Measurement and initial characterization of leukocyte telomere length in 474,074 participants in UK Biobank.

Leukocyte telomere length (LTL) is a proposed marker of biological age. Here we report the measurement and initial characterization of LTL in 474,074 participants in UK Biobank. We confirm that older age and male sex associate with shorter LTL, with women on average ~7 years younger in 'biological age' than men. Compared to white Europeans, LTL is markedly longer in African and Chinese ancestries. Older paternal age at birth is associated with longer individual LTL. Higher white cell count is associated with shorter LTL, but proportions of white cell subtypes show weaker associations. Age, ethnicity, sex and white cell count explain ~5.5% of LTL variance. Using paired samples from 1,351 participants taken ~5 years apart, we estimate the within-individual variability in LTL and provide a correction factor for this. This resource provides opportunities to investigate determinants and biomedical consequences of variation in LTL.

Qualitative analysis: a guide to best practice--forensic science extension.

Qualitative analysis is arguably the cornerstone of analysis since what cannot be recognised cannot be quantified. This is especially true in the case of the forensic sciences where, for example, the mere presence of a prohibited, or controlled, substance in an unauthorized setting is indicative of a potential offence. This paper presents a set of principles of good practice in qualitative analysis. The principles are placed in the context of forensic science and extend earlier published guidance.

The effects of 10 weeks military training on heel ultrasound and bone turnover.

To measure the physiological changes in bone in response to strenuous exercise we performed a prospective study of male army recruits over 10 weeks of basic training. Measurements performed at the start and completion of training consisted of ultrasound (US) measurements of the heel: velocity of sound (VOS in m/seconds) and broadband ultrasound attenuation (BUA in dB/MHz) and bone turnover markers; osteocalcin (OC), bone-specific alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase (TRAP). Forty subjects were recruited for the study and 26 completed training. Over the 10-week study period there was a significant 1.7% fall in mean VOS [mean paired difference (mpd) 27.2 m/second, SEM 9.5 (95% CI 7.5-46.8) P = 0.009] and a nonsignificant 3.4% increase in BUA (P = 0.159). There were significant falls in markers of bone formation OC [11.6%, mpd 0. 11 microg/liter (95% CI 0.07-0.14) P < 0.001] and BALP [13.3%, mpd 3. 49 U/liter (CI 0.80-6.18) P = 0.013] and a nonsignificant 9.5% fall in TRAP a marker of bone resorption. The 10 recruits subsequently injured had a significantly lower VOS on entry [mean difference 24.2 m/seconds (95% CI 4.6-43.7) P = 0.017] and nonsignificantly raised BUA and baseline levels of all bone markers. The ultrasound changes may be accounted for by increase in trabecular separation and a fall in trabecular connectivity due to microfracture. The decrease in bone markers implies a fall in bone turnover.

Measurement of gastrointestinal pH profiles in normal ambulant human subjects.

Gastrointestinal (GI) pH has been measured in 66 normal subjects using a pH sensitive radiotelemetry capsule passing freely through the gastrointestinal tract. Signals were recorded with a portable solid state receiver and recording system, enabling unconstrained measurements with normal ambulatory activities for up to 48 h during normal GI transit. Capsule position in the gut was monitored by surface location using a directional detector. Gastric pH was highly acidic (range 1.0-2.5) in all subjects. The mean pH in the proximal small intestine was 6.6 (0.5) for the first hour of intestinal recording. By comparison the mean pH in the terminal ileum was 7.5 (0.4) (p less than 0.001). In all subjects there was a sharp fall in pH to a mean of 6.4 (0.4) (p less than 0.001) as the capsule passed into the caecum. Values are means (SD). pH then rose progressively from the right to the left colon with a final mean value of 7.0 (0.7) (p less than 0.001).