Evaluation of hydroxylapatite/poly(l-lactide) composites: physico-chemical properties

The aim of this in vitro study was to examine the physico-chemical behaviour of hydroxylapatite/poly(l-lactide) (HA/PLLA) composites in solution tests. The polymer PLLA, the composites 30 wt% HA/PLLA (C30) and 50 wt% HA/PLLA (C50) and a one-side HA-coated PLLA (HAcP) were evaluated. Rectangular specimens were incubated in various acellular aqueous buffer solutions [citrate, Gomori's and phosphate-buffered saline (PBS)] up to 24 weeks. Data for cumulative release of calcium, phosphate and l-lactate release in solutions containing C30 or C50 showed linear patterns. Release data for solutions containing HAcP combined with scanning micrographs, X-ray microanalysis and X-ray diffraction patterns of the specimens in time showed that the plasma-sprayed HA coating on PLLA dissolves significantly, progressively in the first weeks and almost completely within the tested period of 24 weeks in vitro. A precipitate of scaly crystallites (calcium phosphates) was observed at the HA coating-PBS interface. After 24 weeks incubation all materials were still above their initial weight, indicating that swelling still exceeded dissolution. Application of C30, C50 and HAcP as implant materials seems interesting where initial stabilization through bone bonding is needed or where the linear release of constituents is a requirement. HAcP has the advantage that the HA coating acts as a hydrolysis barrier and consequently delays the degradation of PLLA in vitro.     

Excessive infant crying: a controlled study of mothers helping mothers

OBJECTIVE: To determine the efficacy of behavioral management counseling in the treatment of persistent, excessive infant crying (> 3 hours per day). DESIGN: Two treatments, one no treatment control group. Infants were group-matched according to baseline fuss/cry levels, sociodemographic, and infant variables. Treatments were carried out sequentially by the same counselors. SETTING: Telephone counseling by volunteers (mothers) of CRY-SIS, a national support group for the parents of crying infants. PATIENTS AND INTERVENTIONS: Sequential sample of 27 mother-infant pairs receiving treatment 1 (Tr1, empathy: talking through the problem), 21 receiving treatment 2 (Tr2, behavioral management: specific care taking suggestions) and 44 receiving no treatment (C, controls). Infants were between 1 to 5 months of age. MEASUREMENTS AND RESULTS: Mother-infant pairs had a pretreatment baseline assessment and a posttreatment follow-up (3 months after baseline) using 1-week diaries. Total fuss/cry duration reduced significantly more in the behavioral management group (by 51%) than the empathy group (37%) or the control group (35%). This was mainly due to significantly reduced evening fussing/crying in Tr2 (67%) compared with Tr1 (45%) and C (42%). No differences in total number of fuss/cry bouts/day were found. However, the number of fuss/cry bouts reduced significantly more in the evening in Tr2 (by 55%) compared with Tr1 (27%) and C (32%). Behavioral management mothers evaluated the same counselors as more sympathetic, knowledgeable, and understanding. Tr2 was also perceived by mothers to have helped them more in reducing the crying problem, coping with the infant, and improving the relationship with their infant than Tr1. No effects of treatment on infant difficult temperament were found. CONCLUSIONS: Behavioral management was more effective in reducing fussing/crying than spending time with the mother talking through the problem or just waiting for spontaneous remission. Treatment by suitably but briefly trained lay counselors is an inexpensive and successful treatment option.     

A histological evaluation of the effect of hydroxyapatite coating on interfacial response

The effect of hydroxyapatite (HA) coating on cortical bone apposition around press-fit inserted implants and implants surrounded by a gap was investigated. Uncoated and HA-coated titanium implants were inserted in burr holes with three different diameters in the tibia of rabbits. Implantation time was four months. The histological evaluation demonstrated that after four months implantation the interfacial bone reaction appeared to be identical for HA-coated and non-coated implants with various degrees of surgical fit. Although after four months the interface showed the same response, there still might be an initial advantage of the HA-interface with bony tissue.     

In vivo dissolution behavior of various RF magnetron sputtered Ca-P coatings

Apolipoprotein E (apoE), a protein produced by glial cells, is responsible for maintenance of the structural integrity of the microtubules within the axon of the neuron. The gene associated with apolipoprotein E, APOE, influences the construction and regeneration of the microtubules in an APOE allele-specific manner: APOE 2/2 may be neuroprotective, whereas APOE 4/4 may be neurodestructive. Thus, APOE appears to be one genetic factor that modifies the brain's response to insult, and therefore may modify the severity of neuropsychologic deficits. This article presents an overview of the genetic relation between APOE and neuropsychological function in Alzheimer disease and proposes a relation between APOE and recovery after head injury.     

The influence of discharge power and heat treatment on calcium phosphate coatings prepared by RF magnetron sputtering deposition

Ca–P coatings with different Ca/P ratio and composition were successfully prepared by RF magnetron sputtering deposition. The Ca/P ratio, phase composition, structure and morphological properties were characterized by XRD, FTIR, EDS and SEM analyses. All the as-sputtered coatings were amorphous and after IR-irradiation the coatings altered into a crystalline phase. The obtained coatings had a Ca/P ratio that varied from 0.55 to 2.10 and different phase compositions or mixtures of apatite, beta-pyrophosphate and beta-tricalciumphosphate structures were formed. Evidently, the phase compositions of the sputtered coatings are determined not only by the discharge power ratio of the hydroxylapatite and calcium pyrophosphate targets but also by the annealing temperature.     

A model for thermal Marangoni drying

The process of thermal Marangoni drying is considered, which has been recently proposed for use in semiconductor production. The process allows ultraclean drying of semiconductor wafer surfaces at the end of a sequence of wet operations. A theoretical model is presented, which incorporates the movement of a thin liquid film on the semiconductor surface, heat exchange between the semiconductor and outer medium, and the water flow below the meniscus. In the frame of this model, the problem is solved using a combination of lubrication approximation, one-dimensional heat transfer analysis, and spectral-element solution of the two-dimensional Stokes equations. Several examples are given to show how the model can be used to evaluate the efficiency of drying.     

Bone healing capacity of titanium plasma-sprayed and hydroxylapatite-coated oral implants

The authors report preliminary results of Brief Supportive Psychotherapy (BSP) in the Beth Israel Brief Psychotherapy Program for a sample with primarily Cluster C Axis II disorders. This study compares 24 patients treated with BSP with 25 patients treated with Short-Term Dynamic Psychotherapy (STDP). STDP was chosen because its confrontational methods contrast dramatically to BSP, which emphasizes building self-esteem, reducing anxiety, and enhancing coping mechanisms. Videotaped therapies were based on manualized 40-session protocols. Similar degrees of improvement were seen in BSP and STDP at termination and at 6-month follow-up. A study of therapeutic alliance in BSP showed stable and high levels of alliance in good-outcome cases and more variability in poor-outcome cases. These preliminary findings are consistent with other studies and suggest supportive psychotherapy may be effective for many patients, leading to significant and lasting change.     

Studies on the thermal spraying of apatite bioceramics

Hydroxylapatite (HA) coatings on metal substrates have been investigated for many years. These coatings have proved to be compatible with bone. The degree of crystallinity of HA changed, and sometimes dissociation was observed with respect to the plasma spray process. However, the plasma spray process hardly altered the crystallographic structure, with only line broadening visible. Thein vitro solubility is dependent on the degree of crystallinity of the coating. Tensile strength measurements on the strength of the coating-substrate interface using various adhesives revealed a significant difference between epoxy resin and methacrylate. The failure mode of this tensile test was dependent on the coating thickness and surface texture (polished versus nonpolished). In animal studies, the fixation of hydroxylapatite plasma- spray coated cylinders as well as noncoated Ti- 6A1- 4V cylinders (Ti) in cortical bone was evaluated using pushout tests. It appeared that HA- coated implants showed higher push- out strengths in the first months than the titanium implants, because of the earlier bone formation against the HA coating.