411 Mesenchymal Stem Cells for Shoulder Tendon Injury and Osteoarthritis

Introduction

In recent years there has been a boom in the advancements and research in mesenchymal stem cells (MSCs) injections for tissue regeneration. This has led to commercial products and early adoption of the technology. High profile cases, media and internet prominence of stem cell therapies have led to a patient demand for the treatment for numerous traumatic and degenerative musculoskeletal conditions.

Aim

In this article we aim to review the evidence for mesenchymal stem cell therapy so far, focusing on its use in osteoarthritis and specifically tendon repair within the shoulder.

Method

Through the database PubMed, the search included all animal models and clinical trials assessing the use of mesenchymal stem cells for treatment of osteoarthritis or rotator cuff pathology, up to the year 2018.

Results

We identified 20 animal studies (95% positive findings) and 17 human studies (94% positive findings) for Osteoarthritis (OA) (399 patients assessed), however all therapy was targeted at the knee. Rotator cuff tear studies yielded 8 animal studies findings and 3 human studies (100% positive findings in both) (106 patients assessed).

Conclusions

There is a reasonable body of evidence to support its use for the early stages of OA and as such phase III trials should be implicated. Evidence to support use of MSCs for rotator cuff tendon pathology is still in early stages with variable significance, but promising. More trials need to be done to assess its efficacy for injection both at the point of surgical repair and in non-surgical patients.

Current practice patterns for initial umbilical hernia repair in the United States

PURPOSE

The approach to repairing an initial umbilical hernia (IUH) varies substantially, and this likely depends on hernia size, patient age, sex, BMI, comorbidities including diabetes mellitus, and surgeon preference. Of these, only hernia size has been widely studied. This cross-sectional study aims to look at the practice pattern of umbilical hernia repair in the United States.

METHODS

A retrospective study was performed using data from the America Hernia Society Quality Collaborative. Patient characteristics included age, sex, hernia width, BMI, smoking status, and diabetes. Outcomes were use of mesh for repair, as well as surgical approach (open vs minimally invasive). Multivariate logistic regression was performed to assess the independent effect of age, sex, hernia width, BMI, smoking status, and diabetes on use of mesh and approach to repair.

RESULTS

3475 patients were included. 74% were men. Mesh use was more common in men (67% vs 60%, P < 0.001). Mesh was used in 33% of repairs ≤ 1 cm, and 82% of repairs > 1 cm (P < 0.001). Younger patients were less likely to receive a mesh repair (54% if age ≤ 35 vs 67% for age > 35, P < 0.001). However, on multivariate analysis, mesh use was associated with increasing hernia width (OR 5.474, 95% CI 4.7-6.3) as well as BMI (OR 1.8, 95% CI 1.5-2.1) but not with age or sex.

CONCLUSION

The majority of IUH are performed open. Patient BMI and hernia defect size contribute to choice of surgical technique including use of mesh. The use of mesh in 33% of hernias below 1 cm demonstrates a gap between evidence and practice. Patient factors including patient age and sex had no impact on operative approach or use of mesh.

The Rockwood classification in acute acromioclavicular joint injury does not correlate with symptoms

PURPOSE

Rockwood classified acromioclavicular (AC) joint injuries by displacement of the joint on radiographs. This classification has driven the management dogma of acute AC dislocation. The correlation between Rockwood grade and symptoms has not been described in acute injury. This study assesses that relationship.

METHODS

This series included 77 patients with acute AC joint injury (<6 weeks), treated between 2006 and 2015. Objective and patient-reported measures enabled correlation between clinical measures and Rockwood grade.

RESULTS

The mean age was 32 years (±11.86; range 17-59 years); 88% were male. Forty-four per cent were professional athletes and 43% suffered injury during rugby. The mean time from injury to presentation was 2 weeks (±1.64; range 0-5 weeks). There was poor correlation between Rockwood classification and pain (visual analogue scale) ( r_s = 0.05; p = 0.752). Poor correlation was noted between Rockwood grade and functional deficit (elevation ( r_s = 0.18; p = 0.275), abduction ( r_s = 0.19; p = 0.246) and strength ( r_s = 0.09; p = 0.579) vs. contralateral side). Oxford and Constant scores did not correlate with Rockwood grade ( r_s = 0.13; p = 0.972 and 0.01; p = 0.448, respectively).

CONCLUSION

The Rockwood grade does not correlate with clinical symptoms in acute AC joint injury. Previous evidence demonstrates the Rockwood classification's limitations in predicting the structures injured. Therefore, the reliability of using the Rockwood grade as a decision-making tool in the management of acute AC joint dislocation is unclear.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Comparison of magnetic resonance arthrography with arthroscopy for imaging of shoulder injuries: retrospective study

BACKGROUND Arthroscopy is the established 'gold standard' diagnostic investigation for detection of shoulder disorders. We aimed to compare the diagnostic accuracy of arthroscopy with magnetic resonance arthrography (MRA) for detection of shoulder disorders. METHODS Patients who underwent arthroscopy by a single surgeon and preoperative MRA between February 2011 and March 2012 for shoulder instability were identified. MRAs were reported by experienced musculoskeletal radiologists. Labral tears, anterior labral tears, superior labral anterior posterior (SLAP) lesions, posterior labral tears, rotator-cuff tears (RCTs), osteoarthritis, loose bodies and Hill-Sachs lesions were identified. Sensitivity, specificity, positive predictive value and negative predictive value, positive likelihood ratio and negative likelihood ratio were calculated. RESULTS A total of 194 patients were identified. The sensitivity and specificity for anterior labral tears was 0.60 and 0.92, SLAP lesions was 0.75 and 0.81, posterior labral tears was 0.57 and 0.96, any labral tear was 0.87 and 0.76, Hill-Sachs lesions was 0.91 and 0.91, RCTs was 0.71 and 0.86, osteoarthritis was 0.72 and 0.95, and loose bodies was 0.22 and 0.96, respectively. The positive predictive value and negative predictive value for anterior labral tears were 0.88 and 0.71, SLAP lesions was 0.64 and 0.88, posterior labral tears was 0.74 and 0.45, any labral tear was 0.89 and 0.71, Hill-Sachs lesions was 0.66 and 0.98, RCTs was 0.47 and 0.95, osteoarthritis was 0.70 and 0.95, and loose bodies was 0.27 and 0.95, respectively. CONCLUSIONS MRA has high diagnostic accuracy for labral tears and Hill-Sachs lesions, but whether MRA should be the first-line imaging modality is controversial.

Effects of a synovial fluid substitute on early recovery after arthroscopic subacromial decompression of the shoulder

PURPOSE

The purpose of this pilot study was to determine whether the use of a synovial fluid substitute (Viscoseal) after arthroscopic subacromial decompression (ASD) of the shoulder was safe (primary outcome) and effective in reducing the postsurgical pain on the day of surgery and the time from surgery to discharge (secondary outcomes), compared with patients undergoing standard ASD alone.

METHODS

Forty-six patients with primary isolated shoulder subacromial impingement were randomly assigned to either undergo SAD alone (control group: n = 21) or to receive 10 ml Viscoseal into the subacromial space at the end of the procedure (treatment group: n = 25).

RESULTS

No adverse events were reported in either group. All clinical scores improved significantly in each group from preoperative to 12-week follow-up (p < 0.01). The Viscoseal group experienced significantly (p = 0.001) less severe pain 4 h after the surgery {mean 54.0 ± 43.1, median 50 [interquartile range (IQR) 0-100]} and shorter time from surgery to discharge [mean 5.2 ± 1.4, median 5 (IQR 4-6)] than the control group [mean 102.4 ± 40.2, median 100 (IQR 50-150) and mean 11.0 ± 5.3, median 12 (IQR 6-16), respectively]. The Viscoseal group also required less analgesia postoperatively than the control group in the first 8 h: 24% of the Viscoseal required no analgesia, while all patients in the control group required analgesia; 24% of the control group required opiates compared with 4% in the Viscoseal group.

CONCLUSION

Viscoseal was safe and well tolerated after shoulder arthroscopy. It provided excellent pain relief and a faster discharge time after ASD of the shoulder. The use of Viscoseal should be investigated in larger randomized controlled trials and for other shoulder arthroscopy procedures.

LEVEL OF EVIDENCE

Level II, Pilot Prospective Comparative Study.

Part 1: Home-based family caregiving at the end of life: a comprehensive review of published quantitative research (1998-2008)

The changing context of palliative care over the last decade highlights the importance of recent research on home-based family caregiving at the end of life. This article reports on a comprehensive review of quantitative research (1998-2008) in this area, utilizing a systematic approach targeting studies on family caregivers, home settings, and an identified palliative phase of care (n = 129). Methodological challenges were identified, including: small, non-random, convenience samples; reliance on descriptive and bivariate analyses; and a dearth of longitudinal research. Robust evidence regarding causal relationships between predictor variables and carer outcomes is lacking. Findings suggest the need for knowledge regarding: family caregiving for patients with non-malignant terminal conditions; whether needs and outcomes differ between family caregivers at the end of life and comparison groups; and caregiver outcomes in bereavement. Clear definitions of 'family caregiving', 'end of life', and 'needs' are required as well as greater application and testing of theoretical and conceptual explanations.

Part 2: Home-based family caregiving at the end of life: a comprehensive review of published qualitative research (1998-2008)

Family caregivers are crucial for supporting home death. We reviewed published qualitative research on home-based family caregiving at end of life (1998-2008), synthesizing key findings and identifying gaps where additional research is needed. Multiple databases were searched and abstracts reviewed for a focus on family caregiving and palliative care; full articles were reviewed to extract data for this review. In total, 105 articles were included. Findings are presented in the following areas: the caregiving experience and contextual features; supporting family caregivers at end of life; caregiving roles and decision-making; and rewards, meaning and coping. We noted a lack of definitional clarity; a reliance on interview methods and descriptive, thematic analyses, and a relative lack of diversity of patient conditions. Research needs are identified in several areas, including the bereavement experience, caregiver ambivalence, access to services, caregiver meaning-making, and relational and contextual influences on family caregiving at end of life.

Supporting lay carers in end of life care: current gaps and future priorities

Informal carers are central to the achievement of end of life care and death at home and to policy aims of enabling patient choice towards end of life. They provide a substantial, yet hidden contribution to our economy. This entails considerable personal cost to carers, and it is recognised that their needs should be assessed and addressed. However, we lack good research evidence on how best to do this. The present position paper gives an overview of the current state of carer research, its gaps and weaknesses, and outlines future priorities. It draws on a comprehensive review of the carer literature and a consensus meeting by experts in the field. Carers' needs and adverse effects of caregiving have been extensively researched. In contrast, we lack both empirical longitudinal research and conceptual models to establish how adverse effects may be prevented through appropriate support. A reactive, "repair" approach predominates. Evaluations of existing interventions provide limited information, due to limited rigour in design and the wide variety in types of intervention evaluated. Further research is required into the particular challenges that the dual role of carers as both clients and providers pose for intervention design, suggesting a need for future emphasis on positive aspects of caregiving and empowerment. We require more longitudinal research and user involvement to aid development of interventions and more experimental and quasi-experimental research to evaluate them, with better utilisation of the natural experiments afforded by intra- and international differences in service provision.

Repair of distal biceps tendon rupture with the Biotenodesis screw

BACKGROUND

Distal biceps tendon ruptures are uncommon injuries with only around 300 cases reported in the literature. Current management tends to favour anatomical reinsertion of the tendon into the radial tuberosity, especially in young and active individuals. These injuries are commonly repaired using either a single anterior incision with suture anchors or the Boyd-Anderson dual incision technique.

CASE REPORT

We report the use of a bioabsorbable interference screw for the repair of distal biceps tendon rupture using a minimal incision technique. In this technique the avulsed tendon and a bioabsorbable screw are secured in a drill hole on the radial tuberosity using whip stitch and fibre wire sutures according to Biotenodesis system guidelines.

CONCLUSION

The technique described requires minimal volar dissection that is associated with a reduced number of synostosis and posterior interosseous nerve injuries. The bioabsorbable interference screw has all the advantages of being biodegradable and has been shown to have greater pullout strength than suture anchors. It is also a reasonable alternative to titanium screws in terms of primary fixation strength. The strong fixation provided allows early active motion and return to previous activities as seen in our case.

[Symptomatic pericardial effusion as initial manifestation of gastric signet ring cell carcinoma]

HISTORY

A 78-year-old woman presented at our hospital with palpitation, tachycardia and progressive dyspnea. The health history included the diagnosis of diabetes mellitus and chronic obstructive pulmonary disease.

INVESTIGATIONS

The ECG showed atrial fibrillation, later changing with sinus rhythm and low voltage. The echocardiography revealed pericardial effusion. The cytology showed signet ring cells from the stomach. Endoscopic study revealed a 3 cm tumor in the posterior wall of the upper part of the body. The histopathological examination diagnosed cancer of diffuse type according to Lauren, with signet-ring cells.

TREATMENT AND CLINICAL COURSE

After treating the atrial fibrillation a pericardial drainage was performed. The pericardiocentesis yielded 500 ml of serous fluid. In an echocardiogram after pericardial drainage, pericardial effusion was no longer present. During the clinical course the patient suffered a stroke and the chemotherapy could not be initiated. The patient died 2 months after diagnosis.

CONCLUSION

Cardiac involvement with clinical manifestations and pericardial effusion may be associated with a malignant neoplasm. Echocardiography and pericardiocentesis are helpful for the diagnosis of cardiac metastases.

Origin of atomic clusters during ion sputtering

Previous studies have shown that the size distributions of small clusters ( n < or = 40; n = number of atoms/cluster) generated by sputtering obey an inverse power law with an exponent between -8 and -4. Here we report electron microscopy studies of the size distributions of larger clusters ( n > or = 500) sputtered by high-energy ion impacts. These new measurements also yield an inverse power law, but one with an exponent of -2 and one independent of sputtering yield, indicating that the large clusters are produced when shock waves, generated by subsurface displacement cascades, ablate the surface.

Neurovascular contact of the brain stem in hypertensive and normotensive subjects: MR findings and clinical significance

BACKGROUND AND PURPOSE

About 20 years ago, a theory was put forward that neurovascular contact of the root entry zone (REZ) of the ninth and 10th cranial nerve is responsible for elevated blood pressure in patients with essential hypertension. To test this hypothesis, we used MR tomography and MR angiography to evaluate the presence and degree of neurovascular contact of the REZ of the ninth and 10th cranial nerves in patients with essential hypertension as compared with patients with renal parenchymal hypertension and normotensive healthy volunteers.

METHODS

Patients with essential hypertension (group 1; n = 33), renal parenchymal hypertension (group 2; n = 30), and normotensive healthy volunteers (group 3; n = 25) underwent high-resolution (axial and coronal) brain stem MR imaging and MR angiography. The images were interpreted consensually by two radiologists who were blinded to the patients' hypertensive status. Neurovascular contact was graded as vessel contact without associated brain stem deformity (grade I), vessel contact with associated brain stem deformity (grade II), or vessel contact with associated deformity and displacement of the brain stem (grade III).

RESULTS

Neurovascular contact of the REZ of the ninth and 10th cranial nerve on the left side was found in 48.5% in group 1, in 26.7% in group 2, and in 48.0% in group 3. The rate of neurovascular contact on the right side was 24.2%, 13.3%, and 40.0%, respectively. chi(2) analysis showed no statistical difference between the groups.

CONCLUSION

Neurovascular contact is not more frequent in patients with essential hypertension than in normotensive control subjects or in those with secondary hypertension; therefore, MR imaging cannot aid patient selection for neurosurgical vascular decompression.

Differential abilities of phorbol esters in inducing protein kinase C (PKC) down-regulation in noradrenergic neurones

1. The ability of several phorbol ester protein kinase C (PKC) activators (phorbol 12, 13-dibutyrate, PDB; phorbol 12, 13-diacetate, PDA; and 12-deoxyphorbol 13-acetate, dPA) to down-regulate PKC was studied by assessing their effects on electrical stimulation-induced (S-I) noradrenaline release from rat brain cortical slices and phosphorylation of the PKC neural substrate B-50 in rat cortical synaptosomal membranes. 2. In cortical slices which were incubated for 20 h with vehicle, acute application of PDB, PDA and dPA (0.1 - 3.0 microM) enhanced the S-I noradrenaline release in a concentration-dependent manner to between 200 - 250% of control in each case. In slices incubated with PDB (1 microM for 20 h), subsequent acute application of PDB (0.1 - 3.0 microM) failed to enhance S-I release, indicating PKC down-regulation. However, in tissues incubated with PDA or dPA (3 microM) for 20 h, there was no reduction in the facilitatory effect of their respective phorbol esters or PDB (0.1 - 3.0 microM) when acutely applied, indicating that PKC was not down-regulated. This was confirmed using Western blot analysis which showed that PDB (1 microM for 20 h) but not PDA (3 microM for 20 h) caused a significant reduction in PKCalpha. 3. Incubation with PDB for 20 h, followed by acute application of PDB (3 microM) failed to increase phosphorylation of B-50 in synaptosomal membranes, indicating down-regulation. In contrast, tissues incubated with PDA or dPA for 20 h, acute application of their respective phorbol ester (10 microM) or PDB (3 microM) induced a significant increase in B-50 phosphorylation. 4. Acutely all three phorbol esters elevate noradrenaline release to about the same extent, yet PDA and dPA have lower affinities for PKC compared to PDB, suggesting unique neural effects for these agents. This inability to cause functional down-regulation of PKC extends their unusual neural properties. Their neural potency and lack of down-regulation may be related to their decreased lipophilicity compared to other phorbol esters. 5. We suggest that PKC down-regulation appears to be related to binding affinity, where agents with high affinity, irreversibly insert PKC into artificial membrane lipid and generate Ca(2+)-independent kinase activity which degrades and deplete PKC. We suggest that this mechanism may also underlie the ability of PDB to down-regulate PKC in nerve terminals, in contrast to PDA and dPA.

Acute compartment syndrome after muscle rupture in a non-athlete

Acute compartment syndrome after muscle rupture, although rare, is a limb threatening condition, which warrants emergency treatment. The case of acute compartment syndrome secondary to a gastrocnemius muscle tear of the right lower leg, in a non-athlete is reported. To our knowledge, this is the only description of acute compartment syndrome due to muscle rupture in a non-athlete.

Compartment syndrome of the hand following intra-arterial injection of heroin

We report two cases of compartment syndrome of the hand and forearm, due to intra-arterial injection of heroin, managed by surgical fasciotomies alone. We also review the literature on the management of this condition.

Stage III and oestrogen receptor negativity are associated with poor prognosis after adjuvant high-dose therapy in high-risk breast cancer

We report on the efficacy and toxicity of a sequential high-dose therapy with peripheral blood stem cell (PBSC) support in 85 patients with high-risk stage II/III breast cancer. There were 71 patients with more than nine tumour-positive axillary lymph nodes. An induction therapy of two cycles of ifosfamide (total dose, 7.5 g m(-2)) and epirubicin (120 mg m(-2)) was given, and PBSC were harvested during G-CSF-supported leucocyte recovery following the second cycle. The PBSC-supported high-dose chemotherapy consisted of two cycles of ifosfamide (total dose, 12,000 mg m(-2)), carboplatin (900 mg m(-2)) and epirubicin (180 mg m(-2)). Patients were autografted with a median number of 3.7 x 10(6) CD34+ cells kg(-1) (range, 1.9-26.5 x 10(6)) resulting in haematological reconstitution within approximately 2 weeks following high-dose therapy. The toxicity was moderate in general, and there was no treatment-related toxic death. Twenty-one patients relapsed between 3 and 30 months following the last cycle of high-dose therapy (median, 11 months). The probability of disease-free and overall survival at 4 years were 60% and 83%, respectively. According to a multivariate analysis, patients with stage II disease had a significantly better probability of disease-free survival (74%) in comparison to patients with stage III disease (36%). The probability of disease-free survival was also significantly better for patients with oestrogen receptor-positive tumours (70%) compared to patients with receptor-negative ones (40%). Bone marrow samples collected from 52 patients after high-dose therapy were examined to evaluate the prognostic relevance of isolated tumour cells. The proportion of patients presenting with tumour cell-positive samples did not change in comparison to that observed before high-dose therapy (65% vs 71%), but a decrease in the incidence and concentration of tumour cells was observed over time after high-dose therapy. This finding was true for patients with relapse and for those in remission, which argues against a prognostic significance of isolated tumour cells in bone marrow. In conclusion, sequential high-dose chemotherapy with PBSC support can be safely administered to patients with high-risk stage II/III breast cancer. Further intensification of the therapy, including the addition of non-cross resistant drugs or immunological approaches such as the use of antibodies against HER-2/NEU, may be envisaged for patients with stage III disease and hormone receptor-negative tumours.

Immunomagnetic selection of CD34+ peripheral blood stem cells for autografting in patients with breast cancer

Contamination of transplants with tumour cells may contribute to relapse after peripheral blood stem cell transplantation (PBSCT). We studied the feasibility of CD34+ cell selection from blood-derived autografts obtained following G-CSF-supported cytotoxic chemotherapy in a group of 25 patients with breast cancer (10 with high-risk stage II/III and 15 with stage IV without bone or bone marrow involvement). Using immunomagnetic beads (Isolex 300 SA. Baxter) CD34+ cells were enriched and released by chymopapain resulting in a median purity of 95% (range 82-99%) and a median recovery of 80% (range 27-132%). The enrichment procedure did not change the proportion of CD34+ subsets coexpressing HLA-DR, CD38 and Thy-1, while L-selectin was removed from the cell surface following selection. Using a sensitive immunocytological technique with a cocktail of epithelial-specific antibodies (anti-cytokeratin 8, 18 and 19; HEA125; BM7 and BM8), five leukaphereses products contained epithelial cells, whereas the selected CD34+ cell fraction was free of tumour cells. A neutrophil count of 0.5 x 10(9)/l and a platelet count of 20 x 10(9)/l was reached after a median time of 14 and 10d following 40 high-dose chemotherapy (HDC) cycles. Our results indicate that immunomagnetic selection of CD34+ cells yields highly purified autografts devoid of tumour cells whereas the engraftment ability of the progenitor and stem cells is fully retained.

A prospective trial to compare three anaesthetic techniques used for the reduction of fractures of the distal radius

The aim of this study was to compare prospectively haematoma blocks alone and haematoma blocks with sedation with general anaesthesia for the reduction of distal radius fractures in adult patients, with respect to pain perception before, during and after manipulation using a visual analogue scale, radiological position, waiting time, procedure time and cost. Fifty-eight adult patients with closed, displaced distal radius fractures were included in the study. Pain experienced during manipulation was greatest in patients who received haematoma blocks alone compared with the other two groups. Post-manipulation pain was significantly greater in patients who received a general anaesthetic. Radiological correction was as good in those patients receiving a haematoma block with or without sedation as a general anaesthetic. The waiting and manipulation times and resource costs were greater in those receiving a general anaesthetic. There were no complications related to any of these anaesthetic methods. Patient acceptance is greater with a correctly performed haematoma block and sedation technique compared to general anesthesia. It is also more efficient with regard to time and the resources required. This is particularly important for a progressively increasing ambulatory, elderly population who require prompt, safe, effective and painless management.

Subclassification of presynaptic alpha 2-adrenoceptors: alpha 2A-autoreceptors in rabbit atria and kidney

The study was devised to classify, by means of antagonist affinities, the presynaptic alpha 2-autoreceptors of rabbit atria and kidney in terms of alpha 2A, alpha 2B, alpha 2C and alpha 2D. A set of antagonists was chosen that was able to discriminate between the four subtypes. Small pieces of the left atrium and slices of the kidney cortex were preincubated with 3H-noradrenaline and then superfused and stimulated electrically. In one series of experiments, tissue pieces were stimulated by relatively long pulse trains (1 or 2 min) leading to alpha 2-autoinhibition. All 11 (atria) or 10 (kidney) antagonists increased the evoked overflow of tritium. pEC30% values (concentrations causing 30% increase) were interpolated from concentration-response curves. In a second series of experiments, tissue pieces were stimulated by brief pulse trains (0.4 s) that did not lead to alpha 2-autoinhibition, and concentration-inhibition curves of the alpha 2-selective agonist 5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline (UK 14,304) were determined. Most of the 11 (atria) or 8 (kidney) antagonists shifted the concentration-inhibition curve of UK 14,304 to the right. pKd values of the antagonists were calculated from the shifts. pEC30% values correlated with pKd values, both in atria (r = 0.728) and in the kidney (r = 0.930). pEC30% values in atria correlated with pEC30% values in the kidney (r = 0.988) and pKd values in atria correlated with pKd values in kidney (r = 0.923). It is concluded that the alpha 2-autoreceptors in atria and the kidney are the same. Comparison with antagonist affinities for prototypic native alpha 2 binding sites, alpha 2 binding sites in cells transfected with alpha 2 subtype genes, and previously classified presynaptic alpha 2-adrenoceptors--all taken from the literature--indicates that both autoreceptors are alpha 2A. This conclusion is reached with either of the two independent estimates of autoreceptor affinity, pEC30% and pKd. The results are compatible with the hypothesis that at least the majority of alpha 2-autoreceptors belong to the alpha 2A/D branch of the alpha 2-adrenoceptor tree, across mammalian or at least rodent and lagomorph species.

Subclassification of presynaptic alpha 2-adrenoceptors: alpha 2D-autoreceptors and alpha 2D-adrenoceptors modulating release of acetylcholine in guinea-pig ileum

The study was designed to classify in terms of alpha 2A, alpha 2B, alpha 2C and alpha 2D the presynaptic alpha 2-autoreceptors, as well as the alpha 2-receptors modulating the release of acetylcholine, in the myenteric plexus-longitudinal muscle (MPLM) preparation of the guinea-pig ileum. A set of antagonists was chosen that was able to discriminate between the four subtypes. Small pieces of the MPLM preparation were preincubated with 3H-noradrenaline or 3H-choline and then superfused and stimulated electrically. The stimulation periods used (3H-noradrenaline: 3 trains of 20 pulses, 50 Hz, train interval 60 s; 3H-choline: single trains of 30 pulses, 0.2 Hz) did not lead to alpha 2-autoinhibition or inhibition of 3H-acetylcholine release by endogenous noradrenaline. The alpha 2-selective agonist 5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline (UK 14,304) reduced the evoked overflow of tritium in both 3H-noradrenaline and 3H-choline experiments. Most (3H-noradrenaline) or all (3H-choline) of the 10 antagonists shifted the concentration-inhibition curves of UK 14,304 to the right. pKd values of the antagonists were calculated from the shifts. pKd values from 3H-noradrenaline experiments correlated with pKd values from 3H-choline experiments (r = 0.981). It is concluded that alpha 2-autoreceptors and alpha 2-heteroreceptors modulating the release of acetylcholine in the MPLM preparation are of the same subtype. Comparison with antagonist affinities for prototypic native alpha 2 binding sites, binding sites in cells transfected with alpha 2 subtype genes, and previously classified presynaptic alpha 2-adrenoceptors--all taken from the literature--indicates that both are alpha 2D.(ABSTRACT TRUNCATED AT 250 WORDS)