An arthroscopic evaluation of the anatomical "critical zone"

BACKGROUND

The "critical zone", a region of speculated vascularity, is situated approximately 10 mm proximal to the insertion of the supraspinatus tendon. Despite its obvious role as an anatomical landmark demarcator, its patho-anatomic nature has been identified as the source of rotator cuff pathology. Although many studies have attempted to evaluate the vascularity of this region, the architecture regarding the exact length, width and shape of the critical zone, remains unreported. This study aimed to determine the shape and morphometry of the "critical zone" arthroscopically.

MATERIALS AND METHODS

The sample series, which was comprised of 38 cases (n = 38) specific to pathological types, employed an anatomical investigation of the critical zone during routine real-time arthroscopy. Demographic representation: i) sex: 19 males, 19 females; ii) age range: 18-76 years; iii) race: white (n = 29), Indian (n = 7) and coloured (n = 2).

RESULTS

The incidence of shape and the mean lengths and widths of the critical zone were determined in accordance with the relevant demographic factors and patient history. Although the cresenteric shape was predominant, hemispheric and sail-shaped critical zones were also identified. The lengths and widths of the critical zone appeared markedly increased in male individuals. While the increase in age may account for the increased incidence of rotator cuff degeneration due to poor end-vascular supply, the additional factors of height and weight presented as major determinants of the increase in size of the critical zone.

CONCLUSIONS

In addition, the comparisons of length and width with each other and shape yielded levels of significant difference, therefore indicating a directly proportional relationship between the length and width of the critical zone. This detailed understanding of the critical zone may prove beneficial for the success of post-operative rotator cuff healing.

Caseous lymphadenitis in small ruminants in Egypt. Clinical, epidemiological and prophylactic aspects

OBJECTIVE

The aim of this study was to investigate the distribution of caseous lymphadenitis (CLA) among small ruminants in Egypt, identify risk factors associated with its occurrence and to analyze the efficacy of the vaccine for control of CLA.

MATERIAL AND METHODS

A total of 1206 sheep and 351 goats were examined clinically for CLA. The prevalence and the risk factors of CLA in small ruminant flocks were estimated and identified. Efficacy of the commercial vaccine Case-Bac (Colorado Serum Company, USA) was determined in a field study trial conducted on 15 CLA-free lambs. Follow-up of vaccination immune response was carried out using indirect ELISA.

RESULTS

Prevalence of superficial CLA was 6.7%. Clinically, CLA appeared as abscesses in superficial lymph nodes mostly of the head and neck. On the basis of a multivariate analysis which accounted for clustering at herd level, sheep were at risk of getting superficial CLA 3.5 times more than goats (p < 0.0001). Animals of fixed flocks were at risk of getting the superficial CLA 2 times more than animals in fixed-mobile flocks (p < 0.038). Serological follow-up indicated protective antibody titers for 6 months. In vaccinated animals clinical cases were not observed while they occurred among non-vaccinated sheep.

DISCUSSION

Prevalence of CLA varied among studied flocks even between those of the same breeding system due to complex and overlapping factors associated with each flock like introduction or culling rate of animals, care of shepherds or owners to deal with opened abscesses in addition to the average age of the animals within each flock. Breeding systems have observable effects on occurrence of CLA: infected sheep can transmit the infection to a large number of animals in a short period under the conditions of close contact and reduced air flow in covered sheds.

CONCLUSION AND CLINICAL RELEVANCE

Infected small ruminants in fixed flocks represent a risk factor for CLA for healthy ones. The vaccine used in the study provides an effective protection against new infections. So mass vaccination of small ruminants against CLA in Egypt has to be considered to minimize the disease prevalence.

Crown retention for non-retentive preparations using adhesive resin cements

This study examines the effect of preparing teeth with six varying convergence angles (ranging between 12 and 120 degrees) and height (1 and 2 mm) on the retention of cast gold crowns. Six groups of 4 human premolar teeth were prepared to give a flat occlusal surface in dentine with very short axial wall heights (1 or 2 mm) and variation in axial wall convergence (between 12 and 120 degrees). Impressions were recorded of the prepared teeth and custom castings made using a high copper content precious metal alloy. The castings were luted with an adhesive resin and stored in water at 37 degrees C for 24 hours prior to determining the pull-off force in an Instron Universal testing Machine at a cross head speed of 1mm min(-1). Twenty two of the twenty four tested specimens failed within the dentine of the tooth, irrespective of preparation orientation. Statistical testing using ANOVA demonstrated that there were no differences between the bond strength values for any of the preparation convergence angles or between preparations with 1 and 2 mm axial wall heights. This suggests that attachment strength of adhesively bonded castings with minimal axial wall height preparations is not influenced by the convergence angle of the preparation. The attachment strength exceeded that cohesive strength of the underlying dentine in nearly all of the adhesively luted restorations.

Bonding of crown and bridge adhesive resins to dentine

The shear bond strength of three adhesives, Panavia 21, Superbond, All Bond C&B Cement, and Variolink (a dual cure resin) to various dentine depths were determined. Fifteen human fully erupted permanent first and second molars were wet ground using 500 and then 800 grit abrasive papers to expose the superficial, middle and the deep dentine, for each adhesive tested. Five samples were prepared for each dentine depth. The adhesives were bonded to the samples using gelatine capsules and were matured for 24 h in water at 37 degrees C. The samples were debonded in shear using tensile testing machine at a cross-head speed of 1 mm/min. The data were analysed using ANOVA and the Tukey test. The fracture surfaces were examined by optical microscopy. The bond strength of Superbond to dentine was significantly higher (P<0.05) than any of the materials tested. The bond strength of all materials tested was shown to be affected by dentine depth, except for Superbond. Fractured dentine specimens showed that the samples of Superbond are almost cohesive (>90%), and the samples of other adhesives are mostly adhesive (>70%). These results confirm that Superbond is capable of forming a bond at various dentine depths.

Bonding of adhesive resin luting agents to metal and amalgam

The shear bond strength of three adhesives, Panavia 21, Superbond, All Bond C&B Cement, and a dual cure resin (Variolink), to Ni-Cr-Be (Rexillium III), Midigold (Type III gold) and Amalgam (Sybraloy) were determined. Fifteen samples were prepared using 800 grit abrasive papers for Ni-Cr and Midi-Gold, and 100 grit papers for amalgam. Ni-Cr-Be and Midi-Gold samples were sandblasted for 30 s and steam cleaned for 10 s. The adhesives were bonded to the samples using gelatine capsules and were matured for 24 h in water at 37 degrees C. The samples were debonded in shear using an Instron at a cross-head speed of 1 mm/min. The data was analysed using ANOVA and a Tukey test. The bond strength of Superbond to both metal alloys was significantly higher (P<0.05) than any of the materials tested, with the exception Panavia 21 to gold. The bond strength of All Bond C&B cement had shown to be not significant difference from those of Panavia 21 and Variolink, when bonded to Rexillium and Midi-Gold, respectively. The bond strength of All Bond C&B Cement to amalgam was significantly greater (P<0.05) than those of the other materials tested. The shear bond strength to gold showed lower bonding for all adhesives when compared with Rexillium (P<.001). The ranking of bond strength to both alloys was as follows: Superbond>Panavia 21>All Bond C&B>Variolink. The nature of substrate to be used for bonding and the adhesive material itself are important factors in bonding which can be achieved between cast metals and prepared teeth with amalgam filling. Superbond should be successful as an adhesive for the attachment of all substrates tested, with the possible exception of amalgam, for which All Bond C&B Cement gives the best result.

Polymerisation shrinkage of luting agents for crown and bridge cementation

The volumetric contraction of a variety of luting agents, including Panavia 21, All-Bond C&B Cement, Superbond., Variolink and zinc phosphate cement, was assessed and compared using a minimal transducer The contraction among the materials tested was determined from the post-gel linear displacement of a deflecting coverslip resting on 4 silicone rubber spacers between which a mixed material was centrally located. Finally, the rate and duration of shrinkage over a period of 60 minutes from the moment of rigid contraction for all materials were investigated, and the final shrinkage values among the materials tested were compared. The analysis of variance showed that there were highly significant differences (P< 0.001) between the materials and the mean of each group was significantly different from that of any of the other groups (Tukey's test). Superbond produced the highest values of the final polymerisation shrinkage, followed by All bond C&B, Variolink, Panavia 21 and zinc phosphate cement respectively. Also, there was a marked variation in the overall magnitude of shrinkage (from 1.34% to 4.62%) among the materials tested. The method used to measure the polymerisation shrinkage in the present study was shown to be a precise measure in that it produced consistent and reproducible results. It can also offer the ability to observe the development of polymerisation shrinkage against time, during the post-gelation phase, for a range of chemically-cured resin materials.

Clinical and therapeutic studies on mange in horses

At Kafr El-Sheikh province, Egypt, out of 117 examined drafting horses, mites were detected in 20 (17.09%) horses. The recovered mites were 14 Chorioptes, four Psoroptes and two Sarcoptes whereas mites were not detected in four cases clinically showed typical mange lesions. Interestingly, neither the age nor the sex of the examined horses had a clear influence on the prevalence of the infection. Clinical signs observed in mange infested horses were in the form of irregular skin lesions, severe itching and sometimes biting of affected skin areas and decrease feed consumption. The skin lesions mainly start as erythematous area followed by developing of papules and crust formation. Skin scratches as a result of traumatized lesions usually occurred. Hair was lost on the affected parts developing irregular alopecic areas. Distribution of the lesions was varied according to the type of mite. Chorioptic mite was detected in para-anal fold, distal portion of legs and tail lesions, Psoroptic mite was detected in withers, mane, shoulder and flank lesions whereas Sarcoptic mite was isolated mainly from lesions on the head and neck. Complete clinical and parasitological cure for mite infestation were obtained within 2 weeks in both moxidectin and ivermectin treated groups with 100% recovery rate. Our results indicated that moxidectin oral gel is effective and good alternative for the treatment of chorioptic mange in horse to avoid drug resistance that may develop as a result of the intensive use of ivermectin alone for long periods.

Film thickness and rheological properties of luting agents for crown cementation

The film thickness and rheological properties [viscosity and tan sigma], of different resin based crown and bridge luting agents, including Panavia 21, Superbond, All Bond C&B Cement, Variolink were compared with zinc phosphate cement. A modification of the method in ISO 9917 (1991) and a controlled stress rheometer were used to monitor the changes in the film thickness and rheological properties respectively. For each material, the film thickness and rheological characteristics were determined at 60s after start of mixing and then made at regular intervals until immediately before the material was set. For the initial film thickness, the difference among the values for Varionk, Superbond and zinc phosphate cement was not significant (P>0.05), and less than 25microm. The values for All Bond C&B Cement and Panavia 21 were at least twice that of the other materials tested. All Bond C&B Cement produced the highest film thickness value at both the initial period and at 240s. Regarding viscosity, Superbond had the lowest initial value but the highest value at 240s. Variolink gave the highest initial value of viscosity, but the differences in the initial values among the other materials were small. During the whole period of testing, zinc phosphate cement gave the highest values of tan sigma, and Panavia 21 showed no significant change in any of the measured properties. The methods were able to distinguish the behaviour of different cement materials. Some resin cements produce larger than optimal values of film thickness and in some cases this is related to a rapid increase in viscosity after mixing. It is expected that differences in the ability of cements to form thin films will affect the seating of cemented restorations.

Development and evaluation of quantitative-competitive PCR for quantitation of coxsackievirus B3 RNA in experimentally infected murine tissues

A method is described for quantitation of enterovirus RNA in experimentally infected murine tissues. Viral RNA was extracted from tissue samples and amplified by reverse transcriptase PCR in the presence of an internal standard RNA. The ratio of PCR product derived from viral RNA and internal standard RNA was then determined using specific probes in a post-PCR electrochemiluminescent hybridization assay. This provided an estimate of the viral RNA copy number in the original sample, and detection of PCR product derived from internal standard RNA validated sample processing and amplification procedures. RNA copy number correlated with viral infectivity of cell culture-derived virus, and one tissue culture infective dose was found to contain approximately 10(3) genome equivalents. The ratio of RNA copy number to infectivity in myocardial tissue taken from mice during the acute phase of coxsackievirus B3 myocarditis was more variable ranging from 10(4)-10(7), and was dependent on the stage of infection, reflecting differential rates of clearance for viral RNA and viral infectivity. The assay is rapid, and could facilitate investigations which currently rely upon enterovirus quantitation by titration in cell culture. This would be useful for experimental studies of viral pathogenesis, prophylaxis and antiviral therapy.

Synthesis and pharmacological effect of substituted phenyl-4-(2-chloroethyl)tetrahydro-1,4-oxazine hydrochlorides

Substituted phenyl-4-(2-chloroethyl)tetrahydro-1,4-oxazine hydrochlorides were prepared by treating the corresponding amino alcohols with thionyl chloride. Since these compounds are considered to be monofunctional 2-haloalkylamine type agents, they were tested for possible alpha-adrenergic blocking activity using the rat anococcygeus muscle. The pharmacological action of this series of compounds is discussed.