Cranial sutures require tissue interactions with dura mater to resist osseous obliteration in vitro

A chemically defined serum-free medium, which supports the development of bones and fibrous tissues of rat calvaria from nonmineralized mesenchymal precursor tissues, was employed to investigate tissue interactions between the dura matter and overlying tissues. Fetal calvarial rudiments from stages prior to bone and suture morphogenesis (fetal days 19 and 20) and neonatal calvarial rudiments with formed sutures (day 1) were cultured with and without associated dura mater. Removal of calvaria for in vitro culture allowed the examination of suture morphogenesis in the absence of tensional forces exerted on the sutures via fiber tracts in the dura mater originating in the cranial base. Ossification of frontal and parietal bones proceeded in a fashion comparable to development in vivo, but the cranial (coronal) sutures--primary sites for subsequent skull growth--were obliterated by osseous tissue union in the absence of dura mater. Bony fusion did not occur when rudiments were cocultured with dura mater on the opposite sides of 0.45 microns polycarbonate transwell filters, suggesting that the influence of dura mater on sutural obliteration was mediated by soluble factors rather than cell-cell or cell-matrix interactions. These results indicate that cell signaling mechanisms rather than biomechanical tensional forces are required for morphogenesis of the calvaria.

Squamous cell carcinoma growth in irradiated tissue: a murine model for quantitative assessment of treatment

Locoregional recurrent and distant metastases from squamous cell carcinomas, despite multimodality therapy, remain troublesome clinical realities. Discrepancies in success rates of various surgery and radiation treatment regimens dealing with these problems are confusing to the clinician attempting to recommend the most beneficial treatments. There is a need for an experimental model to assess therapeutic effectiveness quantitatively from which guidelines for developing clinical trials may be suggested. In this study, we provide such a model. We injected DBA-2 mice with defined numbers of KLN-205 squamous carcinoma cells to obtain baseline growth characteristics; 216 animals had no previous irradiation. The remaining 131 received 30 Gy irradiation to the right leg 50 days before injection of the tumor cells. Tumor incidence, growth and number, and location of tumor metastasis were determined in both previously irradiated and nonirradiated groups. The data demonstrate a growth-retardant effect on tumor groups by the previous irradiation (tumor bed effect). The data also show that the incidence of hematogenously spread metastases was more frequent in mice in which tumors developed in previously irradiated tissue than in mice with tumors in nonirradiated tissue.

An immunization update for primary health care providers

Despite notoriously low immunization levels among children in the United States in recent decades, provisional statistics for 1994 are encouraging. This may be related to several recent governmental initiatives that have focused attention on immunizations. A new vaccination schedule, effective January 1995, marked major progress in the clarification of immunization guidelines. This article discusses current recommendations for both pediatric and adult immunizations. The text includes information about the current incidence of communicable diseases, recent governmental policies affecting availability of vaccines, standards for immunization practice, and guidelines for storage and handling of vaccines. A table outlines recommended vaccines in the following areas: 1) vaccine antigen, dose, and route, 2) routine schedule for administration, 3) precautions and contraindications, 4) adverse reactions, 5) serious adverse reactions, and 6) education.

Case management and preventive services among infants from low-income families

To determine the impact of an experimental approach to case management on use of child health clinic and immunization services, a nonequivalent control group with covariate measures design was employed in a sample of 98 infants from low-income families. The innovative pattern of care featured continuity of care; a single public health nurse (PHN) provided child health care to an infant by integrating case management and preventive services. In contrast, the customary pattern of child health care was characterized by fragmentation of services. Case management was segregated from preventive services, and multiple PHNs delivered care to an infant. As predicted, experimental-group infants (44%) were more likely to achieve adequate child health clinic services than control-group infants (8%) (p < 0.001). Moreover, the cost-effectiveness (C/E) ratio (dollar cost per effective intervention) for adequate child health clinic visits in continuous care ($523) was one-fifth of that in fragmented care ($2,900). The C/E ratio related to adequate immunization was 8% less in continuous care ($359) than in the fragmented approach ($386), although the difference in rates of adequate immunization was nonsignificant (experimental group, 64%; control group, 60%). These findings suggest that continuous PHN care with integrated case management is a more effective, cost-efficient approach to critical child preventive services than the customary, segregated case-management approach.

Skull base expansion: craniofacial effects

In order to determine what effect the anterior cranial base has on the developing craniofacial skeleton, mechanical expansion of the growth of one segment of the anterior cranial base was performed. New Zealand white rabbits were used for this study. A sham-treated group (n = 16) underwent implantation of dental amalgam markers to either side of the frontonasal, coronal, and lambdoid sutures at 9 days of age to serve as markers of vault growth. The experimental group (n = 7) underwent the same marker placement at 9 days of age, but, in addition, at 30 days of age these animals underwent placement of a mechanical spring, unilaterally, at the frontosphenoid suture. A second control group (n = 8) underwent the same exposure of the frontosphenoid suture, but the spring was laid only on the surface of the bone. All animals were followed by radiographic cephalometry at 9, 30, 60, and 90 days of age. The experimental group demonstrated statistically significant expansion of the cranial base and ipsilateral coronal suture. The midface skeletal dimensions were unchanged by spring distraction of the cranial base. These findings indicate that cranial base sutural growth can be manipulated mechanically and that growth changes can be attained secondarily in the cranial vault skeleton.

Isolation and characterization of a membrane-attack-complex-inhibiting protein present in human serum and other biological fluids

We have previously reported the isolation of a membrane-attack-complex-inhibiting protein (MIP) from human erythrocyte membranes [Watts, Patel & Morgan (1987) Complement 4, 236] and the production of polyclonal antibodies to this protein. Here we report the identification in plasma, urine, saliva and cerebrospinal fluid of a protein immunochemically identical with the membrane-derived MIP. The protein has been isolated from plasma by immunoaffinity chromatography on an anti-(erythrocyte MIP)-Sepharose column and shown by SDS/polyacrylamide-gel electrophoresis to be of similar molecular mass to the erythrocyte protein (55 kDa non-reduced and 65 kDa under reducing conditions). Monoclonal antibodies have been raised against plasma MIP and used to establish a two-site enzyme-linked immunoadsorbent assay, enabling quantification of MIP in plasma, urine and cerebrospinal fluid. Plasma MIP, though not able to incorporate spontaneously into membranes, was deposited on heterologous and homologous erythrocyte membranes during complement activation in a C8-dependent manner. Depletion of MIP from plasma resulted in enhancement of the lytic capacity of the plasma on heterologous erythrocytes.