Histological evaluation of dog permanent teeth after traumatic intrusion of their primary predecessors

Abstract –  The aims of this study were to analyze the histomorphology of developing permanent teeth whose primary teeth had suffered traumatic intrusion, as well as to compare the influence of immediate extraction of the intruded tooth to passive re-eruption. Nine dogs from 45 to 50 days old were submitted to the intrusion of the maxillary central and lateral primary incisors using a force applicator adapted to the teeth incisal cuspids. The right side intruded teeth were kept in their sockets and the ones on the left side were extracted 30 min later. After a postoperatory periods of 30 and 60 days, four (group 1) and five (group 2) dogs, respectively, were killed by perfusion. The histological evaluations showed that, in group 1, alterations had occurred in the odontoblastic layer and deposition of the enamel matrix had taken place in some specimens while in group 2, a portion of non-mineralized matrix was observed. We concluded that the morphological changes were because of the immediate trauma of intrusion. No differences were found between the groups where the primary tooth was immediately extracted or left to passively re-erupt.     

A new approach to the limiting dilution assay

Improved methods of human immunodeficiency virus isolation have sparked an increased interest in determination of the number and proportion of infected cells in plasma samples. The limiting dilution assay is a popular method of determining the proportion of infected cells. We propose a new estimator of the proportion of infected cells based on an underlying Markov chain model for the progression of infected cells to further flasks in the series. This method should improve both design and analyses of these assays.     

Correlates of sexual function among multi-ethnic middle-aged women: results from the Study of Women's Health Across the Nation (SWAN)

OBJECTIVE: To examine sexual function in a cohort of Baby Boomer women of diverse racial/ethnic backgrounds; to compare differences between pre-and early perimenopausal women; and to identify sociodemographic, health-related, and psychosocial (including psychological, behavioral, and relationship) factors related to sexual function. DESIGN: Six domains of sexual function were studied in 3,167 women in the baseline cohort of the Study of Women's Health Across the Nation (SWAN). Participants were 42 to 52 years old, pre-or early perimenopausal, and not using hormones. The study sample included non-Hispanic white, African American, Hispanic, Chinese, and Japanese women. RESULTS: Early perimenopausal women reported greater pain with intercourse than premenopausal women (P = 0.01), but the two groups did not differ in frequency of sexual intercourse, desire, arousal, or physical or emotional satisfaction. Variables having the greatest association across all outcomes were relationship factors, the perceived importance of sex, attitudes toward aging, and vaginal dryness. Despite controlling for a wide range of variables, we still found ethnic differences for arousal (P < 0.0001), pain (P = 0.03), desire (P < 0.0001), and frequency of sexual intercourse (P = 0.0003). African American women reported higher frequency of sexual intercourse than white women; Hispanic women reported lower physical pleasure and arousal. Chinese women reported more pain and less desire and arousal than the white women, as did the Japanese women, although the only significant difference was for arousal. CONCLUSIONS: Relationship variables, attitudes toward sex and aging, vaginal dryness, and cultural background have a greater impact on most aspects of sexual function than the transition to early perimenopause.     

Treatment of postoperative enterocutaneous fistulas by high-pressure vacuum with a normal oral diet

BACKGROUND/AIMS: Enterocutaneous fistulas are associated with prolonged hospital stay, high morbidity/mortality, and increased hospital costs. This study aims to describe the use of a vacuum system and normal oral diet in dealing with this problem. METHODS: Seventy-four consecutive patients with recent and defined external postoperative fistulas were analyzed. Abdominal imaging was used to exclude abscess and distal obstruction. The fistula tract was sealed with Foley catheter, connected to a negative pressure flask, changed daily for 5, 10 or 15 days, as necessary. A normal oral diet was permitted. RESULTS: No patient died. Serum albumin and transferrin showed significantly higher levels at the end of treatment than at the beginning. The moderate and low-output fistulas had the best results (97% closed). Forty-eight (65%) fistulas closed after 5 days, 16 (22%) after 10 days and 4 (5%) after 15 days. Treatment failed in 6 (8%) patients, who subsequently underwent surgery. The fistula did not close in 1 patient with a low output. The cost of the treatment was USD 41.75/day and it was considered cost-effective. CONCLUSIONS: The vacuum system demonstrated good results in the treatment of fistulas. It included simplicity, low cost, short hospital stay, absence of skin breakdown, normal eating, good nutrition and activity patterns.     

Generation of 3D retina-like structures from a human retinal cell line in a NASA bioreactor

Replacement of damaged cells is a promising approach for treatment of age-related macular degeneration (AMD) and retinitis pigmentosa (RP); however, availability of donor tissue for transplantation remains a major obstacle. Key factors for successful engineering of a tissue include the identification of a neural cell line that is: homogeneous but can be expanded to give rise to multiple cells types; is nontumorigenic, yet capable of secreting neurotrophic factors; and is able to form three-dimensional (3D), differentiated structures. The goal of this study was to test the feasibility of tissue engineering from a multipotential human retinal cell line using a NASA-developed bioreactor. A multipotential human retinal precursor cell line was used to generate 3D structures. In addition, retinal pigment epithelium (RPE) cells were cocultured with neural cells to determine if 3D retinal structures could be generated in the bioreactor with cells grown on laminin-coated cytodex 3 beads. Cell growth, morphology, and differentiation were monitored by light and scanning electron microscopy, Western blot analysis, and analysis of glucose use and lactate production. The neuronal retinal precursor cell line cultured in a bioreactor gave rise to most retinal cell types seen in monolayer culture. They formed composite structures with cell-covered beads associated with one another in a tissue-like array. The beginning of layering and/or separation of cell types was observed. The neuronal cell types previously seen in monolayer cultures were also seen in the bioreactor. Some of the retinal cells differentiate into photoreceptors in the bioreactor with well-developed outer segment-like structures, a process that is critical for retinal function. Moreover, the neuronal cells that were generated resembled their in vivo phenotype more closely than those grown under other conditions. Outer segments were almost never seen in the monolayer cultures, even in the presence of photoreceptor-inducing growth factors such as basic fibroblast growth factor (bFGF) and transforming growth factor (TGF-alpha). Muller cells were occasionally seen when retinal, RPE cells were cocultured with retinal cells in the bioreactor. These have never been seen in this retinal cell line before. Cells grown in the bioreactor expressed several proteins specific for the retinal cell types: opsin, protein kinase C-alpha, dopamine receptor D4, tyrosine hydroxylase, and calbindin.     

Caffeine-induced place and taste conditioning: production of dose-dependent preference and aversion

Although caffeine may be the most widely used behaviorally active drug, few studies have examined its rewarding properties. In the present study, the designs of place-conditioning and taste-conditioning paradigms were combined in a single experiment to provide two independent measures of drug reward. During 3 preconditioning sessions, undrugged rats received access to 2 distinctive chambers connected by a small tunnel. During the 8-session conditioning phase, groups were given home cage access to either a sweet or salty solution, administered caffeine (0.3, 1.0, 3.0, 10.0, 30.0 mg/kg IP; 30.0 mg/kg SC), and confined to one of the chambers. On alternate sessions, rats were given home cage access to the remaining solution, injected with the vehicle, and confined to the opposite chamber. On test sessions 1 and 2, undrugged animals were given home cage access to one of the flavored solutions and water, and then allowed access to both conditioning chambers. On test session 3, rats were given access to both flavored solutions, injected with the drug used during conditioning, and again allowed access to both chambers. Caffeine (3.0 mg/kg) produced a significant place preference. The highest dose (30.0 mg/kg IP and SC) produced significant place and taste aversions. A control group given (+)-amphetamine illustrated a significant place preference and taste aversion as expected. Thus caffeine appeared to produce a dose-dependent biphasic effect; a lower dose was rewarding, whereas higher doses produced aversions to environmental stimuli associated with the drug.