High-frequency intracellular infection and erythrogenic toxin A expression undergo phase variation in M1 group A streptococci.

A clonal variant of serotype M1 group A streptococcus, strain 90-131, disseminated to several continents, where it was associated with severe systemic infections and toxic shock. Although this strain harbours the speA gene and is efficiently internalized by human epithelial cells, clinical isolates often fail to express the erythrogenic toxin under laboratory growth conditions. Cultures of strain 90-131 were observed to phase vary between small, dry, compact and larger, more mucoid colonies. The former were shown to be poorly internalized by epithelial cells. Analysis of RNA by Northern hybridization demonstrated that the emml, hasA and speA genes were weakly transcribed in cultures derived from the small colonies and highly transcribed in those derived from the large colonies. An insertion mutation in mga (the multigene activator) downregulated the invasion of epithelial cells and the transcription of emm1 and hasA, but had little impact on the transcription of speA. These are the first data to suggest the existence of a common regulatory circuit linking intracellular invasion, M protein, hyaluronic acid capsule and erythrogenic toxin expression by group A streptococcus. Moreover, the genetic instability of toxin expression exhibited by this serotype may impact on laboratory studies that attempt to associate toxin production with toxic shock.

Computerized Clinical Simulation Testing. A new look for the NCLEX-RN examination?

Computerized Clinical Simulation Testing (CST) is under research and development by the National Council of State Boards of Nursing for potential use as a component of the National Council Licensure Examination for Registered Nurses. It is designed to evaluate the application of the clinical decision-making process to the management of client care. The authors describe how CST works, the case development and scoring key development processes, and the plans for the CST pilot study scheduled for spring 1998.

The development of automated client responses for computerized clinical simulation testing.

Computerized Clinical simulation Testing (CST) is under research and development by the National Council of State Boards of Nursing for potential use as a component of the National Council Licensure Examination for Registered Nurses. This interactive software permits the realistic assessment and management of client needs through free-text entry of requests for nursing activities. Implementation of each nursing activity elicits a realistic client response. A major component of the system is a default client response database that incorporates responses for 38 different client condition categories as well as rules for their automation. This article describes and illustrates the characteristics and complexity of this database that is designed to assist in the portrayal of realistic client situations.

Building a nursing activity database for processing free-text entry during computerized clinical simulation testing.

Computerized Clinical Simulation Testing is under research and development by the National Council of State Boards of Nursing for potential use as a component of the National Council Licensure Examination for Registered Nurses. This interactive software permits the realistic assessment and management of client needs through free-text entry of requests for nursing activities, each of which elicit a response from the client. The efficiency and accuracy of system recognition of the free-text requests depends on the careful structuring of a comprehensive nursing activity database. This article describes and illustrates the processes and challenges encountered in building a system-compatible nursing activity database from a very unstructured, unstandardized nursing language.

[Skin neoplasms of the face--diagnosis and possibilities of surgical treatment]. / Rak skóry twarzy--rozpoznanie i mozliwosci leczenia chirurgicznego.

Experiences are presented based on the observation and treatment by surgical methods of 360 patients with facial cutaneous carcinoma in a period of 16 years. The group comprised 57% men and 43% women. Over half the patients had the lesions situated on the nose. In the remaining cases the tumour developed on the cheek (19%), temple (11%), eyelids (6%), forehead (5%) and skin of the lips (3%). Particular therapeutic difficulties were encountered in cases of lesions situated in the medial angle of the palpebral fissure. In 3 cases extensive craniofacial resection with orbitectomy was done for advanced malignant lesions. In 71% of cases basal cell carcinoma was the cause, and in 29% spinocellular carcinoma was diagnosed. Metastases to regional lymph nodes removed during the operation were demonstrated in 16 cases, exclusively caused by spinocellular carcinoma. The problem of surgical safety margin and the main problems of reconstructive procedures in surgical treatment of facial cutaneous carcinoma are discussed.

Diffraction efficiency gain, blazing, and apodizing of a symmetric square reflection grating in an étalon.

First-order diffraction efficiency of 50% into a single beam was obtained from a weak symmetric square metal diffraction grating operated in an étalon at the 632.8-nm He-Ne laser wavelength. Without the étalon the diffraction efficiency was just 2.7% in each of the two first-order beams. First-order diffraction efficiency gain as well as blazing and apodizing of the grating occur because of the resonant paraxial angular spectrum of the étalon.

Cerebral blood flow (CBF) autoregulation in spontaneously hypertensive rats (SHR) during chronic administration of a theophylline derivative (P-23).

Chronic hypertension causes the lower and upper limits of CBF autoregulation to reset to higher blood pressure levels. In the present study we examined whether the theophylline derivative P-23, which had lowered blood pressure in SHR, would influence CBF autoregulation. P-23 (10 mg/kg po) was administered once daily for 4 weeks and tail systolic pressure was measured weekly in this P-23 group and in a control group of SHR. At the end of the treatment period, CBF autoregulation was studied. CBF was determined using the intracarotid 133Xe injection method in halothane/nitrous oxide anesthetised animals. The lower and upper limits of autoregulation were studied in two subgroups of rats by, either raising blood pressure (MAP) stepwise with norepinephrine or lowering MAP stepwise by controlled bleeding and measuring CBF at MAP intervals of 10 mmHg. In the P-23-treated group, blood pressure fell significantly but in the control group, blood pressure increased slightly. The lower part of the autoregulation curve was shifted towards lower pressure in the treated group and the lower limit of autoregulation was significantly different from that in the control. The upper limit of autoregulation was above 180 mmHg in both groups. The beneficial effect of P-23 on CBF autoregulation should be taken into consideration during chronic administration in clinical studies in man.

The role of sympathetic nervous system in the action of dopamine and dobutamine on the function of circulatory system.

To assess the role of peripheral structures of the sympathetic nervous system in the effects of dopamine and dobutamine on some functions of the cardiovascular system, experiments were carried out on anesthetized rabbits in which the blood flow in calf muscles was measured, during rest and during evoked twitches, using the method of 133Xe clearance. The arterial blood pressure and ECG were simultaneously recorded. A complete reversal of the action of dopamine on the arterial blood pressure and heart rate, after sympathetic nerve endings blockade, indicates an important role for the undisturbed neurotransmission in revealing hypotensive properties of this amine. In the action of dobutamine on blood pressure, heart rate and muscle blood flow, the blockade of peripheral structures of the sympathetic nervous system is of minor importance.

The effect of dopamine on blood flow in skeletal muscles.

To explain some mechanisms of the peripheral action of dopamine experiments were carried out on anesthetized rabbits in which the blood flow in calf muscles was measured during rest and during evoked twitches, using the method of 133Xe clearance of Lassen et al.; the arterial blood pressure and ECG were simultaneously recorded. Dopamine reduced the blood flow, particularly after a muscular effort. That effect of dopamine was not blocked by the alpha- and beta-adrenoceptor antagonists phentolamine and propranolol, the dopamine receptor antagonist haloperidol, or by the agent blocking sympathetic nerve endings compound BW392C60. Only low doses of dopamine given after propranolol pretreatment caused an increase in the blood flow. Dopamine depressed the arterial blood pressure, particularly the diastolic one. Pretreatment with phentolamine and haloperidol did not antagonize that effect, while pretreatment with propranolol or BW392C60 abolished or reversed the action of dopamine. The depression by dopamine of the blood flow in an important area of skeletal muscles indicates that part of the circulating blood may be shifted to other vascular beds, e.g. to the viscero - renal one.

Dose-related effects of dopamine on microcirculatory blood flow in resting and active state.

We compared the effects of low and high doses of dopamine and dobutamine (a synthetic catecholamine) on blood flow in relaxed or exercising muscles. Experiments were performed on rabbits. Blood flow in the muscles (calf) was estimated with the clearance method of radionuclide 133Xe. Dopamine and dobutamine were infused (iv) in doses of 20 or 40 micrograms/kg/min. Dopamine reduced muscle blood flow in resting state; this effect was more pronounced after higher doses. Dobutamine increased the flow; low doses were less effective. Dopamine may be an important determinant of the distribution of cardiac output to various vascular regions.

Alterable grating fiber-optic switch.

This paper describes a solid state high speed fiber-optic switch based on dynamically alterable magnetic stripe domains that occur naturally in epitaxial films of rare-earth iron garnet. The array of stripe domains acts collectively as a Faraday effect phase diffraction grating that deflects visible and infrared radiation. Electrically derived magnetic fields in the plane of the film steer incident light from an input fiber to one of several output fibers. Reciprocity and wavelength sensitivity can be exploited for systems applications. Both theoretical and experimental results are presented.