Chorea as a presenting feature of variant Creutzfeldt-Jakob disease.

We report on a patient with pathologically proven variant Creutzfeld-Jakob disease in whom chorea was a presenting feature of the disease, and was unaccompanied by the typical prodrome of psychiatric disturbance or sensory symptoms.     

The impact of lower urinary tract symptoms on general health status and on the use of prostatectomy

Our objective was to determine the extent to which lower urinary tract symptoms affect the general health status of men and contribute to the decision to undergo surgery. A cross-sectional population survey using postal questionnaires was conducted in the North West Thames health region, followed by a prospective cohort study of men undergoing prostatectomy (North West Thames and Oxford regions). The subjects in the first survey were 221 men aged 55 and over with previously reported mild, moderate or severe urinary symptoms; subjects in the second study were 388 men undergoing prostatectomy. Main outcome measures were selfreported symptom severity, bothersomeness and general health status (Nottingham Health Profilie, Part 1). The response rate among eligible responders in the population survey was 85.7%. Increasing symptom severity was associated with worsening NHP scores for energy, emotional reactions, sleep and physical mobility (p<0.01). Increasing bother-someness of symptoms was associated with emotional reactions, sleep and pain (p<0.05). Men undergoing surgery reported worse health status than men in the population with the same severity of symptoms as regards emotional reactions, energy and pain. For a given level of symptom severity, the impact of those symptoms on aspects of a man's general health status may be the determinant of seeking and undergoing surgery. Greater understanding of the factors that affect a man's response to his symptoms is needed in interpreting the decision to seek and accept treatment.     

The imprecision of stereopsis

In comparison to lateral judgments of distance, stereoscopic judgments are not precise. Although stereoacuity thresholds for targets presented in the fixation plane can equal the best thresholds for the monocular hyperacuities, i.e. a few sec arc, the increment thresholds for disparity are substantially larger than the increment thresholds for lateral separation (width). We measured the minimum detectable change in the three-dimensional distance separating two features, one presented in the fixation plane, and the other some distance in front of it, i.e. with a significant standing disparity between the two features. For briefly-presented targets (150 msec), the Weber fraction for disparity was 10-20% over the range from 1 to 20 min arc, while the Weber fraction for width was only 2-3% under comparable conditions. The disparity thresholds were substantially improved for a longer duration target (1000 msec), but they were still a factor of two worse than the monocular width thresholds. In a related experiment, the vernier acuity for a standard vernier target was profoundly degraded by pairing the offset upper line presented to one eye with a disparate line in the other eye; the vernier threshold was elevated for disparities ranging from 3 to 30 min arc. This finding shows that the more precise monocular signals are actively suppressed in fused or partially-fused stereoscopic images.     

Specificity of cone mechanisms in lateral interaction

1. The increment threshold for a brief, small probing light flash was used as an indicator of the state of adaptation of the human fovea. It shows that illumination of a zone up to 7 min of arc in diameter desensitizes the retina and that the additional illumination of a surrounding zone acts to counteract the desensitization.

2. The red and green colour mechanisms were isolated by selecting light of appropriate wave-lengths for the adaptation and the increment stimuli and it was demonstrated that the desensitizing and sensitizing adaptation zones exist within each mechanism.

3. Using the constancy of the increment threshold for a brief, small probing flash as a null-indicator for equivalence of annuli of various wave-lengths to produce a given amount of sensitization, the action spectrum for the laterally interacting region was obtained for both the red and the green mechanisms.

4. For the red mechanism, the surrounding sensitizing zone has the action spectrum also of the red mechanism. For the green mechanism the surrounding sensitizing zone has a green action spectrum.

     

Ultrastructure of Ehrlichia canis

The ultrastructure of Ehrlichia canis was examined in both pulmonary mononuclear cells and in monocytes cultured from an infected dog. The cytoplasmic inclusions, or morulae, of E. canis consisted of a membrane-lined vacuole-containing elementary bodies which varied in size and number. The elementary bodies were bound by two trilamellar membranes. The organism shared morphological properties of both the genus Rickettsia and genus Chlamydia.     

Adherence and entry of Borrelia burgdorferi in Vero cells.

Adherence to and entry of the parasite into the host is one of the essential elements of microbial pathogenicity. We investigated the adherence to and entry into primate kidney epithelial (Vero) cells of Borrelia burgdorferi by radiolabelling techniques, immunofluorescence and electronmicroscopy. The attachment to and subsequent entry of both untreated and heat (50 degrees C)-treated B. burgdorferi into Vero cells occurred at cell-surface sites associated with aggregated coated pits. In contrast, there was minimal attachment of spirochaetes heated at 60 degrees C. Radiometric studies showed that, with untreated cells, there was incorporation of both 14C-glucose-1-phosphate and 14C-thymidine, whereas with the 50 degrees C-treated spirochaetes only glucose-1-phosphate was incorporated, and with the 60 degrees C-treated spirochates neither radionuclide was incorporated. Spirochaetes heated at 50 degrees C or 60 degrees C did not grow at 35 degrees C in culture medium. These results suggest that the presence of certain metabolic activities of the spirochaete but not viability (ability to grow) are necessary for the attachment process. After entry of untreated B. burgdorferi, most of the spirochaetes were either free in the cytoplasm or tightly bound to the host membrane. In contrast, 50 degrees C-treated spirochaetes remained bound to host membrane in large phagosome-like vesicles.     

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).