Functional ultrasound imaging of the spreading activity following optogenetic stimulation of the rat visual cortex.

Optogenetics has revolutionized neurosciences by allowing fine control of neuronal activity. An important aspect for this control is assessing the activation and/or adjusting the stimulation, which requires imaging the entire volume of optogenetically-induced neuronal activity. An ideal technique for this aim is fUS imaging, which allows one to generate brain-wide activation maps with submesoscopic spatial resolution. However, optical stimulation of the brain with blue light might lead to non-specific activations at high irradiances. fUS imaging of optogenetic activations can be obtained at these wavelengths using lower light power (< 2mW) but it limits the depth of directly activatable neurons from the cortical surface. Our main goal was to report that we can detect specific optogenetic activations in V1 even in deep layers following stimulation at the cortical surface. Here, we show the possibility to detect deep optogenetic activations in anesthetized rats expressing the red-shifted opsin ChrimsonR in V1 using fUS imaging. We demonstrate the optogenetic specificity of these activations and their neuronal origin with electrophysiological recordings. Finally, we show that the optogenetic response initiated in V1 spreads to downstream (LGN) and upstream (V2) visual areas.

Negative regulation of chemokine receptor CXCR4 by tumor suppressor p53 in breast cancer cells: implications of p53 mutation or isoform expression on breast cancer cell invasion.

Chemokine receptor CXCR4 and its ligand CXCL12 are suggested to be involved in migration, invasion and metastasis of breast cancer cells. Mutation of the tumor suppressor gene p53 in breast cancer is associated with metastasis and aggressive clinical phenotype. In this report, we demonstrate that wild type but not the dominant-negative mutant (V143A) or cancer-specific mutants (R175H or R280K) of p53 repress CXCR4 expression. Recently described cancer-specific p53 isoform, Delta133p53, also failed to repress CXCR4 promoter activity. Short-interfering RNA-mediated depletion of p53 increased endogenous CXCR4 expression in MCF-7 breast cancer cells that contain wild-type p53. Basal CXCR4 promoter activity in HCT116 colon carcinoma cells deleted of p53 [HCT116(p53KO)] was 10-fold higher compared to that in parental HCT116 cells with functional wild-type p53. Deletion analysis of CXCR4 promoter identified a seven-base pair p53-repressor element homologous to cyclic AMP/AP-1 response (CRE/AP-1) element. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed binding of ATF-1 and cJun to the CRE/AP-1 element. The p53 rescue drug PRIMA-1 reduced CXCR4 mRNA and cell surface expression in MDA-MB-231 cells, which express R280K mutant p53. CP-31398, another p53 rescue drug, similarly reduced cell surface levels of CXCR4. PRIMA-1-mediated decrease in CXCR4 expression correlated with reduced invasion of MDA-MB-231 cells through matrigel. These results suggest a mechanism for elevated CXCR4 expression and metastasis of breast cancers with p53 mutations or isoform expression. We propose that p53 rescue drugs either alone or in combination with chemotherapeutic drugs may be effective in reducing CXCR4-mediated metastasis.

Constitutive activation of NF-kappaB during progression of breast cancer to hormone-independent growth.

Breast cancers often progress from a hormone-dependent, nonmetastatic, antiestrogen-sensitive phenotype to a hormone-independent, antiestrogen- and chemotherapy-resistant phenotype with highly invasive and metastatic growth properties. This progression is usually accompanied by altered function of the estrogen receptor (ER) or outgrowth of ER-negative cancer cells. To understand the molecular mechanisms responsible for metastatic growth of ER-negative breast cancers, the activities of the transcription factor NF-kappaB (which modulates the expression of genes involved in cell proliferation, differentiation, apoptosis, and metastasis) were compared in ER-positive (MCF-7 and T47-D) and ER-negative (MDA-MB-231 and MDA-MB-435) human breast cancer cell lines. NF-kappaB, which is usually maintained in an inactive state by protein-protein interaction with inhibitor IkappaBs, was found to be constitutively active in ER-negative breast cancer cell lines. Constitutive DNA binding of NF-kappaB was also observed with extracts from ER-negative, poorly differentiated primary breast tumors. Progression of the rat mammary carcinoma cell line RM22-F5 from an ER-positive, nonmalignant phenotype (E phenotype) to an ER-negative, malignant phenotype (F phenotype) was also accompanied by constitutive activation of NF-kappaB. Analysis of individual subunits of NF-kappaB revealed that all ER-negative cell lines, including RM22-F5 cells of F phenotype, contain a unique 37-kDa protein which is antigenically related to the RelA subunit. Cell-type-specific differences in IkappaB alpha, -beta, and -gamma were also observed. In transient-transfection experiments, constitutive activity of an NF-kappaB-dependent promoter was observed in MDA-MB-231 and RM22-F5 cells of F phenotype, and this activity was efficiently repressed by cotransfected ER. Since ER inhibits the constitutive as well as inducible activation function of NF-kappaB in a dose-dependent manner, we propose that breast cancers that lack functional ER overexpress NF-kappaB-regulated genes. Furthermore, since recent data indicate that NF-kappaB protects cells from tumor necrosis factor alpha-, ionizing radiation-, and chemotherapeutic agent daunorubicin-mediated apoptosis, our results provide an explanation for chemotherapeutic resistance in ER-negative breast cancers.

Effect of matrix metalloproteinase inhibitor batimastat on breast cancer regrowth and metastasis in athymic mice.

BACKGROUND: Matrix metalloproteinases (MMPs) are involved in the invasion and metastasis of human cancers by mediating the degradation of extracellular matrix components. Therefore, these enzymes constitute promising targets in the development of anticancer therapies. Batimastat ([(4-N-hydroxyamino)-2R-isobutyl-3S-(thienyl-thiomethyl)succinyl]-L- phenyl-alanine-N-methylamide) is one of a new class of agents designed to inhibit MMP activity. PURPOSE: We asked whether batimastat, given as adjuvant therapy after primary tumor resection, could inhibit local-regional tumor regrowth and the formation of lung metastases in a human breast cancer xenograft model. We also explored possible effects of batimastat on breast cancer cell viability and on the accumulation of specific messenger RNAs (mRNAs). METHODS: Human MDA-MB-435 breast cancer cells were treated in vitro for 6 days with batimastat at concentrations ranging from 0.1 to 10.0 microM, and then viable cell counts were performed. The activity of collagenases, directly associated with cultured MDA-MB-435 cells or released into their culture fluids, was assessed by gelatin zymography after 1 and 3 days of batimastat treatment (drug range, 0.2-2.0 microM). Athymic nude mice were given daily intraperitoneal injections of batimastat (30 mg/kg body weight) after resection of MDA-MB-435 primary tumors grown in their mammary fat pads; the volumes of tumor regrowths and the numbers and volumes of lung metastases were calculated; neovascularization in the regrowths was assessed by immunohistochemical analysis with an antibody directed against CD31, an endothelial cell antigen. The effect of batimastat treatment on the accumulation of mRNAs encoding specific MMPs and the tissue inhibitor of metalloproteinases-2 (TIMP-2) in cultured cells, primary tumors, and tumor regrowths was measured by RNA dot blotting and hybridization with complementary probes. Linear regression analysis, Student's t tests, and chi-squared analysis were used to evaluate the data. RESULTS: The viability of cultured MDA-MB-435 cells was not affected by treatment with batimastat; however, measured activities for the 72-kd and 92-kd collagenases released by these cells were reduced after batimastat treatment. Intraperitoneal injection of batimastat significantly inhibited the local-regional regrowth of resected MDA-MB-435 tumors in athymic nude mice (in comparison with control mice, P = .035), and it reduced the incidence (P < .05), number (P = .0001), and total volume (P = .0001) of lung metastases. Batimastat treatment did not affect cellular levels of MMP or TIMP-2 mRNAs. CONCLUSION: Batimastat inhibits human breast cancer regrowth and metastasis in a nude mouse xenograft model. Potential mechanisms for batimastat's inhibitory activity do not include direct cell toxicity or alteration of MMP or TIMP mRNA levels.

Paclitaxel sensitivity of breast cancer cells with constitutively active NF-kappaB is enhanced by IkappaBalpha super-repressor and parthenolide.

The transcription factor nuclear factor-kappaB (NF-kappaB) regulates genes important for tumor invasion, metastasis and chemoresistance. Normally, NF-kappaB remains sequestered in an inactive state by cytoplasmic inhibitor-of-kappaB (IkappaB) proteins. NF-kappaB translocates to nucleus and activates gene expression upon exposure of cells to growth factors and cytokines. We and others have shown previously that NF-kappaB is constitutively active in a subset of breast cancers. In this study, we show that constitutive activation of NF-kappaB leads to overexpression of the anti-apoptotic genes c-inhibitor of apoptosis 2 (c-IAP2) and manganese superoxide dismutase (Mn-SOD) in breast cancer cells. Furthermore, expression of the anti-apoptotic tumor necrosis factor receptor associated factor 1 (TRAF1) and defender-against cell death (DAD-1) is regulated by NF-kappaB in certain breast cancer cells. We also demonstrate that NF-kappaB-inducible genes protect cancer cells against paclitaxel as MDA-MB-231 breast cancer cells modified to overexpress IkappaBalpha required lower concentrations of paclitaxel to arrest at the G2/M phase of the cell cycle and undergo apoptosis when compared to parental cells. The effect of NF-kappaB on paclitaxel-sensitivity appears to be specific to cancer cells because normal fibroblasts derived from embryos lacking p65 subunit of NF-kappaB and wild type littermate embryos were insensitive to paclitaxel-induced G2/M cell cycle arrest. Parthenolide, an active ingredient of herbal remedies such as feverfew (tanacetum parthenium), mimicked the effects of IkappaBalpha by inhibiting NF-kappaB DNA binding activity and Mn-SOD expression, and increasing paclitaxel-induced apoptosis of breast cancer cells. These results suggest that active ingredients of herbs with anti-inflammatory properties may be useful in increasing the sensitivity of cancers with constitutively active NF-kappaB to chemotherapeutic drugs. Oncogene (2000) 19, 4159 - 4169

Dose-intensive chemotherapy in refractory germ cell cancer--a phase I/II trial of high-dose carboplatin and etoposide with autologous bone marrow transplantation.

Between September 1986 and March 1988, 33 patients with refractory germ cell cancer were entered on a phase I/II trial of two courses of high-dose carboplatin plus etoposide with autologous bone marrow support. All patients had extensive prior treatment and had either cisplatin-refractory disease (67%) defined as progression within 4 weeks of the last cisplatin dose or failed at least two cisplatin-based regimens (35%) including a cisplatin-ifosfamide salvage regimen. Patients received a fixed total dose of etoposide of 1,200 mg/m2 with each cycle. The carboplatin dose ranged from 900 mg/m2 to 2,000 mg/m2. Twenty of the 33 patients received the second cycle of therapy. Despite extensive prior therapy with cisplatin, neurotoxicity, nephrotoxicity, or hearing impairment with high-dose carboplatin and etoposide was unusual. The most common nonhematologic toxicity was moderate enterocolitis. The hematologic toxicity of this regimen was substantial at each dose level. All 53 courses were accompanied by granulocytopenic fevers. Seven of the 33 patients (21%) died from treatment. All of these deaths occurred during the granulocyte nadir, and five were related to documented sepsis. Overall, 14 of 32 patients (44%) evaluable for response obtained an objective response, including eight complete remissions. Four patients remain in complete remission, with three patients being continuously free of disease in excess of 1 year. Eight responders (including four complete remissions) had progressed while receiving cisplatin. We conclude that carboplatin and etoposide can be administered in combination at high dosages and this regimen may have curative potential for patients with germ cell tumors resistant to conventional-dose cisplatin-based therapies.

Mechanical stimulation of tissue repair in the hydraulic bone chamber.

A hydraulically activated bone chamber model was utilized to investigate cellular and microstructural mechanisms of mechanical adaptation during bone repair. Woven trabecular bone and fibrotic granulation tissue filled the initially empty chambers by 8 weeks postimplantation into canine tibial and femoral metaphyses. Without mechanical stimulation, active bone remodeling to lamellar trabecular bone and reconstitution of marrow elements were observed between 8 and 24 weeks. In subsequent loading studies, the hydraulic mechanism was activated on one randomly chosen side of 10 dogs following 8 weeks of undisturbed bone repair. The loading treatment applied an intermittent compressive force (18 N, 1.0 Hz, 1800 cycles/day) for durations of a few days up to 12 weeks. Stereological analysis of three-dimensional microcomputed tomography images revealed an increase in trabecular plate thickness and connectivity associated with the loaded repair tissue microstructure relative to unloaded contralateral controls. These microstructural alterations corresponded to an over 600% increase in the apparent modulus of the loaded bone tissue. A significant increase in the percentage of trabecular surfaces lined by osteoblasts immunopositive for type I procollagen after a few days of loading provided further evidence for mechanical stimulation of bone matrix synthesis. The local principal tissue strains associated with these adaptive changes were estimated to range from approximately -2000 to +3000 mustrain using digital image-based finite element methods. This study demonstrates the sensitivity of bone tissue and cells to a controlled in vivo mechanical stimulus and identifies microstructural mechanisms of mechanical adaptation during bone repair. The hydraulic bone chamber is introduced as an efficient experimental model to study the effects of mechanical and biological factors on bone repair and regeneration.

Pressure vs flow triggering during pressure support ventilation.

BACKGROUND: Adult mechanical ventilators have traditionally been pressure- or time-triggered. More recently, flow triggering has become available and some adult ventilators allow the choice between pressure or flow triggering. Prior studies have supported the superiority of flow triggering during continuous positive airway pressure, but few have compared pressure and flow triggering during pressure support ventilation (PSV). The purpose of this study was to compare pressure and flow triggering during PSV in adult mechanically ventilated patients. METHODS: The study population consisted of 10 adult patients ventilated with a mechanical ventilator (Nellcor-Puritan-Bennett 7200ae) in the PSV mode. In random order, we compared pressure triggering of -0.5 H2O, pressure triggering -1 cm H2O, flow triggering of 5/2 L/min, and flow triggering 10/3 L/min. Pressure was measured for 5 min at the proximal endotracheal tube using a data acquisition rate of 100 Hz. From the airway pressure signal, trigger pressure (deltaP) was defined as the difference between positive end-expiratory pressure (PEEP) and the maximum negative deflection prior to onset of the triggered breath. Pressure-time product (PTP) was defined as the area produced by the pressure waveform below PEEP during onset of the triggered breath. Trigger time (deltaT) was defined as the time interval below PEEP during onset of the triggered breath. RESULTS: A pressure trigger of -0.5 cm H2O was significantly more sensitive than the other trigger methods for deltaP, PTP, and deltaT (p<0.001). There was also a significant difference between patients for deltaP, deltaT, and PTP for each trigger method (p<0.001). CONCLUSIONS: For this group of patients, flow triggering was not superior to pressure triggering at -0.5 cm H2O during PSV.

The diagnosis and definition of hepatic malignancies by use of arterial enhanced computerized tomographic scanning.

Axial computerized tomography is a useful tool in the evaluation of either primary or metastatic hepatic neoplasms. An adjunct to this technique is visceral arterial enhanced computerized tomography (AECT). To determine the effectiveness of this modality, bolus intravenous enhanced computerized tomography scans and AECT were compared and correlated to operative findings. Fifty-four consecutive patients were evaluated by AECT and bolus intravenous enhanced computerized tomography over a 30-month period (May 1986 to August 1989) for suspected primary or metastatic hepatic malignancies. Forty-four patients (81%) had hepatic lesions. Fifty-two percent (23 of 44 patients) of the metastatic tumors were from colonic or rectal primary lesions, and 20% were hepatocellular primary lesions. The remainder of the lesions were metastases from a variety of primary lesions. When studies were compared, 34% of the patients (15 of 44 patients) differed in either the location or total number of lesions noted. The lesions of three of the 15 patients (20%) were determined unresectable on the basis of AECT. Of the remaining patients, planned resections were revised in seven patients to either lesser or greater procedures. The number of lesions found at laparotomy equaled the number found by AECT in all but two cases. AECT caused no complications. AECT improved our ability to identify and localize primary and metastatic lesions of the liver. This technique offers the advantage of preoperative definition of the hepatic arterial and portal venous anatomy.

An analysis of perioperative cholangiography in one thousand laparoscopic cholecystectomies.

BACKGROUND: We undertook this retrospective study to ascertain the proper role of perioperative cholangiography in the management of 1002 patients undergoing laparoscopic cholecystectomy for symptomatic cholelithiasis. METHODS: Nine hundred forty-one patients were categorized as being at high or low risk for choledocholithiasis according to the presence or absence of jaundice, pancreatitis, elevated bilirubin, alkaline phosphatase, serum glutamic-oxaloacetic transaminase, or radiographic evidence of common bile duct stones (CBDSs). RESULTS: Intraoperative cholangiography (IOCG) and preoperative endoscopic retrograde cholangiopancreatography (ERCP) were equivalent in the detection of CBDSs, and laparoscopic common bile duct exploration (CBDE) was successful in 12 of the 21 patients (57%) in whom it was attempted. The ducts of the other 52 patients with CBDSs were successfully cleared by preoperative or postoperative ERCP. CONCLUSIONS: Laparoscopic IOCG is successful in detecting CBDS in high-risk patients and half of these ducts can be cleared laparoscopically. The incidence of CBDS in low-risk patients is 1.7%, a risk that does not warrant routine cholangiography. These data suggest ERCP should be reserved for those at-risk individuals in whom IOCG or laparoscopic duct clearance has been unsuccessful.

Growing teratoma syndrome after chemotherapy for germ cell tumors of the ovary.

BACKGROUND: The growing teratoma syndrome has been described with regard to gonadal and extragonadal germ cell neoplasms in males, but few cases have been reported in the female population. In this condition, masses that enlarge during or after chemotherapy are found to contain mature teratoma without malignant elements. CASES: Three patients had either persistent or growing masses despite chemotherapy for germ cell malignancies of the ovary. All cases fit the description of the growing teratoma syndrome. The patients were aged 20-22 years. All three patients had immature teratomas before chemotherapy. The stages of disease ranged from Ia to IIIc. All patients had normal tumor markers while their masses showed growth or persistence. All were free of disease 6-31 months after diagnosis. CONCLUSION: Growth or persistence of a tumor after chemotherapy for malignant teratoma does not necessarily imply progression of malignancy, especially if tumor markers are normal. However, these masses should be resected because they may cause obstruction, compression, or displacement of adjacent organs, or undergo sarcomatous degeneration.

Morphometric and anisotropic symmetries of the canine distal femur.

The purpose of this study was to investigate the homotypical variation in morphologic and anisotropic properties of trabecular bone from paired canine distal femurs. A microcomputed tomography system was used to produce three-dimensional digital reconstructions of the trabecular bone structures. The results showed that the mean bilateral differences in all bone morphology variables were less than 5%. Differences in measures of degree of anisotropy were also less than 5% between matched sites from left and right sides. In general, the bilateral difference in angle of orientation was less than 15 degrees. These data are valuable for calculating the appropriate sample size to use in experiments using the contralateral canine femur as a control. The results and general approach of the study may have significance for the future use of other contralateral trabecular bone sites as controls.

Evaluation of a microcomputed tomography system to study trabecular bone structure.

A new microcomputed tomography (micro-CT) system and thresholding procedure was evaluated as a tool for nondestructive analysis of trabecular bone. Images of 6-mm trabecular bone cubes acquired from the micro-CT system were compared with optical images of corresponding histologic sections to determine the accuracy of representation. The stereologic measures of bone volume fraction (PP) and trabecular plate density (PL) were used to quantify the comparisons. The results showed that the micro-CT measures of PP were not significantly different from those measured from histologic sections and therefore were very accurate. Measures of PL were different by approximately 14%, which translated into discrepancies in trabecular plate thicknesses of about 19 microns. This difference was significantly correlated to the microstructural characteristics of the specific specimen scanned. The precision of both measurements was excellent.

The effect of screw insertion site and unused drill holes on stability and mode of failure after fixation of basicervical femoral neck fracture.

The intent of this biomechanical study is to characterize the effect of unused drill holes and cannulated screw insertion site on the fixation stability and mode of failure after fixation of basicervical femoral neck fractures. Fourteen matched pairs of embalmed human cadaver femora were sorted into four groups according to the level of screw insertion along the lateral cortex. Screws inserted at higher positions along the lateral cortex afforded higher rigidity, thus decreasing the amount of motion at the fracture site. In addition, higher insertion positions reduced the rate of permanent displacement, thus better maintaining reduction. Although all specimens failed at the neck, post-failure inspection revealed upward translation of the inferior screw head when inserted 20 mm below the lesser trochanter. Unused drill holes and guidepin holes had no observed affect on stability or failure mode.

Splanchnic neural regulation of insulin and glucagon secretion in the isolated perfused human pancreas.

The isolated perfused human pancreas was employed as a model in which electrical stimulation of the celiac mixed neural bundle was performed in the presence or absence of selective neural blockers. The insulin and glucagon responses to hyperglycemia alone or in the presence of splanchnic nerve stimulation were similar in magnitude to the results obtained in a preliminary report on isolated human pancreatic function and in studies using animal models. Stimulation of the celiac neural bundle in the presence of hyperglycemia resulted in an inhibition of insulin release and in an augmentation of glucagon release. alpha-adrenergic stimulation resulted in a strong suppression of insulin secretion and a mild suppression of glucagon secretion. beta-adrenergic fiber stimulation caused a mild augmentation of both insulin and glucagon release, whereas the cholinergic fibers strongly stimulated both alpha- and beta-cell secretion. The predominant effects of celiac neural bundle stimulation are insulin inhibition by was of an alpha-adrenergic effect and glucagon stimulation by way of a cholinergic effect. Thus, in this in vitro human model, our data confirm that the splanchnic innervation of the pancreas has a potent regulatory role on pancreatic hormone release in human subjects.

Classification and treatment of local septic complications in acute pancreatitis.

BACKGROUND: An international symposium on acute pancreatitis recently developed a clinical classification system for severe acute pancreatitis that classifies all local septic complications into three groups: infected necrosis (IN), sterile necrosis (SN), and pancreatic abscess (PA). Despite the appeal of having three distinct, well-defined labels for this complex process, the clinical utility of this schema has yet to be determined. The purpose of this study was to investigate the prognostic and therapeutic utility of applying this clinical classification system to a large group of surgical patients with local septic complication from acute pancreatitis. PATIENTS AND METHODS: We reviewed the cases of 62 patients with complicated pancreatitis, classifying them into IN (n = 20), SN (n = 14), or PA (n = 28) groups. Ranson's score, APACHE II score, and computed tomography grading were calculated within the first 48 hours of admission. Information on patient demographics, etiology of pancreatitis, operative procedures, timing of intervention, bacteriology, blood loss, intensive care unit days, ventilator days, and morbidity and mortality were also accrued and analyzed. RESULTS: Despite similar demographics and etiology of pancreatitis, patients with necrosis, both IN and SN, were more critically ill than were patients with PA (APACHE II score > 15, 21% versus 0%, respectively), required earlier operative intervention (mean 14 days versus 29 days, P = 0.02), required necrosectomy with drainage (65% versus 4%, P < 0.001) rather than simple drainage (3% versus 86%, P < 0.001), more reoperations (2.3 versus 1.1, P < 0.05), and had a significantly higher mortality rate (35% versus 4%, P < 0.05). In addition, patients with IN required significantly more hospital days, ventilator days, and blood transfusions than either patients with SN or PA (P < 0.05). CONCLUSIONS: We conclude that this classification system allows for the stratification of patients into three distinct groups--infected necrosis, sterile necrosis, and pancreatic abscess--and has both therapeutic and prognostic usefulness.

Asthma and airway hyper-responsiveness in adults who required hospital admission for bronchiolitis in early childhood.

Viral respiratory infections in infancy may contribute to the development of airway hyper-responsiveness (AHR) in childhood but their effects on respiratory function at the adult age are still uncertain. A group of 42 subjects aged 17-35 with a pediatrician-made diagnosis of severe bronchiolitis in infancy (Br) were compared for the presence of asthma and AHR to a control group (C) paired for age and gender, without evidence of lower respiratory disease in infancy. All had a respiratory and environmental questionnaire, allergy skin prick tests, blood eosinophil count, total serum IgE determination and measurements of expiratory flows and airway response to methacholine. In Br and C groups, respectively, 38 and 12% of subjects had a physician-made diagnosis of asthma, 26 and 7% used bronchodilators and 12 and 0% an inhaled corticosteroid; 71 and 67%, respectively, were atopic, 50 and 24% were smokers and 43 and 17% had a first-degree relative with asthma. Mean baseline FEV1 and FEV1/FVC ratio were lower in the Br than in the C group, with 94/103% (P=0.002) and 80/87 (P<0.0001) of the predicted value, respectively. Geometric mean PC20 methacholine was significantly lower in the Br than in the C group 3.9/20.3 mg ml(-1) (P<0.0001). Mean blood eosinophil count and serum IgE levels were similar in both groups (P> 0.05). In conclusion, asthma and AHR were found more frequently in young adults with a past history of bronchiolitis, suggesting that this type of respiratory infection may contribute to altered pulmonary function in adulthood, although it may also represent an early manifestation of asthma. The influence of potential confounding factors, such as familial predisposition and exposure to cigarette smoke on the development of asthma and AHR in the Br group, cannot be excluded.

Direct calculation of the surface-to-volume ratio for human cancellous bone.

There are many diseases which cause detrimental changes in the trabecular structure of cancellous bone, leading to mechanical failure of the tissue. One approach to understanding the mechanisms of these diseases is to create idealized models that recreate the morphology of the tissue. This paper presents a partial development of such a model. Further histological methods must be developed before a complete definition of morphologically valid models is possible. In a histological section of cancellous bone, the orientation and length of the trabecular surfaces determine how a line drawn across the bone section will intersect the bone-marrow interface. The distribution of the average length between intersections for a set of parallel lines is defined as the mean intercept length distribution. In this paper, the average surface morphology and volume of the average structure of cancellous bone is determined from an examination of the mean intercept length. The average structure of cancellous bone contains a repeated structural element (SE). As a result, the basic bone structure is analogous to a brick wall made from many similar bricks. For a group of 107 specimens, a strong relationship between structural element volume (SE.V) and bone volume fraction (BV/TV) is demonstrated, SE.V = 0.017 kappa (BV/TV)-2.05 mm3, R2 = 0.93, with kappa a model-dependent constant. For the same specimens, the structural element surface (SE.S) showed the relationship, SE.S = 0.144 kappa (BV/TV)-1.35, R2 = 0.92. As a result of the inverse square dependence of structural element volume on bone volume fraction, it is predicted that cancellous bone strength is inversely proportional to structural element volume.

Type I collagen mutation alters the strength and fatigue behavior of Mov13 cortical tissue.

Despite advances in understanding the molecular basis of Osteogenesis Imperfecta, the mechanisms by which type I collagen mutations compromise whole bone function are not well understood. Previously, we have shown that a heterozygous type I collagen mutation is associated with increased brittleness of long bones from Mov13 transgenic mice, a model of the mild form of Osteogenesis Imperfecta. In the current study, we investigated tissue-level damage processes by testing the hypothesis that the fatigue properties of Mov13 tissue were significantly compromised relative to littermate controls. We also quantified tissue structure and mineral content to explain variations in the fatigue behavior. Micro-beam specimens were machined from the anterior and posterior quadrants of Mov13 and control femurs and subjected to cyclic bending at one of four stress levels. Mov13 tissue exhibited a 22-25% reduction in tissue bending strength and a similar reductions in fatigue life and the stress level at which damage was apparent. These results provided tissue-level evidence that damage accumulation mechanisms were significantly compromised in Mov13 cortical tissue. Given that significant alterations in tissue structure were observed in Mov13 femurs, the results of this study support the idea that Mov13 femurs were brittle because alterations in tissue structure associated with the mutation interfered with normal damage processes. These results provide new insight into the pathogenesis of Osteogenesis Imperfecta and are consistent with bone behaving as a damaging composite material, where damage accumulation is central to bone fracture.

The relationship between the structural and orthogonal compressive properties of trabecular bone.

In this study, cubes of trabecular bone with a wide range of structural properties were scanned on a micro-computed tomography system to produce complete three-dimensional digitizations from which morphological and architectural parameters could be measured in a nondestructive manner. The cubes were then mechanically tested in uniaxial compression in three orthogonal directions and to failure in one direction to find the orthogonal tangent elastic moduli and ultimate strengths. After testing, the cubes were weighed and ashed to determine the apparent and ash densities. A high correlation between the basic stereologic measurements was found, indicating that there is a relationship between the amount of bone and number of trabeculae in cancellous bone. Regression analysis was used to estimate the modulus and ultimate strength; these regressions accounted for 68-90% of the variance in these measures. These relationships were dependent on the metaphyseal type and donor, with the modulus also dependent on the direction of testing. This indicates that the properties of the individual trabeculae, as well as their amount and organization, may be important in predicting the mechanical properties of cancellous bone.