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Biomedical subjects

Stephen Clark

Publications and source records attributed to Stephen Clark.

8 recordsLinked to original sources
PubMed2007

Effect of tobacco smoking on advancement flap repair of complex anal fistulas.

PURPOSE: Options for the management of complex anal fistulas include fistulotomy, setons, fibrin sealant, and advancement flaps. This study was performed to evaluate our results with advancement flap repair of anal fistulas and to identify factors associated with failure. METHODS: A retrospective analysis was performed for all patients treated with an anal fistula between June 2000 and May 2003. Data collected included age, gender, fistula anatomy and etiology, previous repairs, comorbidities, smoking history, procedure performed, and fistula recurrence. RESULTS: There were 95 patients (43 males and 52 females) with a mean age of 42 years. Transsphincteric fistulas were present in 51 patients and 44 females had rectovaginal fistulas. A mucosal flap repair was performed for 68 patients and 27 patients had an anodermal flap repair. The median length of follow-up was ten months. The fistula recurred in 31 patients (32.6 percent). Subset analysis showed an association between a history of previous attempts at repair or tobacco smoking and an increased rate of fistula recurrence, but did not reveal any increased risk of recurrence for patients over age 40 years, for those with rectovaginal fistula, or for males. CONCLUSION: A history of previous attempts at repair of an anal fistula or tobacco smoking is associated with an increased risk of fistula recurrence; while age over 40 years, male gender, or a rectovaginal fistula are not.

Adult↗
PubMed2006

Fibrin glue as an adjunct to flap repair of anal fistulas: a randomized, controlled study.

PURPOSE: Both flap repair and fibrin glue are accepted sphincter-preserving techniques for managing anal fistulas. Additionally, the two techniques are not mutually exclusive and can be combined. This trial was undertaken to determine whether the combination of flap repair and fibrin glue resulted in better outcomes than flap repair alone. METHODS: Between July 2000 and March 2004, patients with trans-sphincteric anal fistulas were randomly assigned to advancement flap repair alone or flap repair combined with fibrin glue obliteration of the fistula tract. Data regarding age, gender, fistula anatomy, race, and previous repairs were collected. Fistulas managed by fistulotomy or caused by Crohn's disease, acute obstetric trauma, or radiation were excluded from this study. RESULTS: There were 58 patients randomized to flap repair alone or flap repair with fibrin glue (47 males; median age, 47 (range, 29-68) years). Mucosal advancement flap was performed in 36 patients and anodermal advancement flap was performed in 22. The median follow-up was 22 (range, 12-36) months. Total fistula recurrence rate for all patients was 32.6 percent. The recurrence rate for fistulas repaired by advancement flap alone was 20 percent, whereas the recurrence rate for fistulas repaired by advancement flap with fibrin glue was 46.4 percent (P < 0.05). CONCLUSIONS: The data fail to show improved outcomes when fibrin sealant is used in combination with an advancement flap compared with advancement flap alone for the management of complex anal fistulas.

Adult↗
PubMed2005

General method of preparation of mesoporous M/Si3N4 nano-composites via a non-aqueous sol-gel route.

We report a general method for the preparation of transition-metal silicon nitride nanocomposites; for example, mesoporous Pd-Si3N4 nanocomposite materials with high surface area were prepared by pyrolysis of a silicon palladium imide-chloride complex which was synthesized by reaction of silicon diimide gel with palladium chloride. These porous nanocomposites catalyse organic reactions.

Journal Article↗
PubMed2005

Analysis of heat generation using ultrasonic vibration for post removal.

This study measured the temperature of the root surface and post during the application of ultrasonic vibration to cemented posts to simulate post removal procedure. Root canal therapy was performed on ten extracted maxillary incisors. A stainless steel Parapost was cemented into each prepared post space. Ultrasonic vibration was applied to the post and temperatures were recorded at the coronal post and the cervical root surface. Data were analyzed with ANOVA using the independent variables of (a) time of ultrasonic application (15, 30, 45 and 60 s) and 2) location (post and root surface). Greater temperature increase was observed at the post (52.6 degrees C, SD 11.1; 82.6 degrees C, SD 20.1; 111.0 degrees C, SD 29.1; 125.3 degrees C, SD 33.2) compared to the root surface (9.5 degrees C, SD 4.6; 17.5 degrees C, SD 4.8; 25.4 degrees C, SD 7.3; 32.2 degrees C, SD 8.1) for each time period, P < 0.001. Ultrasonic application to the post for longer than 15 s generates high temperature on the root surface.

Analysis of Variance↗
PubMed2003

Unconditional preparation of entanglement between atoms in cascaded optical cavities.

We propose a scheme to unconditionally entangle the internal states of atoms trapped in separate high-finesse optical cavities. The scheme uses the technique of quantum reservoir engineering in a cascaded cavity-QED setting, and for ideal (lossless) coupling between the cavities generates an entangled pure state. Highly entangled states are also shown to be possible for realizable cavity-QED parameters and with nonideal coupling.

Journal Article↗
PubMed2002

Criteria for liquid crystal formation in 5-alkoxy-, 5-alkylamino-, and 5-alkanoyl-tropolone complexes of transition metals (Cu(II), Zn(II), Ni(II), Co(II), UO(2)(VI), VO(IV)). The first uranium metallomesogen. Crystal structure of bis(5-hexadecyloxytropolonato)copper(II).

The mesophase properties of bis(5-alkoxytropolonato)copper(II) complexes are reported and interpreted in terms of d-layer spacings, which indicate considerable intertwining of the alkyl chains. The mesogenic properties depend on the nature of the 5-substituent: to be mesogenic, it must be alkoxy with n > 8, and may not be 5-alkanoyl or 5-alkylamino. The nature of the metal is also important: to be mesogenic, it may be Cu(II) or UO(2)(VI) but not Ni(II), Zn(II), Co(II), or VO(IV). The crystal structure of bis(5-hexadecyloxytropolonato)copper(II) shows how, even in the crystalline state, molecular packing is dominated by the interactions between alkyl chains, together with copper-oxygen interactions. In the Cu(II) complexes, strong interactions occur between Cu atoms and O atoms of neighboring molecules. These are stronger than alkyl-alkyl interactions and therefore dominate alkyl-alkyl interactions between neighbors which otherwise govern the possibility and nature of mesogenic properties. The Cu.O interactions disrupt alkyl-alkyl chain interactions enough to produce a mesophase; such interactions do not obtain in the T(d)() Zn(II) and Co(II) complexes, and indeed, these complexes are not mesogenic. Likewise, alkyl chain interactions by the oxygens of the UO(2)(VI) lead to a mesophase, and U constitutes the heaviest metal ever placed into a mesogenic molecule. In the case of VO(IV), analogous synthetic steps from VOSO(4) led to a new series of binuclear complexes [(VO)(2)(SO(4))(5-alkoxytropoloato)(2)].

Journal Article↗
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Roy Meadow.

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Child Abuse↗