Zirconia Surface Treatments for Resin Bonding.

PURPOSE: To evaluate the bond strength of resin to zirconia treated with different surface conditioning methods. MATERIALS AND METHODS: Sintered zirconia was surface treated to create 7 groups. Ceramic liner (L) was fired onto three groups of zirconia and subsequently received the following treatments: hydrofluoric acid etching (L/ HFE), alumina particle abrasion (L/APA), and alumina particle abrasion with hydrofluoric acid etching (L/APAHFE). All three groups were silane treated immediately prior to bonding. Two other zirconia groups received alumina particle abrasion with and without silane coupling (AP-S and AP). Another group underwent selective infiltration etching, in which the specimens received porcelain powder firing, ultrasonic etching with HF for 15 min, then rinsing under running water for 15 min, followed by silane treatment (SIE). The control group was zirconia as-sintered (ZAS). Twenty composite resin cylinders were luted to each group with a resin cement. Each group was divided into two subgroups (n=10) and subjected to 2 storage conditions: 24 h water storage or 21 days with 6000 thermocycles between 5°C and 55°C. Shear bond strength testing (SBS) was performed, followed by statistical analysis of the results using one-way ANOVA (p < 0.05). RESULTS: After 21 days of thermocycling, AP and ZAS groups spontaneously debonded prior to testing. The remaining groups showed a decrease in mean shear bond strength between 11.7% and 58.5% after thermocycling, except the L/HFE group, which increased by 11.7%. L/HFE showed the highest bond strength at both test intervals, and at 21 days was significantly higher than that of the AP-S and L/APA-HFE groups, which in turn were higher than that of the L/APA group, which was higher than that of the SIE group (p < 0.05). CONCLUSION: The etched, fired ceramic liner with silane treatment provided the strongest and most durable bond under the conditions tested. Alumina particle abrasion degraded the durability of the ceramic liner. Alumina particle abrasion, as-sintered zirconia, and SIE did not provide durable bond strengths.

A barbourin-albumin fusion protein that is slowly cleared in vivo retains the ability to inhibit platelet aggregation in vitro.

Barbourin is a 73 amino acid venom protein that inhibits platelet aggregation. Recombinant barbourin (BARH6), rabbit serum albumin (RSAH6), and a barbourin-RSA fusion protein (barbourin-linker-albumin; BLAH6) were secreted from Pichia pastoris yeast, and purified by nickel-chelate affinity chromatography via their C-terminal hexahistidine (H6) tags. BARH6 and BLAH6 did not differ in their IC50s for inhibition of platelet aggregation using either human platelets stimulated with thrombin or ADP, or rabbit platelets stimulated with ADP. BARH6 and BLAH6 were also effective in inhibiting platelet aggregation in whole blood, and formed complexes with platelet integrin alphaIIbbeta3. The terminal catabolic half-life of BLAH6 approached that of RSAH6 [3.4 +/- 0.2 versus 4.0 +/- 0.1 days (n = 4 +/- SD)], but was substantially increased relative to that of BARH6 [0.15 +/- 0.03 days (n = 3 +/- SD)]. Our results suggest that fusion to albumin slows the clearance of barbourin in vivo, while preserving its ability to inhibit platelet aggregation.

Duplex assessment of run-off before femorocrural reconstruction.

BACKGROUND: This study was a prospective evaluation of colour duplex imaging for the assessment of distal run-off before femorocrural reconstruction. METHODS: Patients with critical ischaemia who required a distal bypass underwent preoperative run-off assessments using dependent Doppler, arteriography and duplex imaging by a vascular surgeon, radiologist and technologist respectively; each was blinded to the findings of the others. Preoperative data were compared with intraoperative clinical findings and completion flow studies/ arteriograms. RESULTS: Forty-three consecutive patients (33 men, ten women; mean age 78 (range 53-95) years; 12 diabetic) undergoing 44 femorocrural reconstructions for critical ischaemia were assessed. The 30-day primary cumulative graft patency for the series was 86 per cent. Dependent Doppler correctly predicted a suitable run-off vessel in 21 limbs but was indeterminate in four and unrecordable in 19. Arteriography correctly predicted a suitable run-off vessel in 32 cases, but was indeterminate in six and failed to demonstrate run-off in three patients. Arteriography suggested an inferior vessel in three cases. Duplex correctly predicted a suitable run-off vessel for all 44 grafts. CONCLUSION: Duplex imaging is superior to arteriography for preoperative assessment of distal run-off for femorocrural reconstruction.

Acute gastrointestinal hemorrhage detected by selective scintigraphic angiography.

Intra-arterial 99mTc colloid scintigraphy may have greater sensitivity than either standard intravenous scintigraphy or selective arteriography in detecting gastrointestinal bleeding. Ten millicuries of 99mTc colloid were administered directly into the superior and inferior mesenteric arteries (SMA and IMA) of patients who had undergone selective arterial catheterization for the evaluation of gastrointestinal bleeding. In one patient, 99mTc-albumin colloid was administered directly into the IMA and identified diverticular bleeding. The bleeding had been occult to prior contrast arteriography and refractory to selective intra-arterial Pitressin therapy. In a second patient who had undergone three negative provocative angiograms, selective SMA injection of 99mTc-sulfur colloid identified occult mesenteric varices secondary to portal hypertension. Selective intra-arterial scintigraphy should be valuable in detecting intestinal bleeding occult to conventional studies. This will help in directing further therapy and diagnostic evaluation.

Plasma levels of human neurotensin: methodological and physiological considerations.

The ingestion of a meal high in fat content is known to increase circulating levels of neurotensin (NT) in humans. However, the magnitude of the postprandial rise of NT in the general circulation and its physiological significance have been subject of much debate. The present study examines circulating levels of NT in male volunteers prior to and following each of their three daily meals (ca. 31 g fat/meal). The response observed are also compared to that elicited by the direct instillation of intralipid (ca. 44 g fat) into the duodenum. NT levels were determined by radioimmunoassay of acid/acetone extracted plasma fractionated by high pressure liquid chromatography. Meals caused a significant but modest increase in NT levels, with the largest increment (ca. 4 fmol/ml) occurring after breakfast. In contrast, NT levels increased ca. 20 fmol/ml with intraduodenal instillation of lipid. The meal-stimulated increases in circulating NT measured here are 4- to 5-fold less than those reported by others, the difference most likely reflecting the lesser amount of lipid ingested. Previous studies provided subjects with single meals containing in excess of 120 g of fat; the 30 g of fat ingested by our subjects, ca. 33% of total caloric intake, is near that recommended by the U.S. Senate, Select Committee on Nutritional and Human Needs. These data show that diets with a reasonable fat content have only a modest effect on circulating levels of NT.

Biliary complications of gallstone lithotripsy detected by Tc-99m DISIDA scintigraphy.

Extracorporeal shock wave lithotripsy (ESWL) has been reported to be a safe and relatively effective non-invasive treatment for radiolucent gallbladder calculi in selected patients. Ideally, the goal of successful treatment is the passage of all fragments from the gallbladder into the intestinal tract. Biliary colic has been reported in up to 35% of treated patients, although complications such as cholecystitis, cholangitis, common bile duct obstruction, and pancreatitis are surprisingly infrequent. Cholescintigraphy is the procedure of choice in patients with biliary colic and suspected acute cholecystitis. It has proven to be more sensitive than ultrasound in detecting acute common bile duct (CBD) obstruction, since functional obstruction precedes morphologic dilatation of the CBD. This report reviews two cases of post-lithotripsy cystic and common duct obstruction and discusses the role of Tc-DISIDA scintigraphy following gallstone ESWL.

Microglial mitogens are produced in the developing and injured mammalian brain.

The central nervous system produces growth factors that stimulate proliferation of ameboid microglia during embryogenesis and after traumatic injury. Two microglial mitogens (MMs) are recovered from the brain of newborn rat. MM1 has an approximate molecular mass of 50 kD and a pI of approximately 6.8; MM2 has a molecular mass of 22 kD and a pI of approximately 5.2. These trypsin-sensitive proteins show specificity of action upon glia in vitro serving as growth factors for ameboid microglia but not astroglia or oligodendroglia. Although the MMs did not stimulate proliferation of blood monocytes or resident peritoneal macrophage, MM1 shows granulocyte macrophage colony-stimulating activity when tested upon bone marrow progenitor cells. Microglial mitogens may help to control brain mononuclear phagocytes in vivo. The MMs first appear in the cerebral cortex of rat during early development with peak levels around embryonic day E-20, a period of microglial proliferation. Microglial mitogens are also produced by traumatized brain of adult rats within 2 d after injury. When infused into the cerebral cortex, MM1 and MM2 elicit large numbers of mononuclear phagocytes at the site of injection. In vitro study shows that astroglia from newborn brain secrete MM2. These observations point to the existence of a regulatory system whereby secretion of proteins from brain glia helps to control neighboring inflammatory responses.

The role of mononuclear phagocytes in wound healing after traumatic injury to adult mammalian brain.

We monitor cellular responses to a penetrating wound in the cerebral cortex of adult rat during the first weeks after injury. Two classes of activated mononuclear phagocytes containing acetylated low-density lipoprotein (ac-LDL) receptors appear within hours at the wound site. One type of cell surrounding the lesion edge had thin, delicate processes and is identical in appearance to ramified microglia found in developing brain. Within the lesion, round cells are recognized as blood-borne macrophages when labeled by intravenous injection of carbon particles. Thus, both process-bearing reactive microglia and invading macrophages respond to brain trauma. The greatest number of ac-LDL(+) or nonspecific esterase(+) mononuclear phagocytes appears 2 days after injury within the wound site and are associated with a peak production of the cytokine interleukin-1 (IL-1). Because intracerebral infusion of IL-1 is known to stimulate astrogliosis and neovascularization (Giulian et al., 1988), we examine the time course of injury-induced reactive astrogliosis and angiogenesis. A 5-fold increase in the number of reactive astroglia is found at 3 d and a marked neovascularization at 5 d after injury. During the first week, mononuclear phagocytes engulf particles and clear them from the wound site either by migrating to the brain surface or by entering newly formed brain vasculature. To investigate further the role of reactive brain mononuclear phagocytes in CNS injury, we use drugs to inhibit trauma-induced inflammation. When applied in vivo, chloroquine or colchicine reduce the number of mononuclear phagocytes in damaged brain, help to block reactive astrogliosis and neovascularization, and slow the rate of debris clearance from sites of traumatic injury. In contrast, the glucocorticoid dexamethasone neither reduces the number of brain inflammatory cells nor hampers such responses as phagocytosis, astrogliosis, neovascularization, or debris clearance in vivo. Our observations show that mononuclear phagocytes play a major role in wound healing after CNS trauma with some events controlled by secretion of cytokines. Moreover, certain classes of immunosuppressive drugs may be useful in the treatment of acute brain injury.

Neurotensin levels in the hepatic-portal circulation are inversely related to the circadian feeding cycle in rats.

To investigate whether the circulating level of neurotensin (NT) in the rat is related to either the 24-h pattern in food consumption or environmental lighting conditions, the plasma level of NT was determined every 4 h in the hepatic-portal vein and the abdominal aorta over the course of 24 h. At each time interval, pooled plasma samples from groups of 4 rats were extracted, lyophilized, reconstituted, and subjected to HPLC. Column fractions were radioimmunoassayed with both N- and C-terminal directed antisera. Animals housed in a 12-h light, 12-h dark cycle and given food and water ad libitum had a significant (P less than 0.05) 24-h variation in the level of chromatographically and immunochemically identified NT in the portal circulation while the level of NT in the systemic circulation remained unchanged. The level of NT in portal blood ranged from 12-38 fmol/ml and was highest in the afternoon, 12-16 h after peak feeding. The level of NT in aortic blood never exceeded 7 fmol/ml. Similar results were obtained from animals exposed to constant illumination for 13-32 h with free access to food and water. The release of NT during the fasting phase of the feeding cycle was dependent upon the prior intake of food, since the level of NT in the hepatic-portal circulation of rats housed in 12-h light, 12-h dark cycle and fasted for 20-24 h was about 2-fold less than that observed in animals allowed free access to food. In summary, these data show that the release and circulation of NT are tightly linked to the circadian pattern of food intake and that the greatest release of NT into the hepatic-portal circulation occurs 5-10 h after the cessation of eating during the fasting phase of the feeding cycle.

Circadian rhythm of neurotensin levels in rat small intestine.

The present studies were undertaken to determine whether a 24 h rhythm occurs in neurotensin (NT) levels in the small intestine of the rat and if so, whether the rhythm depends upon the 24 h cycles of light or feeding. A total of 145 male rats were sacrificed at 4 h intervals and the levels of neurotensin-like immunoreactivity (NTLI) in the middle 30 cm of small intestine were determined by radioimmunoassay with region specific antisera. There was a significant (P less than 0.05) 24 h rhythm in the levels of NTLI in groups of rats maintained under constant illumination or a 12:12 light:dark cycle and fasted for either 24 h or provided food ad libitum. Levels of NTLI ranged from 50 to 140 pm/g and were highest during the early morning (0400-0800 h) and lowest during the afternoon (1200-1600 h). The NTLI from samples taken at 0400 and 1600 h was subjected to high-performance liquid chromatography. The levels of chromatographically and immunochemically characterized NT were consistent with the levels of NTLI, evidence that the 24 h variation in NTLI most likely reflects changes in the intestinal content of NT and not other substances with similar immunochemical properties.

Alcohol and fatty acid stimulation of neurotensin release from rat small intestine.

We have previously reported that neurotensin (NT) is released from the small intestine and elevated in the hepatic-portal circulation in response to the perfusion of the small intestine with a micellar solution of oleic acid. In order to determine the minimum acyl chain length and whether the presence of a carboxylic acid is necessary for the stimulation of NT release, the small intestine of anesthetized rats was perfused with test solutions of fatty acids of 2-, 4-, 8-, or 18-carbons or fatty alcohols of 2-, 4-, or 8-carbons at a concentration of 1 mM prepared in 2.4 mM taurodeoxycholate in 0.9% NaCl. Blood samples, collected from the superior mesenteric vein immediately before the start of the test perfusion and at 15-min intervals thereafter, were extracted immediately and radioimmunoassayed for NT-like immunoreactivity (NTLI) with a C-terminal-directed antiserum. Perfusions of fatty acids with 4 or more carbons and alcohols of 2 or more carbons resulted in a significant elevation (P less than 0.05) in plasma levels of NTLI above the values obtained before the onset of perfusion. Perfusions with ethanol resulted in a value of 4.3 +/- 0.03 mg/dl (SEM) in blood from the superior mesenteric vein while there was no increase in ethanol levels in the peripheral circulation. Perfusion with taurodeoxycholate and 0.9% NaCl alone had no significant effect on plasma levels of the NTLI. In order to characterize the chemical nature of the elevated NTLI, plasma samples from animals perfused with test solution were collected, extracted, pooled, and subjected to HPLC. NT and its N-terminal metabolite, NT(1-8), were quantitated. NT was defined as material having the same retention time as synthetic NT standard and having comparable measurements using N- and C-terminal-directed antisera. Perfusions of fatty acids of four or more carbons and alcohols of two or more carbons resulted in a 2- to 4-fold increase of both NT and NT(1-8) levels in plasma. It is particularly interesting that perfusion with ethanol (2-carbons) causes an elevation in plasma NT, because perfusion with acetic acid (2-carbons) does not increase NTLI. The fact that perfusion of ethanol is effective in releasing intestinal NT suggests that NT may mediate some of the biological effects observed after the consumption of alcohol.