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Biomedical subjects

J Camps

Publications and source records attributed to J Camps.

At least 55 records · Page 3Linked to original sources
PubMed1997

Low versus high pressure for in vitro determination of hydraulic conductance of human dentine.

The purpose of this study was to evaluate the effect of applied pressure and measurement time on the in vitro measurement of hydraulic conductance of human dentine. Dentine slices were prepared from 50 third molars. Water was forced through the slices under a constant hydrostatic pressure. Five pressures were tested: 1.3 kPa (n = 10), 13.3 kPa (n = 10), 26.6 kPa (n = 10), 40 kPa (n = 10) and 53.3 kPa (n = 10). The volume that went through the slices was recorded every 10 min for 3 h. The volume, the fluid flow rate and the hydraulic conductance under the five pressures were compared. The volume increased with time and pressure. The fluid flow and hydraulic conductance decreased with time under 13.3, 26.6 and 40 kPa, but remained constant under 1.3 and 53.3 kPa. Used of a low pressure (1.3 kPa) may permit water to pass through dentinal tubules without disturbing intratubular contents. Medium pressures (13.3, 26.6, 40 kPa) seemed to disturb tubule contents progressively, resulting in decreased fluid flow and therefore a decreased hydraulic conductance with time. Under these pressures, the calculated values of hydraulic conductance may be unreliable because they are time-dependent. High pressure (53.3 kPa) seemed to pack the tubule contents against intratubular resistances immediately, resulting in low fluid flows and low hydraulic conductances.

Analysis of Variance↗
PubMed1997

In vitro cytotoxicity of dental adhesive systems under simulated pulpal pressure.

OBJECTIVES: Most of the devices used to evaluate the cytotoxicity of resin-based composites in vitro use a dentin barrier test. However, it is difficult to obtain the number of freshly extracted teeth, all on the same day, that is necessary for powerful statistical analysis. Tooth cryopreservation provides a way to build up a supply of teeth. This in vitro study compared cryopreserved teeth and freshly extracted teeth in an evaluation of the cytotoxicity of resin-based composites. In addition, this study also evaluated the effects of pulsatile pressure and the importance of dentin permeability on the cytotoxic response to bonding resins. METHODS: Forty freshly extracted and forty cryopreserved third molars were used. A standardized Class I cavity was prepared within the dentin. The hydraulic conductance of each tooth was recorded. The cavities were filled either with Scotchbond Multi-Purpose Plus and Z 100 (3M Dental Products) or with Optibond and Herculite (Kerr). A plexiglas device was designed to permit 24 h long contact between culture medium and the roof of the pulp chamber while a pulsatile pulpal pressure was simulated. The viability of L 929 cells cultured with a control medium and evaluated by an MTT assay was compared to that of L 929 cells cultured with medium which remained for 24 h in contact with the pulp chamber of restored teeth. A three-way ANOVA was used to compare the cytotoxicity among the different groups. A simple least-squares linear regression was used to seek a relationship between the hydraulic conductance of dentin and the cytotoxicity of composite restorative materials. RESULTS: No significant differences in cytotoxicity were found between the freshly extracted teeth and the cryopreserved teeth (p = 0.53). The cytotoxicity of the resin adhesives was statistically higher when a pulsatile pulpal pressure was simulated (p = 0.04). A significant relationship was found between the hydraulic conductance of dentin and the cytotoxicity of resin-based composites (p = 0.02). SIGNIFICANCE: Cryopreserved teeth can be used for in vitro evaluation of the cytotoxicity of resin adhesives. Pulsatile pulpal pressure simulations increased the in vitro cytotoxicity of the tested materials.

Adult↗
PubMed1997

Influence of human tooth cryopreservation on dentin bond strength.

OBJECTIVES: The goal of this study was to evaluate the effects of cryopreservation of teeth on dentin bond strength as a function of remaining dentin thickness. METHODS: Flat occlusal surfaces of human dentin were prepared in 54 freshly extracted teeth and 54 thawed, cryopreserved teeth. In each group, 18 bonds were performed in superficial dentin, 18 in mid-coronal, and 18 in deep dentin. A resin composite cylinder, 3 mm in diameter and in height, was bonded orthogonally to the surface. After storage in distilled water at room temperature for 1 wk, the bonded cylinders underwent shear testing at a crosshead speed of 0.5 mm min-1. The mean remaining dentin thickness was calculated after longitudinally sectioning the debonded samples through the center of the bonded area. Non-parametric statistical analyses were used to correlate the shear bond strength with the remaining dentin thickness among the storage modes and within the different dentin regions. RESULTS: The lowest shear bond strength values were found in the deep dentin of both fresh and cryopreserved dentin, while the values in deep and mid-coronal dentin were not significantly different in fresh and cryopreserved dentin. In the superficial and mid-coronal dentin of cryopreserved samples, the shear bond strength values were identical. There was a significant difference between the shear bond strength values in the superficial dentin of fresh teeth compared to the values for cryopreserved teeth. SIGNIFICANCE: According to the experimental conditions, tooth cryopreservation shows some promise as a substitute for freshly extracted teeth, provided that the experiments are performed in midcoronal and deep dentin.

Composite Resins↗
PubMed1997

Lipoprotein alterations in liver cirrhosis: a possible contribution to changes in plasma oncotic pressure and viscosity.

BACKGROUND/AIMS: To investigate whether physicochemical alterations in plasma lipoproteins are associated with changes in plasma oncotic pressure and viscosity in liver cirrhosis. METHODS: The study included 66 patients with cirrhosis (confirmed by liver biopsy) and 58 healthy volunteers. The constituents measured were: the concentration, density and composition of plasma lipoproteins; plasma oncotic pressure and viscosity; and the concentrations of albumin, total protein, haptoglobin, transferrin, immunoglobulin M and alpha2-macroglobulin. RESULTS: Step-wise multiple regression analysis indicated that, in the patients with cirrhosis, plasma oncotic pressure was significantly correlated with plasma albumin+viscosity (r=+0.85; p<0.001) and with plasma total protein+the density of low density lipoprotein (r=+0.74; p<0.001). The inclusion of viscosity and the density of low density lipoprotein in the regression equations significantly improved the observed correlation between albumin and plasma oncotic pressure (r=+0.70; p<0.001). Similarly, plasma viscosity was significantly correlated with the sum of plasma total protein and cholesterol (r=+0.68; p<0.001). The inclusion of cholesterol in the regression equation significantly increased the observed correlation between total protein and plasma viscosity (r=+0.59; p<0.001). CONCLUSIONS: These results suggest that lipoprotein alterations associated with liver cirrhosis may play a role in determining plasma oncotic pressure and viscosity, and thus could influence the progression of the disease.

Adult↗
PubMed1997

Plasma protein abnormalities in nephrotic syndrome: effect on plasma colloid osmotic pressure and viscosity.

The concentrations of 25 plasma proteins were measured in 22 patients with membranous nephropathy. For some large proteins, the plasma concentrations were increased; there were also large proteins with low plasma concentrations, but small or medium-sized proteins showed uniformly lower plasma concentration than the controls. Plasma colloid osmotic pressure (pi) and viscosity (eta) were not interrelated but showed positive and significant correlations with plasma concentrations of small and medium-sized proteins (pi) and plasma concentrations of large proteins (eta), respectively. Nephrotic plasma is not efficient in maintaining plasma pi but highly efficient in maintaining plasma eta. High plasma fibrinogen concentrations and low antithrombin III concentrations may predispose to thrombosis, and low IgG concentrations may account for the higher predisposition to bacterial infection. The relative composition of nephrotic plasma is heavily dependent on the size of the different proteins. Plasma pi and eta are also maintained by the relative preponderance of different plasma proteins.

Adult↗
PubMed1996

The influence of hypoalbuminemia in the generation of nephrotic hyperlipidemia.

Lipoprotein measurements in a group of 29 patients with massive proteinuria and without hypoalbuminemia, were compared with those observed in matched controls and patients with overt nephrotic syndrome to assess the influence of plasma albumin concentration and proteinuria in modulating blood lipid levels. Plasma apoprotein B and apo B containing lipoproteins were not increased in proteinuric normoalbuminemic patients. There was a good correlation between plasma albumin and oncotic pressure (r = 0.937; P < 0.001). Plasma oncotic pressure was inversely correlated with plasma apoprotein B in nephrotic patients (r = -0.44, P = 0.017) but not in normoalbuminemics (r = 0.17, P = 0.369), suggesting that plasma albumin affects apoprotein B secretion. Other findings, however, indicate that multiple processes are ocurring simultaneously in these patients. There was an accumulation of very low- and intermediate density lipoproteins in normoalbuminemics, suggesting a residual defect in the lipoprotein removal. Also, raised (P < 0.05) lipoprotein(a) levels respect to controls (median, 0.15 g/l) were noted in both, normoalbuminemics (median, 0.72 g/l) and hypoalbuminemics (median, 0.84 g/l) with similar degree of proteinuria (6.4 vs. 6.6 g/24 h), suggesting that other mechanisms may be operative in lipoprotein(a) derangements. Our findings suggest that there is no unique mechanism in the pathogenesis of nephrotic hyperlipidemia but that both hypoalbuminemia and proteinuria can have a distinct contribution, individually or in combination.

Adolescent↗
PubMed1996

Transmission of hepatitis C virus by a cardiac surgeon.

BACKGROUND: In the course of a study conducted in 1992 through 1994 of the efficacy of screening blood donors for antibodies to hepatitis C virus (HCV), we found that two patients had acquired hepatitis C after cardiac surgery, with the transmission apparently unrelated to blood transfusions. Because their surgeon had chronic hepatitis C, we sought to determine whether he was transmitting the virus to his patients. METHODS: Of 222 of the surgeon's patients who participated in studies of post-transfusion hepatitis between 1988 and 1994, 6 contracted postoperative hepatitis C, despite the use of only seronegative blood for transfusions. All six patients had undergone valve-replacement surgery. Analyses were performed to compare nucleotide sequences encompassing the hypervariable region at the junction between the coding regions for envelope glycoproteins E1 and E2 in the surgeon, the patients, and 10 controls infected with the same HCV genotype. RESULTS: The surgeon and five of the six patients with hepatitis C unrelated to transfusion were infected with HCV genotype 3; the sixth patient had genotype 1 and was considered to have been infected from another source. Thirteen other patients of the surgeon had transfusion-associated hepatitis C and were also infected with genotype 1. The average net genetic distance between the sequences from the five patients with HCV genotype 3 and those from the surgeon was 2.1 percent (range, 1.1 to 2.5 percent; P < 0.001), as compared with an average distance of 7.6 percent (range, 6.1 to 8.3 percent) between the sequences from the patients and those from the controls. The results of phylogenetic-tree analysis indicated a common epidemiologic origin of the viruses from the surgeon and the five patients. CONCLUSIONS: Our findings provide evidence that a cardiac surgeon with chronic hepatitis C may have transmitted HCV to five of his patients during open-heart surgery.

Adult↗
PubMed1996

Influence of criteria on the results of in vitro evaluation of microleakage.

OBJECTIVES: The aim of this study was to compare and explain the statistical methods employed to evaluate the in vitro sealing efficiency of adhesive restorative systems. METHODS: Two hundred and sixty sound freshly extracted human premolars were randomly divided into 13 groups. Standardized cavities were prepared, and the teeth were restored with 13 restorative systems. The teeth were thermocycled, immersed in dye, embedded in resin and sectioned. Five evaluation criteria were recorded: mean, median and mode of the data measured on each tooth, maximum dye penetration measurements on each tooth, and percentage of teeth in each group without any dye penetration. For each parameter, one-way ANOVAs and Duncan a posteriori tests were used to compare the 13 systems. RESULTS: The number of non-statistically different subgroups, pointed out by Duncan tests, was greater when the selected criterion was the maximum dye penetration (6 subgroups) or the percentage of teeth without any penetration (5 subgroups) than when the criterion was the median (3 subgroups), the mode or the mean (4 subgroups). The positioning of the 13 adhesive restorative systems established from the five criteria was different. Equivalent adhesion strategies revealing different experimental results indicate that other factors contribute to the final effectiveness of a particular system: clinical approach with respect to the formation of an elastic bonding layer, and shrinkage, physical and rheological properties of resin composite. SIGNIFICANCE: The results of these in vitro studies of dye penetration must be considered as comparisons and not as absolute conclusions. The maximum dye penetration measured on each tooth, which complies with the aim of the in vitro evaluation of sealing efficiency defined by Pashley (1990) and allows powerful statistical analysis of results, seems to be the best evaluation criterion.

Analysis of Variance↗
PubMed1996

Influence of tooth cryopreservation and storage time on microleakage.

OBJECTIVES: This study was conducted to compare microleakage of two new dentin bonding agents on freshly extracted teeth, cryopreserved teeth, or teeth stored in water containing 0.5% chloramine at 4 degrees C. METHODS: Rectangular Class V cavity preparations were made on the buccal and the lingual surface of wisdom teeth. They were filled with either Scotchbond Multi-Purpose and Z100 (3M Dental Products) or with Gluma 2000 and Pekafill (Bayer Dental). After thermocycling, silver staining penetration was evaluated under a light microscope. SEM examination and EDX analysis were performed to evaluate the microleakage pattern. The results were analyzed by the use of a two-way analysis of variance. RESULTS: Cryopreservation for 13 wk or 12 d refrigeration did not produce changes in the amount of microleakage. However, 48 d or longer of refrigeration increased microleakage. There was no correlation between changes in microleakage and storage time. Specimens prepared with both dentin bonding agents exhibited the same microleakage values and the same microleakage pattern. SIGNIFICANCE: Refrigeration at 4 degrees C in 0.5% chloramine for 48 d or longer may cause an increase in microleakage. Cryopreservation for 13 wk or short-term refrigeration did not affect the microleakage.

Analysis of Variance↗
PubMed1996

Effects of S-adenosylmethionine on lipid peroxidation and liver fibrogenesis in carbon tetrachloride-induced cirrhosis.

BACKGROUND/AIM: The aim of this study was to investigate the effects of S-adenosylmethionine on liver peroxidation and liver fibrogenesis in carbon tetrachloride-induced cirrhosis. METHODS: Cirrhosis was induced in three groups of six rats by repeated injections of carbon tetrachloride over 9 weeks. One group of animals was treated only with carbon tetrachloride, and the other two received carbon tetrachloride plus S-adenosylmethionine (10 mg/kg intramuscularly daily) from week 3 to week 9, and from week 6 to week 9 of the study, respectively. Two additional groups of six rats, a control group and a group treated only with S-adenosylmethionine, were also studied. Glutathione concentration, thiobarbituric acid-reactive substances, collagen content, prolyl hydroxylase activity, and procollagen type I mRNA expression were determined in liver samples. RESULTS: All carbon tetrachloride-treated rats had cirrhosis at the end of the study. Cirrhosis was also present in five of the six carbon tetrachloride-treated rats receiving S-adenosylmethionine for 3 weeks, but in only one of the six rats that received S-adenosylmethionine for 6 weeks. Hepatic glutathione was significantly diminished in carbon tetrachloride-treated rats (2.7 +/- 0.3 mumol/g tissue) and returned to normal in rats receiving S-adenosylmethionine for 3 or 6 weeks (3.7 +/- 0.13 and 3.9 +/- 0.11 mumol/g tissue, respectively). The hepatic thiobarbituric acid-reactive substances were significantly lower in rats treated with carbon tetrachloride and S-adenosylmethionine for 6 weeks (98 +/- 5 nmol/g) than in rats treated with carbon tetrachloride (134 +/- 12 nmol/g) and in those treated with carbon tetrachloride and S-adenosylmethionine for 3 weeks (127 +/- 13 nmol/g). There were no differences in either hepatic collagen and prolyl hydroxylase activity between rats that received only carbon tetrachloride and those treated with S-adenosylmethionine for 3 weeks. In contrast, carbon tetrachloride-treated rats receiving S-adenosylmethionine for 6 weeks had significantly lower collagen and prolyl hydroxylase activity than the other two groups. A much greater increase in procollagen type I mRNA was found in carbon tetrachloride-treated rats than in rats treated with carbon tetrachloride and S-adenosylmethionine for 6 weeks. Furthermore, there was a significant correlation between the hepatic thiobarbituric acid-reactive substances and prolyl hydroxylase activity and hepatic collagen. CONCLUSIONS: We conclude that the early administration of S-adenosylmethionine in a model of carbon tetrachloride-induced liver injury restores glutathione levels and reduces lipid peroxidation, resulting in less advanced liver fibrosis.

Animals↗
PubMed1996

Fungal endocarditis in premature infants: case report and review.

Fungal endocarditis in premature infants has rarely been reported; only 16 cases have been described. We present a fatal case of endocarditis due to Candida albicans in a patient requiring neonatal intensive care and parenteral nutrition via a central venous catheter; there were no preexisting pathological abnormalities. The patient had sepsis with multisystem organ failure, resulting in death. A postmortem examination was performed, and the most important findings are presented. The literature on fungal endocarditis in premature infants is reviewed as well.

Antifungal Agents↗
PubMed1995

An alternative technique for treatment of choledocholithiasis found at laparoscopic cholecystectomy.

OBJECTIVE: To introduce a new strategy for dealing with abnormal cholangiograms at laparoscopic cholecystectomy that makes postoperative cholangiograms possible and facilitates stone extraction by assuring access to the duct for a guide-wire-assisted endoscopic retrograde sphincterotomy. DESIGN: Retrospective review of a prospectively maintained database. PATIENTS: Twenty-four patients with abnormal cholangiograms had a percutaneously placed double-lumen catheter threaded through the cystic duct and advanced into the duodenum. RESULTS: Ten successful guide-wire-assisted endoscopic retrograde sphincterotomies were performed without complications. Eleven normal postoperative cholangiograms suggested spontaneous stone passage or false-positive intraoperative cholangiograms. There were three technical failures in the early part of the series. CONCLUSIONS: This strategy is a reasonable alternative to laparoscopic common bile duct exploration (1) when the cholangiogram is questionably positive, (2) when prolonged anesthesia (poor-risk patient) should be avoided, (3) when the equipment for laparoscopic common bile duct exploration is not available, and (4) when spontaneous stone passage seems likely. Postoperative endoscopic retrograde sphincterotomy with stone extraction is facilitated when it becomes necessary because a guide wire can be introduced through the catheter.

Adult↗
PubMed1995

Influence of concentration and application time of maleic acid on dentin permeability.

OBJECTIVES: Since dentin permeability ultimately affects bond strength, the purpose of this study was to compare the effects of different concentrations of maleic acid, and different exposure times on dentin permeability. METHODS: One hundred and thirty freshly extracted human non-carious third molars were used. Hydraulic conductance was determined after various treatments. The teeth were divided into five groups. In the first group, the smear layer was untreated. In three other groups, 0.10, 0.25, or 0.5 M aqueous solution of maleic acid was applied on dentin slices for 15, 30, or 60 s. In the last group, the Scotchbond Multi-Purpose dental adhesive system (3M Dental Products) conditioner was applied for 15, 30, or 60 s. RESULTS: After a 60 s exposure time, the Scotchbond Multi-Purpose dentin conditioner or the 0.1 M solution of maleic acid was as effective at increasing dentin permeability as the 0.25 M and 0.5 M maleic acid solutions. The maximum dentin permeability was reached after 15 s with 0.25 M and 0.5 M solutions of maleic acid, after 30 s with Scotchbond Multi-Purpose and after 60 s with the 0.1 M solution of maleic acid. During the first 30 s, the 0.1 M solution of malic acid did not increase dentin permeability and did not completely remove the smear layer; a SEM examination of the dentin slices corroborated the functional results. SIGNIFICANCE: The manufacturer's recommendation of 15 s of etching using Scotchbond Multi-Purpose conditioning gel produced a moderate amount of etching which increases dentin permeability to about one-half its maximum value.

Acid Etching, Dental↗
PubMed1995

Influence of low dose allopurinol on ischaemia--reperfusion injury during abdominal aortic surgery.

OBJECTIVES: To ascertain whether surgery causes ischaemia-reperfusion (I-R) related injury, if this injury is augmented by preoperative shock, and reduced with low dose allopurinol. DESIGN: Randomised blind placebo controlled trial. SETTING: Surgical laboratory. MATERIAL AND METHODS: 22 pigs were randomly allocated to four groups; OP = operation/placebo, OA = operation/ allopurinol, SOP = shock + operation/placebo, SOA = shock + operation/allopurinol. An aortic tube prosthesis was inserted in all. In groups SOP and SOA preoperative shock was induced by exsanguination. Allopurinol was administered in group OA on the preoperative day and peroperatively, in group SOA during shock and peroperatively. CHIEF OUTCOME MEASURES: Perioperative blood concentrations of thiobarbituric acid reactive species (TBARS), ascorbic acid (AA), albumin, 99mTc-albumin and creatine phosphokinase (CPK) as indicators of oxidative membrane damage, antioxidant activity, microvascular permeability changes and muscular cell damage respectively. MAIN RESULTS: In the OP and OA groups TBARS gradually increased, while AA, 99mTc-albumin and CPK remained unchanged and albumin decreased. No effect of allopurinol was observed in these groups. In the SOP group TBARS and AA were not significantly different from groups OP and OA. Yet, albumin, 99mTc-albumin and CPK decreased significantly more in the SOP group. Compared with the SOP group, allopurinol treatment (SOA) produced lower TBARS and higher AA levels, and reduced the effect of shock on albumin, 99mTc-albumin and CPK concentrations. CONCLUSIONS: Aortic surgery causes no I-R related damage. Pre-operative shock produces I-R related damage, which is reduced by allopurinol.

Allopurinol↗