Drainage of subretinal fluid during scleral buckling surgery for rhegmatogenous retinal detachment.

BACKGROUND AND OBJECTIVE: The purpose of the study is to compare the drainage of subretinal fluid (SRF) in a scleral pocket (SP) with incision parallel to the limbus to drainage through a simple radial scleral thinning (ST), during scleral buckling surgery for rhegmatogenous retinal detachment (RRD). PATIENTS AND METHODS: Retrospective cohort study of one hundred sixty-nine consecutive buckling surgery for RRD, where a drainage puncture was performed through SP in eighty-five cases and through previous radial ST in eighty-four cases. RESULTS: PT shows significant lower complication rate. The incidence of retinal incarceration or formation of a retinal hole at the first drainage site is lower in PT group (p=0.0285). During surgery choroidal detachment have been observed in a higher percentage of cases in the SP group (p=0.0379). At the end of the surgery a certain amount of SRF behind the buckling was significant in ST group (p=0.0026). CONCLUSION: The SP drainage technique appears to be a useful, effective and safe method to drain SRF.

How to set up a microsurgical laboratory on small animal models: organization, techniques, and impact on residency training.

Microsurgical training is mandatory for the optimal education of modern neurosurgeons. Even though this is a widely acknowledged statement and a lot of institutions around the world practice training in laboratory, the recent literature lacks tip and tricks on how to start a laboratory from scratch, what would be a convenient anesthesia, and what kind of exercises are appropriate. We present our experience in 16 microsurgical training courses settled up at our institutions. Two hundred eleven rodents were dissected. We will describe the organization of the laboratory and of the training courses and we will discuss its practical impact on the residency program.

Hepatic microcirculation and cholangiocyte physiopathology.

BACKGROUND: The peribiliary plexus (PBP) plays a fundamental role in supporting the functions of the biliary epithelium. After common bile duct ligation (BDL) progressive PBP proliferation is demonstrated. We have, recently, demonstrated that the biliary epithelium express Vascular Endothelial Growth Factor (VEGF), both subtype -A and -B and VEGF receptors. Taking in consideration the wide extension of PBP during BDL, aim of our study is to investigate the role of VEGF in stimulating angiogenesis and also in the modulation of epithelial cells proliferation. MATERIAL AND METHODS: Experimental studies were performed by evaluating the effects of: a) endogenous VEGF neutralization by chronic administration of anti VEGF-C antibody on cholangiocyte proliferation in BDL rats and; b) the hepatic artery ligation (HAL) immediately after BDL followed by treatment (7 days) with a recombinant of VEGF-A (administered through IP implanted minipumps) on cholangiocyte proliferative activities. RESULTS: Both administration of antiVEGF-C antibody and HAL decreases cholangiocyte proliferation. The decrease of cholangiocyte proliferation was associated with depressed VEGF-A protein expression. The administration of rVEGF-A to BDL, hepatic artery ligated rats prevented the decrease of cholangiocyte proliferation and VEGF-A expression as compared to BDL control rats. CONCLUSION: These data suggest that VEGF-C modulates the proliferative activities of cholangiocytes in experimental cholestasis and that circulating factors (i.e., VEGF) in the blood supply of the intra-hepatic biliary epithelium, play an important role in the balance between cholangiocyte proliferation/loss.

Microvascular features and ossification process in the femoral head of growing rats.

In the epiphysis of long bones, different patterns of development of ossification processes have been described in different species. The development of the vascularisation of the femoral head has not yet been fully clarified, although its role in the ossification process is obvious. Our aim was to investigate ossification and vascular proliferation and their relationship, in growing rat femoral heads. Male Wistar rats aged approximately 1, 5 and 8 wk and 4, 8 and 12 mo were used. Light microscopy frontal sections and vascular corrosion casts observed by scanning electron microscopy were employed. In the rat proximal femoral epiphysis, ossification develops from the medullary circulation of the diaphysis, quickly extending to the neck and the base of the head. Hypertrophic chondrocytes occupy the epiphyseal cartilage, and a physeal plate with regular cell columns is present. Starting from about the end of the third month one or more points of fibrovascular outgrowth, above the physeal line, can be observed in each sample. They are often placed centrally or, sometimes, peripherally. The fibrovascular outgrowths penetrate deeply into the cartilage and extend laterally. At age 8 mo, large fibro-osseous peduncles connect the epiphysis to the diaphyseal tissue. At 12 mo, the entire epiphysis appears calcified with an almost total absence of residual cartilage islands. This situation differs in man and in other mammals due both to differing thickness of the cartilage and to the presence of more extensive sources of blood vessels other than the diaphyseal microcirculation, as supplied by the teres ligament and Hunter's circle. In young rats, subchondral vessels and the synovial fluid could play a role in feeding the ossifying cartilage. Later, a loss of resistance of the physis due to marked degeneration of the cell columns, and extensive chondrocyte hypertrophy permit fibrovascular penetration starting from diaphyseal vessels rather than neighbouring vascular territories, such as those of the periosteum and capsule.

SEM corrosion-casts study of the microcirculation of the flat bones in the rat.

BACKGROUND: Little is known about the organization of microcirculation in flat bones in comparison with long bones. This study, therefore, helps us to determine the design of this vascular system in flat bones in relation to their structure and function. METHODS: The organization of microvasculature in parietal, scapula, and ileum bones of 15 young sexually mature rats, aged 6-7 weeks, was studied by light and scanning electron microscopy (SEM) from vascular corrosion cast (vcc), a resin-cast obtained material. RESULTS: Our observations show that the pattern of the microcirculation in flat bones is different in the thick and thin parts of such bones. Where the bone is thinner than 0.4 mm, only periosteal and dural network exist. Larger vessels which do not form a real network connect the two tables of the bones in these regions. In thicker areas, the organization of the microvasculature is similar to that in long bones, with distinct periosteal, cortical and bone marrow networks. Moreover, in different bones, outer networks show slightly different characteristics according to the different adjacent structures (dura mater, muscles etc.). Different types of vessels were recognized by comparing their different diameter, course and endothelial imprints. CONCLUSIONS: The microvascular patterns of the flat bones are strongly influenced by the bone thickness. The different microvascular systems can interact both with the bone modelling and remodeling and with the variable metabolic needs, modifying the microvascular pattern and the blood flow. This is even more important in view of the reciprocal influence of the different networks within the same bone.

Felodipine protects human atrial muscle from hypoxia-reoxygenation dysfunction: a force-frequency relationship study in an in vitro model of stunning.

AIMS: We aimed at investigating contractile changes after hypoxia-reoxygenation and dobutamine challenge in superfused human atrial pectinate muscle to see whether high versus low stimulation rate during hypoxia might account for outcome differences compatible with the definition of an in vitro model of myocardial stunning and whether pretreatment with the dihydropyridine Ca2+ entry blocker felodipine might afford protection. METHODS: Human right atrial trabeculae obtained from adult patients were superfused in an organ bath with oxygenated (O2 content 16 ml/l) and modified (NaHCO3 25.7 mmol/l) Tyrode's solution at 37 degrees C. Dobutamine (1 nmol/l to 10 micromol/l) was superfused in 10 oxygenated preparations to select the optimal drug concentration to be used in another 22 which were randomized. Group (A) consisted of time-related controls (Tyrodes's solution for 225 min at cycle length (CL) 1600 ms and no dobutamine). There were two test groups, respectively: (B) low (1600 ms CL) and (C) high (400 ms CL) stimulation rate. After 60 min of stabilization, in groups B and C, hypoxic superfusion (O2 content 5 ml/l) lasted 60 min, then reoxygenation (60 min) and dobutamine challenge (1 micromol/l, 15 min) were performed. Analysis of variance for repeated measures with the Greenhouse-Geisser correction, and a repeated measures model with structured covariance (preparation mass, length, width and time-varying time to peak tension) matrices were used whereby grouping (G), time (T) and G x T interaction were weighted. Force-frequency relationship and post-pausal potentiation were studied after each phase. Electrophysiology, histomorphometry and electron microscopy were carried out (n=6). Felodipine (0.1 micromol/l, n=5) pretreatment (15 min before hypoxia) was given in parallel experiments. RESULTS: Time-related controls showed approximately 10% per hour decrease of developed tension and the Paradise test provided approximately 80% of control values. In test groups (as compared to baseline values) contractility was decreased approximately 65% after hypoxia-reoxygenation and it increased approximately 25% after dobutamine (G, 0.0065

Hepatic microcirculation and peribiliary plexus in experimental biliary cirrhosis: a morphological study.

BACKGROUND & AIMS: The peribiliary plexus plays a fundamental role in supporting the secretory and absorptive functions of biliary epithelium. Little information is available on the rearrangement of the peribiliary plexus during conditions associated with ductular proliferation. This study investigated the chronological modulation of bile duct and peribiliary plexus proliferation after common bile duct ligation in the rat. METHODS: Light microscopy and scanning electron microscopy vascular corrosion cast technique was used to study the architecture of the peribiliary plexus in rats with 1, 2, and 4 weeks of common bile duct ligation or in sham-operated controls. RESULTS: After 1 week of common bile duct ligation, no evident change of hepatic microvasculature was observed despite significant proliferation of bile ducts. After 2 and 4 weeks, significant microvasculature proliferation was observed extending from the peribiliary plexus of bile tracts. Vascular proliferation coincides with the extension of portal tract connective tissue. No evidence of vascular proliferation or other morphological modifications was present at the level of sinusoids around the portal tracts. CONCLUSIONS: After common bile duct ligation, the peribillary plexus undergoes marked proliferation, thus supporting the increased nutritional and functional demands from the proliferated bile ductal system. However, the proliferation of the peribillary plexus only occurs after that of the bile ductal system.

Precapillary patterns and perivascular cells in the retinal microvasculature. A scanning electron microscope study.

The microvasculature of the rat retina was studied in male Wistar rats in order to examine the features of the precapillary vascular pattern and structure that could affect blood flow regulation. Vascular corrosion casts and partially digested tissue specimens were observed by scanning electron microscopy. Side branching rather than bifurcation was the predominant microvascular pattern in the arterial tree. Two types of precapillary arteriole were present, one with the characteristic pattern of a preferential channel; the other gave off capillaries as terminal branches. At the origin of arteriolar side branches, smooth muscle cells appeared to buckle the endothelial nuclei into the vascular lumen. It is concluded that the rat retinal microvasculature appears to be characterised by 2 distinctive features: (1) side branching of arterioles which allows preferential flow in the most superficial layers of the retina; (2) peculiar luminal restrictions of arterioles and capillaries which permit fine regulation of blood flow.

A morphological study on femoral heads in human hip joint osteoarthrosis.

Several pathogenetical and clinical interpretation of osteoarthritic modifications are given in the literature. In this work we tried to compare in humans macroscopic, structural and ultrastructural observations on eight osteoarthritic with four femural heads from control patients. The sample for Light Microscopy and Scanning Electron Microscopy observations came from selected regions of the femural head, which included both cartilage and bone tissue of loaded and unloaded regions. The cartilage showed superficial lesions, such as erosions and fissures, and deep lesions that included matrix alterations and chondrocyte proliferation. In relation to the thickening of the subchondral bone we noticed an irregular bone-cartilage surface with signs of bone tissue proliferation. The trabeculae appeared thickened in loaded zones and rarefied in unloaded ones. Cavities were sometimes present at different depths in cancellous bone. Our observations allow us to conclude that cartilage lesions are precocious, diffusely located and relatively independent of the considered zone of the femural head, while bone tissue alterations seem evenly sited and chronologically subsequent. The cavities in the cancellous bone could produce load modifications and consequent bone deformity.

Ibopamine in glaucoma diagnostics: a new pharmacological provocative test.

PURPOSE: Ibopamine is used when performing provocative tests, thanks to its pharmacological property of increasing ocular pressure in eyes with outflow system impairment. This study summarizes the latest results that we have achieved with reference to its clinical-diagnostic use. METHODS: 175 (250 eyes) POAG patients, 101 (190 eyes) glaucoma suspects with mild ocular hypertension, 39 (64 eyes) NTG patients and 163 (326 eyes) healthy volunteers underwent an ibopamine provocative test. Among the POAG and the glaucoma suspects, 49 (92 eyes) and 20 (38 eyes) patients were selected who, starting from the performing of ibopamine test, had at least one year of perimetric follow-up. These patients have been assessed for the perimetric defect progression in relation to the (negative or positive) response to ibopamine. RESULTS: the ibopamine test was positive for 92% of the glaucomatous patients, 61% of the glaucoma suspects, 52% of the NTG patients and 0% of the healthy volunteers. It was observed that 28% of the ibopamine-positive glaucoma suspects showed a perimetric deterioration during an average 2.5-year follow-up. No perimetric deterioration was found on ibopamine-negative glaucoma suspects (Fisher's exact test: p = 0.038). Among glaucomatous patients, 46% of the test-positive individuals showed a progressive trend of the perimetric defect, as against about 8% of glaucomatous test-negative patients (Fisher's exact test: p = 0.003). CONCLUSIONS: We believe that the ibopamine provocative test can be usefully applied especially to epidemiological screening studies to identify patients who might develop ocular hypertension or glaucoma and in the follow-up of glaucoma suspects, to identify individuals who have a greater risk of developing perimetric defects.

Topical ibopamine and corticosteroids in the treatment of post-surgery ocular hypotony.

PURPOSE: The aim of the present preliminary study, performed on post-surgical hypotony, was the evaluation of the effects on ocular hypotony of the concomitant administration of ibopamine and corticosteroids. METHODS: 14 patients (11 males-3 females; mean age 47 years) with ocular hypotony following several vitroretinal surgical intervention in different districts, were enrolled. The inclusion criteria were: mean IOP during tonometric curve equal or lower than 6 mmHg, stable IOP for at least 60 days, ongoing treatment with 0.1% dexamethasone (4 times/day), successful surgical intervention, 2% ibopamine (4 times/day) was added to the corticosteroid therapy for 30-60 days. RESULTS: Before ibopamine administration, mean IOP was 4.07 mmHg SD 1.71. At the end of the treatment period, mean IOP increased by 89% in comparison to baseline values (+ 3.64 mmHg SD 5.57). This difference was statistically significant (paired t = 2.39; P = 0.03). One month after ibopamine-treatment discontinuation, mean IOP decreased to pre-treatment values (4.86 mmHg SD 3.50). CONCLUSIONS: The results of the present study, although preliminary, suggest the possibility of a future pharmacological treatment of ocular hypotony with ibopamine, whose rationale is based on the increase of aqueous humor production by stimulating the D1 dopaminergic receptor.

Hepatic microcirculation as a morpho-functional basis for the metabolic zonation in normal and pathological rat liver.

The hepatic microcirculation is well known as a fundamental component of the liver structure, deeply involved in the zonal organization of the acinar structure. In cirrhosis, the microvascular tree shows dramatic changes that would heavily influence the development of the disease. When the cirrhosis becomes evident the result is a progressive organ failure, also in presence of only moderately decreased hepatocyte volume. The aim of this research was to compare the role of microcirculation of the hepatic zonation in normal and cirrhotic livers. Cirrhosis was experimentally induced in 36 rats following a controlled intragastric CCl4 administration. Cirrhotic and control normal livers were processed for routine light microscopy, histoenzimology, and scanning electron microscopy vascular corrosion cast. Control livers showed normal hepatic structure and microvascularization; enzymatic activities were constantly and normally distributed. In CCl4-treated animals LM showed a characteristic micronodular cirrhosis in all livers. Vascular corrosion casts under the scanning electron microscope displayed a progressive reduction of the distance between pre- and post-sinusoidal vessels and the presence of newly formed perinodular plexus. The histoenzymatic analysis demonstrated the loss of zonation in the cirrhotic parenchyma. Moreover, the sinusoid/hepatocyte ratio was significantly reduced, because of the presence of two or more hepatocyte thick laminae during the scarring development. The altered microcirculation in cirrhosis also changed the normal acinous metabolic gradient. The histoenzymatic study revealed a zonal rearrangement of the cirrhotic liver metabolic activity, that leads to a progressive hepatic failure. These data confirm the fundamental importance of the normal relationship between the hepatocyte laminae and the sinusoids for the preservation of a normal zonation which represents the basis for a normal liver function.

Scanning electron microscopy of collagen fiber orientation in the bone lamellar system in non-decalcified human samples.

Previous studies on collagen fiber orientation have led to different interpretations and theories about the fiber arrangement in the lamellar compact bone. The purpose of this investigation was to provide new and more in-depth data on fiber arrangement in the lamellar bone system in order to explain the orientation of the fiber bundles. This was carried out by applying a simple method of preparation which permitted observation of non-decalcified samples. A previously isolated Haversian system was subjected to slow bending up to reaching the fracture point. Hence, the fracture surface was observed by SEM. The same samples were also observed by polarized light microscopy. A significant alternation of fiber orientation in the adjacent lamellae was observed. Different domains of differently oriented fibers were present within the same lamella; conjugating fibers connecting adjacent lamellae were also shown. This method avoided most of the artifacts due to chemical treatment of bone samples. The results can be easily interpreted by means of the same criteria applied in mechanics for the studying of composite materials.

Zinc supplementation in experimental liver cirrhosis: a morphological, structural and ultrastructural study.

Zinc treatment in liver cirrhosis is known to prevent a number of clinical symptoms. Previous studies have also indicated that Zn has a protective effect on the development of the clinical, biochemical and morphological manifestations of hepatic injury if administered simultaneously with the noxious agent. In this study, the protective effects of zinc treatment against the development of liver cirrhosis have been tested in cirrhotic rats treated by intragastric administration of CCl4. The development of morphological lesions has been investigated by means of standardized and comparable techniques, LM, TEM, SEM, microvascular casts and measurements of liver collagen content by colorimetric determination in paraffin embedded sections. LM and EM observations showed typical morphological features of cirrhosis in all CCl4 treated rats. In the same group of animals, the microvascular casts showed the development of the typical 'perinodular' branching and the various anastomoses of pre and post-sinusoidal vessels. Colorimetric evaluation has shown a significant increase in collagen content after CCl4 treatment. Qualitative and quantitative data of livers of CCl4 treated rats supplemented or not with zinc were significantly similar. In conclusion, zinc treatment influences biochemical parameters, but not the morphology of liver cirrhosis.

A scanning electron microscopic study of liver microcirculation disarrangement in experimental rat cirrhosis.

Hepatic microcirculation has been related to liver function in several studies. The principle of this relationship lies in the sequential distribution of blood from the feeding vessels of the hepatic acinus to the central vein. This study was undertaken to investigate the progressive changes at different sites of the liver microvascular bed in the developing cirrhosis, both by light microscopy and scanning electron microscopy of corrosion casts. Experimental cirrhosis was induced with intragastric carbon tetrachloride. The most important vascular changes progressively observed are the reduction of the distance between the pre- and postsinusoidal vessels, the presence of newly formed shunting vessels bypassing the sinusoids and, finally, the development of a perinodular vascular plexus composed of pre- and postsinusoidal vessels. Newly formed vessels grow through preformed tissue septa. These vascular modifications make any zonal gradient hardly possible. The loss of the zonal gradient of perfusion could highly modify liver function, along with the structural changes of hepatic laminae. Hepatocyte regeneration cannot recover the original vascular relationships: this makes the morphological and functional destructuralization of cirrhotic liver irreversible.

Microcirculation of the extrahepatic biliary tree: a scanning electron microscopy study of corrosion casts.

The microvascular arrangement of the extrahepatic biliary tree of the rat was studied by light microscopy (LM) and scanning electron microscopy (SEM) of vascular corrosion casts. The plexus that encircles the lumen of the common bile duct, observed by LM, showed a network of vessels of different diameter situated under the epithelium in the lamina propria. Parallel SEM observations of the same structure demonstrated the presence of 2 main vascular layers: an outer arterial and venous layer, corresponding to the larger vessels seen by LM, and a richer inner capillary layer just under the epithelium. On the luminal part of the corrosion casts, there were many round avascular empty pits that corresponded to the presence of small acinar glands distributed along the epithelium of the common bile duct. The rich subepithelial capillary network present in the rat, an animal without a gallbladder, may play an important role in the reabsorption of water and solutes from bile. Moreover, in pathological conditions (e.g. portal hypertension), liver blood flow may take a preferential collateral route through the intrahepatic peribiliary plexus into the relatively large diameter vessels of the extrahepatic peribiliary plexus because of the continuity of the 2 plexi.

Electrophysiologic monitoring of diabetic retinopathy in pregnancy.

The authors studied the correlations between electroretinographic, ophthalmologic, and clinical parameters in 30 pregnant women (20 with diabetes and 10 control subjects). Diabetic patients were divided into two groups: group 1 included 11 cases of insulin-dependent diabetes (IDDM); and group 2 included 6 cases of noninsulin-dependent diabetes (NIDDM) and 3 cases of gestational diabetes (GDM). Adapto-electroretinography (AERG) was used as the main monitoring parameter, and in particular, the relationship between the cone-mediated (b1) and rod-mediated (b2) components of the b wave (b2/b1 ratio) 7 minutes after photobleaching was studied. The results indicate that the b2/b1 ratio can detect functional modifications before the onset of ophthalmoscopically detectable retinopathy. Significant statistical correlations were demonstrated both between the type of diabetes and AERG responses, and between metabolic control (HbA1c values) and AERG alterations. A higher maternofetal complication rate in those patients with severe and frequent AERG alterations during pregnancy also was found.

The hepatic microcirculation in experimental cirrhosis. A scanning electron microscopy study of microcorrosion casts.

The experimental model of liver cirrhosis induced by intragastric administration of CCl4 reproduces not only the histological picture of the postnecrotic cirrhosis but also its pathophysiological features. Corrosion casts of livers affected by CCl4-induced cirrhosis show the loss of the lobular pattern. Once the cirrhosis has completely developed, the whole microvascular bed appears to be composed of groups of sinusoid nodules of diameters varying between 0.3 and 1.5 mm.. Pre- and post-sinusoidal vessels and anastomoses between the former and the latter are mainly located at the perinodular spaces. This microvascular situation modifies the normal perfusion gradient within the parenchyma. Nevertheless, it can allow a still viable function.

Retinal microcirculation as revealed by SEM corrosion casts in the rat.

The morphology of the retinal microcirculation has been extensively studied by different techniques. Nevertheless, some problems concerning the capillary bed lamination and pre- and postcapillary patterns have not yet been clarified. In the present study the SEM corrosion cast technique was employed to study the three-dimensional relationships of rat retinal vessels and to follow the smallest vascular branches. Rat retina is considered a useful experimental model for a number of pathologies which affect the microvascular bed deeply. Two precapillary patterns have been observed. Precapillary arterioles gave rise to capillaries both as terminal branches or as collaterals. The former pattern of ramification allows only a regulation of flow in a whole group of capillaries downstream, the latter pattern could provide a finer regulation of blood flow. SEM corrosion casts have shown very well the lamination of the capillary bed: one can easily realize this by seeing the overlapped meshes of the two different planes, vessels in between the two capillary laminae can always be followed from one meshwork to the other. This three-dimensional organization is an interesting model for retinal circulation because it shows many features in common with the retina of humans and primates.

Microcirculation of the extra-ocular muscles of rats. A scanning electron-microscopic corrosion cast study.

Specific researches, employing corrosion casts, were performed on different skeletal muscles, but not on extra-ocular muscles (EOMs). The microvascular bed of EOMs was studied by the corrosion cast technique in the rat. Two histologically and physiologically different layers were present in the EOMs. On the whole, the capillary pattern of EOMs was less dense than in the other skeletal muscles. The EOM orbital layer turned out to have a higher number of transverse anastomoses and tuning-fork divisions than the global layer had. These different microcirculatory patterns can be related with the physiological function and the anatomical situation of the EOMs.