Structure and function of the blood–brain barrier

Neural signalling within the central nervous system (CNS) requires a highly controlled microenvironment. Cells at three key interfaces form barriers between the blood and the CNS: the blood–brain barrier (BBB), blood–CSF barrier and the arachnoid barrier. The BBB at the level of brain microvessel endothelium is the major site of blood–CNS exchange. The structure and function of the BBB is summarised, the physical barrier formed by the endothelial tight junctions, and the transport barrier resulting from membrane transporters and vesicular mechanisms. The roles of associated cells are outlined, especially the endfeet of astrocytic glial cells, and pericytes and microglia. The embryonic development of the BBB, and changes in pathology are described. The BBB is subject to short and long-term regulation, which may be disturbed in pathology. Any programme for drug discovery or delivery, to target or avoid the CNS, needs to consider the special features of the BBB.     

Blood loss and replacement in total hip arthroplasty: a multicenter study. The Preoperative Autologous Blood Donation Study Group

To determine blood loss, the number of transfusions, and the hemoglobin levels achieved in patients via transfusion in the course of total hip arthroplasty, 324 patient records from 1987 through 1989 were reviewed at three university and three community hospitals. Calculated blood loss was 3.2 +/- 1.3 units in primary procedures and 4.0 +/- 2.1 units in revision procedures (mean +/- SD). Of 777 red cell units transfused, 455 (59%) were autologous units. Transfused patients received 2.0 +/- 1.8 units for primary procedures and 2.9 +/- 2.3 units for revision procedures (mean +/- SD). The maximum number of units given to 95 percent of the transfused patients was 4 for primary procedures and 6 for revision procedures. The mean postoperative hemoglobin level after all transfusions was 103 to 110 g per L, regardless of patient age group of physical status, autologous donor status, or hospital. No difference in length of hospital stay was observed for patients less than 65 years old with hemoglobin concentrations of 80 to 139 g per L at discharge.     

A patient with the inability to maintain in vivo levels of bound cobalamin (Cbl) and manifestations of tissue deficiency of Cbl

A 39-year-old woman presented with mild anemia, glossitis, an increased MCV, a low serum cobalamin (Cbl) (vitamin B12), mild tissue deficiency of Cbl, but with neither malabsorption of Cbl, impaired intake, nor deficiency of or inactivity of transcobalamin II (TC II). Because of a persistently low holo-TC II (TC II carrying Cbl as the circulating complex of TC II-Cbl), much of the evaluation was focused on the patient's TC II. Her TC II promoted the uptake of Cbl, reacted with anti-TC II, and bound Cbl in vitro. A test dose of 200 micrograms of cyanocobalamin (CN-Cbl) i.m. increased her holo TC II to levels higher than those in healthy persons, but with a much more abrupt fall to a subnormal level. Two milligrams of CN-Cbl i.m. followed by 100 micrograms i.m. monthly failed to maintain normal amounts of circulating TC II-Cbl or to overcome the tissue deficiency of Cbl. One milligram i.m. weekly or daily p.o. corrected both. The low holo TC II was considered to be responsible for the clinical expression and may have been primary to the reduced amounts of total and holo R binder of Cbl in the circulation. This study of a newly recognized defect points out the need for circulating holo TC II, a rational use of pharmacologic amounts of Cbl, and a possible interrelationship between TC II and the R binder of Cbl.     

Chronic acalculous cholecystitis: difficulties in diagnosis

A review of 142 consecutive cholecystectomies done in an Army Community Hospital was carried out to evaluate the number of chronic acalculous gallbladders encountered and the means used to diagnose them. The study concluded that the percentage of chronic acalculous gallbladders was higher than is normally reported in the literature. Whether this represents a trend needs to be substantiated. Also, while no one test appeared superior to another, when coupled with a thorough history, a diagnosis was arrived at more readily. Furthermore, it appears that a profile could be developed to cull out patients more likely to be candidates for this entity.     

Treatment of leg ulcers with an allogeneic cultured-keratinocyte-collagen dressing

A living cellular allogeneic dressing made up of cultured keratinocytes adhering to a collagen film was used to treat 20 leg ulcers of various aetiologies in 16 patients. A reduction in pain was noted in 80% of cases, and promotion of granulation tissue in the ulcer bed in 70% of cases. In 10 patients, epithelialization of 71 +/- 29% of the ulcer was noted at Day 30.     

Total radical trapping antioxidant potential (TRAP) and exercise

The relationship between physical activity, physical fitness and total radical trapping antioxidant potential (TRAP) was examined in the Northern Ireland Health and Activity Survey. This was a cross-sectional population study (n = 1600) using a two-stage probability sample of the population. TRAP was calculated using the sum of the individual serum antioxidant concentrations (urate, protein thiols, ascorbate, alpha tocopherol and bilirubin) multiplied by their respective stoichiometric values. Physical fitness was determined by estimation of VO2max by extrapolation from submaximal oxygen uptake, and physical activity was recorded by computer-assisted interview. Mean serum TRAP concentrations were significantly higher in males (653 +/- 8.2 mumol/l, mean +/- SEM) compared to females (564 +/- 8.0 mumol/l) (p < 0.0001). Both male and female smokers had significantly lower TRAP values than non-smokers (males p < 0.0001, females p = 0.02). In females, there was a positive relationship of TRAP with age (p < 0.001) and body mass index (p < 0.001) but a negative relationship with physical fitness (p < 0.05). The known beneficial effects of exercise and activity do not appear to be directly mediated through increased antioxidant status.      

In Vivo Feedback Predicts Parent Behavior Change in the Attachment and Biobehavioral Catch-up Intervention

Understanding mechanisms and active ingredients of intervention is critical to training clinicians, particularly when interventions are transported from laboratories to communities. One promising active ingredient of parenting programs is clinicians’ in vivo feedback regarding parent–child interactions. The present study examined whether a form of in vivo feedback, in the moment commenting, predicted treatment retention and parent behavior change when the Attachment and Biobehavioral Catch-up (ABC) intervention was implemented in a community setting. Observational data were collected from 78 parent–child dyads (96% mothers; M age = 29 years; 81% minority; infants’ M age = 12 months; 90% minority) across 640 sessions conducted by 9 clinicians (100% female, M age = 39; 67% minority) in Hawaii. Parental behavior was assessed with a semistructured play task before and after intervention. Clinicians’ in-the-moment feedback to parents was assessed from intervention session videos. Clinicians’ frequency and quality of in-the-moment feedback predicted change in parental intrusiveness and sensitivity at posttreatment. Frequency of in-the-moment feedback also predicted likelihood of retention. Hierarchical linear modeling demonstrated strong support for these associations at the between-clinician level, and limited additional support at the within-clinician (i.e., between-case) level. Thus, a hypothesized active ingredient of treatment, in-the-moment feedback, predicted community-based ABC outcomes. The results complement lab-based evidence to suggest that in vivo feedback may be a mechanism of change in parenting interventions. Helping clinicians to provide frequent, high-quality in vivo feedback may improve parenting program outcomes in community settings.