The atrioventricular node and bundle in the ferret heart: A light and quantitative electron microscopic study

The cells of the atrioventricular (AV) junction in the ferret heart were examined using light microscopy, a wax-model reconstruction and quantitative electron microscopy to determine their organization and characteristics. A series of subdivisions of the specialized tissues of the AV junction was apparent at both the light and electron microscopic levels. A transitional zone was observed interposed between the atrial muscle cells and the AV node. The AV node consisted of a coronary sinus portion, a superficial portion and a deep portion. The AV bundle had a segment above the anulus fibrosus, a segment which penetrated the right fibrous trigone, a non-branching segment below the anulus fibrosus and a branched segment. At the ultrastructural level the AV junctional conduction tissues had fewer irregularly oriented myofibrils than did working atrial myocardial cells. T-tubules, present in atrial muscle cells, were not observed in the modified muscle cells of the AV node and bundle. Conventional intercalated discs also were not observed between the cells of the AV node or the AV bundle. Atrial myocardial cells had the highest percentage of the plasma membrane occupied by desmosomes, fasciae adherentes and gap junctions. The AV bundle cells had the highest percentage of appositional surface membrane and a relatively large fraction of plasma membrane occupied by gap junctions. Cells of the superficial portion of the AV node had the smallest percentage of the plasma membrane composed of gap junctions, desmosomes or fasciae adherentes, as well as the smallest fraction of the cell membrane apposed to adjacent cells. The stereological data indicate that the most useful distinguishing characteristic between atrial muscle cells and conduction cells was that a smaller percentage of the conduction cell sarcoplasm was occupied by mitochondria and myofibrils. The most useful characteristics that could be used to differentiate between the regions of the AV junctional conduction tissues were the amounts and types of surface membrane specializations in the respective cell types.     

The impact of decentralisation on the performance of health care systems: a non-linear relationship

The European Journal of Health Economics - This paper examines the role of institutions—notably the degree of administrative decentralisation across levels of government—in health care...     

Effects of intraperitoneal Ringer's lactate instillation and infusion on postsurgical adhesion formation

We compared the effects of continuous Ringer's lactate infusion and Ringer's lactate instillation on postsurgical adhesion formation in the rat model. The results show that intraperitoneal Ringer's lactate instillation reduces postsurgical adhesions. However, its efficacy is not improved by additional infusion of Ringer's lactate.     

Cyfra 21-1 - a new tumor-marker for lung-cancer

Among 20 known cytokeratins, cytokeratin fragment 19 is a 40 kD acidic molecule whose distibution is restricted to simple or pseudo-stratified epitelia, such as the epithelial layer of the bronchial tree. An immunoradiometric assay, CYFRA 21-1, was used to detect a fragment of cytokeratin 19 in the serum of 90 subjects and compared with serum levels of CEA, NSE and TPA. Sixty-seven consecutive patients with lung cancer and 23 healthy subjects were tested. Cut-off values for tumor markers were considered as the 95% of specificity versus controls. There were 32 adenocarcinomas, 29 squamous carcinomas and 6 other tumors. Increased serum levels of CYFRA 21-1 were found in lung cancer patients compared to controls [1.6 (0.2-3.2) versus 0.5 (0.2-1.8): p<0.001]. In our study TPA was more sensitive than CYFRA 21-1: 49% versus 40%; when we combined both markers the sensitivity increased to 63%. Significant difference in values were found before and after surgery in serum levels of 34 operated patients: p<0.01. We found higher levels of soluble cytokeratin 19 in lung cancer patients and in the adenocarcinoma subgroup. This study does not support the exclusive use of soluble cytokeratin 19 as a specific marker of lung cancer and not only in squamous carcinoma subgroup. This suggested that diagnostic and prognostic sensitivity increase when CYFRA 21-1 and TPA or other markers are combined.     

Treatment of Vitamin B12 Deficiency after Gastric Surgery for Severe Obesity

Background: Vitamin B₁₂ deficiency after gastric surgery for obesity is due to a failure of separation of vitamin B₁₂ from protein foodstuffs and to a failure of absorption of crystalline vitamin B₁₂ in the presence of intrinsic factor. The purpose of this study was to determine which of four oral doses of crystalline vitamin B₁₂ was most effective in treating vitamin B₁₂ deficiency in 102 patients. Methods and Results: At time of entry into the study, the patients had a serum vitamin B₁₂ < 100 pmol L ⁻¹, were 29.9 ± 21.7 months post-op, were 37 ± 8 years old and had a body mass index of 30 ± 6 kg m⁻². Eight (8%) had had a vertical banded gastroplasty and 94 (92%) a gastric bypass. For the first 3 months all patients received 350 μg per day of crystalline vitamin B₁₂ and all increased their serum vitamin B₁₂ levels to over 100 pmol L⁻¹. The patients were then assigned to receive for a further 3 month period one of four oral doses of crystalline vitamin B₁₂-100 μg, 250 μg, 350 μg and 600 μg. Serum vitamin B₁₂ levels were greater than 150 pmol L⁻¹ after 6 months in 83.3% of patients who received 100 μg; 92.3% of patients who received 250 μg; 94.7% after 350 μg and 95.2% after 600 μg (p%0.525). Conclusion: At least 350 μg per day is the appropriate oral dose of crystalline vitamin B₁₂ after gastric surgery for obesity to correct low serum vitamin B₁₂ levels in 95% of patients.     

Surfactant replacement therapy: a multicentric trial comparing two dosage approaches

This is an interim analysis of a multicentric trial that took place in 7 Neonatal Units to compare two initial doses of exigenous pulmonary surfactant (100 mg/kg and 200 mg/kg of phospholipids)by using a porcine surfactant for the treatment of very severe Hyaline Membrane Disease. The initial higher dose produced better oxigenation of arterial blood, reducing the time in high oxygen concentrations,while retreatments were necessary in less than half of the infants receiving 200 mg/kg as initial dose. The protocol of this study allowed the administration of additional doses only when FiO(2) was equal or greater than 0.40 instead of > 0.21, as in a large study recently published, where the same initial doses were given. This resulted in more than 40% reduction in the amount of surfactant administered,with apparently similar clinical outcome.     

Evaluation of compensation filters in pedal radiographs

Compensation filters allow increased visibility of detail in chest, shoulder, spine, hip, knee, and foot radiographs. This study examines use of an anatomic compensation filter to improve imaging in pedal radiographs. Anteroposterior radiographs were obtained of 25 cadaveric feet at two settings with and without the compensation filter. Densitometer readings were taken at ten forefoot anatomic sites. The compensation filter produced statistically significant reductions in densitometer readings at all anatomic sites and at both radiographic settings. Filtration improved imagery of bony structures, provided excellent soft-tissue visualization, and lowered patient exposure.     

Flow capacity of inferior epigastric artery in composite arterial grafts

BACKGROUND: In the effort to expand the use of arterial conduits for myocardial revascularization, 'Y-graft' techniques are utilized with increasing frequency, although the physiology of this type of composite arterial grafts is not yet fully understood. The aim of this study was to measure changes in blood flow through a 'Y-graft' constructed by anastomosing a segment of inferior epigastric artery (IEA) off the side of an in situ internal thoracic artery (ITA). METHODS: Twenty-two patients who underwent CABG were enrolled in this prospective study. Exclusion criteria were age > 70 years, poor left ventricular function (Ejection Fraction < 0.25) and need for associated cardiac procedures. Blood flow in the TrA-IEA 'Y-graft' was measured in the operating room after completion of left ITA to left anterior descending artery (LAD) and IEA to marginal or diagonal branch anastomoses. Follow-up evaluation was performed at 3 and 12 months postoperatively. RESULTS: After completion of surgery, blood flow in ITA and IEA as measured downstream from the Y anastomosis was 45+/-7 and 39+/-6 ml/min respectively. Temporary occlusion of either branch did not significantly affect flow in the other side of the arterial Y. All patients were discharged from the hospital in excellent condition. At follow-up no cases of angina recurrence were recorded. CONCLUSIONS: Composite ITA-IEA arterial grafts provide excellent short-term clinical results. Blood flow on either side is not affected by run off in the other side branch. Information from this study may be used to understand the role that undivided ITA side branches play in reducing flow rate in an ITA graft harvested during minimally invasive CABG procedures.     

Doppler echography in the intraoperative assessment of the liver circulation: an experimental study in swine

In this experimental study the authors report an experience in the evaluation of hepatic blood flow with intraoperative echo-Doppler during orthotopic liver transplantation and side-to-side or end-to-side portacaval shunt. Doppler ultrasonography studied the flow of portal vein, hepatic artery and inferior vena cava before the recipient hepatectomy, and after reperfusion during liver grafting. Furthermore echo-Doppler of the portal system was performed to confirm portacaval shunt efficacy. Usually intraoperative Doppler ultrasonography may give informations about the patency of the shunt and regarding the development of early hepatic artery thrombosis during liver transplantation, but often unclear is the exact evaluation of the velocity of the blood flow through the liver. Further experimental studies and clinical evaluations need to find safe parameters and markers of vascular alteration using this superior diagnostic procedure.