Calibration of an on-line dual energy X-ray absorptiometer for estimating carcase composition in lamb at abattoir chain-speed.

This experiment assessed the ability of an on-line dual energy x-ray absorptiometer (DEXA) installed at a commercial abattoir to determine carcase composition at abattoir chain-speed. 607 lamb carcases from 7 slaughter groups were DEXA scanned and then scanned using computed tomography to determine the proportions of fat (CT fat%), lean (CT lean%), and bone (CT bone%). Data between slaughter groups were standardised relative to a synthetic phantom consisting of Nylon-6. Models were then trained within each dataset using hot carcase weight and DEXA value to predict CT composition, and then validated in the remaining datasets. Results from across-dataset validation tests demonstrated excellent precision for predicting CT fat%, with RMSE and R2 values of 1.32 and 0.89, compared to values of 1.69 and 0.69 for CT lean%, and 0.81 and 0.68 for CT bone% which had less precision. Accuracy across datasets was also robust, with average bias values of 0.66, 0.83, and 0.51 for CT fat%, lean%, and bone%.

Propensity to 'relapse' following exposure to cocaine cues is associated with the recruitment of specific thalamic and epithalamic nuclei.

The thalamus is considered an important interface between the ventral striatopallidum and the dorsal striatum, and may therefore contribute to compulsive drug-seeking behaviour. Recent evidence suggests that the paraventricular thalamus (PVT), a dorsal midline thalamic nucleus, and the mediodorsal thalamus (MD) are involved in drug self-administration and respond to drug-associated cues. At present, however, the role of these thalamic regions in mediating cue-induced reinstatement of cocaine-seeking is unclear. Similarly, the habenula complex, part of the epithalamus, has been implicated in nicotine self-administration and cue-induced reinstatement of heroin seeking, but the role of this region in cocaine reinstatement behaviour has received little attention. Rats (n=20) were trained to self-administer cocaine in the presence of discriminative stimuli associated with drug availability (S⁺) or drug non-availability (S⁻). Once a stable level of responding was reached, lever pressing was extinguished. Animals were then tested for reinstatement and sacrificed immediately following the presentation of either the S⁻ or S⁺ discriminative stimuli, and Fos-protein expression was assessed in thalamic and epithalamic regions. Interestingly, significant variation was observed in reinstatement behaviour, allowing a comparison between high-reinstating (HR), low-reinstating (LR) and control animals. Compared with LR animals, HR animals exhibited increased Fos-protein expression in the PVT, intermediodorsal thalamus and the medial and lateral divisions of the habenula. Our data provide evidence that activation of thalamic and epithalamic nuclei is associated with propensity to reinstate to cocaine-seeking elicited by drug-related cues. We also build upon existing data highlighting the importance of the PVT in reinstatement behaviour.

Dietary vitamin K1 and stability of oral anticoagulation: proposal of a diet with constant vitamin K1 content.

Case reports cited in Medline or Biological Abstracts (1966-1996) were reviewed to evaluate the impact of vitamin K1 dietary intake on the stability of anticoagulant control in patients using coumarin derivatives. Reported nutrient-drug interactions cannot always be explained by the vitamin K1 content of the food items. However, metabolic data indicate that a consistent dietary intake of vitamin K is important to attain a daily equilibrium in vitamin K status. We report a diet that provides a stable intake of vitamin K1 equivalent to the current U.S. Recommended Dietary Allowance, using food composition data derived from high-performance liquid chromatography. Inconsistencies in the published literature indicate that prospective clinical studies should be undertaken to clarify the putative dietary vitamin K1-coumarin interaction. The dietary guidelines reported here may be used in such studies.

Elderly women accommodate to a low-protein diet with losses of body cell mass, muscle function, and immune response.

A 9-wk study of adaptation to marginal protein intakes was conducted in 12 elderly women. Subjects were randomly assigned to two groups fed a weight-maintenance diet containing either 1.47 (low) or 2.94 (adequate) g protein.kg body cell mass-1.d-1 (0.45 and 0.92 g.kg body wt-1.d-1, respectively). Mean nitrogen balance in the low-protein group remained negative throughout the study. These subjects experienced significant losses in lean tissue, immune response, and muscle function. The adequate-protein group was in nitrogen balance throughout the study, without changes in lean tissue, and with improvements in immune response, serum immunoglobulins, albumin, total protein values, and muscle function. Thus, elderly women fed the low-protein diet accommodated to the diet by compromising functional capacity, whereas those fed the adequate diet maintained functional capacity.

Lipoprotein response to exercise training and a low-fat diet in older subjects with glucose intolerance.

The purpose of this study was to determine the effect of aerobic exercise training (Ex), a low-fat diet (LF, 19% fat), or combined interventions (LF-Ex) on lipoprotein cholesterol (LDL, HDL, and VLDL) and triglyceride (TG) concentrations in glucose-intolerant subjects while their weight was maintained. Baseline dietary fat and carbohydrate composition, body composition, body mass index, age, and lipoprotein cholesterol were not different among groups. Aerobic capacity increased in both exercise groups (P < 0.01) and remained unchanged in the LF group. Body composition was unaltered and change in body weight (kg) was small: Ex, -0.8 +/- 0.4, (P < 0.05); LF, +0.4 +/- 0.4; (NS); LF-Ex, -1.4 +/- 0.4 (P < 0.01). Exercise alone did not significantly affect lipoprotein cholesterol or TG concentrations. In LF and LF-Ex, respectively, decreases (P < 0.02) in total cholesterol (-0.66 +/- 0.24 and -0.42 +/- 0.21 mmol/L), HDL (-0.14 +/- 0.07 and -0.26 +/- 0.04), and LDL (-0.60 +/- 0.25 and -0.23 +/- 0.13) were seen after 12 wk, whereas VLDL and TG remained unchanged. Our data indicate that beneficial effects of exercise training on lipid indexes are not observed in subjects with impaired glucose tolerance on either an average US diet or a low-fat diet if substantial changes in weight or body composition do not occur.

The future of total hip replacement.

Postoperative infection and the possibility of a stable, long-term cement-bone interface have been chosen as the two most important aspects of the future of total hip replacement. An attempt has been made to rekindle enthusiasm for extreme sterility in the operating room environment and to combine this with antibiotic prophylaxis. Examples of perfect cement-bone interfaces, judged on radiologic data after 12 1/2 years, are presented, together with radiographs of four examples of acrylic cement in the femur after 20 and 21 years of load bearing.

Long-term results of low-friction arthroplasty.

Two long-term studies of total hip replacement, carried out at Wrightington Hospital, England, and already published in 1977 and illustrated in detail, have been presented in an abbreviated, and it is hoped, more readable form. The first of these studies averaged 13 years and the second 8.3 years, but the latter has been updated to a maximum period of 13 years by reference to hospital records of secondary operations. The failure rate of the first series was 1.5% and that of the updated second series now becomes 2.6%. Some suggestions are made to explain this difference.

Subsidence of the femoral prosthesis in total hip replacement in relation to the design of the stem.

A method is described of measuring radiological subsidence of a femoral prosthesis in relation to the femur after total hip arthroplasty. The method depends on measuring the distance from the tip of the femoral prosthesis to a fixed point in the bone. Subsidence after the use of a conventional design of femoral stem is compared with that after the use of a stem with a dorsal flange (Cobra). A significant reduction in the incidence and amount of subsidence was found when using the dorsal flange. There was also a notable absence of transverse fractures involving the cement near the tip of the stem, which occurred in 26 per cent of the cases using a conventional prosthesis.

Hydroxychloroquine in prophylaxis of pulmonary embolism following hip arthroplasty.

Two thousand one hundred and forty four patients received Plaquenil (hydroxychloroquine sulphate) prior to total hip arthroplasty; the drug was continued until the patient was fully mobile. Fatal emboli (confirmed by postmortem) occurred in 0.28% and non-fatal emboli (diagnosed clinically) occurred in 4.15%. This was a statistically significant improvement over the overall results of all previous prophylactic measures used in this unit. The results of Plaquenil are significantly better than the most effective agent previously used in this unit, namely, Dindevan (phenindione). There were no deaths and no serious gastrointestinal or genitourinary bleeding. Allergic rashes occurred in 18 patients (0.8%), temporary blurring of vision in 6 (0.3%), and minor gastrointestinal upsets, including nausea, vomiting and minor bleeding in 12 (0.6%).

Total hip replacement following infection in the opposite hip.

Total hip replacements without ensuing infection were performed in 31 patients in the presence of infection in the contralateral hip. Infection in the opposite hip was proved bacteriologically in the follow-up in 19 cases averaged 5 years (2 years 3 months to 10 years). In another 12 hips in the same circumstances, without positive bacteriological evidence of active infection on the opposite side, healing occurred without infection.

Low-friction arthroplasty for healed septic and tuberculous arthritis.

Forty hips, which had previously been the site of tuberculous or pyogenic arthritis and which had later developed a degenerative arthritis, were treated by low-friction arthroplasty some forty years after the original infection. The results suggest that, when healing of the primary infection has been followed by a long period of quiescence with acceptable function before the onset of degenerative change, the arthroplasty can be confidently expected to result in greatly improved function and that this improvement is long-lasting.

Low-friction arthroplasty after fracture-dislocations of the hip.

Sixty-six patients are presented who have had a total hip replacement by the Charnley low-friction technique after injuries of the hip, the majority of which were fracture-dislocations. The clinical results of the arthroplasties in this relatively young group of patients are shown to be very good. The selection of young patients for total hip replacement arthroplasty is discussed.

Changes in the upper femur after low friction arthroplasty.

In 169 low friction arthroplasties, an extension to 10 years of the radiological appearances, noted at 4 years after acrylic cement had been in the medullary cavity of the femur, there was no grossly visible evidence of deterioration. An increased number of femora showed hypertrophy with normal bone texture. The number showing atrophy remained the same at about 4.8%. Absorption of the medial neck of the femur averaged 5.5 mm over the whole study and was often preceded by small cystic areas. Evidence of demarcation of cement from the endosteal surface of the femur was absent in 66%. When demarcation did occur, in most cases it was confined to the tip or below the midlevel of the stem. In only 2.4% did it reach slightly above the midlevel. No tendency could be found for the radiological appearances of medial femoral neck absorption or cement demarcation to predominate in patients with lower grade levels of function. Improved techniques, by which more perfect fixation between cement and bone in the upper level of the prosthetic stem is achieved, may eliminate instances of loosening and localized bone erosion encountered elsewhere.

Eight year results of Charnley arthroplasties of the hip with special reference to the behavior of cement.

Five hundred and forty-seven total hip replacements by the Charnley technique during 1967 and 1968 have been studied for the quality of the late results. The average follow-up was 8.3 years. Mechanical failure at the cement-bone interface occurred in only 2.2% of cases. A search was specially directed towards evidence of incipient pathology at the bone-cement interface in the absence of any suspicion of clinical defect. This was found in 12% of cases but it is emphasized that the criteria were exceptionally rigorous and entirely radiological. Because the cement technology used at that time is now considered unsophisticated, mechanical failure of cement is a preventable condition. A previous report of socket migration in 9.5% of cases is not confirmed by the present survey of a more recent series of cases.

Socket wear in Charnley low friction arthroplasty of the hip.

Five hundred forty-seven Charnley hip arthroplasties were measured for wear radiographically after an average period of 8.3 years. The operations were performed in 1967 and 1968 and the average rate of wear was 0.07 mm per year. This is only half that recorded for the operations in 1963, 1964, and 1965. Clinical radiographic methods of measuring socket wear are valid provided that the socket is inserted with the wear marker not more than 10 degrees from the coronal plane. This can be estimated provided that radiopaque cement is used.