Changes in Shear Modulus of the Lumbar Multifidus Muscle During Different Body Positions.

Multifidus function is important for active stabilization of the spine, but it can be compromised in patients with chronic low back pain and other spine pathologies. Force production and strength of back muscles are often evaluated using isometric or isokinetic tests, which lack the ability to quantify multifidi contribution independent of the erector spinae and adjacent hip musculature. The objective of this study is to evaluate localized force production capability in multifidus muscle using ultrasound shear wave elastography (SWE) in healthy individuals. Three different body positions were considered: lying prone, sitting up, and sitting up with the right arm lifted. These positions were chosen to progressively increase multifidus contraction and to minimize body motion during measurements. Shear modulus was measured at the superficial and deeper layers of the multifidus. Repeatability and possible sources of error of the shear modulus measurements were analyzed. Multifidus shear modulus (median (interquartile range)) increased from prone, i.e., 16.15 (6.69) kPa, to sitting up, i.e., 27.28 (15.72) kPa, to sitting up with the right arm lifted position, i.e., 45.02 (25.27) kPa. Multifidi shear modulus in the deeper layer of the multifidi was lower than the superficial layer, suggesting lower muscle contraction. Intraclass correlation coefficients (ICCs) for evaluation of shear modulus by muscle layer were found to be excellent (ICC = 0.76-0.80). Results suggest that the proposed protocol could quantify local changes in spinal muscle function in healthy adults; further research in patients with spine pathology is warranted.

Potential Benefits and Drawbacks of Virtual Clinics in General Surgery: Pilot Cross-Sectional Questionnaire Study.

BACKGROUND: Escalating demand for specialist health care puts considerable demand on hospital services. Technology offers a means by which health care providers may increase the efficiency of health care delivery. OBJECTIVE: The aim of this study was to conduct a pilot study of the feasibility, benefits, and drawbacks of a virtual clinic (VC) in the general surgical service of a busy tertiary center. METHODS: Patient satisfaction with current care and attitudes to VC were surveyed prospectively in the general surgical outpatient department (OPD; n=223). A subset of patients who had undergone endoscopy and day surgery were recruited to follow-up in a VC and subsequently surveyed with regard to their satisfaction (20/243). Other outcomes measured included a comparison of consultation times in traditional and virtual outpatient settings and financial cost to both patients and the institution. RESULTS: Almost half of the patients reported barriers to prospective use of VCs. However, within the cohort who had been followed-up in the VC, satisfaction was higher than the traditional OPD (100% as compared with 187/223, 83.9%). Significant savings in both time (P=.003) and financial costs to patients and the institution were found. CONCLUSIONS: For an appropriately selected group of patients, VCs offer a viable alternative to traditional OPD. This alternative can improve both patient satisfaction and efficiency of patient care.

Particulate air pollution induces progression of atherosclerosis.

OBJECTIVES: We sought to determine the effect of exposure to air pollution particulate matter <10 microm (PM(10)) on the progression of atherosclerosis in rabbits. BACKGROUND: Epidemiologic studies have associated exposure to ambient PM(10) with increased cardiovascular morbidity and mortality. We have previously shown that PM(10) exposure induces a systemic inflammatory response that includes marrow stimulation, and we hypothesized that this response accelerates atherosclerosis. METHODS: Watanabe heritable hyperlipidemic rabbits were exposed to PM(10) (n = 10) or vehicle (n = 6) for four weeks, and bone marrow stimulation was measured. Quantitative histologic methods were used to determine the morphologic features of the atherosclerotic lesions. RESULTS: Exposure to PM(10) caused an increase in circulating polymorphonuclear leukocytes (PMN) band cell counts (day 15: 24.6 +/- 3.0 vs. 11.5 +/- 2.7 x 10(7)/l [PM(10) vs. vehicle], p < 0.01) and an increase in the size of the bone marrow mitotic pool of PMNs. Exposure to PM(10) also caused progression of atherosclerotic lesions toward a more advanced phenotype. The volume fraction (vol/vol) of the coronary atherosclerotic lesions was increased by PM(10) exposure (33.3 +/- 4.6% vs. 19.5 +/- 3.1% [PM(10) vs. vehicle], p < 0.05). The vol/vol of atherosclerotic lesions correlated with the number of alveolar macrophages that phagocytosed PM(10) (coronary arteries: r = 0.53, p < 0.05; aorta: r = 0.51, p < 0.05). Exposure to PM(10) also caused an increase in plaque cell turnover and extracellular lipid pools in coronary and aortic lesions, as well as in the total amount of lipids in aortic lesions. CONCLUSIONS: Progression of atherosclerosis and increased vulnerability to plaque rupture may underlie the relationship between particulate air pollution and excess cardiovascular death.

A novel method to quantify the turnover and release of monocytes from the bone marrow using the thymidine analog 5'-bromo-2'-deoxyuridine.

The present study was designed to develop methods to study the production and release of monocytes from the bone marrow using the thymidine analog 5'-bromo-2'-deoxyuridine (BrdU). Dividing monocytes in bone marrow were labeled with BrdU (MOBrdU), and their release into the blood and disappearance from the circulation were monitored using a double immunostaining method. The first MOBrdU appeared in the circulation 4 h after labeling with BrdU and peaked at 18 h when 34.3 +/- 5.8% of monocytes were labeled. The calculated transit time of monocytes through bone marrow was 38.1 +/- 3.1 h in control rabbits with a half-life (T1/2) of 12.7 h. Instillation of Streptococcus pneumoniae into the lung accelerated the release of monocytes from bone marrow (peak at 10 h) and shortened their bone marrow transit time (27.1 +/- 1.8 vs. 22.6 +/- 0.6, vehicle vs. pneumonia; P < 0.05). We conclude that this nonradioisotope method provides a novel way to monitor monocyte kinetics and confirmed previous reports that a focal pneumonia shortens monocyte marrow transit and increases their release into the circulation.

The effect of interleukin-6 on L-selectin levels on polymorphonuclear leukocytes.

Interleukin-6 (IL-6) shortens the transit time of polymorphonuclear leukocytes (PMN) through the marrow and accelerates their release into the circulation. In contrast to other inflammatory stimuli, this response is associated with a decrease in L-selectin levels on circulating PMN. The present study was designed to determine the effect of IL-6 on L-selectin levels of PMN in rabbits. Recombinant human IL-6 (2 microg/kg) caused a decrease in L-selectin levels on circulating PMN 3 to 12 h after treatment (P < 0.05). L-selectin levels decreased on PMN already in the circulation for up to 4 h (P < 0.05), on PMN released from the marrow posttreatment for up to 12 h (P < 0.01) and on PMN in the marrow for up to 6 h (P < 0.05) after IL-6 treatment. We conclude that IL-6 decreases L-selectin levels on circulating PMN by demarginating PMN with low levels of L-selectin and by releasing PMN from the marrow with low levels of L-selectin. We postulate that this prolonged downregulation of L-selectin on circulating PMN could influence their recruitment into inflammatory sites.

A lung tissue bank for gene expression studies in chronic obstructive pulmonary disease.

A bank of surgically resected human lung tissues frozen at -70 degrees C after being inflated with support medium for cutting frozen tissue and a separate group inflated with fixative and embedded in paraffin has been established for studies of chronic obstructive pulmonary disease. The present report concerns the quality of RNA that can be extracted from these frozen and fixed tissue samples and from cells obtained from them by laser capture microdissection. The results show that the RNA yield was 257+/-183 ng/mg and 77+/-56 ng/mg from randomly selected frozen and paraffin-embedded tissue, respectively. Intact 18S and 28S rRNA subunits were present in 11/23 frozen and 2/6 paraffin-embedded specimens. The 375-bp actin and 296-bp glyceraldehdye 3-phosphate dehydrogenase targets were amplified by reverse transcription-PCR from both sources and the 983-bp glyceraldehdye 3-phosphate dehydrogenase and 499-bp nonhousekeeping integrin-linked kinase targets from frozen tissue. The minimal amount of RNA required for reverse transcription-PCR of 296-bp glyceraldehdye 3-phosphate dehydrogenase target was 29 pg from frozen tissue when RNA subunits were present and 144 pg when these subunits were absent compared to 0.8 ng from paraffin-embedded tissue. Ten laser pulses were required to laser capture sufficient cells from frozen tissue to detect amplification of the 375-bp actin target while more pulses were required for equivalent amplification from paraffin-embedded tissue. Storage time had no detectable effect on RNA quality. We conclude that both frozen and paraffin-embedded tissues as well as laser-captured cells are suitable for gene expression studies but frozen tissue offered greater sensitivity.