Multiple modes of action potential initiation and propagation in mitral cell primary dendrite

The mitral cell primary dendrite plays an important role in transmitting distal olfactory nerve input from olfactory glomerulus to the soma-axon initial segment. To understand how dendritic active properties are involved in this transmission, we have combined dual soma and dendritic patch recordings with computational modeling to analyze action-potential initiation and propagation in the primary dendrite. In response to depolarizing current injection or distal olfactory nerve input, fast Na(+) action potentials were recorded along the entire length of the primary dendritic trunk. With weak-to-moderate olfactory nerve input, an action potential was initiated near the soma and then back-propagated into the primary dendrite. As olfactory nerve input increased, the initiation site suddenly shifted to the distal primary dendrite. Multi-compartmental modeling indicated that this abrupt shift of the spike-initiation site reflected an independent thresholding mechanism in the distal dendrite. When strong olfactory nerve excitation was paired with strong inhibition to the mitral cell basal secondary dendrites, a small fast prepotential was recorded at the soma, which indicated that an action potential was initiated in the distal primary dendrite but failed to propagate to the soma. As the inhibition became weaker, a "double-spike" was often observed at the dendritic recording site, corresponding to a single action potential at the soma. Simulation demonstrated that, in the course of forward propagation of the first dendritic spike, the action potential suddenly jumps from the middle of the dendrite to the axonal spike-initiation site, leaving the proximal part of primary dendrite unexcited by this initial dendritic spike. As Na(+) conductances in the proximal dendrite are not activated, they become available to support the back-propagation of the evoked somatic action potential to produce the second dendritic spike. In summary, the balance of spatially distributed excitatory and inhibitory inputs can dynamically switch the mitral cell firing among four different modes: axo-somatic initiation with back-propagation, dendritic initiation either with no forward propagation, forward propagation alone, or forward propagation followed by back-propagation.     

Informed and patient-centered decision-making in the primary care visits of African Americans with depression

Objective

We examined the prevalence and extent of informed decision-making (IDM) and patient-centered decision-making (PCDM) in primary care visits of African Americans with depression.

Comparable fMRI activity with differential behavioural performance on mental rotation and overt verbal fluency tasks in healthy men and women

To explicate the neural correlates of sex differences in visuospatial and verbal fluency tasks, we examined behavioural performance and blood-oxygenation-level-dependent (BOLD) regional brain activity, using functional magnetic resonance imaging, during a three-dimensional (3D) mental rotation task and a compressed sequence overt verbal fluency task in a group of healthy men (n=9) and women (n=10; tested during the low-oestrogen phase of the menstrual cycle). Men outperformed women on the mental rotation task, and women outperformed men on the verbal fluency task. For the mental rotation task, men and women activated areas in the right superior parietal lobe and the bilateral middle occipital gyrus in association with the rotation condition. In addition, men activated the left middle temporal gyrus and the right angular gyrus. For verbal fluency, men activated areas in the bilateral superior frontal gyrus, right cingulate gyrus, left precentral gyrus, left medial frontal gyrus, left inferior frontal gyrus, thalamus, left parahippocampal gyrus and bilateral lingual gyrus, and women activated areas in the bilateral inferior frontal gyrus and left caudate. Despite observing task related activation in the hypothesised areas in men and women, no areas significantly differentiated the two sexes. Our results demonstrate comparable brain activation in men and women in association with mental rotation and verbal fluency function with differential performance, and provide support for sex differences in brain–behaviour relationships.     

A Clinical Trial of a New All-in-One Peripheral-Short Catheter

The objectives of this survey were to: 1) understand current peripheral IV stabilization practices within our hospital and 2) evaluate the use of a new closed IV catheter system with a built-in stabilization platform. All medical-surgical patients within an 851-bed acute care hospital with peripheral-short catheters were evaluated within a 3-day period for catheter securement, dwell time, and signs of complications. Additionally, catheter restart data were collected from a renal telemetry unit for 2 weeks. Catheter and dressing protocols were then standardized to a new catheter system with a built-in stabilization platform (Nexiva? Closed Catheter System) and an absorbent transparent dressing (SorbaView^® 2000). After a 2-week trial of the new protocol, catheters were again evaluated for securement and restart data were again collected from the renal telemetry unit. Staff nurse (N = 42) opinions on the new catheter system and dressing combination were sought, as well as a vote on willingness to change to the new catheter system and dressing. Results demonstrate improvement in catheter stabilization (out to 96 hours of dwell-time), decreased restarts, a high clinical preference for the new catheter/dressing system, and a high willingness to convert to the new system. Results indicate that the new closed IV catheter system with a built-in stabilization platform and the transparent absorbent dressing evaluated in this survey may help to improve catheter securement and increase dwell-time. Research studies utilizing more rigorous randomized, controlled comparisons are warranted.     

Short‐ and long‐term vertical diplopia secondary to blunt trauma

This report describes the short‐ and long‐term ocular signs and symptoms of a patient with an orbital blow‐out fracture and discusses the differential diagnosis of vertical diplopia. A blow‐out fracture occurs when blunt trauma is applied either directly to the eyeball itself or the orbital rim and usually results in a fracture of the orbital floor with consequential excavation and entrapment of orbital contents in the fracture. Vertical diplopia is a common presenting symptom for a blow‐out fracture of the orbit but careful considerations should be given to other potential conditions leading to such diplopia. A patient is presented who suffered a blow‐out fracture almost a decade earlier, secondary to blunt trauma to the globe. The clinical findings are provided immediately after the trauma, post‐surgery and during a recent ocular examination.     

Communication problems of hearing-impaired patients

AIM: The main objective of this national survey was to check the findings of an earlier pilot survey. This had found that patients who had a hearing-impairment and were in hospital were often seriously disadvantaged by their disability. METHOD: The survey was conducted by questionnaire and the sampling frame confined to hearing-impaired patients who had been in hospital during the previous three years. A total of 359 completed and valid questionnaires were returned. RESULTS: The responses confirmed the finding of the pilot survey. They indicated that there were serious shortcomings in the ability of many hospital staff to cope with the problems of hearing-impaired patients. CONCLUSION: Common causes of the problems were identified. The major factor was inadequate training of both nurses and doctors in deaf awareness and the associated communication skills. Other significant factors included patients concealing their disability, pressure of work and poor communication between staff. Appropriate training at all staff levels should eliminate a high proportion of these problems.     

绝经后女性类风湿关节炎患者骨密度变化影响因素分析

目的探讨绝经后女性类风湿关节炎(RA)患者发生骨质疏松(OP)的原因。方法收集63例绝经后女性RA患者一般临床资料、疾病活动相关指标、手足X线资料,并同时测量患者7个部位的骨密度。结果23例患者(36.5%)有至少一处检测部位表现为低骨量。前臂和桡尺骨远端的低骨密度发生率(23.8%)与OP总发生率(28.6%)无显著性差异(P>0.05)。OP的发生与疾病活动指标及糖皮质激素的使用均无相关性。多元回归分析显示绝经的年限和关节腔狭窄为低骨量发生的独立危险因素(P<0.05);而雌激素替代疗法(HRT)为低骨量发生的唯一保护因素(P<0.05),小剂量糖皮质激素对本组患者的骨密度无影响。结论OP是绝经后女性RA患者的常见并发症,绝经年限长和关节破坏严重是低骨量发生的独立危险因素,HRT是防治低骨量的保护因素。     

Long-term survival after chemoradiotherapy for locally advanced squamous cell carcinoma of the esophagus

Seven patients with locally far-advanced, inoperable, squamous cell cancer of the esophagus were given two cycles of concurrent radiation and chemotherapy. Each cycle consisted of 5-fluorouracil 1,000 mg/m2/day given as a continuous intravenous infusion over 96 hours, cisplatin 75 mg/m2 given as an intravenous bolus on day 1, and methotrexate 40 mg/m2 given as an intravenous bolus on days 8 and 15. Three thousand rads of radiation were given in 15 fractions between days 1 and 19. Six patients are evaluable for response. Symptomatic relief was obtained by all six and was complete in 4. Five patients achieved a complete response, and two remain alive and disease free. Five of the six evaluable patients survived for at least 12 months. Aggressive chemoradiotherapy may result in significant survival prolongation and symptomatic palliation in this poor-prognosis subset of patients with esophageal cancer.     

Primary care for HIV-exposed and infected children: translating progress into practice

Recent advances have changed the guidelines for diagnosing and managing pediatric human immunodeficiency virus (HIV) infection. HIV-exposed and HIV-infected children should be evaluated by, or in consultation with, pediatric HIV specialists. Primary care practitioners play a vital role in identification of infants and children at risk for HIV infection and can work collaboratively with pediatric HIV specialists to provide state-of-the-art care. With the use of perinatal zidovudine, perinatal transmission rates have been reduced to 3% to 4%, and they may be reduced even further by the use of combination antiretroviral therapy during pregnancy, viral load monitoring, and obstetric interventions. Diagnosis of HIV infection can be determined in all perinatally infected infants by 6 months of age. Combination antiretroviral therapy is the standard of care for HIV-infected children. It has become increasingly effective, but complex. Families living with HIV are affected by a number of psychosocial issues. Disclosure of HIV diagnosis to a child is an important clinical issue. As HIV-infected children grow older, medical and psychosocial issues may impact school performance. The plan of care to address specific needs of HIV-infected children should be a collaborative effort between the children, their families, the primary care team, and the multidisciplinary pediatric HIV specialty team.     

Breast-Feeding and Its Promotion

An increase in the rate of breast-feeding is beneficial for the developing countries both with regard to economy and health (1). The nutritional and immunological superiority of breastfeeding compared to artificial feeding is universally recognized. Breast-feeding has advantages not only for the infant but also for the mother and the family unit. It has also been recognized as the most effective method of birth-spacing in developing countries (2, 3) and it has advantages for the family because of its convenience and low cost (4).