Muscularity in adult humans: Proportion of adipose tissue‐free body mass as skeletal muscle

Muscularity, or the proportion of adipose tissue‐free body mass (ATFM) as skeletal muscle (SM), provides valuable body composition information, especially for age‐related SM loss (i.e., sarcopenia). Limited data from elderly cadavers suggest a relatively constant SM/ATFM ratio, 0.540 ± 0.046 for men (mean ± SD, n = 6) and 0.489 ± 0.049 for women (n = 7). The aim of the present study was to examine the magnitude and constancy of the SM/ATFM ratio in healthy adults. Whole‐body SM and ATFM were measured using multi‐scan magnetic resonance imaging. The SM/ATFM ratio was 0.528 ± 0.036 for men (n = 139) and 0.473 ± 0.037 for women (n = 165). Multiple regression analysis indicated that the SM/ATFM ratio was significantly influenced by sex, age, body weight, and race. The four factors explained 50% of the observed between individual variation in the SM/ATFM ratio. After adjusting for age, body weight, and race, men had a larger SM/ATFM ratio than women. Both older men and women had a lower SM/ATFM ratio than younger subjects, although the relative reduction was greater in men. After adjustment for sex, age, and body weight, there were no significant differences in the SM/ATFM ratios between Asian, Caucasian, and Hispanic subjects. In contrast, African‐American subjects had a significantly greater SM/ATFM ratio than subjects in the other three groups. In addition, the SM/ATFM ratio was significantly lower in AIDS patients than corresponding values in healthy subjects. Am. J. Hum. Biol. 13:612–619, 2001. © 2001 Wiley‐Liss, Inc.     

Muco-cutaneous colonization and nosocomial infections caused by methicillin-resistant Staphylococcus aureus and Acinetobacter baumanii in intensive care patients

This study was designed to assess the frequency and risk factors for colonization with MRSA and A. baumanii in the intensive care unit, and to analyse the relationship between colonization and infection with MRSA or A. baumanii. During a 24-day survey period, colonization was studied weekly with nasal, throat and digit skin swabs; nosocomial infections were routinely monitored according to CDC recommendations. Clinical data and invasive procedures were registered during a one-year non-epidemic period; 103 ICU patients hospitalized for more than 7 days were prospectively included. We investigated acquired colonization and nosocomial infection with SAMR or A. baumanii for 87 patients not colonized by SAMR or A. baumanii on admission. The colonization acquisition rate was 56% for MRSA and 27% for A. baumanii. Infection incidence (cases per 1,000 patient-days) was 6.46 for MRSA and 1.61 for A. baumanii. On univariate analysis, acquired MRSA colonization was associated with longer ICU stays, longer mechanical ventilation and longer central venous catheterization. Multivariate analysis only showed an association with longer ICU stay. Acquired A. baumanii colonization was associated with SAPSII, longer mechanical ventilation, and longer central venous catheterization in univariate analysis. Multivariate analysis only showed an association with SAPSII and longer mechanical ventilation. In this study, SAMR or A. baumanii infections were not associated with colonization or clinical setting or invasive procedures.     

Cervical specimen order and performance measures of Chlamydia trachomatis diagnostic testing

The orders of three endocervical specimens of 3,561 women for Chlamydia trachomatis testing were randomized to determine whether test performance measures of two nucleic acid amplification tests and a DNA probe were affected by swab order. Specimen collection order did not appear to affect the diagnostic accuracy of these tests.     

High rate of transfer of Staphylococcus aureus from parental skin to infant gut flora

Many Swedish infants carry Staphylococcus aureus in their intestinal microflora. The source of this colonization was investigated in 50 families. Infantile S. aureus strains were isolated from rectal swabs and stool samples at 3 days and at 1, 2, 4, and 8 weeks of age. The strains were identified by using the random amplified polymorphic DNA method and compared to strains from swab cultures of the mothers' hands, nipples, and nares and from the fathers' hands and nares. Maternal stool samples were also obtained at a later stage to compare infant and adult intestinal S. aureus colonization. Although 60% of 1-month-old children had S. aureus in the stools, this was true of only 24% of the mothers. The median population numbers in colonized individuals also differed: 10(6.8) CFU/g of feces among infants at 2 weeks of age versus 10(3.2) CFU/g of feces in the mothers. Of S. aureus strains in the stools of 3-day-old infants, 90% were identical to a parental skin strain. A total of 96% of infants whose parents were S. aureus skin carriers had S. aureus in their feces and 91% had the same strain as at least one of the parents. In comparison, only 37% of infants to S. aureus-negative parents had S. aureus in the stool samples. Thus, infantile intestinal S. aureus colonization was strongly associated with parental skin S. aureus carriage (P = 0.0001). These results suggest that S. aureus on parental skin establish readily in the infantile gut, perhaps due to poor competition from other gut bacteria.     

Papillomas and atypical papillomas in breast core needle biopsy specimens: risk of carcinoma in subsequent excision

We sought to define the risk associated with papillomas and atypical papillomas in breast core needle biopsy specimens from a series of approximately 8,500 biopsies performed during 8 years. From a total of 62 papillary lesions (including papillomas and atypical papillomas), 40 (65%) had histologic follow-up. Overall, 15 (38%) of 40 patients had ductal carcinoma in situ (12 cases) or invasive carcinoma at excision (3 cases). Eight cases diagnosed as papilloma had benign follow-up. Slides were available for review in 38 cases and reclassified into benign papilloma with florid hyperplasia and no or minimal atypia (18 cases), papilloma with separate foci of atypical ductal hyperplasia (7 cases), and severely atypical papillomas "suspicious" for papillary carcinoma (13 cases). Carcinoma was identified in 0 (0%), 2 (29%), and 12 (92%) cases, respectively. We conclude that while atypical papillary lesions and papillomas with associated atypical ductal hyperplasia in breast core needle biopsy specimens are associated with a risk of carcinoma, lesions diagnosed as papilloma or papilloma with no or minimal atypia are benign and do not need to be excised.     

Comparison of in vitro and in vivo alpha/beta ratios for prostate cancer

Parallel in vitro and in vivo studies provide insight into the relationship between clinical response and intrinsic cellular radiosensitivity and may aid in the development of predictive assays. Compilations of radiosensitivity parameters from in vitro experiments can also be used to examine the potential effectiveness of alternative or new treatment plan designs until enough clinical data become available to directly estimate the requisite radiosensitivity parameters. In this work, survival data for six prostate cancer cell lines (ten datasets total) have been extracted from the literature and re-analysed using the linear-quadratic (LQ) survival model. The paired bootstrap technique for regression is used to compute 95% confidence intervals for the estimated radiosensitivity parameters. LQ radiosensitivity parameters derived from the in vitro data are then compared to radiosensitivity parameters derived from clinical data for prostate cancer. Estimates of alpha range from 0.09 to 0.35 Gy(-1) (all cell lines), and the alpha/beta ratio ranges from 1.09 to 6.29 Gy (all cell lines). Point estimates of the repair half-time (PPC-1, TSU-Pr1, PC-3 and DU-145 cell lines) range from 5.7 to 8.9 h (95% confidence interval from 0.26 h to 10.7 h). Differences in the radiosensitivity parameters determined from the data reported by different laboratories are as large as or larger than the differences in radiosensitivity parameters observed among the various prostate cell lines. The reported studies demonstrate that even seemingly small corrections for dose rate effects, such as those expected in high dose rate (HDR) experiments, can sometimes have a significant impact on estimates of alpha and alpha/beta. By neglecting dose rate effects in the analysis of HDR experiments, estimates of the alpha/beta, ratio may be too high by factors as large as 1.3 to 6.2. The half-time for repair derived from the in vitro experiments appears significantly larger (slower repair rate) than estimates derived from the clinical data. However, the prostate radiosensitivity parameters alpha and alpha/beta may be approximately the same in vitro and in vivo. Most of the in vitro data are consistent with an alpha/beta ratio for prostate cancer less than 3 or 4 Gy.     

Reliability and validity of dyspnea measures in patients with obstructive lung disease

Dyspnea, the clinical term for shortness of breath, is the primary symptom and an important outcome measure in evaluations of patients with lung disease. It is a subjective symptom that has proved difficult to quantify. Many dyspnea measures are available, yet it is difficult, based on the existing literature, to determine the most reliable and valid. In this study, we evaluated 6 measures of dyspnea for reliability and validity: (a) Baseline Dyspnea Index (BDI) and Transition Dyspnea Index, (b) UCSD Shortness of Breath Questionnaire (SOBQ), (c) American Thoracic Society Dyspnea Scale, (d) Oxygen Cost Diagram, (e) Visual Analog Scale, and (f) Borg Scale. Subjects were 143 patients (74 women and 69 men) with obstructive lung disease, ages 40 to 86, FEV., 0.36 to 3.53 L, FVC 1.07 to 5.74 L. Dyspnea measures were assessed for test-retest reliability, internal consistency, interrater reliability, and construct validity (i.e.. correlations among dyspnea measures and correlations of dyspnea measures with exercise tolerance, health-related quality of life, lung function, anxiety, and depression). Results suggest that the SOBQ and BDI demonstrated the highest levels of reliability and validity among the dyspnea measures examined. This research was supported by University of California Tobacco Related Disease Research Program Grant 2RT026S, National Heart. Lung, and Blood Institute Grant HL 34732 to Robert M. Kaplan, and National Institutes of Health NHLBI Preventive Pulmonary Academic Award No. HL02215 to Andrew L. Ries.     

Calcium ionophore and chemotactic peptide stimulation of peptidoleukotriene synthesis in DMSO-differentiated HL60 cells

The human promyelocytic leukemia cell line HL60 can be differentiated to mature granulocytes upon exposure to DMSO (1.3%, 6 days). The ability of these cells to metabolize arachidonic acid via the 5-lipoxygenase pathway to form 5-HETE, LTB₄, and 5,12-diHETEs, has been previously documented. However, the production of peptidoleukotrienes by DMSO-differentiated HL60 cells has not been previously reported. Arachidonic acid metabolites produced via 5-lipoxygenase were identified by reverse-phase, high-performance liquid chromatography, immunoreactivity specific for peptidoleukotriene, glutamyl transpeptidase transformation, characteristic UV spectra, and GC mass spectra. Leukotriene synthesis in the DMSO-differentiated HL60 cell is maximal at 5 min when stimulated with the calcium ioniphore, A23187 (1M), in the presence of calcium. These cells produce 12.94±1.8 ng/10⁶ cells of LTC₄ and 3.8±0.4 ng/10⁶ cells of LTB₄. LTC₄ and LTB₄ are also synthesized in the undifferentiated cell when stimulated with 1M A23187 and 1 mM Ca²⁺, but in much smaller quantities, i.e., 1.91±0.42 ng/10⁶ cells of LTC₄ and 0.41 ng±0.06/10⁶ cells of LTB₄. The synthetic chemotactic peptide, f-Met-Leu-Phe, also elicits formation of LTC₄ and LTB₄ in a dose-dependent manner in the presence of exogenously added calcium. Maximal stimulation of DMSO-differentiated cells with f-Met-Leu-Phe produces 2.5±0.2 ng of LTC₄ and 1.45±0.2 ng of LTB₄ per 10⁶ cells. The observation that DMSO-differentiated HL60 cells produce LTC₄, as well as other 5-lipoxygenase products, increases the utility of this cell line for unraveling the regulation of leukotriene biosynthesis by granulocytes.