Lacunar-canalicular network in femoral cortical bone is reduced in aged women and is predominantly due to a loss of canalicular porosity

The lacunar-canalicular network (LCN) of bone contains osteocytes and their dendritic extensions, which allow for intercellular communication, and are believed to serve as the mechanosensors that coordinate the processes of bone modeling and remodeling. Imbalances in remodeling, for example, are linked to bone disease, including fragility associated with aging. We have reported that there is a reduction in scale for one component of the LCN, osteocyte lacunar volume, across the human lifespan in females. In the present study, we explore the hypothesis that canalicular porosity also declines with age. To visualize the LCN and to determine how its components are altered with aging, we examined samples from young (age: 20–23 y; n = 5) and aged (age: 70–86 y; n = 6) healthy women donors utilizing a fluorescent labelling technique in combination with confocal laser scanning microscopy. A large cross-sectional area of cortical bone spanning the endosteal to periosteal surfaces from the anterior proximal femoral shaft was examined in order to account for potential trans-cortical variation in the LCN. Overall, we found that LCN areal fraction was reduced by 40.6% in the samples from aged women. This reduction was due, in part, to a reduction in lacunar density (21.4% decline in lacunae number per given area of bone), but much more so due to a 44.6% decline in canalicular areal fraction. While the areal fraction of larger vascular canals was higher in endosteal vs. periosteal regions for both age groups, no regional differences were observed in the areal fractions of the LCN and its components for either age group. Our data indicate that the LCN is diminished in aged women, and is largely due to a decline in the canalicular areal fraction, and that, unlike vascular canal porosity, this diminished LCN is uniform across the cortex.

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The lacunar-canalicular network (LCN) is reduced by 40.6% in aged women

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The lacunar density (lacunae number per given area of bone) is reduced by 21.4% in aged women

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The reduction in LCN in aged women is primarily due to a 44.6% loss of canaliculi

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No endosteal vs. periosteal regional differences were observed in the LCN and its components in either young or aged women

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A reduction in canaliculi with age may contribute to bone fragility in aged women

The value of end-tidal CO2 monitoring when comparing three methods of conscious sedation for children undergoing painful procedures in the emergency department

BACKGROUND

Many studies have evaluated conscious sedation regimens commonly used in pediatric patients. Recent advances in capnography equipment now enable physicians to assess respiratory parameters, specifically end-tidal CO2 (et-CO2), more accurately in spontaneously breathing sedated children than was possible in the earlier studies. This study was designed to: 1) compare the safety and efficacy of intravenous fentanyl, intravenous fentanyl combined with midazolam, and intramuscular meperidine-promethazine-chlorpromazine (MPC) compound when used for painful emergency department (ED) procedures: and 2) to determine whether the addition of et-CO2 monitoring enabled earlier identification of respiratory depression in this population.

METHODS

Forty-two children requiring analgesia and sedation for painful ED procedures were randomly assigned to receive either fentanyl, fentanyl-midazolam, or MPC compound. Vital signs, oxygen saturation, and et-CO2 were monitored continuously. Pain, anxiety, and sedation scores were recorded every five minutes.

RESULTS

Respiratory depression (O2 saturation < or = 90% for over the minute or any et-CO2 > or = 50) occurred in 20% of fentanyl, 23% of fentanyl-midazolam, and 11% of MPC patients (P = NS). Of those patients manifesting respiratory depression, 6/8 were detected by increased et-CO2 only. MPC patients required significantly longer periods of time to meet discharge criteria than fentanyl and fentanyl-midazolam patients (P < 0.05). No differences were noted in peak pain, anxiety, or sedation scores.

CONCLUSIONS

Fentanyl, fentanyl-midazolam, and MPC produced a high incidence of subclinical respiratory depression. End-tidal CO2 monitoring provided an earlier indication of respiratory depression than pulse oximetry and respiratory rate alone. MPC administration resulted in a significantly delayed discharge from the ED.

Lidocaine for lumbar punctures. A help not a hindrance

OBJECTIVE

To determine whether premedication for lumbar puncture (LP) with lidocaine hinders collection of cerebrospinal fluid (CSF) through either increased number of attempts or increased incidence of traumatic punctures.

DESIGN

A randomized controlled trial.

SETTING

The pediatric emergency department of an innercity teaching hospital.

PATIENTS

A convenience sample of 100 children, younger than 3 years, who required an LP as part of their diagnostic workup.

INTERVENTION

Patients were randomized to receive either lidocaine or no local anesthetic before undergoing an LP.

MAIN OUTCOME MEASURES

Comparison of the number of attempts needed to obtain CSF and the number of traumatic LPs between the lidocaine-treated and no local anesthetic groups.

RESULTS

The 51 patients randomized to receive lidocaine did not differ markedly in age from the 49 patients randomized to receive no local anesthetic. Ease of obtaining CSF, as measured by number of attempts, did not differ with 59% of the patients in each group requiring 1 attempt. Defining a traumatic LP as more than 1000 x 10(6)/L red blood cells in the CSF showed notably more traumatic LPs in the lidocaine-treated group. Defining a traumatic LP as one with more than 10,000 x 10(6)/L red blood cells in the CSF showed no significant difference in the number of traumatic LPs whether or not the patient was premedicated with lidocaine. The level of experience of the physician performing the LP did not affect the outcome.

CONCLUSIONS

Premedication with lidocaine for an LP does not binder the ease of obtaining CSF. The clinical relevance of a greater number of traumatic LPs in the lidocaine-treated group is questionable because this finding is negated when traumatic is defined as more than 10,000 x 10(6)/L CSF red blood cells. Based on these results, we advocate premedication with a local anesthetic when an LP is performed in the pediatric emergency department.

Plasma beta-endorphin responses to one-hour bicycling and running at 60% VO2max

Ten adult male volunteers were studied to examine the effect on plasma beta-endorphin (B-EN) of bicycling and running for 1 h at 60% VO2max. All subjects were physically active and accustomed to both exercise modes (mean VO2max in ml X kg-1 X min-1; bicycling, 54; running, 59). Following preliminary VO2max tests, subjects participated in randomly ordered experimental sessions of bicycling and running for 1 h at loads requiring 60% of their mode-specific VO2max. Five subjects also participated in control sessions. Blood samples were collected immediately pre- and immediately post-exercise, and hematocrits were determined. Samples were centrifuged, separated, and plasma was stored at -50 degrees C until analysis for B-EN. Analysis involved separation of B-EN from beta-lipotropin by short column chromatography followed by radioimmunoassay. Despite an observed trend for elevated B-EN following exercise, there were no significant pre- to post-exercise differences (P greater than 0.05) in mean B-EN levels in any of the three sessions. Expressed as percentage change in B-EN, there were no significant differences between bicycling, running, or control. These results indicate that 1 h bicycling or running exercise at 60% VO2max does not consistently increase B-EN, and that responses are variable between individuals.

Classifying women alcoholics by Cattell's 16PF. A preliminary investigation of an alcoholic typology

Factor analysis of 16PF scores of 146 women alcoholics produced 6 factors which accounted for over 50% of the variance. The 6 personality types are described.

An application of the multidimensional model of alcoholism to program effectiveness. Rehabilitation status and outcome

Five months after treatment, five groups of alcoholics achieved varying levels of need satisfaction on measures of rehabilitation status and income, but showed no differences on measures of drinking status.

An application of the multidimensional model of alcoholism. Differentiation of alcoholics by mode analysis

Cluster analysis of the responses of 563 alcoholics on the Human Services Scale revealed 5 homogeneous groups.