Surgical and Radiology Trainees' Proficiency in Reading Mammograms: the Importance of Education for Cancer Localisation

Medical imaging with mammography plays a very important role in screening and diagnosis of breast cancer, Australia's most common female cancer. The visualisation of cancers on mammograms often forms a diagnosis and guidance for radiologists and breast surgeons, and education platforms that provide real cases in a simulated testing environment have been shown to improve observer performance for radiologists. This study reports on the performance of surgical and radiology trainees in locating breast cancers. An enriched test set of 20 mammography cases (6 cancer and 14 cancer free) was created, and 18 surgical trainees and 32 radiology trainees reviewed the cases via the Breast Screen Reader Assessment Strategy (BREAST) platform and marked any lesions identifiable. Further analysis of performance with high- and low-density cases was undertaken, and standard metrics including sensitivity and specificity. Radiology trainees performed significantly better than surgical trainees in terms of specificity (0.72 vs. 0.35; P < 0.01). No significant differences were observed between the surgical and radiology trainees in sensitivity or lesion sensitivity. Mixed results were obtained with participants regarding breast density, with higher density cases generally having lower performance. The higher specificity of the radiology trainees compared to the surgical trainees likely represents less exposure to negative mammography cases. The use of high-fidelity simulated self-test environments like BREAST is able to benchmark, understand and build strategies for improving cancer education in a safe environment, including identifying challenging scenarios like breast density for enhanced training.

Chronic nasal dysfunction: A clinical case illustrating the concept in practice

INTRODUCTION

We illustrate the diagnostic method for chronic nasal dysfunction by an observation in which the clinical history was compared to preoperative responses on the DyNaChron self-administered questionnaire, with ENT interpretation of the sinonasal CT scan preceding and guiding nasal endoscopy.

CASE REPORT

The initial suspicion of rhinitis medicamentosa was transformed by the radiological and endoscopic findings of chronic respiratory rhinitis signs. Prick tests showing sensitivity to dust mites then suggested an allergic origin of the mucosal inflammation, which affected neither the olfactory nose nor the paranasal sinuses. A septal deviation hampering visualization of the right ethmoidal reliefs completed the clinical picture. Inferior turbinate hypertrophy secondary to allergic inflammation could have been aggravated by prolonged daily use of nasal vasoconstrictors. Failure of medical treatment combining nasal lavage, topical corticosteroids and an attempt at weaning led to effective medical and surgical management combining septoplasty, bilateral inferior turbinoplasty, continuation of topical corticosteroids and initiation of allergen immunotherapy. In addition to complete relief of nasal obstruction and abandonment of nasal vasoconstrictors, improved sense of smell completed the restoration of nasal comfort.

DISCUSSION

It is helpful to conceive the nose as being anatomically and pathophysiologically a triple organ and to evaluate therapy in terms of improvement in each symptom.

Improving the design and conduct of aquatic toxicity studies with oils based on 20 years of CROSERF experience

Laboratory toxicity testing is a key tool used in oil spill science, spill effects assessment, and mitigation strategy decisions to minimize environmental impacts. A major consideration in oil toxicity testing is how to replicate real-world spill conditions, oil types, weathering states, receptor organisms, and modifying environmental factors under laboratory conditions. Oils and petroleum-derived products are comprised of thousands of compounds with different physicochemical and toxicological properties, and this leads to challenges in conducting and interpreting oil toxicity studies. Experimental methods used to mix oils with aqueous test media have been shown to influence the aqueous-phase hydrocarbon composition and concentrations, hydrocarbon phase distribution (i.e., dissolved phase versus in oil droplets), and the stability of oil:water solutions which, in turn, influence the bioavailability and toxicity of the oil containing media. Studies have shown that differences in experimental methods can lead to divergent test results. Therefore, it is imperative to standardize the methods used to prepare oil:water solutions in order to improve the realism and comparability of laboratory tests. The CROSERF methodology, originally published in 2005, was developed as a standardized method to prepare oil:water solutions for testing and evaluating dispersants and dispersed oil. However, it was found equally applicable for use in testing oil-derived petroleum substances. The goals of the current effort were to: (1) build upon two decades of experience to update existing CROSERF guidance for conducting aquatic toxicity tests and (2) to improve the design of laboratory toxicity studies for use in hazard evaluation and development of quantitative effects models that can then be applied in spill assessment. Key experimental design considerations discussed include species selection (standard vs field collected), test substance (single compound vs whole oil), exposure regime (static vs flow-through) and duration, exposure metrics, toxicity endpoints, and quality assurance and control.

Continued Sex-Differences in the Rate and Severity of Knee Injuries among Collegiate Soccer Players: The NCAA Injury Surveillance System, 2004-2009

We extend previous analyses and examined sex-differences in the rate and severity of knee injuries among collegiate soccer players between 2004 and 2009. Data from the National Collegiate Athletic Association Injury Surveillance System (NCAA ISS) were used to calculate injury incidence density (ID) per 1 000 athletic exposures (AE). Multivariable regression modeling then tested the relation between sex and knee injury incidence and severity among all injured soccer players, while controlling for contact, setting, and division level, as well as for the interactions among these variables. The rate of knee injuries was 1.19 per 1 000 AEs in women and 0.91 per 1 000 AEs in men (RR=1.31, 95% Wald CI=[1.16, 1.47]). In the multivariable modeling, women continued to experience significantly higher odds of knee injury compared with men (aOR=1.44, 95% CI=[1.27,1.63]). Also, the adjusted odds of a knee injury that resulted in surgery remained higher in women compared with men (aOR=1.61 (1.00, 2.58), as well as the amount of time lost from participation (beta=0.129; p=0.05). Given the prominence of soccer play in the United States, continued efforts to evaluate and improve knee injury prevention practices and policies may be especially important for female players.

Attenuation of direct sound and the contributions of early reflections within symphony orchestras

On concert hall stages the sound traveling between players consists of the direct sound, a floor reflection and early reflections off players and objects on stage such as instruments and music stands. In smaller music ensembles, the acoustic communication between players is normally good. In larger ensembles, there is a similar situation for short distances between players. However for ensembles like a symphony orchestra, the number of players on stage results in large distances between some players with many other players sitting in between, which block the direct sound and floor reflection paths. This study investigates the sound levels on stage with and without a large orchestra present, in the absence of any stage enclosure. Sound levels within the octave bands 63-2000 Hz on an empty stage were studied analytically, while sound levels over the same frequency range with players present were investigated in a 1:25 scale model, both without and with risers on stage. The main results are presented in terms of the attenuation introduced by the orchestra, with linear models developed to describe behavior for the octave bands 500-2000 Hz.

Haemodynamically unstable pulmonary embolism in the RIETE Registry: systolic blood pressure or shock index?

Patients with acute pulmonary embolism (PE) presenting with haemodynamic instability have the worst prognosis. However, what is understood by haemodynamic instability has not been clearly defined. The Registro Informatizado de la Enfermedad Tromboembólica (RIETE) is an ongoing registry of consecutive patients with symptomatic, objectively confirmed, acute deep vein thrombosis or PE. The present authors compared the predictive value of a systolic blood pressure (SBP) value of <100 mmHg and <90 mmHg and the shock index (cardiac frequency divided by SBP) on 30-day mortality in consecutive patients with PE. As of May 2006, 6,599 patients with PE were enrolled in the study. Of these, 417 (6.3%) died within 30 days: 153 of the initial PE, 29 of recurrent PE and 235 due to other causes. Of the 417 individuals who died, 127 (30%) had a positive shock index, 60 (14%) had SBP <100 mmHg and 33 (7.9%) had SBP <90 mmHg. On multivariate analysis any of the three parameters were independently associated with an increased mortality. The shock index had a higher sensitivity (30.5 versus 14.4 and 7.9% for SBP <100 mmHg and <90 mmHg, respectively) but lower specificity (86.3 versus 93.0 and 96.6). All three measures of haemodynamic instability are independent predictors of 30-day mortality. However, while the shock index had the highest sensitivity, a systolic blood pressure value <90 mmHg had the highest specificity.

Association between tPA therapy and raised early matrix metalloproteinase-9 in acute stroke

BACKGROUND

Matrix metalloproteinase-9 (MMP9) is expressed in acute ischemic stroke and up-regulated by tissue plasminogen activator (tPA) in animal models. The authors investigated plasma MMP9 and its endogenous inhibitor, tissue inhibitor of metalloproteinase (TIMP1), in tPA-treated and -untreated stroke patients.

METHODS

Nonstroke control subjects and consecutive ischemic stroke patients presenting within 8 hours of onset were enrolled. Blood was sampled within 8 hours and at 24 hours, 2 to 5 days and 4 to 6 weeks. MMP9 and TIMP1 were analyzed by ELISA and gel zymography.

RESULTS

Fifty-two cases (26 tPA treated, 26 tPA untreated) and 27 nonstroke control subjects were enrolled. Hyperacute MMP9 was elevated in tPA-treated vs tPA-untreated patients (medians 43 vs 28 ng/mL; p = 0.01). tPA therapy independently predicted hyperacute MMP9 after adjustment for stroke severity, volume, and hemorrhagic transformation (p = 0.01). There was a trend toward lower hyperacute TIMP1 levels in tPA-treated vs tPA-untreated patients (p = 0.06). Hyperacute MMP9 was correlated to poor 3-month modified Rankin Scale outcome (r = 0.58, p = 0.0005).

CONCLUSION

Tissue plasminogen activator independently predicted plasma matrix metalloproteinase-9 (MMP9) in the first 8 hours after human ischemic stroke. As MMP9 may be an important mediator of hemorrhagic transformation, alternative thrombolytic agents or therapeutic MMP9 inhibition may increase the safety profile of acute stroke thrombolysis.

Inflammation, Homocysteine, and Vitamin B6 Status After Ischemic Stroke

BACKGROUND AND PURPOSE

Epidemiological studies have described an association between low vitamin B6 (measured as pyridoxal 5'-phosphate [PLP]) and ischemic stroke, independent of homocysteine (tHcy). We investigated B6 status, tHcy, and inflammation (measured by C-reactive protein [CRP]) in patients with stroke and controls.

METHODS

Consecutive cases with new ischemic stroke were compared with matched controls. Fasting tHcy, PLP, and CRP were measured.

RESULTS

The adjusted odds ratio of low PLP in the highest compared with the lowest CRP quartile was 16.6 (2, 139.9, P=0.01). Age, CRP, supplemental vitamin use, and albumin were independent predictors of PLP (P<0.05 for all). No relationship was observed between CRP and tHcy.

CONCLUSIONS

The relationship between inflammation and low B6 status may partially explain the findings of previous epidemiological studies.

Stroke in young patients with hyperhomocysteinemia due to cystathionine beta-synthase deficiency

BACKGROUND

Although hyperhomocyst(e)inemia (Hyper-Hcy) may predispose to atherosclerosis and venous thrombosis, the mechanisms of stroke associated with Hyper-Hcy are not defined.

METHODS

Clinical and biochemical phenotypes and genetic features of three unrelated patients with premature stroke and severe Hyper-Hcy due to cystathionine beta-synthase (CBS) deficiency are described. Plasma Hcy and amino acids were measured by fluorescence polarization immune assay and ion exchange chromatography. Analysis of the CBS and methylenetetrahydrofolate reductase genes was performed by restriction enzyme digestion and sequence analysis.

RESULTS

Two of the three index cases had no known diagnosis of homocystinuria and initially presented with embolic cerebral and retinal infarction in mid-adulthood. Mechanisms of cerebrovascular disease were carotid intraluminal thrombosis, arterial dissection, and possible cardiac embolism. Family screening revealed additional members with clinically silent homocystinuria and severe Hyper-Hcy. Excluding tall stature in two individuals, all had mild phenotypes, without classic findings of CBS deficiency. Plasma total and free Hcy, methionine, and urine Hcy were elevated. Genotyping revealed heterozygous CBS mutations (I278T, D444N, G307S) in affected individuals.

CONCLUSION

Artery-to-artery embolism and dissection may cause stroke in young adults with homocystinuria. The results also support a rationale for screening for Hyper-Hcy in young adults with stroke without a phenotype suggestive of classic homocystinuria.

Acute right ventricular failure during aortic root replacement: intraoperative diagnosis and treatment

The scope of this article is to report on a patient who underwent a Bentall procedure for type A aortic dissection. Right ventricular (RV) failure developed immediately after completion of the operation. The etiology was determined by using transit time flow measurement (TTFM), an ultrasound-based technique which demonstrated the absence of blood flow to the right coronary artery. This allowed for early and effective treatment, which was followed by a successful outcome.

Expression of chick Tbx-2, Tbx-3, and Tbx-5 genes during early heart development: evidence for BMP2 induction of Tbx2

Expression patterns of Tbx2, -3, and -5 genes were analyzed during chick embryonic heart development. Transcripts of these three cTbx genes were detected in overlapping patterns in the early cardiac crescent. cTbx2 and cTbx3 expression patterns closely overlapped with that of bmp2. cTbx5 expression diverged from cTbx2 and bmp2 during the elaboration and folding of the heart tube. In comparison, cTbx2 expression overlapped significantly with that of bmp2 and bmp4 during all stages of heart development and during later embryonic stages, suggestive of a specialized role for Tbx2 in septation. Coexpression of cTbx 2 and cTbx3 genes with bmp2 transcripts raised the possibility that these cTbx genes might be downstream bmp2 targets. Application of bmp2 selectively induced cTbx2 and cTbx3 expression in noncardiogenic embryonic tissue, and the bmp antagonist Noggin down-regulated cTbx2 gene activity. Moreover, the appearance of murine mTbx2 was blocked in bmp2 null mouse embryos. cTbx2 and to a lesser extent cTbx3 gene activity appears to be directed by BMPs during early cardiogenesis.

Requirement for BMP and FGF signaling during cardiogenic induction in non-precardiac mesoderm is specific, transient, and cooperative

We previously reported that combined treatment with bone morphogenetic protein-2 (BMP-2) and fibroblast growth factor-4 (FGF-4) induces cardiogenic events culminating in full cardiac differentiation of non-precardiac mesoderm explanted from stage 6 avian embryos (Lough et al. [1996] Dev. Biol. 178:198-202.). To elucidate the respective functions of BMP and FGF in initiating and maintaining the cardiogenic process, we have used these ectopic cells as a cardiac specification model to ascertain requirements for growth factor specificity and extent of application, as well as induction of cardiac transcription factors. The inability of some BMP isoforms to replace the inductive activity of BMPs-2/4 indicated a specific requirement for this signaling pathway; moreover, neither activin-A nor insulin, which support terminal differentiation of precardiac mesoderm, nor leukocyte inhibitory factor (LIF), which promotes hypertrophy in cardiac myocytes, could replace BMP's cardiogenic activity. A similarly specific requirement for FGF-2/4 signaling was revealed since neither FGF-7, activin-A nor insulin could replace this activity. The effect of both factors was concentration-dependent; maximal incidence of explant differentiation for each occurred at 50 ng/ml. Surprisingly, the majority of explants treated with high BMP levels (250 ng/ml) exhibited a non-cardiac phenotype that was characterized by intense expression of alkaline phosphatase, suggesting differentiation toward an alternative mesodermal phenotype. Experiments to assess the duration of exposure to each factor that was required revealed that while exposure to BMP and FGF during only the initial 30 min of a 48-hr culture period was sufficient to induce cardiogenesis in a significant percentage of explants, 100% incidence of explant differentiation was obtained only when FGF treatment was restricted to the first 30 min and BMP was continuously present during the 48-hr culture period. Treatment with both growth factors was required to induce the cardiac transcription factors cNkx-2.5 and SRF; neither mRNA was induced by BMP or FGF alone. These findings indicate that: (1) specific members of the BMP and FGF families are required to induce cardiogenesis in non-precardiac mesoderm; (2) BMPs-2/4 may function as a morphogen; (3) brief application of both factors can induce cardiogenesis in a modest number of explants whereas (4) 100% incidence of explant differentiation can only be attained by brief FGF treatment combined with continuous BMP treatment and (5) both factors are necessary to induce downstream cardiac transcription factors. These findings are interpreted in terms of these factors' possible roles during cardiac specification and differentiation.

Fluorescence in situ hybridization analysis of the fos/jun ratio in the ageing brain

We have examined the expression of the fos and jun genes in the cerebellum of the rat brain during ageing, by use of a semi-quantitative fluorescence in situ hybridization (FISH) method. In these experiments we have utilised the digital imaging capabilities of a cooled CCD camera system to store the fluorescence intensities of individual cells and to compare the data from each target (fos or jun) gene with that of a control (beta-actin) gene. In this way we have been able to obtain a relative quantitation of fos and jun mRNA levels. Purkinje cells were analysed in brain from Sprague-Dawley rats of 6, 13 and 23 months of age. Data obtained in this way demonstrated that the level of fos expression decreased significantly during ageing but, in contrast, that of jun increased between 6 and 13 months and thereafter remained constant. We subsequently carried out a further comparison of fos/jun ratios in purkinje cells in Wistar rats and also observed a highly significant fall in the ratio between 6 and 23 months. This change in the fos/jun ratio has important implications for the composition of the AP-1 transcription factor and for the expression of genes that it regulates.

Controlled ventilation enhances catheter stability during radiofrequency ablation

Variations in the amplitude of the atrial and ventricular depolarization waves of the intracardiac electrogram occur during different phases of respiration. Therefore, we tested whether controlled ventilation would reduce ablation attempts and increase the rate of success in patients undergoing radiofrequency ablation with general anesthesia. Thirty-eight children were divided into two groups: (1) controlled and (2) noncontrolled or cyclic ventilation. In the controlled ventilation group, the mapping electrogram was recorded during sustained inspiration, sustained expiration, and cyclic ventilation. Ablation was done in the phase of ventilation that had the least variability in atrial and ventricular amplitudes. Seventeen patients in the controlled ventilation group had tracings adequate for review. In eight patients, ablation was done during sustained inspiration with the percentage change of atrial and ventricular amplitudes (15% +/- 16% and 13% +/- 16%, respectively) being < that during sustained expiration (38% +/- 27%, P = 0.04 and 20% +/- 21%) or during cyclic ventilation (57% +/- 27%, P < 0.01 and 54% +/- 26%, P = 0.003). In nine patients, ablation was done during sustained expiration with the percentage change of atrial and ventricular amplitudes (5% +/- 5% and 5% +/- 2%) being less than that during sustained inspiration (21% +/- 14%, P = 0.01 and 11% +/- 6%, P = 0.01) or during cyclic ventilation (68% +/- 23%, P < 0.001 and 48 +/- 26%, P = 0.001). We achieved success with each patient in both groups, but the number of ablation attempts were less in the controlled ventilation group 1 (3 +/- 2), as compared to the cyclic ventilation group 2 (8 +/- 8; P < 0.02). We concluded that controlled ventilation reduced the number of ablation attempts and facilitated the ablation procedure.

Expression of retinol binding protein and transthyretin during early embryogenesis

Previous studies have shown that anterior lateral plate endoderm from stage 6 chicken embryos is necessary and sufficient to enable precardiac mesoderm to complete its cardiogenic program in vitro, culminating in a rhythmically contractile multicellular vesicle (Sugi and Lough [1994] Dev. Dyn. 200:155-162). To identify cardiogenic factors, we have begun to characterize proteins that are secreted by endoderm cell explants. Fluorography of proteins from endoderm-conditioned medium revealed 1-2 dozen bands, the most prominent of which migrated at approximately 17 and 25 kD. The bulk of the 17-kD band, which migrates near FGFs and subunits of the transforming growth factor-beta family, was identified by N-terminal sequencing as transthyretin (TTR). A component of the 25-kD band was identified by Western blotting as retinol binding protein (RBP). RT/PCR analysis revealed that mRNAs for both proteins are in the embryo as early as stage 3. In situ hybridization localized these mRNAs to the extraembryonic endoderm at stage 6, after which they were detected in endoderm overlying the embryo proper, including the developing heart. Later, RBP and TTR mRNA and protein were detected in cells associated with the developing heart. Western blotting of whole embryo proteins revealed the presence of RBP by stage 7, followed by sequential increases to stage 25; by contrast, content of RBP in isolated hearts peaked at stage 14, then declined. Immunohistochemistry revealed the presence of RBP protein in the extracellular matrix subjacent to lateral plate endoderm beginning at stage 8; upon formation of the definitive heart, intense staining was observed in the cardiac "jelly." By contrast TTR was intracellular, first detected as subtle deposits in stage 6 embryonic endoderm, which by stage 8 were prominent in the dorsally invaginated endoderm subjacent to the precardiac splanchnic mesoderm. At stages 11-14, TTR was detected only in myocardial cells. Such localization of RBP and TTR may indicate a role in the transport and distribution of retinol and thyroid hormone, respectively, from yolk to embryo prior to establishment of the circulatory system, and is suggestive of a subsequent role in heart development.

Disease surveillance in the ED: factors leading to the underreporting of gonorrhea

Emergency departments (EDs) are potentially important surveillance sites. This study assessed reporting completeness for gonorrhea by hospital and gender and explored reasons for underreporting. A retrospective review was conducted of ED charts from three hospitals for 2 months. Potential gonorrhea cases were identified by history, physical examination, testing, treatment, and diagnostic practices. Cases were divided into those tested only, those treated with or without testing, and those with positive tests. Reporting completeness was assessed for each. Of 936 cases included, 29.0% were tested without treatment and 71% received treatment. One third of treated patients were not tested, and none of these were reported. Two EDs reported cases themselves and reported 75.9% of confirmed cases. There were significant differences in testing and reporting between hospitals and genders. Underreporting of suspected and confirmed gonorrhea cases was common from these EDs. A major cause was physicians treating without testing for confirmation.

Combined BMP-2 and FGF-4, but neither factor alone, induces cardiogenesis in non-precardiac embryonic mesoderm

Previous work in this laboratory has shown that endoderm cells in the heart forming region (HFR endoderm) of the chicken embryo induce terminal cardiac differentiation in explanted precardiac mesoderm cells. Immunostaining patterns indicating that HFR endoderm cells express Drosophila decapentaplegic (dpp)-like antigens prompted a degenerate polymerase chain reaction (PCR) screen to identify cDNAs in the dpp subgroup of the transforming growth factor-beta (TGF-beta) family. Among 50 clones of PCR products that have been sequenced, over half have identity with bone morphogenetic protein-2 (BMP-2). No other TGF-beta cDNAs have been detected, suggesting that BMP-2 is the major dpp subgroup protein synthesized by HFR endoderm cells. However, BMP-2 protein did not promote survival of either precardiac or non-precardiac mesoderm cells in culture. Whereas FGF-4 supports cardiogenesis in precardiac mesoderm, it did not induce cardiogenesis in nonprecardiac mesoderm, although explant viability was maintained. In contrast to the isolated effects of these growth factors, treatment of non-precardiac mesoderm with combined BMP-2 and FGF-4 induced cardiogenesis in the majority of explants, as revealed by the formation of a rhythmically contractile multicellular vesicle that expresses sarcomeric alpha-actin. These findings suggest that BMP-2 and FGF-4 possess respective differentiative and proliferative activities, the combination of which specifies cells to the cardiac lineage.

Developmental expression of fibroblast growth factor receptor-1 (cek-1; flg) during heart development

Previous work in this laboratory has indicated that fibroblast growth factor-2 (FGF-2; bFGF) regulates the initial stages of avian heart development in paracrine and autocrine fashion (Parlow et al. [1991] Dev. Biol. 146:139-147; Sugi et al. [1993] Dev. Biol. 157:28-37). Because these findings inferred the presence of a functional receptor for fibroblast growth factor (FGFR), we have immunochemically assessed the appearance of FGFR-1 (cek-1; flg) during development. Using a peptide-generated antibody, Western blots of total embryonic proteins revealed that FGFR-1 was barely detectable at pre-heart stages, followed by sequential increases in relative abundance that peaked at stage 24, followed by a decline at days 7-14. Western blots of proteins from isolated embryonic hearts demonstrated a similar developmental pattern, except that FGFR-1 expression was not decreased at later stages. The presence of FGFR-1 mRNA was verified by reverse transcription/polymerase chain reaction (RT/PCR) amplification. Immunohistochemical examination revealed punctate deposits of FGFR-1 in the precardiac endoderm at stage 6, followed by detection in the endoderm, foregut, and pre-cardiac splanchnic mesoderm at stage 8 and in the newly formed myocardium at the heart tube stage (9/10). By stage 13, FGFR-1 staining was observed only in the myocardium, a pattern which persisted at least until stage 30 (day 7), after which only isolated hearts were examined. After stage 30, staining was diminished in the ventricle, but not in the atrium. Staining of cardiac endothelial cells was not observed at any stage. A functional role for FGFR-1 was indicated by experiments in which anti-FGFR-1, but not pre-absorbed antiserum, retarded proliferation and multilayering of cardiogenic cells in an in vitro model of cardiac morphogenesis.

Symmetry of cerebral blood flow and cognitive responses to hypoglycaemia in humans

A low blood glucose level is associated with impairment of higher cerebral function and an increase in cerebral blood flow. This study examined whether there are differences in the physiological responses to hypoglycaemia between the cerebral hemispheres. Eight healthy men participated in two hyperinsulinaemic glucose clamp studies: after 60 min at 4.5 mmol/l, blood glucose was either lowered to 2.0 mmol/l and "clamped" there for 60 min (hypoglycaemia) or continuously maintained at 4.5 mmol/l (euglycaemia). Cardiac output, middle cerebral artery velocity (transcranial Doppler) and cerebral blood flow (133-xenon inhalation) were measured during the studies. Neuropsychological tests were used to determine whether hypoglycaemia caused differential impairment of hemispheric cognitive function. Hypoglycaemia was associated with symmetrical impairment of cognitive function in both cerebral hemispheres and a rise in cardiac output (from 5.5 [0.2] to 8.7 [0.2] l.min-1, p < 0.0001, mean [standard error]), middle cerebral artery velocity (from 55 [2.6] to 64 [2.8] cm.s-1, p < 0.002), and global cerebral blood flow (from 56 [2.6] to 69 [2.9] ml.100 g-1.min-1, p < 0.005 compared to pre-insulin values). There were no differences in the blood flow response during hypoglycaemia between hemispheres and the increase in blood flow did not correlate with either the change in cardiac output or rise in plasma catecholamine levels. After 120 min of hyperinsulinaemic, euglycaemia, global cerebral blood flow rose significantly above baseline (from 58 [2.4] to 63 [2.2] ml.100 g-1.min-1, p < 0.05). In conclusion, using the techniques described, the physiological and cognitive responses of each cerebral hemisphere to hypoglycaemia were symmetrical.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional anesthesia of the eye and orbit

The principles and techniques of providing topical and regional anesthesia to the eye are presented in this article. Potential complications and their treatments are outlined, with special emphasis placed on the characteristics of the oculocardiac reflex.

Dystrophin or a "related protein" in Duchenne muscular dystrophy?

Previously we have shown low levels of dystrophin immunoreactivity in muscle from patients with DMD. According to the "frame-shift hypothesis" DMD muscle should not synthesize any dystrophin through to the C-terminus and it has been suggested that the protein detected is not dystrophin, but a related autosomal homologue. We have labelled serial sections of DMD muscle with specific monoclonal antibodies to the amino, rod and C-terminal domains of dystrophin and find labelling on the same individual fibres, allowing us to conclude that the protein detected is Xp21-encoded dystrophin. This has an impact on the interpretation of myoblast transfer experiments. The abundance (on blots) of "C-terminal dystrophin" appears lower than "rod dystrophin" in both BMD and DMD.

Staghorn calculi: analysis of treatment results between initial percutaneous nephrostolithotomy and extracorporeal shock wave lithotripsy monotherapy with reference to surface area

Treatment recommendations and results reported for the management of staghorn calculi are highly variable. In an attempt to provide a more objective means to compare treatment results for staghorn renal calculi, stone burden as measured by stone surface area was used. Stone surface area was determined by computer analysis. A total of 380 cases of staghorn calculi treated at the same institution was evaluated. Treatment consisted of initial percutaneous nephrostolithotomy with or without extracorporeal shock wave lithotripsy (ESWL*) in 298 cases and ESWL monotherapy in 82. When considered as a group, the overall stone-free rate for initial percutaneous nephrostolithotomy (mean surface area 1,378.3 mm.2) was 84.2% compared to 51.2% (p less than 0.0001) for ESWL monotherapy (mean surface area 693.4 mm.2). For staghorn calculi smaller than 500 mm.2 a stone-free rate of 94.4% was achieved in the percutaneous nephrostolithotomy with or without ESWL group compared to 63.2% for ESWL monotherapy (p = 0.0214). For calculi of 501 to 1,000 mm.2 the stone-free rates were 86% and 45.7%, respectively (p less than 0.0001). When stone surface area exceeded 1,000 mm.2 the stone-free rate for percutaneous nephrostolithotomy with or without ESWL was 82.4% but it was only 22.2% for ESWL monotherapy (p = 0.0002). Overall, when adjusted for stone surface area the odds of being stone-free were more than 8 times higher for initial percutaneous nephrostolithotomy versus ESWL monotherapy (odds ratio = 8.36, p less than 0.0001). While percutaneous nephrostolithotomy with or without ESWL appears to be the procedure of choice for most staghorn stones, ESWL monotherapy may have a role for some stones smaller than 500 mm.2. In 12 such cases associated with a nondilated renal collecting system (mean surface area 380.5 mm.2) a stone-free rate of 91.7% was achieved. The number of procedures required to complete therapy was higher in the initial percutaneous nephrostolithotomy group (2.8 versus 2.1, p less than 0.0001). Although complications were more common in the ESWL monotherapy group (manifested as obstruction in 30.5%), bleeding requiring blood transfusion was more frequent in the initial percutaneous nephrostolithotomy group (9.4%).

Geographic variation in lumbar diskectomy: a protocol for evaluation

In 1989 the Maryland Hospital Association (MHA) began developing a protocol related to lumbar diskectomy, a procedure with widely reported geographic variation in its use. The MHA's Laminectomy Advisory Committee drafted three criteria for performance of lumbar diskectomy and also developed a data-collection instrument with which the eight hospitals participating in a pilot study could abstract the necessary data from medical records. Both individual hospital and aggregate results showed wide variation in compliance with the criteria. These findings suggest research and development activities such as refinement of the data-collection instrument, use of the protocol for bench-marking, further investigation of clinical and other determinants of rate variation, and study of the effect of new diagnostic technology on utilization rates for this procedure.

Characterization of antigenic sites of human prostatic acid phosphatase

Human prostatic acid phosphatase [PAP] is antigenically uniquely different from acid phosphatases of other tissue origins. Nevertheless, a small degree of antigenic cross-reactivity between PAP and other lysosomal acid phosphatase(s) [LAP] has been suspected. In order to resolve this question, we have adopted two approaches: one involving structural studies by peptide mapping, and the other involving topological mapping through the use of uniquely defined antibodies. Purified PAP was dissociated into subunits and was further cleaved by chemical and enzymological methods. The limited digestion of PAP by submaxillary protease yielded three fragments [Sp-1, 2, and 3]. One of the fragments, Sp-3 [Mr = 11,000-12,000], was shown to regain catalytic activity after interaction with anti-PAP antibodies. This along with other data suggested that the active site is localized in the Sp-3 fragment. These submaxillary protease fragments were also used in the antigenic studies. For the detailed antigenic mapping studies, we prepared 12 monoclonal anti-PAP antibodies. These monoclonal anti-PAP antibodies exhibited a remarkably specific binding to PAP, particularly to the Sp-1 fragment, without binding to other acid phosphatase preparations. We also prepared lysosomal acid phosphatase [LAP] and raised anti-LAP antibodies in rabbits. The anti-LAP antibodies were fractionated into subpopulations by the preparative isoelectric focusing method. Three anti-LAP antibody subpopulations [pI 5.2, 6.9, and 7.5] exhibited specific binding to LAP. However, two anti-LAP subpopulations [pI 5.3 and and 6.8] showed binding to the Sp-3 fragment, an active site fragment of PAP. Thus, the PAP molecule seems to consist of three domains, namely, Sp-1, Sp-3, and Sp-2. Sp-3, which is the active site domain, is an antigenically cross-reactive region. The Sp-1 domain represents an antigenically unique region of PAP, whereas none of the antibodies studied thus far bind to the Sp-2 fragment.

A disposable corneal trephine

Postoperative astigmatism might be reduced in penetrating keratoplasty if surgeons could cut a straight-sided round hole in the recipient cornea and place in that hole a round donor button also having straight sides. We present a disposable trephine which assists in cutting a perfect graft by supporting the cornea with a suction ring while an uncommonly sharp, round blade traverses the tissue.