Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Laboratory Procedures”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
PubMed1995

A direct method for fabricating tongue-shielding stent.

During oral cancer radiotherapy, a tongue-shielding radiation stent guides the patient's upper and lower jaws to a repeatable position, attenuates radiation doses, and protects the tongue and structures adjacent to the irradiated field. Conventionally, a tongue-shielding radiation stent is made of heat-cured polymethyl methacrylate resin in which a low-melting Pb-Bi-Sn alloy is embedded as a shielding layer. Its use involves multiple and lengthy clinical and laboratory procedures. An improved polyvinyl siloxane-metal composite shielding system for radioprotection has recently been developed. This two-component, base and catalyst, putty material offers a shielding effect similar to that of the conventional shielding alloys. Its major advantages are that it is simple to use, requires only one clinical appointment, and affords efficient collaboration between dental and medical teams during cancer treatment. This article describes a simplified direct method of fabricating a tongue-shielding stent with the use of a new polyvinylsiloxane-metal composite in conjunction with impression putty material.

Alloys↗
PubMed1995

Repair of posterior base of a maxillary complete denture by use of a cast of stone and resilient material.

A method to repair a fractured complete denture and simultaneously augment deficient borders or correct an inadequate posterior palatal seal is described. Corrections were made intraorally with modeling compound and an elastomeric impression material. A resilient impression material was used to block out the undercuts in the denture, and repair was accomplished with visible light-cured resin or an autopolymerizing repair resin. This technique simplifies the laboratory procedures and thereby permits the return of the denture to the patient at the same visit.

Acrylic Resins↗
PubMed1995

Heat-cured silicone bimaxillary mouthguard.

A laboratory procedure for the construction of a heat-cured, silicone, custom-made bimaxillary mouthguard for contact sports is described. Contours and vertical dimension are easier to control than with the conventional thermoformed product, and there is no danger of injury from contact between the maxillary and mandibular components.

Dental Prosthesis Design↗
PubMed1997

Clinical performance of resin-bonded fixed partial dentures and extracoronal attachments for removable prostheses.

STATEMENT OF PROBLEM: It is important to evaluate the long-term clinical performance of resin-bonded fixed partial dentures and extracoronal attachments for removable prostheses. PURPOSE: A prospective, long-term clinical study was conducted to evaluate the success of resin-bonded fixed partial dentures since 1985 and of resin-bonded extracoronal attachments from 1987. METHODS: Until 1993, a total of 130 resin-bonded fixed partial dentures had been seated in 101 patients, as well as 12 removable partial dentures (RPDs) with 24 extracoronal retainers in 10 patients. The clinical treatment protocol and the laboratory procedures were standardized. By the end of 1993, it was possible to reexamine 98 patients with a total of 127 resin-bonded fixed partial dentures and all 10 patients with removable partial dentures. The average time in function for the resin-bonded fixed partial dentures at the time of examination was 3.4 years and 2.3 years for the removable restorations. RESULTS: During the period of observation, one retainer failed on six of the resin-bonded fixed partial dentures, which represents a failure rate of 4.7%. Debonding of extracoronal attachments was recorded for 8.3% of the total number of retainers. CONCLUSION: The resin-bonded fixed partial denture technique can be considered to be a clinically reliable method of treatment, and permits the expansion of indications beyond a classical three-unit resin-bonded fixed partial denture. Long-term clinical success of removable partial dentures with resin-bonded extracoronal retainers warrants additional clinical studies.

Adolescent↗
PubMed1997

Temporary prosthesis for laryngotracheal stenosis: a clinical report.

Clinical and laboratory procedures to fabricate a transitional prosthesis for patients treated with laryngofissure surgery have been described. Hard resin promoted healing of the surgical area and maintained the opening because of its stiffness. The prosthesis, which can be highly polished, was easily removed by the patient for proper hygiene and was fabricated to accurately fit the inside margins of the wound. All these factors were important for a good clinical result.

Humans↗
PubMed1997

Composite occlusal surfaces for acrylic resin denture teeth.

Acrylic resin denture teeth often exhibit rapid occlusal wear, which may lead to a loss of chewing efficiency and a loss of vertical dimension of occlusion. The use of metal occlusal surfaces on the acrylic resin denture teeth will minimize occlusal wear. Several articles have described methods to construct metal occlusal surfaces; however, these methods are time-consuming, costly, and sometimes considered to be unesthetic. These methods also require that the patient be without the prosthesis for the time necessary to perform the laboratory procedures. This article presents a quick, simple, and relatively inexpensive procedure for construction of composite occlusal surfaces on complete and partial dentures.

Acrylic Resins↗
PubMed1999

Clinical methods for adjusting retention force of cast clasps.

Careless adjusting methods to increase or decrease retention by grinding, polishing, or bending the clasp arm can lead to instability of the removable partial denture, damage to the surrounding tissues, and fracture of the clasp arm. This article describes systematic evaluation criteria and adjusting methods of retention force of a cast clasp. Excessive retention can be reduced by using a proper adjustment method, which depends on the cause. Poor retention can be increased temporarily, but it will decrease again. Evaluations and adjustment of poor retention will contribute to the diagnosis of the cause and will establish clinical and laboratory procedures that will lead to making clasps with proper retention in the future.

Dental Clasps↗
PubMed1999

Hinged mandibular removable complete denture for post-mandibulectomy patients.

The presence of excessive lingual undercuts after mandibulectomy and surgical reconstruction is a rare clinical condition and presents unique prosthodontic challenges. The goals of prosthodontic treatment include: providing lip support, improving articulation, reducing drooling, and regaining favorable esthetics. This article describes the fabrication of a hinged removable mandibular complete denture prosthesis using a sectional impression tray technique and a custom-made hinge mechanism. Clinical and laboratory procedures of the prosthetic treatment are described, and the advantages and disadvantages are reviewed.

Acrylic Resins↗
PubMed1999

Crack propensity of porcelain laminate veneers: A simulated operatory evaluation.

STATEMENT OF PROBLEM: Anterior teeth are especially subject to the thermal variations of ingested food and drinks. Postoperative cracks of porcelain laminates are considered a possible consequence of polymerization shrinkage, function, and thermocycling. PURPOSE: This investigation was conducted to define the parameters associated with the development of cracks in porcelain veneers using cyclic thermal fatigue. MATERIAL AND METHODS: Twenty-seven maxillary incisors were restored with porcelain laminate veneers and subjected to thermocycling (5 degrees C to 50 degrees C) for 1000 cycles. Ceramic cracks were reported for 11 of the 27 specimens. Teeth were sectioned and prepared for SEM analysis. Measurements of the ceramic and the luting composite thicknesses were performed for each specimen at different restoration locations (facial, incisal, and proximal). RESULTS: No significant differences in the ceramic or the luting composite thicknesses were observed between cracked and uncracked specimens. However, significant differences were observed in the ratio of the ceramic and luting composite thicknesses. Most cracked samples exhibited a ratio at the facial location below 3.0 (2.6 +/- 0.35), whereas most noncracked specimens were above this value (3.9 +/- 0.19). Incisal and especially proximal measurements alone were not significantly different between cracked versus uncracked specimens. Ceramic was slightly thinner in the facial aspect than in the proximal aspect, which was also thinner than the incisal aspect. Composite in the facial aspect was thinner in the cervical area than in the incisal third of the tooth. CONCLUSIONS: Significant cyclic temperature changes can induce the development of flaws in porcelain veneers. Control of tooth reduction and the application of die spacers during laboratory procedures undoubtedly represent key elements; a sufficient and even thickness of ceramic combined with a minimal thickness of luting composite will provide the restoration with a favorable configuration with regard to crack propensity, namely, a ceramic and luting composite thickness ratio above 3.

Analysis of Variance↗
PubMed2003

Approach to analysis of single nucleotide polymorphisms by automated constant denaturant capillary electrophoresis.

Melting gel techniques have proven to be amenable and powerful tools in point mutation and single nucleotide polymorphism (SNP) analysis. With the introduction of commercially available capillary electrophoresis instruments, a partly automated platform for denaturant capillary electrophoresis with potential for routine screening of selected target sequences has been established. The aim of this article is to demonstrate the use of automated constant denaturant capillary electrophoresis (ACDCE) in single nucleotide polymorphism analysis of various target sequences. Optimal analysis conditions for different single nucleotide polymorphisms on ACDCE are evaluated with the Poland algorithm. Laboratory procedures include only PCR and electrophoresis. For direct genotyping of individual SNPs, the samples are analyzed with an internal standard and the alleles are identified by co-migration of sample and standard peaks. In conclusion, SNPs suitable for melting gel analysis based on theoretical thermodynamics were separated by ACDCE under appropriate conditions. With this instrumentation (ABI 310 Genetic Analyzer), 48 samples could be analyzed without any intervention. Several institutions have capillary instrumentation in-house, thus making this SNP analysis method accessible to large groups of researchers without any need for instrument modification.

Algorithms↗
PubMed1997

Metastatic malignant mesothelioma presenting as colonic polyps.

A 66-year-old male engineer diagnosed with malignant pleural mesothelioma 4 years previously had thoracotomy, radiotherapy, and chemotherapy. He was followed regularly with chest computed tomography (CT) scan and had been asymptomatic. During one of his physical examinations, routine sigmoidoscopy showed incidental colonic polyps which were biopsied. Subsequently, recurrence of pleural mesothelioma and peritoneal involvement by mesothelioma was documented. Two of the polyps showed metastatic malignant mesothelioma in the lamina propia which strongly resembled adenocarcinoma histologically causing difficulty in making definitive diagnosis. Review of the literature disclosed no previously documented similar occurrence. This case shows the importance of clinical history and ancillary laboratory procedures such as immunohistochemistry and electron microscopy to avoid diagnostic pitfalls.

Adenocarcinoma↗
PubMed2000

Comparing in situ distribution coefficients and exchangeability of radiocaesium in freshwater sediments with laboratory predictions.

Two short-term (24 h) laboratory procedures, based on measurement of the affinity and capacity of the specific binding sites for radiocaesium on illitic clay minerals, are used to predict the in situ 137Cs distribution coefficients (KD) in two Dutch freshwater sediments. Differences in the measured amount of specific binding sites between the sediments are shown to be related to differences in the particle size and illite content. A procedure based on measurement of the combined parameter KD[NH4+] predicts the measured in situ 137Cs distribution in both sediments very well. This is remarkable because the in situ data are based on 137Cs/sediment contact times of > 1 year, while previous experiments have shown that increasing contact times between Cs+ and sediments decreases the short-term exchangeability of caesium, as measured by extraction with a high ammonium concentration. The good predictions of the 37Cs solid/water distribution by short-term ion-exchange experiments, therefore, indicate that more 137Cs in the sediments is exchangeable than is measured by the commonly used extraction with high ammonium concentrations.

Cesium Radioisotopes↗
PubMed2001

Lead and zinc in the Wallsend Burn, an urban catchment in Tyneside, UK.

This paper examines lead and zinc concentrations in topsoils and stream sediments of public access areas in an urban catchment in Tyneside, UK. It examines the extent and severity of metal contamination, explores spatial patterns in relation to urban and industrial development, and makes inferences about potential metal mobility. Total and acetic-acid extractable lead and zinc concentrations, organic content and pH were determined on 121 topsoil and 22 stream sediment samples using standard laboratory procedures. Using the lowest trigger thresholds for total lead and zinc, almost 75% and 91%, respectively, of topsoil samples were classified as contaminated; proportions were rather lower for acetic acid extractable metals. Similarly, approximately 45% and 95% of stream sediment samples were contaminated with lead and zinc, respectively. The spatial distribution of metal concentrations was characterized by a hotspot pattern, with highest values in central and southern parts of the catchment where there is a long urban and industrial history. The potential mobility of zinc is considerably greater than that of lead in both topsoils and stream sediments, and for both metals is slightly higher in the stream sediments than in the topsoils; both of these differences are statistically significant (P < 0.05). The implications of the findings in this paper for assessment and monitoring of metal contaminated areas are explored.

England↗
PubMed2005

Advances in real-time PCR: application to clinical laboratory diagnostics.

The polymerase chain reaction (PCR) has become one of the most important tools in molecular diagnostics, providing exquisite sensitivity and specificity for detection of nucleic acid targets. Real-time monitoring of PCR has simplified and accelerated PCR laboratory procedures and has increased information obtained from specimens including routine quantification and differentiation of amplification products. Clinical diagnostic applications and uses of real-time PCR are growing exponentially, real-time PCR is rapidly replacing traditional PCR, and new diagnostic uses likely will emerge. This review analyzes the scope of present and potential future clinical diagnostic applications of this powerful technique. Critical discussions focus on basic concepts, variations, data analysis, instrument platforms, signal detection formats, sample collection, assay design, and execution of real-time PCR.

Fluorescent Dyes↗
PubMed1998

Decreased activity of striatal monoamine oxidase B after rapid eye movement (REM) sleep deprivation in rats.

The striatum seems to be the main brain region involved in stereotyped behavior induced by dopaminergic agonists. Rapid eye movement (REM) sleep deprivation increases dopaminergic agonist-induced stereotypy and produces biochemical changes in striatal dopaminergic neurotransmission. However, the mechanism underlying the increased dopaminergic sensitivity induced by REM sleep deprivation has not been elucidated. In an attempt to determine some of the biochemical changes in striatal dopaminergic neurotransmission that could contribute to REM sleep deprivation effects, we measured the activity of monoamine oxidase (MAO) A and B, the enzymes responsible for dopamine and beta-phenylethylamine (beta-PEA) deamination in striatum. Male adult rats were deprived of REM sleep for 96 h by the flower-pot technique. MAO A and B were assayed radioisotopically in the mitochondrial fraction by standard laboratory procedures, using [14C]-5-hydroxytryptamine (5-HT) and [14C]-beta-phenylethylamine (beta-PEA), as substrates for MAO A and MAO B, respectively. The results showed no significant statistical differences in striatal MAO A activity, whereas a significant decrease in MAO B activity was observed. The results are discussed in terms of the possible involvement of beta-PEA, a striatal endogenous trace amine, which potentiates dopaminergic neurotransmission and may participate in the increased dopaminergic sensitivity observed after REM sleep deprivation.

Animals↗
PubMed1980

Hydrocortisone suppression test and discriminant analysis in differential diagnosis of hypercalcaemia.

Experience is reported of the hydrocortisone suppression test in 140 hypercalcaemic patients, comprising 98 new cases of hyperparathyroidism and 42 cases of non-parathyroid malignant disease. The diagnostic accuracy of the test was compared in 168 patients with that of discriminant analysis, the discriminant functions being derived from plasma inorganic phosphate, alkaline phosphatase, chloride, bicarbonate, and urea, and the erythrocyte sedimentation rate. The hydrocortisone test and discriminant analysis each achieved a diagnostic accuracy of about 93% in 148 patients with either non-parathyroid malignant disease or hyperparathyroidism without osteitis fibrosa. When both tests pointed to the same diagnosis, they were wrong in less than 1% of cases. The hydrocortisone test was not helpful in patients with osteitis fibrosa. Both tests can be performed in any hospital with reliable standard laboratory services. Used in combination they have a high predictive value in distinguishing hypercalcaemia of parathyroid origin from that due to non-parathyroid malignant disease and have not led to errors of clinical importance. They should continue to play a major role in the differential diagnosis of hypercalcaemia until a prompt and reliable service finally establishes parathyroid hormone assay as the definitive laboratory procedure.

Adult↗
PubMed1989

Problems in genetic prediction for Huntington's disease.

Experience with nearly 300 applicants for predictive testing for Huntington's disease has shown that apart from the expected problems such as those related to third-party interests and the effects of an adverse test result, there were several less foreseen difficulties. These included the finding that some applicants were already clinically affected, requests for testing of minors, unintentional risk alteration for relatives, and the use of research samples for service purposes. More of the problems involved clinical and counselling aspects rather than laboratory procedures.

Adolescent↗