Effects of glucocorticoids on the rabbit carotid body

Weekly intramuscular injections of slow-release, depot methyl prednisolone to 15 adult Dutch rabbits did not bring about an increase in the volume of their carotid bodies. However, they caused swelling of chief cells with discrete areas of pallor in the cytoplasm. Factors responsible for these changes appear to be increased storage of catecholamines and an increased number of swollen mitochondria.     

Distribution of alleles of the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism in familial spina bifida

Spina bifida cystica (SB) is one of the most common and disabling of birth defects. Folic acid supplementation in mothers during the periconceptional period has been shown to prevent more than 70% of neural tube defects (NTD) including SB. However, the mechanism is unknown. We tested a series of multicase SB families in which 224 individuals were genotyped and a group of 215 unrelated unaffected (external) control individuals for association of SB with the T allele of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism that produces a heat-labile enzyme protein. The data were analyzed using first the transmission/disequilibrium test (TDT) and second a modified case-control study design with Monte Carlo sampling methods. No association of SB with the MTHFR T allele was found by either method. Presently, association between SB and the T allele has been found in four studies, a Dutch study, an Irish study, a North American study, and an Italian study. But no association was found in four other studies, a British study, a French study, a Turkish study, and a German study. A California population-based study found only modestly increased risk of SB with this allele that was not significant at the P < 0.05 level. The present study finds no evidence of the association. Only one other study, the German study, has used TDT analysis. The present study is the first to use a modified case-control study design with Monte Carlo sampling methods to test this association. Thus, it appears that the MTHFR T allele is a risk factor for SB in some populations but not others. Major genetic risk factors for folate-related SB remain to be found.     

Cognate CD4(+) T cell licensing of dendritic cells in CD8(+) T cell immunity

Several studies have indicated that CD8(+) T cells require CD4(+) T cell help for memory formation. Evidence suggests that such help can be antigen independent, challenging whether the 'licensing' of dendritic cells (DCs) by CD4(+) T cells is ever required for cytotoxic T lymphocyte (CTL) responses. We show here that help is essential for the generation of CTL immunity to herpes simplex virus 1 and that CD4(+) T cells mediate help in a cognate, antigen-specific way. We provide direct in vivo evidence for DC licensing by helper T cells and show that licensing is rapid and essential for the formation of effector and memory CTLs. In situations in which DCs are poorly licensed by pathogen-derived signals, our findings suggest that CTL immunity may be heavily dependent on cognate DC licensing.     

The thickness of the alveolar capillary wall in guinea-pigs at high and low altitude

The thickness of the alveolar-capillary wall was measured in the lungs of seven guinea-pigs born and living at La Raya, in the Peruvian Andes, at an altitude of 4200 m and in seven sea-level representatives of the same species. This was achieved by carrying out morphometric studies on electron micrographs to obtain the so-called arithmetic and harmonic mean thicknesses. The arithmetic mean thickness was always the larger, this being due to the greater emphasis which the technique employed places on the copious amounts of connective tissue in the interstitial space of the alveolar capillary wall in this species. These thicker portions of the alveolar wall are not concerned with gaseous diffusion. The harmonic mean thickness probably gives a more physiologically realistic estimate of the magnitude of the diffusion barrier to oxygen. This proved to be smaller in the animals from high altitude and may facilitate diffusion of oxygen from alveolar spaces to blood, thus making less steep the "oxygen cascade" from inspired air to mitochondria.     

Correction to: Patterns of School Victimization and Problem Behaviors: Longitudinal Associations with Socioeconomic Well-Being and Criminal Justice Involvement

Child & Youth Care Forum -     

A statewide survey of general practitioners in NSW, Australia, about immunisation and strategies to increase childhood immunisation rates

A statewide survey was conducted to ascertain GPs' views in New South Wales (NSW), Australia, about the potential usefulness of strategies to increase immunisation rates and to facilitate providing childhood immunisation in their practice. The survey also explored the usefulness of information sources about immunisation. From September 1997-January 1998, a cross-sectional study using a four page self-administered questionnaire was undertaken. Four hundred GPs practising in NSW, Australia were randomly selected and 343 were eligible to participate. Of these, 281 returned a completed questionnaire (82% response rate). Ninety-one percent and 88% of GPs, respectively, agreed that television campaigns or registering children with the national Australian Childhood Immunisation Register (ACIR) were likely to increase immunisation rates. Sixty-two percent of respondents considered that the media created unwarranted parental concern about immunisation. GPs most commonly rated availability of an ACIR list of children overdue for immunisation, better parent educational material and better access to vaccines as strategies which would make immunisation easier. Sixty percent of respondents felt that increased GP payments would be successful in increasing immunisation rates. Only 51% indicated that they had used the "Australian Immunisation Procedures Handbook 6th edition" (a national clinical practice guideline) in the previous month. This study identified GP support for many initiatives aimed at increasing immunisation rates in Australia although GPs were sceptical about the benefits of some programmes. Studies to monitor the impact of GP incentives on immunisation rates in populations and individual practices are underway. These will be useful in determining whether GPs' opinions found in our study correlate with practice in this regard.     

Training by Satellite: Planning and Evaluating a Video Conference for Injury Prevention Practitioners

A non-experimental design was employed to conduct both a process and impact evaluation of a video conference for injury control specialists and other community members. The video conference was designed to teach participants how to conceptualize, develop, and implement community-based injury and violence prevention programs. The six-hour event was broadcast to 120 sites all across the United States and had a total of 1270 participants. The video conference format included a panel of injury control specialists and a moderator, video and audio clips that were shown throughout the program, on and off screen activities for participants, and an opportunity for participants to ask questions of the panel. Three groups were included in the evaluation sample: participants; site facilitators; and stakeholders; which included the planning committee members, conference speakers, moderator, and audiovisual personnel. Evaluation data were collected by telephone and in-person interviews, focus groups, and surveys completed at all the viewing sites. Results showed that there was high satisfaction among the participants and that the program should be continued as a series of video conferences with a changing content. There was lower satisfaction with the online activities, applicability of material to their work, and the opportunity with to network with others and to participate in discussion. Recommendations made for improving future programs include shortening the video conference program, focusing on specific issues within injury and violence prevention, training the program presenters on the workings of the satellite video conference technology, use of video streaming, and using web-based forms for registration and evaluation.     

Semi-continuous perfusion system for delivering intermittent physiological pressure to regenerating cartilage

A semi-continuous compression/perfusion system has been custom made to allow the application of intermittent hydrostatic pressure, at physiological levels, to regenerating tissues over the long term. To test the system, isolated foal chondrocytes were seeded in resorbable polyglycolic acid meshes and cultured in the system for 5 weeks. The cell/polymer constructs were subjected to an intermittent hydrostatic pressure of 500 psi and were fed semi-continuously. Assays of the resulting tissue constructs indicate that the reactor supports cartilage development and that physiological intermittent compression enhances the production of extracellular matrix by the chondrocytes. The concentrations of sulfated glycosaminoglycan were found to be at least twice as high as those in control (unpressurized) samples. A correlation between the sulfated glycosaminoglycan content and the compressive modulus in pressurized, but not control, samples suggests that physiological intermittent pressurization not only enhances the production of extracellular matrix but may also influence matrix organization resulting in a stronger construct.