Mechanical and Cellular Changes During Compaction of a Collagen-Sponge-Based Corneal Stromal Equivalent

The need for corneas suitable for transplantation, combined with the decreasing supply, has fueled interest in the development of a corneal replacement. In this study, a collagen-sponge-based stromal equivalent, consisting of human corneal fibroblasts cultured on a type I collagen sponge, was maintained in culture for up to 21 days and characterized with respect to mechanical properties and cellular behavior. The Young's modulus of the stromal equivalent varied from 95 to 370 Pa, and its permeability varied from 5.3 x 10(-8) - 4.2 x 10(-7) m4 N(-1) s(-1). The greatest changes occurred during the first few days in culture, but the mechanical properties continued to change during the entire 21 days. Cell traction stress, determined from sponge compaction and DNA count, decreased during the compaction process with the maximum traction value the initial value of 6.6 +/- 2.9 x 10(-3) Pacm3 cell(-1). Microarray data showed that the expression level of fibronectin, decorin sulfate, collagenase, and gelatinase A was upregulated at day 14 in the sponge. This suggested that the repair fibroblast phenotype was being expressed by the fibroblasts. Additional analysis suggested that a subpopulation of cells expressed the myofibroblast phenotype.     

Estimating the relative frequency of leukodystrophies and recommendations for carrier screening in the era of next‐generation sequencing

Leukodystrophies are a heterogeneous group of heritable disorders characterized by abnormal brain white matter signal on magnetic resonance imaging (MRI) and primary involvement of the cellular components of myelin. Previous estimates suggest the incidence of leukodystrophies as a whole to be 1 in 7,000 individuals, however the frequency of specific diagnoses relative to others has not been described. Next generation sequencing approaches offer the opportunity to redefine our understanding of the relative frequency of different leukodystrophies. We assessed the relative frequency of all 30 leukodystrophies (associated with 55 genes) in more than 49,000 exomes. We identified a relatively high frequency of disorders previously thought of as very rare, including Aicardi Goutières Syndrome, TUBB4A‐related leukodystrophy, Peroxisomal biogenesis disorders, POLR3‐related Leukodystrophy, Vanishing White Matter, and Pelizaeus‐Merzbacher Disease. Despite the relative frequency of these conditions, carrier‐screening laboratories regularly test only 20 of the 55 leukodystrophy‐related genes, and do not test at all, or test only one or a few, genes for some of the higher frequency disorders. Relative frequency of leukodystrophies previously considered very rare suggests these disorders may benefit from expanded carrier screening.     

Pharmacokinetics of rhuMAb CD18, a Recombinant Humanised Monoclonal Antibody Fragment to CD18, in Normal Healthy Human Volunteers

Background and Objectives: Leucocyte β2 integrin adhesion receptors are hypothesised as a therapeutic target to modify immune responses to ischaemia-reperfusion injury that may be detrimental to recovery in a variety of disease states. Two phase I studies were designed to evaluate the pharmacokinetics, immunogenicity and safety of rhuMAb CD18, ahumanised monoclonal antibody F(ab’)₂ fragment to the CD18 receptor, in normal healthy human volunteers. Study Design and Methods: The first study evaluated six escalating doses of rhuMAb CD18 (0.06, 0.12, 0.25, 0.5, 1.0, 2.0 mg/kg) in 36 subjects given two intravenous (IV) bolus injections 12 hours apart. In the second study, 16 subjects received IV doses of 1.0 and 2.0 mg/kg as a single dose or as two doses given 12 hours apart. Study endpoints were rhuMAb CD18 serum pharmacokinetics, change in white blood cell (WBC) count, and safety and tolerability. The two studies enrolled a total of 53 subjects. Results: Serum concentration-time profiles demonstrated a monophasic decline and were best characterised by a one-compartment pharmacokinetic model. At the doses administered, the volume of distribution approximated the serum volume (range of means: 42 to 58 ml/kg). The serum clearance decreased with increasing dose until becoming consistent at doses of 0.5 to 2.0 mg/kg (range of means: 3.1 to 5.0 ml/h/kg). At doses of 0.5 to 2.0 mg/kg, the mean elimination half-life ranged from 7.0 to 9.6 hours. WBC counts increased at doses of above 0.06 mg/kg, returning to within 20% of predose values by day 7. Antibodies to rhuMAb CD18 were not detected at day 28. Mild-to-moderate adverse events were observed in both the placebo and treated groups, and were limited to flu-like symptoms. One subject experienced a serious adverse event (febrile reaction) and recovered with minimal intervention. There was no evidence of an increase in infection in subjects who received rhuMAb CD18. Conclusions: Upon IV bolus administration, rhuMAb CD18 serum concentration-time data fit a one-compartment pharmacokinetic model. At doses of 0.5 to 2.0 mg/kg, the pharmacokinetics were linear and the half-life ranged from 7.0 to 9.6 hours with a volume of distribution that approximated the serum volume. No antibodies to rhuMAb CD18 were detected. A transient, dose-dependent increase in the WBC count was observed, consistent with the expected effect of rhuMAb CD18 on leucocyte demargination. No increase in infection was observed. rhuMAb CD18 administered by IV bolus was well tolerated, with the exception of one febrile reaction.     

Immunological adjuvants: desirable properties and side-effects

Adjuvants can be used with recombinant antigens to elicit cell-mediated immunity and antibodies of protective isotypes (IgG2a in the mouse and IgG1 in primates). Adjuvants should not produce reactions at injection sites, be pyrogenic or induce anterior uveitis or arthritis. Among 130 analogs of muramyl dipeptides tested, N-acetylmuramyl-L-threonyl-D-isoglutamine showed the greatest separation of potency as an adjuvant from potency in the production of side-effects. A stable emulsion of squalane and the Pluronic polymer L-121 provides a versatile vehicle for targeting of antigens to antigen-presenting cells. The combination of this emulsion with the threonyl analog of MDP is termed Syntex Adjuvant Formulation. This formulation increases the efficacy of influenza, hepatitis B virus, herpes simplex virus, lentivirus and tumor vaccines in experimental animals.     

Viral load,CD4 percentage,and delayed-type hypersensitivity in subjects receiving the HIY-1 Immunogen and antiviral drug therapy

Two trials of subjects inoculated with the inactivated, gp120-depleted HIV-1 Immunogen are reported. In one study, in which 19 subjects received ZDV and 8 subjects received ddI, treatment with the HIV-1 Immunogen did not affect the pharmacokinetic parameters of the antiviral drugs. In another study, 65 subjects who were previously immunized with the HIV-1 Immunogen over a mean period of 4.0 years (range, 1.2–5.4 years) received inoculations at 0 and 6 months. At some point during this 48-week study, 72% of the subjects (47/65) were receiving antiviral drug therapy. The HIV-1 DNA load in CD4 cells and CD4 percentage were found to be stable over the 48-week period. Delayed-type hypersensitivity to HIV-1 antigens increased after two inoculations with the HIV-1 Immunogen. In these two trials, no serious treatment-related adverse events were documented in the subjects. The two studies presented herein are the first to suggest that an immune-based therapy such as the HIV-1 Immunogen can be combined safely with antiviral drugs, supporting further study to evaluate the clinical utility of this approach.     

Energy Balance,Eating Disorder Risk,and Pathogenic Behaviors Among Athletic Trainers

ContextResearch exists on energy balances (EBs) and eating disorder (ED) risks in physically active populations and occupations by settings, but the EB and ED risk in athletic trainers (ATs) have not been investigated.ObjectiveTo assess ATs'' energy needs, including the macronutrient profile, and examine ED risk and pathogenic behavioral differences between sexes (men, women) and job statuses (part time or full time) and among settings (college or university, high school, nontraditional).DesignCross-sectional study.SettingFree living in job settings.Patients or Other ParticipantsAthletic trainers (n = 46; male part-time graduate assistant ATs = 12, male full-time ATs = 11, female part-time graduate assistant ATs = 11, female full-time ATs = 12) in the southeastern United States.Main Outcome Measure(s)Anthropometric measures (sex, age, height, weight, body composition), demographic characteristics (job status [full- or part-time AT], job setting [college/university, high school, nontraditional], years of AT experience, exercise background, alcohol use), resting metabolic rate, energy intake (EI), total daily energy expenditure (TDEE), EB, exercise energy expenditure, macronutrients (carbohydrates, protein, fats), the Eating Disorder Inventory-3, and the Eating Disorder Inventory-3 Symptom Checklist.ResultsThe majority of participants (84.8%, n = 39) had an ED risk, with 26.1% (n = 12) engaging in at least 1 pathogenic behavior, 50% (n = 23) in 2 pathogenic behaviors, and 10.8% (n = 5) in >2 pathogenic behaviors. Also, 82.6% of ATs (n = 38) presented in negative EB (EI < TDEE). Differences were found in resting metabolic rate for sex and job status (F_1,45 = 16.48, P = .001), EI (F_1,45 = 12.01, P = .001), TDEE (F_1,45 = 40.36, P < .001), and exercise energy expenditure (F_1,38 = 5.353, P = .026). No differences were present in EB for sex and job status (F_1,45 = 1.751, P = .193); χ² analysis revealed no significant relationship between ATs'' sex and EB (= 0.0, P = 1.00) and job status and EB ( = 2.42, P = .120). No significant relationship existed between Daily Reference Intakes recommendations for all macronutrients and sex or job status.ConclusionsThese athletic trainers experienced negative EB, similar to other professionals in high-demand occupations. Regardless of sex or job status, ATs had a high ED risk and participated in unhealthy pathogenic behaviors. The physical and mental concerns associated with these findings indicate a need for interventions targeted at ATs'' health behaviors.     

Skeletal differences between black and white men and their relevance to body composition estimates

Skeletal differences exist between closely matched Black and White women, although it is unknown if similar differences also exist between Black and White men after controlling for age, body weight, and stature. The aim of this study was twofold: to test the hypothesis that Black men have greater bone mass, higher bone mineral density, and longer limbs compared to White men of similar age, weight, and height; and second, to establish if ethnic variation in skeletal characteristics has an impact on the models upon which three widely used methods for estimating total body fat are based. Twenty-four healthy Black men were matched by age (±5 years), height (±3 cm), and weight (±2 kg) to 24 healthy White men. Skeletal characteristics and body composition were studied using anatomical and compartment estimates derived by anthropometry, ³H₂O dilution, hydrodensitometry, whole-body ⁴⁰K counting, and dual photon systems. Black men had greater bone mineral mass (P = 0.007), higher bone density (P = 0.054), longer femurs (P = 0.002), longer anthropometric arm and thigh lengths (P = 0.001 and P = 0.002, respectively), lower spine to femur ratio (P = 0.004), and similar spine length (P = 0.271) compared to White men. Total body fat and fat-free body mass (FFM) were estimated in the men using a four-compartment model. Black and White men had similar total body fat, K (TBK), water (TBW), and FFM. Density of FFM and TBK/FFM were also similar between Black and White men, suggesting that current two-compartment hydrodensitometry and TBK models for estimating fat may not require adjustments for ethnicity. The TBW/FFM ratio, which is the main assumed steady-state relation for the two-compartment TBW method of estimating fat, was modestly increased (P = 0.05) in Black men (x? ± SD, 0.744 ± 0.018) compared to White men (0.732 ± 0.021). These results confirm that Black and White men differ significantly in some skeletal characteristics and these differences have implications in the study of both osteoporosis and human body composition. © 1994 Wiley-Liss, Inc.