Evaluation of consecutively placed unloaded root-form and plate-form implants in adult Macaca mulatta monkeys

The present paper describes 18 consecutively-treated non-human primates (Macaca mulatta) as part of a balanced block design study of 36 animals to examine osseointegration in root- and plate-form implants prepared by atraumatic preparation of bone. Clinical measurements around selected teeth and digital radiology were utilized to monitor periodontal disease and bone deposition around the unloaded implants. Once a month scaling procedures were utilized as a means of preventing further advance of periodontal disease. Results indicate that once-monthly regimen of scaling and root planing can prevent attachment loss of natural teeth and will not interfere with the healing of either type of implant; once-monthly scalings produce significant reduction in redness (P < .05) and reduced probing depths (P = .01). A second finding is that both root and blade implants show radiographic evidence of osseointegration in this primate model. The quantitative analysis demonstrates bone gain is not stabilized until 6 months after healing. The data may indicate that occlusal loading of mandibular implants at 3 months may be premature.     

Extinction deficits in socially isolated rhesus monkeys (Macaca mulatta).

In a study with 18 5-yr-old rhesus monkeys, 6 Ss reared in total isolation made more unrewarded responses and took longer to stop responding in the face of nonreward than 12 Ss raised in partial isolation or normally. It is suggested that isolates have difficulty inhibiting high-probability responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Monoamine metabolite levels in CSF of SIV-infected rhesus monkeys (Macaca mulatta)

Increasing evidence suggests the involvement of the basal ganglia in HIV-1-infected patients. We used SIV-macaques, an animal model of HIV-1 infection, to investigate changes in CSF biogenic amine metabolites over time and compared them with control animals. The dopamine and serotonin metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), were analysed by reverse-phase chromatography with electrochemical detection. DOPAC concentrations were significantly increased in SIV-infected animals compared with controls. 5-HIAA and HVA remained unchanged. However, the longitudinal assessment of metabolites up to 3 months post-infection revealed a significant increase in 5-HIAA. Our results reflect the effects of SIV early stage infection on monoamine systems in brain and further validate the simian model for AIDS research.     

Aerosolized staphylococcal enterotoxin B-induced pulmonary lesions in rhesus monkeys (Macaca mulatta)

The pathology of aerosolized staphylococcal enterotoxin B (SEB) was studied in the nonhuman primate. Six juvenile rhesus monkeys that received multiple lethal inhaled doses of SEB developed diarrhea and vomiting within 24 hr followed by depression, dyspnea, and shock. Three of 6 animals died by 52 hr. The most striking gross lesion in all 6 monkeys was diffuse severe pulmonary edema. Histologically, edema fluid was present within the peribronchiolar, peribronchial, and perivascular interstitium, alveolar septa, and alveoli. The adventitia of pulmonary vessels was infiltrated by lymphocytes, macrophages, and fewer neutrophils. Numerous large lymphocytes with occasional mitotic figures were within pulmonary vessels, often occluding alveolar capillaries. These cells were strongly immunoreactive with monoclonal antibodies against CD3, establishing them as T cells. Ultrastructurally, endothelial cell junctions were intact, and endothelial cells and type I pneumocytes contained numerous pinocytotic vesicles. Alveolar septal interstitial spaces were expanded by edema. The mechanism of these SEB-induced pulmonary lesions was not determined. We hypothesize that cytokine production by activated T cells may have caused vascular permeability changes leading to widespread pulmonary edema and shock.     

Neuropathogenesis induced by rhesus cytomegalovirus in fetal rhesus monkeys (Macaca mulatta)

In a double-blind study, 655 sputum specimens were obtained from individuals suspected of having tuberculosis and were analyzed for the presence of Mycobacterium tuberculosis and rifampin susceptibility with use of a polymerase chain reaction (PCR)-based universal heteroduplex generator assay (PCR/UHG-Rif). Of the specimens containing viable M. tuberculosis, 100% of the smear-positive (n = 41) and 50% of the smear-negative (n = 6) specimens tested positive for the organism by PCR/UHG-Rif. Nineteen of 537 culture-negative specimens tested positive for M. tuberculosis by PCR/UHG-Rif and were from patients with confirmed tuberculosis who were receiving antituberculosis therapy at the time of specimen collection. Thirty-five specimens contained nontuberculous mycobacteria and were negative by PCR/UHG-Rif. Genotypic evidence of rifampin resistance in five of six culture-confirmed, rifampin-resistant isolates was obtained by PCR/UHG-Rif, yielding a sensitivity and specificity for the assay of 83% and 98.2%, respectively. These results demonstrate the feasibility of using a PCR-based assay directly on sputum specimens for simultaneous detection of M. tuberculosis and rifampin susceptibility, and they suggest that patients with smear-positive, untreated tuberculosis and those presenting with suspected drug-resistant tuberculosis are the most appropriate groups for testing by PCR/UHG-Rif.     

Pulpotomy as an alternative to canine tooth extraction in monkeys [Macaca mulatta]

An effective method for sealing pulp canals after partial removal of canine tooth crowns from adult rhesus monkeys is described.     

Regulation of food intake during intermittent and continuous cross circulation in monkeys (Macaca mulatta).

Established cross-circulation between 4 pairs of chair-restrained male rhesus monkeys in order to investigate the role of blood-borne factors in control of food intake. Femoral arterial-venous shunts were implanted and intermittent or continuous cross-circulation was conducted over periods of 5-69 days prior to onset of immune reactions. A liquid-diet feeding system recorded ingestive behavior. Blood-borne factors from a partially or totally deprived S produced no significant or sustained alteration in the pattern of ingestion or the amount taken by a feeding S. The latency and initial rate of feeding by the deprived S were not affected by cross-circulation with a free-feeding S. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective autonomic blockade of conditioned and unconditioned cardiovascular changes in rhesus monkeys (Macaca mulatta).

Examined changes in heart rate and systolic and diastolic blood pressures in 8 rhesus monkeys during 6 sessions of differential classical conditioning. The conditioned stimuli consisted of tones differing in frequency, and the unconditioned stimuli consisted of tail shock. Both the CRs and UCRs consisted of increases in heart rate and in systolic and diastolic pressures, but blood pressure CRs sometimes occurred in the absence of heart rate CRs. In Exp II, graded doses of the selective blocking agents propranolol, phentolamine, and atropine methylnitrate were systemically administered to 4 of the Ss prior to additional conditioning sessions. Results suggest that the CRs and UCRs were mediated by both sympathetic and parasympathetic influences. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Uncertain responses by humans and rhesus monkeys (Macaca mulatta) in a psychophysical same-different task

The authors asked whether animals, like humans, use an uncertain response adaptively to escape indeterminate stimulus relations. Humans and monkeys were placed in a same-different task, known to be challenging for animals. Its difficulty was increased further by reducing the size of the stimulus differences, thereby making many same and different trials difficult to tell apart. Monkeys do escape selectively from these threshold trials, even while coping with 7 absolute stimulus levels concurrently. Monkeys even adjust their response strategies on short time scales according to the local task conditions. Signal-detection and optimality analyses confirm the similarity of humans' and animals' performances. Whereas associative interpretations account poorly for these results, an intuitive uncertainty construct does so easily. The authors discuss the cognitive processes that allow uncertainty's adaptive use and recommend further comparative studies of metacognition.     

Early experience and complexity of social organization in groups of young rhesus monkeys (Macaca mulatta).

Found that 2 6-member social groups of young rhesus monkeys, one socially deprived and the other raised with mother and age-mates, showed marked differences in the complexity of social organization. Compared to deprived Ss, experienced Ss interacted more often as trios and larger subgroups, and the response structure of their triadic subgroups was more complex. Only in the experienced group did functional aspects of triadic interactions suggest that 1 individual recognized the status relations between the other participants. These findings indicate that early social experience affects levels of social competence that transcend variations in ethologically derived response patterns and that cannot be seen in arranged dyadic encounters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship of tooth size to body size in a population of rhesus monkeys (Macaca mulatta)

Tooth areas correlate significantly with long bone measurements in a skeletal population of rhesus monkeys from Cayo Santiago. Correlations are relatively large for the troop as a whole, as well as for males and females separately. Femur and humerus length measurements show the higheres correlations with tooth size.     

Microbiology of ligature-induced marginal inflammation around osseointegrated implants and ankylosed teeth in cynomolgus monkeys (Macaca fascicularis)

The aim of this study was to characterize the changes in the quantitative expression of beta 2-integrins and L-selectin detected by means of fluorochrome-conjugated monoclonal antibodies and flow cytometry on leukocytes in the systemic circulation after a major musculoskeletal trauma, i.e. hip replacement surgery, and to relate these changes to parameters of the acute-phase response [plasma acute-phase reactants (C-reactive protein, CRP, and interleukin-6, IL-6) and parameters of coagulation activation (thrombin-antithrombin III complexes, TAT)]. Eight patients with either primary or secondary osteoarthritis of the hip received uncemented total hip prostheses. LFA-1 (CD11a/CD18) was upregulated on granulocytes during the operation. MAC-1 (CD11b/CD18) expression on monocytes increased to peak levels 20 h after surgery, whereas the L-selectin (CD62L) expression on monocytes and granulocytes reached peak values at the end of surgery. The changes in expression of LFA-1 on monocytes, MAC-1 on granulocytes and p150,95 (CD11c/CD18) on monocytes and granulocytes during and after the operation did not reach statistical significance. TAT and IL-6 increased during surgery and reached peak values at the end of the operation and 20 h after surgery, respectively. In contrast, CPR concentrations increased after surgery with peak levels 44 h postoperatively. Significant upregulation of LFA-1 on granulocytes and L-selectin on monocytes and granulocytes preceded the increase in IL-6 which again preceded the increase in CRP. However, the up- or downregulation of leukocyte beta 2-integrins and L-selectin during and after surgery was not significantly correlated with the increase in IL-6. The increases in TAT correlated well with the upregulation of L-selectin on monocytes, but not with the beta 2-integrins known to participate in the coagulation process in vitro. The rise in CRP was inversely correlated with the maximal increase in expression of MAC-1 on monocytes. In conclusion, the changes in leukocyte adhesion molecules during and after surgery indicate changes in critical leukocyte functions. The lack of correlation between quantitative up- and downregulation of leukocyte beta 2-integrins and parameters of the acute phase response suggests that these processes are regulated through independent pathways or that functional up- and downregulation of adhesion molecules, shedding, leukocyte-endothelial adhesion and mobilization of new unactivated cells may result in a net estimate of leukocyte activation not suspected to be positively correlated to acute-phase reactants.     

Tissue regeneration in bony defects adjacent to immediately loaded titanium implants placed into extraction sockets: a study in dogs

In this study of six greyhound mandibles, 24 implants were placed into extraction sockets. Eighteen of the implants were connected with abutments and immediately placed into normal function, and the remaining six submerged implants served as controls. At placement, dehiscence areas were created adjacent to 12 of the implants to study bone regeneration in extended membrane-protected defects. Six of the defects were covered with expanded polytetrafluoroethylene membranes, and six of the defects were augmented with autologous bone grafts and covered with expanded polytetrafluoroethylene material. The clinical and radiographic evaluations demonstrated that all implants achieved functional osseointegration and no implants were lost. Implant sites where membranes were used to regenerate bone over dehiscence defects demonstrated a high rate of membrane exposure and variable response to treatment. On completion of the study at 16 weeks, histomorphometric analysis demonstrated osseointegration with direct bone-to-implant contact for all implants, although the percentage of contact varied considerably. Histomorphometry indicates that the quality of osseointegration may be less favorable than the clinical and radiographic result would suggest.     

Ligature-induced marginal inflammation around osseointegrated implants and ankylosed teeth: stereologic and histologic observations in cynomolgus monkeys (Macaca fascicularis)

The aim of the investigation was to provide quantitative and qualitative histologic data on marginal inflammation around osseointegrated implants. The significance of the lack of a periodontal ligament in the initial breakdown phase of supporting tissues in implants was examined by comparing stereologic and histologic manifestations of ligature-induced marginal inflammation around osseointegrated implants with those around ankylosed and normal control teeth in 8 cynomolgus monkeys (Macaca fascicularis). Clinical and radiographic findings have been reported elsewhere. The marginal connective tissue around ligated implants was infiltrated by a significantly increased total number of lymphocytes, plasma cells, and neutrophils compared to non-ligated implants and teeth. The total number of lymphocytes around ligated implants was significantly higher than around ligated ankylosed and normal control teeth. There were, however, no significant differences in the total number of plasma cells and neutrophils within the ligated group. Osteoclasts were exclusively observed around ligated implants and ankylosed teeth. Although variations in microbiota and susceptibility of different jaw positions to periodontal break-down may influence the results of the present study, the results seem to substantiate the theory that marginal inflammation around implants and ankylosed teeth may have more serious implications than does marginal inflammation around teeth with a periodontal ligament. Since presence of osteoclasts was not related to the absence of cervical cementum with inserting gingival fibers around ligated ankylosed teeth, the increased susceptibility of bone loss of implants is probably not caused by the absence of these tissue components. In contrast, the histologic observations seem to support that the increased susceptibility for bone loss around implants may be related to the absence of a periodontal ligament.     

Matching within and between sense modalities in the monkey (Macaca mulatta).

Trained 18 rhesus monkeys on a series of visual matching problems and tested for cross-dimensional transfer. Performance of a true matching group was at the same time compared with that of a "false matching" (i.e., conditional reaction) group. Training was then given on a series of cross-modal (visual-tactual) matching (CMM) problems, again with true vs false matching comparisons. Finally, a test for CMM using a single-sample technique was given. Evidence was found for cross-dimensional transfer of visual matching, but none for differences between initial true and false visual, or cross-modal, matching tasks. Nor was evidence for a genuine CMM ability found in the results of the single-sample CMM tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Properties of soluble and membrane intestinal hydrolases in Macaca rhesus monkeys

Evidence from several central nervous system (CNS) inflammatory disease models suggests that intrathecal complement synthesis may contribute to early inflammatory events in the brain. In this study, we examined the expression of the receptor for C5a (C5aR), a potent inflammatory and chemotactic factor, in the brains of transgenic mice with constitutive astrocyte expression of interleukin-3 (IL-3), a hematopoietic and immunomodulatory cytokine. By in situ hybridization, we demonstrated that cells infiltrating the cerebellar meninges, the cerebellum, and demyelinating lesions in the cerebellum were strongly positive for C5aR mRNA. By immunohistochemistry, the infiltrating cells expressing the C5aR were identified as macrophages based on staining with antibodies to the complement receptor type 3 and F4/80, a mouse macrophage-specific marker. In addition, some of the cells in cerebellar lesions were positive for the astrocyte-specific marker, glial fibrillary acidic protein, suggesting that a subpopulation of astrocytes in these lesions express elevated levels of the C5aR. Increased C5aR expression was also observed in cortical neurons in the occipital cortex and in pyramidal neurons in the cornu ammonis and subiculum of the hippocampus, at both the protein and mRNA levels. These data suggest that IL-3 may play an immunomodulatory role in C5aR expression on several cell types in the brain and that increased C5aR expression correlates with the pathology seen in this model. The transgenic mice used in this study provide a useful tool for characterizing the mechanism of regulation of the C5aR expression and for examining the functions of this chemotactic receptor in CNS inflammation.