Annotation-free prediction of treatment-specific tissue outcome from 4D CT perfusion imaging in acute ischemic stroke

Acute ischemic stroke is a critical health condition that requires timely intervention. Following admission, clinicians typically use perfusion imaging to facilitate treatment decision-making. While deep learning models leveraging perfusion data have demonstrated the ability to predict post-treatment tissue infarction for individual patients, predictions are often represented as binary or probabilistic masks that are not straightforward to interpret or easy to obtain. Moreover, these models typically rely on large amounts of subjectively segmented data and non-standard perfusion analysis techniques. To address these challenges, we propose a novel deep learning approach that directly predicts follow-up computed tomography images from full spatio-temporal 4D perfusion scans through a temporal compression. The results show that this method leads to realistic follow-up image predictions containing the infarcted tissue outcomes. The proposed compression method achieves comparable prediction results to using perfusion maps as inputs but without the need for perfusion analysis or arterial input function selection. Additionally, separate models trained on 45 patients treated with thrombolysis and 102 treated with thrombectomy showed that each model correctly captured the different patient-specific treatment effects as shown by image difference maps. The findings of this work clearly highlight the potential of our method to provide interpretable stroke treatment decision support without requiring manual annotations.

Identifying Biases in a Multicenter MRI Database for Parkinson's Disease Classification: Is the Disease Classifier a Secret Site Classifier?

Sharing multicenter imaging datasets can be advantageous to increase data diversity and size but may lead to spurious correlations between site-related biological and non-biological image features and target labels, which machine learning (ML) models may exploit as shortcuts. To date, studies analyzing how and if deep learning models may use such effects as a shortcut are scarce. Thus, the aim of this work was to investigate if site-related effects are encoded in the feature space of an established deep learning model designed for Parkinson's disease (PD) classification based on T1-weighted MRI datasets. Therefore, all layers of the PD classifier were frozen, except for the last layer of the network, which was replaced by a linear layer that was exclusively re-trained to predict three potential bias types (biological sex, scanner type, and originating site). Our findings based on a large database consisting of 1880 MRI scans collected across 41 centers show that the feature space of the established PD model (74% accuracy) can be used to classify sex (75% accuracy), scanner type (79% accuracy), and site location (71% accuracy) with high accuracies despite this information never being explicitly provided to the PD model during original training. Overall, the results of this study suggest that trained image-based classifiers may use unwanted shortcuts that are not meaningful for the actual clinical task at hand. This finding may explain why many image-based deep learning models do not perform well when applied to data from centers not contributing to the training set.

Providing clinical context to the spatio-temporal analysis of 4D CT perfusion to predict acute ischemic stroke lesion outcomes

Acute ischemic stroke is a leading cause of mortality and morbidity worldwide. Timely identification of the extent of a stroke is crucial for effective treatment, whereas spatio-temporal (4D) Computed Tomography Perfusion (CTP) imaging is playing a critical role in this process. Recently, the first deep learning-based methods that leverage the full spatio-temporal nature of perfusion imaging for predicting stroke lesion outcomes have been proposed. However, clinical information is typically not integrated into the learning process, which may be helpful to improve the tissue outcome prediction given the known influence of various factors (i.e., physiological, demographic, and treatment factors) on lesion growth. Cross-attention, a multimodal fusion strategy, has been successfully used to combine information from multiple sources, but it has yet to be applied to stroke lesion outcome prediction. Therefore, this work aimed to develop and evaluate a novel multimodal and spatio-temporal deep learning model that utilizes cross-attention to combine information from 4D CTP and clinical metadata simultaneously to predict stroke lesion outcomes. The proposed model was evaluated using a dataset of 70 acute ischemic stroke patients, demonstrating significantly improved volume estimates (mean error = 19 ml) compared to a baseline unimodal approach (mean error = 35 ml, p< 0.05). The proposed model allows generating attention maps and counterfactual outcome scenarios to investigate the relevance of clinical variables in predicting stroke lesion outcomes at a patient level, helping to provide a better understanding of the model's decision-making process.

Predicting treatment-specific lesion outcomes in acute ischemic stroke from 4D CT perfusion imaging using spatio-temporal convolutional neural networks

For the diagnosis and precise treatment of acute ischemic stroke, predicting the final location and volume of lesions is of great clinical interest. Current deep learning-based prediction methods mainly use perfusion parameter maps, which can be calculated from spatio-temporal (4D) CT perfusion (CTP) imaging data, to estimate the tissue outcome of an acute ischemic stroke. However, this calculation relies on a deconvolution operation, an ill-posed problem requiring strong regularization and definition of an arterial input function. Thus, improved predictions might be achievable if the deep learning models were applied directly to acute 4D CTP data rather than perfusion maps. In this work, a novel deep spatio-temporal convolutional neural network is proposed for predicting treatment-dependent stroke lesion outcomes by making full use of raw 4D CTP data. By merging a U-Net-like architecture with temporal convolutional networks, we efficiently process the spatio-temporal information available in CTP datasets to make a tissue outcome prediction. The proposed method was evaluated on 147 patients using a 10-fold cross validation, which demonstrated that the proposed 3D+time model (mean Dice=0.45) significantly outperforms both a 2D+time variant of our approach (mean Dice=0.43) and a state-of-the-art method that uses perfusion maps (mean Dice=0.38). These results show that 4D CTP datasets include more predictive information than perfusion parameter maps, and that the proposed method is an efficient approach to make use of this complex data.

Perfusion Changes in Acute Stroke Treated with Theophylline as an Add-on to Thrombolysis : A Randomized Clinical Trial Subgroup Analysis

PURPOSE

Theophylline has been suggested to have a neuroprotective effect in ischemic stroke; however, results from animal stroke models and clinical trials in humans are controversial. The aim of this study was to assess the effect of theophylline on the cerebral perfusion with multiparametric magnetic resonance imaging (MRI).

METHODS

The relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and relative mean transit time (rMTT) in the infarct core, penumbra, and unaffected tissue were measured using multi-parametric MRI at baseline and 3‑h follow-up in patients treated with theophylline or placebo as an add-on to thrombolytic therapy.

RESULTS

No significant differences in mean rCBF, rCBV, and rMTT was found in the penumbra and unaffected tissue between the theophylline group and the control group between baseline and 3‑h follow-up. In the infarct core, mean rCBV increased on average by 0.05 in the theophylline group and decreased by 0.14 in the control group (p < 0.04). Mean rCBF and mean rMTT in the infarct core were similar between the two treatment groups.

CONCLUSION

The results indicate that theophylline does not change the perfusion in potentially salvageable penumbral tissue but only affects the rCBV in the infarct core. In contrast to the penumbra, the infarct core is unlikely to be salvageable, which might explain why theophylline failed in clinical trials.

Machine Learning-Based Prediction of Brain Tissue Infarction in Patients With Acute Ischemic Stroke Treated With Theophylline as an Add-On to Thrombolytic Therapy: A Randomized Clinical Trial Subgroup Analysis

Background and Purpose: The theophylline in acute ischemic stroke trial investigated the neuroprotective effect of theophylline as an add-on to thrombolytic therapy in patients with acute ischemic stroke. The aim of this pre-planned subgroup analysis was to use predictive modeling to virtually test for differences in the follow-up lesion volumes.

Materials and Methods: A subgroup of 52 patients from the theophylline in acute ischemic stroke trial with multi-parametric MRI data acquired at baseline and at 24-h follow-up were analyzed. A machine learning model using voxel-by-voxel information from diffusion- and perfusion-weighted MRI and clinical parameters was used to predict the infarct volume for each individual patient and both treatment arms. After training of the two predictive models, two virtual lesion outcomes were available for each patient, one lesion predicted for theophylline treatment and one lesion predicted for placebo treatment.

Results: The mean predicted volume of follow-up lesions was 11.4 ml (standard deviation 18.7) for patients virtually treated with theophylline and 11.2 ml (standard deviation 17.3) for patients virtually treated with placebo (p = 0.86).

Conclusions: The predicted follow-up brain lesions for each patient were not significantly different for patients virtually treated with theophylline or placebo, as an add-on to thrombolytic therapy. Thus, this study confirmed the lack of neuroprotective effect of theophylline shown in the main clinical trial and is contrary to the results from preclinical stroke models.

Supervised machine learning tools: a tutorial for clinicians

In an increasingly data-driven world, artificial intelligence is expected to be a key tool for converting big data into tangible benefits and the healthcare domain is no exception to this. Machine learning aims to identify complex patterns in multi-dimensional data and use these uncovered patterns to classify new unseen cases or make data-driven predictions. In recent years, deep neural networks have shown to be capable of producing results that considerably exceed those of conventional machine learning methods for various classification and regression tasks. In this paper, we provide an accessible tutorial of the most important supervised machine learning concepts and methods, including deep learning, which are potentially the most relevant for the medical domain. We aim to take some of the mystery out of machine learning and depict how machine learning models can be useful for medical applications. Finally, this tutorial provides a few practical suggestions for how to properly design a machine learning model for a generic medical problem.

Emergency care of patients receiving non-vitamin K antagonist oral anticoagulants

Non-vitamin K antagonist oral anticoagulants (NOACs), which inhibit thrombin (dabigatran) and factor Xa (rivaroxaban, apixaban, edoxaban) have been introduced in several clinical indications. Although NOACs have a favourable benefit-risk profile and can be used without routine laboratory monitoring, they are associated-as any anticoagulant-with a risk of bleeding. In addition, treatment may need to be interrupted in patients who need surgery or other procedures. The objective of this article, developed by a multidisciplinary panel of experts in thrombosis and haemostasis, is to provide an update on the management of NOAC-treated patients who experience a bleeding episode or require an urgent procedure. Recent advances in the development of targeted reversal agents are expected to help streamline the management of NOAC-treated patients in whom rapid reversal of anticoagulation is required.

Tamoxifen-induced hypertriglyceridaemia

We report seven cases of breast adenocarcinoma and hypertriglyceridaemia associated with the use of tamoxifen. Two cases presented with life-threatening acute pancreatitis. Two cases show a rise in serum triglycerides (TG) after starling tamoxifen. Five patients had some degree of insulin resistance or diabetes which may have aggravated the hypertriglyceridaemia. One additional patient had an apolipoprotein phenotype associated with hypertriglyceridaemia. Fibrates effectively reduced serum TG levels. In general, tamoxifen improves the lipid profile and this may account for the reduction in coronary events in patients taking this drug. However, a rise in serum TG levels has been documented in several studies. Our reports suggest that it is important to screen patients on tamoxifen since hypertriglyceridaemia could cause potentially fatal acute pancreatitis or increase the risk of developing ischaemic heart disease.

Secondary prevention and referral of elderly patients to a cardiovascular lipid service

The burden of cardiovascular disease in the elderly has increased interest in lipid profiles which retain associations with outcome except at extreme age and for which management has benefits at least in secondary prevention. The source, clinical and laboratory background of 90 male and 120 female consecutive referrals age >70 years to a specialist cardiovascular lipid service have been analysed. Main sources were vascular surgery 47%, cardiology 9% and general practice 41% with 6% referred through routine health checks. Presenting lipids (mM: mean+/-S.D.) were: males: cholesterol 6.9+/-1.7, triglycerides 2.3+/-1.5, HDL 1.2+/-0.3; females: cholesterol 7.8+/-1.4, triglycerides 2.1+/-1.3, HDL 1.5+/-0.5, consistent with greater awareness of lipid-related problems in males but significant vascular disease in females. Secondary lipemia was defined in 131/210, 62.3% of patients (83 recognised before clinic presentation, 48 found at follow-up, mainly diabetes). Significant vascular disease was identified in 166/210 patients, significant other risk factors in another 35 patients. Levels of lipoprotein(a) were widely distributed for all groups, but elevated against population profiles for all groups with vascular disease. Referrals were monitored and not routinely accepted: reassuringly most then accepted were justified through atheroma-related disease and opportunities for secondary prevention, with little additional burden through untargeted routine health checks. Recognition of and management of secondary lipemia and obesity were however incomplete.

Continence assessment in primary care: what is the next step?

There are many assessment 'forms' available for the collection of information in relation to bladder dysfunction. In many cases such forms have not been fully validated and should only be considered on a face validity basis. Validated symptom scores are available but these are generally used within specific areas of urology, e.g. lower urinary tract symptom scores for prostate screening. This article explores the need for an improved validated assessment and symptom scoring tool for nurses within primary care, to enable nurses to establish a preliminary diagnosis in adult patients presenting with bladder symptoms.

Devising an effective general nursing continence assessment tool

Incontinence assessment forms are routinely used by nurses in order to implement the appropriate management, treatment and referral of patients suffering from bladder dysfunction. A thorough literature search using recognized databases revealed that no specific work has been carried out in respect of validating symptom scoring assessment tools for nurses. Validated symptom scores are available but these are generally used within specific areas of medicine, e.g. prostatic screening incorporates lower urinary tract symptom scores, and physiotherapy, to measure pelvic floor tone. This article examines the need for validity and symptom scoring within a general nursing incontinence assessment tool.

Indwelling catheters: practical guidelines for catheter blockage

Catheterization is a medical decision and requires a team approach involving, where possible, the patient and carer, as well as those professionals administering care. Catheterization and subsequent effective catheter drainage is associated with many dangers and complications (Lowthian, 1998) and therefore the decision to catheterize someone should not be taken lightly. Catheterization should only be used in intractable incontinence when all other measures have been tried and proven to be ineffective. This article identifies some of the problems associated with the care of patients with indwelling catheters in the community setting, and examines the issues that can cause pain, distress and discomfort to patients. It looks at the various types of solutions to problems associated with catheterization. Case histories are used to illustrate the types of patients who may have been catheterized. It is hoped that nurses can learn from these examples, so that they will not only cope more effectively with these individuals, but also observe their own practice when initiating indwelling catheterization and developing care packages.

Oculoauriculovertebral abnormalities in children of diabetic mothers

Maternal diabetes is known to have teratogenic effects. Malformations including neural tube defects, caudal dysgenesis, vertebral defects, congenital heart defects, femoral hypoplasia, and renal anomalies are described in infants of diabetic mothers. However, craniofacial anomalies have rarely been reported in such infants. Here we document craniofacial anomalies of patients born to diabetic mothers. We describe two patient populations: individuals evaluated through our genetics services for multiple malformations and individuals identified through a database search in our craniofacial clinic. The first group consists of 14 individuals evaluated in our genetics clinics who were born to diabetic mothers and had craniofacial anomalies. The second group consists of seven individuals who were identified from a craniofacial database search of patients with hemifacial microsomia and who were born to diabetic mothers. Thus, both groups were born to diabetic mothers and had hemifacial microsomia (67%), microtia (52%), hearing loss (43%), epibulbar dermoids (24%), and fused cervical vertebrae (24%). Therefore, the teratogenic effects of maternal diabetes probably include such craniofacial malformations as the oculoauriculovertebral/Goldenhar complex. Infants of diabetic mothers should be evaluated for craniofacial anomalies. Conversely, mothers of infants with craniofacial anomalies should be evaluated for diabetes to aid in counseling concerning cause and recurrence risks.

Retinal vein occlusion associated with methylenetetrahydrofolate reductase mutation

OBJECTIVE

To report on the occurrence of methylenetetrahydrofolate reductase (MTHFR) deficiency in patients with retinal vein occlusion (RVO).

DESIGN

Prospective case series

PARTICIPANTS

Fifty-nine consecutive patients with newly diagnosed RVO seen at the Retina Unit in the Tel Aviv Medical Center during 1997. METHODS/TESTING: Interviews and multiple blood analyses were done. Data were compared to the reported incidence of MTHFR deficiency in the Israeli population at large.

RESULTS

Twenty-six patients (44.1%) were heterozygotes and 11 (18.6%) were homozygotes for 677C-T mutation in MTHFR. The MTHFR 677C-T homozygosity was documented as being present in 10.4% of healthy individuals in the Israeli population. The difference in homozygosity was found to be statistically significant (P = 0.038).

CONCLUSIONS

Retinal vein occlusion may be associated with a mutation in MTHFR.

High-dose dexamethasone for splenectomy in patients with idiopathic thrombocytopenic purpura

High-dose intravenous immune globulin (IV IgG) is currently the treatment of choice for patients with idiopathic thrombocytopenic purpura (ITP) who undergo splenectomy; however, this treatment is extremely expensive. We report on 13 ITP patients with severe thrombocytopenia (<20 x 10(9)/l) who were prepared for laparoscopic splenectomy with a 4-day oral course of high-dose (40 mg/day) dexamethasone (DEX). Four patients had an excellent response with platelet counts that increased to above 150 x 10(9)/l. Seven patients had a good response with a platelet count that increased to between 50 and 150 x 10(9)/l (median 121 x 10(9)/l). Two patients were resistant both to DEX and IV IgG. The operation was uneventful in all the patients, including the 2 who had resistant ITP and were operated on while their platelet count was very low (5 x 10(9)/l). Thus, high-dose DEX, which is an easy, effective and inexpensive treatment, is recommended for the preparation of ITP patients prior to splenectomy.

High-dose intravenous gamma-globulins for heparin-induced thrombocytopenia: a prompt response

Heparin-induced thrombocytopenia (HIT) is a common drug induced autoimmune condition. The thrombocytopenia is caused in most cases by an antibody directed against the complex PF4/heparin. Recently, we have induced an experimental model of HIT by idiotypic manipulation. To confirm further the idiotypic involvement of HIT, we have treated successfully three patients with HIT with high-dose intravenous gamma-globulin (IVIG). Our three patients joint other two cases previously reported who were treated with IVIG and point to the efficacy of this type of therapy with minimal side effects. IVIG suppression of the anti-PF4/heparin autoantibody may support the idiotypic etiology of HIT.

The early cardiovascular toll of cigarette smoking in dyslipidaemic patients in the United Kingdom

Relationships between early cardiovascular risk at mean follow-up 1. 8 years and cigarette smoking status were investigated through analysis of data from participating clinics entered from 1981-1994 in the UK-Lipid Clinics Programme computerised database. Lipid profiles and new cardiovascular events were recorded for 3601 male, 4883 female human non-smokers mean age 44.7 and 53.1 years, 3077 male, 2275 female current smokers age 46.3 and 50.3 years and 7210 male, 4559 female age 49.2 and 53.3 years ever-smokers. Levels of triglycerides and total cholesterol increased across the gradient never/ex/current smoker, with a reverse gradient for HDL-cholesterol. Never-smokers were slightly lighter than other groups and males were younger, differences insufficient to explain the lipid variation. Minor differences in blood pressure between groups did not show this gradient and the development of new hypertension was not consistently related to smoking habits. In contrast the expression of newly-recorded cardiovascular disease was greater and in some categories doubled for current or ex-smokers in contrast with never-smokers. This survey emphasises first, the continuing inadequacy of stop-smoking support even at specialist clinics, second, that patients who give up smoking are to be congratulated and benefit in the long-term but third, that the change in status can be recent and classification as ex-smoker can conceal high short-term risk, for which lipid profiles may also be significant and justify priority attention in management.

Bilateral retinal vein occlusion associated with 5,10-methylenetetrahydrofolate reductase mutation

PURPOSE

To report on the occurrence of 5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency, known to cause mild to moderate hyperhomocystinemia and increased risk of vascular occlusive disease, in a young patient with bilateral central retinal vein occlusion.

METHODS

A 25-year-old man was initially examined with central retinal vein occlusion in the right eye, followed 4 months later by a central retinal vein occlusion in the left eye. Studies for risk factors predisposing to thrombosis were performed.

RESULTS

Hematologic studies failed to detect any pathology. However, the patient was found to be homozygous for 677C-T mutation in MTHFR enzyme.

CONCLUSION

Central retinal vein occlusion may be associated with a mutation in MTHFR.

The acute rise in plasma fibrinogen concentration with exercise is influenced by the G-453-A polymorphism of the beta-fibrinogen gene

We have investigated the effects of chronic physical training and acute intensive exercise on plasma fibrinogen levels and the relationship of these responses to beta-fibrinogen G-453-A polymorphism genotype. One hundred fifty-six male British Army recruits were studied at the start of their 10-week basic training, which emphasizes physical fitness. Cohorts were restudied between 0.5 and 5 days after a major 2-day strenuous military exercise (ME) undertaken in their final week of training. Changes in fibrinogen concentration were adjusted for the effects of age, body mass index, and smoking history. Compared with baseline values, fibrinogen concentrations were significantly lower (11.9%, P=.04) at day 5 after ME, consistent with the beneficial effect of training. However, they were higher on days 1 through 3 after ME (suggesting an "acute-phase" response to strenuous exercise) and were maximal on days 1 and 2 (27.2%, P<.001 and 37.1%, P<.001 respectively). Fibrinogen genotype was available in 149 individuals. As expected from previous studies, men with one or more fibrinogen gene A-453 alleles had plasma fibrinogen concentration slightly but significantly higher at baseline (4.5%, P=.11). During the acute-phase response (days 2 and 3), however, the degree of rise was strongly related to the presence of the A allele, being 26.7+/-5.4% (mean+/-SE), 36.5+/-11.0%, and 89.2+/-30.7 for the GG, GA, and AA genotypes, respectively (P=.01). These results confirm that chronic exercise training lowers plasma fibrinogen levels, that intensive exercise generates an acute-phase rise in levels, and that this acute response is strongly influenced by the G/A polymorphism of the beta-fibrinogen gene.

Increased adhesiveness of peripheral blood leukocytes corresponds to the appearance of expansion following anterior wall myocardial infarction

The appearance of increased leukocyte adhesiveness/aggregation as an inflammatory marker in the peripheral blood of patients with anterior wall myocardial infarction was monitored. Of the 26 patients included in the study, 7 had infarct expansion as shown by an enlargement of left ventricular end-diastolic volume. The percent of aggregated leukocytes in the peripheral blood of patients with expansion (29.7 +/- 15.5%) was significantly higher (p = 0.01) than that obtained from patients with no expansion (18.5 +/- 6.8%). The lack of significant differences in peak creatine kinase concentrations between patients with and without expansion suggests that infarct size is not necessarily the main determinant for the appearance of expansion; an increased inflammatory reaction could be a contributory factor.

Increase in leukocyte adhesiveness and aggregation with stress: a model of human congestive heart failure

Stress has a significant influence on the function of the human organism. A simple, rapid, inexpensive, and reliable marker for stress would therefore be of great value. We have recently noted that stress increases the state of leukocyte adhesiveness and aggregation in the peripheral blood. We evaluated 64 patients who had various degrees of congestive heart failure, a condition known to induce a state of physiologic stress, to verify whether a relation exists between the intensity of the stress response and the magnitude of leukocyte adhesiveness. Included in the 64 were 53 patients without congestive heart failure, 23 with compensated failure, 22 with significant congestive heart failure, and 19 with florid pulmonary edema. The percentage of aggregated leukocytes in these four group was 6% +/- 4%, 6% +/- 4%, 10.5% +/- 5%, and 15% +/- 14%. Values for the third and fourth group differed in a statistically significant way. Thus, with further investigation into additional stress-inducing conditions, the state of leukocyte adhesion and aggregation may prove to be a reliable marker for the detection of stress and an inexpensive tool for quantifying its severity.

Tyrosinase related protein 1 (TRP1) functions as a DHICA oxidase in melanin biosynthesis

Several genes critical to the enzymatic regulation of melanin production in mammals have recently been cloned and mapped to the albino, brown and slaty loci in mice. All three genes encode proteins with similar structures and features, but with distinct catalytic capacities; the functions of two of those gene products have previously been identified. The albino locus encodes tyrosinase, an enzyme with three distinct melanogenic functions, while the slaty locus encodes tyrosinase-related protein 2 (TRP2), an enzyme with a single specific, but distinct, function as DOPAchrome tautomerase. Although the brown locus, encoding TRP1, was actually the first member of the tyrosinase gene family to be cloned, its catalytic function (which results in the production of black rather than brown melanin) has been in general dispute. In this study we have used two different techniques (expression of TRP1 in transfected fibroblasts and immunoaffinity purification of TRP1 from melanocytes) to examine the enzymatic function(s) of TRP1. The data demonstrate that the specific melanogenic function of TRP1 is the oxidation of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) to a carboxylated indole-quinone at a down-stream point in the melanin biosynthetic pathway. This enzyme activity appears to be essential to the further metabolism of DHICA to a high molecular weight pigmented biopolymer.

DHICA oxidase activity of TRP1 and interactions with other melanogenic enzymes

Tyrosinase-related protein 1 (TRP1) maps to the brown locus in mice. Although the specific function of TRP1 has been in dispute, mutations in its structural gene result in the formation of brown rather than black melanin. We have investigated the melanogenic function of TRP1 by using immune-affinity purification of the protein and also by using transfection of its gene into fibroblasts to study its characteristics. We show that TRP1 has the ability to oxidize DHICA, a melanogenic intermediate derived from DOPAchrome. In addition, TRP1 has the ability to interact with tyrosinase and significantly stabilize the latter's catalytic function.

Lipoprotein lipase activity in patients with combined hyperlipidaemia

The aetiology of familial combined hyperlipidaemia remains obscure, with both genetic and environmental factors contributing to the phenotype, which is frequently associated with premature coronary heart disease. We have studied lipoprotein lipase (LPL) activity and hepatic lipase (HL) activity in patients with coronary heart disease to determine whether variation in lipase activities contributes to this phenotype. Forty-one patients (mean age 50 years; 30 male) were selected on the basis of cholesterol levels above 6.5 mmol/l and triglyceride levels above 2.2 mmol/l, with apoprotein B values over the 90th percentile. There was a family history of premature coronary heart disease in 78% and a personal history in 64%, at mean age 44, the patient group therefore predominantly corresponded to the common definition of familial combined hyperlipidaemia, appropriate in the absence of molecular markers. None of the patients was diabetic; hypertension and smoking were not over represented. Blood samples were taken following intravenous administration of heparin (100 IU/kg body wt), and LPL and HL activities were measured. Mean post-heparin LPL was significantly lower in patients than controls 10 min after heparin administration (2.98 +/- 1.04 and 3.86 +/- 0.93 mumol ml-1 h-1, respectively, P = 0.001), and 37% patients had values below the 10th percentile of controls. Both male and female patients had significantly higher HL activities than their respective controls at 5, 10, 20 and 30 minutes post-heparin. As expected, both female patients and controls had lower HL activities than males, although this sex difference did not reach statistical significance in the patient group.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of alpha-interferon on thymidine, uridine, and leucine uptake and ultrastructure of peripheral blood mononuclear cells from multiple myeloma patients

The effect of IFN alpha-2b on thymidine, uridine, and leucine uptake was examined on peripheral blood mononuclear cells (PBMC) of healthy donors and 15 patients with multiple myeloma (MM). In addition, the surface ultrastructure of the cells incubated without or with IFN alpha-2b was examined with a scanning electron microscope. The results showed that IFN had no effect on thymidine, uridine, or leucine uptake of unstimulated MM and control PBMC. On the other hand IFN inhibited thymidine, and uridine uptake of PWM-stimulated MM PBMC, but had no effect on healthy donor stimulated PBMC. IFN inhibited also thymidine and uridine uptake in PHA-stimulated healthy donors and MM patients' PBMC. The cellular surface ultrastructure of MM lymphocytes incubated with 100 u/ml IFN showed disappearance of the microvilli and formation of cellular pits, whereas in healthy donor lymphocytes IFN caused flattening of microvilli.

Treatment of systemic lupus erythematosus by prolonged administration of high dose intravenous immunoglobulin: report of 2 cases

Two patients with life threatening manifestations of systemic lupus erythematosus (SLE), unresponsive to corticosteroid and immunosuppressive therapy, were treated with high dose intravenous immunoglobulin (IVIG). Following IVIG therapy, lupus pneumonitis and encephalitis in the first patient, and lupus nephritis in the second patient, resolved. Continuous treatment with IVIG, every 4 weeks for up to 20 months induced a prolonged clinical and laboratory remission. Treatment with cytotoxic agents was stopped, and the dosage of corticosteroids lowered. Exacerbation of lupus nephritis occurred in the second patient after 10 months of IVIG therapy. We suggest that prolonged use of high dose IVIG may be a useful therapy for acute exacerbations of SLE and for inducing prolonged remissions.

A combined urodynamic and continence unit--a review of the first 19 years

We have completed a 19-year audit of all patients referred to the urodynamic/continence unit since its inception in 1972 and their subsequent clinical management; a total of 20,437 patients were referred, increasing from 51 in the first year to 1564 in 1990. Although the annual number of referrals has remained constant for the last 8 years, the need for more complex urodynamic assessment such as video-cystourethrography has increased from 5% (56/1164) in 1981 to 25% (385/1564) in 1990. The number of out-patient attendances to medical, physiotherapy and continence clinics has also increased over that period. We conclude that the number of referrals represents increasing recognition of the value of urodynamic assessment. Accurate diagnosis leads to more effective treatment, whether surgical, medical or conservative. Some methods of diagnosis are complex and suitable only for a tertiary referral centre.

Organising a continence advisory service

Modern surgical techniques have greatly improved the treatment of incontinence, but there remains a large number of patients for whom conservative management will be necessary. This paper reports the appointment of a continence adviser 10 years ago, and describes the subsequent development of a District Continence Advisory Service. Experience has shown that this appointment is essential, not only in terms of facilitating the service, but also as a means of ensuring cost efficiency.

Acetazolamide-responsive vestibulocerebellar syndrome: clinical and oculographic features

Five patients who presented with long-standing episodic vertigo had ocular motor signs localizing to the vestibulocerebellum. In each patient, the episodic vertigo was either abolished or markedly decreased in frequency and severity with acetazolamide therapy. In 4, other family members had identical symptoms and signs. This syndrome is 1 of the few treatable causes of chronic episodic vertigo.

The persistence of neutralizing antibodies after revaccination against smallpox

Persistence of neutralizing antibodies after revaccination against smallpox was studied. Single serum samples from 140 revaccinated donors were tested for neutralizing antibodies using the plaque reduction assay. The donors, aged 21-49 years at sampling, had been vaccinated in infancy and revaccinated at 8 and 18 years; they formed seven groups of 20 men each, revaccinated about 3, 5, 10, 15, 20, 25, and 30 years before sampling. The differences in mean titer among groups were insignificant (P greater than .01). The titer significantly decreased during the first 3 years after the revaccination but remained stable for at least 30 years thereafter (geometric mean titer, 10.5; 95% confidence interval, 6.8-16.4). The results suggest that there is probably no need for routine revaccinations beyond the primary and two revaccinations; nevertheless, persons at high risk should be revaccinated regardless of their vaccination status.