Degenerative rotator cuff tear, repair or not repair? A review of current evidence

INTRODUCTION

We review the literature and highlight the important factors to consider when counselling patients with non-traumatic rotator cuff tears on which route to take. Factors include the clinical outcomes of surgical and non-surgical routes, tendon healing rates with surgery (radiological outcome) and natural history of the tears if treated non-operatively.

METHODS

A PRISMA-compliant search was carried out, including the online databases PubMed and Embase™ from 1960 to the end of June 2018.

FINDINGS

A total of 49 of the 743 (579 PubMed and 164 Embase™) results yielded by the preliminary search were included in the review. There is no doubt that the non-surgical route with an appropriate physiotherapy programme has a role in the management of degenerative rotator cuff tears. This is especially the case in patients with significant risk factors for surgery, those who do not wish to go through a surgical treatment and those with small, partial and irreparable tears. However, rotator cuff repair has a good clinical outcome with significant improvements in pain, range of motion, strength, quality of life and sleep patterns.

The influence of the mechanical environment on remodelling of the patellar tendon

An understanding of the remodelling of tendon is crucial for the development of scientific methods of treatment and rehabilitation. This study tested the hypothesis that tendon adapts structurally in response to changes in functional loading. A novel model allowed manipulation of the mechanical environment of the patellar tendon in the presence of normal joint movement via the application of an adjustable external fixator mechanism between the patella and the tibia in sheep, while avoiding exposure of the patellar tendon itself. Stress shielding caused a significant reduction in the structural and material properties of stiffness (79%), ultimate load (69%), energy absorbed (61%), elastic modulus (76%) and ultimate stress (72%) of the tendon compared with controls. Compared with the material properties the structural properties exhibited better recovery after re-stressing with stiffness 97%, ultimate load 92%, energy absorbed 96%, elastic modulus 79% and ultimate stress 80%. The cross-sectional area of the re-stressed tendons was significantly greater than that of stress-shielded tendons. The remodelling phenomena exhibited in this study are consistent with a putative feedback mechanism under strain control. This study provides a basis from which to explore the interactions of tendon remodelling and mechanical environment.

Collagenous microstructure of the glenoid labrum and biceps anchor

The glenoid labrum is a significant passive stabilizer of the shoulder joint. However, its microstructural form remains largely unappreciated, particularly in the context of its variety of functions. The focus of labral microscopy has often been histology and, as such, there is very little appreciation of collagen composition and arrangement of the labrum, and hence the micromechanics of the structure. On transmission electron microscopy, significant differences in diameter, area and perimeter were noted in the two gross histological groups of collagen fibril visualized; this suggests a heterogeneous collagenous composition with potentially distinct mechanical function. Scanning electron microscopy demonstrated three distinct zones of interest: a superficial mesh, a dense circumferential braided core potentially able to accommodate hoop stresses, and a loosely packed peri-core zone. Confocal microscopy revealed an articular surface fine fibrillar mesh potentially able to reduce surface friction, bundles of circumferential encapsulated fibres in the bulk of the tissue, and bone anchoring fibres at the osseous interface. Varying microstructure throughout the depth of the labrum suggests a role in accommodating different types of loading. An understanding of the labral microstructure can lead to development of hypotheses based upon an appreciation of this component of material property. This may aid an educated approach to surgical timing and repair.

Qualitative and quantitative descriptions of glenohumeral motion

Joint modelling plays an important role in qualitative and quantitative descriptions of both normal and abnormal joints, as well as predicting outcomes of alterations to joints in orthopaedic practice and research. Contemporary efforts in modelling have focussed upon the major articulations of the lower limb. Well-constrained arthrokinematics can form the basis of manageable kinetic and dynamic mathematical predictions. In order to contain computation of shoulder complex modelling, glenohumeral joint representations in both limited and complete shoulder girdle models have undergone a generic simplification. As such, glenohumeral joint models are often based upon kinematic descriptions of inadequate degrees of freedom (DOF) for clinical purposes and applications. Qualitative descriptions of glenohumeral motion range from the parody of a hinge joint to the complex realism of a spatial joint. In developing a model, a clear idea of intention is required in order to achieve a required application. Clinical applicability of a model requires both descriptive and predictive output potentials, and as such, a high level of validation is required. Without sufficient appreciation of the clinical intention of the arthrokinematic foundation to a model, error is all too easily introduced. Mathematical description of joint motion serves to quantify all relevant clinical parameters. Commonly, both the Euler angle and helical (screw) axis methods have been applied to the glenohumeral joint, although concordance between these methods and classical anatomical appreciation of joint motion is limited, resulting in miscommunication between clinician and engineer. Compounding these inconsistencies in motion quantification is gimbal lock and sequence dependency.

Tensile properties of the human glenoid labrum

Human fresh-frozen cadaveric glenoid labrae from 16 donors were harvested and ten of these had no gross degeneration. These ten were divided into eight equal circumferential sections. Each section was cut to produce test-samples from the core layer with a cross-section of 1 x 1 mm. Tensile testing was performed within a controlled environment unit at 37 +/- 1 degrees C and 100% relative humidity. Each test-sample was precycled to a quasi-static state to alleviate the effects of deep-freezing, prior to final testing. The tangent modulus was calculated for each test-sample before and after a 5-min period of stress relaxation and at yield. The mean elastic modulus and yield stress of the glenoid labrum were 22.8 +/- 11.4 and 2.5 +/- 2.1 MPa, respectively. The anterosuperior portion had a lower elastic modulus and lower yield stress than the inferior portion (both P < 0.02). The pre-stress relaxation tangent modulus was significantly lower than the post-stress relaxation tangent modulus for all portions of the labrum. The glenoid labrum has similar tensile material properties to articular cartilage. Its elastic modulus varies around its circumference. This suggests that the labrum may encounter different forces at different positions.

Glenohumeral motion: review of measurement techniques

Measurement of upper limb motion is problematic, not least because of the large range of path dependent description of motion of the joints, and the multiple non-cyclical unstandardised motion tasks measured. Furthermore, appreciation of shoulder motion specifically is obscured by overlying soft tissue. In order to satisfy the complexity of a clinically useful model of the movement of the joint, input data must be acquired from a set of pre-determined movements using a non-invasive technique with a high level of accuracy. Descriptive and predictive modeling of the glenohumeral joint requires input of high-fidelity data into a 6 degree of freedom representation, without which, the application of the tool is of limited clinical significance to the advancement of both operative and non-operative management of shoulder pathology. Electromagnetic, linkage and radiographic techniques have previously been used, however, an optimal solution is yet to be described.

Mechanical factors in the initiation and propagation of tears of the rotator cuff. Quantification of strains of the supraspinatus tendon in vitro

Differential strain has been proposed to be a causative factor in failure of the supraspinatus tendon. We quantified the strains on the joint and bursal sides of the supraspinatus tendon with increasing load (20 to 200 N) and during 120 degrees of glenohumeral abduction with a constant tensile load (20 to 100 N). We tested ten fresh frozen cadaver shoulders on a purpose-built rig. Differential variable reluctance extensometers allowed calculation of the strain. Static loading to 100 N or more increased strains on the joint side significantly more than on the bursal side. During glenohumeral abduction an increasing and significant difference in strain was measured between the joint and bursal sides of the supraspinatus tendon, which reached a maximum of 10.6% at abduction of 120 degrees. The joint side strain of 7.5% reached values which were previously reported to cause failure. Differential strain causes shearing between the layers of the supraspinatus tendon, which may contribute to the propagation of intratendinous defects that are initiated by high joint side strains.

Magic angle imaging of the achilles tendon in patients with chronic tendonopathy

AIMS

To assess the Achilles tendon in patients with chronic tendonopathy using magnetic resonance (MR) magic angle imaging, and to compare the appearances and uptake of contrast medium in abnormal tendons with those in normal tendons.

MATERIAL AND METHODS

Eight patients with chronic Achilles tendonopathy and five normal controls were examined with the long axis of the tendon placed at 55 degrees and at 0 degrees to the main magnetic field. Conventional two-dimensional (2D) multi-slice images were obtained and T1 values were calculated before, and for up to 1h after the administration of intravenous gadodiamide. Both the unenhanced appearance and the pattern of enhancement in the tendon were compared.

RESULTS

In the patients with tendonopathy, high signal intensity areas were evident on the short T1 inversion recovery (STIR) images obtained at 55 degrees in all tendons. Contrast medium enhancement was seen in six tendons and was most obvious on the images obtained at the magic angle. This was initially focal and then spread more diffusely within the tendon. After contrast medium administration, T1 values were significantly reduced in the tendonopathy group compared with normal controls (p<0.01). On the late post-contrast medium images obtained at 55 degrees, enhancement was evident in most of the tendon and correlated well with high signal intensity seen on STIR images.

CONCLUSION

The use of magic angle MR imaging improved the demonstration of signal changes in the Achilles tendon in chronic tendonopathy. The STIR images obtained at the magic angle showed more obvious signal change than those obtained at 0 degrees. The changes due to enhancement were much more evident on images obtained at 55 degrees than at 0 degrees. The uptake of contrast medium was greater in the patients than in normal controls.

Magnetic resonance: magic angle imaging of the Achilles tendon

Tendons do not normally produce detectable signals with conventional magnetic-resonance techniques and are recognised as dark signal voids. However, if tendons are examined at 55 degrees to the static magnetic field (the "magic angle"), signals become detectable and the tendons can become the brightest structure on the image. We have used this approach to establish tendon relaxation times and magnetisation transfer ratios and to show contrast enhancement. We have also shown more detail of acute and chronic tendon rupture by this method compared with images made with the tendon parallel to the static magnetic field.

Electrothermal shrinkage reduces laxity but alters creep behavior in a lapine ligament model

Thermal denaturation of collagen in ligament tissue has the potential to enhance arthroscopic shoulder stabilization. Previous studies have shown that laser energy produces significant capsular shortening without alteration of viscoelastic properties, but little information is available on the effects of radio frequency electrothermal energy. We assessed the acute effects of radio frequency shrinkage with use of the lapine medial collateral ligament model, in which the tibial insertion was shifted proximally to produce abnormal laxity. Thermal treatment resulted in restoration of laxity from 3.33 +/- 0.25 mm to 0.66 +/- 0.31 mm, which was not significantly different from medial collateral ligaments replaced anatomically (0.50 +/- 0.34 mm). When tested at 4.1 megapascals, cyclic and static creep strains were increased twofold to threefold in thermally-treated ligaments (P <.01), and partial failure occurred in 2 of 8 cases. We conclude that radio frequency electrothermal shrinkage is effective at reducing laxity but significantly alters viscoelastic properties, posing a risk of recurrent stretching-out at "physiological" loads.

Structural properties of the intact and the reconstructed coracoclavicular ligament complex

Numerous procedures have been described for the operative management of acromioclavicular joint injuries, but surprisingly little information is available on the ultimate mechanical behavior of the native coracoclavicular ligament complex or on the various methods of reconstruction. We tested 19 fresh-frozen cadaveric bone-ligament-bone preparations of the coracoclavicular ligament in uniaxial tension at 25 mm/min until failure. Seven specimens were left intact, six had the trapezoid ligament sectioned, and six had the conoid ligament sectioned. Reconstruction of the coracoclavicular ligament was achieved using coracoacromial ligament transfers, woven polyester slings, suture anchors, and Bosworth screws; all reconstructions were also tested to failure. The intact coracoclavicular ligament failed by avulsion or midsubstance tear at 500 (+/-134) N, with a stiffness of 103 (+/-30) N/mm and elongation to failure of 7.7 (+/-1.9) mm. There was no significant difference between the contributions of the conoid or trapezoid ligaments in this loading configuration. Coracoclavicular slings and suture anchors provided strength similar to that of the coracoclavicular ligament, but with significantly greater deformations (14 to 26 mm). Screw fixation resulted in comparable stiffness and superior strength to the coracoclavicular ligament, but only if bicortical purchase was obtained. Coracoacromial ligament transfers were the weakest and least stiff, and augmentation with another form of coracoclavicular fixation is recommended. These results provide a useful baseline for comparison of the initial performance of reconstructive techniques with the performance of the native coracoclavicular ligament.

Resurfacing of the glenoid in total shoulder arthroplasty. A comparison, at a mean of five years, of prostheses inserted with and without cement

BACKGROUND

Clinically evident loosening of a glenoid component inserted with cement in total shoulder arthroplasty is infrequent, but radiographic changes that indicate loosening at the implant-bone interface are common and have been associated with functional limitation. We compared the results of total shoulder arthroplasties in which the glenoid implant had been inserted with cement with those of arthroplasties in which a bone-ingrowth glenoid implant had been inserted without cement.

METHODS

The results of eighty-six consecutive total shoulder arthroplasties, performed by the same surgeon, were retrospectively reviewed between four and seven years after the operation. Fifty-eight shoulders in which the primary glenoid implant was in situ were assessed with use of the Simple Shoulder Test and Short Form-36 questionnaires, clinical examination, and fluoroscopic imaging of the glenoid implant-bone interface. Thirty-two of the glenoid components had been fixed with cement and twenty-six, without cement.

RESULTS

Complications occurred in 16 percent (fourteen) of the eighty-six shoulders, and 9 percent (eight) of the shoulders needed a revision operation. None of the revisions were done because of loosening of the glenoid component. Five of the eight revisions involved implants that had been inserted without cement. Three of these implants were revised because of early instability and two, because the polyethylene component had separated from the metal tray of the glenoid implant. With the numbers available, we could not detect any significant differences between the groups with respect to pain, range of motion, function of the shoulder, or general health. Radiographic analysis demonstrated a high level of interobserver agreement (kappa = 0.89). Radiolucent lines were observed after 41 percent (thirteen) of the thirty-two arthroplasties performed with cement compared with 23 percent (six) of the twenty-six arthroplasties performed without cement. The proportion of implants classified as probably loose was approximately three times greater in the group in which cement had been used. Eccentric wear of the posterior rim of the metal tray and focal osteolysis under the metal tray were observed in the group in which the component had been inserted without cement; these findings may indicate a potential for progression of radiographic loosening with increased durations of follow-up.

CONCLUSIONS

We concluded that, despite the higher rate of early complications, the intermediate-term outcomes of arthroplasties in which the glenoid implant is inserted without cement are comparable with those of arthroplasties with cementing of the glenoid component.

Intraoperative assessment of tibiofemoral contact stresses in total knee arthroplasty

The production of polyethylene wear debris in total knee arthroplasty (TKA) is due to multiple factors. In particular, inadequate implant alignment and high bearing surface contact stresses are associated with polyethylene failure. Optimal implant placement and soft tissue balancing may contribute to reducing wear and the production of polyethylene particles. We present a case in which a quantitative technique was used to measure tibiofemoral contact stresses during implantation of a total knee prosthesis in vivo. In a knee with preoperative varus and fixed flexion deformity, medial compartment contact stresses after initial resection were reduced from 14.3 MPa to 11.3 MPa in neutral alignment by additional bone resection. Posterior cruciate release was required to reduce contact stresses further and to provide satisfactory balance between medial and lateral compartments, as determined by the operating surgeon, and was confirmed by the measurement system (3.8 MPa medially; 3.0 MPa laterally). This technique has potential to fine-tune implant positioning and ligament balancing during TKA.

THE INTEROSSEOUS MEMBRANE IN RADIO-ULNAR DISSOCIATION

In severe forearm injuries, the diagnosis of disruption of the interosseous membrane is frequently delayed and sometimes missed, giving difficulties in the salvage of forearm stability.

We studied the structure and function of the interosseous membrane in 11 cadaver preparations, using mechanical and histological analysis. Seven of the specimens tested in uniaxial tension sustained a mid-substance tear of the central band of the membrane at a mean peak load of 1038 ± 308 N. The axial stiffness was 190 ± 44 N/mm with elongation to failure of 10.34 ± 2.46 mm. These results provide criteria for the evaluation of reconstructive methods.

A preliminary clinical investigation of the use of ultrasound suggests that this may be of value in the screening of patients with complex fractures of the forearm, and for investigating the natural history of tears of the interosseous membrane.

The interosseous membrane in radio-ulnar dissociation

In severe forearm injuries, the diagnosis of disruption of the interosseous membrane is frequently delayed and sometimes missed, giving difficulties in the salvage of forearm stability. We studied the structure and function of the interosseous membrane in 11 cadaver preparations, using mechanical and histological analysis. Seven of the specimens tested in uniaxial tension sustained a mid-substance tear of the central band of the membrane at a mean peak load of 1038 +/- 308 N. The axial stiffness was 190 +/- 44 N/mm with elongation to failure of 10.34 +/- 2.46 mm. These results provide criteria for the evaluation of reconstructive methods. A preliminary clinical investigation of the use of ultrasound suggests that this may be of value in the screening of patients with complex fractures of the forearm, and for investigating the natural history of tears of the interosseous membrane.

The design and performance of an experimental external fixation device with load transducers

It is becoming increasingly common that fracture healing is modelled in the laboratory with an osteotomy in the diaphysis of the ovine tibia. External fixation is often used to hold the bones in these models, presenting the problem that the loads on such devices are poorly understood. To help investigate this, a unilateral device has been developed which is capable of measuring the two components of load considered to be the most important, that of axial compression and bending in the plane of the fixator. The device was found to be a rigid system and easy to apply, with the in-vivo measurements being straightforward. The estimated limits of error of the compression transducer are +37.9 N and -21.4 N and those of the bending transducer are +3.6 Nm and -4.2 Nm. Preliminary measurements showed the maximum load during normal walking to 345 N compression and 28 Nm in-plane bending.

Measurement of serum angiogenic factor in devascularized experimental tibial fractures

Early recovery of the vasculature is of profound importance in healing fractures, but the exact role of the regenerating endothelium remains controversial. Serum activity of endothelial cell-stimulating angiogenesis factor (ESAF) was measured after tibial osteotomy in two groups of sheep over a period of 42 days. Each osteotomy was held in an instrumented external fixator, and in one group the musculoperiosteal vasculature was excluded from the osteotomy site. In the well-vascularized group (n = 4), ESAF activity was significantly higher 2-5 days after osteotomy, with a peak at 4 days (21.1 +/- 5.4, p < 0.05), and displayed a biphasic pattern of secretion with a second peak at 7 days (24.3 +/- 5.5). In the devascularized group (n = 4) overall activity was lower, with only a single peak occurring at 9 days (17.5 +/- 3.2). These findings were correlated with significant differences in structural properties and on histological examination. The early detection of such regional vascular responses may prove to be of significant clinical value in high-energy trauma, enabling prediction of those fractures at risk of delayed or nonunion.

Humoral regulation of blood flow in the vertebral endplate

STUDY DESIGN

Blood flow in the sheep lumbar spine was measured.

OBJECTIVES

The effect of vasoactive agents, noradrenaline and acetylcholine, on blood flow adjacent to the disc--bone interface was determined.

SUMMARY OF BACKGROUND DATA

The main route for disc nutrition is through the vertebral endplate. Although the vascular anatomy in this region has been well described, its response to neurohumoral influences has not been quantified.

METHODS

Blood flow in bone adjacent to the lumbar intervertebral discs was measured using the microsphere technique before and after infusions of noradrenaline and acetylcholine in two groups of five female sheep. Systemic arterial pressure was measured during each infusion.

RESULTS

Vertebral bone blood flow was unchanged during noradrenaline infusion, but increased by 60% during acetylcholine infusion. This was associated with a significant decrease in systemic arterial pressure.

CONCLUSIONS

These data are consistent with the existence of muscarinic receptors in vessels of the vertebral endplate, which suggests that the vasculature may influence disc nutrition.

The vascular response to fracture micromovement

Micromovement has been shown to promote the healing of experimental fractures, but its role in the clinical management of fractures with soft-tissue injury is less certain. In a 2-mm transverse osteotomy of the ovine tibia held in an instrumented external fixator, axial interfragmentary displacement was quantified in vivo for six weeks after osteotomy. Group I (n = 11) had an axial fixation stiffness of 460 N/mm and Group II (n = 12) had a stiffness of 238 N/mm. With a 25% difference in micromovement, a fourfold change in corticomedullary blood flow was observed at two weeks after osteotomy (p < 0.01). Although by six weeks mechanical properties in torsion were similar, there were marked differences in the periosteal cross-sectional perimeter, area, and intracortical porosity that complemented the hemodynamic changes. The early vascular response is very sensitive to the initial mechanical environment, and appears to precede and determine the organization of osteogenesis. Further understanding of this relationship may prove to be of direct clinical relevance in the augmentation of healing of devascularized diaphyseal fractures.

Quantitative early phase scintigraphy in the prediction of healing of tibial fractures

Imaging with technetium-99m methylene diphosphonate (99mTc-MDP) is established in the diagnosis of infection, neoplasia and ischaemic necrosis in orthopaedic practice, but its role in fracture healing is less well-defined. Previous studies have shown a relationship between fracture site activity (region A), activity in adjacent normal bone (region C) and time to union. The predictive value of the A/C ratio of the image obtained 300-800 s after injection was assessed in a prospective study of 50 patients with closed tibial fractures managed with plaster casts, external fixators and intramedullary nails. There were significant differences in absolute uptake and A/C ratio between the three groups (P less than 0.05), but this was not related to time to union. Reamed nailing alters the distribution of 99m-Tc-MDP uptake so as to reduce the A/C ratio (1.10 +/- 0.20), but there is a promising role for early phase bone scanning in non-operative (A/C = 1.40 +/- 0.21) or externally fixed (A/C = 1.26 +/- 0.22) fractures in conjunction with other non-invasive methods of monitoring the biomechanical environment.

Increased endothelial cell stimulating angiogenesis factor in patients with tibial fractures

Angiogenesis is an important step in the normal process of fracture healing, irrespective of the method of fixation. Using a quantitative assay, the amount of endothelial cell stimulating factor (ESAF) has been determined in a small group of patients with tibial fractures. ESAF levels were found to be increased when compared with normal volunteers, although this increase was relatively less in fractures held with intramedullary nails than with external fixation.

The effect of devascularisation upon early bone healing in dynamic external fixation

We examined the effect of periosteal devascularisation upon the early healing of osteotomies of sheep tibiae held in an instrumented external fixation system with an axial stiffness of 240 N/mm. At 14 days, cortical blood flow measured by the microsphere technique was 19.3 ml/min/100g in the well-vascularised osteotomies, but only 1.7 ml/min/100g in the devascularised osteotomies, despite an increase in medullary flow (p less than 0.0005). Delay in healing of the devascularised osteotomies was suggested by an in vivo monitoring system and confirmed by post-mortem mechanical testing. We suggest that the osteogenic stimulus of dynamic external fixation is dependent on the early restoration of cortical blood flow in devascularised fractures.

Influence of nutritional status on growth hormone-dependent circulating somatomedin-C activity in mature sheep

The effect of daily administration of ovine GH for a period of 4 weeks on somatomedin-C biological activity in plasma was investigated in mature Merino sheep fed a maintenance energy intake (low plane; LP) or 1.6 times this amount (high plane; HP). The GH treatment resulted in a significant (P less than 0.05) increase in plasma GH levels in blood samples collected 23.5 h after each daily injection in both LP and HP groups. Plasma concentrations of somatomedin-C activity and insulin were significantly stimulated to a maximum level by the third GH injection and remained at this level for 7 days. Subsequently, circulating levels of both hormones fell to 40-50% of the peak response to GH and returned to basal levels within 48 h of the cessation of GH injections. In the HP group the response of plasma insulin and somatomedin-C activity to GH injection was greater than in the LP group.

Juxta-articular bone lesions in tertiary yaws

A case of tertiary yaws in an immigrant from the Solomon Islands is presented. The report highlights the atypical features and diagnostic difficulties of late-stage treponemal infection.

Effects of growth hormone administration on wool growth in merino sheep

The effects of daily administration of 10 mg of highly purified ovine growth hormone (GH) for a period of 4 weeks on wool growth have been measured in 12 Merino ewes fed either a calculated maintenance energy intake or 1.6 times this amount (six on each ration). Concentrations of hormones, glucose, urea, alpha-amino N and amino acids in the blood were monitored and faeces and urine collected for measurement of nitrogen balance. Wool growth rate decreased by 20% during the 4 weeks of GH treatment in sheep fed the high energy diet, largely because of reduced wool fibre diameter. This was followed by restoration of normal growth and then an increase of up to 20% above control levels, a response which persisted for 12 weeks following cessation of GH administration, and which was due to increases in both fibre length and diameter. GH administration caused marked increases in plasma concentrations of GH, insulin and somatomedin C, glucose and free fatty acids, all of which returned to basal levels following cessation of GH administration. No consistent changes in plasma concentration of T3, T4, cortisol, prolactin or alpha amino N were detected. Plasma urea and methionine levels decreased during GH treatment and returned to, or were raised above, basal levels after the GH treatment period. GH injection also resulted in a net retention of N during treatment, followed by a transient period of net N loss. The GH-induced changes in wool growth may be caused by a change in the partitioning of amino acids between the muscle mass and the skin. No other contributing factor(s) were identified.

Kinetic analysis of hydrocortisone effect on the neodifferentiation of Kirsten murine sarcoma virus-transformed human skin fibroblasts to adipose cells

Here we have demonstrated that transformation of human skin fibroblasts (SF) by the Kirsten murine sarcoma virus (KiMSV) is associated with their neodifferentiation into preadipose cells. Hydrocortisone (HC) and dexamethasone (DX) promoted the transformation/neodifferentiation of preadipocytes into mature fat cells. The effects of HC on the expression of adipocyte-containing foci (ACF) and on the total number of transformed foci (TTF) present in KiMSV-treated SF cultures were optimal at a concentration of about 500 ng/ml, or 1.25 X 10(-6) M. At this concentration of HC, the occurrence of ACF varied between 25 and up to 100% of the TTF formed in virus-treated cell cultures. In contrast, equimolar concentrations of estrogenic, androgenic, or progestational steroids inhibited ACF formation. The continued presence of HC post virus inoculation was necessary to effect optimal adipocytic conversion in KiMSV-treated cultures. Moreover, cell cultures that were "primed" with HC for up to 25 days or more prior to virus inoculation showed a further increase of TTF and of ACF at 14-21 days postinoculation. It is likely that the ras oncogene and HC can effect transformation/neodifferentiation of cells in a variety of normal or diseased human tissues de novo.

Oestrogen and seasonal effects on the production of an oestrus-associated glycoprotein in oviducal fluid of sheep

In 14 cyclic ewes, the oestrus-associated glycoprotein in the oviducal fluid was never detected between Days 7 and -2 of the oestrous cycle and it was present in 5% of fluid samples collected on Day -1, 59% on Day 0, 96% on Day 1, 100% on Day 2, 79% on Day 3, 31% on Day 4, 16% on Day 5, and 4% on Day 6. Its presence generally coincided with the period of high flow rate of oviducal fluid which occurs around oestrus. The duration of detectable levels of the oestrus-associated glycoprotein did not vary significantly during the breeding season from a mean (+/- s.d.) of 3.9 +/- 1.0 days. However, the peak flow rate of oviducal fluid dropped from 1.63 +/- 0.50 (early) to 1.38 +/- 0.40 (mid-) and to 0.85 +/- 0.21 ml/day late in the season. Anoestrous ewes (3) induced to ovulate by treatment with progesterone implants and gonadotrophin showed low peak fluid flow rates (0.92 +/- 0.30 ml/day) and the presence of the oestrus-associated glycoprotein for a shorter period (2.7 +/- 0.7 days). Pregnancy (N = 3) did not appear to prolong the production of the protein. The injection of 25 micrograms oestradiol benzoate into 3 anoestrous, 2 mid-cycle and 9 ovariectomized ewes caused an increase in fluid flow rate and appearance of the glycoprotein 1-2 days later. The glycoprotein was present for a longer period in response to the exogenous oestrogen--6.8 +/- 1.6 days in the ovariectomized ewes, 7.9 +/- 1.3 days in anoestrous ewes, and 8.4 +/- 0.8 days in the dioestrous ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydrocortisone promotes the neodifferentiation of Kirsten murine sarcoma virus transformed human skin fibroblasts to adipose cells: relevance to oncogenic mechanisms

Here we have demonstrated that transformation of human skin fibroblasts (SF) by the Kirsten murine sarcoma virus (KiMSV) is associated with their neodifferentiation into preadipose cells. Hydrocortisone (HC) promotes the transformation/neodifferentiation of such preadipocytes into mature fat cells. The effects of HC on the expression of adipocyte-containing foci and on the total number of transformed foci present in KiMSV-treated cultures appeared to be dose-dependent and was optimal at a concentration of about 500 ng/ml, or 1.25 X 10(-6) M. Although increasing serum concentrations (2-15%) increased the total number of transformed foci, it had no effect on the expression of adipocyte-containing foci in the presence of HC. The virus-induced preadipocytes undergoing partial conversion in the presence of HC were capable of clonal expansion and extensive proliferative activity. In contrast, mature adipocytes were terminally differentiated and as such have lost their ability to proliferate. The results suggest a role for a ras oncogene and HC in the transformation/neodifferentiation of human cells that might ultimately lead to cancer in some fraction of such cells.

Evaluation of a rosette inhibition test for pregnancy diagnosis in pigs

A rosette inhibition test was developed using pig lymphocytes and sheep red blood cells. Antilymphocyte serum (ALS) in the presence of complement inhibited rosette formation by greater than 95% at 1/250 declining to no inhibition at 1/8000. Sera obtained from a total of 14 pregnant sows before and 1, 2, 3 and 4 wk after mating were tested for their ability to augment the rosette depression caused by ALS. In one experiment in which the responses of 4 pregnant sows were compared to 4 non-pregnant sows by discriminant analysis, sera were classified correctly in 83% of the samples taken from either pregnant or non-pregnant sows. When the more usual method of calculating the rosette inhibition titre was used, the responses of sera from pregnant pigs were classified with 31% accuracy and those from non-pregnant pigs with 80% accuracy. In a second experiment, sera from 10 pregnant sows were classified with 25% accuracy using the rosette inhibition titre. Thus 4 of these pigs were classified as non-pregnant by this method. Data from the second experiment were not suitable for discriminant analysis. It was concluded that there was some factor present in the sera of pregnant pigs, particularly by 3 or 4 wk post-mating, which could be detected by the rosette inhibition test. However, the test is not sensitive enough to allow specific diagnosis of early pregnancy in pigs.

Identification of an oestrus-associated glycoprotein in oviducal fluid of the sheep

Samples of oviducal fluid were collected daily from sheep with indwelling catheters. Fluid samples taken from both oviducts of 2 sheep for 2 cycles during the middle of the breeding season (April/May) (8 sets of data) were compared with 9 sets of data generated from 2 cycles in 3 sheep later in the breeding season (June/July). Around the period of oestrus, the output of oviducal fluid increased to a peak volume of 1.56 +/- 0.35 ml per day (mean +/- s.d.) compared with a mid-cycle volume of 0.49 +/- 0.29 ml. Later in the breeding season, the flow rates were lower, but showed the same trend (0.91 +/- 0.24 ml at the peak and 0.25 +/- 0.18 ml 7 days later). The total amount of protein secreted by the oviduct each day increased 2-4-fold around the time of oestrus, with higher levels in mid-season ewes. When oviducal fluids were fractionated by SDS electrophoresis, a novel glycoprotein, subunit size of Mr 80-90 000 was identified in samples for 3-6 days of each cycle, coinciding with the period of high fluid flow rate. This protein first appeared in the oviducal fluid on the day of oestrus or the following day and it represented 1 of the 2 major glycoproteins in oviducal fluid as assessed by periodic acid-Schiff (PAS) staining. A PAS-positive protein (Mr 80-90 000) was also detected in fluid taken after oestrus on native highly cross-linked gradient gels after electrophoresis at pH 3.1 but not at pH 8.3. Both gradient gel systems showed an increase in high molecular weight material (Mr greater than 10(6] in fluid taken soon after oestrus.

Treatment of ewes at different stages of pregnancy with epidermal growth factor: effects on wool growth and plasma concentrations of growth hormone, prolactin, placental lactogen and thyroxine and on foetal development

Pregnant ewes at 57, 75 and greater than or equal to 101 days of gestation were infused with approximately 3 mg of epidermal growth factor (EGF) for a period of 24-28 h. The strength of attachment of the wool fibres to the skin became progressively reduced during the week following treatment. After 3 weeks, the mean forces required to pluck staples had declined to between 10 and 30% of the pre-infusion measurements and the fleeces were able to be removed easily by hand. Increases in growth hormone and placental lactogen occurred in plasma of ewes during EGF treatment. Prolactin was not affected by EGF but circulating levels of thyroxine declined. The concentrations of these hormones returned to approximate pretreatment values within 24 h of the end of infusion. EGF treatment at the dose levels used did not appear to significantly affect the development or viability of the foetus.

In vitro properties of diffuse cytoplasmic esterase-positive canine mononuclear leukocytes

Depletion of cytoplasmic esterase-positive canine peripheral blood monocytes from mononuclear cell suspensions was attempted using plastic adherence, carbonyl iron ingestion and/or Sephadex G-10 filtration. An esterase-positive, nonadherent, nonphagocytic subpopulation was identified and further characterized by the presence or absence of cell membrane receptors for the Fc portions of immunoglobulin and the activated third component of complement. The majority of these nonadherent cells lacked these receptors. The data suggests that canine peripheral blood monocytes are a heterogenous cell population.

Shared antigenic determinants between brain and thymus-derived lymphocytes in dogs

Canine anti-canine myelin, canine distemper convalescent, and control sera were tested for the presence of antilymphocyte antibodies in a complement-dependent microcytotoxicity assay. Sera were cytotoxic for CT 45-S cells, a canine origin thymic lymphoma, canine thymocytes, and phytomitogen-transformed canine peripheral blood lymphocytes. The cytotoxic effect was removed by absorption with canine white matter but not by absorption with galactocerebroside. The data suggests that the specificity of antimyelin and antilymphocyte antibodies is directed toward a common antigen (canine Thy-1). It is likely that, in canine distemper, these antibodies are produced following the lymphotropic phase of viral infection. The possibility that similar autoimmune phenomena observed in multiple sclerosis patients occur via an unrecognized infectious event in lymphoid tissues is raised.

The effect of thyrotrophin releasing hormone on pituitary and thyroid function in pre- and post-natal lambs

Thyrotrophin releasing hormone (TRH, 50 μg) was injected into chronically catheterized foetuses at various ages from 107 days gestation and into lambs up to 13 days post-partum. Changes in the concentrations of TSH, prolactin, T3 and T4 in plasma were measured by radioimmunoassay.

The initial concentration of TSH (1.2 ± 0.2, sem, ng/ml) and its increase in response to TRH was similar at all foetal ages tested. However, both pre-injection concentrations of prolactin in plasma and the magnitude of the response to TRH increased with foetal age. The responses in lambs up to 13 days old were greater than those in the foetuses.

The concentration of T4 was 6.3 μg/100 ml plasma in a 107 day-old foetus This had doubled by 128 days but declined again towards parturition. After TRH injection plasma T4 concentration increased in lambs, but showed little or no change in 113 and 137 day-old foetuses.

The concentration of T3 increased from 4–5 ng/100 ml plasma in 110–116 day-old foetuses to 40 ng/100 ml just prior to parturition. Values were high in the young lambs (362 ± 79 ng/ml) but declined with increasing age. There was no response to TRH up to 130 days gestation. A small response was obtained in a 137 day-old foetus while the concentration of T3 rose from 37 to 90 ng/100 ml in the 144 day-old foetus.

Injection of luteinizing hormone releasing hormone in quantities ranging from 25 to 150 μg caused no changes in circulating levels of TSH and prolactin.

It is concluded that although the foetal pituitary can respond to TRH by at least 107 days gestation, its maturity in relation to prolactin synthesis and release develops gradually, but most rapidly over the last 10 days of gestation. In comparison, the pituitary-thyroid system, known to be functioning before 107 days, may be insensitive to hypothalamic control. The evidence suggests that there is increased maturity of the thyroid gland with increasing foetal age, the concomitant rise in thyroid hormones initiating a negative feedback response.

Variations in plasma thyroxine concentrations throughout one year in penned sheep on a uniform feed intake

Plasma total thyroxine (T4) concentrations were measured by radioimmunoassay throughout one year in 10 sheep maintained indoors under natural light and consuming a constant amount of feed. Plasma T4 concentrations varied throughout the year, the highest and lowest values occurring in the spring and autumn months respectively. The mean of all observations was 5.4 +/- 0.1 microgram/dl. The changes observed did not appear to correlate with changes in ambient temperature, day length or with reported changes in wool growth.

Lymphocyte-associated immune responses to canine distemper and measles viruses in distemper-infected gnotobiotic dogs

Cellular immune responses of peripheral blood lymphocytes to canine distemper virus and measles virus were determined in vaccinated or infected gnotobiotic dogs, using the technique of syncytia inhibition. Cross-reactivity between viruses was detected in both groups of dogs. Peak responses in vaccinated dogs occurred 11 days after vaccination and declined to base-line levels by 3 weeks, whereas responses in infected dogs were present 30 days after inoculation. Fractionation experiments with peripheral blood lymphocytes indicated that synctia inhibition is probably mediated by T lymphocytes.

Plasma thyroid hormones and cholesterol in the newborn of genetically different types of cattle in a tropical environment

The patterns of plasma concentrations of thyroxine (T4), triiodothyronine (T3) and cholesterol were determined in tropically adapted (ZX) and temperate (SH) breeds of cattle in the first 6 days of their lives in a tropical environment. T4 concentrations were high at birth and fell to within normal adult values at 6 days of age. In contrast, plasma cholesterol levels were low at birth and increased daily to the highest values on day 6. T3 levels increased from birth to maximum values at 12 h after birth and then declined progressively. The T4/T3 molar ratios were high at birth and decreased to lower values on day 2. T4 and cholesterol levels were higher (p less than 0.001) in ZX than in SH calves, and in calves born in winter were higher (p less than 0.001) in females than in males. There were significant (p less than 0.001) animals within-breed differences in all parameters. The results are discussed with reference to the use of physiological and biochemical indices for the early selection of cattle suited to tropical conditions.

Evaluation of B-lymphocyte levels and functions in gnotobiotic dogs

Quantitative and qualitative aspects of B-lymphocyte functions in gnotobiotic dogs and conventional dogs were determined. Using 3 different methods to identify B-cells by surface markers and 3 different methods to measure immunoglobulins (eg, serum electorphoresis, immunoelectrophoresis, and radial immunodiffusion), it was determined that gnotobiotic dogs were B-cell deficient. Related studies, however, indicate that the capacity to develop humoral immune responses was unimpaired. It is presumed that lack of immunogenic stimulation within the gnotobiotic isolation units accounts for this observation.

The administration of flumethasone, by three different routes, its measurement in the plasma and some effects on wool growth in Merino wethers

Flumethasone was given to Merino wethers weighing 30-50 kg at rates of 0.62-1.35 mg/kg(0.75) by intravenous (experiments 1 and 2), intraruminal (experiment 4) and subcutaneous (experiment 5) routes over 8 days. In experiment 3, 1.2 mg flumethasone/kg(0.75) was given intravenously over 4, 5 or 6 days. The plasma concentration profiles showed concentrations in the order: intravenous greater than subcutaneous greater than intraruminal. Plasma concentration patterns usually were highest during the first 48 h of infusion followed by relatively stable values. This last feature was not evident in experiments when the rate of hormone infusion was increased. Estimates of the metabolic clearance rates for flumethasone in experiments 1, 2 and 5 were 200-700 ml/min during the equilibrium concentration periods. The effects of flumethasone on some aspects of wool growth revealed interactions between the routes of administration, the period of dosage and the rate of wool growth in the recipients. In experiments 1 and 2 intravenous infusion of 1.20-1.33 mg flumethasone/kg(0.75) caused the shedding of all wool fibres about 30 days after treatment. Some effects of dosing sheep with flumethasone at a time when wool growth was decreasing were also observed in experiment 2. Flumethasone given at a rate of 1.2 mg/kg(0.75) over 4, 5 or 6 days caused the shedding of only some wool fibres which were firmly retained on the sheep by the continuous fibres. Intraruminal and subcutaneous infusions of 0.62-1.35 mg flumethasone/kg(0.75) had similar results to the last in the majority of animals although in a few cases no discontinuity of wool fibres was observed. Recovery in wool growth was observed after treatment. Animals regained their pretreatment wool growth in experiments 1, 4 and 5 by 60 days after treatment and probably equalled at that time wool growth in controls. Recovery was retarded in some individuals in experiment 2 and in some groups in experiment 3. In experiment 1, 21 days wool growth was estimated to have been lost. Some aspects of complete versus partial shedding of wool fibres are discussed particularly with reference to wool harvesting. Some similarities in the appearance of fleeces of steroid-treated sheep and naturally shedding animals are also discussed. In some experiments, particularly when the infusion rate of flumethasone was increased (experiment 3), the sheep showed temporary but significant feed refusals during, but more commonly after, treatment. Speculative discussion as to the metabolic causes of this response is included.

Dexamethasone concentrations in ovine plasma during its intravenous infusion, its relation to the production of some endogenous hormones, and some of the effects on wool growth

Plasma concentrations of dexamethasone have been measured in sheep during an 8-day infusion of dexamethasone-21 phosphate. The dexamethasone concentration profiles generally revealed a reproducible pattern with three phases--a peak during the first 48 h infusion which was followed by falling concentrations during the next 5 days, and a small increase in dexamethasone concentration during the final 24 h infusion was not uncommon. The pattern of dexamethasone concentrations was retained when dosage was arranged in such a way as to infuse increasing quantities of hormonal analogue as infusion progressed. Aspects of the metabolism of the analogue are discussed. Endogenous thyroxine and cortisol were significantly depressed during infusion. In these experiments wool was completely shed in three out of four animals dosed at a rate of 8.5 mg dexamethasone/kg0.75. The recovery of wool growth to its pretreatment values occurred by about one month after infusion. The consumption of food and body weight increases were satisfactory during the post-infusion period.

Syncytia inhibition by immune lymphocytes: in vitro test for immunity to canine distemper

A simple and rapid (24-h) assay for peripheral blood lymphocyte-associated immunity to canine distemper virus (CDV) is described. The test is based upon leukocyte-associated inhibition of CDV-induced syncytia formation in Vero cells. The technique quantitates the response morphologically, thereby eliminating the requirement for release of radiolabeled compounds. Positive results were determined from specific-pathogen-free and gnotobiotic dogs exposed to CDV via hyperimmunization, vaccination with a modified live virus vaccine, and after virulent virus infection. Preinoculation lymphocytes and lymphocytes from non-immune dogs did not inhibit CDV-induced syncytia formation. Maximum responses were observed 7 to 21 days after initial exposure and declined thereafter. The method can be used to further investigate the role of immune lymphocytes in the recovery from CDV infection.

Plasma thyroxine concentrations in grazing sheep in several areas of Australia

Plasma thyroxine concentrations were measured by radioimmunoassay in plasma samples from 691 lactating ewes in 26 areas of New South Wales, Queensland, Western Australia and Tasmania. Sheep sampled in New South Wales and Tasmania had significantly lower plasma thyroxine values (4.0 and 4.3 microgram/100 ml respectively) than those sampled in Queensland and Western Australia (5.4 and 5.3 microgram/100 ml respectively). However, sheep in some districts in southern Queensland also had low plasma thyroxine values. The areas where sheep had low plasma thyroxine values correlate well with areas where goitre has been previously reported, both in man and in domestic animals. This suggests that measurement of plasma thyroxine is probably a valid empirical method of assessing the relative iodine deficiency of grazing sheep and further that sheep grazing substantial areas of New South Wales, Tasmania and to a lesser extent Queensland may have thyroid dysfunction of varying degrees of severity. These findings could have implications for animal production in these areas.

Pituitary and thyroidal responses to synthetic thyrotrophin releasing hormone in two breeds of cattle

The effect of thyrotrophin releasing hormone (TRH) on thyroid and pituitary function has been investigated as a possible aid to the early selection of cattle suited to tropical conditions. Two groups of six calves were used, one a shorthorn breed (SH) adapted to temperate conditions and the other an Africander cross (AX) selected for tropical climates. The dose and time responses of serum thyroid-stimulating hormone (TSH), tri-iodothyronine (T3), thyroxine (T4) and prolactin to single, repeated or multiple doses of TRH were measured by radioimmunoassay.

Levels of T3 and T4 before injection were lower in the SH than in the AX calves. After a single injection of TRH (0·4, 1, 2·5 or 5 μg/kg live weight) the percentage increase in T3 in the AX group was significantly lower than that in the SH group. No relationship was observed between the various doses and the magnitude of the response. There was, however, a negative correlation between values of T3 before injection and the maximum T3 response. The T4 : T3 molar ratio was also significantly lowered between 2·5 and 4·5 h after injection of TRH.

Changes in prolactin but not TSH concentrations were dependent upon the breed. After TRH injection, the initial increase in prolactin concentration was the same in both breeds but in the AX group the concentration then declined to values well below the pre-injection concentrations. In the SH group the prolactin concentrations returned to pre-injection levels.

When TRH was injected on 2 successive days the T3, T4 and TSH responses were less on the second day in both breeds. The prolactin response differed between breeds in a similar manner to that following a single injection of TRH.

Repeated hourly injections of increasing amounts of TRH for 4 h resulted in maximal increases of TSH after 2 h and of prolactin after 1 h. Despite continued injection the concentration of both hormones declined.

In the AX breed T3 and T4 concentrations continued to increase for 8 h after the first TRH injection whereas in the SH group no further increase in the concentrations of these hormones occurred after the first 4 h.

It is concluded that the information obtained by measuring resting serum T3 and T4 concentrations combined with changes in T3 and prolactin concentrations after TRH injection may aid in the early selection of cattle adapted to tropical conditions.

Changes in the T4/T3 molar ratio following thyrotropin releasing hormone injection in cattle

The injection of thyrotropin releasing hormone into cattle resulted in a rapid decrease in the T4/T3 molar ratio. 2 breeds of cattle, Shorthorn and Africander Cross were studied. The decrease in the T4/T3 molar ratio was significantly greater in the Shorthorn breed. It is concluded that acute stimulation of the thyroid gland with TRH results in enhanced release of both T3 and T4 and that T3 is discharged more rapidly than T4.

Absorption of 125I-labelled sheep growth hormone in single proximal tubules of the rat kidney

Techniques of kidney micropuncture and electron microscope autoradiography have been used to study the uptake of 125I-labelled sheep growth hormone (GH) in rat renal proximal tubules. After microperfusion of a proximal tubule with 125I-labelled GH, the transport of label by the tubular epithelium was studied autoradiographically at selected times up to 1 h. The sequential transfer of labelled material from tubule to microvilli, then to small and large apical vacuoles and finally to lysosomes followed the pattern of absorption that has been described for other proteins. Evidence of lysosomal degradation of the transported protein was obtained from studies in vitro; lysosomes isolated from the renal cortex rapidly converted 125I-labelled GH to products of lower molecular weight. In addition to the absorptive pathway through the intracellular vacuolar apparatus is appeared that there was also an alternative pathway, less well defined, whereby GH could be absorbed without being degraded.

Thyrotrophin concentrations in the plasma of cattle, sheep and foetal lambs as measured by radioimmunoassay

A radioimmunoassay technique for measuring the thyrotrophin (TSH) concentration of sheep and cattle plasma is described. The sensitivity of the assay allowed the measurement of 1-50 ng TSH/ml unextracted plasma. Cross-reaction with ovine luteinizing hormone, prolactin and growth hormone was very low. The average recovery of added TSH was 103 plus or minus 4-1 (S.E.M.)% and the between-assay coefficient of variation was 13-8%. The normal plasma TSH levels of sheep and cattle were approximately 2-5 ng/ml (5 mu. bovine TSH/100ml). Foetal sheep had plasma TSH concentrations of approximately 3-2 ng/ml during the last 20 days of gestation. Levels of TSH in the circulation decreased abruptly after hypophysectomy of the foetal lamb and a decline in the plasma thyroxine (T4) concentrations was also apparent within 24 h of the operation. However, thyroidectomy of adult and foetal sheep did not increase plasma TSH concentrations until almost all the T4 had been cleared from the circulation. The injection of T4 into thyroidectomized sheep rapidly reduced plasma TSH concentrations to normal values. However, the continued injection of T4 did not further reduce TSH concentration. The injection of T4 or triiodothyronine into normal sheep was also without effect on plasma TSH concentrations.