Syrian hamster convalescence from prototype SARS-CoV-2 confers measurable protection against the attenuated disease caused by the Omicron variant

The mutation profile of the SARS-CoV-2 Omicron (lineage BA.1) variant posed a concern for naturally acquired and vaccine-induced immunity. We investigated the ability of prior infection with an early SARS-CoV-2 ancestral isolate (Australia/VIC01/2020, VIC01) to protect against disease caused by BA.1. We established that BA.1 infection in naïve Syrian hamsters resulted in a less severe disease than a comparable dose of the ancestral virus, with fewer clinical signs including less weight loss. We present data to show that these clinical observations were almost absent in convalescent hamsters challenged with the same dose of BA.1 50 days after an initial infection with ancestral virus. These data provide evidence that convalescent immunity against ancestral SARS-CoV-2 is protective against BA.1 in the Syrian hamster model of infection. Comparison with published pre-clinical and clinical data supports consistency of the model and its predictive value for the outcome in humans. Further, the ability to detect protection against the less severe disease caused by BA.1 demonstrates continued value of the Syrian hamster model for evaluation of BA.1-specific countermeasures.

648. Urinary Tract-Associated Escherichia coli Bacteraemia Strains Are Genetically More Virulent than Those Originating From Non-urinary and Neutropaenic Infective Foci

Background

Escherichia coli is the leading cause of bacteremia with multi-drug-resistant strains proving increasingly problematic. Knowledge of the strain diversity associated with site-specific infections will inform the development of new preventative strategies, e.g. vaccines. We hypothesized that virulence factor (VF) scores of bacteremia strains from neutropenia patients with unknown infective foci (NPUIF—likely due to bowel translocation) would be lower than those from immunocompetent patients.

Methods

Immunocompetent (n = 49) and neutropaenic adults (n = 8) with E. coli bacteremia were prospectively enrolled and the focus of bacteremia determined. Neutropenia patients were enrolled only if there was no identifiable infective focus. Multi-locus sequence typing and VF score (31 known VFs included) data were derived in silico following whole-genome sequencing and the results compared between patient groups.

Results

Bacteremia strains from immunocompetent patients with urinary tract infective foci (UTI-foci) harbored significantly more VFs (median VF score 16, range 8–24) than strains from both immunocompetent patients with non-UTI-foci (10, 2–22, P = 0.006) and NPUIF (8, 3–13, P < 0.0001). VF scores of strains from non-UTI-foci were not significantly different to those from NPUIF (10, 2–22 vs. 8, 3–13, respectively. P = 0.28). Logistic regression analysis demonstrated that VF score (OR 1.21, 95% CIs 1.01–1.46, P = 0.039) and recurrent urinary tract infection/urinary tract infection (OR 12.82, 95% CIs 1.24–132.65, P = 0.032) were independent predictors of bacteremia secondary to UTI-foci vs. non-UTI-foci in immunocompetent patients. Hence, for every unit increase in VF score, the odds of a bacteremia strain originating from UTI-foci increased by 1.21. papA, papC, papE/F, papG, agn43, tia, iut, fyuA, kpsM and sat were significantly more prevalent amongst strains associated with UTI-foci vs. non-UTI-foci amongst immunocompetent patients. papC, papE/F, papG, agn43, tia, fyuA, hlyA, usp and clb were significantly more prevalent amongst UTI-foci- vs. NPUIF-associated strains.

Conclusion

UTI-associated E. coli bacteremia strains have distinct VF profiles from those originating from non-UTI-foci and NPUIF. Future vaccines must consider this diversity to ensure adequate coverage of strains associated with site-specific disease.

Disclosures

All authors: No reported disclosures.

Methods and problems in the measurement of body water and electrolyte pools with radionuclide tracers

With the possible exception of ECF, body electrolyte spaces and pools can be measured with fair accuracy and are useful in their proper experimental context. The use of improved tracer techniques and mathematical analysis to study transfer rates between pools and the physiological factors which influence these rates offer a promising means of further progress in this field.

An evaluation of thymidine phosphorylase as a means of preventing thymidine rescue from the thymidylate synthase inhibitor raltitrexed

The antitumour effect of thymidylate synthase inhibitors such as raltitrexed (RTX) may be reversed by salvage of thymidine (Thd). Since thymidine phosphorylase (TP) depletes Thd, the potential for tumour-selective depletion of Thd using antibody-mediated delivery of TP to tumours was investigated. In vitro studies demonstrated that 25 x 10(-3) units/ml TP depleted extracellular Thd (3 microM) and restored sensitivity to the growth inhibitory effects of RTX in Lovo and HT29 cell lines. Thymidine concentrations in xenograft tumours were inversely proportional to the activity of TP in the tumour, and the presence of a subcutaneous Lovo xenograft reduced plasma Thd concentrations from 0.92 +/- 0.07 to 0.37 +/- 0.04 microM. Intravenous administration of native TP enzyme depleted plasma Thd to 5 nM, but following rapid elimination of TP, plasma Thd returned to pretreatment values. There was no effect on tumour TP or Thd. Conjugation of TP to the A5B7 F(ab)2 antibody fragment, which targets carcinoembryonic antigen (CEA) expressed on colorectal cell-lines such as Lovo, did result in selective accumulation of TP in the tumour. However, there was no tumour-selective depletion of Thd and there did not appear to be any potential benefit of combining antibody-targeted TP with RTX.

Gastrointestinal calcium absorption and dietary calcium load: relationships with bone remodelling in vertebral osteoporosis

Patients with vertebral osteoporosis have a wide range of bone loss rates, bone remodelling rates and capacities for gastrointestinal (GI) calcium absorption. To test the hypothesis that variations in GI absorptive capacity determine rates of bone loss or remodelling, we have sought relationships between calcium absorption or vitamin D metabolite levels on the one hand and rates of cancellous and cortical bone loss (measured by serial quantitative computed tomography in the radius; n = 25) or indices of bone remodelling in tetracycline-prelabelled transiliac biopsies (n = 41) on the other, in a sequential untreated group. Calcium absorption (net and true) was measured in 18-day balances and by a two-isotope deconvolution method (fractional absorption and maximum absorption rate, MAR). There was no significant seasonal effect on any of these four measures of calcium absorption (variance ratio, F = 0.52-1.61, p > 0.1) or on 1,25-dihydroxyvitamin D levels (F = 0.13, p > 0.1; range 11-69 pg/ml), notwithstanding the expected seasonal effect on 25-hydroxyvitamin D levels (mean 18.7 ng/ml, zenith mid July, semi-amplitude 7.5 ng/ml; F = 6.82, p < 0.01). Neither this metabolite nor 1,25-dihydroxyvitamin D correlated with any index of calcium absorption (p > 0.1). No measure of calcium absorption (or intake) had a significant relationship with radial cortical or cancellous bone loss (p all > 0.1) but cancellous bone loss was associated with the rate of endogenous calcium excretion (r = 0.50, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of two different periods of weight-reduction on selected performance parameters in elite lightweight oarswomen

Six successful members of the British Women's Lightweight Rowing Team were assessed before and after two-month (1990) and four-month (1991) periods of weight-reduction controlled by reduced caloric intake, while engaged in their normal physical training. Fat free mass (FFM) was calculated from body weight (BW) by utilising total body potassium measurements. Maximal oxygen intake (VO2max), respiratory anaerobic threshold (Tvent), upper body anaerobic peak power (PP) and mean power (MP) outputs, and knee flexor (KF) and extensor (KE) isokinetic peak torques were among the physiological parameters assessed. No statistical differences were noted between the data obtained prior to the two weight-reduction periods, and both periods resulted in lower BW (p < 0.001) and FFM (p < 0.05); approximately 50% of the lost BW was FFM. At the end of the two-month weight-reduction period Tvent (p < 0.02) and KF (p < 0.02) decreased. In contrast, a similar BW loss during the four-month period was associated with higher VO2max (p < 0.01) and PP (p < 0.05) compared with values prior to weight reduction. Comparisons between the percentage changes pre to post BW loss showed that the longer weight-reduction period was associated with significantly improved VO2max (p < 0.01), Tvent (p < 0.005), PP (p < 0.05) and KF (p < 0.05). We conclude: a) the proportion (50%) of weight lost as FFM in the present elite rowers is higher than the suggested optimal figure of 22%, and b) compared to four months, 6-7% of BW loss over two months may adversely influence fitness-related parameters in international lightweight oarswomen.

Growth hormone treatment improves serum lipids and lipoproteins in adults with growth hormone deficiency

The effects of 6 months' treatment with recombinant human growth hormone (rhGH) on serum lipids and lipoproteins were assessed in 24 adult patients with GH deficiency in a double-blind, placebo-controlled trial. Compared with age-, weight-, and sex-matched controls, the patients had significantly higher serum concentrations of total cholesterol (P = .002), low-density lipoprotein (LDL) cholesterol (P < .001), apolipoprotein B ([apoB] P = .011), and triglyceride (P = .017), and lower concentrations of high-density lipoprotein (HDL) cholesterol (P < .001). The prevalence of elevated serum cholesterol, triglyceride, LDL cholesterol, and apo B levels was 39%, 26%, 39%, and 25%, respectively; 75% of patients had decreased concentrations of HDL cholesterol. Treatment with rhGH (0.07 U/kg daily) resulted in decreases in total cholesterol level (5.8 +/- 0.3 to 5.1 +/- 0.3 mmol.L-1 over 6 months; P = .01 compared with placebo), LDL cholesterol level (4.22 +/- 0.25 to 3.19 +/- 0.23 mmol.L-1; P = .0003), LDL:HDL cholesterol ratio (5.57 +/- 0.47 to 3.29 +/- 0.33; P = .03), apo B level (1.07 +/- 0.06 to 0.84 +/- 0.07 g.L-1; P = .003), and apo B: A-1 ratio (0.73 +/- 0.05 to 0.69 +/- 0.05; P = .01). HDL cholesterol and apo A-1 levels did not change following rhGH treatment. The changes in lipid and lipoprotein levels were not significantly related to changes in insulin, thyroid hormones, insulin-like growth factor-1 (IGF-1), or indices of adiposity.(ABSTRACT TRUNCATED AT 250 WORDS)

Physical activity as a determinant of bone conservation in the radial diaphysis in rheumatoid arthritis

OBJECTIVES

To determine if increasing physical activity is protective of diaphysial (cortical) bone mass

METHODS

Fifteen patients attending two rheumatology clinics who had developed seropositive or classical rheumatoid arthritis up to 26 months previously were studied prospectively for two to three years. Rates of loss (or gain) in bone mass in the radial diaphysis and the trabecular bone of the distal radius were measured by quantitative computed tomography, and in the spine by dual photon absorptiometry. Physical activity was assessed by the Framingham physical activity index. Disease activity was followed at three-monthly clinic visits at which the haemoglobin, erythrocyte sedimentation rate, and platelet count were measured. The urinary hydroxyproline to creatinine ratio and plasma osteocalcin were measured at the beginning and end of the observation period.

RESULTS

Eleven patients required treatment with disease modifying drugs but none was given corticosteroids. Those whose physical activity did not improve lost radial diaphysial bone at about 4% annually. There was, however, a statistically significant inverse relation, accounting for 48.5% of the variance, between bone loss at this site and improvement in physical activity as assessed by the Framingham index. The other two sites showed much weaker associations. Adjusting for indices of disease activity hardly affected the first relation. Three biochemical indices related to bone turnover showed weak tendencies to decrease with increasing physical activity.

CONCLUSIONS

Peripheral cortical bone, distant from inflamed joints, is conserved more successfully in patients who achieve higher levels of physical rehabilitation. This may have implications for avoiding long bone fractures later in the disease.

Biochemical prediction of changes in spinal bone mass in juvenile chronic (or rheumatoid) arthritis treated with glucocorticoids

OBJECTIVE

To identify biochemical predictors of spinal bone mineral growth and the development of spinal osteoporosis in children with juvenile chronic arthritis (JCA) treated with glucocorticoids.

METHODS

Bone mass measurements were made at 3 monthly intervals for one year in 31 children. At each visit, blood and urine were obtained for assessment of laboratory indices related to the acute phase response and bone remodelling rates. Assessments were also made of joint inflammation (simple joint count).

RESULTS

Plasma albumin and C-reactive protein (CRP) concentrations contributed independently of height velocity to the prediction of lumbar spinal bone mineral growth, but only when averaged over the year of observation. The simple joint count did not usefully predict spinal bone mineral changes in the individual patient, nor did any measured index normally related to bone turnover (plasma osteocalcin, 25 (OH) vitamin D, urinary hydroxyproline). Mean values of the simple joint count were predicted by mean CRP and CRP trends. Joint count trends were predicted by hemoglobin trends. None of these relationships, although statistically significant, was strong enough to predict individual outcomes precisely.

CONCLUSIONS

Failure of spinal bone mineral growth is related to failure of growth in height and weight but also to biochemical markers for the activation of the acute phase response. Failure of bone growth to correlate with increased hydroxyprolinuria or plasma osteocalcin concentrations may be attributed to the confounding effect of glucocorticoid treatment on plasma osteocalcin levels in children whose bone resorption is little changed from normal levels despite their reduced growth. Biochemical measurements are weak substitutes for bone densitometry in monitoring spinal growth in these children.

Deflazacort in juvenile chronic arthritis

Vertebral crush fracture associated with glucocorticoid therapy causes major morbidity in juvenile chronic arthritis (JCA). Deflazacort (DFZ) may have an advantage over prednisone (PRED) because of its alleged bone sparing properties. Of 34 children with JCA receiving more than 5 mg PRED/day, 31 completed a 1-year, double blind, randomized, comparative trial of DFZ and PRED. Patient characteristics at trial entry were well matched. DFZ and PRED were prescribed in equivalent amounts. DFZ achieved similar disease control to PRED, and was not associated with untoward effects. Joint counts, hematological indices and biochemical values did not differ between treatment groups initially or during the trial. Bone density trends (velocities) in the lumbar spine were measured using dual photon absorptiometry at 3-monthly intervals and trends in bone and soft tissue growth calculated. Lumbar spine bone growth correlated with indices of somatic growth, with wide ranges in each group. Co-variance analysis showed a significant advantage (p < 0.007) of DFZ over PRED when spinal bone density was compared to body surface area and weight. Children taking DFZ showed less weight gain but similar height gain to children taking PRED. Children with poor or no somatic growth showed significant lumbar bone loss only in the PRED group. Of the children originally treated with PRED; 11 were switched to DFZ after completing the double blind study. Data for 26 children treated with DFZ for 1 year were thus available and confirmed a significantly greater rate of spinal bone growth relative to somatic growth, p < 0.002.(ABSTRACT TRUNCATED AT 250 WORDS)

Human parathyroid peptide treatment of vertebral osteoporosis

Previous studies have shown that treatment with daily injections of human parathyroid peptide (hPTH) 1-34 increase axial cancellous bone mass partially at the expense of peripheral cortical bone. In the present work the same hPTH 1-34 regime given for 12 months has been combined with oestrogen or nandrolone therapy to control peripheral bone resorption. Spinal and iliac cancellous (but not cortical) bone increased by 40%-50% above initial values while no perceptible changes occurred in radial cortical or cancellous bone. The evidence of radiokinetic and histomorphometric studies performed before and in the last months of treatment suggested that bone remodeling had proceeded through a transient anabolic phase with increased activation, but that activation had become normal after 11-12 months in the cancellous bone of the ilium whereas it continued to be raised elsewhere in the skeleton. It is concluded that in combination with oestrogens, hPTH peptides given daily injections hold great promise for the treatment of patients with osteoporosis who have already lost substantial amounts of spinal cancellous bone.

Temporal variations in iliac trabecular bone formation in vertebral osteoporosis

The histologic heterogeneity of osteoporosis relative to normal controls has attracted great interest. There has been controversy as to whether patients with high turnover osteoporosis may convert to a normal or low turnover form, and vice versa. We have studied 44 patients over 12 years by dynamic histomorphometry and 85Sr kinetics+calcium balance performed within 60 days in 20 patients (Group 1) and 75-808 days apart in the remainder (Group 2). In the first group, the histologic tissue level bone formation rate (BFR/BV or BFR/BS) was predictive of the 85Sr measurements of bone formation (r = 0.66 P < 0.01). There was no statistically significant correlation in Group 2 and the regression coefficients were significantly different (P = 0.01). Periodic regression was used to determine if seasonal changes were responsible for this loss of correlation; none was found that was of statistical significance. No systematic changes with time in bone formation were found in Group 2 during the period of observation; nor were consistent secular changes detected when the data for both groups were examined according to procedure date. In conclusion, bone formation may change with time in postmenopausal osteoporosis. Evidence that these changes are systematic was not found and this has implications for the design of treatment studies.

Whole-body and site-specific bone remodelling in patients with previous femoral fractures: relationships between reduced physical activity, reduced bone mass and increased bone resorption

1. A new tracer method is described for the non-invasive measurement of bone formation in the proximal femur. The method is based on our previously described whole-body method using 85Sr as the tracer (Reeve, J., Hesp, R. & Wootton, R. Calcif. Tissue Res. 1976; 22, 191-206). It allows correction to be made for long-term exchange processes within the skeleton. 2. The method has been applied in a study of regional and whole-body bone formation in 12 rehabilitated patients who had previously suffered a fracture of the proximal femur. Twelve healthy control subjects were studied, who were selected for their good health and continued physical activity. The aim was to explore the relationship between bone formation and physical activity. 3. Bone formation was similar in the two groups, both regionally and in the whole body. Based on analyses of four cadaver specimens, bone formation in the proximal femur was about one and two-thirds times that in the whole skeleton when related to mass of calcium in the region of interest. 4. Whole-body bone resorption, estimated from five measurements per subject of hydroxyproline excretion in relation to creatinine excretion, was significantly higher in the fracture patients (P < 0.01, Wilcoxon's test). 5. Estimates of current physical activity (and immediate pre-fracture physical activity) were made with a newly devised questionnaire. Historical levels of physical activity (at ages 15-45 years) were determined with Astrom's questionnaire. No bone formation index correlated with any index of physical activity. Urinary hydroxyproline excretion correlated inversely both with current physical activity and historical physical activity (for both regression coefficients P < 0.01). 6. The results are discussed in the light of our current understanding of the control of bone remodelling by the discrete basic multicellular units of bone. The opportunity to study regional bone resorption by the additional use of serial dual X-ray absorptiometry of the same region will in future allow the direct monitoring of the effects of therapeutic interventions which have been designed to prevent contralateral hip fracture.

Spinal and somatic growth in patients with juvenile chronic arthritis treated for up to 2 years with deflazacort

We previously reported a double-blind controlled trial of Deflazacort vs Prednisone in patients with Juvenile Chronic Arthritis who had required corticosteroid therapy for at least one year. This paper presents further results on an additional 11 patients, making 26 altogether, who were treated for one year with deflazacort. Fourteen of these went on to a second year of deflazacort treatment. As previously reported, the relative rate of spinal bone mineral growth in the first year was greater for the spinal bone mineral content than for the body surface by about 70%. In the second year of treatment spinal bone mineral continued, with wide variations, to grow at the same or a very slightly greater rate. However, somatic growth recovered so that there was no significant difference between the relative growth rates in the spinal bone mineral and the body surface area in year 2 (P = 0.78). Deflazacort therapy appears to permit appropriate growth of the spine in relation to the rest of the body against a background of variable growth impairment due to the disease process and the treatment required to control it.

Regulation of iron absorption in iron loaded subjects with end stage renal disease: effects of treatment with recombinant human erythropoietin and reduction of iron stores

The effects on iron absorption of variation in erythroid activity, haemoglobin and iron stores were studied in six anaemic dialysis-dependent subjects in whom iron stores were increased from previous red cell transfusions. Gastrointestinal mucosal uptake and whole body retention of oral iron were measured at the beginning of the study, after starting treatment with recombinant erythropoietin (but before significant increase in haemoglobin), after partial correction of anaemia, after further reduction of iron stores by repeated phlebotomy, and when erythropoiesis decreased from the discontinuation of treatment with erythropoietin. Between successive measurements, valid comparisons were made in five subjects. Correction of anaemia decreased whole body retention of iron through decreased mucosal uptake (P = 0.032). Further reduction in iron stores through repeated phlebotomy whilst the increase in haemoglobin was maintained by treatment with erythropoietin, tended to increase whole body retention of iron through an increase in mucosal transfer (P = 0.010). With initial enhancement of erythropoiesis in anaemic iron-loaded subjects there was no change in any measured component of iron absorption. However, after correction of anaemia and reduction of iron stores, a decrease in erythropoiesis was associated with decreased whole body iron retention in all subjects through decreased mucosal transfer (P = 0.028). The data suggest that anaemia upregulates mucosal iron uptake, and that erythroid activity upregulates mucosal transfer but that this latter effect may be counter-balanced by iron overload which downregulates mucosal transfer.

Basal metabolic rate in adults with growth hormone deficiency and in patients with acromegaly: relationship with lean body mass, plasma insulin level and leucocyte sodium pump activity

1. The relationship of lean body mass, plasma insulin concentration and leucocyte active sodium transport with basal metabolic rate was investigated in 24 adults with growth hormone deficiency before and after treatment with recombinant human growth hormone and in 10 patients with untreated acromegaly. 2. Based on total-body potassium determined by whole-body 40K counting, patients with acromegaly had increased lean body mass, whereas lack of growth hormone was associated with decreased lean body mass. 3. By indirect calorimetry, patients with acromegaly had increased basal metabolic rates and patients with growth hormone deficiency had decreased values when expressed as percentages of values predicted from the WHO/FAO/UNU equations. Basal metabolic rate expressed in terms of lean body mass was similar in acromegaly and growth hormone deficiency, but was higher than normal in both patient groups. 4. The leucocyte ouabain-sensitive sodium efflux rate constant was decreased in both patients with acromegaly and patients with growth hormone deficiency, and there was no correlation with basal energy expenditure, fasting plasma insulin level or serum growth hormone level. 5. There was no increase in the sodium efflux rate constant in patients with growth hormone deficiency after 1 month on treatment with recombinant human growth hormone. 6. Apparent differences in basal metabolic rate in growth hormone deficiency and acromegaly are due to changes in lean body mass. Both adults with growth hormone deficiency and patients with acromegaly have increased energy expenditure, probably owing to changes in fuel metabolism which are not reflected in the leucocyte sodium pump activity.

Validation of a method of treating menorrhagia by endometrial ablation

Menstrual blood loss was measured by intravenous injection of radioactive iron (59Fe) and whole-body counting in 19 women complaining of menorrhagia due to dysfunctional bleeding. Fifteen patients were then treated by radiofrequency endometrial ablation, after which blood loss was re-measured. The majority of the patients were bleeding excessively before treatment (mean 281 (SD 156) ml per cycle averaged over two cycles, range 49-665 ml, n = 19). In the 15 treated patients, average blood loss was reduced to 52 (SD 39) ml per cycle and the mean reduction in blood loss was highly significant (P < 0.001). These quantitative data correlate well with the patients' subjective reports.

Bone remodelling does not decline after menopause in vertebral fracture osteoporosis

There is considerable current interest in whether activators of bone remodelling, such as IL-1 and other cytokines, are involved in the pathogenesis of osteoporosis. We have therefore studied indices relating to remodelling activation in 50 patients with postmenopausal vertebral osteoporosis and 12 with hip fracture osteoporosis in comparison with 25 age- and sex-matched controls. Because of uncertainty regarding the accuracy of current biochemical markers of bone formation with respect to the estimation of whole body rates of bone formation, a 85Sr-based radioisotopic method was used. This method was previously validated by comparison with data obtained after double in vivo labelling of transiliac biopsies taken nearly simultaneously. Bone resorption was estimated from urinary hydroxyproline data. Controls selected for their continued good health showed a progressive and statistically highly significant decline in indices of bone formation with time after menopause. No such decline was seen in the vertebral fracture patients (P less than 0.005). There were no hip fracture patients within 10 years of menopause so this statistical test could not be applied appropriately to them. The hydroxyproline data were consistent with the suggestion arising from the bone formation data that remodelling declines progressively after menopause in the controls but not in the vertebral fracture patients. The data also suggested that these two fracture groups were in more negative calcium balance than the controls, this being particularly marked in the hip fracture cases. Plasma osteocalcin data correlated moderately well with the kinetic measurements of bone formation. It is concluded that vertebral fracture osteoporosis is associated with prolongation of menopausal levels of bone remodelling which is inappropriate by comparison with healthy controls.

Histology of skeletal muscle in adults with GH deficiency: comparison with normal muscle and response to GH treatment

The histology of needle biopsy specimens of skeletal muscle from the vastus lateralis was quantitatively assessed in a group of adults with growth hormone (GH) deficiency, most of whom had hypopituitarism treated with conventional pituitary hormone replacement. The mean age of the 21 patients (16 males and 5 females) was 39 +/- 2 (SEM). Comparisons were made with age- and sex-matched controls following six months double-blind, placebo-controlled treatment with recombinant human GH (rhGH) in the GH-deficient patients. Before treatment, needle muscle biopsies from patients with GH deficiency showed mean type I and II fibre areas of 5,153 +/- 273 and 4,828 +/- 312 microns 2 respectively, which did not differ from the controls (4,482 +/- 306 and 4,699 +/- 310 microns 2). Percentages of type I fibres were similar in the two groups (47.2 +/- 2.5% in GH deficiency and 45.3 +/- 2.2% in controls). No difference in the variability of type I or II fibre areas was demonstrated between the groups. Correlations between the relative contribution to total fibre area by type I fibres (mean fibre area x percent) and maximal oxygen uptake (p = 0.006), and between type II fibres and quadriceps force (p = 0.035) were noted in GH-deficient adults before treatment. Following rhGH treatment, no change was noted in mean fibre areas, variability of fibre areas, or percentage of either fibre type.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular effects of growth hormone treatment in growth-hormone-deficient adults: stimulation of the renin-aldosterone system

1. In adult humans with growth hormone deficiency, treatment with growth hormone has recently been shown to have major anabolic effects and to improve exercise performance. The cardiovascular effects of growth hormone in adults with growth hormone deficiency were examined in 24 patients treated with recombinant human growth hormone (0.07 units/kg at night) in a double-blind, placebo-controlled trial lasting 6 months. 2. Compared with placebo, resting M-mode echocardiography showed increases in left ventricular end-diastolic dimension and stroke volume in the group treated with recombinant human growth hormone. No differences were noted between the groups with respect to left ventricular end-systolic dimension, fractional shortening, wall thicknesses or mean arterial blood pressure. Left ventricular myocardial mass increased in the group given recombinant human growth hormone. 3. The supine plasma renin activity was increased and remained elevated over the 6 months, whereas the plasma aldosterone concentration was unchanged, after treatment with recombinant human growth hormone. Clinical signs of sodium retention were evident during the first 3 months of treatment with recombinant human growth hormone. 4. We conclude that treatment with recombinant human growth hormone in adults with growth hormone deficiency resulted in small increases in left ventricular pre-load, due to the sodium-retaining action of growth hormone. Activation of the renin-aldosterone system was involved in such changes. Myocardial hypertrophy was observed without changes in mean arterial pressure, reflecting the anabolic action of growth hormone.

Randomized, double-blind trial of deflazacort versus prednisone in juvenile chronic (or rheumatoid) arthritis: a relatively bone-sparing effect of deflazacort

Thirty-four children with juvenile chronic (rheumatoid) arthritis were recruited to a randomized, double-blind study of deflazacort (an oxazolone derivative of prednisone) vs prednisone. All had been receiving glucocorticoid therapy for at least 1 year and required at least 5 mg/d of prednisolone (usually as 10 mg every 2 days). Thirty-one children completed the study. Bone density trends were measured in the spine by dual photon absorptiometry and in the forearm by single photon quantitative computed tomography at 3-monthly intervals. Trends (velocities) in bone and soft tissue growth were calculated. In the spine, bone growth correlated well with indices of soft tissue growth, but covariance analysis showed a significant advantage (P less than .007) of deflazacort when spinal bone mineral growth was compared to body surface area and weight. In part this was due to a temporary interruption in weight by children receiving deflazacort, whose gain in height was comparable with that of the prednisone group. Some children in both groups improved clinically and showed catch-up growth; in these children relative spinal bone mineral growth velocities were about twice those observed for height and weight. It is concluded that during the first year of deflazacort, their spinal bone mineral content at a level that was appropriate for their height and weight. Further observations are required to establish whether this advantage can be maintained subsequently. The anti-inflammatory effects of the two glucocorticoids appeared similar.

Iliac trabecular bone formation predicts radial trabecular bone density changes in type 1 osteoporosis

In 28 patients with idiopathic or postmenopausal type 1 (spinal crush fracture) osteoporosis, resorption indices and dynamic measurements of trabecular bone formation based on in vivo tetracycline labeling in 7.5 mm transiliac biopsies have been compared with trends in radial cortical and trabecular bone density measured with computed tomography. Positive correlations were observed between trabecular bone density trends in the radius and indices of bone formation in the ilium. These were improved when one of the two resorption indices was included with a formation index in bivariate regressions. Marked interindividual variations in radial bone density trends were also seen in cortical bone. These correlated poorly with trends in trabecular bone. Weak negative relationships between cortical bone trends and indices relating to bone formation and resorption were observed, but a positive association was seen with single-labeled surfaces on iliac trabeculae. If, as has been suggested, there are periodic variations in bone formation, the results suggest that axial and peripheral trabecular bone density trends are synchronized in osteoporosis, perhaps in response to systemic factors, such as circulating hormones.

Different training patterns and bone mineral density of the femoral shaft in elite, female athletes

The effects of sporting activity and of menstrual status on the bone mineral content of the femoral mid-shaft were investigated. The cohort consisted of 67 elite, female athletes comprising 21 runners, 36 rowers, and 10 dancers. Twenty five of these athletes were amenorrhoeic, 27 eumenorrhoeic, and 15 were taking the oral contraceptive. The bone mineral content was also measured in 13 eumenorrhoeic, sedentary women. The mean (95% confidence interval) bone mineral content in the runners was 1.51 (1.47 to 1.55) g/cm2, which was significantly higher than in the rowers, dancers, and sedentary controls whose values were 1.43 (1.40 to 1.47), 1.39 (1.33 to 1.45), and 1.40 (1.34 to 1.45) g/cm2 respectively. There was no significant difference in the bone mineral content between the amenorrhoeic, eumenorrhoeic, and oral contraceptive taking athletes. These results may have implications for devising exercise strategies to reduce the possibility of fractures in later life.

hPTH 1-34 treatment of osteoporosis with added hormone replacement therapy: biochemical, kinetic and histological responses

Twelve patients with vertebral fracture osteoporosis were recruited into a trial of treatment with hPTH 1-34 by daily injection for 1 year combined (from the 5th month) with an anti-resorptive agent (oestrogen, n = 9; nandrolone, n = 3). Treatment outcomes were monitored by biochemical and radiotracer measurements together with histomorphometry of transiliac biopsies before and at the end of treatment following double in vivo pre-labelling with demethylchlortetracycline. Indices of whole body bone formation, obtained from the analysis of 85Sr data, showed substantial increases (P less than 0.005) for all three indices measured) while biochemical (hydroxyproline) and kinetic measurements of bone resorption showed modest and equivocal changes only. As a result calcium balance improved. Gastrointestinal calcium absorption showed a tendency to improve, while urine calcium decreased; but these changes were statistically not significant except for radiocalcium absorption in the oestrogen treated subgroup. Histomorphometry revealed substantial increases in cancellous bone volume as reported previously with hPTH 1-34 given alone. However, iliac (as distinct from whole body) indices related to bone formation and resorption appeared to have returned towards pre-treatment values by the time of the second biopsy under the influence of the anti-resorptive agent given with the hPTH 1-34. It is confirmed that hPTH 1-34 therapy can increase iliac cancellous bone mass (as well as spinal cancellous bone mass as reported earlier) without a long-term increment in whole body bone resorption, providing the hPTH is combined with an anti-resorptive agent.

Treatment of type 1 Gaucher's disease affecting bone with aminohydroxypropylidene bisphosphonate (pamidronate)

Two patients with Type 1 (adult) Gaucher's disease and major skeletal involvement with multiple fractures have been treated with the second generation bisphosphonate pamidronate for extensive periods. There was evidence of an immediate reduction in bone resorption, with increased calcium absorption (delayed in Patient 1), improved calcium balance and maintained or improved bone density indices in the axial and peripheral skeleton. There was no evidence of immediate relapse on treatment cessation. No toxic effects of pamidronate treatment were identified and subjective skeletal pain diminished in both patients. Histomorphometry of transiliac bone biopsies obtained before the start of treatment, after double in vivo tetracycline labelling, represents one of the earliest reports of the quantitative findings in iliac bone invaded by Gaucher cells.

Quantitative measurement of faecal blood loss: comparison of radioisotopic and chemical analyses

Blood loss in faeces was assessed by three different methods in five patients with recurrent iron deficiency. In short term (12 day) studies chemical analysis of complete stool collections for haemderived porphyrins (HemoQuant) gave results closely correlated with those obtained by measuring stool loss of 51Cr-labelled red blood cells. Whole body counting for 59Fe was relatively insensitive to small blood losses but allowed losses to be followed up over longer periods. Chemical analysis of faecal porphyrins thus provides a satisfactory alternative to radioisotopic techniques in short term quantitation of faecal blood loss, while longer term whole body counting of 59Fe may still be appropriate in a few patients for the detection and quantification of intermittent blood losses.

Growth hormone treatment in growth hormone-deficient adults. I. Effects on muscle mass and strength

The effect of recombinant DNA human growth hormone (rhGH) treatment in adults with growth hormone (GH) deficiency was studied in 24 patients in a double-blind placebo-controlled trial. The dose was 0.07 U/kg body wt daily. After 6 mo of treatment, significant increases were noted in the rhGH group for total cross-sectional area of thigh muscle (+11.2 +/- 3.1 vs. -0.5 +/- 3.0 cm2; P = 0.015 vs. placebo) and quadriceps muscle (+4.1 +/- 0.8 vs. +0.4 +/- 1.2 cm2; P = 0.031) measured by computerized tomography. Strong correlations were noted between lean body mass (measured as total body potassium) and total thigh muscle area in normal and GH-deficient adults both before and after rhGH treatment. Strength of hip flexors (+1.25 +/- 0.27 vs. +0.25 +/- 0.12 z-scores; P = 0.004) and limb girdle muscles increased (P = 0.02) in the rhGH group. We conclude that 1) rhGH increases lean tissue and skeletal muscle mass in adults with human GH deficiency, 2) this suggests a role for GH in the regulation of body composition of adult humans, 3) the increase in strength of limb girdle muscles after rhGH treatment suggests that adults with GH deficiency may have a proximal myopathy, and 4) the failure to demonstrate an increase in strength in other muscle groups may require the study of larger numbers of patients.

Growth hormone treatment in growth hormone-deficient adults. II. Effects on exercise performance

Growth hormone (GH) treatment in adults with GH deficiency increases lean body mass and thigh muscle cross-sectional area. The functional significance of this was examined by incremental cycle ergometry in 24 GH-deficient adults treated in a double-blind placebo-controlled trial with recombinant DNA human GH (rhGH) for 6 mo (0.07 U/kg body wt daily). Compared with placebo, the rhGH group increased mean maximal O2 uptake (VO2max) (+406 +/- 71 vs. +133 +/- 84 ml/min; P = 0.016) and maximal power output (+24.6 +/- 4.3 vs. +9.7 +/- 4.8 W; P = 0.047), without differences in maximal heart rate or ventilation. Forced expiratory volume in 1 s, vital capacity, and corrected CO gas transfer were within normal limits and did not change with treatment. Mean predicted VO2max, based on height and age, increased from 78.9 to 96.0% in the rhGH group (compared with 78.5 and 85.0% for placebo; P = 0.036). The anaerobic ventilatory threshold increased in the rhGH group (+159 +/- 39 vs. +1 +/- 51 ml/min; P = 0.02). The improvement in VO2max was noted when expressed per kilogram body weight but not lean body mass or thigh muscle area. We conclude that rhGH treatment in adults with GH deficiency improves and normalizes maximal exercise performance and improves submaximal exercise performance and that these changes are related to increases in lean body mass and muscle mass. Improved cardiac output may also contribute to the effect of rhGH on exercise performance.

High indices of remodelling in iliac trabecular bone predict reduced forearm cortical bone mass indices in patients with proximal femoral fractures

To investigate whether high bone turnover could be a predictor of cortical bone loss and a candidate risk factor for fractures of the proximal femur, 33 7.5-mm transiliac biopsies taken at fracture fixation from 48 patients who participated in a study of potential risk factors have been quantitated. Twenty-four of the 33 patients made good recoveries and about 6 weeks postoperatively consented to bone densitometry of the forearm midshaft. Forearm bone density correlated negatively (r = 0.77, P = 0.001) with the surface of trabecular bone covered with osteoid, which in osteoporotic patients with crush fractures of the vertebrae was previously shown to relate both to rates of bone formation and resorption. An important minority of these femoral fracture patients appeared to be suffering from high rates of iliac trabecular bone resorption. Thus, high bone remodelling activity could lead to excessive cortical thinning. This has pathogenetic implications which may be clinically important.

Treatment of osteoporosis with human parathyroid peptide and observations on effect of sodium fluoride

OBJECTIVE

To evaluate the need for a randomised study of treatment of spinal osteoporosis with human parathyroid peptide in the secondary prevention of crush fractures; to study the effect of human parathyroid hormone peptide 1-34 plus sex hormones on vertebral body cancellous bone; and, separately, to determine the effect of relatively low doses of sodium fluoride plus calcium on spinal bone mineral density.

DESIGN

Open study of patients with primary or postmenopausal osteoporosis. All patients had serial bone densitometry of the spine by quantitative computed tomography and dual photon absorptiometry as well as serial densitometry of the radial midshaft (cortical) and radial distal (trabecular) bone by quantitative computed tomography. Changes in the spinal bone not forming the spongiosa of the vertebral bodies ("cortical" bone) were determined from the difference between the two axial measurements, after correction to the same units of measurement.

SETTING

Northwick Park Hospital and Medical Research Council Clinical Research Centre.

PATIENTS

24 Patients who fulfilled the conventional criteria for type 1 (vertebral) osteoporosis not secondary to recognised causes other than sex hormone deficiency and with at least one crush or wedge vertebral fracture and a spinal bone density (quantitative computed tomography) less than 80 mg/cm3 or two or more fractures. Twelve patients received human parathyroid peptide and 12 sodium fluoride; they were not randomised.

MAIN OUTCOME MEASURES

Trends in axial and peripheral bone mass values determined by linear, time dependent regression analyses.

RESULTS

The patients receiving the peptide showed a substantial increase in vertebral spongiosa (mean 25.6 mg/cm2 two years after the start of treatment). No significant changes were seen in spinal cortical or radial bone density. The patients receiving sodium fluoride showed roughly equal increases in cancellous and cortical bone over the same period (mean increase in vertebral spongiosa 16.1 mg/cm3). No significant changes were seen in radial bone.

CONCLUSIONS

Treatment of postmenopausal women with human parathyroid peptide selectively increases spinal cancellous bone density by amounts that may prove useful in secondary prevention. Peptide treatment should now be tested in a randomised study in which the important end point is prevention of fractures as the usefulness of sodium fluoride in this context is doubtful.

Rapid periarticular bone loss in rheumatoid arthritis. Possible promotion by normal circulating concentrations of parathyroid hormone or calcitriol (1,25-dihydroxyvitamin D3)

For approximately 2 years, bone loss was measured in women with early stages of rheumatoid arthritis (RA) and in control subjects, using serial computed tomography and dual photon absorptiometry. Rapid trabecular bone loss from the distal radius was observed in the RA patients but not the controls. The bone loss correlated with initial plasma levels of parathyroid hormone and 1,25-dihydroxyvitamin D3 (calcitriol) concentrations. It has been suggested that these humoral factors may interact with cytokines or other mediators produced in the adjacent wrist joint. Losses of the cortical bone of the radial midshaft and the lumbar spine were modest and were comparable in the 2 groups. Indices relating to both bone formation and bone resorption predicted bone loss at these 2 sites, but changes in the parathyroid hormone and calcitriol concentrations did not.

The effects of treatment with recombinant human growth hormone on body composition and metabolism in adults with growth hormone deficiency

In a double-blind, placebo-controlled trial, we studied the effects of six months of growth hormone replacement in 24 adults with growth hormone deficiency. Most of the patients had acquired growth hormone deficiency during adulthood as a consequence of treatment for pituitary tumors, and all were receiving appropriate thyroid, adrenal, and gonadal hormone replacement. The daily dose of recombinant human growth hormone (rhGH) was 0.07 U per kilogram of body weight, given subcutaneously at bedtime. The mean (+/- SE) plasma concentration of insulin-like growth factor I increased from 0.41 +/- 0.05 to 1.53 +/- 0.16 U per liter during rhGH treatment. Treatment with rhGH had no effect on body weight. The mean lean body mass, however, increased by 5.5 +/- 1.1 kg (P less than 0.0001), and the fat mass decreased by 5.7 +/- 0.9 kg (P less than 0.0001) in the group treated with growth hormone; neither changed significantly in the placebo group. The basal metabolic rate, measured at base line and after one and six months of rhGH administration, increased significantly; the respective values were 32.4 +/- 1.4, 37.2 +/- 2.2, and 34.4 +/- 1.6 kcal per kilogram of lean body mass per day (P less than 0.001 for both comparisons). Fasting plasma cholesterol levels were lower (P less than 0.05) in the rhGH-treated group than in the placebo group, whereas plasma triglyceride values were similar in the two groups throughout the study. We conclude that growth hormone has a role in the regulation of body composition in adults, probably through its anabolic and lipolytic actions.

The effect of a high protein diet on leucine and alanine turnover in acid maltase deficiency

Leucine and alanine production rate was measured in 5 patients with acid maltase deficiency in the postabsorptive state, following 6 months on a normal diet with placebo and 6 months on an isocaloric high protein diet (16-22% protein). Whole body leucine production rate, a measure of protein degradation, expressed in terms of lean body mass was significantly greater than in five control subjects. Following the high protein diet, leucine production rate was decreased in four of the five patients but this was not statistically significant. Alanine production rate expressed in terms of lean body mass was significantly greater than in control subjects. After the high protein diet, alanine production rate and concentration were significantly decreased (p less than 0.05). There were no significant improvements in any of the clinically relevant variables measured in these patients. It is possible that a larger increase in protein intake over a longer time period may have a clinical effect.

Muscle and bone in paraplegic patients, and the effect of functional electrical stimulation

1. Four paraplegic men volunteered for an exercise programme in which their paralysed quadriceps muscles were stimulated by means of computer-regulated electrical impulses applied through external electrodes. The first exercise regimen consisted of leg raising against a graded load, and during the second regimen exercise took the form of cycling on a modified bicycle ergometer. Each subject exercised five times weekly for 10 weeks during the first regimen and 32 weeks during the second regimen. 2. Whole-body protein turnover determined by L-[1-13C]leucine during feeding remained constant during both exercise regimens, when expressed either in terms of body weight or fat-free mass derived from measurements of total body potassium. 3. Quadriceps muscle protein synthetic rate increased during the study, from 0.0712 to 0.0985%/h (P less than 0.05), as did quadriceps muscle area assessed by computed tomography. 4. Bone mineral content for lumbar vertebrae was normal in all four patients, but for the femoral mid-shaft bone mineral content averaged only 66% of normal for three of the patients. Trabecular bone density in the distal tibia ranged from normal to 2% of normal for the men with the shortest and longest periods of disability, respectively. No changes in bone mineral content or bone density occurred during the exercise period.

Dietary intake of calcium and postmenopausal bone loss

The use of calcium supplements to prevent postmenopausal bone loss and hence osteoporosis is widespread, but the evidence for their efficacy, either alone or in combination with other treatments, is contradictory. Skeletal measurements and dietary intake of calcium were determined in 59 healthy postmenopausal women, most of whom were within five years of the menopause. No correlation was found between current intake of calcium and either total calcium in the body or the density of trabecular or cortical bone in the forearm or vertebral trabecular bone. Dietary intake of calcium did not influence the rate of postmenopausal bone loss in the 54 women who completed 12 months of active or placebo treatment. Even when extremes of calcium intake were examined no difference was found in bone measurements between the women with the highest and lowest intakes. The results of this study suggest that the bone density of women in the early menopause is not influenced by current dietary intake of calcium.

Reversible trabecular bone density loss following induced hypo-oestrogenism with the GnRH analogue buserelin in premenopausal women

Thirteen premenopausal women who each received 400 micrograms three times daily of intranasal buserelin for 6 months as treatment for endometriosis participated in this study. Cortical bone mineral content (BMC) in the mid-shaft of the right femur measured by dual photon densitometry, and trabecular bone density (TBD) in the lumbar vertebrae (L2-4) measured by quantitative computed tomography, were evaluated prior to, at the end of 6 months' buserelin treatment and after 6 months off treatment. Significant hypo-oestrogenism (P less than 0.001) was sustained during the period on treatment. The significant reduction in the mean lumbar vertebral TBD of 5.9% (P less than 0.02) observed at the end of treatment with buserelin was regained within 6 months following resumption of ovarian activity. There was a marginally significant (P = 0.07) reduction of only 0.9% in the mean femoral cortical BMC at the end of treatment. Six months after the end of treatment cortical BMC values were not significantly different from the pretreatment values. There was no significant correlation between the degree of hypo-oestrogenism and the corresponding change in vertebral TBD, (r = 0.20; P less than 0.10).

Skeletal blood flow, iliac histomorphometry, and strontium kinetics in osteoporosis: a relationship between blood flow and corrected apposition rate

In 20 untreated patients with idiopathic or postmenopausal osteoporosis, kinetic studies of skeletal blood flow (using 18F) and bone turnover (using 85Sr) were combined with dynamic histomorphometry performed on transiliac biopsies taken within 6 weeks of each other. In 8 patients the combined studies were repeated after treatment. A further 5 patients were studied only while receiving treatment. As expected, skeletal blood flow measured by 18F correlated with an index of 85Sr uptake into the exchangeable pools of bone. Additionally and independently, skeletal blood flow correlated with an index of the work rate of the osteoblasts in each multicellular unit of bone (the corrected apposition rate of Parfitt). These correlations were statistically significant in both the untreated patients (P less than 0.05) and the whole group (P less than 0.001). Further indices related to bone turnover at the level of the skeleton as a whole were significantly associated with skeletal blood flow only in the combined group.

The assessment of bone formation and bone resorption in osteoporosis: a comparison between tetracycline-based iliac histomorphometry and whole body 85Sr kinetics

Bone formation and resorption have been measured in patients with idiopathic osteoporosis by histomorphometry of 7.5-mm trephine biopsies and in the whole body by 85Sr radiotracer methodology and calcium balances. The studies were synchronized and most were preceded by double in vivo tetracycline labeling. Correlations between histological and kinetic bone formation indices were better when better when based on the extent of double tetracycline labels than on measurements of osteoid by visible light microscopy. Correction of the kinetic data for long-term exchange, using 5 months' serial whole body counting of retained 85Sr, improved the fit of the kinetic to the histological data. A statistical analysis of the measurement uncertainties showed that the residual scatter in the best correlations (between exchange-corrected bone formation rates and double-labeled osteoid surface indices) could be attributed to measurement imprecision alone. The exchange-corrected resorption rate correlated fairly well with iliac trabecular resorption surfaces, and using a volume referent rather than a surface referent for the histological index improved the statistical fit when patients with therapeutically accelerated bone turnover were included. A much better correlation was obtained by including osteoid volume acting as an independent predictor of bone resorption in a bivariate regression with a resorption surface index. The residual errors could then be accounted for by known measurement uncertainties. Whereas osteoid taking a double label closely predicted the kinetic rate of bone formation, further analysis suggested that osteoid that took no label or a single label was more closely related to bone resorption, presumably as a secondary result of the coupling of bone formation to bone resorption. The idea that continued bone loss in some patients is associated with defective osteoblastic bone formation is supported by the low rates found in some patients by both techniques. Heuristically these studies validate both in vivo tetracycline labeling for dynamic histomorphometry and corrections for long-term exchange in kinetic studies of bone formation, providing a quantitative framework for the design and analysis of future studies of bone remodeling in the osteoporoses.

Periodic courses of human 1-34 parathyroid peptide alternating with calcitriol paradoxically reduce bone remodelling in spinal osteoporosis

In an attempt to achieve an anabolic response in both axial and peripheral bone, we treated twelve patients with osteoporosis using human 1-34 parathyroid peptide given discontinuously. The peptide was given as seven daily subcutaneous injections followed by 21 days' treatment with 0.25 mg calcitriol orally. This regime was repeated cyclically for at least sixteen cycles, of which the first four were at a lower dose of hPTH 1-34 than used subsequently. The results of treatment were monitored by kinetic, densitometric, histomorphometric and biochemical studies performed before and during treatment. Two patients developed hPTH 1-34 binding in their plasma during treatment: this was presumed to be due to the development of antibodies. The remainder, instead of increasing their indices of bone turnover as judged by iliac bone histomorphometry, were found to have consistent reductions in trabecular resorption surfaces. The other indices of bone formation and resorption measured showed no change or comparable reductions. The small increases seen in total body calcium were consistent with 'in-filling' of deleted basic multicellular units (BMUs). Because there is no evidence that calcitriol alone causes comparable reductions in activation of bone remodelling in osteoporosis, interruption of treatment with hPTH 1-34 after 7 days may have led to a failure of the activation mechanism to proceed to the resorption stage, with a consequent overall reduction in remodelling activity. This type of treatment regime, with its calcitonin-like effect, might be effective in reducing net bone loss due to imbalance between bone formation and resorption at the BMU level, particularly in patients with increased numbers of BMUs ('high turnover' osteoporosis).(ABSTRACT TRUNCATED AT 250 WORDS)

Estimation of whole body bone resorption rate: a comparison of urinary total hydroxyproline excretion with two radioisotopic tracer methods in osteoporosis

In 37 female patients with primary osteoporosis, urinary hydroxyproline excretion, determined in 18 24-h consecutive complete urine collections was compared with two radioisotopic measurements of bone resorption rate measured simultaneously using 85Sr. A somewhat better fit was obtained when the kinetically determined bone resorption rate was corrected for long-term exchange processes within bone. Regression analysis showed that the intercept of the regression of hydroxyproline excretion on resorption rate, corrected or uncorrected for exchange, was significantly higher than zero at about 100 mumol/day. This is consistent with a substantial fraction of urinary hydroxyproline arising from non-bony sources. Fifteen paired studies were analysed and the results suggested that intra-individual variability in these relationships (when studies were separated by a year or more) were similar to inter-individual variability. We calculated the precision with which an estimate of bone resorption could be determined based on the calculated regressions. As a means of non-invasive quantitation of whole body bone resorption rate, the excretion rate of hydroxyproline, measured over 5 days, for example, appeared competitive with isotopic methods making no correction for exchange and relatively little worse than our exchange corrected method.

Regional and total skeletal measurements in the early postmenopause

In a cross-sectional study of 70 early postmenopausal women, regional bone measurements were compared with total body calcium (TBCa). Spinal and forearm trabecular bone were mainly related to age and time since menopause. In contrast, TBCa and forearm integral (cortical and trabecular) and cortical bone were unrelated to age, although the time since menopause also had some influence. Forearm integral and cortical bone measurements were quite well correlated with TBCa (r = 0.84 and 0.73, respectively, P less than 0.001). The correlation between spinal bone measurements and any of the forearm measurements, even purely trabecular bone, was weak (r less than 0.52, P less than 0.001). Our results show quite clearly that forearm bone measurements cannot be used to predict bone density in the vertebrae. Loss of ovarian function affects bone in general, and trabecular bone in particular. Bone measurements at specific anatomical sites are clearly necessary for studies of metabolic bone diseases and their response to treatment.

Trabecular and cortical bone in the radii of women with parathyroid adenomata: a greater trabecular deficit, with a preliminary assessment of recovery after parathyroidectomy

Radial bone mineral content (BMC) has been reported to be lower than normal in patients with hyperparathyroidism, but those measurements have been made with techniques which do not discriminate between trabecular and cortical bone. We have used a low radiation dose computed tomography technique to make differential measurements of trabecular and cortical bone in the radii of 18 out of 27 eligible female patients with surgically proven adenomata. Prior to parathyroidectomy there was a mean deficit of 40% (P less than 0.001) in trabecular bone density in the distal radius, and a deficit of 16% in cortical bone in the radius mid-shaft compared to normal values. Seventeen months after parathyroidectomy there was a small but significant increase in trabecular bone density in the distal radius in 13 of these patients, and no significant change in cortical bone. If these results represented the situation throughout the skeleton, it is possible that parathyroidectomy may provide some reduction in future risk of fracture in women with primary hyperparathyroidism.