion with fast response to applied voltage potential. A drawback to piezoelectric ceramics is their inherently limited ranges. For many samples this is a nonissue, as imaging the nanoscale details is the goal. However, a key advantage of AFM over other microscopy techniques is its ability to image biological samples in aqueous buffer. Many biological specimens have topography for which the range of piezoactuated stages is limiting, a notable example of which is bone. In this article, we present the use of voice coils in scan actuation for an actuation range in the Z-axis an order of magnitude larger than any AFM commercially available today. The increased scan size will allow for imaging an important new variety of samples, including bone fractures.

SU-E-T-522: Analysis of SCERMA-to-KERMA Ratio for Megavoltage Photons.

PURPOSE: To examine the relationship between the primary SCERMA, Sp, and the primary collision KERMA, Kcp, as a function of depth for clinically relevant energy spectra, and to accurately model the SCERMA to KERMA ratio (SKR) for clinical photon beams. METHOD AND MATERIALS: Sp, Kcp, Sp / Kcp (=SKR) for the energy spectra of Cobalt-60 (Co-60), and Mohan 4 MV, 6 MV, 10 MV, 15 MV, and 24 MV photons are analytically calculated over depths from 0 to 40 centimeters in water. The Sp and Kcp are fitted to exponential functions, Sp0exp(-µ'd(l-η'd)) and Kp0exp(-µd(l-ηd)), respectively, with depth d, linear attenuation coefficient µ and beam hardening coefficient η; µ' and η' are the corresponding quantities for Sp. The relationships between µ', η', and SKR vs. µ are examined. Trends between the fitting parameters and µ were also determined, and the results applied to model the SKR of 6× and 15× clinical beams as functions of only µ, η, and depth. RESULTS: SKR decreases with depth for all spectra. We found µ' = (0.80496 + 4.8748µ)µ + 0.005736 and η' = (-0.13076 + 2.6571µ)µ + 0.0036151 for 0.0273/cm<=µ<0.0392/cm, and µ' = 0.87718µ + 0.010864 and η' =(-0.009 - 0.50122µ)µ + 0.0037 for 0.0392/cm <= µ <= 0.0667/cm. This model predicts the normalized SKR/(SKR(d=0)) with a relative deviation of 0.1% and max deviation of 1%. SKR/(SKR(d=0)) from clinical beams 6× and 15× is examined to be in agreement with analytic computation from spectral data with 1% and 0.5% maximum error, respectively. CONCLUSION: Knowledge of normalized SKR is a necessary to calculate scatter dose accurately. We have developed an empirical model to calculate the normalized SKR to be used for clinical (scatter) dose calculation and consequently improve dose calculation accuracy.

Localisation of cannabinoid receptor 1 in rat dorsal root ganglion using in situ hybridisation and immunohistochemistry.

In this study we used in situ hybridisation and double-labelling immunohistochemistry to characterise cannabinoid receptor 1 (CB(1)) expression in rat lumbar dorsal root ganglion (DRG) neurons.Approximately 25% of DRG neurons expressed CB(1) mRNA and displayed immunoreactivity for CB(1). Sixty-nine percent to 82% of CB(1)-expressing cells were also immunoreactive for neurofilament 200, indicative of myelinated A-fibre neurons, which tend to be large- and medium-sized DRG neurons (>600 microm(2)). Approximately 10% of CB1-expressing cells also expressed transient receptor potential vanilloid family ion channel 2 (TRPV2), the noxious heat-transducing channel found in medium to large lightly myelinated Adelta-fibre DRG neurons. Seventeen percent to 26% of CB(1)-expressing cells co-stained using Isolectin B4, 9-10% for calcitonin gene-related peptide and 11-20% for transient receptor potential vanilloid family ion channel 1 (TRPV1), predominantly markers of small non-myelinated C-fibre DRG neurons (<600 microm(2)). These findings suggest that whilst a wide range of DRG neuron phenotypes express CB(1), it is predominantly associated with myelinated fibres.

The synthetic cannabinoid WIN55,212-2 attenuates hyperalgesia and allodynia in a rat model of neuropathic pain.

The analgesic properties of the synthetic cannabinoid WIN55,212-2 were investigated in a model of neuropathic pain. In male Wistar rats, bilateral hind limb withdrawal thresholds to cold, mechanical and noxious thermal stimuli were measured. Following this, unilateral L5 spinal nerve ligation was performed. Seven days later, sensory thresholds were reassessed and the development of allodynia to cold and mechanical stimuli and hyperalgesia to a noxious thermal stimulus confirmed. The effect of WIN55,212-2 (0.1 - 5.0 mg kg(-1), i.p.) on the signs of neuropathy was then determined; there was a dose related reversal of all three signs of painful neuropathy at doses which did not generally alter sensory thresholds in the contralateral unligated limb. This effect was prevented by co-administration of the CB(1) receptor antagonist SR141716a, but not by co-administration of the CB(2) receptor antagonist SR144528, suggesting this action of WIN55,212-2 is mediated via the CB(1) receptor. Administration of SR141716a alone had no affect on the observed allodynia and hyperalgesia, which does not support the concept of an endogenous analgesic tone. These data indicate that cannabinoids may have therapeutic potential in neuropathic pain, and that this effect is mediated through the CB(1) receptor.

Boundary conditions on the partitioning of deaminatively generated benzyl cations.

Nitrogenous entity-separated ion pairs (NESIPs) containing benzyl cations, nitrogen gas, and pivalate anions were generated via thermal deamination of N-benzyl-N-nitrosopivalamide. Some decompositions were performed in methanolic solutions saturated with selected nucleophiles: acetate, azide, or cyanide ions. Trace amounts of benzyl cyanide and tolunitriles were observed; no corresponding products were detected in the acetate and azide cases. Other decompositions were performed in the absence of traditional solvent but in the presence of the nucleophilic salts; again only poor cyanide interception of the cation was observed. The poor showing of the nucleophilic ions, when present, is discussed in the context of the lifetime of the cation, effective nucleophilicity, and cage effects in deamination.

A web-accessible digital atlas of the distribution of nitric oxide synthase in the mouse brain.

We have produced a digital atlas of the distribution of nitric oxide synthase (NOS) in the mouse brain as a reference source for our studies on the roles of nitric oxide in brain development and plasticity. NOS was labeled using nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry. In addition, choline acetyltransferase (ChAT) immunocytochemistry was used to identify cholinergic cells because many of the NADPHd positive cells were thought to colocalize acetylcholine. Some sections were also labeled with antibodies to either the neuronal (nNOS) or endothelial (eNOS) isoforms of NOS. Series of sections from 11 C57/BL6 mice were collected and labeled for NADPHd and/or ChAT. We collected two types of data from this material: color digital photographs illustrating the density of cell and fiber labeling, and computer/microscope plots of the locations of all the labeled cells in selected sections. The data can be viewed as either a series of single-section maps produced by combining the plots with the digital images, or as 3-D views derived from the cell plots. The atlas of labeled cell maps, together with selected color photographs and 3-D views, is available for viewing via the World Wide Web (http:@nadph.anatomy.lsumc.edu). Examination of the atlas data has revealed several points about the distribution of NOS throughout the mouse brain. Firstly, different populations of NADPHd-positive neurons can be distinguished by different patterns of staining. In some brain areas neurons are intensely stained by the NADPHd technique where label fills the cell bodies and much of the dendritic trees. In other brain regions labeling is much lighter, is principally confined to the cytoplasm of the cell soma, and extends only a short distance within proximal dendrites. Intense labeling is typical of neurons in the caudate/putamen and mesopontine tegmental nuclei. Most of the labeled neurons in the cortex also stain this way. Lighter, "granular" label is found in many other nuclei, including the medial septum, hippocampus, and cerebellum. In addition to staining pattern, we have also noted that different subpopulations of NOS-neurons can be distinguished on the basis of colocalization with ChAT. Substantial overlap of the distributions of these two substances was observed although very little colocalization was found in most cholinergic cell groups except the mesopontine tegmental nuclei. Other points of interest arising from this project include the apparent lack of NADPHd labeling in the CA1 pyramidal cells of the hippocampus or the Purkinje neurons in the cerebellum. This observation is especially relevant given that synaptic plasticity in these regions is reported to be nitric-oxide dependent.

Detection of increased tissue concentrations of nerve growth factor with an improved extraction procedure.

Nerve growth factor (NGF) is a protein essential for the survival and normal function of sympathetic neurons. Two-site immunoassays have been developed over the past decade in several laboratories and used to estimate its endogenous concentrations in a variety of effector tissues. However, levels appear restricted to a narrow range, display only a poor correlation with innervation density, and show obvious inter- and intralaboratory variations, the origins of which are unclear. This led us to examine alternative extraction procedures for NGF before quantification. In particular, we have found treatment of tissue extracts with high and low pH in the presence of detergent results in the detection of higher NGF concentrations in immunoassays using either polyclonal or commercially available monoclonal antibodies. These increases were tissue-specific (sciatic nerve, mesenteric arteries, and thoracic aorta > heart and brain > sympathetic ganglia > abdominal aorta) and as much as 10 times greater than the amounts detected by traditional procedures. The method should also prove useful for the assay of other members of the neurotrophin family when appropriate antibodies become available.

Determination of monensin in high-moisture cattle rations by liquid chromatography with postcolumn derivatization.

An existing liquid chromatographic method using postcolumn derivatization has been used extensively to quantitate monensin in animal feeds. Because of the relatively high moisture content of many cattle feed rations, some modifications were made to this method. Several sample-processing steps were evaluated to determine optimum sample-processing procedure. The sample weight/sample diluent ratio was modified, and method linearity was validated for the lower monensin concentrations anticipated in high-moisture cattle rations. The accuracy and precision of data generated at these lower concentrations were also determined. Because of the high moisture content of these rations, data analysis for this method required correction of feed potency for loss on drying. With these modifications, monensin can be accurately determined in high-moisture cattle rations.

Denervation, but not decentralization, reduces nerve growth factor content of the mesenteric artery.

In the present study we applied an improved nerve growth factor (NGF) extraction method to examine the effects of denervation and sympathetic decentralization on NGF levels in vascular tissue. Adult male Wistar Kyoto rats underwent mesenteric arterial denervation or splanchnic nerve transection. Four days after operation, animals were killed, and the mesenteric artery and coeliac-superior mesenteric ganglia were removed. The arterial adventitia was stripped from the media to measure NGF levels in nerve and smooth muscle separately. A high concentration of NGF was detected in the normal artery, 90% of which was in the adventitial layer. Surgical denervation significantly reduced the NGF levels in the artery and ganglia by 78 and 71%, respectively. However, within the artery the level of NGF was reduced in the adventitia but not in the media. Thus, the large reduction of NGF content resulted from the loss of nerve plexus from the artery. In contrast, decentralization did not alter the NGF content in the artery, in either the adventitia or media. Our results are in marked contrast to previous studies reporting elevated levels of NGF following denervation. This discrepancy is explained by the ability of our new procedure to extract much greater amounts of NGF from the tissue.

A public-academic partnership to train psychiatric residents in a rural mental health program.

Psychiatric residency training programs in rural communities face many well-known obstacles, including lack of structure, professional isolation, and excessive demands on residents to provide clinical services. The author describes a psychiatric residency training program in rural North Carolina developed through the collaboration between a rural four-county area mental health program, a medical school department of psychiatry, and a state agency. Rather than focusing on the problems of rural practice, the residency program emphasizes clinical and administrative issues common to all practice settings, fosters an atmosphere in which all staff at the training site support the program's educational mission, and encourages residents to identify with professionals who perform successfully in rural settings.

Atypical myocardial infarction and hypertension: an inner city experience.

The clinical features of 304 patients with acute myocardial infarction with and without hypertension were studied retrospectively. This inner city population consisted of 172 (57%) males and 132 (43%) females; 155 (51%) patients were black, 88 (29%) Hispanic, and 61 (20%) white by self-identification. Hypertension (greater than or equal to 160/95 mmHg) was present on admission in 46% (139) of patients. Typical ischaemic chest pain was the most common presenting symptom and occurred with a similar frequency in patients with and without hypertension. However, the group with hypertension consisted of proportionately more females than males, more frequently had previously diagnosed hypertension and congestive heart failure, and more often presented with shortness of breath and pulmonary oedema. The racial distribution, mean ages, prevalence of angina, previous myocardial infarction, diabetes, smoking, family history of cardiovascular disease, type of myocardial infarction, peak creatinine phosphokinase, plasma cholesterol, and mortality rates were similar in both groups. Thus, female sex, history of hypertension, history of congestive heart failure, and pulmonary oedema characterised patients with compared to those without hypertension. These findings suggest that the higher mortality rate observed in hypertensives during follow-up after myocardial infarction may be due, at least in part, to more severe underlying left ventricular dysfunction.

Clinical features of patients with acute myocardial infarction presenting with and without typical chest pain: an inner city experience.

The clinical features of an inner-city population of 304 patients presenting with acute myocardial infarction (MI) with and without typical chest pain, were studied retrospectively. This population consisted of 172 men and 132 women; 155 (51%) were black, 88 (29%) hispanic, and 61 (20%) white, by self-identification. Typical ischemic chest pain was the presenting symptom in 85% (258); 15% (46) presented with nonchest symptoms, most frequently shortness of breath, abdominal pain, and dizziness. But the frequency of such nonchest symptoms was similar in both groups. When patients were grouped by the presence or absence of chest pain, the proportions of those without chest pain were significantly higher for blacks (22.7%) than hispanics (9.1%, P = 0.001) or whites (4.9%, P less than 0.01). Patients without chest pain also had higher admission systolic (P less than 0.01) and diastolic (P less than 0.01) blood pressures and more frequent histories of congestive heart failure (P less than 0.05), and more often presented with pulmonary edema (P = 0.001) than those with chest pain. Both groups were similar in age, sex, history of hypertension, and presence of hypertension on admission, defined as greater than or equal to 160/95 mmHg, prevalence of diabetes, history of smoking, previous MI, type of MI, history of angina, and mortality rates. Patients without chest pain were characterized by black race, history of congestive heart failure, elevated blood pressure and pulmonary edema than those with typical ischemic chest pain. Thus significant delays in the diagnosis and treatment of this important clinical entity may be reduced by alerting clinicians to these features and by educating selected patient groups.

Transport of endogenous nerve growth factor in the proximal stump of sectioned nerves.

Immunohistochemistry has been used to demonstrate the presence of nerve growth factor (NGF)-like immunoreactivity in normal and sectioned mouse sciatic nerves. In normal nerves, immunoreactive material was not visible unless a silk ligature had previously been applied to constrict the nerves, and only then in the segment of nerve immediately distal to the ligation. Immunoreactivity was visible as early as 2 h after application of the ligature. When nerves were sectioned prior to ligation to prevent the transport of material from nerve terminals within innervated tissues, the NGF-like immunoreactivity continued to accumulate. This accumulation also occurred when a portion of the proximal stump from sectioned nerves was removed from the animal and placed in culture. Quantitative estimate of NGF concentrations with a sensitive immunoassay showed that the amount of NGF present within a segment of the proximal stump of sectioned nerves more than doubled in a 24 h period. The findings indicate that NGF is produced by cells within sectioned nerves, and further suggest that in the normal intact nerve at least a proportion of the NGF being transported derives from these cells.

A de novo 3p;8p unbalanced translocation resulting in partial dup(3p) and partial del(8p).

We present the first case of a de novo translocation resulting in dup(3p). Giemsa banding studies tentatively identified the source of the extra genetic material as 3p. Clinical findings were compatible with those previously reported in dup(3p) patients, further defining this cytogenetic anomaly as a distinct, clinically identifiable syndrome.