Radionuclide left ventriculography with the slant hole collimator.

A 30 degrees slant-hole collimator was used during radionuclide ventriculography of the cardiac blood pool to improve imaging of the heart in both the modified left anterior oblique (MLAO) and right anterior oblique (RAO) views. In the MLAO view, with the holes slanted caudally, good separation between the left atrium and left ventricle was achieved, and the septum was displayed without foreshortening. In the RAO view with the collimator flat against the chest there was better resolution of the cardiac apex. The results of ejection fraction and wall motion analysis in these patients correlated well with contrast ventriculography (r=0.94). Combination of the slant-hole collimator, in vivo red blood cell labeling with stannous pyrophosphate, simultaneous collection of all phases of the cardiac cycle, and cine mode display, provide a practical system for the noninvasive measurement of left ventricular performance parameters.

Identification of the retinal pigment epithelium protein RET-PE2 as CE-9/OX-47, a member of the immunoglobulin superfamily.

PURPOSE: To identify the retinal pigment epithelium (RPE) surface antigen recognized by the monoclonal antibody RET-PE2. METHODS: A lambda bacteriophage complementary DNA (cDNA) expression library, representing the rat RPE cell line RPE-J, was constructed and screened with the RET-PE2 monoclonal antibody. Transient transfections of the RET-PE2 cDNA, immunofluorescence stainings of tissue sections or cultured cells, and Western blot analyses of tissue and cell detergent extracts served to prove that the protein resulting from expression of the cDNA is the RET-PE2 antigen. RESULTS: Three independent cDNAs were cloned that shared overlapping sequences. Sequence alignment with EMBL database entries revealed identity to the published cDNA of CE-9/OX-47, a member of the immunoglobulin superfamily. One of the clones encoded the entire open reading frame of CE-9. The expression pattern of the RET-PE2 antigen matched that of CE-9, which is widely expressed. Chinese hamster ovary cells transiently transfected with the RET-PE2 cDNA produced a membrane-localized protein that was recognized by RET-PE2 and CE-9 antibodies. CONCLUSIONS: The antibody RET-PE2 recognizes the CE-9/OX47 gene product, a transmembrane protein of the immunoglobulin superfamily. Contrary to results reported earlier, RET-PE2 immunoreactivity is widely distributed among different rat tissues--kidney, liver, and testis. In epithelia other than the adult RPE, it is confined to the basolateral plasma membrane. Its apical polarization in the RPE of adult rats supports earlier findings that some proteins that are basolateral in other epithelia exhibit reversed polarity in the RPE.

RET-PE10: a 61 kD polypeptide epitope expressed late during vertebrate RPE maturation.

PURPOSE: This study sought To learn more about the mechanisms that determine and maintain the differentiated state of the retinal pigment epithelium (RPE). METHODS: Monoclonal antibodies were raised against human RPE and used in conjunction with other antibodies. Immunocytochemical and biochemical analyses were performed on tissue sections and cells in culture. RESULTS: An RPE-specific epitope, RET-PE10, has been detected as a 61 kD cytoplasmic polypeptide in a variety of mammalian, amphibian, and avian species. In the rat, RPE-PE10 was expressed late in eye development, with a faint initial labelling of the RPE in central regions at postnatal day 9 (PN9) that increased to adult levels and extent of staining by PN14. RET-PE10 expression initially was present in overnight cultures of dissociated rat RPE cells but was lost rapidly from these cultures during the first week. Comparison of the staining patterns of RET-PE10 with those of various cytoskeletal elements suggests that RET-PE10 may be associated with part of the intermediate filament network. Culture of whole eyecups also resulted in a loss of RET-PE10 expression. RET-PE10 expression was normal in eyes of adult rd/rd mutant mice. CONCLUSIONS: RET-PE10 is a late-appearing marker of RPE differentiation. The results also suggest that the maintained expression of RET-PE10 depends upon extrinsic factors but that these do not include maintained contact with Bruch's membrane or light-induced retinal activity.

Nosocomial infections during extracorporeal membrane oxygenation.

OBJECTIVE: To examine trends in nosocomial infection associated with Extracorporeal Membrane Oxygenation (ECMO). DESIGN: Retrospective review of all patients who underwent ECMO over a 4-year period at our institution; specifically, examining reasons for placement and duration of time on ECMO, as well as nosocomial infections incurred while on or shortly after discontinuation of support. Infections were considered ECMO-related if the organism was recovered on support or within 7 days from decannulation. Analyses were performed utilizing Pearson's chi-square for dichotomous factors and t-tests for continuous factors. RESULTS: Of 141 patients requiring ECMO support, 90 (64%) survived to hospital discharge. Indication for support included circulatory failure (53%) and non-cardiac (47%). Twenty-six percent of patients developed infections on ECMO. Organisms isolated included: bacterial 20 (54%), fungal 10 (27%), mixed five (14%) and viral two (5%). Infection sites included: blood 13 (35%), urine nine (24%), mixed eight (22%), wound five (14%) and lung two (5%). Seventy-eight percent of infections noted occurred in cardiac patients. Patients with nosocomial infections were supported for a median of 169 h (range, 84-936 h), versus those without nosocomial infection [146 h (range, 50-886 h); P<0.001]. Procedures on ECMO were associated with an increased risk of infection (P<0.001) as was the presence of an open chest (P<0.025). CONCLUSIONS: The incidence of infection in ECMO patients at our institution has not increased significantly since our previous study. Cardiac patients have increased risk for nosocomial infection while on ECMO, which may be in part due to longer cannulation times, as well as increased likelihood of undergoing major procedures or having an open chest.

A computer-assisted assay for mouse sperm hyperactivation demonstrates that bicarbonate but not bovine serum albumin is required.

Mammalian sperm hyperactivation (HA) is a change in motility that accompanies capacitation (CAP) and is dependent on calcium (Ca) (Yanagimachi and Usui, Exp Cell Res 89:161, 1974). HA may be important for transport through the female tract and/or for fertilization. To develop an objective and quantitative assay for HA in individual mouse sperm, a computer-assisted motion-analysis system was used to describe sperm translational movements. To determine which movements were characteristic of HA, Ca-dependent motility was identified. This was done by incubating sperm with or without calcium (Ca+ or Ca- sperm, respectively), and determining the range of values for each motility parameter that was present only among Ca+ sperm. To do this, we compared frequency distributions of motility parameter values at the time of maximal CAP (90 min). CAP was monitored by measuring the level of in vitro fertilization and by evaluating the pattern of chlortetracycline binding to individual sperm heads [Ward and Storey, Dev Biol 104:287, 1984]. Two Ca-dependent motility subgroups were apparent: 1) a "slow-speed" subgroup with a curvilinear velocity (Vc) less than 169 microns/sec that had none of the characteristics expected of HA sperm; and 2) a subgroup with higher speeds (Vc greater than 169 microns/sec) and wider-amplitude head movements as measured by curvilinear progressiveness ratio (PRc less than 0.56). The latter subgroup was selected as HA, since the frequencies and time course were similar to those for CAP in the same population. Two media components known to be important for CAP, bicarbonate and bovine serum albumin (BSA) were then tested to determine whether they were necessary for HA. Incubation of sperm without bicarbonate prevented HA, but omitting BSA did not affect HA during the first 3 hrs. These data suggest that HA is not tightly coupled with CAP.

Expression of the cell surface antigens RET-PE2 and N-CAM by rat retinal pigment epithelial cells during development and in tissue culture.

Invagination of the optic vesicle to form the optic cup results in the formation of two apposed layers of neuroepithelium which follow divergent developmental pathways. Changes in the expression of cell surface molecules may be either the cause or result of important inductive signals during this process. We have used immunological reagents to study the expression of two molecules in the rat: the neural cell adhesion molecule N-CAM, and a cell membrane-associated protein which is specific for pigment epithelium in the adult, RET-PE2. Both N-CAM and RET-PE2 are present in both layers of the optic cup at embryonic age E13, but they become restricted to inner retina and pigment epithelium, respectively, by E17 and maintain that pattern of expression in the normal adult. Culture of pigment epithelial cells results in the reexpression of N-CAM and the continued expression of RET-PE2. Western blotting reveals that the size and relative proportions of the 180- and 140-kDa N-CAM molecules synthesized by rat pigment epithelial cells in vitro differ from that made by rat brain, retina and liver. Embryonic RPE N-CAM contains the sulfated carbohydrate recognized by the HNK-1 antibody, but this epitope was not present on N-CAM synthesized by cultured RPE cells. The reexpression of an embryonic antigen when placed in culture suggests that pigment epithelial cells retain some degree of plasticity in the adult state.

Incubation of mouse sperm with lactate delays capacitation and hyperactivation and lowers fertilization levels in vitro.

Mouse sperm were incubated in medium with or without 24 mM lactate and assessed for 1) motility characteristics including hyperactivation--a computer-assisted motion analysis system was used; 2) capacitation--a chlortetracycline fluorescent dye binding assay was used; and 3) ability to penetrate oocytes. Lactate affected all aspects of motility and delayed the rates of both hyperactivation and capacitation. When a concentration of 8 x 10(3) sperm/ml was used for insemination in vitro, sperm preincubated 60-90 minutes in medium with lactate prior to insemination in lactate-free medium fertilized fewer oocytes than did sperm preincubated in lactate-free medium. Use of a calcium-sensitive electrode demonstrated that lactate chelated appreciable amounts of calcium in the medium. Capacitation was assayed in sperm incubated 60 minutes in medium with various concentrations of lactate or CaCl2. When medium containing lactate was compared to medium without lactate but having a similar level of free calcium, the level of capacitation of sperm incubated with lactate was less than half that of sperm incubated without lactate. These results demonstrate that including 24 mM lactate in the medium can have detrimental effects on mouse sperm hyperactivation and capacitation. The detrimental effects on capacitation are partly but not completely due to the chelation of calcium by lactate.

The polarity of the plasma membrane protein RET-PE2 in retinal pigment epithelium is developmentally regulated.

The retinal pigment epithelium (RPE) differs from other epithelia in that the apical surface is not free; instead, it interacts with both photoreceptors and a specialized extracellular material, the interphotoreceptor matrix. Biochemical characterization of the apical and basolateral surfaces of RPE in adult rat eye cups, using a novel in situ biotinylation assay, revealed very different protein compositions and identified a major surface antigen, RET-PE2, with a predominantly apical distribution (approximately 74%). The apical polarity of RET-PE2 was confirmed by immunofluorescence and laser scanning confocal microscopy. In striking contrast, RET-PE2 antigen was preferentially basolateral in primary cultures derived from adult rat RPE and in an immortalized RPE cell line (RPE-J). Under all conditions, RET-PE2 was highly soluble in Triton X-100 (> 81% at 4 degrees C), suggesting that its redistribution was not dependent on changes in cytoskeletal interactions. Analysis of the localization of RET-PE2 in normal rats at postnatal (PN) days 1, 7, and 14 indicated that RET-PE2 redistributes from predominantly basolateral to predominantly apical during that time. Since photoreceptors develop during the first two weeks after birth in the rat, our results suggest that the apical redistribution of RET-PE2 is dependent on the establishment of adult interactions between the RPE and the neural retina and/or the interphotoreceptor matrix, either via direct contacts or through alterations in the intracellular sorting patterns of RPE cells.

Helical CTPA in the investigation of pulmonary embolism: a 6-year review.

AIM: To assess the change in practice and resulting diagnostic outcome in the radiological investigation of pulmonary embolism (PE) since the introduction of helical CTPA in a large teaching hospital. MATERIALS AND METHODS: A retrospective review was undertaken of all radiological investigations performed over a 6-year period before and after the introduction of CTPA (protocols 1 and 2, respectively) as an integral part of the imaging protocol in the investigation of clinically suspected PE. The total numbers and results of all investigations are assessed for each protocol. RESULTS: A substantial increase in both the total number of patients and the number of investigations performed for the investigation of PE since the introduction of CTPA occurred. Five hundred and twenty-six patients underwent 617 investigations in 1995-1996, and 760 patients underwent 805 investigations in 2001-2002. There was a significant decrease in the number of investigations per patient, 1.17 in 1995-1996 versus 1.06 in 2001-2002. Primary investigation showed a significant decrease in indeterminate examinations from 25.7 to 8.5% and an increase in positive results for PE from 18 to 24%. CONCLUSION: In the study population there was a significant increase in the number of patients being investigated for PE, with a decrease in both the number of non-diagnostic investigations and the total investigations per patient since the introduction of helical CTPA. This is probably due to the ready availability of a new imaging technique and physicians awareness that CTPA has significantly improved specificity, which encourages the referral of patients for investigation.

Cardiopulmonary resuscitation and contrast media reactions in a radiology department.

AIM: To assess current knowledge and training in the management of contrast media reactions and cardiopulmonary resuscitation within a radiology department. MATERIALS AND METHODS: The standard of knowledge about the management of contrast media reactions and cardiopulmonary resuscitation among radiologists, radiographers and nurses were audited using a two-section questionnaire. Our results were compared against nationally accepted standards. Repeat audits were undertaken over a 28-month period. Three full audit cycles were completed. RESULTS: The initial audit confirmed that although a voluntary training programme was in place, knowledge of cardiopulmonary resuscitation techniques were below acceptable levels (set at 70%) for all staff members. The mean score for radiologists was 50%. Immediate changes instituted included retraining courses, the distribution of standard guidelines and the composition and distribution of two separate information handouts. Initial improvements were complemented by new wallcharts, which were distributed throughout the department, a series of lectures on management of contrast reactions and regular reviews with feedback to staff. In the third and final audit all staff groups had surpassed the required standard. CONCLUSION: Knowledge of contrast media reactions and resuscitation needs constant updating. Revision of skills requires a prescriptive programme; visual display of advice is a constant reminder. It is our contention all radiology departmental staff should consider it a personal duty to maintain their resuscitation skills at appropriate standards.

Thymineless death in polA+ and polA- strains of Escherichia coli.

The extreme sensitivity of polA(-) cells to thymineless death is due, primarily, to the absence of an extended lag prior to the commencement of death. Once thymineless death has commenced, the rate in polA(-) cells is only slightly faster than in polA(+) cells.

Use of equilibrium (gated) radionuclide ventriculography to quantitate left ventricular output in patients with and without left-sided valvular regurgitation.

We examined the accuracy with which left ventricular output can be estimated by equilibrium radionuclide ventriculography. After red blood cells were labeled in vivo, we measured left ventricular end-diastolic and end-systolic count rates and the count rate in 5 ml of the patient's blood. After estimating the average ratio of counting efficiency for the left ventricle to counting efficiency for the blood sample (Elv/Es) in six patients, we calculated left ventricular output in 26 other patients as (left ventricular activity ejected per minute divided by activity per liter of blood) divided by the previously estimated Elv/Es. Radionuclide left ventricular output closely approximated Fick cardiac output (r = 0.94) in patients without mitral or aortic regurgitation and exceeded Fick cardiac output in all patients with valvular regurgitation. Regurgitant fraction, calculated as the difference between the radionuclide and Fick outputs divided by the radionuclide output, correlated with the severity of of regurgitation as assessed angiographically. The equilibrium radionuclide ventriculogram is an excellent means for noninvasive estimation of left ventricular output.

Regional ejection fraction: a quantative radionuclide index of regional left ventricular performance.

Radionuclide measurements of regional left ventricular ejection fraction were evaluated as a quantitative index of regional left ventricular function. Left ventricular regional ejection fractions were derived from background-corrected, time-activity curves in 43 patients assessed by both gated equilibrium radionuclide angiocardiography and left ventricular contrast angiography. From a single, modified left anterior oblique projection, the regional change in background corrected counts was determined in each of three anatomic regions. The normal range for regional radionuclide ejection fraction was determined in 10 patients with normal contrast ventriculograms and without obstructive coronary artery disease at coronary arteriography. Regional ejection fraction was compared with percent segmental axis shortening and extent of akinetic segments in corresponding regions of the contrast ventriculogram. Radionuclide and roentgenographic methods were in agreement as to the presence or absence of abnormal wall motion in 83 of 99 left ventricular regions (84%) in 33 patients evaluated prospectively. Comparison of regional ejection fraction demonstrated significant differences between regions with roentgenographically determined normokinesis (75 +/- 3%, mean +/- SEM), hypokinesis (44 +/- 3%, p less than 0.0005) and akinesis (24 +/- 5%, p less than 0.005). We conclude that the left ventricular regional ejection provides a reliable quantitative assessment of regional left ventricular performance.

An unusual presentation of neonatal adrenal hemorrhage.

Case report of a neonate presenting within 1 h of birth with right side scrotal swelling and a dusky skin discoloration thought clinically to be a hydrocele or testicular torsion. Ultrasound examination demonstrated bilateral hydroceles, more prominent on the right, scrotal oedema and a perinephric loculated fluid collection secondary to right adrenal hemorrhage. We review the ultrasound appearance of the normal and haemorrhagic neonatal adrenal and discuss the differential diagnosis of both neonatal adrenal lesions and scrotal swellings. The role and benefits of ultrasound in the primary diagnosis and management of neonatal adrenal hemorrhage is emphasized.

Recurrence of dialysis shunt pseudoaneurysm following percutaneous thrombin embolization.

We report an unusual case of a 58-year-old woman on maintenance hemodialysis who presented with an iatrogenic radial artery pseudoaneurysm proximal to a Cimino-Brescia fistula. The pseudoaneurysm was not amenable to ultrasonographic compression due to the vascular anatomy. The pseudoaneurysm recurred despite initial successful response to two direct injections of thrombin on separate occasions. We highlight the role of ultrasound and thrombin injection in the treatment of pseudoaneurysm and emphasize the need for follow-up ultrasound examination to monitor recurrence.

Visual expectation and dimensions of infant information processing.

Visual expectation was assessed in 103 black 6.5-month-olds using Haith, Hazan, and Goodman's paradigm and related to performance on standard developmental assessments and tests of information processing skill. As expected, percent anticipations was higher and RT lower than in 3.0-month-olds previously tested. Split-half and left-right correlations for the RT measures were moderate and similar to those previously reported, as was split-half reliability for percent anticipations. The 2 RT measures were related to fixation duration on both visual recognition memory (VRM) and cross-modal transfer, suggesting moderate cross-task and cross-age consistency in processing speed. Percent anticipations and baseline RT each contributed independently to the prediction of VRM novelty preference. Data from a factor analysis suggested 3 dimensions of cognitive function: processing speed, developmental level, and memory/attention. These findings suggest that the visual expectation paradigm provides a reliable new approach for assessing cognitive processing efficiency and attention during infancy.