Loss of bone mineral of the hip and proximal tibia following rupture of the Achilles tendon

In a prospective uncontrolled study 12 patients suffering from a rupture of the Achilles tendon treated operatively with surgical repair and post-operative immobilization in a short plaster cast for 6 weeks had bilateral measurements of bone mineral content (BMC) of the proximal tibia and bone mineral density (BMD) of the femoral neck and greater trochanter. The measurements were performed by dual energy X-ray absorptiometry (DEXA) and scans were performed post-operatively within 7 days after the operation and with follow up after 6 weeks, 3, 6, and 12 months. In the operated legs, BMC of the proximal tibia showed a progressive decrease reaching a total bone loss of 6.4% (95%-CL: -10.6%; -2.3%) 1 year after the injury. Bone mineral density at the hip of the operated legs also decreased significantly and 1 year after the injury BMD was 2.5% (95%-CL: -5.5%; 0.5%) and 6.8% (95%-CL: -9.8%; -3.7%) below the initial value in, respectively, the femoral neck and greater trochanter. Patients with a previous Achilles tendon rupture must be considered to be some years ahead in their natural osteoporotic process of the bones of the affected legs, and an increased risk of osteoporotic fractures must be considered not to be only theoretical.

Serological investigation of Mycoplasma genitalium in infertile women

BACKGROUND

The role of Mycoplasma genitalium in the pathogenesis of pelvic inflammatory disease has not been characterized.

METHODS

Sera from 308 infertile women were investigated for antibodies to M. genitalium by immunoblotting. Women with tubal factor infertility (TFI) made up 132 of the patients, 67 of the women had an infertile male partner and 109 were infertile for unknown reasons.

RESULTS

Of the TFI patients 29 (22.0%) were seropositive to the major adhesin, MgPa, of M. genitalium versus 11 (6.3%) in the group of women with normal tubes. No cross-reactions between MgPa and P1 of the related Mycoplasma pneumoniae were found. Besides, MgPa positive sera were confirmed by immunoblotting using a cloned fragment of the C-terminal part of MgPa specific to M. genitalium. Chlamydia trachomatis is known to be able to cause infertility as a result of salpingitis. Therefore, the sera were tested against C. trachomatis using a commercial ELISA test. Seventy-five (56.8%) of the TFI patients were seropositive to C. trachomatis. Eight (27.6%) TFI patients seropositive to MgPa were negative to C. trachomatis.

CONCLUSIONS

This study indicates that M. genitalium may be an independent risk factor in the development of an inflammatory process leading to scarring of the uterine tubes in women and thereby causing infertility.

Cell type-specific differences in glycosaminoglycans modulate the biological activity of a heparin-binding peptide (RKRLQVQLSIRT) from the G domain of the laminin alpha1 chain

AG73 (RKRLQVQLSIRT), a peptide from the G domain of the laminin alpha1 chain, has diverse biological activities with different cell types. The heparan sulfate side chains of syndecan-1 on human salivary gland cells were previously identified as the cell surface ligand for AG73. We used homologous peptides from the other laminin alpha-chains (A2G73-A5G73) to determine whether the bioactivity of the AG73 sequence is conserved. Human salivary gland cells and a mouse melanoma cell line (B16F10) both bind to the peptides, but cell attachment was inhibited by glycosaminoglycans, modified heparin, and sized heparin fragments in a cell type-specific manner. In other assays, AG73, but not the homologous peptides, inhibited branching morphogenesis of salivary glands and B16F10 network formation on Matrigel. We identified residues critical for AG73 bioactivity using peptides with amino acid substitutions and truncations. Fewer residues were critical for inhibiting branching morphogenesis (XKXLXVXXXIRT) than those required to inhibit B16F10 network formation on Matrigel (N-terminal XXRLQVQLSIRT). In addition, surface plasmon resonance analysis identified the C-terminal IRT of the sequence to be important for heparin binding. Structure-based sequence alignment predicts AG73 in a beta-sheet with the N-terminal K (Lys(2)) and the C-terminal R (Arg(10)) on the surface of the G domain. In conclusion, we have determined that differences in cell surface glycosaminoglycans and differences in the amino acids in AG73 recognized by cells modulate the biological activity of the peptide and provide a mechanism to explain its cell-specific activities.

A unique sequence of the laminin alpha 3 G domain binds to heparin and promotes cell adhesion through syndecan-2 and -4

Laminin-5, consisting of the alpha 3, beta 3, and gamma 2 chains, is localized in the skin basement membrane and supports the structural stability of the epidermo-dermal linkage and regulates various cellular functions. The alpha chains of laminins have been shown to have various biological activities. In this study, we identified a sequence of the alpha 3 chain C-terminal globular domain (LG1-LG5 modules) required for both heparin binding and cell adhesion using recombinant proteins and synthetic peptides. We found that the LG3 and LG4 modules have activity for heparin binding and that LG4 has activity for cell adhesion. Studies with synthetic peptides delineated the A3G75aR sequence (NSFMALYLSKGR, residues 1412--1423) within LG4 as a major site for both heparin and cell binding. Substitution mutations in LG4 and A3G75aR identified the Lys and Arg of the A3G75aR sequence as critical for these activities. Cell adhesion to LG4 and A3G75aR was inhibited by heparitinase I treatment of cells, suggesting that cell binding to the A3G75aR site was mediated by cell surface heparan sulfate proteoglycans. We showed by affinity chromatography that syndecan-2 from fibroblasts bound to LG4. Solid-phase assays confirmed that syndecan-2 interacted with the A3G75aR peptide sequence. Stably transfected 293T cells with expression vectors for syndecan-2 and -4, but not glypican-1, specifically adhered to LG4 and A3G75aR. These results indicate that the A3G75aR sequence within the laminin alpha 3 LG4 module is responsible for cell adhesion and suggest that syndecan-2 and -4 mediate this activity.

Identification of cell-binding sites on the Laminin alpha 5 N-terminal domain by site-directed mutagenesis

The newly discovered laminin alpha(5) chain is a multidomain, extracellular matrix protein implicated in various biological functions such as the development of blood vessels and nerves. The N-terminal globular domain of the laminin alpha chains has an important role for biological activities through interactions with cell surface receptors. In this study, we identified residues that are critical for cell binding within the laminin alpha(5) N-terminal globular domain VI (approximately 270 residues) using site-directed mutagenesis and synthetic peptides. A recombinant protein of domain VI and the first four epidermal growth factor-like repeats of domain V, generated in a mammalian expression system, was highly active for HT-1080 cell binding, while a recombinant protein consisting of only the epidermal growth factor-like repeats showed no cell binding. By competition analysis with synthetic peptides for cell binding, we identified two sequences: S2, (123)GQVFHVAYVLIKF(135) and S6, (225)RDFTKATNIRLRFLR(239), within domain VI that inhibited cell binding to domain VI. Alanine substitution mutagenesis indicated that four residues (Tyr(130), Arg(225), Lys(229), and Arg(239)) within these two sequences are crucial for cell binding. Real-time heparin-binding kinetics of the domain VI mutants analyzed by surface plasmon resonance indicated that Arg(239) of S6 was critical for both heparin and cell binding. In addition, cell binding to domain VI was inhibited by heparin/heparan sulfate, which suggests an overlap of cell and heparin-binding sites. Furthermore, inhibition studies using integrin subunit monoclonal antibodies showed that integrin alpha(3)beta(1) was a major receptor for domain VI binding. Our results provide evidence that two sites spaced about 90 residues apart within the laminin alpha(5) chain N-terminal globular domain VI are critical for cell surface receptor binding.

Quantitative ultrasound image analysis of the supraspinatus muscle

OBJECTIVE

To develop and validate a method, based on quantitative ultrasound image analysis, to objectively analyse and characterize the ultrasound images of m. supraspinatus.

DESIGN

Quantitative ultrasonography was performed on the supraspinatus muscle of 14 healthy subjects.

METHODS

A computerized analysis using first-order grey-scale statistics to evaluate the muscle tissue composition was developed and validated.

RESULTS

Data from one scanning site were not representative for the whole muscle due to muscle inhomogenity. Using first-order grey-scale statistics the scanning direction was of no importance. By using a scanning session consisting of three different scanning sites along the muscle in two directions, longitudinally and transversely, to characterize the tissue composition of the muscle, a high day-to-day reproducibility was obtained.

CONCLUSION

The described scanning session is a relatively sensitive and reproducible method for studying the muscle tissue composition. RelevanceQuantitative ultrasonography seems to be a potential clinical and occupational examination method to detect tissue composition of myalgic muscles compared to healthy muscles.

Dual energy X-ray absorptiometry in small rats with low bone mineral density

The feasibility of dual energy X-ray absorptiometry (DXA) using the Norland XR-26 Mark II bone densitometer for measurements of bone mineral content (BMC) and bone mineral density (BMD) in small rats was evaluated. Thirty-two young, isogenic, Lewis rats (weights from 119 g to 227 g) were used; normal rats (n = 7) and rats with low BMD obtained from three different vitamin D-depleted models (n = 25). DXA measurements were performed using the special software for small animals. Duplicate scans of excised femurs performed at 2 mm/second (pixel size of 0.5 mm x 0.5 mm) were very precise measurements with a coefficient of variation (CV) below 1.6% in animals with normal BMD; in rats with low BMD, the CV was significantly higher (P = 0.02-0.04), 7.8% and 4.4% for BMC and BMD, respectively. Regression analysis demonstrated that these measurements were related to the ash weight (R2 > 98.6%). The CV for measurements of the lumbar spine at 10 mm/second (pixel size 0.5 mm x 0.5 mm) was 2.6% and 2.2% for BMC and BMD, respectively in rats with normal BMD, and again higher (P = 0.03-0.14) in rats with low BMD, 7.3% and 4.7%, respectively, for BMC and BMD. Even though low CVs were obtained for total body duplicate scans (scan speed of 20 mm/second and a pixel size of 1.5 mm x 1.5 mm), the measurements were problematic for accuracy because of an overestimation of both BMC and the area of bone. Using these scan parameters the measurements of total body bone mineral could not be recommended in small rats with low BMD.

Identification of a major heparin and cell binding site in the LG4 module of the laminin alpha 5 chain

The G domain of the laminin alpha chains consists of five homologous G modules (LG1-5) and has been implicated in various biological functions. In this study, we identified an active site for cell and heparin binding within the laminin alpha5 G domain using recombinant proteins and synthetic peptides. Recombinant LG4, LG5, and LG4-5 modules were generated using a mammalian expression system. The LG4 and LG4-5 modules were highly active for cell binding, whereas the LG5 module alone showed only weak binding. Heparin inhibited cell binding to the LG4-5 module, whereas no inhibition was observed with EDTA or antibodies against the integrin beta(1) subunit. These results suggest that the LG4-5 module interacts with a cell surface receptor containing heparan sulfate but not with integrins. Solid-phase assays and surface plasmon resonance measurements demonstrated strong binding of the LG4 and LG4-5 modules to heparin with K(D) values in the nanomolar range, whereas a 16-fold lower value was determined for the LG5 module. Treatment with glycosidases demonstrated that N-linked carbohydrates on the LG5 module are complex-type oligosaccharides. The LG4-5 module, devoid of N-linked carbohydrates, exhibited similar binding kinetics toward heparin. Furthermore, cell binding was unaffected by removal of N-linked glycosylation. To localize active sites on the LG4 module, various synthetic peptides were used to compete with binding of the tandem module to heparin and cells. Peptide F4 (AGQWHRVSVRWG) inhibited binding, whereas a scrambled peptide of F4 failed to compete binding. Alanine replacements demonstrated that one arginine residue within F4 was important for cell and heparin binding. Our results suggest a critical role of the LG4 module for heparan sulfate-containing receptor binding within the laminin alpha5 chain.

Physiological response to submaximal isometric contractions of the paravertebral muscles

STUDY DESIGN

Brief (30-second) isometric trunk extensions at 5%, 20%, 40%, 60%, and 80% of maximal voluntary contraction (MVC) and 3 minutes of prolonged trunk extension (20% MVC) in erect position were studied in nine healthy male subjects.

OBJECTIVES

To investigate the intercorrelation between intramuscular pressure and tissue oxygenation of the paravertebral muscles during submaximal isometric contractions and further, to evaluate paravertebral electromyogram and intramuscular pressure as indicators of force development.

SUMMARY OF BACKGROUND DATA

Local physiologic responses to muscle contraction are incompletely understood.

METHODS

Relative oxygenation was monitored with noninvasive near-infrared spectroscopy, intramuscular pressure was measured with a transducer-tipped catheter, and surface electromyogram was monitored at three recording sites.

RESULTS

The root mean square amplitudes of the paravertebral electromyogram (L4, left and right; T12, right) and intramuscular pressure measured in the lumbar multifidus muscle at L4 increased with greater force development in a curvilinear manner. A significant decrease in the oxygenation of the lumbar paravertebral muscle in response to muscle contraction was found at an initial contraction level of 20% MVC. This corresponded to a paravertebral intramuscular pressure of 30-40 mm Hg. However, during prolonged trunk extension, no further decrease in tissue oxygenation was found compared with the tissue oxygenation level at the end of the brief contractions, indicating that homeostatic adjustments (mean blood pressure and heart rate) over time were sufficient to maintain paravertebral muscle oxygen levels.

CONCLUSION

At a threshold intramuscular pressure of 30-40 mm Hg during muscle contraction, oxygenation in the paravertebral muscles is significantly reduced. The effect of further increase in intramuscular pressure on tissue oxygenation over time may be compensated for by an increase in blood pressure and heart rate. Surface electromyogram amplitudes and intramuscular pressure can be used as indicators of paravertebral muscle force.

The plasma leptin concentration is closely associated with the body fat mass in nondiabetic uremic patients

Plasma leptin is associated with the body mass index and, more precisely, with the body fat mass. Plasma leptin has been found to be elevated in uremic patients. This study aimed at investigating the plasma leptin concentration and associations between plasma leptin, body fat mass, and glomerular filtration rate in nondiabetic predialysis uremic patients and in nondiabetic patients on chronic hemodialysis. Plasma leptin, body fat mass, and creatinine clearance were measured in 22 predialysis uremic patients, 18 hemodialysis patients, and 24 healthy control subjects. The logarithmically transformed plasma leptin concentration was closely associated with the body fat mass in all groups (r = 0.93, r = 0.83, and r = 0.72, respectively; p < 0.000001, < 0.000002 and p < 0.001, respectively). In predialysis uremic patients the plasma leptin concentration was slightly elevated as compared with controls 10.4 (3.1-59.5) ng/ml versus 5.4 (1.6-47.5) ng/ml (median and range in parentheses; p < 0. 05), whereas the plasma leptin concentration was normal in hemodialysis patients. Plasma leptin was not significantly associated with the creatinine clearance in predialysis patients. In conclusion; the glomerular filtration rate seemed to have a limited influence on the plasma leptin concentration in nondiabetic uremic subjects matched by body fat mass to controls. The plasma leptin concentration was closely associated with the body fat mass, and the leptin level might, therefore, be useful as an indicator of the fat mass in nondiabetic uremic patients.

Identification of metastasis-promoting sequences in the mouse laminin alpha 1 chain

Laminin-1, a major basement membrane matrix glycoprotein, enhances adhesion, migration, and metastasis of tumor cells. We have screened 208 overlapping synthetic peptides covering the short and long arms of mouse laminin alpha1 chain for their adhesion activity with B16-F10 mouse melanoma cells. Cell adhesion activity was determined using various amounts of peptides coated on plastic dishes and by measuring cell adhesion on peptide-conjugated Sepharose beads. Nineteen peptides showed B16-F10 cell adhesion activity. Three peptides, designated A-13, -24, and -208, showed the strongest attachment activity in the plate assay, whereas 4 peptides, A-13, -51, -99, and -112, demonstrated the strongest cell adhesion when conjugated to beads. The 19 peptides were tested in vivo for their effect on experimental pulmonary metastasis by B16-F10 cells. Four peptides, A-13, -51, -64, and -119, significantly enhanced metastasis, with A-13 showing the strongest dramatic enhancement. The four metastasis-promoting peptides also stimulated migration of B16-F10 cells in the Boyden chamber assay in vitro with A-13 being the most potent stimulator. In addition, the 4 peptides inhibited laminin-induced cell attachment and migration, which indicates that these four sequences are possible functional B16-F10 cell binding sites in laminin-1. All the four sequences are located on the globular domains of the short arm. Other peptides, including strong adhesion-active peptides, A-24, -99, -112, and a scrambled A-13 peptide, did not stimulate either migration or metastasis. Thus, laminin-1 has multiple active sites in the globular domains of the short arm which promote migration and metastasis of B16-F10 cells.

The muscular load on the lower back and shoulders due to lifting at different lifting heights and frequencies

The aim of the study was to investigate the muscular load on the lower back and shoulders and the circulatory load on employees at a post center during repetitive lifting of mail transport boxes. A mock-up was designed in the laboratory, a total of nine combinations of lifting height and frequency were studied. Surface EMG was recorded bisymmetrically from m. erector spinae (L3-level) and m. trapezius. The circulatory load was evaluated by measuring the heart rate. The results show a trade off between the low back and shoulders. The maximum load on the low back occurred at the low lifting height (363 and 54.4 cm) whereas the maximum load on the shoulders occurred at the high lifting height (144.9 and 163.0 cm).

Body composition by dual-energy X-ray absorptiometry in patients with Crohn's disease

BACKGROUND

To study body composition at the whole-body level in patients with Crohn's disease and a history of intestinal resection compared with healthy controls, we performed a cross-sectional study using dual-energy X-ray absorptiometry (DXA).

METHODS

Thirty-one patients, 13 men and 18 women, were included. They had a history of Crohn's disease for a mean period of 20 years (range, 4-45 years). All patients had undergone intestinal resections. The colon had been resected in 24 patients, and the mean length of the resected small intestine was 97 cm (range, 0-305 cm). At the time of investigation the Crohn's disease had been in remission for at least 24 months. Patients presented with significantly increased faecal volume and faecal fat excretion. A group of 69 women and 19 men were investigated with DXA and used as reference group. The fat-free mass (FFM), fat mass (FM), percentage fat mass (FM%), and total body mineral content (TBMC) were measured by DXA, and the results were expressed as a z-score.

RESULTS

The mean z-score of the body mass index (BMI) was significantly reduced to -0.35 (P=0.036). The FFM was significantly reduced with a mean z-score of -1.74 (P=0.0001). The FM was unchanged (z-score, 0.12; P=0.42). However, FM expressed as percentage of body weight was significantly increased, with a z-score of 0.88 (P=0.001). The TBMC was significantly decreased, with a mean z-score of -1.42 (P=0.0001). There was positive direct correlation between the BMI and TBMC z-scores. There was no correlation between malabsorption and body composition variables.

CONCLUSION

Patients with clinically quiescent Crohn's disease showed significant changes in body composition, with low BMI, significant loss of FFM, and unchanged FM. However, when expressed as percentage of body weight, FM was significantly increased. The TBMC was significantly reduced.

Long-term effects of intermittent oral alphacalcidol, calcium carbonate and low-calcium dialysis (1.25 mmol L-1) on secondary hyperparathyroidism in patients on continuous ambulatory peritoneal dialysis

OBJECTIVES

(i) To examine the effect of alphacalcidol [1 alpha(OH)D3] given as an oral dose twice weekly in combination with CaCO3 and low-calcium dialysis (1.25 mmol L-1) on the secondary hyperparathyroidism in continuous ambulatory peritoneal dialysis (CAPD). (ii) To examine the changes in peritoneal mass transfer for calcium, phosphorus, magnesium, lactate, creatinine, urea, glucose, pH and albumin after shift to low-calcium dialysis solution.

DESIGN

An open study in patients on CAPD.

SETTING

Renal division, Rigshospitalet, Copenhagen.

SUBJECTS

Thirty-nine patients were included and completed 12 weeks of treatment. Thirty of the patients completed 52 weeks of treatment. A peritoneal equilibrium test (PET) was performed in seven patients.

INTERVENTIONS

Following two sets of blood samples obtained as basal values the calcium concentration was reduced in the dialysis fluid from 1.75 mmol L-1 to 1.25 mmol L-1. Increasing doses of oral 1 alpha(OH)D3 were then administered under careful control of p-ionized calcium (p-Ca2+) and p-inorganic phosphate (p-P1). Blood samples were obtained every 2-4 weeks for 52 weeks. PET was performed using standard dialysis fluid and 1 week later using low-calcium dialysis fluid after a preceding overnight dwell. Two litres of glucose 22.7 mg mL-1 were used.

MAIN OUTCOME MEASURES

Intact parathyroid hormone (PTH), p-Ca2+, p-P1, doses of CaCO3, doses of 1 alpha(OH)D3, peritoneal mass transfer for calcium, inorganic phosphate, magnesium, lactate, creatinine, urea, glucose and albumin.

RESULTS

Thirty nine patients with initial PTH values 144 +/- 26 pg mL-1 were followed for 12 weeks and 30 patients for 52 weeks. A negative calcium balance was induced after shifting to low-calcium dialysis fluid. After 2 weeks of treatment a significant increase of PTH by approximately 60% and a small but significant decrease of p-Ca2+ was observed. After 12 weeks of treatment with increasing doses of 1 alpha(OH)D3 and CaCO3, PTH was again reduced to levels not significantly different from the initial values. After 52 weeks of treatment no deterioration of the secondary hyperparathyroidism was seen.

CONCLUSIONS

A calcium concentration of 1.25 mmol L-1 in the CAPD dialysate made it possible to reduce the amount of aluminium-containing phosphate binder, to increase the doses of CaCO3 and to use pulse oral 1 alpha(OH)D3 without causing severe hyper-calcaemia in the patients. After a short elevation of PTH, the PTH levels remained at normal or near normal levels and the long-term results clearly demonstrated that an aggravation of the secondary hyperparathyroidism could be inhibited.

Microalbuminuria as an early indicator of osteopenia in male insulin-dependent diabetic patients

Reduced bone mineral density (BMD), termed diabetic osteopenia, has been reported in patients with insulin-dependent (Type 1) diabetes mellitus (IDDM). To examine BMD in long-term IDDM patients with normal kidney function, but with different degrees of urinary albumin excretion rate (UAER), compared to that of patients with elevated plasma creatinine, 36 IDDM male patients (mean duration 27 years) were subdivided according to UAER (<30, 30-300, >300, >300 mg 24 h(-1) and plasma creatinine 0.120-0.350 mmol l(-1)) and 15 controls were recruited. BMD was measured by dual energy X-ray absorptiometry and UAER by enzyme linked immunosorbent assay. BMD was normal in IDDM patients with normal UAER and reduced in the femoral neck, the trochanter major, and the Wards triangle in patients with increased UAER (p < 0.01, p < 0.05, p < 0.02). BMD correlated to creatinine clearance in both cortical and cancellous bone sites (p < 0.001, p < 0.0001), and inversely to the levels of plasma PTH (p < 0.0005). We conclude that BMD is normal in long-term IDDM male patients with normal kidney function and normal UAER and reduced in patients with increased UAER. Diabetic osteopenia seems to be a progressive phenomenon related to diabetic nephropathy and associated with the decrease in creatinine clearance and with the resulting rise in plasma PTH.

Microalbuminuria as an early indicator of osteopenia in male insulin-dependent diabetic patients

Reduced bone mineral density (BMD), termed diabetic osteopenia, has been reported in patients with insulin-dependent (Type 1) diabetes mellitus (IDDM). To examine BMD in long-term IDDM patients with normal kidney function, but with different degrees of urinary albumin excretion rate (UAER), compared to that of patients with elevated plasma creatinine, 36 IDDM male patients (mean duration 27 years) were subdivided according to UAER (<30, 30-300, >300, >300 mg 24 h(-1) and plasma creatinine 0.120-0.350 mmol l(-1)) and 15 controls were recruited. BMD was measured by dual energy X-ray absorptiometry and UAER by enzyme linked immunosorbent assay. BMD was normal in IDDM patients with normal UAER and reduced in the femoral neck, the trochanter major, and the Wards triangle in patients with increased UAER (p < 0.01, p < 0.05, p < 0.02). BMD correlated to creatinine clearance in both cortical and cancellous bone sites (p < 0.001, p < 0.0001), and inversely to the levels of plasma PTH (p < 0.0005). We conclude that BMD is normal in long-term IDDM male patients with normal kidney function and normal UAER and reduced in patients with increased UAER. Diabetic osteopenia seems to be a progressive phenomenon related to diabetic nephropathy and associated with the decrease in creatinine clearance and with the resulting rise in plasma PTH.

Characterisation of bovine structure-specific recognition protein 1 (SSRP1) cDNA

A partial bovine SSRP1 (structure-specific recognition protein 1) cDNA has been isolated from a osteoblast cDNA library and sequenced. The bovine SSRP1 cDNA of 1870 bp encoding 460 amino acid residues showed 86% and 98% sequence identity with human SSRP1 at the DNA and protein level, respectively. Expression of SSRP1 mRNA was detected in many human tissues, with a particularly high level in kidney.

Inhibition of PTH secretion by interleukin-1 beta in bovine parathyroid glands in vitro is associated with an up-regulation of the calcium-sensing receptor mRNA

The principal regulator of parathyroid hormone (PTH) secretion is ionized calcium, but other factors are also known to modulate PTH secretion, such as vitamin D, estrogen, and recently inorganic phosphate. Interleukin-1 (IL-1) possesses a wide variety of biological activities and is produced by leukocytes as well as by various other cells including cells from endocrine tissues and might play a role as a paracrine factor in the control of PTH secretion. We investigated the effect in vitro of IL-1 beta on PTH release, PTHmRNA and the mRNA for the extracellular calcium-sensing receptor (CaR) levels in preparations of bovine parathyroid cells. PTH secretion from cultured parathyroid tissue slices was significantly inhibited in a medium containing IL-1 beta at a concentration of 2000 pg/ml (PTH in % of control: 63.5 +/- 5.3), n=10 (p<0.01). The inhibitory effect of IL-1 beta was not found in preparations of dispersed cells. The inhibitory effect of IL-1 beta could be counteracted by the IL-1 receptor antagonist (IL-1ra), indicating that the inhibitory effect was mediated through the specific IL-1 receptor on the parathyroid cells. IL-1 beta (2000 pg/ml) up-regulated CaRmRNA levels to 180% of control, whereas no change in PTHmRNA was found. IL-1ra abolished the upregulating effect of IL-1 beta on the CaRmRNA. This study demonstrates a direct effect in vitro of IL-1 beta on PTH secretion from bovine parathyroid glands, an effect which may be mediated at least in part through the specific IL-1 receptor causing an upregulation of the calcium-sensing receptor mRNA. IL-1 might therefore play a role as a auto- and/or paracrine factor in the regulation of the PTH secretion.

Body composition changes measured by dual-energy X-ray absorptiometry in patients receiving home parenteral nutrition

BACKGROUND

To monitor changes in body composition in patients receiving home parenteral nutrition (HPN) and to ascertain whether changes were related to the amount of energy supplied by HPN, we studied prospectively patients with gut failure maintained on HPN.

METHODS

Patients were subjected to repeated measurement of body composition by dual-energy X-ray absorptiometry (DXA), the second investigation being performed after a mean period of 20 (range, 11-26) months. Thirty-two patients were included, one patient was excluded, and five patients died during the study period. At inclusion, the patients had received HPN for a mean period of 30 (range, 6-216) months. The indication for HPN was inflammatory bowel disease (n = 16), abdominal cancers (n = 5), and scleroderma and others (n = 11). The fat-free mass (FFM), fat mass (FM), and total body mineral content (TBMC) were measured by DXA.

RESULTS

Mean body mass index decreased from 21.18 to 20.96 kg/m2 (P = 0.36). The mean FFM showed a small, insignificant increase to 37.68 kg (P = 0.71). Mean TBMC was unchanged at 2.28 kg, and mean FM decreased from 19.25 to 18.17 kg (P = 0.055). During the study period the mean daily energy supply by HPN was reduced from kcal 1195 to kcal 959 (P = 0.004). There was a direct positive correlation between the individual changes in HPN energy supply and body weight and FFM (r = 0.437, r = 0.410, P < 0.05).

CONCLUSION

The body composition of HPN patients was stable, with no change in mean FFM, FM, or TBMC. Individual changes in body weight and FFM correlated with change in HPN energy supply.

Loss of bone mineral of the hip assessed by DEXA following tibial shaft fractures

We measured prospectively early changes (0-6 months) in bone mineral of the hip, the lumbar spine, and the tibia following tibial shaft fractures (n = 12), and in a cross-sectional study we evaluated the maximal amount of bone loss possible at the hip and tibia following long-term (average 3 years) impaired limb function as a consequence of complicated tibial shaft fractures [delayed union or nonunion (n = 7), chronic osteomyelitis (n = 5), decreased limb length (n = 1), or bone defect (n = 1)]. Bone mineral measurements were performed by dual energy X-ray absorptiometry. Following tibial shaft fractures, a significant decrease in bone mineral density (BMD) was seen at the hip reaching 7% [confidence limits (CL): -10.2%; -3.5%] and 14% (CL: -19.6; -7.8%) after 6 months for the femoral neck and greater trochanter, respectively. In the proximal tibia, bone mineral content (BMC) decreased and was 19% (CL: -27.4%; -9.9%) below the initial value after 6 months. BMD of the lumbar spine remained unchanged. In the cross-sectional study, BMC in the tibia of the injured legs was 43% (CL: -53.2%; -31.9%) below the value in the healthy contralateral legs, and BMD in the femoral neck and greater trochanter, respectively, was 22% (CL: -27.4%; -17.6%) and 24% (CL: -36.3%; -12.1%) below the values in the healthy contralateral legs. With respect to the expected age-related decay of bone mineral after peak bone mass, the loss of bone mineral of the hip and tibia associated with tibial shaft fractures may be considered of clinical importance with increased risk of sustaining a fragility fracture of the lower extremity later in life; and the complicated fractures may even represent a present risk of fracture.

Effect of vitamin D metabolites and analogs on renal and intestinal calbindin-D in the rat

The effects on renal and intestinal calbindin-D of vitamin D3 metabolites and synthetic 20-epi-vitamin D3 analogs with different calcemic actions were examined in Wistar rats. The compounds were administered intraperitoneally once daily for 5 days. The dosages of the metabolites were 1,25-(OH)2D3 0.01, 0.05, 0.1, and 0.4 microg/kg x d, 24,25-(OH)2D3 0.1, 1 and 10 microg/kg x d, and 25-(OH)D3 10 and 400 microg/kg x d. The dosage of the synthetic analogs were MC903 0. 1, 10, and 100 microg/kg x d, EB1213 0.1 and 10 microg/kg x d, KH1060 0.1 and 0.4 microg/kg x d, and GS1725 0.01 and 0.1 microg/kg x d. Two control groups had either vehicle alone or no treatment. N = 8 in each group. 1,25-(OH)2D3 increased renal and intestinal calbindin-D levels, induced hypercalcemia, and suppressed plasma PTH and magnesium concentrations. 24,25-(OH)2D3 increased intestinal calbindin-D9k and plasma calcium, but had no effect on renal calbindin-D28k, plasma PTH, and magnesium. The dosage of 24, 25-(OH)2D3 that was required to increase plasma calcium was larger than the dosage required to increase intestinal calbindin-D9k. 25-(OH)D3 did not change the calcium metabolic parameters. MC903, a low calcemic analog with a relative high affinity for the vitamin D receptor and a short half-life, increased renal calbindin-D28k without increasing ionized calcium or intestinal calbindin-D9k. EB1213, an analog with a reduced calcemic action and short half-life, increased renal calbindin-D28k and ionized calcium without increasing intestinal calbindin-D9k. The effect of the high calcemic vitamin D analogs KH1060 and GS1725 on calbindin-D was directly related to their calcemic activity. In conclusion, these results demonstrate that 24,25-(OH)2D3 increases intestinal calbindin-D9k, but has no effect on renal calbindin-D28k, that low calcemic analogs may increase renal calbindin-D28k without increasing intestinal calbindin-D9k, and that the effect of high calcemic analogs on calbindin-D is directly related to their calcemic activity.

The relation between trabecular bone strength and bone mineral density assessed by dual photon and dual energy X-ray absorptiometry in the proximal tibia

The feasibility of two noninvasive methods [dual photon absorptiometry (DPA) and dual energy X-ray absorptiometry (DXA)] for prediction in vivo of local variations of trabecular bone strength within the proximal tibia was evaluated in 14 cadaveric knees. Trabecular bone strength was measured using an osteopenetrometer and from destructive compression tests performed on bone cylinders, thus measuring the penetration strength and ultimate strength in the medial, lateral, and central part of the tibial bone specimens. Linear regression analysis showed significant relations between BMD measured by DPA (r2 = 72%) or DXA (r2 = 73%) and ultimate strength. Even closer relations between BMD (DPA: r2 = 80%, DXA r2 = 81%) and penetration strength of trabecular bone were found. We conclude that DPA and DXA are suitable methods for evaluation in vivo of local variations in trabecular bone strength within the proximal tibia, and could easily be performed preoperatively before insertion of total knee arthroplasty.

Ectopic production of intact parathyroid hormone by a squamous cell lung carcinoma in vivo and in vitro

Ectopic tumoral production of intact parathyroid hormone (PTH) is rare. The PTH-related protein is the common cause of hypercalcemia in most solid tumors, particularly squamous and renal carcinomas. We report the case of a 71-yr-old man with a PTH-producing squamous cell lung carcinoma. Immunocytochemical analysis of the tumor tissue as well as of cultured tumor cells revealed PTH positive staining. Cultured tumor cells released PTH and were calcium sensitive, producing 122 +/- 16 pg/microgram DNA of intact PTH (mean +/- SEM) at 0.5 mmol/L calcium compared with 26 +/- 2 pg/microgram DNA at 3.0 mmol/L calcium. Somatostatin analogues have been used in the treatment of humoral hypercalcemia of malignancy (HHM). However, we found that somatostatin (0.1 microgram/L) in cultured tumor cells increased the release of intact PTH (123 +/- 19 versus 82 +/- 1 pg/microgram DNA, P < 0.05) and thus might have a negative effect on the HHM. This report is the first to describe a true ectopic PTH-producing squamous cell lung carcinoma associated with HHM.

A direct effect in vitro of phosphate on PTH release from bovine parathyroid tissue slices but not from dispersed parathyroid cells

BACKGROUND

Phosphate retention has long been considered to be of importance for the pathogenesis of secondary hyperparathyroidism in chronic renal failure. Hyperphosphatemia in vivo is associated with alterations of calcium and vitamin D levels, both of which are known to alter the parathyroid hormone (PTH) release independently.

MATERIALS AND METHODS

We have investigated the direct effect of phosphate on PTH release in vitro using two different preparations of bovine parathyroid tissue: Acutely dispersed bovine parathyroid cells and tissue slices of 0.5 x 0.5 mm were prepared from bovine parathyroid glands. Parathyroid dispersed cells and tissue slices were incubated for 4 h in media containing normal phosphate (1.0 mM) or high phosphate (3.5 mM).

RESULTS

High phosphate induced a significant (P < 0.01) increase in PTH release in the preparation of tissue slices, but not in preparations of dispersed cells. The 4 h incubation in high phosphate medium did not change the set-point for calcium. Bovine parathyroid tissue slices incubated in increasing phosphate concentrations from 1.0 to 3.5 mM and with a fixed calcium concentration of either 0.8, 1.2 or 1.8 mM responded with a dose dependent stimulation of PTH release. The degree of stimulation of release by high phosphate (3.5 mM), was significantly (P < 0.05) higher at low calcium levels (0.8 mM), 172% above baseline value (1.0 mM phosphate) as compared to high calcium levels (1.8 mM), 139% above baseline values.

CONCLUSIONS

This study shows that phosphate directly stimulates the PTH release in bovine parathyroid glands, and that this effect is only seen in preparations of parathyroid tissue slices and not in preparations of dispersed cells. This indicated that maintenance of near normal architecture of the parathyroid glands is essential in order to elicit the effect of high phosphate on the PTH release.

Effect of parathyroid hormone on renal calbindin-D28k

The present investigation was conducted to examine the effects of parathyroid hormone (PTH) and parathyroid hormone related peptide (PTHrP) on renal calbindin-D28k in rats. Four groups of studies were performed: (1) parathyroidectomy (PTX) or a sham operation followed by infusion of 1,25-dihydroxyvitamin D (1,25[OH]2D) or vehicle; (2) infusions of PTH(1-34), PTH(1-84), 1,25(OH)2D, or vehicle; (3) infusion of PTHrP(1-34), PTHrP (1-86), PTH(1-34), or vehicle; and (4) injections of calcium or vehicle. PTX reduced renal calbindin-D28k levels even when plasma concentrations of 1,25(OH)2D were kept constant by infusion of 1,25(OH)2D. Infusions of PTH(1-34), PTH(1-84), and 1,25(OH)2D all increased renal calbindin-D28k and plasma calcium, whereas PTHrP(1-34) and PTHrP(1-86) increased renal calbindin-D28k before an increase of plasma calcium took place. Hypercalcemia induced by the injection of calcium did not affect the levels of renal calbindin-D28k. The present data suggest that PTH and PTHrP exert a direct effect on renal calbindin-D28k, which is not mediated by changes of 1,25(OH)2D or calcium.

Body composition in patients on home parenteral nutrition

Dual energy X-ray absorptiometry (DXA) measures and separates three of the principal compartments of the body, fat mass (FM), fat-free mass (FFM), comprising muscle, inner organs and body water, and the total bone mineral content (TBMC). The aim of the present study was to determine body composition by DXA scan in 37 patients who had been on home parenteral nutrition (HPN) for 6-216 months. The height and weight of patients were significantly lower when compared to a group of healthy subjects. The weight, however, was relatively more reduced than the height. This is reflected by a significantly reduced body mass index in young female and male patients (p < 0.05). Fat-free mass and total body mineral content were significantly reduced (p < 0.05) in patients on home parenteral nutrition compared to a group of healthy subjects. However, the percentage of fat-free mass was unchanged. No significant change in fat mass was observed. We conclude that patients, with intestinal failure due to short bowel syndrome, who are on HPN have a smaller body size with a normal relative body composition.

Long-term effects of intravenous 1 alpha (OH)D3 combined with CaCO3 and low-calcium dialysis on secondary hyperparathyroidism and biochemical bone markers in patients on chronic hemodialysis

The effects of intravenous administration of 1 alpha-hydroxycholecalciferol [1 alpha (OH)D3] in combination with CaCO3 and 'low-calcium dialysis' (1.25 mmol/l) on plasma (p) parathyroid hormone (PTH) and biochemical bone markers (osteocalcin, alkaline phosphatase, procollagen type 1 c-terminal extension peptide) were examined in 54 patients on chronic hemodialysis with either normal or elevated PTH. Increasing doses of 1 alpha (OH)D3 were administered intravenously under careful control of p-Ca2+ and inorganic phosphate. Blood samples were obtained 1 week before the start of treatment and then every 2nd week. 20 patients with initially normal PTH levels (23.5 +/- 4.17 pg/ml) and 34 patients with initially elevated PTH levels (301 +/- 45 pg/ml) were followed for up to 88 weeks. The present investigation: demonstrated: (1) 'Low-calcium hemodialysis' (1.25 mmol/l) made it possible to use larger doses of CaCO3 and to reduce the doses of an aluminium-containing oral phosphate binder. A decrease in p-Ca2+ during dialysis was induced, and special care had to focus on the compliance to CaCO3, in order not to aggravate the secondary hyperparathyroidism. (2) The combination of 'low-calcium hemodialysis', CaCO3, and pulse intravenous 1 alpha (OH)D3 prevented the development of secondary hyperparathyroidism in patients with normal PTH levels and induced a long-term suppression of p-PTH (106 +/- 25 pg/ml, 88 weeks) in the patients with secondary hyperparathyroidism. By careful monitoring, severe hypercalcemia and hyperphosphatemia were avoided. There were no indications, clinically or biochemically, of development of adynamic bone disease. (3) Bone lesions were healed and a decrease of the bone mineral content in lumbar spine and femoral neck of patients with both normal and elevated PTH levels prevented. (4) The present results may suggest that PTH might be of influence on that regulation of procollagen type 1 c-terminal extension peptide.

Purification and characterization of porcine pepsinogen B and pepsin B

Porcine pepsinogen B was prepared from extracts of adult porcine fundic mucosa. Immunoelectrophoresis showed no immunochemical cross-reactions between pepsinogen B and other porcine gastric zymogens. Pepsin B was purified after activation of the zymogen. The enzyme showed an optimum of general proteolytic activity at pH 3.0. Activation of pepsinogen B at pH 2 resulted in formation of the covalent intermediate (pseudo-pepsin B) by proteolytic cleavage of bond Met16p-Glu17p (pig pepsinogen A numbering, "p" indicates residues of the prosegment peptide). Pseudopepsin B was stable at pH 2. The intermediate was converted to pepsin B at pH 5.5. The overall activation of pepsinogen B was much slower than found for other investigated gastric zymogens. During the conversion of pepsinogen B to mature pepsin B a segment of 43 amino acid residues was cleaved from the N-terminal of pepsinogen B. The amino acid sequence of the prosegment and the first 24 residues of pepsin B was determined. Relative to porcine pepsinogen A, progastricsin, and prochymosin, the following degrees of identities were observed: 40, 55, and 51%.

The calcium/parathyroid hormone concept of the parathyroid glands

Plasma ionized calcium is the major determinant of parathyroid hormone (PTH) secretion. The minute-to-minute secretory response of the parathyroids to changes in plasma ionized calcium is described by the calcium/PTH concept, but the detailed mechanism is not yet well understood. The recent cloning of a calcium-sensing receptor in the plasma membrane of the parathyroid cells will probably yield important information concerning the mechanisms by which calcium and other ions control the parathyroid function. It is likely that autocrine and paracrine factors also participate in the regulation of PTH secretion. PTH, chromogranin A, chromogranin A-related peptides and endothelin-1 have been suggested as autocrine factors. More documentation is needed on the impact of these factors in the physiology of the parathyroid gland. In-vivo investigations of the parathyroid function are difficult to interpret because of the complexity of the PTH secretory response to hypo- and hypercalcaemia. Rate dependency and the ability of the parathyroids to sense the direction of changes in calcium make the existing models for investigating the calcium/PTH relationship inappropriate. In vitro, the models are compromised by a rapid drop in the expression of the calcium-sensing receptor of the cultured parathyroid cells. We, therefore, recommend caution when using the calcium/PTH concept in clinical or experimental investigations.

Ketamine in the treatment of bronchospasm during mechanical ventilation

The effect of ketamine on bronchospasm during mechanical ventilation was evaluated in a prospective, placebo-controlled, double-blind trial. Fourteen mechanically ventilated patients with bronchospasm were randomly allocated to either ketamine 1 mg/kg or saline placebo. In the ketamine-treated patients, PO2 increased from 10.5 (+/- 0.5) kPa to 16.4 (+/- 2.7) kPa (P < .05), whereas PO2 in the placebo-treated patients remained unchanged. The PCO2 was constant in the ketamine group, although it increased from 5.6 (+/- 0.9) kPa to 6.1 (+/- 0.9) kPa in the placebo group (P < .05). The pulmonary stethoscopic bronchospasm improved immediately after the administration of ketamine, whereas the thoracic compliance remained unchanged. In conclusion, the ketamine-treated patients showed an improvement by stethoscopic examination, in PO2 and in PCO2, suggesting that ketamine might be useful in the treatment of bronchospasm during mechanical ventilation. However, further studies are required to decide whether ketamine should be considered the drug of choice in patients with severe bronchospasm during ventilator treatment.

[PermCath as intravenous access in chronic hemodialysis]

PermCath is a dual-lumen silicone catheter for permanent venous access for hemodialysis. During an observation period from 1 July 1988 to 30 June 1991, 49 PermCath were inserted in 32 patients. In 24 patients (75%), the PermCath was used as sole method of access for hemodialysis through the observation period. Six of the 24 patients required changing of the catheter once, and in three patients the PermCath functioned properly only after the third insertion of a PermCath. In eight patients, vascular access could not be accomplished using the PermCath and these patients were all hemodialyzed through another vascular access. Four patients developed bacteraemia and one patient developed thrombosis of the subclavian vein during the observation period. Insertion of the PermCath is easy and, in case of malfunction, changing or removal of the catheter is easily accomplished. The PermCath is recommended as an alternative to existing techniques for intravenous access for hemodialysis.

Separation of porcine pepsinogen A and progastricsin. Sequencing of the first 73 amino acid residues in progastricsin

Porcine pepsinogen A (EC 3.4.23.1) and progastricsin (EC 3.4.23.3) have been separated by chromatography on DEAE-cellulose followed by chromatography on DEAE-Sepharose. Agar gel electrophoresis at pH 6.0 showed the presence of three components of pepsinogen A and two of progastricsin. During activation at pH 2 a segment of 43 amino acid residues (the prosegment peptide) is cleaved from the N-terminus of progastricsin. The sequence of this was determined; in addition, the first 30 residues of gastricsin were sequenced. The sequence of the first 73 amino acid residues of progastricsin shows an overall identity with progastricsins from man, monkey and rat of 67%. The overall identity with other zymogens for gastric proteinases is 27%. The highly conserved Lys36p (pig pepsinogen A numbering) is changed to Arg in porcine progastricsin.

Long-term suppression of secondary hyperparathyroidism by intravenous 1 alpha-hydroxyvitamin D3 in patients on chronic hemodialysis

The effect of intravenous 1 alpha-hydroxyvitamin D3 [1 alpha(OH)D3] on circulating levels of intact parathyroid hormone (PTH 1-84) and COOH-terminal immunoreactive PTH(PTH 53-84) was examined in 13 patients on chronic hemodialysis. Thirteen patients were treated for 300 days (10 months), 9 patients for 520 days (14 months) and 6 patients for 720 days (2 years) with increasing doses of 1 alpha(OH)D3 intravenously under careful control of plasma Ca2+. Blood samples were obtained 1 week before start of treatment and then at every 2nd week. None of the patients had previously been treated with oral vitamin D metabolites. Intact PTH levels were maximally suppressed after 27-33 weeks of treatment by approximately 73%. At the end of the study periods, PTH 1-84 was still suppressed by 78 +/- 4.3% after 300 days, 78 +/- 8.8% after 520 days and 85 +/- 6.5% after 720 days. Plasma Ca2+ was kept within normal levels, but showed an initial increase from 1.14 +/- 0.03 to 1.27 +/- 0.15 mmol/l, and an adjustment of the doses of 1 alpha(OH)D3 was necessary. The present investigation demonstrated (1) that intravenous administration of the 1-hydroxylated vitamin D metabolite 1 alpha(OH)D3 induced a significant decrease in circulating levels of biologically active intact PTH, and (2) that it was possible to maintain the marked suppression of PTH secretion by intravenous treatment of 1 alpha (OH)D3 for up to 2 years. Hypercalcemia could be avoided by careful monitoring of plasma Ca2+ and adjustment of the doses of 1 alpha(OH)D3.

Hydrophobic Grid Membrane Filter Method for Aerobic Plate Count in Foods: Collaborative Study

Twenty-one laboratories participated in a collaborative study to validate a hydrophobic grid membrane filter (HGMF) method for aerobic plate count by comparing its performance against the AOAC/APHA pour plate method. Raw milk, raw poultry, whole egg powder, flours, and spices were included in the study. Counts obtained by the HGMF and pour plate methods did not differ significantly, except in the case of whole egg powder, for which the HGMF method produced significantly higher counts. The hydrophobic grid membrane filter method for aerobic plate count in foods has been adopted official first action.