Response of Old Skeletal Muscle to 8 Weeks of Electrical Stimulation (Should We Change the Conventional Electrical Stimulation Protocol for Cardiomyoplasty?)

We hypothesized that the conditioned muscles of elderly organisms have different responses to electrical stimulation than that of young adult organisms. One-year-old sheep and eight-year-old elderly sheep were used for this investigation. Results. The latissimus dorsi muscle (LDM) of old sheep has less fatigue resistance than LDM of younger animals. In all animals, LDH-5 fractions decreased after eight weeks ES; LDH-1+2 fractions increased. After a two week delay, the data completely returned to baseline values in old adult animals. The percent area occupied by mitochondria in old sheep was less after ES than in younger animals. In all animals, the mitochondrial area increased after ES and reverted to baseline values after the delay. The number of nuclei and fibers considerably increased after ES. Conclusions. Young skeletal muscle obtains more plasticity than adult muscle during ES. Elderly skeletal muscle does not convert to a fatigue resistant state as completely as adult skeletal muscle during a conventional eight week ES protocol. It is necessary to change and prolong the ES protocol for elderly patients

Induction of heart failure: haemodynamic comparison of three different canine models

We compared three methods: arteriovenous anastomosis, doxorubicin administration, and combination of anastomosis and doxorubicin, with the intention of designing a simple, stable model of chronic heart failure. Twelve dogs were divided into three groups of four. One group received carotid-jugular anastomosis (Ana series), another group received anastomosis and doxorubicin injection (A/D series), and the last group received only doxorubicin (Dox series). Animals were followed for eight weeks. Fifteen different haemodynamic parameters were tracked and compared to baseline values. After eight weeks, diastolic pressure in the right atrium increased from 3.8±2.0 mmHg at baseline to 5.3±5.9 mmHg in the Ana series, to 6.3±3.3 mmHg in the Dox series and to 8.0±2.0 mmHg in the A/D series ( P<0.05 A/D vs. baseline). Systolic pulmonary wedge pressure increased from 11.6±2.0 mmHg at baseline to 15.5±3.4 mmHg in the Ana series, 14.0±3.7 mmHg in the Dox series and 17.3±4.2 mmHg in the A/D series ( P = NS vs. baseline). Left ventricular ejection fraction decreased from 53.9±10% at baseline to 36.1±5.6% in the Ana series ( P<0.05 vs. baseline), 31.5±5.4% in the Dox series ( P<0.05 vs. baseline) and 25.8±5.8% in the A/D series ( P<0.001 vs. baseline, P<0.05 vs. Ana series and Dox series). In conclusion, eight weeks are not enough to produce stable heart failure using arteriovenous anastomosis alone. Doxorubicin administration alone produces a left ventricular failure. However, a combination of both of these interventions provides a more stable model of right-and left-sided heart failur

Direct fibrin injection to promote new collateral growth in hind limb ischemia in a rabbit model.

ABSTRACT: Local stimulation of angiogenesis is a new approach for the treatment of critical limb ischemia. Our investigation tested intramuscular (i.m.) injection of a modified fibrin meshwork in a rabbit model. METHODS: The left external iliac and femoral arteries were excised in 24 rabbits that were divided into four groups: control; i.m. saline injection; fibrin meshwork plus low dose (2.5 mg) fibrinogen i.m.; fibrin meshwork plus high-dose (5.0 mg) fibrinogen i.m. Angiography was performed before surgery, immediately after surgery, and one month postoperatively. Lower limb-calf blood pressure was measured immediately after surgery and at postoperative days 10, 20, and 30. On day 30, conventional indirect immunostaining was performed to determine the percentage of the area occupied by capillaries. RESULTS: Immediately after surgery, in all four groups, the number of contract-opacified arteries (COA) crossing a specific segment of a grid decreased from 5.3 +/- 1.3 to 3.2 +/- 1.0 (p \u3c 0.05); the number of grid intersections decreased from 30.2 +/- 6.5 to 19.3 +/- 4.8 (p \u3c 0.05); and the total number of grids with COA decreased from 18.3 +/- 3.8 to 12.2 +/- 2.5 (p \u3c 0.05). One month after surgery, in the control group, these parameters were 6.2 +/- 1.1, 33.2 +/- 5.7 and 20.3 +/- 1.5, respectively; in the saline-treated group, these parameters were 6.1 +/- 0.8, 28.3 +/- 6.9 and 19.8 +/- 1.1, respectively (p \u3e 0.05 versus control and versus baseline data). When fibrin containing 5.0 mg fibrinogen was used, these parameters increased to 8.5 +/- 0.9, 48.3 +/- 5.1, and 27.1 +/- 0.9, respectively (p \u3c 0.001 versus immediately after surgery and p \u3c 0.05 versus control). In all four series, no Doppler flow signal was detected from the posterior tibial artery by day 10. By day 30, the lower limb-calf blood pressure ratio had improved in all four series, but was significantly improved in only the two groups treated with fibrin sealant (0.3 +/- 0.05 control; 0.3 +/- 0.08 saline; 0.6 +/- 0.06 fibrinogen 2.5; 0.7 +/- 0.05 fibrinogen 5.0). CONCLUSION: Intramuscular injection of a fibrin meshwork considerably increased angiogenesis in the severely ischemic hind limb and may be strongly recommended for clinical use in patients with limb-threatening ischemia

Deferoxamine-fibrin accelerates angiogenesis in a rabbit model of peripheral ischemia

The intramuscular (i.m.) injection of a modified fibrin meshwork plus deferoxamine was tested in a rabbit model of acute hind-limb ischemia. After excision of the left external iliac and femoral arteries, 12 rabbits at the Milwaukee Heart Institute were divided into two groups: control and fibrin meshwork plus deferoxamine (FDEF) i.m. The rabbits underwent angiography before surgery, immediately after, and 1 month postoperatively. These data were compiled through counting by means of a grid overlay. Another 12 rabbits at the Vakhidov Center of Surgery, which did not undergo angiography, underwent lower limb-calf blood pressure (L-CBP) measurements made immediately after surgery and at postoperative days 10, 20 and 30. Biopsies from thigh skeletal muscles of rabbits that had L-CBP measurements underwent alkaline phosphatase staining on day 30 to determine the percentage of biopsied area that was occupied by capillaries. The number of arteries and arterioles crossing 71 grid intersections immediately post-surgery decreased from 30.2 +/- 2.3 to 18.0 +/- 2.0 (p \u3c 0.05). One month postsurgery this number increased to 29.2 +/- 2.4 in controls (p \u3c 0.05 vs immediately post-surgery) and to 59.6 +/- 3.2 in the FDEF group (p \u3c 0.001 vs immediately post-surgery). By day 30 the L-CBP ratio improved in the FDEF group (0.8 +/- 0.02) vs controls (0.3 +/- 0.04). By day 30 the capillary density increased from that of normal muscle tissue (198.6 +/- 12.9/mm2) to 292 +/- 12.4/mm2 in the FDEF group (p \u3c 0.05), but decreased in the control group to 98.7 +/- 7.7/mm2. I.m. injection of FDEF considerably accelerated angiogenesis in severely ischemic hind-limb tissue in this model, making it a viable treatment method for clinical use in patients who have critical limb ischemia

Autologous Biological Glue and Aprotinin Prevent Ischemia in Latissimus Dorsi Muscle after Mobilization

The hemodynamic results of cardiomyoplasty, a promising form of surgical treatment for end-stage heart failure, do not support the subjective improvements seen clinically. We hypothesized that this disparity might be due to ischemia-reperfusion injury to the latissimus dorsi muscle (LDM) after mobilization. Having tested autologous biological glue (ABG) as a protective layer around traumatized muscle, as a means for facilitating revascularization, and as a drug depot to reduce local ischemia-reperfusion lesions, we wanted to determine if this protective and revascularization effect could be enhanced by adding aprotinin, a natural inhibitor of serine proteinases with the potential for preventing proteolytic degradation. To test for muscle damage and angiogenesis, we created pockets out of ischemic and nonischemic LDM. The control group had pockets without additives; the second group had pockets with ABG only; and the third had pockets with ABG and aprotinin. Light microscopy revealed that pockets treated with ABG, either alone or with aprotinin, had less leukocyte margination, fibrosis, calcified necrosis, and fibrous degeneration than in controls. In control pockets, after 56 days, capillaries occupied 4.1 ± 0.3 % of the area in nonischemic LDM and 3.6 ± 0.7 % in ischemic LDM (p&gt; 0.05). In pockets treated with ABG only, capillaries occupied 5.5 ± 0.2% (p &lt; 0.05) of the area in ischemic LDM; in pockets treated with ABG and aprotinin, 8.5 ± 1.1% (p &lt; 0.05) area was occupied with capillaries. This data confirmed our hypothesis that aprotinin added to ABG prevents ischemia-reperfusion lesions after muscle mobilization, and enhances capillary ingrowth in both the ischemic muscle and the interlayer between ischemic and nonischemic muscle. Key words: cardiomyoplasty, LDM ischemia, autologous biological glue, aprotinin

Effect of electrical stimulation on arteriogenesis and angiogenesis after bilateral femoral artery excision in the rabbit hind-limb ischemia model

The effects of electrical stimulation (ES) on arteriogenesis (the opening of preexisting collaterals) and angiogenesis (formation of new capillaries) were studied after acute bilateral hind limb ischemia was induced via bilateral femoral artery excision in a rabbit model. The study evaluated the rabbit hind limbs\u27 normal response to acute ischemia and to application of ES by calculating changes in arterial and capillary densities. Comparisons were made with our prior study, in which the femoral artery was unilaterally excised, as we attempted to expand on the topics of arteriogenesis and angiogenesis. Twelve adult New Zealand white rabbits were randomly assigned to 1 of 2 series. In Series 1, the control group, both femoral arteries were excised and no ES was applied. In Series 2, both femoral arteries were excised and ES was applied to the left limb. One lead was implanted into the left adductor muscle near the site of the excised left femoral artery (Series 2), and a stimulator (Thera, Medtronic, Inc, Minneapolis, MN) was implanted in a separate pocket. ES was applied at a rate of 3 V, 30 contractions per minute, beginning immediately after surgery and continuously for 1 month. Angiography was performed in all 12 rabbits 1 month after surgery to establish the anatomy of the collateral vessels and to demonstrate that the femoral artery stump continued to be an end artery. Contrast-opacified arteries (COAs) that crossed the grid\u27s midline, and the total number of grid lines intersected by COAs, were tallied according to an established method. Capillary density was calculated as the number of capillaries per square millimeter of muscle. In Series 1, after 1 month, the number of COAs crossing the grid\u27s midline was 4.5 +/-1.5 on the left and 4.8 +/-1.2 on the right side. In Series 2, the number of COAs crossing the grid\u27s midline was 7.9 +/-1.8 on the left side (

Common colorectal cancer risk alleles contribute to the multiple colorectal adenoma phenotype, but do not influence colonic polyposis in FAP

The presence of multiple (5-100) colorectal adenomas suggests an inherited predisposition, but the genetic aetiology of this phenotype is undetermined if patients test negative for Mendelian polyposis syndromes such as familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP). We investigated whether 18 common colorectal cancer (CRC) predisposition single-nucleotide polymorphisms (SNPs) could help to explain some cases with multiple adenomas who phenocopied FAP or MAP, but had no pathogenic APC or MUTYH variant. No multiple adenoma case had an outlying number of CRC SNP risk alleles, but multiple adenoma patients did have a significantly higher number of risk alleles than population controls (P=5.7 × 10(-7)). The association was stronger in those with ≥10 adenomas. The CRC SNPs accounted for 4.3% of the variation in multiple adenoma risk, with three SNPs (rs6983267, rs10795668, rs3802842) explaining 3.0% of the variation. In FAP patients, the CRC risk score did not differ significantly from the controls, as we expected given the overwhelming effect of pathogenic germline APC variants on the phenotype of these cases. More unexpectedly, we found no evidence that the CRC SNPs act as modifier genes for the number of colorectal adenomas in FAP patients. In conclusion, common colorectal tumour risk alleles contribute to the development of multiple adenomas in patients without pathogenic germline APC or MUTYH variants. This phenotype may have 'polygenic' or monogenic origins. The risk of CRC in relatives of multiple adenoma cases is probably much lower for cases with polygenic disease, and this should be taken into account when counselling such patients