Impaired osteoclastic bone resorption leads to osteopetrosis in cathepsin-K-deficient mice

Cathepsin K is a recently identified lysosomal cysteine proteinase. It is abundant in osteoclasts, where it is believed to play a vital role in the resorption and remodeling of bone. Pycnodysostosis is a rare inherited osteochondrodysplasia that is caused by mutations of the cathepsin-K gene, characterized by osteosclerosis, short stature, and acroosteolysis of the distal phalanges. With a view to delineating the role of cathepsin K in bone resorption, we generated mice with a targeted disruption of this proteinase. Cathepsin-K-deficient mice survive and are fertile, but display an osteopetrotic phenotype with excessive trabeculation of the bone-marrow space. Cathepsin-K-deficient osteoclasts manifested a modified ultrastructural appearance: their resorptive surface was poorly defined with a broad demineralized matrix fringe containing undigested fine collagen fibrils; their ruffled borders lacked crystal-like inclusions, and they were devoid of collagen-fibril-containing cytoplasmic vacuoles. Assaying the resorptive activity of cathepsin-K-deficient osteoclasts in vitro revealed this function to be severely impaired, which supports the contention that cathepsin K is of major importance in bone remodeling.     

Histological studies in the developing eyelids of congenital microphthalmic (Cts) mice

The Cts mouse is a mutant of the Jcl:ICR strain with congenital cataract and small eyes in homozygotes. In the present study, attempts were made to measure postnatally the palpebral fissure and to examine the process of eyelid development by light microscopy in both normal (+/+) and homozygous (Cts/Cts) mice. The width of the palpebral fissure in homozygotes was significantly smaller than in unaffected mice. To investigate the process of eyelid development, tissue specimens from normal and Cts homozygous mice were prepared with hematoxylin and eosin, and observed by light microscopy on days 14, 16, and 18 of gestation and on days 0, 7, and 14 after birth. In both groups, the eyelid fused on day 16 of gestation and opened completely on day 14 after birth. The primordium of the orbicularis oculi muscle was defined on day 16 of gestation, and the primordia of hair follicles and Meibomian glands were detected on day 18 of gestation. In the present study, there were no significant differences in the process of eyelid development between normal and homozygous mice. Eyelid development has thus far been thought to be self-determining and not affected by tissue interaction, and the present findings support this line of thought.     

Transplantation of cord blood progenitor cells can promote bone resorption in autosomal recessive osteopetrosis

Allogeneic BMT has been reported to be the only curative therapy for children with juvenile autosomal recessive osteopetrosis. We report the case of a 14-month-old child in whom bone resorption was observed after cord blood transplantation (CBT). The patient was given CBT from an unrelated newborn matched for five of six HLA antigens. At the time of transplantation, the child presented with neurological symptoms, with feeding problems and visual impairment. A successful engraftment of donor hematopoiesis was demonstrated and the child experienced grade I acute GVHD. Progressive bone clearing was achieved and a bone marrow trephine demonstrated signs of osteoclast function. Despite full engraftment and bone resorption, neurologic deterioration did not improve. This experience documents that CBT can promote the correction of juvenile osteopetrosis. The shorter time needed both to identify an unrelated donor and to perform the transplant, as well as the lower incidence of GVHD make this procedure more appealing than BMT in children lacking an HLA-compatible relative.     

Selective impairment of response to acetylcholine after ischemia/reperfusion in mice

BACKGROUND AND PURPOSE: We previously reported that the endothelium-dependent dilation of pial arterioles by either topical acetylcholine (ACh) or bradykinin (BK) was markedly inhibited after 10 minutes of near total ischemia after bilateral carotid occlusion. The present study tests the responses after 10 minutes of reperfusion and investigates the effect of either oxygen or oxygen radical scavengers on the results. METHODS: Mice were subjected to bilateral carotid ligation or sham ligation. Pial arteriolar diameters were monitored by an image-splitting technique at a craniotomy site. In separate studies, the responses to topically suffused ACh, BK, or sodium nitroprusside (SNP) were tested before ischemia. After 10 minutes of ischemia and 10 minutes of reperfusion, the response was assessed again. Sham-operated mice were observed in each study. Cerebral blood flow was continuously monitored with a laser-Doppler technique. Additional separate studies were conducted as follows: presence of superoxide dismutase plus catalase during ischemia and reperfusion, or increase in the inspired oxygen (arterial oxygen) and oxygen in suffusate. RESULTS: The response to ACh was significantly impaired after 10 minutes of reperfusion. The responses to BK and SNP were unaffected. Radical scavengers failed to influence the impaired response to ACh. Elevations of arterial and suffusate oxygen levels to over 300 mm Hg failed to prevent the impairment. CONCLUSIONS: After 10 minutes of reperfusion, a selective impairment of the response to ACh remains. The response to another endothelium-dependent dilator, BK, recovered, and the response to endothelium-independent SNP was unaffected. Because neither radical scavengers nor oxygen altered the outcome with respect to ACh, I suggest that neither radical generation nor hypoxia accounts for the selective impairment of dilation by ACh. Rather, I hypothesize that reduced shear during ischemia diminishes the ability of the endothelium to synthesize and/or release the endothelium-derived relaxing factor for ACh. I hypothesize further that this impaired release or synthesis persists throughout the 10-minute period of reperfusion.     

Histomorphometric evidence for echistatin inhibition of bone resorption in mice with secondary hyperparathyroidism

Echistatin, an RGD-containing peptide, was shown to inhibit the acute calcemic response to exogenous PTH or PTH-related protein (PTH-rP) in thyroparathyroidectomized rats, suggesting that echistatin inhibits bone resorption. In this study: 1) we present histological evidence for echistatin inhibition of bone resorption in mice with secondary hyperparathyroidism, and show that 2) echistatin binds to osteoclasts in vivo, 3) increases osteoclast number, and 4) does not detectably alter osteoclast morphology. Infusion of echistatin (30 microg/kg x min) for 3 days prevented the 2.6-fold increase in tibial cancellous bone turnover and the 36% loss in bone volume, produced by a low calcium diet. At the light microscopy level, echistatin immunolocalized to osteoclasts and megakaryocytes. Echistatin treatment increased osteoclast-covered bone surface by about 50%. At the ultrastructural level, these osteoclasts appeared normal, and the fraction of cells containing ruffled borders and clear zones was similar to controls. Echistatin was found on the basolateral membrane and in intracellular vesicles of actively resorbing osteoclasts. Weak labeling was found in the ruffled border, and no immunoreactivity was detected at the clear zone/bone surface interface. These findings provide histological evidence for echistatin binding to osteoclasts and for inhibition of bone resorption in vivo, through reduced osteoclast efficacy, without apparent changes in osteoclast morphology.     

Biochemical analysis of the response in rat bone marrow cell cultures to mechanical stimulation

Bone marrow cells obtained from rat femora were subjected to primary culture with 15% fetal bovine serum in the presence of 10(-8) M dexamethasone, and following trypsin treatment 5 days later were seeded on Petriperm dishes which have a flexible bottom. After a 2-day subculture, a cyclic stress consisting of a 1 s stretch (0.3% strain. 0.5 Hz) and a 1 s relaxation for 30 min every day was started. Culture tissue was removed on day 2 of the subculture (immediately prior to start of stimulation), and then on days 5 and 8 (3 and 6 days after the start of stimulation, respectively), at which times dry weight, DNA, alkaline phosphatase (ALP) activity, and bone Gla protein (BGP, osteocalcin) were measured. Both the dry weight and DNA showed a significant increase in the stimulated group by day 8, while the ALP activity showed a significant increase by day 5. The BGP began to increase in the stimulated group on day 5 in contrast to the control group in which it only increased on day 8. These results support the contention that mechanical stimulation promotes the differentiation of osteogenic cells and enhances bone formation. Since in this experimental model the acceleration of bone formation by mechanical stimulation can be reproduced in vitro, it is extremely useful for investigating the mechanisms underlying mechanical stimulation.     

Effects of calcium supplementation using AAACa or milk on nocturnal bone resorption in young women

In order to study the effect of calcium supplementation on bone resorption, a randomized controlled crossover study was carried out on eight healthy 18-19 year old female volunteers using either AAACa heated oyster shell with vacuum-heated seaweed or milk. Regimen A consisted of an oral dose of 200 mg calcium in the form of AAACa. B 200 ml milk after breakfast and supper and at bedtime, and C control with no calcium supplement. Early morning fasting blood and urine sampling was carried out after 7 days of calcium supplementation. Serum calcium was higher in groups A and B than in C, and serum intact parathyroid hormone (PTH) was significantly lower in group A than in groups B and C, according to a paired t-test. Urinary excretion of crosslinked collagen degradation product, pyridinoline and deoxypyridinoline showed a similar decrease in groups A and B but not in C. The more effective suppression of PTH by AAACa than by milk may be due to its higher bioavailability and the absence of phosphate stimulating PTH secretion.     

Evaluation of bone turnover in type I osteoporosis using biochemical markers specific for both bone formation and bone resorption

Multivariate analysis was used to determine which characteristics: sex of the proband, sibling sex, severity of the proband's defect or family history, are the best predictors of recurrence risk among siblings of individuals with non-syndromic cleft lip with or without cleft palate (CL +/- P). Sibling recurrence risks are not significantly related to the sex of the proband. Severity of the proband's defect, classified by the extent of the lip defect (unilateral versus bilateral), was found to be a significant predictor of sibling recurrence, whereas involvement of the palate in the proband's defect was not. A positive family history of clefting (i.e. at least one affected first-degree relative in addition to the proband) and the sex of the sibling were also found to be significant predictors of sibling recurrence. The associations between sibling risk and family history, and sibling risk and bilaterality of the proband's defect appear to be mildly confounded. After adjusting for the effects of family history, the risk to siblings of probands with bilateral lip defects is twice the risk to siblings of probands with unilateral defects (O.R. = 2.00; 95% C.I. 1.25-3.19). A positive family history of clefting increases the risk to siblings by greater than 4-fold (O.R. = 4.49; 95% C.I. 2.74-7.35), after adjusting for the extent of the proband's lip defect. These results provide a rational strategy for identifying subsets of the 'at risk' population which have markedly different recurrence risks. This information is important for genetic counseling, since it allows for more precise estimation of sibling recurrence risks in individual cases.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impact of habitual cocaine smoking on the physiologic response to maximum exercise

BACKGROUND: Habitual smoking of alkaloidal cocaine (crack) has been reported to be associated with a number of cardiopulmonary complications that may not be clinically obvious but could potentially interfere with normal physiologic responses to exercise and thus impair maximum exercise performance. STUDY OBJECTIVE: To evaluate the impact of regular use of cocaine on maximum exercise. DESIGN: Observational study in crack users and age- and gender-matched control subjects. SUBJECTS: Thirty-five habitual cocaine smokers (21 male and 14 female) and 29 age-matched sedentary control nonsmokers of cocaine (15 male and 14 female), all of whom were in good general health. METHODS: In these subjects, we compared physiologic responses to symptom-limited, incremental maximal exercise performed on a cycle ergometer using a ramp protocol. Comparisons were made for men and women separately. RESULTS: For both men and women, long-term cocaine smokers had a reduced aerobic capacity (maximum oxygen consumption) compared with control nonsmokers but did not show evidence of ventilatory limitation, reduced gas exchange threshold, increased physiologic dead space, or gas exchange abnormality at maximum exercise compared with the healthy control subjects. Although cocaine smokers had reduced maximum heart rates compared with control subjects, the relationship between submaximal heart rate and oxygen uptake was normal, indicating a normal cardiovascular response pattern. However, effort perception was similar between the two groups despite the difference in heart rate at maximum exercise, suggesting the possibility of perceptual dysfunction for effort. Differences in aerobic capacity between the crack users and nonusers could not be explained by differences in physical fitness or altered perception of dyspnea. CONCLUSION: In the subjects we studied, long-term cocaine smoking was associated with reduced maximum exercise performance, probably due to poor motivation or altered effort perception. No other identifiable physiologic abnormality appeared to limit exercise in the habitual crack users.     

Studies on novel bone resorption inhibitors. II. Synthesis and pharmacological activities of fused aza-heteroarylbisphosphonate derivatives

Two new series of fused aza-heteroarylbisphosphonates (5, 8), which are structurally quite different from incadronate (YM175), and related compounds were synthesized and evaluated for antiresorptive activity using a parathyroid hormone(PTH)-induced hypercalcemia model in rats (PIH model). Among these compounds, several exhibited more potent antiresorptive activity than pamidronate. In particular, [1-hydroxy-2-(imidazo[1,2-a]pyridin-3-yl)ethylidene]bisphosphonic acid (5b, minodronate) was 100-fold more potent than pamidronate in not only the PIH model, but also in an immobilization bone atrophy model in rats (DA model), and was selected for clinical development. The structure-activity relationships in these new series of bisphosphonates are discussed.     

The cellular actions of interleukin-11 on bone resorption in vitro

The pleiotropic cytokine interleukin-11 (IL-11) stimulates osteoclast formation in vitro, but it is not known whether it influences other steps in the bone-resorptive cascade. Using a variety of in vitro model systems for studying bone resorption we have investigated the effects of IL-11 on 1) osteoclast formation, fusion, migration, and activity; and 2) osteoblast-mediated osteoid degradation. The involvement of matrix metalloproteinases (MMPs) and products of arachidonic acid metabolism in IL-11-mediated resorption were also assessed. We first examined the bone-resorptive effects of IL-11 by assessing 45Ca release from neonatal mouse calvarial bones. IL-11 dose-dependently stimulated bone resorption with an EC50 of 10(-10) M. The kinetics of IL-11-mediated 45Ca release demonstrated that it was without effect for the first 48 h of culture, but by 96 h, it stimulated 45Ca release to the same level as that produced by 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] (a hormone that stimulates osteoclast formation and activity). IL-11 also produced a dose-dependent increase in osteoblast-mediated type I collagen degradation with a maximum of 58.0 +/- 6.2% at 5 x 10(-9) M; this effect of IL-11 was less than that produced by 1,25-(OH)2D3 (76.5 +/- 7.1%) and was prevented by an inhibitor of MMPs, but not those blocking arachidonic acid metabolism. We then tested the effects of IL-11 on isolated mouse osteoclasts cultured on ivory slices in the presence and absence of primary mouse osteoblasts. IL-11 had no effect on isolated osteoclast activity even in coculture with primary osteoblasts. We then examined the effects of IL-11 on the formation of osteoclast-like multinucleate cells in mouse bone marrow cultures and the resorptive activity of such cultures using ivory as a substrate. IL-11 dose-dependently increased 1) the number of tartrate-resistant acid phosphatase-positive osteoclast-like multinucleate cells and 2) the surface area of lacunar resorption, although the effects were less than that of 1,25-(OH)2D3. The effect of IL-11 on bone marrow lacunar resorption was prevented by a combination of inhibitors of 5-lipoxygenase and cyclooxygenase. In 17-day-old metatarsal bones, IL-11 prevented the migration of (pre)osteoclasts to future resorption sites, whereas their fusion was unaffected. These results provide strong evidence that IL-11 stimulates bone resorption by enhancing osteoclast formation and osteoblast-mediated osteoid degradation rather than stimulating osteoclast migration and activity. Our data also suggest that the stimulatory effects of IL-11 involve both MMPs and products of arachidonic acid metabolism.     

Airway muscle in infants with congenital diaphragmatic hernia: response to treatment

BACKGROUND/PURPOSE: Airway muscle hyperactivity and chronic lung disease frequently follow congenital diaphragmatic hernia (CDH) treatment. The aim of this study was to compare the quantity of airway muscle and alveolar ductal artery muscle in CDH infants after various treatments. METHODS: Five groups were studied postmortem: CDH, died within 24 hours, without high ventilatory assistance (n = 3); CDH, various extracorporeal membrane oxgenation (ECMO) durations, without high ventilatory assistance (n = 4); CDH, various ECMO durations, with high ventilatory assistance (n = 7); no CDH, without high ventilatory assistance (n = 12); and no CDH, with high ventilatory assistance and bronchopulmonary dysplasia (BPD) (n = 5). Sections from standardized fixed lungs were immunohistochemically stained for alpha-smooth muscle actin. Muscle surrounding conducting airways from small preterminal bronchioles to bronchi was quantitated in both the ipsilateral and contralateral lungs with computerized image analysis. Similarly, muscle mass was quantitated in alveolar ductal arteries. RESULTS: CDH infants with low ventilatory assistance, regardless of postnatal age, had the same quantity of airway muscle as low ventilatory assistance controls. Infants with CDH and prolonged high ventilatory assistance had significantly more muscle throughout the conducting airways, similar to BPD infants without CDH, even though the CDH infants had significantly less exposure to high ventilatory assistance. With both low and high ventilatory assistance, the quantity of muscle in both the ipsilateral and contralateral lungs was similar. In contrast, small acinar arteries in CDH infants have increased muscle mass at birth. This muscle is decreased by ECMO but persists in CDH infants with high ventilatory assistance. CONCLUSIONS: The authors show that postnatally, CDH infants acquire increased muscle quantity throughout the conducting airways, in both the ipsilateral and contralateral lungs, with relatively short exposure to high ventilatory assistance. The normal decrease in acinar arterial mass that occurs postnatally is delayed in CDH infants with high ventilatory assistance.     

Burn healing in organ cultures of embryonic chicken skin: a model system

Burn wounds cause complex damage to the skin. Unlike simple cuts, burns cause a graded damage at the margin of the wound and leave biochemically complex debris in the wound, two factors that complicate the process of wound healing. To develop an in vitro system for studying cellular responses to burns in whole tissue, we have applied a standardized burn wound to organ cultures of embryonic chicken skin and evaluated cellular changes in response to the burn damage. This simplified system is not subject to uncontrolled infection and does not involve angiogenesis and granulation. Thus, these cultures provide a simplified model of how cells of the dermis and epidermis in and around a burn wound respond to heat damage early in the process of healing.     

Changes of bone metabolic markers in patients with bone metastases: clinical significance in assessing bone response to chemotherapy

To determine the changes in bone metabolism in response to combined chemotherapy in patients with bone metastases (BM), we examined osteocalcin (BGP), alkaline-phosphatase (ALP), hydroxyproline (HYP), pyridinoline (PYR), and/or deoxypyridinoline (D-PYR) in 25 cancer patients. In patients without BM, serum BGP was normal and not affected by chemotherapy. In patients with BM, however, BGP was often abnormally high or low, and some patients reacted to chemotherapy with a BGP increase at 4 weeks after initiation of therapy. Such an increase was observed in the group of patients who responded favorably to therapy as judged by a decrease in bone pain and tumor-associated biochemical markers. Urine HYP, PYR, and D-PYR were high in patients with BM before therapy; D-PYR decreased transiently at 2 weeks and increased thereafter. We assume that increased bone-resorption markers along with increased bone formation markers after therapy would indicate recovery of coupled bone metabolism, as the deranged bone remodeling is improved by tumor-regression. This study suggests that BGP and D-PYR can be useful early markers to predict favorable bone response to chemotherapy in patients with BM.     

Investigation of hearing impairment in Cavalier King Charles spaniels using auditory brainstem response audiometry

BACKGROUND: Gastrin has been shown to give an immediate and dose-dependent histamine release preceding acid secretion in the totally isolated, vascularly perfused rat stomach. METHODS: In the present study we prepared isolated, vascularly perfused stomachs taken from pigs and examined the effect of pentagastrin in a concentration of 520 pM on the histamine release to the vascular bed. Pentagastrin was given for three 5-min periods at 10-min intervals, and histamine was determined by a radioimmunoassay method. RESULTS: Each pentagastrin dose resulted in stimulation of histamine release in the three pig stomachs examined. The various histamine concentrations increased to levels previously shown to stimulate aminopyrine accumulation in isolated pig parietal cells. CONCLUSION: The present study shows for the first time that gastrin induces histamine release to the vascular bed in the pig, as previously shown for the rat and dog.     

Plasma leptin values in relation to bone mass and density and to dynamic biochemical markers of bone resorption and formation in postmenopausal women

A case of measles in a 26-year-old Japanese man is reported. A skin specimen taken on the third eruptive day from a maculopapular eruption on his chest was immunohistopathologically and electron microscopically examined using a rabbit polyclonal antibody against the nucleocapsid protein of the measles virus. The measles virus antigen was found in the inner cells of the acrosyringium and hair follicles. The measles virus nucleocapsid was electron microscopically identified in the nuclei of the inner cells of the acrosyringium. The findings suggest that the sweat from skin lesions might contain the measles virus.     

Prenatal diagnosis of congenital toxoplasmosis: comparative value of fetal blood and amniotic fluid using serological techniques and cultures

The management of patients with acute, severe ulcerative colitis requires careful in-hospital assessment of the patient and the coordinated treatment of a team of experienced gastroenterologists and surgeons. Complete understanding of the potential complications and their management, especially toxic megacolon, is essential. We review the current medical arsenal and advocate a standardized approach to management that includes continuous, high dose intravenous hydrocortisone, more aggressive use of topical steroids as well as feeding the patients and continuing (but not initiating) oral 5-aminosalicylic acid (5-ASA) agents. For those patients whose disease proves refractory to intravenous steroids, intravenous cyclosporin (with an acute response rate of 82%) is an essential component in the medical management of these patients. Antibiotics should be used only when specifically indicated. Total parenteral nutrition has not been shown to be helpful in the acute setting. Air contrast barium enema and colonoscopy have been used to predict response but may be dangerous diagnostic modalities in these acutely ill patients and are no better than good clinical judgement. We review and advocate long-term management of acute response using 6-mercaptopurine or azathioprine. The surgical experience and the postoperative complications of the ileal pouch anal anastomosis, which include acute pouchitis in 50-60%, chronic pouchitis in 5-10% and recent reports of dysplasia among patients with chronic pouchitis, must be considered before colectomy is advised. Over 80% of patients with acute severe colitis can be spared colectomy using our current arsenal of medical therapies.     

Markers of bone resorption predict hip fracture in elderly women: the EPIDOS Prospective Study

Increased bone turnover has been suggested as a potential risk factor for osteoporotic fractures. We investigated this hypothesis in a prospective cohort study performed on 7598 healthy women more than 75 years of age. One hundred and twenty-six women (mean years 82.5) who sustained a hip fracture during a mean 22-month follow-up were age-matched with three controls who did not fracture. Baseline samples were collected prior to fracture for the measurement of two markers of bone formation and three urinary markers of bone resorption: type I collagen cross-linked N- (NTX) or C-telopeptide (CTX) and free deoxypyridinoline (free D-Pyr). Elderly women had increased bone formation and resorption compared with healthy premenopausal women. Urinary excretion of CTX and free D-Pyr, but not other markers, was higher in patients with hip fracture than in age-matched controls (p = 0.02 and 0.005, respectively). CTX and free D-Pyr excretion above the upper limit of the premenopausal range was associated with an increased hip fracture risk with an odds ratio (95% confidence interval) of 2.2 (1.3-3.6) and 1.9 (1.1-3.2), respectively, while markers of formation were not. Increased bone resorption predicted hip fracture independently of bone mass, i.e., after adjustment for femoral neck bone mineral density (BMD) and independently of mobility status assessed by the gait speed. Women with both a femoral BMD value of 2.5 SD or more below the mean of young adults and either high CTX or high free D-Pyr levels were at greater risk of hip fracture, with an odds ratio of 4.8 and 4.1, respectively, than those with only low BMD or high bone resorption. Elderly women are characterized by increased bone turnover, and some markers of bone resorption predict the subsequent risk of hip fracture independently of hip BMD. Combining the measurement of BMD and bone resorption may be useful to improve the assessment of the risk of hip fracture in elderly women.