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PubMed1997

Antifungal susceptibility testing: technical advances and potential clinical applications.

The clinical application of in vitro antifungal susceptibility testing has been limited by a lack of reproducibility and uncertain clinical relevance. As a result of several collaborative studies, the National Committee for Clinical Laboratory Standards (NCCLS) has proposed a standardized antifungal susceptibility test method, NCCLS M27-T. More convenient, user-friendly methods (microdilution broth and stable gradient technology) have been evaluated, and the potential for a similar process with a disk diffusion method is apparent. Adaptation of the standard method for susceptibility testing of filamentous fungi appears promising. The existence of a standardized method facilitates meaningful analysis of studies addressing the issue of clinical relevance of antifungal susceptibility testing. Correlation of MICs with clinical response to therapy is beginning to emerge, most notably in relation to fluconazole and itraconazole therapy for oropharyngeal candidiasis associated with infection with the human immunodeficiency virus. This accumulated experience with antifungal susceptibility testing allows us to provide several specific recommendations for antifungal susceptibility testing in the clinical laboratory. Application of this developing technology to new antifungal agents and other disease states will enhance our ability to effectively deal with the emerging problem of fungal infection.

Antifungal Agents↗
PubMed2001

Technical advance: reduction of Fe(III)-chelates by mesophyll leaf disks of sugar beet. Multi-component origin and effects of Fe deficiency.

The characteristics of the Fe(III)-chelate reductase activity have been investigated in mesophyll disks of Fe-sufficient and Fe-deficient sugar beet leaves. The Fe(III)-chelate reductase activity of mesophyll disks was light dependent and increased markedly when the epidermis was removed. Iron(III)-citrate was photo-reduced directly by light in the absence of plant tissue. Total reductase activity was the sum of enzymatic mesophyll reduction, enzymatic reduction carried out by organelles exposed at the disk edge and reduction caused by the release of substances both by exposed mesophyll cells and at the disk edge. Compounds excreted were shown by HPLC to include organic anions, mainly oxalate, citrate and malate. When expressed on a leaf surface basis, Fe deficiency decreased the total mesophyll Fe(III)-chelate reductase activity. However, Fe-sufficient disks reduced less Fe than the Fe-deficient ones when expressed on a chlorophyll basis. The optimal pH values for Fe(III) reduction were always in the range 6.0-6.7. In control leaves Fe(III)-citrate and Fe(III)-malate were the substrates that led to the highest Fe reduction rates. In Fe-deficient leaves Fe(III)-malate led to the highest Fe reduction rates, followed by Fe(III)-EDTA and then Fe(III)-citrate. K:(m) values for the total reductase activity, enzymatic mesophyll reduction and enzymatic reduction carried out by organelles at the disk edge were obtained.

Chenopodiaceae↗
PubMed1990

Rapid admixture blood warming: technical advances.

The technique of rapid admixture blood warming of cold erythrocyte units is designed to warm erythrocyte units rapidly (less than 30 sec) while simultaneously providing saline for dilution. However, questions have been raised about the recommended use of a standard 250-ml bolus of 70 degrees C admixture saline, the uniformity and speed of blood unit warming, the difficulties inherent in keeping saline bags at 70 degrees C, and the safety of the methodology. To answer these questions, a series of tests were performed and modifications of the technique were introduced. The mean weight of 1000 successive units of erythrocytes for adult infusion was 305 g (range 220 to 410). The maximum temperature was 44 degrees C, using an internal temperature probe (1-cm temperature gradations; 2-sec recording intervals) when the smallest unit was admixed with a 250 ml 70 degrees C saline bolus; the largest unit had a minimum temperature of 30 degrees C. Plasma Hgb, osmotic fragility, and K of the minimum size erythrocyte unit showed no significant deviation from its control. Both thermographic photographs and the internal temperature recordings of the erythrocyte units demonstrated that solely due to fluid turbulence, uniform mixing occurs within approximately 30 sec of beginning the admixture process. Inverting the blood units caused a thermal layering of fluids and an unacceptable maximum blood temperature of 50 degrees C. There was no difference between the mixing time or efficacy in the presence of standard or large-bore iv tubing or additional in-line filters. Volumes of the 250-ml saline bags for admixture decreased markedly with deviations in electrolyte composition after greater than 2 wk at 70 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Transfusion↗
PubMed2004

Application of rational practice and technical advances for optimizing radiation dose for chest CT.

Though clinical benefits of CT exceed the adverse effects of radiation, the increasing use of CT has raised a compelling case for reducing radiation exposure. This controversy has been compounded by the sheer magnitude of CT examinations being performed annually, alleged overuse, and inappropriate selection of optimum scanning parameters, all of which expose the patient population to increased radiation exposure. Recommended clinical strategies for radiation dose optimization include optimization of scanning parameters and creating awareness and adopting guidelines for legitimate indications for CT scanning to avoid overuse and hence, the associated over-exposure. Whereas technological advances have increased the applications of the modality, it is also assisting in development of promising techniques to reduce associated radiation exposure, while maintaining "optimum image quality" needed to make a confident diagnosis. The present pictorial essay describes the fundamentals of CT radiation exposure and need for CT radiation dose reduction on the basis of documented scanning practices and technological advances.

Humans↗
PubMed2002

Midface lift of the malar fat pad: technical advances.

Most of the advances of the past decade in face lift technique have been directed to correcting the aging changes of the midface. With many midface lift techniques, patients typically experienced a prolonged period of periorbital ecchymosis and edema. Pessa's description of the anatomy of the malar septum has led to modifications of the senior author's (J.Q.O.) malar fat pad lift technique, designed to minimize postoperative ecchymosis and edema following mobilization of the malar fat pad. Preoperatively, markings of the cutaneous insertion of the malar septum are placed at the infraorbital location. This line approximates the caudal margin of the musculus orbicularis oculi. Dissection under the malar fat pad is performed sharply under direct visualization. Care is taken to stay caudal to the malar septum insertion as marked on the skin. Refinements in the dissection of the midface malar fat pad have not altered the effective repositioning achieved. By leaving the malar septum intact, the amount of postoperative edema and ecchymosis is less than formerly associated with the dissection over the infraorbital orbicularis. With rare exception, patients were able to resume their usual activities and employment after a recovery period of 10 to 21 days postoperatively.

Adipose Tissue↗
PubMed1980

Technical advances in corneal microsurgery.

Barraquer was the first ophthalmic surgeon who consistently took into account modern technology when planning the details of his operating theatre. Since then, ceiling suspension of a microsurgical unit, with remote control for all functions in ophthalmic surgery, has been taken for granted. During the recent decade the microscopes and instruments used have been remarkably improved. This is true for the microscope itself and its accessories, but even more so for many of our remote-controlled instruments, such as rotortrephines for perforating grafts, rotorkeratomes and rotorknives, and recently for the new automatic lamellarkeratom. Better cutting quality leads to more precise wound edges, to better coaptation, and to better optical results. These systems also can be useful in cataract surgery, especially in the implantation of new intraocular lenses.

Cornea↗
PubMed2005

Proteomics meets microbiology: technical advances in the global mapping of protein expression and function.

The availability of complete genome sequences for a large number of pathogenic organisms has opened the door for large-scale proteomic studies to dissect both protein expression/regulation and function. This review highlights key proteomic methods including two-dimensional gel electrophoresis, reference mapping, protein expression profiling and recent advances in gel-free separation techniques that have made a significant impact on the resolution of complex proteomes. In addition, we highlight recent developments in the field of chemical proteomics, a branch of proteomics aimed at functionally profiling a proteome. These techniques include the development of activity-based probes and activity-based protein profiling methods as well as the use of synthetic small molecule libraries to screen for pharmacological tools to perturb basic biological processes. This review will focus on the applications of these technologies to the field of microbiology.

Bacterial Proteins↗
PubMed1992

Technical advances in transjugular intrahepatic portosystemic shunts.

A transjugular intrahepatic portosystemic shunt (TIPS) can be created percutaneously with the Palmaz balloon-expandable stent. This article describes a transjugular-only approach with a 16-gauge needle. A functional and efficacious shunt can be achieved in most cases with stent diameters of 8-10 mm. Occasionally, a 12-mm-diameter shunt is necessary for effective variceal decompression. The procedure is considered successful when the portosystemic gradient is lowered to 12 mm Hg or less after stent placement. Hepatic vein stenosis in the shunt outflow can develop after the TIPs procedure. This complication has been treated successfully with additional stent placement. TIPS can undoubtedly be performed successfully and safely with a transjugular-only approach; however, the full impact of TIPS on the treatment of portal hypertension remains to be determined.

Esophageal and Gastric Varices↗
PubMed2002

Rat laryngeal transplant model: technical advancements and a redefined rejection grading system.

The rat laryngeal transplant model, introduced in 1992, laid the basic science foundation that contributed to the first successful human larynx transplant in 1998. Over 1,500 rat transplants later, numerous modifications have improved the model, increasing the initially reported evaluability rate of 50% to almost 100%. The observed histologic rejection process has been altered, as well. We report the technique modifications, as well as the results of a new study using nonimmunosuppressed, allogenic transplantations, in order to define a new rejection grading system. Using the updated model, we performed 50 transplantations between LBN(f1) donor rats and Lewis recipients. Larynges from 8 groups of 5 to 10 animals were harvested at intervals between 1 and 20 days after transplantation. The larynges were examined grossly and microscopically in a blinded manner for evidence of rejection. A multivariable linear regression model was used to define a new rejection grading scale. All 50 animals survived their assigned posttransplantation period. No animals exhibited vascular thromboses, for an evaluability rate of 100%. Histologic criteria in 7 categories and gross criteria in 5 categories demonstrated increased rejection proportional to the amount of time after transplantation. The equation [Group = -2.209 + 0.465 x (Size) + 0.901 x (VA Flow) + 0.613 x (Muscle) + 1.040 x (Thyroid)] reproducibly grades rejection on the basis of gross and histologic findings. New modifications to the rat laryngeal transplant model have conferred greatly improved animal survival rates and anastomotic patency rates. Additionally, the observed rates of rejection have been reduced in comparison to those of initial studies. This updated rejection staging system will be used to compare immunosuppressive regimens in future rat laryngeal transplant studies.

Animals↗
PubMed1992

Technical advances in intra-oral model systems used to assess cariogenicity: experimental design and analysis (reactor paper).

In situ cariogenicity-testing models must show evidence of compliance with valid clinical parameters, and this has been achieved with respect to pyrophosphate-, monofluorophosphate-, and zinc citrate trihydrate-containing dentifrices, where earlier in vitro studies failed to predict clinical efficacy. Parameters for validity testing should include the use of enamel fluoride uptake, plaque and/or saliva fluoride assessments, re-/demineralization assays of appliance-borne enamel slabs or slices, and plaque microbial, biochemical, and pH studies. Model reliability must be capable of withstanding repeat calibration experiments where the dosage, frequency of application, and/or duration of exposure to a new product may be varied. Furthermore, the number of enamel slabs/slices carried per appliance (and the number of artificial caries lesions per enamel insert) requires to be defined. Such studies should be repeated, but whether in the same or different subjects, or with or without cross-over, has to be determined. However, the capability of reproducing a clinically proven dose-response is essential. Models must be sensitive enough to detect changes in any test product F-concentration, but only equivalence claims should be permitted. Thus, superiority cannot be established, since accuracy may not be assumed beyond the upward limits of a clinically validated range. Finally, models should not be so exclusive in design as to preclude independent verification of their findings.

Dental Caries↗