Post-Stroke Resting-State EEG Connectivity: A Longitudinal Neuro-Rehabilitation Study

Stroke is a leading cause of permanent disability worldwide. Even after adequate treatment, the majority of patients do not recover fully, making them dependent on others for carrying out Activities of Daily Living (ADL). An improved understanding of the underlying mechanism of plasticity will help us in customizing the translational approach for learning and rehabilitation following a stroke. For this study, a 2-minute resting state EEG data were recorded at 5 time-points for 3-months after stroke onset. Directed Transfer Function (DTF) was used to study neural reorganization for 3 months. DTF for different brain regions and sub-bands was correlated with FMA. The information flow was studied for different brain regions as well as Affected Region (AR). Occipital region showed good correlation (r = 0.45 to 0.47) with FMA. Contra-lesional and ipsi-lesional regions trajectories complement each other during acute and sub-acute phase. The information outflow vs inflow imbalance of AR was restored by the end of 3 months. DTF can be used as biomarker for studying neuroplasticity. Occipital, temporal and motor cortex regions play an important role during neuro-rehabilitation. The information about different regions during rehabilitation will help us in designing subject-specific interventions for better recovery.

Wavelet and Region-Specific EEG Signal Analysis for Studying Post-Stroke Rehabilitation

Post-stroke monitoring is a crucial step for properly studying the progress of stroke patients. The rehabilitation process consists of exercise regimes that help in constantly engaging the affected part of the brain leading to faster recovery. The work here studies the effectiveness of the rehabilitation regime by investigating several parameters that can play important role in observing the immediate effect of the exercises. Various parameters from different wavelet coefficients were extracted for monitoring rehabilitation for up to 90 days. Energy and waveform length show maximum variation when monitoring pre and post-exercise changes. The parameters were correlated with clinical(FMA) score. Centroid Index gave high correlation value for beta band (r = -0.559). Alpha band on the other hand showed a good correlation with all the extracted fe atures, maximum being -0.6988 with energy. So for monitoring post-stroke rehabilitation alpha and beta bands should be focused. Region-specific analyses were also done to monitor changes in different parts of the brain.

Cost-effectiveness of mifepristone and misoprostol versus misoprostol alone for the management of missed miscarriage: an economic evaluation based on the MifeMiso trial

OBJECTIVE

To assess the cost-effectiveness of mifepristone and misoprostol (MifeMiso) compared with misoprostol only for the medical management of a missed miscarriage.

DESIGN

Within-trial economic evaluation and model-based analysis to set the findings in the context of the wider economic evidence for a range of comparators. Incremental costs and outcomes were calculated using nonparametric bootstrapping and reported using cost-effectiveness acceptability curves. Analyses were performed from the perspective of the UK's National Health Service (NHS).

SETTING

Twenty-eight UK NHS early pregnancy units.

SAMPLE

A cohort of 711 women aged 16-39 years with ultrasound evidence of a missed miscarriage.

METHODS

Treatment with mifepristone and misoprostol or with matched placebo and misoprostol tablets.

MAIN OUTCOME MEASURES

Cost per additional successfully managed miscarriage and quality-adjusted life years (QALYs).

RESULTS

For the within-trial analysis, MifeMiso intervention resulted in an absolute effect difference of 6.6% (95% CI 0.7-12.5%) per successfully managed miscarriage and a QALYs difference of 0.04% (95% CI -0.01 to 0.1%). The average cost per successfully managed miscarriage was lower in the MifeMiso arm than in the placebo and misoprostol arm, with a cost saving of £182 (95% CI £26-£338). Hence, the MifeMiso intervention dominated the use of misoprostol alone. The model-based analysis showed that the MifeMiso intervention is preferable, compared with expectant management, and this is the current medical management strategy. However, the model-based evidence suggests that the intervention is a less effective but less costly strategy than surgical management.

CONCLUSIONS

The within-trial analysis found that based on cost-effectiveness grounds, the MifeMiso intervention is likely to be recommended by decision makers for the medical management of women presenting with a missed miscarriage.

TWEETABLE ABSTRACT

The combination of mifepristone and misoprostol is more effective and less costly than misoprostol alone for the management of missed miscarriages.

The Current and Future Challenges of Hip Fracture Management in Malaysia

By 2050, it is predicted that six million hip fractures will occur each year of which the majority will happen in Asia. Malaysia is not spared from this predicted rise and its rate of increase will be one of the highest in this region. Much of this is driven by our unprecedented growth in the number of older people. Characteristics of individuals with hip fractures in Malaysia mirror what has been reported in other countries. They will be older multimorbid people who were already at risk of falls and fractures. Outcomes were poor with at least a quarter do not survive beyond 12 months and in those that do survive have limitation in their mobility and activities of daily living. Reviewing how these fractures are managed and incorporating new models of care, such as orthogeriatric care, could address these poor outcomes. Experts have warned of the devastating impact of hip fracture in Malaysia and that prompt action is urgently required. Despite that, there remains no national agenda to highlight the need to improve musculoskeletal health in the country.

Basal Cell Adenoma of the Parotid Gland

Basal Cell Adenoma (BCA) known as monomorphic adenoma is a rare type of benign epithelial salivary neoplasm that mostly occurs in the parotid gland. Clinically BCA appears as a firm, mobile, slow-growing mass and is usually diagnosed during the histopathological examination of the resected surgical specimen. Histological differential diagnosis ranges from benign to malignant neoplasms such as pleomorphic adenoma, basal cell adenocarcinoma, adenoid cystic carcinoma and basaloid squamous cell carcinoma. The treatment of BCA is surgical excision, due to its varied prognosis with the different histological subtypes; a regular long term follow up of the patient postoperatively is mandatory. We report a rare and interesting case of basal cell adenoma of the parotid gland in a 52 year old female. We review the literature; discuss the diagnosis and management of this rare histological entity.

An Unusual Cause of Chylothorax after Esophagectomy

Chylothorax due to inadvertent thoracic duct injury after esophagectomy is a well-known complication and requires careful postoperative management and timely intervention to prevent potential morbidity and mortality. We present a case of high-output chylothorax after esophagectomy where the source of chyle leak was not in the thorax.

Accelerated surgery versus standard care in hip fracture (HIP ATTACK): an international, randomised, controlled trial

BACKGROUND

Observational studies have suggested that accelerated surgery is associated with improved outcomes in patients with a hip fracture. The HIP ATTACK trial assessed whether accelerated surgery could reduce mortality and major complications.

METHODS

HIP ATTACK was an international, randomised, controlled trial done at 69 hospitals in 17 countries. Patients with a hip fracture that required surgery and were aged 45 years or older were eligible. Research personnel randomly assigned patients (1:1) through a central computerised randomisation system using randomly varying block sizes to either accelerated surgery (goal of surgery within 6 h of diagnosis) or standard care. The coprimary outcomes were mortality and a composite of major complications (ie, mortality and non-fatal myocardial infarction, stroke, venous thromboembolism, sepsis, pneumonia, life-threatening bleeding, and major bleeding) at 90 days after randomisation. Patients, health-care providers, and study staff were aware of treatment assignment, but outcome adjudicators were masked to treatment allocation. Patients were analysed according to the intention-to-treat principle. This study is registered at ClinicalTrials.gov (NCT02027896).

FINDINGS

Between March 14, 2014, and May 24, 2019, 27 701 patients were screened, of whom 7780 were eligible. 2970 of these were enrolled and randomly assigned to receive accelerated surgery (n=1487) or standard care (n=1483). The median time from hip fracture diagnosis to surgery was 6 h (IQR 4-9) in the accelerated-surgery group and 24 h (10-42) in the standard-care group (p<0·0001). 140 (9%) patients assigned to accelerated surgery and 154 (10%) assigned to standard care died, with a hazard ratio (HR) of 0·91 (95% CI 0·72 to 1·14) and absolute risk reduction (ARR) of 1% (-1 to 3; p=0·40). Major complications occurred in 321 (22%) patients assigned to accelerated surgery and 331 (22%) assigned to standard care, with an HR of 0·97 (0·83 to 1·13) and an ARR of 1% (-2 to 4; p=0·71).

INTERPRETATION

Among patients with a hip fracture, accelerated surgery did not significantly lower the risk of mortality or a composite of major complications compared with standard care.

FUNDING

Canadian Institutes of Health Research.

Upper Limb Prosthesis Control: A Hybrid EEG-EMG Scheme for Motion Estimation in Transhumeral Subjects

This study described the use of Kernel Least Square Tracker based estimation for 3-dimensional shoulder, elbow motion kinematics from surface Electromyogram (EMG) and a two-stage multiclass Support Vector Machine based classification of different wrist, grip and finger motions from Electroencephalogram (EEG). The advantage of employing hybrid EEG-EMG strategy for upper limb motion estimation was demonstrated for a transhumeral subject. The method utilized EMG from upper arm muscles for elbow motion (and shoulder motion in case of higher degree amputation scenario) and used EEG for discerning basic wrist, grip and finger motions. The results showed that the hybrid scheme could estimate shoulder, elbow motion with more than 90% accuracy and wrist, grip and finger motion with 65%-70% accuracy. This strategy of using hybrid EEG-EMG motion estimation, thus, could be employed in developing a more intuitive upper limb prosthesis controller with multiple degrees of freedom.

A fingertip force prediction model for grasp patterns characterised from the chaotic behaviour of EEG

A stable grasp is attained through appropriate hand preshaping and precise fingertip forces. Here, we have proposed a method to decode grasp patterns from motor imagery and subsequent fingertip force estimation model with a slippage avoidance strategy. We have developed a feature-based classification of electroencephalography (EEG) associated with imagination of the grasping postures. Chaotic behaviour of EEG for different grasping patterns has been utilised to capture the dynamics of associated motor activities. We have computed correlation dimension (CD) as the feature and classified with "one against one" multiclass support vector machine (SVM) to discriminate between different grasping patterns. The result of the analysis showed varying classification accuracies at different subband levels. Broad categories of grasping patterns, namely, power grasp and precision grasp, were classified at a 96.0% accuracy rate in the alpha subband. Furthermore, power grasp subtypes were classified with an accuracy of 97.2% in the upper beta subband, whereas precision grasp subtypes showed relatively lower 75.0% accuracy in the alpha subband. Following assessment of fingertip force distributions while grasping, a nonlinear autoregressive (NAR) model with proper prediction of fingertip forces was proposed for each grasp pattern. A slippage detection strategy has been incorporated with automatic recalibration of the regripping force. Intention of each grasp pattern associated with corresponding fingertip force model was virtualised in this work. This integrated system can be utilised as the control strategy for prosthetic hand in the future. The model to virtualise motor imagery based fingertip force prediction with inherent slippage correction for different grasp types ᅟ.

Fifth metatarsal fractures - Is routine follow-up necessary?

BACKGROUND

Fifth metatarsal fractures are common, and the outcome with conservative treatment is generally very satisfactory. Operative treatment is only used for selected injuries, particularly stress fractures. Traditionally these patients are routinely reviewed at a fracture clinic, mainly due to the perceived risk of non-union with a Jones' fracture. In 2011 we introduced a standardised protocol to promote weight bearing as pain allowed with an elasticated support or a removable boot. Patients were discharged with structured advice and a help-line number to access care if required, but no further face-to-face review was arranged. More complex cases were reviewed at a "virtual clinic." Our hypothesis was that the introduction of this standardised protocol would be safe, patient-centred and significantly reduce unnecessary outpatient clinic review.

PATIENTS AND METHODS

We audited fracture clinic attendance and outcomes 1 year before and 1 year after the protocol was introduced in 2011. All radiographs taken at the Emergency Department (ED) presentation were reviewed and classified independently for validation.

RESULTS

From 2009 to 2010, 279 patients who presented to the ED with fifth metatarsal fractures were referred to a fracture clinic. Of these 279 patients, 267 (96%) attended the fracture clinic, resulting in an overall total of 491 outpatient attendances. Three (1%) were treated operatively for delayed/non-union. From 2011 to 2012, 339 patients presented to the ED with fifth metatarsal fractures - only 67 (20%) were referred to a fracture clinic. 62 (18%) attended clinic appointments with 102 appointments in total. Five (1%) required operative intervention.

CONCLUSION

Our study showed no added clinical value for routine outpatient follow-up of fifth metatarsal fractures. Patients can be safely discharged and allowed to bear weight at the time of initial ED presentation if they are provided with appropriate information and ready access to experienced fracture clinic staff.

Case report: fibrous dysplasia of the navicular bone treated with excision of navicular and talo-cuneiform arthrodesis

Fibrous dysplasia is an uncommon beningn disorder of bone. It usually affects the long bones, and is uncommon in the navicular. We describe a case of fibrous dysplasia of the navicular successfully treated with navicular excision and talo-cuneiform arthrodesis.

Safety and efficacy of forefoot surgery under ankle block anaesthesia

BACKGROUND

Ankle block as the sole anaesthetic for forefoot surgery is not used uniformly throughout the UK despite obvious advantages and widespread use internationally.

AIM

Evaluation of safety and effectiveness of performing elective forefoot surgery under ankle block anaesthesia alone in a pilot cohort of patients in a Scottish unit.

METHODS

Data were collected from 81 consecutive forefoot procedures (71 patients) using a standardised questionnaire including incremental pain assessment (0-10; 0 no pain, 10 severe pain).

RESULTS

Seven patients reported pain during surgery; average score 0.17. Average pain scores 6, 12, 24 and 48 h following surgery were 1.5, 3.09, 2.3 and 1.9, respectively. All patients were discharged home and walking on the same day.

CONCLUSION

Forefoot surgery under ankle block alone may be safe and effective. Anaesthesia obtained permitted routine forefoot procedures and provided lasting post-operative analgesia. Combined with intra-operative sedation, use of ankle tourniquet and same day discharge, it had very high patient acceptance and satisfaction.

Isolated plantar dislocation of the 1st metatarsophalangeal joint

Plantar dislocation of the 1st metatarsophalangeal joint is an extremely rare injury. To the best of our knowledge, there are no previous reports in the literature of an isolated dislocation of this type requiring open reduction and surgical repair. In this case report, we describe the clinical and operative findings and discuss in detail our surgical technique for the successful management of this unusual injury.

Emergency brake response time after first metatarsal osteotomy

BACKGROUND

There is sparse information upon which to recommend a return to activity after foot surgery. The purpose of this study was to determine whether six weeks is sufficient time for the emergency brake response time to return to preoperative levels after a first metatarsal osteotomy for symptomatic hallux valgus.

METHODS

We conducted a prospective, observational study to assess the effect of surgery on emergency brake response time in a group of twenty-eight patients undergoing a unilateral first metatarsal osteotomy on the right side for symptomatic hallux valgus. A custom-made driving simulator was used to assess total brake response time, reaction time, and brake time. Patients were assessed preoperatively and at two and six weeks postoperatively. A control group of twenty-eight individuals matched for age, driving status, and sex was included for baseline comparison.

RESULTS

Total brake response time, reaction time, and brake time were significantly lower for the control cohort compared with the preoperative values recorded in the study cohort (p < 0.05). Only seven of the twenty-eight study patients were able to complete the assessment at two weeks; the remainder were not able to complete it because of postoperative pain. All patients were able to comfortably complete the study at six weeks. In the study cohort, the total brake response time, reaction time, and brake time had significantly improved compared with preoperative recordings (p < 0.05).

CONCLUSIONS

By six weeks after surgery, emergency braking time in patients undergoing a first metatarsal osteotomy is similar to that of healthy individuals.

The differential diagnosis of foot lumps: 101 cases treated surgically in North Glasgow over 4 years

INTRODUCTION

There are a wide variety of different lesions which present as lumps of the foot. There have been very few studies which look at the presenting characteristics or the differential diagnosis of such lesions.

PATIENTS AND METHODS

All patients who underwent excision or biopsy of a foot lump over a period of 4 years were studied in order to determine patient demographics, presenting characteristics, diagnoses encountered and to assess the diagnostic accuracy of the surgeon.

RESULTS

In total, 101 patients were identified. Average age was 47.3 years (range, 14-79 years); there was a marked female preponderance with 73 females and 28 males. Thirty different histological types were identified; ganglion cysts were the most commonly encountered lesions and there was only one malignant lesion encountered in this study. Only 58 out of the 101 lumps were correctly diagnosed prior to surgery. Certain lesions were more commonly encountered in specific zones of the foot.

CONCLUSIONS

We have shown that there are a wide variety of potential diagnoses which have to be considered when examining a patient with a foot lump. There is a low diagnostic accuracy for foot lumps and, therefore, surgical excision and histological diagnosis should be sought if there is any uncertainty.

Effect of quercetin on galactose-induced hyperglycaemic oxidative stress in hepatic and neuronal tissues of Wistar rats

In recent times there has been great demand for natural products that have possible preventive action against diabetes and its secondary complications. Keeping this in mind, this study was undertaken to investigate the influence of the flavonoid, quercetin, on oxidative stress markers and the antioxidant defence system of hepatic and neuronal tissues from galactose-induced hyperglycaemic rats. Weanling male Wistar rats were treated with 30% galactose in AIN 93 diet (group B, n=8) to induce hyperglycaemia. Control rats received normal Stock AIN 93 diet (group A, n=8). The third set of rats received group B diet with quercetin at 400 mg/100 g diet (group C, n=8). Glucose levels and body weights were measured on a weekly basis for four weeks to monitor the hyperglycaemia induced by galactose feeding. Parameters involved in the pathogenesis of galactose-induced hyperglycaemia, which included organosomatic index, protein content, antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), tryptophan fluorescence, content of protein carbonyls, prooxidant malonaldehyde (MDA) and glutathione (GSH) in hepatic and neuronal tissues were determined at the end of the fourth week. The study suggest that quercetin counters the pro-oxidant effects of galactose-induced hyperglycaemic stress, as there was a significant reversal of changes with respect to body weights, organosomatic index of hepatic and neuronal tissues, lipid peroxidation, protein carbonyl content, reduced glutathione and activities of antioxidant enzymes. In addition, treatment with quercetin appears to reduce the osmotic stress induced by hyperglycaemia, as assessed by polyol pathway enzyme aldose reductase. These results imply that inclusion of quercetin in the diet controls, to some extent, galactose-induced hyperglycaemia and its attendant complications.

Ectopic expression of rice OsMADS1 reveals a role in specifying the lemma and palea, grass floral organs analogous to sepals

MADS-domain-containing transcription factors play diverse roles in plant development. The prototypic members of this gene family are the floral organ identity genes of the model dicotyledonous plant, Arabidopsis thaliana. Sequence relatedness and function ascribe them to AP1/AGL9, AG, AP3 and PI gene groups. The rice MADS-box gene, OsMADS1, is a member of the AP1/ AGL9 sub-group. Tomato and Petunia members of this sub-group specify floral meristem identity and control organ development in three inner whorls. Reported here are phylogenetic analyses that show OsMADS1 to form a distinct clade within the AGL9 gene family. This sub-group currently has only three other monocot genes. We have studied the expression pattern of OsMADS1 and determined the consequences of its ectopic expression in transgenic rice plants. OsMADS1 is not expressed during panicle branching; earliest expression is in spikelet meristems where it is excluded from the outer rudimentary/sterile glumes. During organogenesis, OsMADS1 expression is confined to the lemma and palea, with weak expression in the carpel. Ectopic OsMADS1 expression results in stunted panicles with irregularly positioned branches and spikelets. Additionally, in spikelets, the outer rudimentary glumes are transformed to lemma/palea-like organs. Together, these data suggest a distinct role for OsMADS1 and its monocot relatives in assigning lemma/palea identity.

SB-205384: a GABA(A) receptor modulator with novel mechanism of action that shows subunit selectivity

1. SB-205384, and its (+) enantiomer (+)-SB-205384 were tested for their modulatory effects on human GABA(A) receptor subunit combinations expressed in Xenopus oocytes by electrophysiological methods. 2. The slowing of the decay rate induced by SB-205384 on native GABA-activated currents in rat neurones was also seen on GABA(A) currents in oocytes expressing human GABA(A) subunits. This temporal effect was observed for the alpha3beta2gamma2 subunit combination with little effect in subunit combinations containing either alpha1 or alpha2. 3. Potentiation of the peak amplitude of the GABA-activated currents by SB-205384 or (+)-SB-205384 was less specific for a particular subunit combination, although the greatest effect at 10 microM drug was seen on the alpha3beta2gamma2 subunit combination. 4. In contrast, zolpidem, a benzodiazepine site modulator, did not significantly slow decay rates of GABA(A) currents in oocytes expressing the alpha3beta2gamma2 subunit combination. Zolpidem, as expected, did selectively potentiate GABA-activated currents on oocytes expressing the gamma2 subunit compared to those containing the gamma1. 5. The results show that the novel kinetic modulatory profile of SB-205384 is selective for the alpha3beta2gamma2 subunit combination. This suggests that the compound is binding to a novel regulatory site on the subunit complex.

Cloning and characterization of a novel integrin beta3 subunit

We have identified a novel integrin beta3 subunit, termed beta3C, from a human osteoclast cDNA library. The COOH-terminal sequence and 3'-untranslated region of the beta3C subunit differs from the previously reported beta3A (platelet) and beta3B (placenta) sequences, while the regions coding for the transmembrane and extracellular domains are identical. The beta3C cytoplasmic domain contains 37 amino acids, the last 17 of which are encoded by a novel exon located about 6 kilobase pairs downstream of exon 14 of the beta3A gene. HEK 293 cells were stably co-transfected with alphaV and either beta3C (HEKbeta3C) or beta3A (HEKbeta3A). The viability of HEKbeta3C cells was lower than that of HEKbeta3A cells, and HEKbeta3C cells in culture grew as clusters rather than as a monolayer. The novel cytoplasmic domain did not affect receptor binding affinity; both alphaVbeta3A and alphaVbeta3C isoforms exhibited high affinity binding to 125I-echistatin and cyclic and linear RGD peptides. However, in contrast to HEKbeta3A, HEKbeta3C cells failed to adhere to osteopontin, an alphaVbeta3 matrix protein. The data provide further support for the key role of the cytoplasmic domain of the beta3 integrin in cell adhesion and suggest a potential role for the beta3C integrin subunit in modulating cell-matrix interactions.

Genetic marker profile of primitive Kutia Kondh tribal population of Phulbani district (Orissa)

Blood samples from 330 Kutia Kondhs (a primitive tribal population of Orissa) were subjected to a battery of tests for genetic markers to find out the incidence of various blood group polymorphisms (ABO, MN, Duffy, JKa), serum proteins, sickling and G-6-PD deficiency. Predominance of O (39.09%) blood group for ABO, N blood group (53.44) for MN and Fya+b+ (55.72) for Duffy blood group, were observed. High incidence of Hp2-1 (39.33), SS (70.43) and CC (96.65) for haptoglobulin, C3 and transferrin respectively were seen. The overall frequency of sickling was observed to be 16.36 per cent. The sex-wise distribution of G-6-PD was 13.71 per cent for males and 1.84 for females.

Lysine 182 of endothelin B receptor modulates agonist selectivity and antagonist affinity: evidence for the overlap of peptide and non-peptide ligand binding sites

The potent vasoactive peptide hormone endothelin (ET) binds to receptors which belong to the G-protein coupled receptor family. The availability of non-peptide antagonists for ET receptors allows investigation of the relationship among the binding sites for peptide and non-peptide ligands. In this study, a lysine residue, conserved within transmembrane domain 3 (TM3) of the ETA and ETB receptor subtypes, is implicated in agonist and antagonist binding by its analogous position within TM3 to a binding site aspartate residue conserved within bioactive amine receptors. Replacement of this lysine within hETB by arginine, alanine, methionine, aspartate, or glutamate results in hETB variants with unaltered affinities for agonist peptide ET-1 but which have affinities for peptide agonists ET-2, ET-3, sarafotoxin 6C, and TRL 1736 which are between 1-3 orders of magnitude lower than their corresponding wild-type hETB values. Significantly, the affinities of non-peptide antagonists, (+/-)-SB 209670 and its analogs as well as Ro 46-2005, are abrogated. The results suggest that an interaction of K182 of hETB with the indan 2-carboxyl of (+/-)-SB 209670 may contribute to the high-affinity binding of the diarylindan antagonists. The results indicate that TM3 of hETB is a region of overlap among the binding sites of non-peptide antagonists and the affected peptide agonists.

Novel endothelin receptors in the follicular membranes of Xenopus laevis oocytes mediate calcium responses by signal transduction through gap junctions

Follicular oocytes from Xenopus laevis display saturable and high affinity endothelin (ET)-1 binding sites. Competition binding experiments using unlabeled ET-1, ET-3, and sarafotoxin 6c indicated that these ET receptors belong to the ETA receptor subtype. However, the ETA receptor-selective antagonist BQ123 [cyclo(D-Trp,D-Asp,L-Pro,D-Val,L-Leu)] failed to inhibit 125I-ET-1 binding to these receptors, suggesting that these receptors belong to a novel subtype of ETA receptors (ETAX) distinct from the human ETA receptors. These endogenous receptors are present in the follicular layer, because defolliculated oocytes did not show any 125I-ET-1 binding. Addition of ET-1 to follicular oocytes led to Ca2+ mobilization, which was reversibly blocked by treatments that uncouple gap junctions, suggesting that these ETAX receptors mediate their response by transferring signals through gap junctions. On the other hand, the expressed human ETA receptor-mediated Ca2+ mobilization was not blocked by inhibitors of gap junctions. In agreement with the binding data, the endogenous ETAX receptor-mediated response was not inhibited by BQ123 even at 100 nM, whereas the expressed human ETA receptor-mediated response was inhibited by 50% at concentrations as low as 10 nM. This further confirms that the amphibian ETAX receptors are different from mammalian ETA receptors. Finally, ET-1 enhanced the rate of progesterone-induced maturation of follicular oocytes, implying the involvement of these endogenous ETAX receptors in an in vivo maturation process.

Molecular characterization and regulation of the human endothelin receptors

Endothelin receptors (ETRs) are distributed throughout a variety of tissues. Two human cDNAs were identified which encode distinct ETR proteins. One cDNA encoded a 427-amino acid protein that shared 91% identity to rat ETAR. The second cDNA encoded a 442-amino acid protein that was 88% identical to rat ETBR. Ligand binding studies of the cloned receptors expressed in COS cells confirmed that they were pharmacologically ETAR and ETBR subtypes; although the selective antagonist BQ123 showed a potency similar to ET-3 in displacing 125I-ET-1 binding to ETAR. This observation contrasts with rat ETAR pharmacology where BQ123 has a 100-fold higher affinity than ET3. Chinese hamster ovary cells expressing the human ETAR displayed equal potencies in displacing 125I-ET-1 binding, which indicates that rat and human ETAR are pharmacologically distinct. Electrophysiological studies of both ETRs expressed in Xenopus oocytes revealed that they are functional. Northern analysis indicated that the two ETRs are differentially expressed in many tissues. Marmosets maintained on a high fat/high cholesterol diet exhibited 3-fold increase in ETBR mRNA levels with little change in ETAR mRNA levels. Availability of cDNA clones for ETR subtypes can open avenues for future analysis of their role in pathophysiology of various diseases.

Molecular cloning and characterization of the major endothelin receptor subtype in porcine cerebellum

Endothelin receptors (ETRs) display subtype heterogeneity and are widely distributed throughout the tissues of the periphery and central nervous system. In order to gain further insight into the potential molecular differences of ETRs, we initiated molecular cloning of ETR genes by screening for the appearance of 125I-ET-1 binding activity in COS cells transfected with pools of a porcine cerebellum cDNA expression library. Two independent clones (pPCETR 1.1 and pPCETR 5.6) were identified and isolated by repeated rounds of pool enrichment and COS cell expression. DNA sequence analysis of pPCET 1.1 and pPCET 5.6 indicated that both clones have the same nucleotide sequence; the deduced amino acid sequence indicated that the porcine cerebellum ETR is 443 residues in length and consists of seven potential transmembrane domains, with homology to members of the GTP-binding protein-coupled receptor superfamily. Northern analysis indicated a single mRNA species of about 5 kilobases, which is expressed significantly in cerebellum, lung, kidney, and pituitary. Expression of functional receptor was demonstrated by endothelin-1 (ET-1)-mediated Ca2+ mobilization in COS cells transfected with pPCETR 1.1 (COS/ETR 1.1) and ET-1-mediated electrophysiological responses in Xenopus oocytes injected with RNA derived from pPCETR 1.1. Quantitative comparison of saturation binding of 125I-ET-1 to either porcine cerebellum or COS/ETR 1.1 membranes indicated an identical apparent dissociation constant. The relative efficacy of ET-related peptides to compete for binding of 125I-ET-1 to receptor from porcine cerebellum and COS/ETR 1.1 indicated that both preparations encode a nonselective or ETBR subtype. Chemical cross-linking of 125I-ET-1 to receptor derived from cerebellum or COS/ETR 1 revealed two bands, with apparent molecular masses of 47 and 35 kDa. These data demonstrate that the pPCETR 1.1 encodes the major ETR subtype in the porcine cerebellum.

Chimeric interferon-gamma receptors demonstrate that an accessory factor required for activity interacts with the extracellular domain

We determined the species specificity and function of structural domains of the interferon-gamma receptor (IFN-gamma R) by construction of human/murine chimeric IFN-gamma R cDNA clones and their expression in various cells. We demonstrate that we can reconstitute a biologically active IFN-gamma R in eukaryotic cells with chimeric receptors as long as the extracellular domain and an accessory factor are from the same species. These results indicate that the extracellular domain of the receptor interacts directly or indirectly with the species-specific accessory factor.

Expression and reconstitution of a biologically active mouse interferon gamma receptor in hamster cells. Chromosomal location of an accessory factor

In order to localize the chromosome encoding the accessory factor required for function of the murine interferon gamma (IFN-gamma) receptor, we transfected a cDNA expression vector encoding the receptor into several Chinese hamster x mouse somatic cell hybrids. As mouse Chromosome 10 carries the gene which encodes the interferon gamma-receptor (Ifgr), we used somatic cell hybrids that lack this chromosome. The presence of mouse Chromosome 16 was required to generate a response to murine IFN-gamma as assayed by stimulation of class I major histocompatibility complex antigen expression. These results demonstrate a species-specific accessory factor encoded on mouse Chromosome 16 (termed Ifgt) is necessary for mouse IFN-gamma to stimulate major histocompatibility complex expression through its receptor.

Molecular genetic markers spanning mouse chromosome 10

Somatic cell hybrids, recombinant inbred (RI) strains, and progeny of an intersubspecific backcross were typed by Southern blot analysis to prepare a linkage map of mouse chromosome 10. The seven genetic markers in this map, four of which had not previously been positioned, include genes involved in oncogenesis (Gli, Myb, Tra-1), proviral integration (Emv-25), and immune responses (Ifg, Ifgr, Pfp). The linkage map spans much of the chromosome and covers a region of the mouse genome with few molecular markers. The gene order established here demonstrates that the genes for murine interferon-gamma (Ifg) and its receptor (Ifgr) are at opposite ends of the chromosome and that Ifgr and the Myb oncogene are closely linked, a factor that may be related to their joint transcriptional enhancement in some plasmacytoid lymphosarcomas.

Expression and reconstitution of a biologically active human interferon-gamma receptor in hamster cells

We report the expression of the human interferon-gamma (Hu-IFN-gamma) receptor from a cDNA clone in an animal cell where both stable expression of the cloned receptor as well as its biological activity is demonstrated for the first time. Biological activity of the receptor (i.e. expression of surface histocompatibility antigens in response to human interferon-gamma) requires the presence of human chromosome 21 demonstrating the requirement for at least one other species-specific factor in the modulation of receptor action. This system should now facilitate delineation of regions involved in the binding of human interferon-gamma and receptor signal transduction.

Molecular characterization of the murine interferon gamma receptor cDNA

Interferon gamma receptors (IFN-gamma R) exhibit remarkable species specificity. In order to understand the basis for this phenomenon, we have isolated a recombinant cDNA clone corresponding to the mouse (Mu) IFN-gamma R. Microinjection of the mRNA synthesized in vitro corresponding to the cloned cDNA into Xenopus laevis oocytes resulted in the synthesis of a protein that specifically binds Mu-IFN-gamma. Analysis of murine genomic and RNA blots with the cDNA probe indicates the presence of a single gene and a single mRNA species of about 2300 bases. Sequence analysis of the cDNA encoding the Mu-IFN-gamma R and comparison with the corresponding human IFN-gamma R sequence shows about 68% conservation of the extracellular domains and 51% conservation of the cytoplasmic domains at the nucleotide level. The results indicate that, as expected, the sequence of the receptor confers species specificity for the binding of IFN-gamma to the cell surface receptor. Moreover, it was previously shown that a human factor is required in addition to the receptor for the human IFN-gamma to function in hamster or mouse cells (Jung, V., Rashidbaigi, A., Jones, C., Tischfield, J.A., Shows, T.B., and Pestka, S. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 4151-4155). These results suggest an explanation for the second species-specific event required for function of the human receptor in mouse or hamster cells in that the intracellular domains are significantly different and thus cannot interact with the corresponding heterologous factor.

Expression of the murine interferon gamma receptor in Xenopus laevis oocytes

This study describes the isolation of mRNA for the murine interferon gamma receptor and its expression in frog oocytes. The binding properties and apparent molecular weight of the murine interferon gamma receptor protein synthesized in frog oocytes is similar to that found on mouse cells. This is the first report of a functional receptor for a polypeptide ligand (interferon gamma) expressed in and directly assayed on frog oocytes.