Developmental changes in the regulation of smooth muscle contraction were examined in urinary bladder smooth muscle from mice. Maximal active stress was lower in newborn tissue compared with adult, and it was correlated with a lower content of actin and myosin. Sensitivity to extracellular Ca2+ during high-K+ contraction, was higher in newborn compared with 3-wk-old and adult bladder strips. Concentrations at half maximal tension (EC50) were 0.57 ± 0.01, 1.14 ± 0.12, and 1.31 ± 0.08 mM. Force of the newborn tissue was inhibited by ∼45% by the nonmuscle myosin inhibitor Blebbistatin, whereas adult tissue was not affected. The calcium sensitivity in newborn tissue was not affected by Blebbistatin, suggesting that nonmuscle myosin is not a primary cause for increased calcium sensitivity. The relation between intracellular [Ca2+] and force was shifted toward lower [Ca2+] in the newborn bladders. This increased Ca2+ sensitivity was also found in permeabilized muscles (EC50: 6.10 ± 0.07, 5.77 ± 0.08, and 5.55 ± 0.02 pCa units, in newborn, 3-wk-old, and adult tissues). It was associated with an increased myosin light chain phosphorylation and a decreased rate of dephosphorylation. No difference was observed in the myosin light chain phosphorylation rate, whereas the rate of myosin light chain phosphatase–induced relaxation was about twofold slower in the newborn tissue. The decreased rate was associated with a lower expression of the phosphatase regulatory subunit MYPT-1 in newborn tissue. The results show that myosin light chain phosphatase activity can be developmentally regulated in mammalian urinary bladders. The resultant alterations in Ca2+ sensitivity may be of importance for the nervous and myogenic control of the newborn bladders.

Systemic hyperbaric oxygen (HBO) is accomplished when a patient is breathing 100% oxygen in an environment with increased barometric pressure. A typical HBO treatment protocol of diabetic foot ulcer involves 20 to 40 sessions. Treatment is usually given as daily 90- to 120-minute HBO sessions at pressures between 2.0 and 2.5 absolute atmospheres. The wide use of HBO as treatment of diabetic foot ulcers over the past decades has been founded on weak scientific ground (ie, few and small prospective studies with methodologic limitations on top of case series). However, the consistency in positive outcome in these trials evaluating HBO on ulcer healing is noteworthy because these findings are in concert with data from in vitro and physiologic studies supporting the theoretic framework of HBO reversing hypoxia-induced pathology. Two well-designed randomized double-blinded placebo-controlled studies have in recent years put HBO on firmer ground as treatment of a selection of diabetic patients with chronic foot. Some evidence indicates that microvascular parameters such as transcutaneous (partial) oxygen pressure (TcPO(2)) could be useful in predicting which patients will benefit from therapy. Health economic studies suggest potential cost-effectiveness of HBO. But because these analyses are limited by their deficient primary clinical data, they should be interpreted with caution. Thus, HBO is only indicated in a selected group of patients with chronic diabetic foot ulcers. Several key issues remain to be addressed such as developing robust criteria to determine which patients are likely to benefit and when to start and stop treatment.

The aims of this study were to investigate whether hypertrophy of the small intestinal smooth muscle leads to alterations of myosin isoform composition and shortening velocity and whether possible changes correlate with a change in the sensitivity to ADP of shortening velocity in this tissue. A partial occlusion was introduced in the distal part of the ileum of guinea‐pigs. After 2 weeks, the part of the small intestine just proximal of the stenosis was hypertrophied (indicated by a significantly increased cross‐sectional area). The most proximal part of the small intestine was used as control, thus enabling comparisons between hypertrophic and normal tissue from the same animal. The outer longitudinal layer of the intestinal wall was gently peeled off and used for biochemistry, RT‐PCR and mechanical experiments. The desmin/actin ratio was significantly increased following hypertrophy, although myosin and actin expression were similar in control and hypertrophic tissue. In hypertrophic tissue, the myosin heavy chain mRNA with a 21 base pair insert decreased significantly. The composition of the mRNA encoding the myosin essential light chains changed towards more of the basic type (LC17b). No change in the expression of non‐muscle myosin heavy chains A and B was detected. The maximal shortening velocity (Vmax) of maximally activated skinned preparations was significantly lower in the hypertrophic tissue (≈50 % of control). The sensitivity of Vmax to ADP was increased in the hypertrophic smooth muscle tissue. We conclude that myosin expression is altered following intestinal hypertrophy and that these alterations affect reactions in the cross‐bridge interaction, leading to a slower and more economical contractile function.

Aims To investigate whether multi-frequency measurement of vibration perception thresholds (VPTs) can identify individuals with a high risk of developing diabetic foot ulcer or neuropathic symptoms. Methods VPTs were measured at six different frequencies (4, 8, 16, 32, 64 and 125 Hz) on metatarsal heads 1 and 5 on the sole of the foot using a standard VibroSense Meter device in 535 type 1 diabetic (T1DM) patients and 717 non-diabetic control subjects. VPTs in control subjects were used to establish normal values for five different age groups for male and female subjects respectively. Normal values were defined as a VPT below the mean plus 1.66 x standard deviation for each group. Various definitions of abnormal VPTs were tested using either all frequencies, only lowest VPT frequencies (4 and 8 Hz) or only highest VPT frequencies (64 and 125 Hz). Results The VPTs were higher in T1DM patients than in non-diabetic control subjects matched for age and gender. The low frequencies, 4 and 8 Hz, particularly were associated with the risk of diabetic foot ulcer (OR 40.7 [5.4–308.4], p = 0.0003) and with difficulties in balance and or gait (OR 1.89 [1.04–3.46], p = 0.04) difficulties and weakness (OR 2.77 [1.25–6.16], p = 0.01). The VPTs at the 125 Hz frequency were higher in short duration (≤ 10 yrs.) T1DM patients compared to age- and gender-matched control subjects. Conclusions Vibration perception thresholds at low frequencies seem to be a better indicator of the risk of developing diabetic foot ulcers, gait or balance problems or weakness of the foot. The 125 Hz frequency, however, seemed to be impaired earlier and it was the only pathological VPT frequency in patients with short duration of diabetes.This study suggests that at least four different frequencies (4, 8, 64 and 125 Hz) should be included in any examination in order to obtain a complete evaluation of the risk factors for diabetic neuropathy and diabetic foot ulcers.

Aims/hypothesis The increased all-cause mortality in patients with chronic diabetic foot ulcers cannot fully be explained by traditional cardiovascular risk factors. The significance of heart-rate-corrected QT (QTc) prolongation, a finding often seen in these patients, is unknown. Recently, the importance of metabolic control and hypoglycaemia has been discussed. The aim of this study was to evaluate the impact of different HbA 1c levels and QTc prolongation on all-cause mortality in the high-risk population of patients with type 2 diabetes mellitus and foot ulcers. Methods All patients with type 2 diabetes, younger than 80 years, visiting our diabetes foot unit, with a foot ulcer duration >4 weeks, were screened for participation. Patients on dialysis were excluded. Patients were grouped according to HbA 1c level and QTc time ≤ or >440 ms. Results Patients (n=214, median age 69.1 years) were grouped according to HbA 1c level (HbA 1c <7.5% [<58 mmol/mol] n=81, 7.5-8.9% [58-74 mmol/mol] n=70, >8.9% [>74 mmol/ mol] n=63). Baseline characteristics, including use of potential hypoglycaemic drugs, were similar between groups. During the 8 years of follow-up 151 patients died (70.6%) and HbA 1c < 7.5% (<58 mmol/mol) was strongly associated with increased mortality. The highest mortality was seen in patients with a combination of HbA 1c <7.5% (<58 mmol/mol) and QTc prolongation, with an 8 year mortality of 92.1% as compared with 48.8% in those with HbA 1c < 7.5% (<58 mmol/mol) but without QTc prolongation. Conclusion/interpretations HbA 1c <7.5% (<58 mmol/mol) in a high-risk population of patients with type 2 diabetes and foot ulcers is associated with a significantly higher mortality, particularly in patients with QTc prolongation.

AimsAnkle–brachial index (ABI) is the most commonly used test when diagnosing peripheral vascular disease and is considered a marker for cardiovascular risk. Transcutaneous oxygen pressure (TcPO2), a test associated with microvascular function, has in several studies shown better correlation with diabetic foot ulcer (DFU) healing. Whether a low TcPO2 could be a marker for mortality in the high-risk population of DFU patients has not been evaluated before. The aim of this study was to evaluate the predictive value of TcPO2 in comparison with ABI and toe blood pressure (TBP) on 1-year mortality in type 2 diabetes patients with DFU.MethodsType 2 diabetes patients aged ≤ 90 years, with one DFU who attended our multidisciplinary DFU-unit during year 2013–2015 and were screened with TcPO2, ABI and TBP were retrospectively evaluated. One-year mortality was assessed from the national death register in Sweden.ResultsA total of 236 patients (30% women) with a median age of 76 (69–82) years were evaluated in this study. Within 1 year, 14.8% of the patients died. TcPO2 < 25 mmHg was associated with a higher 1-year mortality compared with TcPO2 ≥ 25 mmHg (27.7 vs. 11.6%, p = 0.003). TBP and ABI did not significantly influence 1-year mortality. In a Cox regression analysis adjusted for confounders, TcPO2 was independently predicting 1-year mortality with a hazard ratio for TcPO2 < 25 mmHg of 2.8 (95% CI 1.34–5.91, p = 0.006).ConclusionsThis study indicates that a low TcPO2 is an independent prognostic marker for 1-year mortality among patients with type 2 diabetes and DFU.

Aims A diabetic foot ulcer (DFU) is associated with increased cardiovascular risk and mortality, independently of ulcer etiology (ischemic, neuro-ischemic or neuropathic). Ankle–brachial index (ABI) is the most commonly used test when diagnosing peripheral macrovascular disease and is a well-known marker for increased cardiovascular risk. Transcutaneous oxygen pressure (TcPO2) is considered to better evaluate microvascular function and has in previous studies shown correlations with both wound healing and survival. The aim of this study was to evaluate the combined impact of a low TcPO2 (<30 mmHg) and a pathological ABI (<0.9 or ≥1.4) on three-year mortality in patients with DFU. Methods Type 2 diabetes patients aged <90 years, with at least one DFU who underwent vascular assessment with ABI and TcPO2 were screened for participation. The primary endpoint was mortality after three years, assessed from the National Death Registry in Sweden. Results The study enrolled 235 participants with a median age of 76 years. Individuals with either an abnormally high or low ABI in combination with a low TcPO2 had the worst survival rates, with three-year mortality of 54%, compared to 42% in those with one abnormal variable (either ABI or TcPO2), and 21% in those with normal ABI and TcPO2. Conclusions Combining ABI and TcPO2 when risk stratifying DFU patients seems to provide additional predictive information, not only concerning ulcer healing and limb salvage, but also on survival.

Information on the effects of thyroid hormone on smooth muscle contractile protein expression and mechanical properties is sparse. We have addressed the following questions. (1) Can thyroxine hormone alter myosin isoform composition in smooth muscle? (2) Can a change in myosin isoform composition lead to altered mechanical properties in smooth muscle? (3) Are alterations, if occurring, equal in fast and slow smooth muscle types? Guinea‐pigs were treated with thyroxine (T4) for 12 days. Control animals were given physiological saline solution. Maximal unloaded shortening velocity (Vmax) was measured in chemically skinned, maximally activated muscle preparations from the aorta and the taenia coli. Vmax increased following thyroxine treatment, by approximately 20 % in the taenia coli. In the aorta, no significant increase in Vmax could be detected. The sensitivity of isometric force to inorganic phosphate (Pi) was increased in the taenia coli following thyroxine treatment. The expression of mRNA (determined with RT‐PCR) for the myosin heavy chain with the seven amino acid insert increased by approximately 70 % in the aorta and about 25 % in the taenia coli following thyroxine treatment. Western blot analysis showed an increase in the inserted myosin heavy chain form in the taenia coli. Expression of mRNA for the myosin essential light chains and the corresponding proteins did not change significantly in either muscle type. No alterations in non‐muscle myosin heavy chain isoforms could be detected after thyroxine treatment. In conclusion, thyroxine treatment alters the isoform composition of myosin in fast and slow smooth muscles in vivo. This change is sufficient to increase shortening velocity and sensitivity of isometric force to Pi in the fast, but not in the slow, smooth muscle type.