Internal quality assurance in a clinical virology laboratory. I. Internal quality assessment.

AIMS--In April 1991 an internal quality assessment scheme (IQAS) was introduced into the virology section of the Clinical Microbiology and Public Health Laboratory, Cambridge. The IQAS was established to identify recurring technical and procedural problems, to check the adequacy of current techniques, and to calculate the frequency of errors. METHODS--Between April 1991 and December 1993, 715 anonymous clinical serum samples were submitted to the laboratory to test 3245 individual procedures of diagnostic viral serology. RESULTS--A total of 485 (14.9%) procedural and 61 (1.9%) technical discrepancies were observed, the technical discrepancies mainly being recorded in complement fixation tests. Twenty two (0.7% of total procedures) of the technical discrepancies were diagnostically significant. CONCLUSIONS--Evaluation criteria developed with the introduction of IQAS to viral serology, and technical and procedural discrepancies are assessed. As yet, IQAS has not been introduced to other sections of the diagnostic virology laboratory (virus isolation, electron microscopy, immunofluorescence, and enzyme linked immunosorbent assays for viral and chlamydial antigens).     

Internal quality assurance in a clinical virology laboratory. II. Internal quality control.

AIMS--In April 1991 additional quality control procedures were introduced into the virology section of the Clinical Microbiology and Public Health Laboratory, Cambridge. Internal quality control (IQC) samples were gradually included in the serological assays performed in the laboratory and supplemented kit controls and standard sera. METHODS--From April 1991 to December 1993, 2421 IQC procedures were carried out with reference sera. RESULTS--The IQC samples were evaluated according to the Westgard rules. Violations were recorded in 60 of 1808 (3.3%) controls and were highest in the IQC samples of complement fixation tests (25/312 (8%) of controls submitted for complement fixation tests). CONCLUSIONS--The inclusion of IQC samples in the serological assays performed in the laboratory has highlighted batch to batch variation in commercial assays. The setting of acceptable limits for the IQC samples has increased confidence in the validity of assay results.     

Purification of ovocalyxin-32, a novel chicken eggshell matrix protein

The eggshell is a highly ordered structure resulting from the deposition of calcium carbonate and an organic matrix from the acellular uterine fluid. Characterization of the individual matrix components is necessary to determine their influence upon calcite crystal shape, size, and orientation during eggshell calcification. We have purified and sequenced a novel 32-kDa protein, ovocalyxin-32 (OCX-32), which is present at high levels in the uterine fluid during the terminal phase of eggshell formation, and is localized predominantly in the outer eggshell. Database searches identified expressed sequence tags (ESTs) whose alignment yielded the complete cDNA. OCX-32 protein possesses limited identity (32%) to two unrelated proteins: latexin, a carboxypeptidase inhibitor expressed in rat cerebral cortex and mast cells, and to a skin protein that is encoded by a retinoic acid receptor-responsive gene, TIG1. The timing of OCX-32 secretion into the uterine fluid suggests that it may play a role in the termination of mineral deposition.     

Evaluation of dry and wet transported intravaginal swabs in detection of Chlamydia trachomatis and Neisseria gonorrhoeae infections in female soldiers by PCR

Screening women for sexually transmitted diseases (STD) in nonclinic settings is highly desirable because many infections are asymptomatic. This is especially true for military women, for whom logistical, social, and other job-related obstacles present barriers to accessing medical care. We assessed the accuracy of intravaginal swabs transported by mail in a wet versus a dry state for PCR (Amplicor CT/NG test) detection of chlamydia and gonorrhea infections in a cross-sectional study of 793 active-duty military women attending an STD clinic. PCR tests of vaginal swabs (wet and dry) were compared to local clinical methods used on cervical swabs. Standard wet vaginal swab PCR testing detected more chlamydia (11.6%) than cervical enzyme immunoassay (9.3%). For detection of chlamydia using wet swabs, the sensitivity and specificity compared with adjudicated true positives were 94.6% (87 of 92) and 99.3% (696 of 701), respectively. Comparing dry swabs to true-positives for chlamydia, the sensitivity was 91.3% (84 of 92) and the specificity was 99.3% (696 of 701). Standard wet vaginal swab PCR detected more gonorrhea (3.3%) than routine cervical culture (2.1%). The sensitivity and specificity of PCR testing of wet swabs compared to true-positives (infected patients) were 96.3% (26 of 27) and 98.2% (752 of 766) for gonorrhea, respectively. For gonorrhea, the sensitivity and specificity of dry swabs compared to true-positives (infected patients) were 88.9% (24 of 27) and 98.3% (753 of 766), respectively. PCR testing of wet and dry transported intravaginal swabs to detect chlamydia and gonorrhea infections was an accurate diagnostic method for military women.     

Retroesophageal right subclavian artery with persistent ductus arteriosus

We report an adult male cadaver with persistence of the ductus arteriosus and a right retroesophageal artery. The retroesophageal artery was first appreciated as a retropharyngeal mass during the dissection of this area. Both the left and right vertebral arteries originated in normal fashion. The thoracic duct of our specimen drained into the junction of the left internal jugular and left subclavian veins. We believe this to be the first report of simultaneous right retroesophageal subclavian artery and patent ductus arteriosus. The anatomy and embryology of these two anomalies in the same specimen are discussed.     

The resolution of ambiguous stereoscopic matches by interpolation

Matching in stereograms made of horizontal rows of points can be described as follows: characteristic features, such as edges and gaps in the rows, have unambiguous matches in the two eyes, and these features are matched first. A plane interpolated between the positions in depth assigned to these features then guides the matching in the intervening sets of regularly spaced points which have potentially ambiguous matches. The intervening points are matched so that their disparity with respect to this interpolation plane is minimized. The "nearest disparity" rule describes matching for tilted interpolation planes as well as for fronto-parallel planes. While it is possible to construct stereograms which violate these matching rules, the rules work remarkably well in describing typical matching behaviour for many patterns.     

ACFAS Clinical Consensus Statement: Acute Achilles Tendon Pathology

Injuries to the Achilles tendon are a challenge to the foot and ankle surgeon. In recent years, research has led to a relative change in the way that many surgeons view acute Achilles tendon rupture. In an effort to fully evaluate these trends, as well as to evaluate all aspects of care for acute Achilles tendon rupture, the American College of Foot and Ankle Surgeons convened a panel of experts to create a clinical consensus statement to address selected aspects of care of the acute Achilles tendon injury.     

How does yoga reduce stress? A clinical trial testing psychological mechanisms

Yoga interventions can reduce stress, but the mechanisms underlying that stress reduction remain largely unidentified. Understanding how yoga works is essential to optimizing interventions. The present study tested five potential psychosocial mechanisms (increased mindfulness, interoceptive awareness, spiritual well-being, self-compassion and self-control) that have been proposed to explain yoga's impact on stress. Forty-two participants (62% female; 64% White) in a yoga program for stress reduction completed surveys at baseline (T1), mid-intervention (T2) and post-intervention (12 weeks; T3). We measured two aspects of stress, perceived stress and stress reactivity. Changes were assessed with paired t-tests; associations between changes in mechanisms were tested in residual change models. Only stress reactivity decreased, on average, from T1 to T3. Except for self-compassion, all psychosocial mechanisms increased from T1 to T3, with minimal changes from T2 to T3. Except for self-control, increases in each mechanism were strongly associated with decreases in both measures of stress between T1 and T2 and decreases in perceived stress from T1 to T3 (all p's < 0.05). Increased psychosocial resources are associated with stress reduction. Yoga interventions targeting these resources may show stronger stress reduction effects. Future research should test these linkages more rigorously using active comparison groups and larger samples.