A finite element study on stress distribution of two different attachment designs under implant supported overdenture

Objective

This study aimed to evaluate stress patterns generated within implant-supported mandibular overdentures retained by two different attachment types: ball and socket and locator attachments.

Materials and methods

Commercial CAD/CAM and finite element analysis software packages were utilized to construct two 3D finite element models for the two attachment types. Unilateral masticatory compressive loads of 50, 100, and 150 N were applied vertically to the overdentures, parallel to the longitudinal axes of the implants. Loads were directed toward the central fossa in the molar region of each overdenture, that linear static analysis was carried out to find the generated stresses and deformation on each part of the studied model.

Results

According to FEA results the ball attachment neck is highly stressed in comparison to the locator one. On the other hand mucosa and cortical bone received less stresses under ball and socket attachment.

Conclusions

Locator and ball and socket attachments induce equivalent stresses on bone surrounding implants. Locator attachment performance was superior to that of the ball and socket attachment in the implants, nylon caps, and overdenture. Locator attachments are highly recommended and can increase the interval between successive maintenance sessions.     

Laparoscopy assisted transjejunal endoscopic retrograde cholangiography for treatment of intrahepatic duct stones in a post Roux-en-Y patient

We report a case of a 17-year-old female patient, who was operated on for choledocal cyst with Roux-en Y hepatojejunostomy. She was admitted to hospital with recurrent attacks of acute ascending cholangitis due to left intrahepatic duct stones. After a failed attempt at conventional endoscopic retrograde cholangiopancreatography through the anatomical route, she was treated successfully with laparoscopy assisted transjejunal endoscopic retrograde cholangiography.Endoscopic access to the biliary system can be difficult in patients with surgically altered anatomy of the upper gastrointestinal tract (GIT), such as Roux-en-Y reconstruction, because of the changed anatomy. However, endoscopic retrograde cholangiopancreatography (ERCP) is challenging in cases such as our patient;1,2 this is due to the distance needed to be traversed and looping. Our objective in presenting this particular case is to describe and highlight a laparoscopy assisted transjejunal ERCP to permit successful treatment and removal of intrahepatic duct stones in a post Roux-en-Y patient, and to minimize surgical inetervention to reduce unnecessary risks to the patient.     

Protection of murine bone marrow by dexamethasone during cytotoxic chemotherapy

Corticosteroids have the ability to suppress the production of growth factors and cytokines and are thus implicated in the negative regulation of hematopoiesis. We have shown that the corticosteroids, prednisolone and dexamethasone, were able to effectively protect progenitor cells in four strains of mice against cell-cycle-specific antimetabolic chemotherapy agents. The highest levels of protection against 5-fluorouracil (FU; 200 mg/kg) were achieved when two or three intraperitoneal injections of dexamethasone were administered between - 7 and +3 hours at a dose of 7.5 mg/kg/injection (optimal dose) or by continuous infusion between -4 and +20 hours. This protective effect is manifested as an increase in the number of high proliferative potential colony-forming cells that survive in the bone marrow 3 days after treatment with FU from between 0.5% and 11% to between 10% and 34% of normal. The bone marrow progenitors and blood cell numbers return to normal from 3 to 5 days and 1 to 2 days earlier, respectively. Less dexamethasone than prednisolone is required to give an equivalent protective effect, which is consistent with their anti-inflammatory potency. These findings are further evidence of the negative regulatory role played by corticosteroids, and indicate that the treatment schedules of corticosteroids during cancer therapy need to be reexamined to obtain the maximum benefit from their use.     

Conjugated dihydroxy bile salt inhibition of glucose influx in rat jejunumin vitro

Effects of bile salts on intestinal glucose transfer differ in diverse animal preparations exposed to various bile acids. Radiolabeled glucose influx into rat jejunum in vitro was studied in buffer and compared to taurodeoxycholate, taurochenodeoxycholate, taurocholate, and deoxycholate. Jejunum was obtained from intact, bile-diverted, and colestipoltreated rats and in similar categories after abdominal x-irradiation. Taurodeoxycholate but not taurocholate inhibited glucose influx only in bile-fistula and colestipol-treated rats. Bile diversion increased and colestipol decreased glucose uptake from buffer. Added inhibitory effects of irradiation and bile salts were seen in bile-fistula animals. These data suggest that normal exposure to bile is chronically inhibiting jejunal glucose transport and that dihydroxy bile salts are responsible for this effect. They do not provide an explanation for the role of bile in the intestinal radiation syndrome.This work was supported in part by contract No. AT-(40-1) 3882 from the U.S. Atomic Energy Commission.These data were presented in part at the annual meeting of the Southern Society for Clinical Investigation, New Orleans, La. February, 1975.     

Roscovitine synergizes with conventional chemo-therapeutic drugs to induce efficient apoptosis of human colorectal cancer cells

AIM： To examine the ability of cyclin-dependent kinase inhibitor （CDKI） roscovitine （Rosco） to enhance the antitumor effects of conventional chemotherapeutic agents acting by different mechanisms against human colorectal cancer. METHODS： Human colorectal cancer cells were treated, individually and in combination, with Rosco, taxol, 5-Fluorouracil （5-FU）, doxorubicine or vinblastine. The antiproliferative effects and the type of interaction of Rosco with tested chemotherapeutic drugs were determined. Cell cycle alterations were investigated by fluorescence-activated cell sorter FACS analysis. Apoptosis was determined by DNA fragmentation assay. RESULTS： Rosco inhibited the proliferation of tumor cells in a time-and dose-dependent manner. The efficacies of all tested chemotherapeutic drugs were markedly enhanced 3.0-8.42 × 10^3 and 130-5.28 × 10^3 fold in combination with 5 and 10 μg/mL Rosco, respectively. The combination of Rosco and chemotherapeutic drugs inhibited the growth of human colorectal cancer cells in an additive or synergistic fashion, and in a time and dose dependent manner. Rosco induced apoptosis and synergized with tested chemotherapeutic drugs to induce efficient apoptosis in human colorectal cancer cells. Sequential, inverted sequential and simultaneous treatment of cancer cells with combinations of chemotherapeutic drugs and Rosco arrested the growth of human colorectal cancer cells at various phases of the cell cycle as follows： Taxol/Rosco （G2/M-and S-phases）, 5-FU/Rosco （S-phase）, Dox/Rosco （S-phase） and Vinb/Rosco （G2/M-and S-phases）. CONCLUSION： Since the eff icacy of many anticancer drugs depends on their ability to induce apoptotic cell death, modulation of this parameter by cell cycle inhibi-tors may provide a novel chemo-preventive and chemo-therapeutic strategy for human colorectal cancer.     

Isolated Roux loop pancreaticojejunostomy versus pancreaticogastrostomy after pancreaticoduodenectomy: a prospective randomized study

Objectives

The optimal strategy for the reconstruction of the pancreas following pancreaticoduodenectomy (PD) is still debated. The aim of this study was to compare the outcomes of isolated Roux loop pancreaticojejunostomy (IRPJ) with those of pancreaticogastrostomy (PG) after PD.

Methods

Consecutive patients submitted to PD were randomized to either method of reconstruction. The primary outcome measure was the rate of postoperative pancreatic fistula (POPF). Secondary outcomes included operative time, day to resumption of oral feeding, postoperative morbidity and mortality, and exocrine and endocrine pancreatic functions.

Results

Ninety patients treated by PD were included in the study. The median total operative time was significantly longer in the IRPJ group (320 min versus 300 min; P = 0.047). Postoperative pancreatic fistula developed in nine of 45 patients in the IRPJ group and 10 of 45 patients in the PG group (P = 0.796). Seven IRPJ patients and four PG patients had POPF of type B or C (P = 0.710). Time to resumption of oral feeding was shorter in the IRPJ group (P = 0.03). Steatorrhea at 1 year was reported in nine of 42 IRPJ patients and 18 of 41 PG patients (P = 0.029). Albumin levels at 1 year were 3.6 g/dl in the IRPJ group and 3.3 g/dl in the PG group (P = 0.001).

Conclusions

Isolated Roux loop PJ was not associated with a lower rate of POPF, but was associated with a decrease in the incidence of postoperative steatorrhea. The technique allowed for early oral feeding and the maintenance of oral feeding even if POPF developed.