Toxigenic Corynebacterium ulcerans infection in a veterinary student in London, United Kingdom, May 2010

We report on a case of toxigenic Corynebacterium ulcerans infection in a fully immunised veterinary student, investigated in London, United Kingdom, in May 2010. There was no ongoing transmission in human contacts. Possible animal sources were identified.

Toxigenic Corynebacterium ulcerans infection in a veterinary student in London, United Kingdom, May 2010

We report on a case of toxigenic Corynebacterium ulcerans infection in a fully immunised veterinary student, investigated in London, United Kingdom, in May 2010. There was no ongoing transmission in human contacts. Possible animal sources were identified.

Assessment of total thrombus load in symptomatic patients with venous thromboembolism

Pulmonary embolism (PE) and Deep vein thrombosis (DVT) are separate but related aspects of the same dynamic process termed as venous thrombembolism (VTE). The existing Asian literature has shown a wide variation in the prevalence of VTE, with very limited data from the Indian subcontinent. Between January 2001 and July 2004, 1,552 patients with clinically suspected lower limb DVT underwent a combined ascending radionuclide venogram and lung perfusion scan for assessment of the total thrombus burden. Of 744 patients with radionuclide venography proven DVT, 294 (40%) had a high probability lung scan. Nearly half of these patients were asymptomatic for pulmonary embolism. The high prevalence of PE in patients with DVT suggests the need for evaluation of thrombus load in the venous as well as pulmonary circulation. A combination radionuclide ascending venography with lung perfusion scan is a useful and reliable single test for this purpose.

Effect of aspirin on phase gradient of 2F1-F2 distortion product otoacoustic emissions

It is well known that aspirin consumption temporarily reduces overall otoacoustic emission (OAE) amplitude in humans. However, little is known about changes in the separate components of distortion product otoacoustic emissions (DPOAE), which may be distinguished by examining phase gradients. The effects of aspirin on the phase gradient of the DPOAE 2F1-F2 obtained with fixed frequency ratio sweeps were studied longitudinally in a group of twelve subjects in whom a temporary hearing loss was induced by aspirin consumption. DPOAE were recorded daily for two days pre-aspirin consumption, during the three days of aspirin consumption and two days afterwards. DP-grams were recorded over a restricted frequency range centered on 2,3,4 and 6 kHz with the following stimulus levels: L1/L2 of 60/50-80/70 in 10-dB steps. The effects of aspirin on the phase gradients varied between the subjects and across frequency: the general trend was that the phase gradient became steeper across successive sessions for the higher frequencies, while no significant effect was found at the lower frequencies. These results suggest that aspirin may have more persistent effects on cochlear function than are disclosed by measurements of hearing threshold level or DPOAE amplitude. Particularly, DPOAE phase gradient appears to be increased by aspirin consumption and has not recovered two days after cessation of aspirin intake, despite almost complete recovery of DPOAE amplitude and hearing threshold levels. These findings may suggest differential effects on the distortion and reflection mechanisms considered to underlie DPOAE generation.

Percutaneous transluminal alcohol septal myocardial ablation after aortic valve replacement

When left ventricular outflow tract obstruction develops after aortic valve replacement, few treatment choices have been available until now. We present a patient with prior aortic valve replacement who developed left ventricle outflow tract obstruction that was successfully treated with a percutaneous transcoronary myocardial septal alcohol ablation. This technique is a useful tool for the treatment of obstructive hypertrophic cardiomyopathy, especially in those patients with prior heart surgery.

Herbal remedy poisoning presenting with acute abdomen and raised urine porphyrins

We describe a case of lead poisoning due to herbal remedies, presenting with an acute abdomen, raised porphyrins and increased liver enzyme activities. We suggest that lead poisoning should be considered in the differential diagnosis of the 'acute abdomen', and that the presence of liver dysfunction points to the possibility of Asian herbal remedies as the source of the lead poisoning.

Static input-output non-linearity as the source of non-linear effects in maximum length sequence click-evoked OAEs

The application of the maximum length sequence (MLS) technique to the recording of click-evoked otoacoustic emissions (CEOAEs) allows for a reduction in test time by one to two orders of magnitude. This is because the technique permits the use of extremely high click rates, as inter-click intervals are not constrained to be greater than the duration of the response. However, increasing the click rate also causes a progressive reduction in amplitude, or 'suppression', of the CEOAE. The origin of this suppression is unclear, with diverse suggestions in the literature as to its nature and mechanism. This paper presents a simple model of the well-known compressive non-linearity of the CEOAE level function, based on a static amplitude non-linearity within each of a number of narrowband frequency channels. The response of the model to MLS stimulation demonstrates suppression broadly of the form and magnitude previously reported in experimental studies. Furthermore, the model exhibits the generation of additional non-linear components that have been speculated on in connection with CEOAE recordings using the MLS technique. It is concluded that the MLS suppression phenomenon is derived largely, if not entirely, from the static non-linearity of the CEOAE level function. The approach to modelling the phenomenon as described here also bears promise for understanding various aspects of non-linearity in MLS-based CEOAE recordings.

Regulation of the bovine kidney microsomal chloride channel p64 by p59fyn, a Src family tyrosine kinase

p64 is a chloride channel of intracellular membranes which is present in regulated secretory vesicles. Mechanisms by which the p64 channel could be regulated are largely unknown. p59(fyn) is a non-receptor tyrosine kinase of the Src family that has been implicated in a variety of intracellular signaling events. The N-terminal portion of p64 has several potential binding sites for Src family SH2 domains. In this paper, we demonstrate that p64 becomes tyrosine phosphorylated when co-expressed with p59(fyn) in HeLa cells. We show that co-expression of p64 with p59(fyn) renders p64 a ligand for the SH2 domain of p59(fyn) and this SH2 binding is eliminated by treating p64 with alkaline phosphatase. Using site-directed mutagenesis, we find that tyrosine 33 in the p64 sequence is necessary for SH2 binding. We also characterized p64-p59(fyn) interactions using native material from bovine kidney. We found that a small fraction of native kidney p64 can bind Fyn SH2 in vitro. Immunoprecipitation of p64 from solubilized kidney membranes yields a kinase activity with the same mobility by SDS-polyacrylamide gel electrophoresis as authentic bovine p59(fyn). Finally, we demonstrate that co-expression of p64 and p59(fyn) in HeLa cells results in enhanced p64-associated chloride channel activity.

Nonlinear temporal interactions in click-evoked otoacoustic emissions. I. Assumed model and polarity-symmetry

Click-evoked otoacoustic emissions (CEOAEs) are reduced in amplitude by the presentation of 'suppressor' clicks that either closely lead or follow the stimulus ('test') clicks. This suppression of the response represents nonlinear temporal interactions between the test and suppressor clicks and/or the CEOAEs they evoke. There are some discrepancies amongst previous reports of the phenomenon, and the underlying mechanisms are not understood. In particular, it is unclear whether the suppression reported simply reflects the compressive nonlinearity of the CEOAE input-output (I-O) function. This paper presents a simple model of the nonlinear interactions between CEOAEs evoked by two closely-spaced clicks. The model shows that suppression as reported may be entirely derived from CEOAE I-O nonlinearity, in combination with the extended duration of the cochlear responses to click stimuli. It is also shown experimentally that suppression is insensitive to the polarities of test and suppressor clicks, which is consistent with the model based on I-O nonlinearity. A companion paper (Kapadia and Lutman, Hear. Res. 146 (2000)) presents experimental findings from a detailed parametric study of nonlinear temporal interactions in CEOAEs in human subjects with normal hearing. The findings are compared with the pattern of results generated by the above model, in order to assess the role of I-O nonlinearity in these nonlinear interactions.

Nonlinear temporal interactions in click-evoked otoacoustic emissions. II. Experimental data

Click-evoked otoacoustic emissions (CEOAEs) are reduced in amplitude by the presentation of 'suppressor' clicks that either closely lead or follow the stimulus ('test') clicks. A model described in a companion paper (Kapadia and Lutman, Hear. Res. 146 (2000) 89-100) shows that such nonlinear temporal interactions, as previously reported, may be explained in terms of the compressive non-linearity of the CEOAE input-output (I-O) function. This paper presents the results of a detailed parametric investigation into such nonlinear interactions, studied in 12 normal adult ears over a wide range of test and suppressor click levels and inter-click intervals. The results differ from those generated by the model in a number of respects. Principally, maximum suppression is generally obtained for suppressors presented in advance of test clicks, rather than co-incident with the test clicks. The amount of advance depends systematically on the two click levels. The measured suppression can also exceed the theoretical maximum allowed by the model. It is concluded that the nonlinear temporal interactions measured do not simply reflect CEOAE I-O function non-linearity. They may, instead, arise from disturbance of the generator elements from their resting state prior to generation of the CEOAE. These results may also have general implications relating to cochlear responses to transient stimuli and indicate the potential of CEOAEs in probing aspects of cochlear mechanics.

Reduced àudiogram ripple' in normally-hearing subjects with weak otoacoustic emissions

Correspondence between spectral patterns in otoacoustic emissions (OAE) and the fine structure of the pure-tone audiogram has often been noted, but the link is by no means clearly understood nor complete in all subjects. This paper presents part of a broader study focusing on individuals with normal hearing but anomalously weak OAEs, the primary purpose of which was to determine the reasons for the weak OAEs. Subjects were selected from an exhaustive search of some 400 ears of highly co-operative adults, and comprised a test group of subjects with normal hearing thresholds but weak OAEs, and a control group of normals from the same sample. Reported here are data on audiogram fine structure measured in the two groups of subjects. The basic finding is that the subjects with weak OAEs also exhibited significantly less audiogram fine structure than the controls, as evaluated by analysing the periodicity in the respective threshold curves as well as by identifying and quantifying individual peaks in the curves. These findings first provide further evidence of an underlying link between the fine structure of the audiogram and OAEs, as proposed by Kemp in his original work. Second, assuming that the degree of fine structure would be largely unaffected by minor middle ear alterations, our findings suggest that predominantly cochlear rather than middle ear factors are responsible for the low levels of OAEs in the normal subjects of our test group. Finally, the results presented suggest that, like OAEs, audiogram fine structure measurements provide information on the auditory system that is not available in the conventional pure-tone audiogram.

Targeted expression of calcitonin gene-related peptide to osteoblasts increases bone density in mice

The neuropeptide calcitonin gene-related peptide (CGRP) is concentrated in fine sensory nerve endings innervating all tissues, including bone. CGRP inhibits osteoclasts, stimulates insulin-like growth factor I and inhibits tumor necrosis factor alpha production by osteoblasts in vitro. To investigate the role of CGRP in bone in vivo, mice were engineered to express CGRP in osteoblasts by placing the human CGRP gene under the control of the rat osteocalcin promoter (Ost-CGRP tg+ mice). Calvaria cultures from transgene positive (tg+), but not tg- mice, produced bioactive CGRP. Trabecular bone density and bone volume, determined by peripheral quantitative computed tomography and bone histomorphometry, respectively, were higher in tg+ than tg- littermates. This increase in bone volume was associated with an increased bone formation rate. Trabecular bone density decreased in tg+ mice as a result of ovariectomy, but remained higher than in sham tg- mice. Targeting CGRP to osteoblasts appears to favor the establishment of a higher trabecular bone mass in mice.

Prognosis of patients with vascular disease after clinical evaluation and dobutamine stress echocardiography

BACKGROUND

Coronary disease is an important cause of long-term morbidity in patients needing major vascular surgery. We sought to assess the efficacy of preoperative clinical evaluation and the detection of inducible ischemia for prediction of immediate and long-term cardiac outcomes of patients undergoing vascular surgery.

METHODS

In 233 patients undergoing vascular procedures, we assessed risk clinically on the basis of Eagle's criteria. Dobutamine echocardiography was performed with a standard protocol and results were classified as showing ischemia, scar, or a normal response. Patients were observed perioperatively, and late follow-up (28 +/- 13 months) was completed in all surgical survivors. A composite end point of cardiac death, myocardial infarction, and unstable and progressive angina requiring late revascularization was used to judge event-free survival.

RESULTS

Of 233 patients undergoing preoperative dobutamine echocardiography, 39 (17%) had inducible ischemia and 36 (15%) had scar. Perioperative events occurred in 8 patients (3%). None of the patients with ischemia had perioperative events, reflecting the effect of revascularization in 9 patients. Late events occurred in 36 patients; ischemia on preoperative stress testing was a predictor of these events even after adjusting for clinical variables and left ventricular dysfunction (relative risk = 3.3; 95% confidence interval 1.6 to 6.8; P =.001). The association of ischemia with clinical predictors was associated with incrementally worse outcome.

CONCLUSION

In addition to perioperative assessment, the combined use of clinical and dobutamine echocardiographic evaluation may stratify the risk of late cardiac events.

Progressive septal and palatal perforation secondary to intranasal cocaine abuse

Septal perforation from intranasal cocaine abuse is well recognised. We present a case of progressive septal as well as palatal perforation. Progression from septal perforation to palatal perforation occurred after cessation of intranasal cocaine abuse. This patient had a weakly positive cytoplasmic antineutrophilic cytoplasmic antibody (C-ANCA) but no histologic evidence of Wegener's Granulomatosis. The differential diagnosis for septal and palatal perforation is reviewed. This case represents the fifth reported case of palatal perforation secondary to cocaine abuse in the literature, and the second associated with positive C-ANCA.

The role of cytokines in the failing human heart

Despite repeated attempts to develop a unifying hypothesis that explains the clinical syndrome of heart failure, no single conceptual paradigm has withstood the test of time. In this regard, recent studies have shown that a class of biologically active molecules, generically referred to as cytokines, are overexposed in heart failure. This article will review recent clinical and experimental material that suggest proinflammatory (stress activated) cytokines such as tumor necrosis factor-alpha (TFN-alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6) may play a role in the pathogenesis of congestive heart failure. The scope of this article includes an overview of the biology of cytokines in the heart, as well as review of the clinical studies that have documented elevated levels of cytokines and cytokine receptors in patients with heart failure.