Morphological and functional demonstration of rat dura mater mast cell-neuron interactions in vitro and in vivo

The effects of changes in temperature on primary and secondary endings of isolated cat muscle spindles were investigated under ramp-and-hold stretches and different degrees of pre-stretch. Temperature-induced alterations of the discharge frequency were compared over a temperature range of 25–35°C. Both primary and secondary endings responded to warming with increasing discharge frequencies when the spindle was pre-stretched by 5–10% of its in situ length. The following differences between the temperature effects on primary and secondary endings were observed: (1) The temperature coefficients (Q₁₀) obtained from the discharge frequencies during the dynamic and static phase of a stretch were similar for endings of the same type, but they were larger in primary endings (range of Q₁₀: 2.3–3.3; mean: 2.9) than in secondary endings (range of Q₁₀: 1.6–2.2; mean: 2.0); (2) With primary endings, but not with secondary endings, the temperature sensitivity (imp s⁻¹ °C⁻¹) was larger during the dynamic phase than during the static phase of a stretch; (3) In primary endings, the fast and slow adaptive components occurring in the discharge frequency during the static phase of a stretch clearly increased with warming while in secondary endings, the slow decay was less affected, and the fast decay showed no change; (4) In relaxed spindles, the excitatory effect of warming was overlaid by a strong inhibitory effect as soon as the temperature exceeded about 30°C, resulting in an abrupt cessation of the background activity in most secondary endings, but not usually in primary endings. In general, warming induced an enhanced stretch sensitivity in both types of ending, and additionally an inhibitory effect that is obvious only in secondary endings of relaxed spindles. The different effects of temperature on the discharge frequency of primary and secondary afferents are assumed to be caused by different properties of their sensory membranes.     

An analysis of an air-ambulance program for children

Air-ambulance services are extremely expensive to operate and maintain. The value of their existence has been questioned in this era of rationalization and downsizing. We examined the cost, safety, flight crew composition, types of trauma, and effectiveness of our air-ambulance program at the Children's Hospital of Eastern Ontario (CHEO) over a 3-year period, 1994-1997. During this time, 392 children were aeroevacuated to CHEO, 113 surgical (29%), 136 medical (35%), and 143 neonates (36%). Of the surgical cases, 43% were transferred for orthopaedic trauma, the commonest being fractured femur, 23% for general surgical cases, most common being thoracoabdominal trauma, and 22% for neurosurgical reasons, most commonly basilar skull fractures. The average response time (time from which the call was received to the time when the helicopter reached the patient site) for all of the cases was 46 min. The average travel time (time from departure of patient site to arrival at CHEO) for these same cases was 25.59 min. The air-ambulance program for children in the Ottawa-Carleton Eastern Ontario areas, was found to be safe, effective, and allowed earlier specialized medical care to be provided.     

放射状角膜切开手术中微穿孔对角膜内皮的影响

目的：评价放射状角膜切开术（ＲＫ）中微穿孔对术后１年内角膜内皮的影响。方法：应用角膜内皮镜及角膜内皮分析仪研究４８例ＲＫ术中微穿孔和未穿孔眼的角膜内皮形态学变化,分别在术前及术后１、３、６、１２个月行角膜内皮检查及分析。结果：比较手术前后角膜内皮的数量、平均面积、最大面积和最小面积,穿孔眼及未穿孔眼差异无显著性,但内皮细胞面积两组都有扩大的趋势。结论：ＲＫ术后一年内无论微穿孔还是未穿孔眼的角膜内皮     

Nonsurgical management of extradural hematomas in children

With the advent of computerized tomography (CT), an increasing number of patients with only minimal neurological symptoms and no signs of brain herniation are found to harbor subacute or chronic extradural hematomas (EH's). The authors present the cases of 11 symptomatic but neurologically normal children with medium to large EH's managed by close observation. These EH's were discovered 4 hours to 6 days after injury; three were in the posterior fossa, seven over the frontoparietal convexity, and one in the temporal fossa. These clots were followed by serial CT scans. Nine children recovered without surgery from 4 to 18 days after injury, and all had evidence on CT of spontaneous clot resorption. Of these nine EH's, five clots displayed volume expansion from 5 to 16 days after injury before final resorption occurred. Expansion correlated with persistence or increase in symptoms, whereas resorption correlated with improvement. Two patients showed gradual uncal herniation on Days 6 and 8, respectively, presumably during the "expansile phase" of their clots. Both had emergency craniotomy and recovered without morbidity. It is hypothesized that the resorption dynamics of the subacute or chronic EH are similar to that of the chronic subdural hematoma, with predictable volume changes, and the outcome of each lesion depends on the interplay between the patient's intracranial pressure buffering capacity and the rate of volume change. If subtle signs of brain dysfunction are adopted to signal the failure of conservative treatment and the need for craniotomy, these patients may be safely, and many successfully, managed without surgery. Factors that influence outcome of medical treatment include the size, location, configuration, and the rapidity of accumulation of the clot, the presence of associated intradural lesions, the extracranial decompression of blood through skull diastases, and the age of the patient. These factors, the criteria for patient selection, and the indications for immediate operative intervention are discussed.     

Hepatic clearance of drugs. II. Experimental evidence for acceptance of the “well-stirred” model over the “parallel tube” model using lidocaine in the perfused rat liverin situ preparation

Theoretical analysis of two models of hepatic drug clearance revealed that one powerful discriminator between them is the effect of changes of hepatic blood flow on either the emergent drug concentration or the availability of a highly extracted compound when operating under linear conditions. Lidocaine (extraction ratio 0.997) was employed in the discriminatory studies. The behavior of this drug under linear conditions (input lidocaine concentrations < 5 mg/ liter) to changes in hepatic blood flow rate (10–16 ml/min per liver) was examined in the perfused rat liver in situpreparation. The steady-state output lidocaine concentration in the blood leaving the liver was predicted better by a well-stirred model than by a parallel tube model. As anticipated, the clearance of a poorly extracted compound, antipyrine (extraction ratio 0.08),was unaltered by changes in hepatic blood flow. These experimental findings, and the data from the literature, point to the acceptance of the well-stirred model, which describes the liver as a well-stirred compartment with the drug in the hepatic venous blood being in equilibrium with that in the liver.Supported in part by National Institutes of Health Grant GM 16496 and the Patent Fund, Graduate Division, University of California, San Francisco.Abstracted in part from a dissertation submitted by K. Sandy Pang to the Graduate Division, University of California, San Francisco, California, in partial fulfillment of the Doctor of Philosophy degree requirements.     

p27kip1的研究现状及展望

细胞的增殖在许多生理及病理生理学过程中起着极为重要的作用,并受许多细胞内及细胞外因素的调控,细胞的适度增殖取决于细胞内外的正增殖信号与负增殖信号在一定水平上的动态平衡.细胞周期是细胞增殖、分化的最后共同通路,在此对细胞的增殖与分化进行干预、调控的作用可能大于对其上游诸因素的干预.