[Successful treatment of an aortoduodenal fistula after operation on the abdominal portion of the aorta]

Gastrointestinal haemorrhage is a common cause of emergency admission of patients to surgical hospitals. Within the structure of nosological entities, not unreasonably referred to the rarest causes of gastrointestinal bleeding is the formation of an aortointestinal fistula whose early diagnosis is of paramount importance. The clinical picture may be different but it is mostly represented by gastrointestinal haemorrhage. The incidence of gastrointestinal fistulas following a surgical intervention ranges from 0.6 to 2.3%. Unless timely diagnosed and with incorrect therapeutic decision-making, the mortality rate amounts to 90%. In this article we present a clinical case report regarding successful treatment of a patient presenting with a secondary aortoduodenal fistula occurring 5 years after previously performed aortofemoral bypass grafting and complicated by relapsing intestinal bleeding and acute ischaemia of the right lower extremity.

[AUTOVENOUS REVASCULARIZATION OF THE LOWER EXTREMITY ARTERIES IN PATIENTS WITH VARIANT ANATOMY OF THE PERIPHERAL BLOOD FLOW AND THE PROGRESSIVE ATHEROSCLEROTIC PROCESS]

Obliterating diseases of the lower extremity arteries occupy a high proportion in the structure of cardiovascular morbidity in the population among the developed countries. The steadily progressing course of obliterating atherosclerosis leads to the critical lower limb ischemia and causes an unfavorable prognosis for preserving the extremity, as well as the patient's life. Nowadays, there are two ways of surgical management of this pathology: endovascular and open reconstructive interventions. The choice of the method is based on a comprehensive keeping of the patient-specific records, including the anatomical characterization of the arterial bed lesions. In case of extended occlusion of the superficial femoral artery, the open reconstructive surgery using a large saphenous vein as a transplant is recommended. This circumstance is confirmed by the autovein patency in the long term compared with a synthetic prosthesis according to the results of randomized clinical trials. Therefore, with the formation of a distal anastomosis below the gap of the knee joint, the patency of the autovein and synthetic prosthesis after 5 years is 71% and 44% respectively. In this article, we represent a clinical case of successful treatment of a patient with progression of atherosclerotic lesions of the infrainguinal segment arteries. A staged revascularization of the femoral-popliteal segment arteries using technique of a reversed vein on both lower extremities after attempts of the conservative treatment and x-ray endovascular intervention was performed. A feature of this case is the creation of a new bifurcation of the popliteal artery during the formation of a distal anastomosis below the fissure of the knee joint under the contitions of a high discharge of the anterior tibial artery.The given clinical case demonstrates the advantages of invasive surgical tactics with the aim of preserving the limb and improving the patient's quality of life.

Correlation between intraluminal oxygen gradient and radial partitioning of intestinal microbiota

BACKGROUND & AIMS

The gut microbiota is a complex and densely populated community in a dynamic environment determined by host physiology. We investigated how intestinal oxygen levels affect the composition of the fecal and mucosally adherent microbiota.

METHODS

We used the phosphorescence quenching method and a specially designed intraluminal oxygen probe to dynamically quantify gut luminal oxygen levels in mice. 16S ribosomal RNA gene sequencing was used to characterize the microbiota in intestines of mice exposed to hyperbaric oxygen, human rectal biopsy and mucosal swab samples, and paired human stool samples.

RESULTS

Average Po2 values in the lumen of the cecum were extremely low (<1 mm Hg). In altering oxygenation of mouse intestines, we observed that oxygen diffused from intestinal tissue and established a radial gradient that extended from the tissue interface into the lumen. Increasing tissue oxygenation with hyperbaric oxygen altered the composition of the gut microbiota in mice. In human beings, 16S ribosomal RNA gene analyses showed an increased proportion of oxygen-tolerant organisms of the Proteobacteria and Actinobacteria phyla associated with rectal mucosa, compared with feces. A consortium of asaccharolytic bacteria of the Firmicute and Bacteroidetes phyla, which primarily metabolize peptones and amino acids, was associated primarily with mucus. This could be owing to the presence of proteinaceous substrates provided by mucus and the shedding of the intestinal epithelium.

CONCLUSIONS

In an analysis of intestinal microbiota of mice and human beings, we observed a radial gradient of microbes linked to the distribution of oxygen and nutrients provided by host tissue.

Quantitative assessment of brain microvascular and tissue oxygenation during cardiac arrest and resuscitation in pigs

Cardiac arrest is associated with a very high rate of mortality, in part due to inadequate tissue perfusion during attempts at resuscitation. Parameters such as mean arterial pressure and end-tidal carbon dioxide may not accurately reflect adequacy of tissue perfusion during cardiac resuscitation. We hypothesised that quantitative measurements of tissue oxygen tension would more accurately reflect adequacy of tissue perfusion during experimental cardiac arrest. Using oxygen-dependent quenching of phosphorescence, we made measurements of oxygen in the microcirculation and in the interstitial space of the brain and muscle in a porcine model of ventricular fibrillation and cardiopulmonary resuscitation. Measurements were performed at baseline, during untreated ventricular fibrillation, during resuscitation and after return of spontaneous circulation. After achieving stable baseline brain tissue oxygen tension, as measured using an Oxyphor G4-based phosphorescent microsensor, ventricular fibrillation resulted in an immediate reduction in all measured parameters. During cardiopulmonary resuscitation, brain oxygen tension remained unchanged. After the return of spontaneous circulation, all measured parameters including brain oxygen tension recovered to baseline levels. Muscle tissue oxygen tension followed a similar trend as the brain, but with slower response times. We conclude that measurements of brain tissue oxygen tension, which more accurately reflect adequacy of tissue perfusion during cardiac arrest and resuscitation, may contribute to the development of new strategies to optimise perfusion during cardiac resuscitation and improve patient outcomes after cardiac arrest.

Reverse saturable Absorption in Organically Doped Xerogels

Pd and Zn - tetraphenyltetrabenzoporphyrins (PdTPTBP and ZnTPTBP), hexacyanin 3 (HITCI), and substituted phthalocyanines were incorporated in solid-state matrices (xerogels) using a sol-gel process. Nonlinear reverse saturable absorption was observed with those materials when they were illuminated with nanosecond laser pulses at 532 nm, or other wavelengths in the visible spectrum (between 450 nm and 630 nm). PdTPTBP doped xerogels exhibit a nonlinear activation threshold of about 10 mJ/cm , which is much lower than the value of 80 mJ/cm2 obtained under similar conditions with classical Al phthalocyanine chloride, or HITCI molecules. Solid state “red active” reverse saturable absorbers can be obtained with substituted phthalocyanines doped xerogels. The different experimental results are discussed using classical 4- energy level diagrams.

In vitro effects of photodynamic therapy on Aspergillus fumigatus

Photodynamic therapy is a technique for killing cells with visible light after pretreatment with a photosensitizing agent. We demonstrated significant in vitro fungicidal activity against Aspergillus fumigatus of the photosensitizer Green 2W, activated with 630 nm light. This effect was both inoculum- and light dose-dependent. At a Green 2W concentration of 31.5 mg/L, there was complete killing of 2.7 x 10(1) cfu/mL with a light dose of 110 J/cm(2) and up to 2.7 x 10(6) cfu/mL with a light dose of 385 J/cm(2).

Electrostatic core shielding in dendritic polyglutamic porphyrins

Polyglutamic dendritic porphyrins of the general formula H2PophGlu(N)OR (H2Porph = free-base meso-tetra-4-carboxyphenylporphyrin (H2TCPP), Glu=dendrimer layer composed of L-glutamates, N= 1-3: dendrimer generation number, R = terminal group (All, H)) were synthesized and characterized with NMR and MALDI-TOF mass spectroscopy. The free-acid terminated compounds were found to be highly soluble in water, with both their absorption and fluorescence spectra dependent on pH. The value of the porphyrin mono-protonation constant, measured by fluorescence rationing, increased monotonously in the studied series of dendrimers (pK3=6.31. 6.70, and 6.98, for N=1, 2, 3, respectively). For the largest dendrimer, H2PorphGlu(3)OH, pK3 was found shifted by almost two pH units relative to the non-modified H2Porph. The second protonation constant (K4) was much less affected by the dendritic substituents. At pH values less than 3.5 there were noticeable changes in fluorescence intensity and quantum yield even for the highly soluble H2PorphGlu(3)OH. This suggests that interactions between individual dendritic molecules in solution are favored by full protonation of the peripheral glutamic carboxyls. The "dendrimer-protected" porphyrins are convenient fluorescent pH sensors in the biological pH range.

Oxygen distributions within R3230Ac tumors growing in dorsal flap window chambers in rats

R3230Ac mammary tumors were grown in transparent window chambers implanted into the dorsal skin flap of 250 g Fischer 344 rats (see Dewhirst et al, 1992). The oxygen pressure distributions in the tumor and host tissue were measured by the oxygen dependent quenching of phosphorescence (see Vinogradov et al, 1996) after injection of Oxyphor R2 (7 mg, 0.3 ml) into the tail vein. The oxygen pressure maps show the R3230Ac tumors to be hypoxic relative to the surrounding tissue. The excitation spectrum for the phosphor has peaks at 419 nm (blue light) and at 524 nm (green light), and the emitted phosphorescence spectrum and lifetime are independent of the wavelength at which the phosphor is excited. The absorption by tissue is much greater for blue light than green light, due to intrinsic chromophores such as cytochromes, hemoglobin, myoglobin etc. Thus, blue excitation measures the oxygen pressures in a much thinner, superficial, surface layer (< 50 microns) than does green excitation, allowing "optical sectioning" of tissue oxygenation. The tissue can be further optically sectioned by making measurements from both sides of the window. Viewed from the tumor side, the superficial layers (blue excitation) of these tumors were hypoxic whereas the host tissue was well oxygenated. The oxygen pressures in the growing edge of the tumors are lower than those in the central core of the tumor, and much lower than those of the host tissue. This result is in agreement with the micro-oxygen electrode measurements of perivascular oxygen pressures reported by Dewhirst and coworkers (1992).

Oxygen distribution in the vasculature of mouse tissue in vivo measured using a near infra red phosphor

Oxygen dependent quenching of phosphorescence has been used to measure the oxygenation of tissue in mice, including the differences between normal tissue and that of a murine tumor. Approximately 0.3 mg of the phosphorescence oxygen probe, Green 2W, was injected into the tail vein of tumor bearing mice. The mice were immobilized using an anesthetic cocktail and illuminated with flashes (< 4 microseconds t1/2) of light of 636 +/- 15 nm. The emitted phosphorescence (790 nm max.) was measured using an imaging phosphorimeter with an intensified CCD camera, an instrument which provides two dimensional digital maps of oxygen pressure. Both the illumination light and the phosphorescence were in the near infra red region of the spectrum, where skin and tissue have little absorption. The light can therefore readily pass through the skin and centimeter thickness of tissue. Mice are sufficiently small that the oxygen pressure maps could be obtained by illuminating from either the same or the opposite side as the camera (and tumor). The tumors were observed as regions with oxygen pressures substantially below those of the surrounding normal tissue. Thus, it is possible to non-invasively detect these tumors and to monitor their internal oxygen pressure in real time and through cm of tissue.

Extended porphyrins. New IR phosphors for oxygen measurements

Tetrabenzoporphyrins (TBP) of Zn, Pd, Lu, Y, Sn and Pb show strong absorption bands in the near IR region of the spectrum. Phosphorescence in dimethylformamide (DMF) solutions at room temperature was measured for Pd and Lu complexes giving quantum yields of 7.9% and 3.5% and lifetimes of 250 microseconds and 870 microseconds, respectively. Pd meso-tetraphenyltetrabenzoporphyrin 1 (PdPh4TBP) shows a red shift of the absorption Q-band to 628 nm. 1 reacted with ClSO3H and obtained chlorosulfonato derivative 2 was converted to a set of water soluble chromophores: Pd meso-tetra(sulfophenyl)tetrabenzoporphyrin (Pd Ph4(SO3Na)4TBP) 3, corresponding sulfonamide (Pd Ph4(PEG)4TBP) 4 with aminopolyethyleneglycol (Av.M.W. 5,000) and sulfonamide derivatives of glucoseamine (Pd Ph4(glucoseamine)4TBP) 5 and aminophenylacetic acid (Pd Ph4(phenac)4TBP) 6. Electronic absorption and phosphorescence spectra of 1 and some of its derivatives were recorded and phosphorescence quantum yields and lifetimes were measured for deoxygenated solutions. The oxygen quenching constants were measured for the water soluble complexes 3 and 4 and found to be suitable for oxygen measurements in vivo. Tetranaphthaloporphyrin (TNP) complexes of Pd and Lu as well as Pd meso-tetraphenyltetranaphthaloporphyrin (PdPh4TNP) were synthesized and their absorption and emission properties were examined.

Noninvasive imaging of the distribution in oxygen in tissue in vivo using near-infrared phosphors

A newly developed water-soluble phosphor suitable for measuring oxygen pressure in the blood (Green 2W) was used for noninvasive, in vivo imaging of oxygen distribution in the vascular systems of mice. Oxygen quenches the phosphorescence of Green 2W, measured in the presence of 2% albumin, according to the Stern-volmer relationship. This oxygen-dependent quenching of phosphorescence has been used to obtain digital maps of the oxygen distribution in the tissue vasculature. EMT-6 mammary carcinoma tumors were grown by injecting 1 x 10(6) cells in 0.1-ml carrier into the subcutaneous space over the muscle on the hindquarter. When the tumors were approximately 8 mm in diameter, 300 micrograms of phosphorescence probe (Green 2W; absorption maximum 636 nm) was injected into the tail vein. The mice were immobilized with intraperotoneal Ketamine (133 mg/kg) and Xylazine (10 mg/kg) and illuminated with flashes (< 4-microseconds t1/2) of light of 630 +/- 12 nm. The emitted phosphorescence (790-nm maximum) was imaged an intensified CCD camera. Images were collected beginning at 30, 50, 80, 120, 180, 240, 420, and 2500 microseconds after the flash and used to calculate digital maps of the phosphorescence lifetimes and oxygen pressure. Both the illumination light and the phosphorescence were in the near-infrared region of the spectrum, where tissue has greatly decreased absorbance. The light therefore readily passed through the skin and centimeter thicknesses of tissue. The oxygen maps could be obtained by illuminating from the side of the mouse opposite the camera (and tumor). The tumors were readily observed as regions with oxygen pressures substantially below those of the surrounding tissue. Thus, phosphorescence measurements can noninvasively detect volumes of tissue with below-normal oxygen pressure in the presence of much larger volumes of tissue with normal oxygen pressures. In addition, tissue oxygen pressures can be monitored in real time, even through centimeter thicknesses of tissue.

Phosphorescence lifetime analysis with a quadratic programming algorithm for determining quencher distributions in heterogeneous systems

A new method for analysis of phosphorescence lifetime distributions in heterogeneous systems has been developed. This method is based on decomposition of the data vector to a linearly independent set of exponentials and uses quadratic programming principles for x2 minimization. Solution of the resulting algorithm requires a finite number of calculations (it is not iterative) and is computationally fast and robust. The algorithm has been tested on various simulated decays and for analysis of phosphorescence measurements of experimental systems with descrete distributions of lifetimes. Critical analysis of the effect of signal-to-noise on the resolving capability of the algorithm is presented. This technique is recommended for resolution of the distributions of quencher concentration in heterogeneous samples, of which oxygen distributions in tissue is an important example. Phosphors of practical importance for biological oxygen measurements: Pd-meso-tetra (4-carboxyphenyl) porphyrin (PdTCPP) and Pd-meso-porphyrin (PdMP) have been used to provide experimental test of the algorithm.

[Changes in vessels of the microcirculatory bed following parenteral administration of xenogeneic cerebrospinal fluid obtained in vivo to normal animals and animals with experimental hypercholesterolemia]

Effect of parenteral administration of xenogenic liquor, vitally obtained, on the state of the microcirculatory bed, as well as its biostimulating action for cellular metabolism activation have been studied. The number of actively functioning capillaries increases, microvessels dilate, vascular permeability intensifies not only under normal conditions, but under experimental hypercholesteremia, as well. How the changes observed in the microcirculatory bed depend on various doses and total amount of the preparation administered, as well as means of its conservation have been analysed and stated. The dynamics of indices on lipid metabolism have been studied.