What Parents of Children Born with a Cleft Lip and/or Palate Want to Know About the Care for their Child.

OBJECTIVE: Adequate health information that matches the needs of care recipients is a prerequisite for patient-centered care. To facilitate the provision of tailored and timely information, it isimportant to understand the information needs of parents of children and adolescents with cleft lip and/or palate (CL/P) themselves, and in addition they were asked how they experienced the provided care-related information. DESIGN: A cross-sectional study employing questionnaires and semi-structured interviews. SETTING: Participants were recruited from a cleft palate-craniofacial care unit in a major tertiary hospital in the Netherlands. PARTICIPANTS: Participants were parents or guardians of children with CL/P, and two adolescents with CLP. They were recruited through the outpatient clinic during multidisciplinary consultation or after clinical admission. RESULTS: In total, fifty-five questionnaires were completed by parents or guardians and eleven interviews were conducted with nine parents of children with CL/P and two adolescents with CL/P. In general, participants reported to be satisfied with provided information during hospital admission or multidisciplinary cleft team consultations (mean 8.0, scale 0-10). In addition, 25.5% (n = 14) indicated that information to prepare for hospital admission was lacking (eg, practical information). Thematic qualitative analysis yielded five main information needs: 1) Clear communication during the care process, 2) Overview of the care trajectory, 3) Specific care plan information, 4) Presentation of information and 5) Guidance and support. CONCLUSIONS: Our findings emphasize the importance of gaining insights into wishes and information needs from care recipients who can provide insights in their information needs. With these findings, information provision should be redesigned to improve and to foster the further transition to family-centered care.

Long-Term Changes in Free Nipple Graft Morphology and Patient-Reported Outcomes in Gender-Affirming Mastectomies.

BACKGROUND: After gender-affirming mastectomies with free nipple grafts, satisfaction with nipples tends to fall short behind chest outcomes. This might be related to changes in nipple areolar complex (NAC) dimensions over time. Therefore, the aim of this study is to establish the long-term changes in NAC morphology and compare these to cisgender male NAC outcomes. MATERIALS: An observational, cross-sectional study was performed. Data from two prospective cohorts were collected: (1) transgender men after a mastectomy with free nipple grafts and (2) cisgender men (reference sample). Demographics and 3-D images were collected for both groups. NAC measurements were performed on the 3-D images at 4 time points (7-, 30-, 90- and 365-days postoperative) in transgender men and once in cisgender men. Furthermore, the BODY-Q (nipple module) was administered postoperatively at 30-, 90- and 365-days in transgender men. RESULTS: In total, 67 transgender and 150 cisgender men were included. NAC width and height in trans men changed from 21.5 mm (±2.7) to 23.8 mm (±3.9, p<0.001) and 16.2 mm (±2.5) to 14.7 mm (±3.0, p=0.01) within a year, respectively. On average, the NACs increasingly rotated 21 degrees in the latero-caudal direction (p<0.001). The mean NAC width and height in cisgender men were 28.1 mm (±5) and 20.7 mm (±4), being significantly larger than in transgender men. Satisfaction for size, shape and flatness decreased significantly after postoperative day 30 (p=<0.05) in transgender men. CONCLUSIONS: Morphology of and satisfaction with the NACs in transgender men significantly changed over time. Understanding and incorporating these differences into pre-operative counseling and surgical planning might help increase patient satisfaction. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Within-patient randomized clinical trial comparing incisional negative-pressure wound therapy with suction drains in gender-affirming mastectomies.

BACKGROUND: Incisional negative-pressure wound therapy (iNPWT) is widely adopted by different disciplines for multiple indications. Questions about the most appropriate uses and value of iNPWT have been raised. METHODS: An open-label within-patient RCT was conducted in transgender men undergoing gender-affirming mastectomies. The objective was to determine the effect of iNPWT as a substitute for standard dressing and suction drains on wound healing complications. One chest side was randomized to receive the iNPWT intervention, and the other to standard dressing with suction drain. The primary endpoints were wound healing complications (haematoma, seroma, infection, and dehiscence) after three months. Additional outcomes were pain according to a numerical rating scale and patient satisfaction one week after surgery. RESULTS: Eighty-five patients were included, of whom 81 received both the iNPWT and standard treatment. Drain removal criteria were met within 24 h in 95 per cent of the patients. No significant decrease in wound healing complications was registered on the iNPWT side, but the seroma rate was significantly increased. In contrast, patients experienced both significantly less pain and increased comfort on the iNPWT side. No medical device-related adverse events were registered. CONCLUSION: Substituting short-term suction drains with iNPWT in gender-affirming mastectomies increased the seroma rates and did not decrease the amount of wound healing complications. Registration number: NTR7412 (Netherlands Trial Register).

Supermagnonic Propagation in Two-Dimensional Antiferromagnets.

We investigate the propagation of magnons after ultrashort perturbations of the exchange interaction in the prototype two-dimensional Heisenberg antiferromagnet. Using the recently proposed neural quantum states, we predict highly anisotropic spreading in space constrained by the symmetry of the perturbation. Interestingly, the propagation speed at the shortest length scale and timescale is up to 40% higher than the highest magnon velocity. We argue that the enhancement stems from extraordinary strong magnon-magnon interactions, suggesting new avenues for manipulating information transfer on ultrashort length scales and timescales.

Functional Outcomes and Urological Complications after Genital Gender Affirming Surgery with Urethral Lengthening in Transgender Men.

PURPOSE: We determined the urological complications and lower urinary tract function after genital gender affirming surgery with urethral lengthening in transgender men. MATERIALS AND METHODS: A single center, retrospective cohort study was performed from January 2013 to January 2018. Patient demographics, medical history, perioperative data, surgical and urological complications, and preoperative and postoperative urological outcomes were obtained. RESULTS: Of the 63 patients included in the study 8 (13%) underwent metoidioplasty and 55 (87%) phalloplasty, comprised of 27 (43%) free radial forearm flap, 19 (30%) anterolateral thigh flap and 9 (14%) superficial circumflex iliac artery perforator flap surgeries. In phalloplasty the types of urethral lengthening were tube-in-tube free radial forearm flap in 27 (49%), free radial forearm flap (second fasciocutaneous flap) in 18 (33%), superficial circumflex iliac artery perforator flap in 5 (9%) or labial in 5 (9%). Mean followup was 23 months (range 12 to 71). Stricture formation occurred in 35 (63%) phalloplasty and 5 (63%) metoidioplasty cases. Urethral fistula formation occurred in 15 (27%) phalloplasty and 4 (50%) metoidioplasty cases. Mean time to strictures and fistulas was approximately 3 months. Overall 46 (73%) patients needed revision surgery because of fistulas/strictures. After treatment 44 (70%) patients were able to void from the tip of the phallus. No clinically relevant differences in International Prostate Symptom Scores, frequency volume charts and uroflowmetry were found preoperatively vs postoperatively. CONCLUSIONS: Genital gender affirming surgery with urethral lengthening is a complex procedure with a high complication rate. After treating complications no clinically relevant differences in urological functioning were recorded. The majority of transgender men could void from the tip of the penis and showed favorable urological outcomes.

Short-term cost-effectiveness of one-stage implant-based breast reconstruction with an acellular dermal matrix versus two-stage expander-implant reconstruction from a multicentre randomized clinical trial.

BACKGROUND: Implant-based breast reconstruction (IBBR) is the most commonly performed reconstructive procedure and its economic impact is significant. This study aimed to analyse whether a direct one-stage IBBR with use of an acellular dermal matrix (ADM) is more cost-effective than two-stage (expander-implant) breast reconstruction. METHODS: The BRIOS (Breast Reconstruction In One Stage) study was an open-label multicentre RCT in which women scheduled for skin-sparing mastectomy and immediate IBBR were randomized between one-stage IBBR with ADM or two-stage IBBR. Duration of surgery and hospital stay, and visits for the primary surgery, unplanned and cosmetic procedures were recorded. Costs were estimated at an institutional level. Health status was assessed by means of the EuroQol Five Dimensions 5L questionnaire. RESULTS: Fifty-nine patients (91 breasts) underwent one-stage IBBR with ADM and 62 patients (92 breasts) two-stage IBBR. The mean(s.d.) duration of surgery in the one-stage group was significantly longer than that for two-stage IBBR for unilateral (2·52(0·55) versus 2·02(0·35) h; P < 0·001) and bilateral (4·03(1·00) versus 3·25(0·58) h; P = 0·017) reconstructions. Costs were higher for one-stage compared with two-stage IBBR for both unilateral (€12 448 (95 per cent c.i. 10 722 to 14 387) versus €9871 (9373 to 10 445) respectively; P = 0·025) and bilateral (€16 939 (14 887 to 19 360) versus €13 383 (12 414 to 14 669); P = 0·002) reconstructions. This was partly related to the use of relatively expensive ADM. There was no difference in postoperative health status between the groups. CONCLUSION: One-stage IBBR with ADM was associated with higher costs, but similar health status, compared with conventional two-stage IBBR. Registration number: NTR5446 ( http://www.trialregister.nl).

Predictors of complications after direct-to-implant breast reconstruction with an acellular dermal matrix from a multicentre randomized clinical trial.

BACKGROUND: In the multicentre randomized trial BRIOS (Breast Reconstruction In One Stage), direct-to-implant (DTI) breast reconstruction with an acellular dermal matrix (ADM) was associated with a markedly higher postoperative complication rate compared with two-stage tissue expander/implant breast reconstruction. This study aimed to identify factors that contribute to the occurrence of complications after DTI ADM-assisted breast reconstruction. METHODS: Data were obtained from the BRIOS study, including all patients treated with DTI ADM-assisted breast reconstruction. Logistic regression analyses were performed to identify factors predictive of postoperative complications. RESULTS: Fifty-nine patients (91 breasts) were included, of whom 27 (35 breasts) developed a surgical complication. Reoperations were performed in 29 breasts (32 per cent), with prosthesis removal in 22 (24 per cent). In multivariable analyses, mastectomy weight was associated with complications (odds ratio (OR) 1·94, 95 per cent c.i. 1·33 to 2·83), reoperations (OR 1·70, 1·12 to 2·59) and removal of the implant (OR 1·55, 1·11 to 2·17). Younger patients (OR 1·07, 1·01 to 1·13) and those who received adjuvant chemotherapy (OR 4·83, 1·15 to 20·24) more frequently required reoperation. In univariable analyses, adjuvant radiotherapy showed a trend towards more complications (OR 7·23, 0·75 to 69·95) and removal of the implant (OR 5·12, 0·76 to 34·44), without reaching statistical significance. CONCLUSION: Breast size appeared to be the most significant predictor of complications in DTI ADM-assisted breast reconstruction. The technique should preferably be performed in patients with small to moderate sized breasts. Registration number: NTR5446 ( http://www.trialregister.nl).

Nationwide study on open tibial fractures in the Netherlands: Incidence, demographics and level of hospital care.

OBJECTIVES: Open tibial fractures are relatively common injuries following traffic accidents. The vulnerability of the soft tissues surrounding the tibia increases the susceptibility to complications, including infection and nonunion. To minimize complications, a multidisciplinary, timely approach is crucial. To date, the Dutch incidence and level of hospital treatment remain unknown due to a lack of condition-specific nationwide registries. This study aimed to estimate the incidence and management of open tibial fractures in the Netherlands, providing essential information for public health policymaking and guideline development. METHODS: The 2018 and 2019 Dutch National Hospital Care Basic Registration data, provided by the Dutch Hospital Data Foundation, were utilized to identify all patients admitted to Dutch hospitals with tibial fractures. Incidence rates, patient demographics, primary diagnoses, fracture classification, level of hospital, and length of hospital stays were analyzed using descriptive statistics. RESULTS: 1,079 ICD-10 codes for closed and open tibial fractures were identified in patients that were admitted to a Dutch hospital. Thirty-four percent were classified as open tibial fractures, accounting for an estimated incidence rate of 1.1 per 100,000 person-years (95 % CI 0.97-1.12). When categorized by age, the calculated incidence rate was higher in males for all age categories up until the age of 70. Notably, the overall highest incidence rate was found for females aged 90 and above (6.6 per 100,000 person-years). Open tibial fractures were predominantly treated in general or top clinical hospitals (comprising 69 % of open all tibia fractures). Notably, the minority (31 %) presented at university medical centers, all Level-1 trauma centers, equipped with orthoplastic teams. CONCLUSION: This is the first study to report the nationwide incidence rate of open tibial fractures in the Netherlands; 34 % of tibial fractures were registered as open. Notably, a limited proportion of open tibial fractures underwent treatment within Level-1 trauma centers. Consequently, in the majority of cases, the implementation of an orthoplastic team approach was unattainable. This study underscores the need for more comprehensive data collection to assess and improve the current treatment landscape.

A usability evaluation of the perceived user friendliness, accessibility, and inclusiveness of a personalized digital care pathway tool.

OBJECTIVE: This study aimed to acquire insight into the perceived user friendliness, accessibility and inclusiveness of a personalized digital care pathway. MATERIALS & METHODS: Usability of the tool was tested in an experimental setting. Mixed methods data collection consisted of scenario-based eye tracking tests in a web- or mobile-based prototype of the tool, followed by a questionnaire assessing user friendliness (System Usability Scale; SUS) and a structured interview. Inclusiveness was assessed by subgroup comparisons based on language proficiency, age and education level. Via purposive sampling a heterogeneous population of users (N = 24) was recruited. Eye tracking was used to measure gaze behavior. RESULTS: Overall, participants were satisfied with the tool (scale 0-10, 7.5; SD = 1.29). User friendliness of the mobile version (68.3; SD = 21.6) was higher than the web version (50.9; SD = 17.3) measured by SUS score (0-100). With regard to accessibility, eye tracking scenarios showed that the menu bar was hard to find (17% mobile, 55% web). In all scenario's, information was found faster in the mobile version than the web version. Attention was easily drawn to images. Regarding inclusiveness of the tool, we found significantly longer completing time of the scenario tasks for low language proficiency (p-value = 0.029) and higher age subgroups (p-value = 0.049). Lower language proficiency scored a significant lower SUS score (p-value = 0.012). CONCLUSIONS: Overall, user friendliness and accessibility were positively evaluated. Assessment of inclusiveness emphasized the need for tailoring digital tools to those with low language proficiency and/or an older age. Co-creation of digital care tools with users is therefore important to match users' needs, make tools easily understandable and accessible to all users, and ultimately result in better uptake and impact.

Standards of Care for the Health of Transgender and Gender Diverse People, Version 8.

Background: Transgender healthcare is a rapidly evolving interdisciplinary field. In the last decade, there has been an unprecedented increase in the number and visibility of transgender and gender diverse (TGD) people seeking support and gender-affirming medical treatment in parallel with a significant rise in the scientific literature in this area. The World Professional Association for Transgender Health (WPATH) is an international, multidisciplinary, professional association whose mission is to promote evidence-based care, education, research, public policy, and respect in transgender health. One of the main functions of WPATH is to promote the highest standards of health care for TGD people through the Standards of Care (SOC). The SOC was initially developed in 1979 and the last version (SOC-7) was published in 2012. In view of the increasing scientific evidence, WPATH commissioned a new version of the Standards of Care, the SOC-8. Aim: The overall goal of SOC-8 is to provide health care professionals (HCPs) with clinical guidance to assist TGD people in accessing safe and effective pathways to achieving lasting personal comfort with their gendered selves with the aim of optimizing their overall physical health, psychological well-being, and self-fulfillment. Methods: The SOC-8 is based on the best available science and expert professional consensus in transgender health. International professionals and stakeholders were selected to serve on the SOC-8 committee. Recommendation statements were developed based on data derived from independent systematic literature reviews, where available, background reviews and expert opinions. Grading of recommendations was based on the available evidence supporting interventions, a discussion of risks and harms, as well as the feasibility and acceptability within different contexts and country settings. Results: A total of 18 chapters were developed as part of the SOC-8. They contain recommendations for health care professionals who provide care and treatment for TGD people. Each of the recommendations is followed by explanatory text with relevant references. General areas related to transgender health are covered in the chapters Terminology, Global Applicability, Population Estimates, and Education. The chapters developed for the diverse population of TGD people include Assessment of Adults, Adolescents, Children, Nonbinary, Eunuchs, and Intersex Individuals, and people living in Institutional Environments. Finally, the chapters related to gender-affirming treatment are Hormone Therapy, Surgery and Postoperative Care, Voice and Communication, Primary Care, Reproductive Health, Sexual Health, and Mental Health. Conclusions: The SOC-8 guidelines are intended to be flexible to meet the diverse health care needs of TGD people globally. While adaptable, they offer standards for promoting optimal health care and guidance for the treatment of people experiencing gender incongruence. As in all previous versions of the SOC, the criteria set forth in this document for gender-affirming medical interventions are clinical guidelines; individual health care professionals and programs may modify these in consultation with the TGD person.

The ideal location of the male nipple-areolar complex: A pinpointing algorithm.

Background: In the treatment of gender dysphoria, appropriate nipple-areola complex (NAC) positioning is essential for achieving a natural appearing male chest after subcutaneous mastectomy. An accurate predictive model for the ideal personalized position of the NAC is still lacking. The aim of this study is to determine the anthropometry of the male chest to create individualized guidelines for appropriate NAC positioning in the preoperative setting. Materials and methods: Cisgender male participants were recruited. Multiple chest measurements were manually recorded. Best subset regression using linear models was used to select predictors for the horizontal coordinate (nipple-nipple distance; NN) and vertical coordinate (sternal notch-nipple distance; SNN) of the NAC. Internal validation was assessed using bootstrapping. Furthermore, a cohort of transgender men who had received a mastectomy with replantation of nipples according to current practice was identified. Comparison testing between the algorithm and standard practice was performed to test the limitations of standard practice. Results: One hundred and fifty cis male participants were included (median age: 26, IQR: 22-34 years). Four predictors were found to predict NN (age, weight, chest circumference (CC), anterior-axillar fold to anterior-axillar fold (AUX-AUX)) and reads as follows: NN = 4.11 + 0.035*age + 0.041*weight + 0.093*CC + 0.140*AUX-AUX Two predictors were found to predict SNN (NN and weight), and reads as follows: SNN = 7.248 + 0.303*NN + 0.072*weight. Both models performed well (Bootstrapped R2: 0.63 (NN), 0.50 (SNN)) and outperformed previous models predicting NAC position. Ninety-six transgender men were eligible for evaluation of current practice and showed an average placement error of -0.9 cm for NN and +2.2 cm for SNN. Conclusion: The non-standardized approach of NAC repositioning results in a significant error of nipple placement. We suggest that the two predictive models for NN and SNN can be used to optimize NAC positioning on the masculinized chest wall.Supplemental data for this article is available online at https://doi.org/10.1080/26895269.2021.1884926.

The multilayered structure of the human corpus spongiosum.

PURPOSE: Urethral reconstruction is performed in patients with urethral strictures or for correction of congenital disorders. In the case of shortage of tissue, engineered tissue may enhance urethral reconstruction. As the corpus spongiosum (CS) is important in supporting the function of the urethra, tissue engineering of the urethra should be combined with reconstruction of a CS. For that purpose, detailed knowledge of the composition of the CS, more specifically its extracellular matrix (ECM) and vascularization is needed for scaffold design. The objective of this study is to analyze the microarchitecture of the CS through (immuno) histology and scanning electron microscopy (SEM). METHODS: The CS including the urethra of patients undergoing male-to-female genital confirming surgery was harvested. This CS was fixed and processed for either (immuno) histology or for SEM. RESULTS: Four layers could be distinguished in the CS; first a transition zone from urethra epithelium to a collagen rich layer, which was highly vascularized, followed by a second, elastin rich layer. The third layer was formed by veins, arteries and vascular spaces and the last layer showed the transition from this vascular rich region to the collagen rich tunica albuginea. In this layer collagen bundles intertwined with elastic fibres. In the CS different components of the ECM were visible and distinguishable. CONCLUSION: This study provides novel and detailed information on the microarchitecture of the CS and the distribution of vascularization, which is important for scaffold design in tissue engineering.

Refractory diversion neovaginitis in a sigmoid-colon-derived neovagina: clinical and histopathological considerations.

Colonic segments are being used as pedicled grafts in neovaginoplasty, a surgical procedure to (re)construct a (neo)vagina. A disadvantage of using colonic grafts is the potential occurrence of neovaginal complications due to diversion from the faecal stream. Here, we report a case of severe, refractory diversion colitis of the sigmoid neovagina, so-called 'diversion neovaginitis', in a 42-year-old woman with complete androgen insensitivity syndrome. Neovaginal biopsy specimens showed colonic-type mucosa with strong increase of lymphoplasmacellular infiltrate in the lamina propria, ulceration with fibrinoid deposition and some crypt irregularity. Endoscopy showed erythematous mucosa, superficial ulceration, mucus discharge and multiple pseudopolyp-like lesions. Local application of mesalazine foam enemas and sodium butyrate enemas initially gave symptom relief. However, this was a temporary effect, ultimately necessitating removal of the neovaginal construct. It is important that all patients are informed about neovaginal bowel complications, for example, diversion neovaginitis. Regular medical and endoscopic follow-up appears recommendable.

Surgery for extra-articular trismus: a systematic review.

The aim of this systematic review was to identify operations that are used to improve mouth opening in patients with extra-articular trismus (caused by cancer and its treatment, oral submucous fibrosis, or noma) and to find out if they work. We searched the electronic databases PubMed, Embase, Cinahl, and the Cochrane collaboration, and then systematically selected papers before we assessed their quality, extracted the data, and did a meta-analysis. We analysed 32 studies that included 651 patients, the median (IQR) size of which was 11 (7-26). The quality of the methods used and of reporting were relatively low. Median (IQR) duration of follow-up was 12 (8-22) months. Operations resulted in a weighted mean (SD) increase in mouth opening of 19.3 (6.3) mm. None of the operations was better than the others for the improvement of mouth opening. We conclude that operations can improve mouth opening in extra-articular trismus, but the evidence is of moderate quality and there is a need for further research.

Single-stage breast reconstruction using Strattice™: A retrospective study.

INTRODUCTION: Strattice™, a porcine acellular dermal matrix, has emerged as a product to augment implant-based breast reconstruction. It aims to resolve problems related to poor tissue coverage of the implant. Presently, evidence justifying the use of Strattice in breast reconstruction is lacking. The objective of this study is to assess the clinical outcomes of a patient cohort that underwent single-stage implant-based breast reconstruction with the additional use of Strattice. METHODS: We conducted a retrospective chart review of patients who underwent single-stage breast reconstruction with the use of Strattice. All cases of breast reconstruction after oncologic or prophylactic mastectomy between 2010 and 2014 in one of eight different centres in the Netherlands were included. Patient demographics, treatment characteristics and clinical outcome data were collected. The outcomes were presented using descriptive statistics, and the associations were evaluated using Fisher's exact test. RESULTS: Eighty-eight patients who underwent either unilateral (60 patients) or bilateral (25 patients) (n = 110 breasts) single-stage breast reconstruction with the use of Strattice were identified. The indication for mastectomy was therapeutic in 69.1% (76) of cases and prophylactic in 30.9% (34) of cases. The reported minor complications included seroma (20.9%), skin necrosis (20.0%), wound dehiscence (11.8%), erythema/inflammation (14.5%) and infection (11.8%). In 22 breasts (22.7%), reoperation was necessary, with explantation of the implant in 11 breasts (11.8%). CONCLUSIONS: In this cohort, the total complication rate was very high (78%). Although most complications were minor, reoperation was performed in 22.7%, with explantation of the implant in 11.8% of breasts. We suggest that patient selection, experience of the surgeon and handling of early complications are factors playing a crucial role in the success of the operation. The use of a Strattice sheet in single-stage implant-based breast reconstruction may be a promising technique, but more evidence from prospective, randomized studies is necessary to justify its use. LEVEL OF EVIDENCE: IV.

Motion coherence detection as a function of luminance level in human central vision.

We studied the changes and invariances of foveal motion detection upon dark adaptation. It is well-documented that dark adaptation affects both spatial and temporal aspects of visual processing. The question we were interested in is how this alters motion coherence detection for moving random texture. To compare motion sensitivity at different adaptation levels, we adjusted the viewing distance for equal detectability of a stationary pattern. At these viewing distances we then measured velocity tuning curves for moving random pixel arrays (RPAs). Mean luminance levels ranged from 50 down to 0.005 cd m-2. Our main conclusion is that foveal velocity tuning is amazingly close to luminance-invariant, down to a level of 0.05 cd m-2. Because different viewing distances, and hence, retinal image sizes were used, we performed two control experiments to assess variations of these two parameters separately. We examined the effects of retinal inhomogeneities using discs of different size and annuli filled with RPAs. Our conclusion is that the central visual field, including the near periphery is still rather homogeneous for motion detection at 0.05 cd m-2, but the fovea becomes unresponsive at the lowest luminance level. Variations in viewing distance had marked effects on velocity tuning, both at the light adapted level and the 0.05 cd m-2 level. The size and type of these changes indicated the effectiveness of distance scaling, and show that deviations from perfect invariance of motion coherence detection were not due to inaccurate distance scaling.

The study population: general characteristics and potential confounding factors.

OBJECTIVE: To test the representativity of the study population and to identify potential selection bias. DESIGN: Non-response analysis and comparison with other representative samples from the Dutch population. Description of physical and clinical biochemical variables as well as health and lifestyle characteristics among low vitamin B6 groups and reference groups. RESULTS AND CONCLUSIONS: The non-response rate for the food frequency questionnaire was 54%; subsequently, non-response for the detail study was 42%. A greater proportion of respondents to the FFQ and of participants in the reference group of the study followed a special dietary regimen or a therapeutic diet or used dietary supplements compared with non-respondents, indicating that we may have selected a somewhat more health conscious reference group. There were no differences in vitamin B6 intake (absolute or per g protein) between participants and the total group of non-respondents for the detail study. Selection of a low B6 group did not result in important bias regarding physical, biochemical or general health and lifestyle characteristics. Exceptions were a difference in the proportion of dieters (younger women) and supplement users (older women) and a difference in creatinine clearance and supplement use between reference and low B6 groups. The differences found, however, were small. Nonetheless, these factors have to be taken into account when analysing and interpreting the results.

Dietary intake among adults with special reference to vitamin B6.

OBJECTIVE: To assess the adequacy of the dietary intake in general, and that of vitamin B6 intake especially. DESIGN AND SUBJECTS: Dietary intake based on 3 d diet-records was assessed among a random sample of the adult Dutch population (the reference group, n = 300) aged 20-79 y, stratified for age and gender and among a group with a low vitamin B6 intake, selected by means of a food frequency questionnaire. RESULTS: Among the reference group, absolute vitamin B6 intake on average amply met the RDA in all age-gender categories, whereas the adequate level of 20 microg vitamin B6 per gram protein, was on average met by men only. The prevalences of a vitamin B6 intake below the minimum requirement (absolute) of 1 mg/d was 1-11% and below the average minimum requirement of 15 microg/g protein was 5-12% for the various age-sex reference groups. Average intake of folate among women of childbearing age did not meet the recommendation of 400 microg/d for those who want to become pregnant. Average intake of iron and iodine was also below recommended levels among women aged 20-49 y. Both absolute vitamin B6 intake and the vitamin B6/protein ratio calculated with the diet records was lower among the low vitamin B6 groups than among the reference groups, indicating that the preselection of groups with low vitamin B6 intakes on the basis of a food frequency questionnaire was successful. Intake of energy and macro- and micronutrients, as well as a nutrient density of the diet were lower among low vitamin B6 groups than among reference groups. CONCLUSIONS: It is concluded that a low vitamin B6 intake is the result of both the quantity (energy) and quality (nutrient density) of the food consumed. The effects of this are not restricted to vitamin B6 and therefore, the low vitamin B6 groups have a combination of relatively low intakes.

Iron intake and iron status among adults in the Netherlands.

OBJECTIVE: To assess the adequacy of iron intake and status, the prevalence of marginal iron status, the physiological and lifestyle factors influencing iron status and the role of dietary factors affecting the bioavailability of iron among Dutch adults. DESIGN: Food consumption was measured with 3 d diet records. Iron status and prevalence of iron deficiency and iron accumulation were evaluated using different criteria. Physical, biochemical and lifestyle characteristics were determined and relationships with iron status were evaluated by bi- and multivariate regression analysis. SUBJECTS: A sample of 444 adults, aged 20-79 y stratified for sex and 10 y age classes, with an overrepresentation of people with a low habitual intake of vitamin B6. RESULTS: Average iron intake was higher than the recommended daily allowance for the Netherlands in all sex-age groups except women aged 20-49, in which group average iron intake was 23% below the recommendation. Early iron deficiency, as reflected in low ferritin levels, was not found among men aged 20-49, but was observed in 5% of women aged 50-79, 11% of men aged 50-79, and 16% of women aged 20-49. Iron deficiency anaemia as reflected in low haemoglobin levels was found in 0-5% of the age-sex groups. Among men and women, 16% and 13% of variance in haemoglobin level, respectively, could be explained by physiological and dietary factors. For ferritin, the proportions were 36% and 34%, respectively. Iron status was correlated negatively with the vegetable fraction of the diet, and positively with factors from the animal fraction (haem iron, animal protein, meat). Further, haemoglobin was positively correlated with body weight among men, and with both age and use of oral contraceptives among women. Both among men and women, blood donorship in the six months prior to the study was negatively associated with serum ferritin levels. CONCLUSIONS: Women aged 20-49 are the adult sex-age group with the greatest risk of developing (an early stage of) iron depletion. The most important dietary factors influencing the iron status are the type of iron (haem/non-haem) and factors affecting the bioavailability of iron.