Fat-induced membrane cholesterol accrual provokes cortical filamentous actin destabilisation and glucose transport dysfunction in skeletal muscle

AIMS/HYPOTHESIS

Diminished cortical filamentous actin (F-actin) has been implicated in skeletal muscle insulin resistance, yet the mechanism(s) is unknown. Here we tested the hypothesis that changes in membrane cholesterol could be a causative factor, as organised F-actin structure emanates from cholesterol-enriched raft microdomains at the plasma membrane.

METHODS

Skeletal muscle samples from high-fat-fed animals and insulin-sensitive and insulin-resistant human participants were evaluated. The study also used L6 myotubes to directly determine the impact of fatty acids (FAs) on membrane/cytoskeletal variables and insulin action.

RESULTS

High-fat-fed insulin-resistant animals displayed elevated levels of membrane cholesterol and reduced F-actin structure compared with normal chow-fed animals. Moreover, human muscle biopsies revealed an inverse correlation between membrane cholesterol and whole-body glucose disposal. Palmitate-induced insulin-resistant myotubes displayed membrane cholesterol accrual and F-actin loss. Cholesterol lowering protected against the palmitate-induced defects, whereas characteristically measured defects in insulin signalling were not corrected. Conversely, cholesterol loading of L6 myotube membranes provoked a palmitate-like cytoskeletal/GLUT4 derangement. Mechanistically, we observed a palmitate-induced increase in O-linked glycosylation, an end-product of the hexosamine biosynthesis pathway (HBP). Consistent with HBP activity affecting the transcription of various genes, we observed an increase in Hmgcr, a gene that encodes 3-hydroxy-3-methyl-glutaryl coenzyme A reductase, the rate-limiting enzyme in cholesterol synthesis. In line with increased HBP activity transcriptionally provoking a membrane cholesterol-based insulin-resistant state, HBP inhibition attenuated Hmgcr expression and prevented membrane cholesterol accrual, F-actin loss and GLUT4/glucose transport dysfunction.

CONCLUSIONS/INTERPRETATION

Our results suggest a novel cholesterolgenic-based mechanism of FA-induced membrane/cytoskeletal disorder and insulin resistance.

Using electronic medical records to enable large-scale studies in psychiatry: treatment resistant depression as a model

BACKGROUND

Electronic medical records (EMR) provide a unique opportunity for efficient, large-scale clinical investigation in psychiatry. However, such studies will require development of tools to define treatment outcome.

METHOD

Natural language processing (NLP) was applied to classify notes from 127 504 patients with a billing diagnosis of major depressive disorder, drawn from out-patient psychiatry practices affiliated with multiple, large New England hospitals. Classifications were compared with results using billing data (ICD-9 codes) alone and to a clinical gold standard based on chart review by a panel of senior clinicians. These cross-sectional classifications were then used to define longitudinal treatment outcomes, which were compared with a clinician-rated gold standard.

RESULTS

Models incorporating NLP were superior to those relying on billing data alone for classifying current mood state (area under receiver operating characteristic curve of 0.85-0.88 v. 0.54-0.55). When these cross-sectional visits were integrated to define longitudinal outcomes and incorporate treatment data, 15% of the cohort remitted with a single antidepressant treatment, while 13% were identified as failing to remit despite at least two antidepressant trials. Non-remitting patients were more likely to be non-Caucasian (p<0.001).

CONCLUSIONS

The application of bioinformatics tools such as NLP should enable accurate and efficient determination of longitudinal outcomes, enabling existing EMR data to be applied to clinical research, including biomarker investigations. Continued development will be required to better address moderators of outcome such as adherence and co-morbidity.

Therapeutic aerosol bioengineering of targeted, inhalable microparticle formulations to treat Mycobacterium tuberculosis (MTb)

Therapeutic aerosol bioengineering (TAB) of Mycobacterium tuberculosis (MTb) therapies using inhalable microparticles offers a unique opportunity to target drugs to the site of infection in the alveolar macrophages, thereby increasing dosing in the lungs and limiting systemic exposure to often toxic drugs. Previous work by us used sophisticated, high content analysis to design the optimal poly(lactide-co-glycolic) acid (PLGA) microparticle for delivery of drugs to alveolar macrophages. Herein, we applied this technology to three different anti-MTb drugs. These formulations were then tested for encapsulation efficiency, drug-release, in vitro killing against MTb and aerosol performance. Methods for encapsulating each of the drugs in the PLGA microparticles were successfully developed and found to be capable of controlling the release of the drug for up to 4 days. The efficacy of each of the encapsulated anti-MTb drugs was maintained and in some cases enhanced post-encapsulation. A method of processing these drug-loaded microparticles for inhalation using standard dry powder inhaler devices was successfully developed that enabled a very high respirable dose of the drug to be delivered from a simple dry powder inhaler device. Overall, TAB offers unique opportunities to more effectively treat MTb with many potential clinical and economic benefits resulting.

Guidelines for autopsy investigation of sudden cardiac death

Although sudden cardiac death is one of the most important mode of death in Western Countries, pathologists and public health physicians have not given this problem the attention it deserves. New methods of preventing potentially fatal arrhythmias have been developed and the accurate diagnosis of the causes of sudden cardiac death is now of particular importance. Pathologists are responsible for determining the precise cause of sudden death but there is considerable variation in the way in which they approach this increasingly complex task. The Association for European Cardiovascular Pathology developed these Guidelines, which represent the minimum standard that is required in the routine autopsy practice for the adequate assessment of sudden cardiac death, including not only a protocol for heart examination and histological sampling, but also for toxicology and molecular investigation. Our recommendations apply to University Medical Centres, Regional and District Hospitals and all types of Forensic Medicine Institutes. If a uniform method of investigation is adopted throughout the European Union, this will lead to improvements in standards of practice, allow meaningful comparisons between different communities and regions and, most importantly, permit future trends in the patterns of disease causing sudden death to be monitored.

Atherogenesis: the role of inflammation and infection

Atherosclerosis is no longer considered a disorder of lipid accumulation, but a disease process characterized by the dynamic interaction between endothelial dysfunction, subendothelial inflammation and the 'wound healing response' of the vascular smooth muscle cells. Prospective epidemiological studies have unequivocally demonstrated increased vascular risk in individuals with elevated levels of (i) cytokines such as interleukin-6 and tumour necrosis factor-alpha, (ii) cell adhesion molecules such as intercellular adhesion molecule-1 and P-selectin, and (iii) acute-phase proteins such as C-reactive protein, fibrinogen and serum amyloid A. Furthermore, evidence from clinical trials have demonstrated that risk reduction achieved with anti-inflammatory agents such as statins is significantly greater in patients with evidence of inflammation. A number of risk factors for atherogenesis, including infectious agents, have been shown to exert their influence via inflammatory mechanisms. However, despite compelling experimental evidence, clinical studies looking at the role of infection in atherogenesis have lacked consistency. The clinical product of this dynamic process is variable and unpredictable between individuals, even those with apparently similar risk profiles.

Histological assessment of 526 symptomatic carotid plaques in relation to the nature and timing of ischemic symptoms: the Oxford plaque study

BACKGROUND

Atherosclerotic plaque at the carotid bifurcation is often associated with transient ischemic attack (TIA) and ischemic stroke, but the mechanisms are not completely understood. Previous histological studies have been too small or insufficiently detailed to reliably determine the temporal course of features of plaque instability or to stratify analyses by the nature of presenting symptoms.

METHODS AND RESULTS

We performed the largest-ever histological study of symptomatic carotid plaques from consecutive patients (n=526) undergoing endarterectomy and related detailed reproducible histological assessments to the nature and timing of presenting symptoms. There was a high prevalence of many features of coronary-type plaque instability. Dense plaque inflammation (especially infiltration with macrophages) was the feature most strongly associated with both cap rupture (odds ratio 3.39, 95% confidence interval 2.31 to 4.98, P<0.001) and time since stroke (P=0.001). Strong negative associations with time since stroke were also seen for cap rupture (P=0.02), overall plaque inflammation (P=0.003), and "unstable plaque" (P=0.001). Although plaques removed < or =60 days after the most recent event were more unstable after a stroke than after a TIA, the instability persisted after a TIA, and plaques removed >180 days after most recent event were less unstable after a stroke than after a TIA (plaque inflammation: < or =60 days, odds ratio 2.33 [95% confidence interval 0.76 to 7.19]; >180 days, 0.36 [0.16 to 0.84]; P=0.008; unstable plaque: odds ratio 3.27 [95% confidence interval 0.93 to 11.50] versus 0.74 [0.33 to 1.69], P=0.05).

CONCLUSIONS

Pathology of recently symptomatic carotid plaques is similar to that of culprit coronary plaques, with strong correlations between macrophage infiltration and plaque instability. The tendency for plaque inflammation and overall instability to persist with time after a TIA but to decrease with time after a stroke suggests that the nature of the underlying pathology may differ.

Histological correlates of carotid plaque surface morphology on lumen contrast imaging

BACKGROUND

Carotid angiographic plaque surface morphology is a powerful risk factor for stroke and systemic vascular risk. However, the underlying pathology is unclear, and a better understanding is required both to evaluate other forms of carotid imaging and to develop new treatments. Previous studies comparing angiographic plaque surface morphology with pathology have been small and unblinded, and the vast majority assessed only the crude macroscopic appearance of the plaque. We performed the first large study comparing angiographic surface morphology with detailed histology.

METHODS AND RESULTS

Carotid plaque surface morphology was classified as ulcerated, irregular, or smooth on 128 conventional selective carotid artery angiograms from consecutive patients undergoing endarterectomy for severe symptomatic stenosis. Blinded angiographic assessments were compared with 10 histological features recorded on detailed microscopy of the plaque using reproducible semiquantitative scales. Angiographic ulceration was associated with plaque rupture (P=0.001), intraplaque hemorrhage (P=0.001), large lipid core (P=0.005), less fibrous tissue (P=0.003), and increased instability overall (P=0.001). For example, angiographically ulcerated plaques were much more likely than smooth plaques to be ruptured (OR=15.4, 95% CI=2.7 to 87.3, P<0.001), show a large lipid core (OR=26.7, 95% CI=2.6 to 270, P<0.001) or a large hemorrhage (OR=17.0, 95% CI=2.0 to 147, P=0.02). The equivalent odds ratios for angiographically irregular versus smooth plaque were 6.3 (1.3 to 31, P=0.02), 6.7 (1.5 to 30, P=0.008), and 9.2 (1.1 to 77, P=0.02), respectively.

CONCLUSIONS

In contrast to previous studies based on macroscopic assessment, we found very strong associations between detailed histology and carotid angiographic plaque surface morphology. Plaque surface morphology on carotid angiography is a highly sensitive marker of plaque instability. Studies of the predictive value of MR- and CT-based lumen contrast plaque surface imaging are required.

Reproducibility of histological assessment of carotid plaque: implications for studies of carotid imaging

BACKGROUND

Thromboembolism from carotid plaque is an important cause of stroke. Identification of unstable plaque would therefore be clinically useful. Unfortunately, studies of carotid plaque imaging have shown poor agreement with histology. However, this may be due to inconsistent methods and the variability of assessments of carotid plaque histology, rather than inadequate imaging.

METHODS

We assessed the reproducibility of histological assessment in 60 plaques, and section-to-section variability along the length of 26 plaques.

RESULTS

Kappa values ranged from 0.35 to 0.89 and from 0.44 to 0.68, respectively, for intra- and inter-observer reproducibility. There was considerable section-to-section variability within plaques.

CONCLUSIONS

The accuracy of imaging of carotid plaque morphology will be underestimated unless variability in the histology assessment is taken into account.

Primary venous dissecting aneurysm arising during pregnancy: a case report and review of the literature

This report describes a case of venous dissecting aneurysm presenting as a popliteal mass, in a 33 year old woman. A 1 x 1 x 0.5 cm lump developed early in the course of a second pregnancy. Primary venous aneurysms are rare vascular abnormalities that can affect either the superficial or deep veins, and have been described throughout the venous system. Most commonly found in the neck and central thoracic veins, they have also been found in visceral veins and extremities. There is a tendency for vascular disturbances to occur during pregnancy. The haemodynamic changes and hormonal milieu may be the cause of vascular alterations, which can lead to new aneurysm formation, or weakening of pre-existing aneurysms. This is the first reported case of a dissecting venous aneurysm, and has the added interest that it occurred during pregnancy.

Primary venous dissecting aneurysm arising during pregnancy: a case report and review of the literature

This report describes a case of venous dissecting aneurysm presenting as a popliteal mass, in a 33 year old woman. A 1 x 1 x 0.5 cm lump developed early in the course of a second pregnancy. Primary venous aneurysms are rare vascular abnormalities that can affect either the superficial or deep veins, and have been described throughout the venous system. Most commonly found in the neck and central thoracic veins, they have also been found in visceral veins and extremities. There is a tendency for vascular disturbances to occur during pregnancy. The haemodynamic changes and hormonal milieu may be the cause of vascular alterations, which can lead to new aneurysm formation, or weakening of pre-existing aneurysms. This is the first reported case of a dissecting venous aneurysm, and has the added interest that it occurred during pregnancy.

An initiative to reform senior house officer training in histopathology

Senior house officer schools in histopathology have been established in Leeds, Leicester and Southampton, each training six new recruits each year. Nine hours of protected teaching time is provided each week giving a ratio of apprenticeship learning to formal teaching of 3:1. Evaluations have been very positive. Much of this success is attributed to careful planning and adequate funding. This may be a useful model for other specialties to follow.

p53, DCC and thymidylate synthase as predictors of survival after resection of hepatic metastases from colorectal cancer

BACKGROUND

Hepatic metastasis from colorectal cancer is a common problem. Hepatic resection offers the only chance of cure. Prognosis of patients following hepatic resection is currently based on clinicopathological factors (of both the primary cancer and the hepatic metastasis), which do not accurately predict the subsequent behaviour of the tumour. The aim of this study was to evaluate three molecular genetic markers - p53, DCC (deleted in colonic cancer) and thymidylate synthase - in both the primary colorectal tumour and the resected hepatic metastases, and to determine their correlation, if any, with survival in patients with resected hepatic metastases from colorectal cancer.

METHODS

Sixty-three patients with hepatic metastases and 40 corresponding colorectal primary tumours were studied using immunohistochemical staining for p53, DCC and thymidylate synthase, as well as p53 gene mutations using polymerase chain reaction-single-stranded conformational polymorphism (PCR-SSCP) analysis. The results were correlated with survival.

RESULTS

There was no correlation between p53, DCC or thymidylate synthase immunohistochemical staining, or between p53 PCR-SSCP analysis, and survival for either hepatic metastases or the colorectal primary tumour.

CONCLUSION

Prediction of prognosis in patients having resection of hepatic metastases from colorectal cancer continues to be problematic. Other genetic markers or combination of markers need to be evaluated.

Localization of 3-nitrotyrosine to rheumatoid and normal synovium

OBJECTIVE

To determine the localization of 3-nitrotyrosine (3-NT), a footprint marker of peroxynitrite (ONOO-) and other reactive nitrogen species, to the inflamed human synovium and to compare this with normal synovial and nonsynovial tissue of human and animal origin.

METHODS

Monoclonal and polyclonal antibodies were used to investigate for 3-NT, inducible nitric oxide synthase (iNOS), macrophage marker CD68, and the vascular smooth muscle marker alpha-actin by avidin-biotin immunocytochemistry.

RESULTS

In the inflamed synovium, 3-NT was found in the vascular smooth muscle and macrophages. In normal human synovium, 3-NT was present in the vascular smooth muscle and some lining cells and was not associated with immunoreactivity for iNOS. Similarly, 3-NT could be demonstrated in the vascular smooth muscle cells of normal rats and iNOS knockout mice. It was not present in the vascular smooth muscle of healthy, nonsynovial tissue.

CONCLUSION

The synovial vasculature in histologically normal human and naive rodent synovium was alone among the normal tissues studied in exhibiting iNOS-independent immunoreactivity for 3-NT. These findings suggest a physiologic role for ONOO- in normal synovial vascular function.

Increased numbers of caveolae in retinal endothelium and pericytes in hypertensive diabetic rats

PURPOSE

Long-term clinical studies have now shown that tight control of blood pressure in type 2 diabetes reduces the risk of diabetes-related death and common diabetic complications, including diabetic retinopathy. However, the mechanisms by which hypertension enhances diabetic microvascular disease, especially diabetic retinopathy, are poorly understood. We developed an experimental model of hypertension in diabetic rats and studied the early ultrastructural changes in retinal capillaries under these conditions.

METHODS

Hypertension was induced in diabetic BioBreeding (BB) rats by unilateral nephrectomy, weekly subcutaneous mineralocorticoid and 0.9% oral saline. Serial blood pressures and ultrastructural features of retinal capillaries were recorded in four groups: normotensive Wistar rats, normotensive diabetic rats, hypertensive Wistar rats and hypertensive diabetic rats.

RESULTS

A significant and sustained increase in systolic blood pressure occurred in both groups of nephrectomised rats. There was a significant increase in the number of caveolae (i) in both pericytes and endothelial cells in animals with hypertension and diabetes together compared with all other groups and (ii) in pericytes in animals with diabetes alone. The number of direct contacts between pericytes and endothelial cells was reduced in diabetic and hypertensive diabetic animals. Hypertension and diabetes had an interactive effect in producing retinal capillary basement membrane thickening.

CONCLUSIONS

In the BB rat hypertension and diabetes have an interactive effect in increasing the number of caveolae in both endothelial cells and pericytes. We speculate that this may be a reflection of changes in calcium and nitric oxide metabolism in these animals.

Telokin expression is restricted to smooth muscle tissues during mouse development

Telokin is a 17-kDa protein with an amino acid sequence that is identical to the COOH terminus of the 130-kDa myosin light chain kinase (MLCK). Telokin mRNA is transcribed from a second promoter, located within an intron, in the 3' region of the MLCK gene. In the current study, we show by in situ mRNA hybridization that telokin mRNA is restricted to the smooth muscle cell layers within adult smooth muscle tissues. In situ mRNA analysis of mouse embryos also revealed that telokin expression is restricted to smooth muscle tissues during embryonic development. Telokin mRNA expression was first detected in mouse gut at embryonic day 11.5; no telokin expression was detected in embryonic cardiac or skeletal muscle. Expression of telokin was also found to be regulated during postnatal development of the male and female reproductive tracts. In both uterus and vas deferens, telokin protein expression greatly increased between days 7 and 14 of postnatal development. The increase in telokin expression correlated with an increase in the expression of several other smooth muscle-restricted proteins, including smooth muscle myosin and alpha-actin.

Manganese induces neurite outgrowth in PC12 cells via upregulation of alpha(v) integrins

Previous studies have demonstrated that the divalent cation manganese (Mn) causes PC12 cells to form neurites in the absence of NGF. Since divalent cations modulate the binding affinity and specificity of integrins, and integrin function affects neurite outgrowth, we tested the hypothesis that Mn induces neurite outgrowth through an integrin-dependent signaling pathway. Our studies support this hypothesis. Function-blocking antisera specific for beta(1) integrins block the neurite-promoting activity of Mn by 90-95%. Bioassays and biochemical studies with antisera specific for the alpha(v), alpha(5), or alpha(8) integrin subunit suggest that the alpha(v)beta(1) heterodimer is one of the principal beta(1) integrins mediating the response of PC12 cells to Mn. This is corroborated by studies in which Mn failed to induce neurite outgrowth in a clone of PC12 cells that does not express alpha(v) at levels detectable by immunoprecipitation or immunocytochemistry. SDS-PAGE analysis of biotinylated surface proteins immunoprecipitated from Mn-responsive PC12 cells, as well as confocal laser microscopy of PC12 immunostained for surface alpha(v) indicate that Mn increases the surface expression of alpha(v) integrins. This increase appears to be due in part to synthesis of alpha(v) since specific inhibitors of RNA and protein synthesis block the neurite-promoting activity of Mn. These data indicate that Mn induces neurite outgrowth in PC12 cells by upregulating alpha(v) integrins, suggesting that Mn potentially represents an additional mechanism for regulating the rate and direction of neurite outgrowth during development and regeneration.

Smooth muscle myosin light chain kinase expression in cardiac and skeletal muscle

The purpose of this study was to characterize myosin light chain kinase (MLCK) expression in cardiac and skeletal muscle. The only classic MLCK detected in cardiac tissue, purified cardiac myocytes, and in a cardiac myocyte cell line (AT1) was identical to the 130-kDa smooth muscle MLCK (smMLCK). A complex pattern of MLCK expression was observed during differentiation of skeletal muscle in which the 220-kDa-long or "nonmuscle" form of MLCK is expressed in undifferentiated myoblasts. Subsequently, during myoblast differentiation, expression of the 220-kDa MLCK declines and expression of this form is replaced by the 130-kDa smMLCK and a skeletal muscle-specific isoform, skMLCK in adult skeletal muscle. These results demonstrate that the skMLCK is the only tissue-specific MLCK, being expressed in adult skeletal muscle but not in cardiac, smooth, or nonmuscle tissues. In contrast, the 130-kDa smMLCK is ubiquitous in all adult tissues, including skeletal and cardiac muscle, demonstrating that, although the 130-kDa smMLCK is expressed at highest levels in smooth muscle tissues, it is not a smooth muscle-specific protein.

Alterations in expression of myosin and myosin light chain kinases in response to vascular injury

Histochemical analysis of balloon-injured rat carotid arteries revealed a coordinated expression of nonmuscle myosin heavy chain-A and -B (NM-A and NM-B) in response to injury. Expression of these nonmuscle myosin forms shifts from the media to the adventitia and intima. In contrast, expression of smooth muscle myosin heavy chain-1 (SM-1) within the media is not altered, whereas smooth muscle myosin heavy chain-2 (SM-2) expression declines. Western blotting shows a statistically significant increase in expression of NM-A that occurs within 6 h in response to carotid injury, suggesting this myosin form may be an appropriate experimental marker for proliferating, migrating cells in injured vessels. No overall change in the relative expression level of NM-B was detected, suggesting that compensatory declines in media expression are balanced by increases in the intima and adventitia. Expression of SM-1 did not change in response to injury, whereas the expression of SM-2 significantly declined between 24 h and 7 days. Expression of myosin light chain kinase is also negatively regulated, and the decline in its expression parallels downregulation of SM-2.

Diaphragmatic endometriosis

Endometriosis is a relatively common condition usually found in the pelvis. However, lesions do occur outside the pelvis and, more rarely, in the upper abdomen. In the case reported here, the patient presented with chronic right shoulder tip pain. The diagnosis of extrapelvic endometriosis is often not considered in such circumstances. This patient's symptoms were relieved by surgical excision of the diaphragmatic lesion.

Targeted expression of SV40 large T-antigen to visceral smooth muscle induces proliferation of contractile smooth muscle cells and results in megacolon

Many pathological conditions result from the proliferation and de-differentiation of smooth muscle cells leading to impaired contractility of the muscle. Here we show that targeted expression of SV40 large T-antigen to visceral smooth muscle cells in vivo results in increased smooth muscle cell proliferation without de-differentiation or decreased contractility. These data suggest that the de-differentiation and proliferation of smooth muscle cells, seen in many pathological states, may be independently regulated. In the T-antigen transgenic mice the increased smooth muscle cell proliferation results in thickening of the distal colon. Consequently the distal colon becomes hyper-contractile and impedes the flow of digesta through the colon resulting in enlargement of the colon oral to the obstruction. These transgenic mice thus represent a novel model of megacolon that results from increased smooth muscle cell proliferation rather than altered neuronal innervation.

Relation between direct detection of Chlamydia pneumoniae DNA in human coronary arteries at postmortem examination and histological severity (Stary grading) of associated atherosclerotic plaque

BACKGROUND

Numerous studies have suggested a link between Chlamydia pneumoniae infection, atherosclerosis, and coronary artery disease. However, it is still unclear whether C pneumoniae plays a causal role in the pathogenesis of these conditions. Accordingly, we have performed a systematic dissection of the 3 coronary arteries on 33 postmortem subjects and studied the relationship in individual artery segments between the presence of C pneumoniae DNA and the severity of associated atherosclerosis.

METHODS AND RESULTS

The prevalence of C pneumoniae DNA in arterial segments was determined by polymerase chain reaction (PCR) after controlling for the presence of PCR inhibitors. Atherosclerosis in each arterial segment was graded histologically with the Stary classification. C pneumoniae was detected by PCR in 78.8% of subjects, but there was no association between the presence of this DNA and cause of death or grade of atherosclerosis. When paired mild and severe atherosclerotic lesions within subjects were compared, mild lesions were as likely to be positive for C pneumoniae as severe lesions.

CONCLUSIONS

This study demonstrates that C pneumoniae can frequently be detected in atheromatous plaques in coronary arteries. However, its distribution did not correlate with severity or extent of disease.

Inferior vena caval resection with autogenous peritoneo-fascial patch graft caval repair: a new technique

BACKGROUND

In the course of oncological surgery, resection of the inferior vena cava (IVC) may be required to obtain an adequate resection margin and to offer the best opportunity of cure. The remaining defect in the IVC may be managed by: (i) primary repair which may lead to subsequent narrowing of the lumen, possibly leading to turbulent flow and thrombus formation; (ii) patch grafting of the defect, which may prevent narrowing. Several synthetic and biosynthetic materials are available as patch grafts and autologous pericardium has also been used.

METHODS

The harvesting and use of the autogenous peritoneo-fascial (APF) graft as an alternative caval patch graft material in the management of defects in the caval wall is proposed. Autogenous peritoneo-fascial caval patch graft repair in six patients was undertaken.

RESULTS

One patient with leiomyosarcoma secondaries in the liver eventually succumbed to the disease. The other five patients are clinically well with no evidence of IVC obstruction or venous aneurysms.

CONCLUSION

Preliminary results show that this new technique of utilizing an APF patch graft for caval repair is clinically a suitable alternative to current biosynthetic and synthetic materials and may in fact be superior in many aspects.

Catheter mounted coaxially moveable ablation electrode for the creation of linear transmural endocardial lesions

INTRODUCTION

Use of a novel ablation catheter for the creation of linear transmural endocardial lesions, which uses a coaxially moving ablation electrode mounted on the terminal portion of a catheter shaft and able to move axially for a distance of up to 4 cm, is reported.

METHODS AND RESULTS

The coaxially moving ablation electrode is moved by a sliding mechanism in the catheter handle. The distal portion of the catheter shaft is steerable. Bipolar or unipolar electrograms can be recorded from electrodes on the catheter tip and the coaxially moving ablation. Radiofrequency (RF) current is delivered to the coaxially moving ablation electrode with thermocouple temperature control. This ablation catheter was evaluated in five (30 to 65 kg) anesthetized pigs and introduced via the venous/arterial systems into the right and left atrium (1 lesion) (using the retrograde aortic approach). The catheter was maneuvered to bring the slide range into apposition with atrial endocardium. The coaxially moving ablation electrode was deployed to the terminal portion of the catheter's slide range and then withdrawn in 2-mm steps. RF current was delivered to the coaxially moving ablation electrode at each point (maximum temperature 70 degrees C). Postmortem examination of eight endocardial linear lesions (2.2 to 4.1 cm length) was made 1 to 3 hours after creation. Histopathologic examination confirmed transmural myocyte necrosis along the length of the lesion, that included the trabeculated right atrium.

CONCLUSION

We conclude that a catheter using a moveable electrode creates continuous linear transmural lesions and could find clinical application in the therapy of a variety of reentry tachycardia mechanisms.

Pyogenic liver abscess: a review of 10 years' experience in management

BACKGROUND

Over the past 15 years, diagnostic and interventional radiology techniques have allowed accurate localization of liver abscesses and image-guided percutaneous drainage. This review examines whether these technical advances improve clinical results and discusses the selection of treatment for patients with liver abscesses.

METHODS

Ninety-eight patients were treated for pyogenic liver abscess (PLA) at the Royal Prince Alfred Hospital, Sydney, between January 1987 and June 1997. The hospital records were examined and clinical presentation, laboratory, radiological and microbiological findings were recorded. Associations between these findings and failure of initial non-operative management were determined using odds ratios with 95% confidence intervals. Independent predictors were then determined by logistic regression. This analysis was repeated to determine factors associated with mortality.

RESULTS

Cholelithiasis and previous hepatobiliary surgery were the most frequently identifiable causes of PLA, each responsible in 15 patients. All 98 patients were treated with intravenous antibiotics and in 13 patients this was the only therapy. Of the remaining 85 patients, six proceeded straight to laparotomy and 79 had percutaneous drainage, of whom 15 required subsequent laparotomy. Factors predicting failure of initial non-operative management were unresolving jaundice, renal impairment secondary to clinical deterioration, multiloculation of the abscess, rupture on presentation and biliary communication. The overall hospital mortality rate was 8%.

CONCLUSION

Pyogenic liver abscess remains a disease with significant mortality. Image-guided percutaneous drainage is appropriate treatment for single unilocular PLA. Surgical drainage is more likely to be required in patients who have abscess rupture, incomplete percutaneous drainage or who have uncorrected primary pathology.

Chlamydia pneumoniae and atherosclerosis

OBJECTIVE

To review the literature for evidence that chronic infection with Chlamydia pneumoniae is associated with atherosclerosis and acute coronary syndromes.

DATA SOURCES

MEDLINE and Institute of Science and Information bibliographic databases were searched at the end of September 1998. Indexing terms used were chlamydi*, heart, coronary, and atherosclerosis. Serological and pathological studies published as papers in any language since 1988 or abstracts since 1997 were selected.

DATA EXTRACTION

It was assumed that chronic C pneumoniae infection is characterised by the presence of both specific IgG and IgA, and serological studies were examined for associations that fulfilled these criteria. Pathological studies were also reviewed for evidence that the presence of C pneumoniae in diseased vessels is associated with the severity and extent of atherosclerosis.

DATA SYNTHESIS

The majority of serological studies have shown an association between C pneumoniae and atherosclerosis. However, the number of cases in studies that have reported a positive association when using strict criteria for chronic infection is similar to the number of cases in studies which found no association. Nevertheless, the organism is widely found in atherosclerotic vessels, although it may not be at all diseased sites and is not confined to the most severe lesions. Rabbit models and preliminary antibiotic trials suggest that the organism might exacerbate atherosclerosis.

CONCLUSION

More evidence is required before C pneumoniae can be accepted as playing a role in atherosclerosis. Although use of antibiotics in routine practice is not justified, large scale trials in progress will help to elucidate the role of C pneumoniae.

The prevalence of Chlamydia pneumoniae in atherosclerotic and nonatherosclerotic blood vessels of patients attending for redo and first time coronary artery bypass graft surgery

OBJECTIVES

To determine if Chlamydia pneumoniae (C. pneumoniae) is more prevalent in atherosclerotic compared with normal blood vessels of patients requiring redo and first time coronary artery bypass graft surgery (CABG).

BACKGROUND

Serological and pathological studies have associated atherosclerosis with C. pneumoniae infection. As atherosclerosis is one of the causes of graft failure following CABG, then it may be expected that the prevalence of the organism in failed grafts and diseased native vessels should be greater than in the new grafts.

METHODS

Endarterectomy specimens and failed and new grafts were collected from 49 patients with late graft failure. Endarterectomy specimens and new grafts were also collected from nine patients having first time CABG. The presence of C. pneumoniae DNA was then checked for using a nested polymerase chain reaction.

RESULTS

The prevalence of C. pneumoniae DNA in failed venous grafts (38.2%) was similar to that in endarterectomy specimens from native coronary arteries (38.5%) and greater than that in new saphenous vein grafts (11.8%). However, it was similar to that in new internal mammary artery grafts (30.0%). Also, the interval between surgery in redo patients was the same regardless of whether C. pneumoniae was present or not.

CONCLUSIONS

Cross sectional studies cannot determine whether C. pneumoniae is a cause of atherosclerosis since they do not show whether infection precedes or follows its development. However, our results suggest that the organism is not an important factor in graft failure or atherosclerosis.

Post-mortem examination after cardiac surgery

Following a recent enquiry into surgery at a paediatric cardiac centre in England, there will be substantial changes in the way that the success and failure of surgical procedures will be monitored and investigated. Post-mortem examinations on patients dying after cardiac surgery are likely to be performed and reported in more detail. This review describes the protocol that we have developed and summarizes recent clinical and pathological studies that have increased our understanding of postoperative pathophysiology. Close attention should be paid to the history, particularly the operation note. Cardiac failure is the commonest cause of death. We believe this is a clinicopathological diagnosis and provide definitions of preoperative and perioperative cardiac failure. Haemorrhage, stroke, pulmonary emboli and infection are other important causes of death. Methods of dissection are suggested for bypass grafts and valve replacements. Two recent studies show that the post-mortem examination provides answers to most clinical questions and reveals an unexpected cause of death in 10-15% of patients. There are limitations however: an incomplete or indeterminate cause of death is found in 14-25% of patients, most commonly sudden clinically unexplained death or clinically unexplained cardiac failure soon after surgery.

Angiogenesis in pathological and surgical scars

We identified immunohistochemically vessels within cutaneous scars to test the hypothesis that they are qualitatively and quantitatively different in pathological and normally healing scars. The vascular density within and adjacent to 58 cutaneous scars was measured on histological sections stained for factor VIII-related antigen. Four scar types were studied; surgical scars (n = 25), hypertrophic scars (n = 10), keloid (n = 12), and periocular scars (n = 11). Statistical analyses were performed to test the hypothesis that vessel numbers were different in the varying types of scar. Results were also compared with mast cell counts previously derived from the same tissues. A significant reduction was found in the vascular density in keloids compared with surgical and hypertrophic scars (P < .05). No correlation was found between the vascular density and the number of mast cells in the lesions. We have shown quantitatively that keloids have a reduced vascular component compared with hypertrophic scars and normally healing surgical scars at periocular and systemic sites. The formation of keloid scars may be related to their reduced level of vascularization mediated through tissue hypoxia.

Mast cell subpopulations in the synovial tissue of patients with osteoarthritis: selective increase in numbers of tryptase-positive, chymase-negative mast cells

Although there is relatively little evidence of inflammation in osteoarthritis (OA), increases in mast cell numbers and mast cell activation are prominent features of the synovial tissue. As little is known of the types of mast cells which may be involved, the numbers and distribution of mast cell subpopulations have been investigated as defined according to their content of proteases. Tissue was obtained from patients with OA undergoing total knee replacement surgery (n = 14) and from control subjects either post-mortem (n = 11) or following leg amputation for peripheral vascular disease (n = 3); a double-labelling immunocytochemical procedure with monoclonal antibodies specific for tryptase and chymase was applied to identify those mast cells which contain both tryptase and chymase (MCTC) and those with tryptase but not chymase (MCT). There was considerable variation between individual tissues and between sites of tissue sampling, but cells of the MCTC subset were predominant in the synovial layer of both groups of subjects without joint disease, accounting for some 60 per cent of all mast cells present. In tissue from OA patients, however, there appeared to have been a striking shift in the relative proportions of mast cells from the MCTC to the MCT phenotype, with many more MCT cells present in the synovial tissues of OA patients (median 53 MCT/mm2) than in tissue from post-mortem (7.5 MCT/mm2, P < 0.0001) or amputation controls (12 MCT/mm2). In contrast, numbers of synovial MCTC cells in the synovium of OA patients (20 MCTC/mm2) differed little from those in either of the control groups (both 12 MCTC/mm2). In several other conditions, the MCT cells have been linked with inflammatory events, but it seems that in OA, other factors may be operating to induce a selective expansion of this subpopulation.

Laparoscopic subtotal cholecystectomy in patients with complicated acute cholecystitis or fibrosis

BACKGROUND

The open subtotal cholecystectomy technique has simplified removal of the difficult gallbladder. Increasing laparoscopic experience has made laparoscopic subtotal cholecystectomy (LSC) a feasible option in patients with complicated acute or chronic cholecystitis.

METHODS

LSC was performed in 29 patients with severe inflammation or fibrosis of the gallbladder associated with gallstone disease over a 23-month period. These 29 patients (mean age 53 years; 22 women) constituted 8.5 per cent of the total number of laparoscopic cholecystectomies performed (n = 340) and 15.6 per cent of 186 patients with acute cholecystitis. Eighteen patients in the latter group underwent conversion to open cholecystectomy. The indications for LSC were acute cholecystitis/empyema (n = 23) and severe fibrosis (n = 6).

RESULTS

The cystic duct was either clipped before division (n = 15), sutured (n = 2) or ligated using an Endoloop (n = 10). In two patients the gallbladder bed was drained without isolating the cystic duct. The posterior wall of the gallbladder was left intact to avoid excessive bleeding or damage to bile ducts in the gallbladder bed. A suction drain was inserted in 14 cases. Median operating time was 73 (range 45-130) min. One patient died after operation from a myocardial infarction. Six patients had local complications (two haematomas, three bile leaks, one minor wound sepsis) and nine developed respiratory infections. Median hospital stay was 5 (range 2-28) days.

CONCLUSION

LSC is a safe, relatively simple and definitive procedure allowing removal of a difficult gallbladder and reducing the need for open conversion or cholecystostomy in the majority of patients.

Mast cells in pathological and surgical scars

AIM

To investigate the role of mast cells in surgical and pathological scar reactions by their identification and quantification using immunohistochemistry.

METHODS

Surgical scars and pathological scar reactions were stained immunohistochemically for tryptase to identify mast cells. These were quantified in the scar tissue and surrounding dermis. Statistical analyses were performed to test the hypothesis that mast cell numbers were different in the varying types of scar reaction.

RESULTS

A significant difference was found between the mean number of mast cells in periocular scars compared with keloids, hypertrophic scars, and surgical scars from other sites (p < 0.05). No significant difference was found in mast cell numbers between the other scar types either within the lesions or surrounding dermis. There were significantly more mast cells in the dermis than in the scar tissue itself, except for the small group of periocular scars. The ratio of mast cells in the lesion compared with the dermis was not significantly different between the scar types, except for the periocular scars.

CONCLUSIONS

Mast cell numbers are similar in and around keloid, hypertrophic, and surgical scars. The increased number of mast cells at periocular scar sites was contrary to expectation since keloids are rare at this site. Absolute mast cell numbers may not be an accurate measure of tissue concentrations of active mast cell products. Further comparisons between immunological characteristics of keloid and periocular scars may elucidate specific immunological abnormalities of keloid scars, and this has implications for the development of immunotherapy.

Aberrant diagnoses by individual surgical pathologists

Methods of auditing the performance of histopathologists, such as external and internal quality assurance, clinicopathological conferences, and "double-reporting" of microscopic slides, show significant diagnostic errors in at least 1.2% of reports. Although some of these are in well-recognized areas of difficulty, such as melanoma or lymphoma, most errors are in common biopsy specimens. We have developed a method that compares diagnostic patterns of individual histopathologists. This aims to identify specific diagnoses that a pathologist makes more or less frequently than other colleagues and enables the individual to reflect on his or her own histologic expertise in reporting on specific biopsy results. The bottom line diagnoses of transurethral resection of prostate specimens; rectal, gastric, and bladder biopsy samples; and endometrial curettages were analyzed retrospectively. Analyses were performed on diagnoses made by at least 15 pathologists on each specimen type and expressed as a standardized ratio (SR) with 95% confidence intervals (CI). An SR of 1.0 indicated a pattern of diagnosis matching the combined pattern of other colleagues. An SR <1.0 indicated relative "underdiagnosis" and an SR >1.0 indicated relative "overdiagnosis." Diagnostic rates of individual pathologists whose CIs did not straddle the value of 1.0 were considered aberrant, although not necessarily incorrect. The 47 of 226 (20.8%) aberrant SRs included four pathologists' diagnoses of prostatic carcinoma, three each of endometrial, rectal, and bladder carcinoma, and one of gastric malignancy. This method, which could easily be automated and used regionally or nationally, should provide pathologists with a profile of their diagnostic patterns in comparison with their peers.

Localization of an actin binding domain in smooth muscle myosin light chain kinase

Phosphorylation of the regulatory light chain of myosin II by myosin light chain kinase is important for regulating many contractile processes. Smooth muscle myosin light chain kinase has been shown to be associated with both actin and myosin filaments in vitro and in vivo. In this report we define an actin binding region by using molecular deletions to generate recombinant mutant proteins that were analyzed by co-sedimentation with F-actin. An actin binding region restricted to residues 2-42 in the amino terminus of the rabbit smooth muscle myosin light chain kinase was identified.

Prospective study of the value of necropsy examination in early death after cardiac surgery

OBJECTIVE

To assess the value of necropsy examination in patients dying soon after cardiac surgery, particularly the proportion of clinical questions answered by the necropsy, the frequency of major unexpected findings, and the limitations of the procedure.

DESIGN

A three year prospective study of necropsy examinations in adult patients dying before discharge or within 30 days of cardiac surgery performed under cardiopulmonary bypass in one hospital.

SETTING

Tertiary referral centre.

RESULTS

123 of 2781 patients (4.4%) died in the early postoperative period, and necropsy examination was performed in 108 of these (88%). The mortality after emergency procedures (18%) was much higher than after routine operations (2.6%). The main causes of death were cardiac failure (52%), haemorrhage (14%), cerebral disease (6%), and pulmonary emboli (5%). The necropsy changed the stated cause of death in 16 patients (15%), and answered clinical questions in 24 of 38 patients. In 15 patients necropsy examination did not provide a full explanation of death. Most of these patients died of cardiac failure soon after surgery or were sudden unexpected deaths.

CONCLUSIONS

Necropsy examination in patients dying early after cardiac surgery is valuable as it answers the majority of clinical questions, and shows unexpected findings in a significant proportion of cases.

Percutaneous microcoil embolization of intraperitoneal intrahepatic and extrahepatic biliary fistulas

BACKGROUND

Persistent intraperitoneal biliary fistulas are associated with significant morbidity and mortality. Percutaneous drainage, stenting, and endoscopic sphincterotomy or embolization of biliary radicals have largely replaced the need for hepatic resection or biliary reconstruction in managing such fistulas. When endoscopy is contraindicated, a previously undescribed technique of percutaneous embolization of intrahepatic and extrahepatic biliary fistula following penetrating liver trauma, and orthotopic liver transplant and its application in three patients, will be discussed.

METHODS

Embolization procedures were performed by an interventional radiologist. Percutaneous trans-hepatic cholangiography via a standard right-side approach or via tube cholangiography was initially performed and the fistula defined. Coaxial catheter systems were used (5 Fr angiography catheters and Tracker 18 infusion catheters), and were positioned within the biliary tree as close as possible to the origin of the fistula. Embolization was performed using vascular Embolization 28 coils (WA Cook) 2-3 mm x 2 cm coils, straight Hilal 18 embolization coils (WA Cook) 5-7 cm, as well as Gelfoam (Upjohn) 1 mm pellets, and Histoacryl (B. Braun) 0.25-1 mL. Occlusion of the duct was confirmed by a selective intrahepatic cholangiogram. In cases of multiple fistulas several embolizations were performed at subsequent procedures. Follow-up is over 13 months without adverse event.

RESULTS

The technique was used in the three cases and was successful in all. A peripheral biliary fistula required embolization twice and two cystic leaks were cured after a single attempt.

CONCLUSIONS

Percutaneous embolization of biliary fistulas provides a management option in cases where conservative treatment has failed and other techniques are relatively contraindicated. The technique is effective and safe in skilled hands, and avoids major surgery. The long-term effect of microcoils in the biliary tree is unknown.

Myosin light chain kinase in endothelium: molecular cloning and regulation

The phosphorylation of myosin light chains by myosin light chain kinase (MLCK) is a key event in agonist-mediated endothelial cell gap formation and vascular permeability. We now report the cloning and expression of a nonmuscle MLCK isoform in cultured endothelium. Screening of a human endothelial cell cDNA library identified a 7.7 kb cDNA with substantial (> 95%) homology to the coding region of the rabbit and bovine smooth muscle (SM) MLCK (amino acid #923-1913) as well as with the reported avian nonmuscle MLCK (65-70% homology). Sequence analysis also identified, however, a 5' stretch of novel sequence (amino acids #1-922) which is not contained in the open reading frame of mammalian SM MLCK, and is only 58% homologous to the avian fibroblast MLCK sequence. Immunoprecipitation with NH2-specific antisera revealed a 214 kD high molecular weight MLCK in bovine and human endothelium which exhibits MLC phosphorylation properties. Amino acid sequence analysis revealed endothelial MLCK consensus sequences for a variety of protein kinases including highly conserved potential phosphorylation sites for cAMP-dependent protein kinase A (PKA) in the CaM-binding region. Augmentation of intracellular cAMP levels markedly enhanced MLCK phosphorylation (2.5-fold increase) and reduced kinase activity in MLCK immunoprecipitates (4-fold decrease). These data suggest potentially novel mechanisms of endothelial cell contraction and barrier regulation.

Regulation of cell motility by mitogen-activated protein kinase

Cell interaction with adhesive proteins or growth factors in the extracellular matrix initiates Ras/mitogen-activated protein (MAP) kinase signaling. Evidence is provided that MAP kinase (ERK1 and ERK2) influences the cells' motility machinery by phosphorylating and, thereby, enhancing myosin light chain kinase (MLCK) activity leading to phosphorylation of myosin light chains (MLC). Inhibition of MAP kinase activity causes decreased MLCK function, MLC phosphorylation, and cell migration on extracellular matrix proteins. In contrast, expression of mutationally active MAP kinase kinase causes activation of MAP kinase leading to phosphorylation of MLCK and MLC and enhanced cell migration. In vitro results support these findings since ERK-phosphorylated MLCK has an increased capacity to phosphorylate MLC and shows increased sensitivity to calmodulin. Thus, we define a signaling pathway directly downstream of MAP kinase, influencing cell migration on the extracellular matrix.

Diagnostic pitfalls and therapeutic strategies in the treatment of pancreatic duct haemorrhage

Haemorrhage via the pancreatic duct, a rare cause of upper gastrointestinal bleeding (GIB), often poses a diagnostic dilemma. We analysed our experience with 10 patients (8 men, 2 women; mean age 44 years, range 34-62) treated during a 12 year period. All had a history of alcohol abuse and presented with major upper GIB requiring a median of 8 units (range 2-40) blood transfusion. Nine had upper abdominal pain at the time of admission and nine had a history of pancreatitis. Upper gastroduodenal endoscopy (median 4; range 1-9), was diagnostic in only one. Side-viewing endoscopy showed bleeding from the pancreatic duct in 7 of 8 patients. Visceral aneurysms were demonstrated in 7 of 9 patients in whom coeliac angiography was carried out: (splenic artery 4, gastroduodenal artery 2, and pancreaticoduodenal artery 1). Two of 4 selective embolisations were successful. Six patients underwent distal pancreatectomy, 1 had gastroduodenal artery ligation and 1 died of coagulopathy following a total pancreatectomy. Pancreatic duct haemorrhage should be considered in patients with unexplained recurrent upper GIB, alcohol abuse and epigastric pain, particularly in those with established chronic pancreatitis. Selective angiography is essential for diagnosis and management. For bleeding sites in the head of the pancreas, embolisation should be attempted to avoid major resection. Distal pancreatectomy is preferred for splenic artery lesions.

Massive arterial haemorrhage from the lower gastrointestinal tract

We have studied the clinical, radiological and pathological features of three patients with recurrent massive lower gastrointestinal arterial haemorrhage. Case 1 was an example of Dieulafoy's vascular malformation within the proximal ascending colon in a 46-year-old woman. Cases 2 and 3 were men aged 81 and 83 years with arterial erosions contained within small mucosal diverticula in the hepatic flexure and descending colon, respectively. All three patients presented with recurrent acute episodes of massive lower gastrointestinal haemorrhage. Selective mesenteric angiography was performed in cases 1 and 3 to localize the bleeding point in both patients. The features were very different to those of angiodysplasia, lacking the tuft of abnormal vessels and the early venous filling phase commonly seen in the latter condition. The patients were all successfully treated by partial colectomy. The aetiology of Dieulafoy's vascular malformation remains unclear. The ruptured arteries in cases 2 and 3 shared many histological features with the Dieulafoy lesion in case 1. The lesions in cases 1 and 2 were associated with recent oral non-steroidal anti-inflammatory therapy, suggesting coincidental mucosal ulceration as a contributory factor.

Hepatic resection with vascular isolation and routine supraceliac aortic clamping

BACKGROUND

Hepatic resection with total vascular isolation has been reported to reduce hemorrhage. Addition of supraceliac aortic clamping putatively avoids hemodynamic instability, but may increase morbidity.

METHODS

This technique was used in 99 major liver resections utilizing scalpel division and suture hemostasis.

RESULTS

Livers were normal in 86 patients, cirrhotic with no portal hypertension in 5, and cirrhotic with portal hypertension in 8. There was 1 death in 91 patients with no portal hypertension due to hepatic failure or bleeding esophageal varices. There were 59 hemihepatectomies and 40 segmentectomies. Median operating time was 145 and 110 minutes, respectively, and mean transfused blood was 4 and 0 units, respectively, with minimal morbidity.

CONCLUSIONS

Use of total hepatic vascular isolation with routine supraceliac aortic clamping is a safe and expedient method of hepatic resection that limits blood loss and maintains hemodynamic stability, but does not increase morbidity. However, the presence of portal hypertension precludes safe resection.

Expression of a novel myosin light chain kinase in embryonic tissues and cultured cells

A novel, 208-kDa myosin light chain kinase (MLCK) distinct from smooth muscle and non-muscle MLCK has been identified by cross-reaction to two antibodies raised against smooth muscle MLCK. Additional antibodies directed against the amino and carboxyl termini of the smooth muscle MLCK do not react with the 208-kDa MLCK, suggesting these regions are distinct. 208-kDa MLCK phosphorylates 20-kDa myosin light chains in a Ca2+/calmodulin-dependent manner, consistent with it being a member of the MLCK family. Expression of 208-kDa MLCK and smooth muscle MLCK appears to be inversely regulated, with 208-kDa MLCK being most abundant during early development and declining at birth. In contrast, expression of smooth muscle MLCK is relatively low early during development and increases to become the predominant MLCK detected in all adult smooth and non-muscle tissues. The developmental expression pattern of the 208-kDa MLCK suggests this form be named, embryonic MLCK.

Prospective audit of mucosal biopsy specimens of the gastrointestinal tract

AIMS

To determine why mucosal biopsy specimens of the gastrointestinal tract were taken and whether they were justified on clinical or pathological grounds.

METHODS

A prospective audit of 190 consecutive biopsy specimens received in a university hospital histology department over six weeks.

RESULTS

The 31 separate presenting symptoms included diarrhoea (34%), abdominal pain (16%) and rectal bleeding (15%). In 41% (78/190) the histology was normal, 28% (53/190) showed inflammatory changes and 11% 21/190) carcinoma. A clear justification for the procedure was identified in over 90% (171/190) of patients. In 36% (68/190) there was a change in patient management on receipt of biopsy reports and further investigations were ordered in 29% (55/190). The mean time taken to report biopsy specimens was 4.7 working days and there was no difference between the reporting time of a pathologist compared with a consultant or a trainee.

CONCLUSIONS

There is no evidence that mucosal biopsy specimens are taken unnecessarily.

Sudden death from coronary artery dissection

Spontaneous dissection of the coronary arteries is an uncommon condition that may lead to sudden, fatal coronary artery occlusion. Three cases of sudden death attributable to coronary artery occlusion are presented. Dissection was associated with Marfan's syndrome in the first case, and occurred three weeks postpartum in the second case. In case 1, dissection occurred within the intima, and was not associated with an inflammatory cell infiltrate. In cases 2 and 3, dissection occurred between the tunica media and the external elastic lamina, and was associated with a mixed inflammatory infiltrate, rich in eosinophils, T lymphocytes, and histiocytes. The spatial limitation of the inflammatory infiltrate to the adventitial compartment, together with the absence of inflammation in case 1, suggests a reactive origin rather than a causative role for the inflammatory cells. Detailed examination of serial blocks of any coronary artery occlusion is essential in young patients.