Can wear in total hip arthroplasties be assessed from radiographs?

The validity of wear measurements from total-hip radiographs was assessed using a wear simulator which consisted of a total hip prosthesis mounted on a Plexiglas orientation jig. Wear was mesured by a micrometer device and uni- and duoradiographic methods of wear measurement were used with a variety of acetabular cup orientations. In the initial calibration studies the duoradiographic technique proved to be more accurate. The source of the inaccuracies of the uniradiographic method was determined analytically by means of a geometrical model. Forty-inch or 72' source-to-object film-distances provided similar accuracy and the errors in wear measurement varied from --0.1 +/- 0.4 mm (2 S.D.) to 0 +/- 0.9 mm for wear magnitudes of 1 and 5 mm respectively, regardless of cup position. In subsequent calibration studies the previous radiographs were compiled to represent seven hypothetical patients at various stages of follow-up whose prostheses exhibited between 1 and 5 mm wear. Clinicians assessed the degree of wear, using both the uni- and duoradiographic techniques, under supervision but unaware of the true position and orientation of the wear track. The resulting errors were of the same order as the wear magnitudes being measured. The location of the measurements on the radiographs was then restricted to approximately the true wear axis but again the errors were so large that it was still impossible to make any valid wear assessments. The calibration runs were therefore terminated at this point and it was concluded that wear measurements could not be made from clinical radiographs.     

Porous-coated metal-backed patellar components in total knee replacement. A postmortem retrieval analysis

The use of porous-coated metal-backed patellar components to achieve consistent fixation by bone ingrowth and to provide relief of pain warrants serious scrutiny. We conducted a quantitative postmortem investigation of eleven consecutively retrieved components with use of high-resolution contact radiographs, electron microscopy, and histological analysis. The implants had been in situ for a mean (and standard deviation) of 45+/-36 months (range, one to eighty-four months). Analysis of the high-resolution contact radiographs revealed that a mean of 86+/-12 per cent (range, 61 to 100 per cent) of the porous coating was in contact with the host bone. Backscattered electron imaging showed that the mean volume fraction of bone ingrowth was 13+/-9 per cent (range, 0 to 30 per cent). No significant difference was detected, with the numbers available, between the volume fraction of the bone ingrowth measured in the porous coating and that of the host cancellous bone in the patellae.     

Thermal injury functionally alters bone marrow-derived macrophages: a study of monocyte-hepatocyte interactions

PURPOSE OF THE STUDY: The purpose of this study was to evaluate the results of the anterior cruciate ligament (A.C.L.) reconstruction according to two scoring systems (Arpege and IKDC), to analyse the influence of different factors on the results, to study the effect of a lateral extra-articular tenodesis, the morbidity of patellar tendon graft harvesting, and the advantage of arthroscopically assisted reconstruction. MATERIAL: Seventy nine patients, 17 to 39 years old (average 27 years), underwent an anterior cruciate ligament reconstruction for chronic instability, using a free bone-patellar tendon-bone graft. In 43 cases, a lateral extra-articular plasty was added (Lemaire's procedure). The reconstruction was arthroscopically assisted in 17 cases. Interval between initial injury and surgery was 24 months (2 months to 9 years and 7 months). The average follow-up was 2.5 years (range 1 to 18). METHOD: All patients were reviewed for evaluation with two scoring systems (Arpege and IKDC). Roentgenograms of both knees, including antero-posterior weight-bearing and lateral view, patellar view, dynamic radiographs, allowed evaluation of post-operative arthrosis and residual anterior laxity in extension. Fischer's test and chi square test were used for statistical evaluation. RESULTS: Using the Arpege CLAS system, functional results were excellent or good in 75.9 per cent of cases (excellent in 44.3 per cent, good in 31.6 per cent), fair in 15.2 per cent, poor in 8.9 per cent; according to the IKDC system, 65.8 per cent were excellent or good. 84.8 per cent of the patients were satisfied in Arpege system and 91.2 per cent in IKDC system. The pivot-shift test was negative in 86 per cent, equivocal in 7.6 per cent and positive in 6.4 per cent. The radiological Lachman's test (difference between control and affected knee) was 0-2 mm in 53.2 per cent, 3-5 mm in 39.2 per cent, 6-10 mm in 7.6 per cent, never greater than 10 mm. Antero-posterior weight-bearing radiographs were normal in 83.5 per cent, showed joint remodeling in 10.1 per cent pre-arthrosis in 6.3 per cent but no arthrosis. Functional results were not correlated with age at time of surgery, interval between initial injury and surgery, nor clinical Lachman's test. Competitive sportsmen had a better result (p = 0.001). Residual laxity in extension was correlated with lesions of medial meniscus (p = 0.035). Degenerative changes in femoro-tibial joint were correlated with residual laxity in extension (p = 0.019). There was no significative difference between A.C.L. reconstruction isolated or associated with lateral extra-articular tenodesis. Time to return to work was shorter for patients with arthroscopically assisted procedure (p = 0.067). DISCUSSION AND CONCLUSION: Functional results after A.C.L. reconstruction using a free bone-patellar tendon-bone graft are satisfactory and confirm the reliability of this procedure. Arpege CLAS and IKDC systems give comparable functional results, but IKDC evaluate anatomical results, residual laxity and degenerative changes of the joint, that constitute essential long-term pronostic factors. Morbidity of patellar tendon harvesting appears to be of short duration and largely reversible. Added lateral extra-articular tenodesis doesn't improve the results. Arthroscopically assisted procedure seems to allow a faster rehabilitation.     

Diagnosis of cranial cruciate ligament injury in dogs by tibial compression radiography

Stress radiographs were taken of 42 sound stifle joints, of five stifles with injuries other than cruciate disease, and of 72 stifles with surgically confirmed cranial cruciate damage. The stifles were also examined by the cranial drawer test. No false positive compression radiographs were obtained. In the 72 stifles with cranial cruciate damage, instability was diagnosed on the stressed view in all but two cases. The sensitivity of the radiographic tibial compression test was 97 per cent, compared with 86 per cent for the cranial drawer test; the specificities of the tests were 100 per cent and nearly 98 per cent, respectively.     

Before M.A.S.T.-I: analysis of the population of a participating center

After lumpectomy with axillary dissection and radiation therapy, there are numerous changes that occur to the breast that, if unrecognized as routine, post-treatment changes, can lead to inappropriate intervention by the physician. The purpose of this study is to evaluate the time required to achieve stable post-treatment mammographic and physical findings. One hundred twenty-three patients age 56.6 years with a mean tumor size of 15.9 +/- 8.2 mm were observed every 6 months with a mean change in scar size of 16.7 +/- 10.6 mm. A scar never developed in 27 per cent and completely resolved or decreased in 90 per cent. Calcifications developed in 16 per cent of the patients; 40 per cent in the scar, 60 per cent outside the scar. Recurrence developed in 2 per cent of the patients at a mean time of 53 months and was believed to be favorably influenced by cytologic evaluation of the resection margins at the time of tumor excision. Stabilization or resolution of the post-treatment changes occurred within 24 to 36 months. The conclusion is for careful surgical and radiologic follow-up with examinations, fine-needle aspirations, and meticulous mammograms guiding the need for biopsy.     

Two year followup of anterior and vertical atlantoaxial subluxation in ankylosing spondylitis

OBJECTIVE: To describe the clinical and radiological 2-yr followup of 22 patients with anterior atlantoaxial subluxation (AAS) from a prospective cohort of patients with ankylosing spondylitis. METHODS: The 2-yr assessment included a structured questionnaire for rheumatologic and neurologic complaints and lateral cervical radiographs in maximal flexion view. Initial and 2-yr radiographs were assessed blind to patient data. The course of anterior AAS was classified as unchanged (< 1 mm), progression (> or = 1 mm) or regression (> or = 1 mm) at 2 yrs compared with baseline. Vertical AAS was classified using the Sakaguchi-Kauppi method. Magnification factor was corrected using the ratio of C3 width. RESULTS: Anterior AAS was detected in 22 patients at baseline examination. Two patients also had vertical AAS; 86% were male. Mean age was 33 +/- 9 yrs and mean disease duration was 12 +/- 7 yrs. At followup, one patient had died of acquired immunodeficiency syndrome, 3 could not be reached, and 2 had undergone surgical fusion due to severe myelopathy and now showed complete neurological recovery. Of the remaining 16 patients, 7 (32%) showed progression and 9 (41%) showed no change in the C1-odontoid distance. Vertical AAS developed in one patient. After the 2-yr assessment, 3 additional patients had surgical fusion because of notable progression of AAS, despite absence of neurological signs. CONCLUSION: Anterior AAS progressed in a number of these patients in the 2 yrs following its detection, and with or without neurological signs, surgical management was thought appropriate in a considerable number of them.     

Pulmonary shunting during anesthesia with deliberate hypotension

Pulmonary shunting (Qs/Qt with FIO2 = 1) was measured in 18 anesthetized patients during deliberate hypotension. Hypotension was induced in 12 patients with sodium nitroprusside and light halothane anesthesia and in six others with deep halothane anesthesia and mechanical hyperventilation. Similar results were observed in the two groups. During the hypotensive period mean arterial pressure (MAP) was reduced to 49 +/- 2 torr, a 37 per cent decrease from the control level after the onset of operation and a 40 per cent decrease compared with the recovery level during closure of the wound. Qs/Qt, however, remained unchanged throughout the study: 5.2 +/- 0.9 per cent initially, 5.4 +/- 0.8 per cent during hypotension, and 4.7 +/- 0.5 per cent during recovery. It is concluded that pulmonary shunting need not develop during deliberate hypotension induced with either technique.     

Cerebral energy levels during trimethaphan-induced hypotension in the rat: effects of light versus deep halothane anesthesia

Hypotension may be expected to produce less perturbation of metabolism in the brain when cerebral metabolic rate is lowered by deep anesthesia. Male Wistar rats having unilateral carotidartery ligation were exposed to mean arterial pressure (MAP) of 40 torr for 22 min by an intravenous infusion of trimethaphan during anesthesia with halothane, 0.6 or 2 per cent, in oxygen. Cortical tissue metabolite levels on the side of the ligated carotid artery were more abnormal in rats receiving halothane, 0.6 per cent, than in those receiving halothane, 2 per cent. Values at halothane, 0.6 per cent, were adenosine triphosphate (ATP), 1.71 +/- 0.05 (+/-SEM) mumol/g, phosphocreatine (PCr) 1.97 +/- 0.07 mumol/g. and lactate 16.5 +/- 5.1 mumol/g; corresponding values at halothane, 2 per cent, were ATP 2.27 +/- 0.02, PCr 4.02 +/- 0.23, and lactate 4.75 +/- 0.9 mumol/g. ATP and PCr values were significiantly lower (P less than 0.05) and the lactate value was significantly higher with halothane, 0.6 per cent, than with halothane 2 per cent. Cerebral oxygen consumption decreased 47 per cent in rats anesthetized with halothane, 2 per cent. Preservation of cortical metabolite levels in deeply anesthetized animals suggests a protective effect of cerebral metabolic depression.     

Failure of intraoperatively customized non-porous femoral components inserted without cement in total hip arthroplasty

Seventy-four primary total hip arthroplasties were performed in sixty-eight patients between August 1990 and September 1991. Clinical assessments were made with use of the Harris hip score and, specifically, the pain component of that score. The preoperative radiographs were digitally quantified for calculation of the so-called canal-to-calcar ratio and the so-called cortical index. The postoperative radiographs were evaluated for the percentage of the cross-sectional area of the femoral canal that was occupied by the prosthesis; subsidence of the prosthesis; and adaptive osseous changes, including hypertrophic cortical remodeling, osteolysis, formation of sclerotic radiolucent lines around the prosthesis, and formation of a pedestal at the tip of the prosthesis. The indication for the arthroplasty was osteoarthrosis in fifty hips (68 per cent), avascular necrosis in fourteen (19 per cent), congenital dysplasia in six (8 per cent), and another diagnosis in four (5 per cent). The average duration of follow-up was thirty-one months (range, eleven to forty-six months). The average Harris hip score (and standard deviation) was 75 +/- 16.8 points (range, 29 to 100 points), and the average score for the pain component was 37 +/- 7.5 points (range, 0 to 44 points). The average canal-to-calcar ratio of the hips was 0.44 (range, 0.32 to 0.74), and the average cortical index was 0.54 (range, 0.33 to 0.66). The average subsidence of the component was 0.6 centimeter (range, 0.0 to 2.3 centimeters). The average fill of the canal was 100 per cent proximally, 97 per cent at the middle of the stem, and 92 per cent distally as measured on the anteroposterior radiographs made immediately postoperatively and 100, 95, and 90 per cent, respectively, as measured on the lateral radiographs. A failure occurred in twenty-one hips (28 per cent) in twenty-one patients, with an average time to failure of 21 +/- 13 months (range, one to forty-four months). The Kaplan-Meier survival estimate (and standard error) for this population was 0.45 +/- 0.11 (confidence interval, 0.67 to 0.23) at forty-four months. The average subsidence of the components that failed was 0.7 centimeter (range, 0.1 to 2.3 centimeters). There was no significant relationship between failure of the component and the age or sex of the patient, the diagnosis, or the side of the operation. Postoperative severity of pain (p = 0.09) or subsidence (p = 0.08) alone did not reach significance for predicting outcome. The Harris hip score alone (p = 0.05), the Harris hip score in combination with subsidence of the femoral component (p = 0.01), and the pain component of the Harris hip score in combination with subsidence of the femoral component (p = 0.01) were all significant for predicting outcome. No other measured radiographic variable was predictive of failure. Despite optimization of the fit of the component within the femoral canal and the percentage of the cross-sectional area of the femoral canal occupied by the component, the clinical results indicated a high rate of failure. Thus, these criteria are not the only requisites for stabilization of these femoral components without cement. On the basis of these data, we have discontinued the use of these intraoperatively customized, non-porous, smooth femoral prosthesis.     

Periodontal surgery of vertical bony defects with or without synthetic bioabsorbable barriers. 12-month results

The aim of the present study was to clinically and radiographically compare guided tissue regeneration (GTR) therapy with bioabsorbable polyglactin 910 barriers and conventional periodontal surgery in intrabony defects. In 26 patients with advanced periodontitis, 29 teeth exhibiting interproximal intrabony defects were treated; 15 by conventional periodontal surgery (control) and 14 by GTR (test). Before and 12 months after surgery, clinical parameters were assessed and standardized radiographs were taken. On the radiographs the distances from the cemento-enamel junction (CEJ) to the alveolar crest (AC), and the CEJ to the most apical extension of the bony defect (BD) were measured using a computer-assisted analyzing device (LMSRT). Twelve months after surgery, 24 patients with 27 lesions were available for examination. For both methods statistically significant (P < 0.001) probing depth (PD) reduction (mean +/- standard deviation) of -4.49 +/- 1.94 mm (n = 13, test) and -3.22 +/- 1.48 mm (n = 14, control), as well as clinical attachment gain (CAL-V) of 3.41 +/- 1.59 mm (test) and 2.07 +/- 1.10 mm (control), was observed. Radiographic changes of the distance CEJ to AC of -0.95 +/- 1.72 mm (n = 9, test), and -0.98 +/- 1.53 mm (n = 11, control) were not significant. A significant bony fill (distance CEJ-BD) of 1.05 +/- 1.22 mm was observed for the test group (P < 0.01); the 0.68 +/- 2.04 mm bony gain for the control group was not statistically significant. The PD reduction (P < 0.05) and attachment gain (P < 0.01) in the test group was statistically significantly more favorable than in the control group. Twelve months after surgery, statistically more favorable PD reduction and attachment gain was observed using polyglactin 910 barriers than compared to conventional flap surgery. Hence, the use of bioabsorbable barriers for therapy of intrabony defects may be recommended.     

Radiographic screening for breast carcinoma. III. Appearance of carcinoma and number of projections to be used at screening

The films of 117 patients with mammary carcinoma detected at population screening were reviewed. Sixteen per cent (19) of the women proved to have non-invasive and 43 per cent (50) small invasive carcinomas (diameter less than or equal to 10 mm). Calcifications were the dominating abnormality in 95 per cent of the non-invasive carcinomas, while a tumour mass was the most frequent abnormality in small invasive carcinomas. It was found that the appearance of small tumours may vary considerably from one projection to another and also on films in one and the same projection. Thus, approximately 20 per cent of small invasive carcinomas were either not visible or equivocal in one of the two projections used at screening. The corresponding figure for larger invasive carcinomas (diameter greater than 10 mm) was approximately 7 per cent. It is concluded that films in two projections, preferably the craniocaudal and oblique, should be obtained at screening.     

Regenerative periodontal surgery with non-resorbable and biodegradable barriers: results after 24 months

The aim of the present study was to compare the effects of guided tissue regeneration (GTR) with non-resorbable (ePTFE) and biodegradable barriers (Polyglactin 910). 23 patients provided 29 pairs of similar contralateral periodontal defects (12 pairs of interproximal intrabony lesions, 11 pairs of degree II and 6 pairs of degree III furcation defects). Each defect was randomly assigned to treatment with either non-resorbable (control [c]) or biodegradable (test [t]) devices. At baseline, 6, 12, 18, and 24 months after surgery, clinical measurements (PlI, GI, PPD, PAL-V, PAL-H) were performed. Standardized radiographs were obtained at baseline 12 and 24 months postsurgically. On the radiographs, the linear distances from the cemento-enamel junction (CEJ) to the alveolar crest (AC) and from the CEJ to bottom of the bony defect (BD) were measured using a computer-assisted analysing method (LMSRT). Both treatments revealed a significant (p<0.05) PPD reduction [all defects: -2.97 +/- 1.90 mm (t), -2.21 +/- 1.73 mm (c); intrabony defects: -4.00 +/- 1.96 mm (t), -3.00 +/- 1.87 mm (c); degree II furcations: -2.67 +/- 0.97 mm (t), -2.08 +/- 1.54 mm (c)], PAL-V gain [all defects: 2.02 +/- 1.83 mm (t), 1.18 mm +/- 1.50 (c); intrabony defects: 3.45 +/- 1.48 mm (t), 1.95 +/- 1.64 mm (c); degree II furcations: 1.33 +/- 0.94 mm (t), 0.92 +/- 1.47 mm (c)], PAL-H gain [degree II furcations: 2.22 +/- 0.94 mm (t), 1.86 +/- 0.60 mm (c)], and radiographic changes [CEJ-AC: -0.56 +/- 1.98 mm (t), -0.06 +/- 1.19 mm (c); CEJ-BD: 2.10 +/- 1.92 mm (t), 1.24 +/- 2.04 mm (c)] after 24 months. For degree III furcations, neither statistically significant PPD reduction nor PAL-V gain was observed. Similar clinical and radiographic results were found 12 and 24 months after surgical treatment using either non-resorbable or biodegradable barriers. More favorable results concerning PAL-V gain in interproximal intrabony defects could be observed with biodegradable barriers after 24 months than using nonresorbable membranes. Whereas interproximal intrabony lesions and degree II furcation defects responded favorably to GTR therapy, through-and-through furcations must be looked upon as a contraindication for this regenerative technique. Based on the results of the present study, the use of biodegradable barriers in GTR may be recommended and, thereby, a surgical re-entry to remove nonresorbable barriers can be avoided.     

Postmortem analysis of bone growth into porous-coated acetabular components

Microradiography, backscattered electron microscopy, and histological analysis were used to conduct a quantitative postmortem study of seven consecutively retrieved anatomical porous replacement acetabular components that had been inserted during total hip arthroplasties. Screws had been used for the initial fixation of six components. The microradiographic analysis of all seven components showed that an average (and standard deviation) of 84 +/- 9 per cent (range, 72 to 93 per cent) of the porous coating was in direct apposition to the periprosthetic bone. The backscattered electron images demonstrated that an average of 12 +/- 6 per cent (range, 4 to 21 per cent) of the space available in the porous coating was occupied by ingrown bone. The amount of bone ingrowth was not significantly different among the three zones delineated by DeLee and Charnley. Uniformity of bone growth into the porous coating suggests that the preferential loading that occurs in the superior region did not differentially affect the bone ingrowth. The present study showed that consistent bone growth into anatomical porous replacement acetabular components can be achieved.     

Transmission ionization chambers for measurements of air collision kerma integrated over beam area. Factors limiting the accuracy of calibration

Kerma-area product meters (KAP meters) are frequently used in diagnostic radiology to measure the integral of air-collision kerma over an area A (integral of A Kc,air dA) perpendicular to the x-ray beam. In this work, a precise method for calibrating a KAP meter to measure integral of A Kc,air dA is described and calibration factors determined for a broad range of tube potentials (40-200 kV). The integral is determined using a large number of TL dosimeters spread over and outside the nominal field area defined as the area within 50% of maximum Kc,air. The method is compared to a simplified calibration method which approximates the integral by multiplying the kerma in the centre of the field by the nominal field area Anom. While the calibration factor using the precise method is independent of field area and distance from the source, that using the simplified method depends on both. This can be accounted for by field inhomogeneities caused by the heel effect, extrafocal radiation and scattered radiation from the KAP meter. The deviations between the calibration factors were as large as +/- 15% for collimator apertures of 5-100 cm2 and distances from the source of 50-160 cm. The uncertainty in the calibration factor using the precise method was carefully evaluated and the expanded relative uncertainty estimated to be +/- 3% with a confidence level of 95%.     

Long-term efficacy of cyclical etidronate therapy in postmenopausal osteoporosis

Sixty-two women (mean age 68.7 +/- 0.9 yr) with postmenopausal spinal osteoporosis were treated with cyclical etidronate therapy (400 mg for 2 weeks alternating with 12 weeks of 1 gm elemental calcium and 400 IU Vitamin D3) for a minimum of 2 yr. Bone mineral density (BMD) of the lumbar spine (g/cm2) increased significantly (p < 0.0001) after yr 1 (4.1 +/- 0.5 per cent) and yr 2 compared with yr 1 (2.2 +/- 0.5 per cent). The response rate was 89 per cent after yr 1 and 84 per cent after yr 2. BMD of the hip (30 patients) increased by 1.5 +/- 0.9 per cent after yr 1 and 5.5 +/- 1.1 per cent (p < 0.0001) after yr 2 when compared with baseline. The response rate was 63 per cent after yr 1 and 80 per cent after yr 2. Smaller numbers of patients continued with treatment up to 4 yr with no adverse long-term effects.     

Fracture resistance of complex amalgam restorations

We surveyed the clinical presentation, initial management and subsequent course of a prospectively registered cohort of 60 children with insulin-dependent diabetes mellitus (IDDM) diagnosed before age 15 years in the Sultanate of Oman between January 1990 and December 1993. Clinical details from the time of diagnosis were available on all the children. At diagnosis 9 (15 per cent) presented with severe ketoacidosis (DKA) with pH less than 7.1 or plasma bicarbonate less than 10 mmol/l, and 16 (27 per cent) had mild to moderate ketoacidosis with pH 7.1-7.35 or plasma bicarbonate 10-18 mmol/l. During DKA electrolyte disturbances included: hypokalemia (K < 3.5 mmol/l) 25 per cent), hyperkalemia (K > 5.5 mmol/l) (18 per cent) and hyponatremia (Na < 130 mmol/l) (40 per cent). Serum creatinine concentrations were high in 25 per cent of children with DKA. Within the first year of diagnosis, 17 of the 60 children (28 per cent) experienced symptomatic hypoglycaemia, which in six (10 per cent) led to one or more admissions. Re-admission for unstable glycaemic control, excluding acute hypoglycaemia occurred at least once in six children (10 per cent) within 1 year of diagnosis and in 10 (17 per cent) within 2 years. Statural growth velocity (GV) and GVSDS (6.9 +/- 0.85 cm/year and 0.75, respectively) were significantly higher in the group of children with good glycaemic control (HbA1C = 7.9 +/- 0.4 per cent) compared to those children (3.7 +/- 0.44 cm/ year and -1.6, respectively) with bad glycaemic control (HbA1C = 12.5 +/- 1.5 per cent). Insulin-like growth factor-I (IGF-I) concentrations were significantly higher (260 +/- 21 ng/ml) in the group with good glycemic control v. the group with bad control (149 +/- 15 ng/ml). In summary, greater public and medical awareness of the presenting features of diabetes in young children is needed to reduce the frequency of DKA at presentation, and improvement of patient and family education is necessary to reduce the incidence of DKA and hypoglycaemia in children with IDDM.     

Retinal damage by light: possible implication of singlet oxygen

Rabbits fed a diet containing 40 per cent casein, 15 per cent oleic acid and 45 per cent laboratory pellets developed glycoallodeoxycholic acid and glycodeoxycholic acid gallstones. The oral administration of kanamycin prevented allo bile acid stone formation in the oleic acid fed rabbit without leading to cholesterol gallstone formation. Kanamycin reduced the concentration of allodeoxycholic acid in the bile of oleic acid fed rabbits from 16.6+/-4.1 per cent of total bile acids to 1.1+/-1.1 per cent, with a reciprocal increase in deoxycholic acid concentration. The allodeoxycholate concentration was far below that found in control bile samples, 10.2+/-2.3 per cent. If the effect of kanamycin on the bile composition is by its antibiotic action, this eliminates the importance of a hepatic contribution to allodeoxycholate stone formation.     

Computerized axial tomography: estimation of spatial and density resolution capability

The spatial and density resolution capability of the EMI-Scanner device for computerized axial tomography has been determined in vitro. For density differences greater than +/-1 per cent the spatial resolution is 6 X 6 mm. For density differences of 3 per cent and greater the resolution is 3 X 3 mm. Density resolution is at least +/-1 per cent for objects greater than 1 cm. Preliminary data on in vitro measurement of X-ray linear attenuation coefficients in tissue biopsies and standard solutions are given, together with the early results of enhancement of tissue density differences in vivo. Implications of this new technique for an in vivo neuropathology are suggested.     

The key informant technique

The clinical outcome of 152 patients aged 65 years or over who were referred to the author's institute between August 1990 and August 1991 with certain specified gastrointestinal malignancies and acute, life-threatening abdominal conditions, were audited concurrently. Two groups were considered: patients aged 65-79 years and those over 80 years. The mortality rate within 30 days of surgery was 14 per cent in both age groups, although significantly fewer patients aged over 80 years (35 of 54) were considered suitable for surgery than in the 65-79 years age group (84 of 98) (0.01 > P > 0.001). Morbidity after operation and cost of treatment were not significantly different between the two groups. Two years after surgery 40 per cent of the patients aged over 80 years and 58 per cent of those aged 65-79 years were alive. Quality of life in these survivors was good with 85 per cent of those aged over 80 years living at home and 72 per cent fit enough to undertake light work.     

Effect of dietary chloride content on the elimination of bromide by dogs

The effect of dietary chloride content (0.2, 0.4 and 1.3 per cent chloride on a dry matter basis) on the disposition of a single oral dose of bromide (14 mg kg-1) was evaluated in normal beagles. Increasing the dietary chloride content from 0.2 to 1.3 per cent resulted in a significant decrease in the mean apparent elimination half-life from 69 +/- 22 days to 24 +/- 7 days. The mean area under the concentration curve (AUC) for dogs fed 1.3 per cent chloride was significantly smaller than the AUC for dogs fed 0.2 per cent chloride. Dietary chloride had no effect on the maximum serum concentrations (Cmax) or on the time (Tmax) to reach the maximum concentrations. The steady-state serum bromide concentrations predicted from the single dose data for daily doses of 14 mg kg-1 of bromide were significantly lower in dogs fed 1.3 per cent chloride (310 +/- 150 mg litre-1) than in dogs fed 0.2 per cent chloride (1950 +/- 1140 mg litre-1). The predicted mean daily doses of bromide necessary to maintain serum levels within the therapeutic range for dogs fed 1.3 per cent chloride (43 +/- 13 mg kg-1) were almost twice as high as the dose estimated for dogs fed 0.4 per cent chloride (22 +/- 3 mg kg-1) and nearly three times as high as the dose estimated for dogs fed 0.2 per cent chloride (15 +/- 4 mg kg-1). These differences were statistically significant (P = 0.002).