Guided tissue regeneration using rigid absorbable membranes in the dog model of chronic furcation defect

OBJECTIVE

Absorbable membranes are used to promote the regeneration of periodontal defects by Guided Tissue Regeneration (GTR). However, their collapse into the defect is commonly reported, impairing regeneration. Therefore, absorbable but rigid membranes aiming at preventing such collapse were developed and analyzed in periodontal regeneration.

MATERIALS AND METHODS

Membranes were analyzed in class II furcation defects in dogs; procedures included periodontal disease induction, prophylaxis and GTR (treated groups) or open flap debridement alone (control group). For GTR, the membranes were made of either 25% hydroxyapatite (HA) in polyhydroxybutyrate matrix (PHB) or 35% HA in PHB. Animals were clinically evaluated for gingival recession, clinical attachment level (CAL) and biopsies were collected at 60 and 120 days. Bone volume, trabeculae number, trabecular thickness and trabecular separation were quantified by micro-computed tomography, followed by histology.

RESULTS

Membrane exposure was observed in both treated groups (25 and 35% HAP) from the 8(th) day after surgery, continuously progressing until 120 days. Mean CAL for all groups remained above normal values for dogs. Bone volumetric values were not significantly different. Partial formation of bone, cementum and periodontal ligament was observed in treated groups. An inflammatory infiltrate was observed in the dense connective tissue that partially filled the center of the treated defects with active osteoclasts on bone surface.

CONCLUSION

Although partial regeneration of the defect was observed, it was limited by wound contamination. Consequently, rigid absorbable membranes made of HA and PHB failed to improve the regeneration of class II furcation defects in dogs.

Antinociceptive effect from Ipomoea cairica extract

Ipomoea cairica L. Sweet (Convolvulaceae) is used in Brazilian folk medicine for the treatment of rheumatism and inflammations. Ipomoea cairica ethanolic extract (100, 300, 1000 and 3000 mg/kg; per os) induced dose-dependent reduction of response in the formalin test inflammatory phase in mice. The same dose range did not modify neurogenic pain in formalin test, tail-flick reflex latency, carrageenan-induced paw edema, and Rota-Rod test motor performance. From the bio-active fraction 3,5-di-O-caffeoylquinic acid and 4,5-di-O-caffeoylquinic acid were obtained. These compounds have been previously reported to have analgesic and antioxidative effects. A possible explanation for the antinociception is that somehow the compounds present in the extract reduced the release of pro-nociceptive mediators unrelated to carrageenan-induced edema, such as histamine. Interestingly, caffeoylquinic acid derivatives have been reported to inhibit histamine release on in vitro models. The isolated caffeoylquinic acids could explain, at least in part, the antinociceptive effect of Ipomoea cairica polar extract.

Study of zinc and growth hormone in sickle cell disease

About 25% of children with sickle cell disease (SCD) have statural deficit and retarded skeletal maturation and pubertal development. These disorders have been attributed to low serum concentrations of zinc. We report the study of serum zinc in 34 patients with SCD, of whom 17 had statural deficit (SCS group) and 17 without growth deficiency (SCN group). They were compared with 20 normal children (N group). GH secretion and thyroid function were investigated in the group with short stature (SCS) in order to rule out GH deficiency and hypothyroidism. The mean serum zinc concentration was 108.45+/-22.888 microg/100 ml in the N group, 87.529+/-30.069 microg/100 ml in the SCN group and 82.765+/-34.766 microg/100 ml in the SCS group. There was a statistically significant difference between the mean of the N group and the mean of the SCN group (p<0.05) but no difference was found between the two groups of patients (N>SCN=SCS). Although there is a well-established zinc deficiency in patients with SCD, the statural retardation found in the SCS group could not be attributed only to zinc deficiency. Many other severe metabolic disturbances are also involved.

A prospective and randomized study using ribavirin as monotherapy for the treatment of naïve patients with chronic hepatitis C

In order to evaluate the response to ribavirin in previously untreated patients with chronic hepatitic C, 39 patients were selected for a double-blind prospective and randomized trial, and divided into two groups: ribavirin-group (19 patients) and placebo-group (20 patients). Ribavirin was administered orally for 24 weeks (600 mg/day, followed by 1,000 mg/day and 1,200 mg/day each one for 8 weeks). After 3 months of drug administration, the patients were evaluated by measuring biochemical, virologic and histologic responses. After this phase, ribavirin was offered to the patients who had received placebo (second phase). The results showed that the patients who received ribavirin showed a higher reduction in serum alanine aminotransferase (ALT) activity than patients in the placebo group. Among the patients in the ribavirin-group, a complete biochemical response (ALT levels normalized) was observed in 3 patients (16%), and a partial response (reduction greater than 50% of the initial value of ALT activity) in 4 (21%). In the 20 patients in the placebo group, only 1 showed a partial response (5%). In the second phase of the study, among 16 patients who received ribavirin, 4 (25%) showed a complete and 5 (31%) a partial biochemical response. HCV-RNA did not become negative in any patient during the two phases. A reduction in the score of portal and lobular activity was observed in patients who received ribavirin, but statistical analysis did not identify differences. This study showed that ribavirin alone induces a biochemical response (ALT reduction) in some patients with chronic hepatitis C, which may be associated with a reduction in hepatic inflammatory activity reduction, but the changes are not sufficient to recommend initial monotherapy with ribavirin.

Clinical problems of sloths (Bradypus sp. and Choloepus sp.) in captivity

A 20-yr retrospective study of disease prevalence was carried out for 51 sloths (34 Bradypus sp. and 17 Choloepus sp.) at the São Paulo Zoo. A total of 81 clinical disorders were detected, including nutritional (45.7%), digestive (12.3%), and respiratory (12.3%) problems and injuries (6.1%). A definitive diagnosis was not possible in 8.6% of the cases. The incidence of disease varied according to seasonal climate (winter, 32.5%; spring, 24%; summer, 22.9%; autumn, 20.5%), time in captivity (96.4% of diseases occurred within the first 6 mo and 3.6% occurred thereafter), and type of enclosure (quarantine cage, 96.4%; exhibition enclosure, 3.6%). Both young animals (86.7%) and adults (3.2%) were affected. Parasites were identified by fecal examination in 45.4% of animals with clinical illness (Ascaris sp., 80%; Coccidia sp., 20%). Bacteria such as Salmonella enteritidis, Escherichia coli, and Citrobacter freundii were isolated from feces and/or organs. The first 6 mo in captivity are critical for these animals. Proper management and early identification of medical conditions in captivity have implications for sloth population in the wild.

Clinical disorders in armadillos (Dasypodidae, Edentata) in captivity

The major health problems found in 113 armadillos are presented and correlated with management in captivity. The most common of 217 recorded clinical disorders involved injury (28.5%), digestive system (17.9%), respiratory system (15.2%), nutritional deficiency (13.3%), skin problems (3.6%), septicaemia (1.8%), nervous system (1.3%), urinary system (0.9%) and effects of environmental (0.9%), with 14.7% of the cases inconclusive. Internal parasites were identified in 42.0% of faeces samples, mainly eggs of helminths (66.6%), of which the commonest were Ancylostoma sp. (33.3%), Strongyloides sp. (30.5%), Ascaris sp. (25.0%), Trichuris sp. (11.1%), and also protozoa (13.0%). Enterobacteriaceae were the bacteria most frequently isolated, with Escherichia coli the most prevalent, followed by Salmonella sp. and Enterobacter aerogenes. The most successful treatments are listed. The influence of some captive factors on the onset of the diseases was also analysed: donated animals 91.1% and zoo born 8.8%; quarantine enclosure 84.0% and exhibition 15.0%; and related to time in captivity, 92.2% occurred with animals in the first 6 months in the zoo and 7.8% with animals more than 6 months.

Clinical disorders observed in anteaters (Myrmecophagidae, Edentata) in captivity

The major health problems found in 103 captive lesser anteaters (Tamandua tetradactyla) and giant anteaters (Myrmecophaga tridactyla), family Myrmecophagidae, are presented and correlated with management. The most common of 200 recorded clinical disorders involved the digestive system (26%), nutritional deficiency (20%), injury (15.5%), respiratory system (10%), skin (7%) and circulatory system (4.5%), but 13% of the cases were inconclusive. Parasites were identified in 48.5% of faecal samples, mainly the eggs of nematodes (40%), of which the commonest were Trichuris spp (28%) and Strongyloides spp (11%); protozoa (16%), of which the commonest were Eimeria spp (10%), Entamoeba spp (5%) and Giardia spp (1%); and cestodes (8%) and acanthocephalids (1%). Bacteria cultured from the various materials included Salmonella enteritidis, S. cholerasuis, Escherichia coli, Enterobacter aerogenes, Streptococcus spp and Staphylococcus spp. The ectoparasites found were Amblyomma spp and Otodectis spp (Arthropoda, Acaridae).

Comparison of three different schedules of vaccination against hepatitis B in health care workers

Health care workers (HCW) are a group at risk for hepatitis B virus (HBV) infection; as a result, vaccination is recommended. However, elevated cost of the vaccination schedule is one of the limiting factors to this approach. Our aim in this study was to evaluate alternative schedules for vaccination against hepatitis B, in order to obtain safe immunization with reduced costs. We studied 300 HCW, randomized to be submitted to one of three vaccination schedules against hepatitis B: Group A--three doses of 20 micrograms i.m. (n = 103); Group B--first dose i.d. (2 micrograms), second and third doses i.m. (20 micrograms) (n = 97); Group C--first and second doses i.d. (2 micrograms), third dose i.m. (20 micrograms) (n = 100). All individuals received recombinant vaccine at 0, 1 and 6 months. After the first dose, there was no difference among the three schedules, either in terms of anamnestic response or in seroconversion rate. After the second dose, there was statistical difference among the three schedules (A > B > C), in terms of seroconversion rates. After the third dose, seroconversion rates were 92.2% in Group A and 92.8% in group B; geometric mean titers (GMT) in Group B (789.6 UI l-1) were similar to group A (1248.0 UI l-1). Group C presented a seroconversion rate of 78% and a GMT of 323.0 UI l-1, both statistically inferior to other schedules. We concluded that the schedule applied in Group B had similar results when compared to schedule A, with estimated savings of 30% in vaccine costs.(ABSTRACT TRUNCATED AT 250 WORDS)