Microelectrode measurements of the effects of basolateral adenosine in polarized human intestinal epithelial cells in culture

 Activation of the basolateral receptor for adenosine in HT-29cl.19A cells, by 100 μM adenosine, increased the equivalent short-circuit current (ΔI _sc= 24±2 μA/cm²), depolarized the intracellular potential (ΔV _a= 26±2 mV) and decreased the fractional apical membrane resistance (ΔfR _a=–0.48). The changes in all parameters reached their peak values simultaneously. This suggests that the primary action of the adenosine-activated pathway is on only one membrane. Bumetanide inhibited the transepithelial response and repolarized the cell potential. After preincubation with 100 μM forskolin, application of 300 μM adenosine caused a significant further change in V _a, I _sc, the transepithelial potential (V _t) and fR _a. Together with the results from ion-replacement studies, the observations indicate that adenosine activates channels other than the cystic fibrosis transmembrane conductance regulator (CFTR). The rank order of potencies of adenosine and adenosine analogues implies that the receptor is of the A₂ subtype. Preincubation with 4-bromophenacyl bromide (4-BPB) inhibited the effect of an adenosine analogue by 50%, indicating that activation of phospholipase A₂ may be involved in the adenosine-induced response. Received: 5 August 1998 / Received after revision: 12 October 1998 / Accepted: 5 November 1998     

Multiple single units and population responses during inhibitory gating of hippocampal auditory response in freely-moving rats

Paired clicks were presented to awake, freely-moving rats to examine neuronal activity associated with inhibitory gating of responses to repeated auditory stimuli. The rats had bundles of eight microwires implanted into each of four different brain areas: CA3 region of the hippocampus, medial septal nucleus, brainstem reticular nucleus, and the auditory cortex. Single-unit recordings from each wire were made while the local auditory-evoked potential was also recorded. The response to a conditioning stimulus was compared to the response to a test stimulus delivered 500 ms later: the ratio of the test response to the conditioning response provided a measure of inhibitory gating. Auditory-evoked potentials were recorded at all sites. Overall, brainstem reticular nucleus neurons showed the greatest gating of local auditory-evoked potentials, while the auditory cortex showed the least. However, except for the auditory cortex, both gating and non-gating of the evoked response were recorded at various times in all brain regions. Gating of the hippocampal response was significantly correlated with gating in the medial septal nucleus and brainstem reticular nucleus, but not the auditory cortex. Single-unit neuron firing in response to the clicks was most pronounced in the brainstem reticular nucleus and the medial septal nucleus, while relatively few neurons responded in the CA3 region of the hippocampus and the auditory cortex. Taken together, these data support the hypothesis that inhibitory gating of the auditory-evoked response originates in the non-lemniscal pathway and not in cortical areas of the rat brain.     

Preparation and local anaesthetic activity of benzotriazinone and benzoyltriazole derivatives

Two sets of benzotriazinone and benzoyltriazole derivatives were prepared and tested for local anaesthetic activity in comparison with lidocaine. Several of the prepared compounds exhibited a fairly good activity comparable or superior to that of lidocaine. The presence of a benzotriazinone or a benzoyltriazole moiety as an aromatic system was quite profitable for both the intensity and duration of activity. The acute toxicity in mice of the four most potent compounds of the series was also assessed. Compound 1b, which has an anaesthetic activity comparable to that of lidocaine, was also characterized by a more favourable therapeutic index. All compounds were tested in vitro to evaluate their negative chronotropic action in isolated rat right atria.     

视力客观检测方法的研究

目的研究用视觉诱发电位（ｖｉｓｕａｌｅｖｏｋｅｄｐｏｔｅｎｔｉａｌ,ＶＥＰ）作为视力客观检测的可行性。方法对４０只视力不等的患眼和５０只正常眼,分别记录用不同大小方格（８°、４°、２°、１°、３０、１５和６）刺激时的ＶＥＰ波形。结果患眼组和正常组Ｐ１００振幅及潜时在统计学上有显著性差异。视力与能诱发出波形的最小方格间有明显关系：最小方格为６、１５、３０和１°,平均视力分别为１．１３,０．６２,０．１８和０．０７。视力与Ｐ１００振幅呈正相关,与潜时呈负相关。结论用诱发出ＶＥＰ波形的最小方格大小可估计患者的视力范围     

Relaxation kinetics of formoterol and salmeterol in the guinea pig trachea in vitro

The mechanisms producing long duration of action for formoterol and salmeterol are not fully understood. The aim of the current study was to examine how the concentration of long and short acting ₂-adrenoceptor agonists affects their relaxation kinetics in airway smooth muscle. Onset (time to peak relaxation) and offset of action (reassertion of reversible relaxation following repeated -adrenoceptor blockade and washout) were measured in the guinea pig trachea precontracted postjunctionally by carbachol 0.3 M in vitro. At 10–1,000% (C _1O–C _1,000) of the maximally effective concentration (C ₁₀₀: 150 nM formoterol, 10 M salbutamol, 30 M salmeterol), salbutamol had a shorter time to peak relaxation than did salmeterol. Formoterol and salmeterol had a similar time to peak relaxation at C ₁₀, but, in contrast to salmeterol, formoterol's time to peak relaxation became markedly shorter and similar to that of salbutamol as the concentration was increased up to C _1,000. Significant reversible reasserted relaxation was demonstrated for salmeterol alone at C ₁₀. At C ₃₀–C _1,000, however, salmeterol produced irreversible relaxation only, in spite of repeated -adrenoceptor blockade by sotalol 10 M followed by washout. In contrast, formoterol produced an increasing reversible reasserted relaxation at C ₃₀–C _1,000. Salbutamol produced significant, reversible reasserted relaxation at C _1,000 only. In conclusion, the concentration determines the onset and offset of action for formoterol and to a lesser extent for salbutamol, but not for salmeterol. To cause sustained action, a submaximally effective concentration is sufficient for salmeterol, whereas formoterol requires a maximally effective concentration. The rank order of concentration dependence for the relaxation kinetics is not paralleled by the rank order of lipophilicity for formoterol, salbutamol, and salmeterol. Therefore, factors other than lipophilicity may also play a role in determining the relationship between concentration and relaxation kinetics for the investigated ₂-agonists. Offprint requests to: Anders Linden, MD, PhD     

Closing the theory—practice gap: a model of nursing praxis

Summary

• ? Despite the efforts of nursing theorists, educationalists and practitioners, the theory-practice gap continues to defy resolution. This paper argues that only by reconsidering the relation between theory and practice can the gap be closed.
• ? Drawing upon ideas from teaching and other practice-based disciplines, including nursing, the article suggests that the current model of viewing theory as informing and controlling practice should give way to a mutually enhancing model in which theory is derived from practice, and in turn influences future practice.
• ? This coming together of theory and practice is referred to as nursing praxis, and suggests that informal theory should be unique to each individual encounter with each patient.
• ? The clinical nurse is thus not only a practitioner, but a theorist and researcher, who responds to patients not according to some grand, inflexible theory, but by the process of reflection-in-action, drawing upon their expertise and a repertoire of past experiences and encounters.

     

Neuropathological and neurophysiological effects of interstitial white matter autologous and non-autologous protein containing solutions: Further evidence for a glioma derived permeability factor

Summary The feline infusion model of brain edema was used to evaluate the pathophysiological effects of 0.6ml infusions of autologous serum protein (66%), human serum protein (66%), human glioma cyst fluid and a tissue culture medium (TCM) on the structure and function of the forebrain white matter. These infusions increased local white matter water content by between 10.8 and 12.5 ml/100 g brain and were associated with moderate increases in ICP and CSF outflow resistance and a significant decrease in lumped craniospinal compliance. Cortical somatosensory potentials, motor evoked potentials, EEG and local cerebral blood flow (rCBF) at normocapnia were generally unchanged by the various infusions. All infusates except the 66% autologous serum protein infusion impaired rCBF CO₂ reactivity. Histologically all infusates caused marked extracellular edema. The autologous serum protein infusion caused no additional histological changes whereas the glioma cyst infusates caused profound endothelial and astrocytic swelling, focal endothelial necrosis, basement membrane disruption, perivascular microglial reaction and pavementation and perivascular migration of polymor-phonuclear leukocytes. Similar but less marked changes were seen after infusion of human serum protein whilst the TCM produced only minimal changes. The intensity and extent of Evans Blue extravasation into the forebrain white matter was greatest with glioma cyst infusates and with all infusions reflected the extent to microvascular changes.These studies show that products derived from gliomas cause additional damage to the blood-brain-barrier than that caused by non-autologous serum proteins. These results add further support for the existence of glioma derived permeability factors (GDPF), but suggest neither serum proteins nor glioma derived compounds in the white matter interstitium significantly influence local electrophysiological function. Some limitations of the infusion edema model when using non-autologous infusions and difficulties quantitating brain dysfunction are emphasised.Preliminary results had been presented at the symposium on Brain Edema VIII, which took place at Bern, Switzerland, in June 1990 and have been published in: Reulenet al (eds) 1990. Brain Edema VIII, Acta Neurochirurgica (Wien) [Suppl] 51: 71–73     

Human immunodeficiency virus/acquired immunodeficiency syndrome training from a union perspective.

The authors developed a union sponsored 2-day human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) "train the trainer" program for healthcare workers in the San Francisco Bay Area. The program incorporated the "education for action" approach in an effort to respond to the inadequacies in many traditional, institutional trainings. Service Employees International Union (SEIU) and Labor Occupational Health Program (LOHP) conducted the HIV/AIDS "train the trainer" program for approximately 100 healthcare workers in county public hospitals and community health clinics. After completing the program, these workers went back to their healthcare facilities, or community organizations, and led additional classes on HIV/AIDS transmission and prevention for approximately 600 more people. The goal of the program was to empower healthcare workers to: 1) identify the occupational risks associated with exposure to blood and potentially infectious body fluids at the workplace; 2) develop strategies to reduce those risks; 3) discuss their feelings about caring for an HIV/AIDS patient; and, 4) conduct HIV/AIDS workshops at the workplace.     

Human papillomavirus type 16 DMA in an odontogenic keratocyst

DNA was extracted from an odontogenic keratocyst and assayed for the presence of human papilloma virus (HPV) type 16 DNA sequences using high stringency Southern blot hybridization. HPV type 16 homologous DNA sequences were detected at a copy number of 50-100 genome copies per diploid cell. The oral HPV DNA was not identical to the prototype HPV 16 when cleaved with the restriction enzyme Pst-I, since it appeared to lack the Pst-I C fragment (L2/L1 ORFs) and contained "off-sized" high molecular weight fragments suggestive of integration events into the host cell chromosome.