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PubMed1979

The preservation of surface-associated micro-organisms prepared for scanning electron microscopy.

Scanning electron microscopy (SEM) has become a popular means of studying micro-organisms which associate with surfaces. However, as yet no detailed examination has been made of the influence of specimen preparation on the number of organisms finally seen on the SEM screen. In this investigation critical assessment is made of the influence of a wide range or preparative factors on the preservation of filamentous bacteria associated with the epithelial surfaces of rat intestine. Organisms were quantitated using a rigorous counting method (transect line analysis); statistical testing of these counts enabled the comparison of different preparative factors. The composition of the fixative was found to significantly influence the number of organisms preserved; of the fifteen fixatives studied, Karnovsky's fixative with ruthenium red best preserved surface-associated organisms. The influence of other factors on the number and appearance of preserved organisms was also examined. These factors included the washing of specimens prior to fixation, the storage of fixed specimens, and the handling and storage of critical point dried specimens. The results are discussed with reference to the optimal methods for preparing specimens for SEM.

Animals↗
PubMed1976

Venereal transmission of hepatitis B virus. The possible role of vaginal secretions.

The presence of Type B viral (Australia antigen related serum) hepatitis in vaginal specimens was investigated and compared with that in saliva specimens in a group of patients during the acute phase of their illness. Hepatitis B surface antigen was detectable in most vaginal and salivary secretions during the phase of antigenemia and not in hepatitis B surface antigen-negative controls. Despite care in collection, occult blood was detected in the majority of specimens, but the positivity for hepatitis B surface antigen did not depend on the presence of occult blood. Recovery studies were performed in both vaginal fluids and saliva to determine if inhibitors to hepatitis B surface antigen were similar to those observed in stool samples. Significant inhibition was not observed. Although infectivity of the specimens was not established from this study, handling of these specimens as potentially infective material is recommended.

Female↗
PubMed1993

Histologic preparation for Mohs micrographic surgery. The single section method.

BACKGROUND: Tissue processed by Mohs micrographic surgery is usually cut into several sections before it is processed. OBJECT AND METHODS: We describe a single section method, in which the tissue is not subdivided, for preparing a tissue specimen for histologic examination in Mohs micrographic surgery. RESULTS: This technique saves time for both technicians, who prepare fewer specimens, and physicians, who have fewer histologic specimens to interpret. It may minimize false-positive margins and technical errors. CONCLUSIONS: Small specimens are handled best by this technique; however, the size of the specimen is limited only by the size of the cryostat chuck and histologic slide. The single section method is technically more difficult for preparing specimens that contain cartilage or ones that are extremely concave or convex, such as specimens from the conch of the ear.

Histocytological Preparation Techniques↗
PubMed2025

Global biological sample collections from tuberculosis studies: a scoping review.

Progress in tuberculosis vaccine development is hindered by the incomplete understanding of protective immunity and other disease mechanisms. An interconnected network of sample biorepositories from tuberculosis studies could help to address these gaps. To assess the feasibility of such a resource, we conducted a scoping review of tuberculosis observational studies and vaccine clinical trials. The included studies collected at least one biological sample from tuberculosis cases, contacts, or controls and had more than 100 participants. We contacted the corresponding authors of these studies to determine the sample availability and interest in interconnected biorepositories. For the period 2014-24, we identified 104 observational studies and 18 vaccine trials that collected biological samples from 35 075 tuberculosis cases, 39 450 contacts or controls, and 45 628 trial participants across 43 countries. The commonly collected samples were blood, human genomic DNA, RNA, and sputum. Interest among the contacted investigators was high. Interconnected sample biorepositories could facilitate large-scale investigations and accelerate progress towards tuberculosis vaccine development.

Humans↗
PubMed2001

Influence of laboratory homogenization procedures on trace element content of food samples: an ICP-MS study on soft and durum wheat.

Sample contamination as a consequence of abrasion of grinding tools during the homogenization of food materials to be analysed for trace elements was addressed. The possible release of 15 trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn, V, Zn) from six different grinding and milling devices, operating either continuously or discontinuously, was evaluated. All the devices were commercially available and were representative of models usually employed in food and agricultural laboratories. Wheat grains belonging to one soft and one durum cultivar were used as test material. The determination of the analyte concentrations in subsamples submitted to the different preparation treatments was performed by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). Accordingly, a suitable digestion method was developed and the ArC+ interference affecting Cr determination was evaluated and corrected. Statistical differences with respect to the control were detected for 10 elements (Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb) and in most cases contamination of the samples was traced back to the composition of the grinding equipment. None of the investigated devices was contamination-free with respect to all of the quantified elements. Abrasion of the grinding tools was higher with durum wheat than with soft wheat as a consequence of their different hardiness.

Analysis of Variance↗
PubMed1994

Bacteriological evaluation of groups of beef carcasses before the wash at six Alberta abattoirs.

A method has been developed for the bacteriological evaluation of groups of beef carcasses which can be used to measure the degree of control over hygiene during hide removal and carcass dressing in abattoirs. This method, which enumerates aerobic mesophilic bacteria automatically using a hydrophobic grid membrane filter, was applied at six abattoirs. Two hundred excision samples (5 x 5 x 0.5 cm) were taken at 10 sites on the external surface of a group of 20 carcasses (five carcasses were sampled on each of four consecutive daily visits) for group-carcass evaluation at each abattoir. For each abattoir, the mean log10 Most Probable Number of Growth Units (MPNGU) and between-carcass variance component were obtained for each site and the average over sites. Using the average within-abattoir variance of this study and previously published studies involving 76 additional carcasses (Jericho et al. 1993), it was determined that 20 carcasses are more than adequate to estimate the mean log10 MPNGU per cm2 within 0.5 units at a site. The distribution of the log10 MPNGU per cm2 over the 10 sites was compared for the abattoirs, and sites were found to cluster into 2-4 homogenous groups. The means over sites of log10 MPNGU per cm2 for the abattoirs ranged from 1.52 to 2.64 and were unrelated to line speed.

Abattoirs↗
PubMed1982

Levels of adenosine 3',5' cyclic monophosphate and guanosine 3',5' cyclic monophosphate in single urine specimens collected from a large population of healthy subjects.

The levels of adenosine 3',5' cyclic monophosphate and guanosine 3',5' cyclic monophosphate have been measured in random urine specimens provided by 95 healthy volunteers with a view to assessing the importance of the effects of certain physiological factors on the cyclic nucleotide levels in this type of specimen, and to establish suitable reference ranges for future patient monitoring studies. Of the factors investigated, only the stage of the menstrual cycle was found to have a significant effect; even this variation was still within the overall normal reference range. Measurements of urine cyclic nucleotides were also made in relation to the method of specimen collection, handling, and storage. From these studies it was concluded that if the specimen is placed in a refrigerator within a few hours of collection and then transferred to a deep-freeze within 48 hours, these factors do not present any major problems for the subsequent assay of the cyclic nucleotides.

Adult↗
PubMed1976

Grid staining--a useful device.

A simple and disposable holder for electron microscope grids can be constructed from discs of silicon rubber. The discs (10 mm thick X 25 mm diameter) are scored 0.4 mm deep with a razor. Flexing the discs opens the scores for insertion of grids. Staining wells can be made from polyethylene snap-in vial tops by cutting away the nipple-like portion. After impaling the holders on the tips of a pair of forceps the grids can be washed by immersion. This holder is rigid, inert and inexpensive. It is of particular advantage for handling single-slotted grids.

Specimen Handling↗
PubMed1994

Detection of proliferating cell nuclear antigen in paraffin-embedded specimens is dependent on preembedding tissue handling and fixation.

Immunohistochemical detection of proliferating cell nuclear antigen (PCNA), a cell cycle-related protein used to estimate tumor growth fraction, is variable in formalin-fixed compared with methanol-fixed tissue specimens. This is assumed to result from conformational changes in the antigenic epitope induced by formaldehyde; therefore, to be susceptible to retrieval in archival specimens. In this study, formalin fixation reduced the intensity of staining and the number of positive cells to approximately 25% of those in methanol-fixed material. The washing of tissue specimens prior to methacarn fixation also reduced PCNA staining. Loss of staining was not restored after use of a commercial retrieval kit recommended for PCNA immunohistochemistry. Immunoblotting of formalin fixatives and saline washings after removal of tissue specimens consistently demonstrated the presence of PCNA-like activity in solution. We conclude that the exceptional solubility of PCNA is responsible for reduced immunostaining in formalin-fixed material, that the loss is irreversible, and that methanol or methacarn is the fixative of choice for PCNA immunohistochemistry.

Animals↗
PubMed1994

Fluoride release and effect on enamel softening by fluoride-treated and fluoride-untreated glass ionomer specimens.

The effect of fluoride application on fluoride release and enamel protection was studied using conventional and light-activated glass ionomers and composite. The specimens prepared from the materials were tested as (1) freshly mixed, (2) aged (29 days), (3) aged and fluoride treated, and (4) aged, fluoride treated, and aged (29 days). For fluoride application, the specimens were immersed in 1.2% NaF solution for 10 min and washed. After handling, the specimens were glued on polished bovine enamel slabs and immersed in lactic acid (pH 5.0) for 3 h. The microhardness of the enamel was measured before and after the acid immersion. Freshly mixed glass ionomers significantly prevented enamel softening. The effect disappeared (conventional glass ionomer) or decreased (light-activated glass ionomer) during aging, but was reestablished by fluoride application. After the subsequent 4 weeks of aging, no significant protective effect could be seen for either of the glass ionomers. The fluoride release, which was greatly increased by fluoride application, was still elevated after 4 weeks of aging for both materials.

Animals↗
PubMedDate not supplied

Gene rearrangements in malignant lymphomas.

The use of molecular methods to diagnose malignant lymphoma, while firmly established in reference centers, has not been well evaluated at the community level. A group of 57 specimens from patients with non-Hodgkin's lymphomas (NHL), lymphoid leukemias (LL), and a variety of other lymphoproliferative lesions with the Southern blot methodology have been studied by us. Molecular probes to the joining regions of the heavy (JH) and light (J kappa) immunoglobulin chains and the beta (J beta 1-2) chain of the T cell receptor genes were used. Gene rearrangements were detected in 90 percent of all NHL/LL with a 95 percent detection rate specifically for B-NHL/LL. In comparison, phenotypic analysis by immunoperoxidase stains favored a B phenotype in 75 percent of those cases, while flow cytometry assigned 63 percent of cases to a B cell lineage. Gene rearrangements were detected in four of six cases of T-NHL for a rate of 67 percent. The six other lymphoproliferative lesions included Hodgkin's disease, Castleman's disease, and a case of lymphoid hyperplasia. No rearrangements were detected in these specimens. The studies allowed development of increased confidence in the diagnosis of NHL/LL on ever smaller specimens. The availability of these studies has also helped establish a priority of handling all specimens so that the most appropriate studies can be performed to yield the most useful diagnostic information.

Gene Rearrangement↗