Consumption of ultra-processed foods and health status: a systematic review and meta-analysis.

Increasing evidence suggests that high consumption of ultra-processed foods (UPF) is associated with an increase in non-communicable diseases, overweight and obesity. The present study systematically reviewed all observational studies that investigated the association between UPF consumption and health status. A comprehensive search of MEDLINE, Embase, Scopus, Web of Science and Google Scholar was conducted, and reference lists of included articles were checked. Only cross-sectional and prospective cohort studies were included. At the end of the selection process, twenty-three studies (ten cross-sectional and thirteen prospective cohort studies) were included in the systematic review. As regards the cross-sectional studies, the highest UPF consumption was associated with a significant increase in the risk of overweight/obesity (+39 %), high waist circumference (+39 %), low HDL-cholesterol levels (+102 %) and the metabolic syndrome (+79 %), while no significant associations with hypertension, hyperglycaemia or hypertriacylglycerolaemia were observed. For prospective cohort studies evaluating a total population of 183 491 participants followed for a period ranging from 3·5 to 19 years, highest UPF consumption was found to be associated with increased risk of all-cause mortality in five studies (risk ratio (RR) 1·25, 95 % CI 1·14, 1·37; P < 0·00001), increased risk of CVD in three studies (RR 1·29, 95 % CI 1·12, 1·48; P = 0·0003), cerebrovascular disease in two studies (RR 1·34, 95 % CI 1·07, 1·68; P = 0·01) and depression in two studies (RR 1·20, 95 % CI 1·03, 1·40; P = 0·02). In conclusion, increased UPF consumption was associated, although in a limited number of studies, with a worse cardiometabolic risk profile and a higher risk of CVD, cerebrovascular disease, depression and all-cause mortality.

Lifestyle and biological factors influence the relationship between mental health and low-grade inflammation.

Mental health modulates the risk of common chronic conditions. Although inflammation is thought to partly explain this link, its relation with mental health is still unclear and largely unexplored. We investigated three scales assessing psychological resilience (CD-RISC), depression symptoms (PHQ9-6) and mental wellbeing (SF36-MCS) in an Italian adult population cohort (Nmax = 16,952). This showed a slightly higher frequency of men, more educated and younger participants, compared to samples with incomplete questionnaires. We performed stepwise generalized linear models to test the association between each scale and INFLA-score, a composite blood-based inflammation index. At each step, a class of potential mediators was included in the model, namely health conditions, lifestyle factors, or both (full model). Full model analysis was also conducted on single blood markers involved in the inflammatory process. In the baseline model, we observed significant associations of PHQ9-6 (standardized ß(SE) = 0.024(0.009), p = 8.9 × 10-3) and SF36-MCS (ß(SE) = -0.021(0.008), p = 7 × 10-3) with INFLA-score. These associations survived adjustment for health conditions but not for lifestyle factors, which explained 81% and 17% of the association with PHQ9-6 and SF36-MCS. Significant associations (p < 4.2 × 10-3) after mediator adjustment were observed for single low-grade inflammation markers, including platelet distribution width (with PHQ9-6 and CD-RISC), granulocyte- and neutrophil-to-lymphocyte ratios, monocyte and lymphocyte fractions (with SF36-MCS). After imputation of missing data, we observed substantially consistent associations. These findings suggest that the relationship between mental health and low-grade inflammation is largely influenced by lifestyle. However, the associations with specific biomarkers related to inflammation are partly independent and might be explained by biological factors.

[Chondrosarcoma of the hand arising from multiple enchondromas: a case report]. / Chondrosarkom an der Hand bei multiplen Enchondromen: ein Fallbericht.

Malignancy occurs more often in multiple enchondromas than in solitary enchondromas. In the hands the rate is about 14%. We amputated the third ray of the hand in a young man with recurrence of an enchondroma. The histology showed a low grade chondrosarcoma. The patient had no tumour recurrence or metastasis in the following 5 years. We describe the evaluation as well as the treatment and outline the literature.

Impact of combined healthy lifestyle factors on survival in an adult general population and in high-risk groups: prospective results from the Moli-sani Study.

BACKGROUND: There is poor knowledge on the association between combined lifestyles with mortality risk among individuals at high risk, and little is known on the biological mechanisms that could be on the pathway. METHODS: Longitudinal analysis on 22 839 individuals from the Moli-sani Study (Italy, 2005-2010). Among them, we identified 5200 elderly individuals (≥65 year), 2127 subjects with diabetes and 1180 with cardiovascular disease (CVD) at baseline. A healthy lifestyle score (HLS) was calculated, allocating 1 point for each of the following: abstention from smoking; adherence to Mediterranean diet; physical activity; absence of abdominal obesity. Hazard ratios (HR) with 95% confidence intervals (95%CI) were calculated by multivariable Cox regression and competing risk models. RESULTS: During 8.2 years of follow-up, 1237 deaths occurred. In the general population, adherence to all four healthy lifestyles, compared with none or 1, was associated with lower risk of all-cause (HR = 0.53; 95%CI:0.39-0.72), CVD (HR = 0.54; 0.32-0.91), cancer (HR = 0.62; 0.39-1.00) and mortality from other causes (HR = 0.39; 0.19-0.81). A 1-point increase in HLS was associated with 20%, 22% and 24% lower risk of total mortality among the elderly, in subjects with diabetes or CVD, respectively. Traditional (e.g. blood lipids), inflammatory (e.g. C-reactive protein) and novel biomarkers (e.g. markers of cardiac damage) accounted for up to 24% of the association of HLS with all-cause mortality risk in the general population. CONCLUSIONS: The impact of combined four healthy lifestyles on survival was considerable, both in the general population and among high-risk subgroups. Inflammatory and novel biomarkers of CVD risk explained a substantial proportion of this association.

Consumption of whole grain food and its determinants in a general Italian population: Results from the INHES study.

BACKGROUND AND AIMS: Whole grain (WG) food consumption is associated with lower risk of cardiovascular disease, cancer and neurological diseases. The aim of this study was to assess the consumption of WG food and its major demographic, socioeconomic, psychosocial and behavioral determinants in a general Italian population. METHODS AND RESULTS: Data were from the Italian Nutrition & Health Survey (INHES), a telephone-based survey established in 2010-2013 including 9422 participants aged ≥5 years from all over Italy. WG food intake was assessed by the European Food Propensity Questionnaire and included bread, pasta, breakfast cereals, biscuits and WG soups. WG consumption was categorized as none, occasional (<1 time/week) and regular (≥1 time/week). Overall, 26.9% of the sample reported a regular consumption of WG food (27.2% of adults aged 20-97 y, and 21.9% of children/adolescents aged 5-19 y). In both age-groups, the major food source contributing to total WG intake was WG bread followed by WG pasta. Among adults, greater consumption of WG was associated with healthier lifestyle (e.g. sport activity), and higher educational level. Eating meals outside of the house in adults, and spending >2 h/day watching TV in children/adolescents were inversely associated with WG intake. CONCLUSIONS: The percentage of WG consumers in Italy in 2010-2013 appears to be quite low and still below that recorded in other countries of Europe where consumption is frequently over 50 percent. WG consumption is likely to be influenced by socioeconomic status and is associated with a number of psychosocial factors, meal patterns and eating-related behaviors.

Learning by counting blood platelets in population studies: survey and perspective a long way after Bizzozero.

Platelet count represents a useful tool in clinical practice to discriminate individuals at higher risk of bleeding. Less obvious is the role of platelet count variability within the normal range of distribution in shaping the individual's disease risk profile. Epidemiological studies have shown that platelet count in the adult general population is associated with a number of health outcomes related to hemostasis and thrombosis. However, recent studies are suggesting a possible role of this platelet index also as an independent risk factor. In this review of adult population studies, we will first focus on known genetic and non-genetic determinants of platelet number variability. Next, we will evaluate platelet count as a marker and/or a predictor of disease risk and its interaction with other risk factors. We will then discuss the role of platelet count variability within the normal distribution range as a contribution to disease and mortality risk. The possibility of considering platelet count as a simple, inexpensive indicator of increased risk of disease and death in general populations could open new opportunities to investigate novel platelet pathophysiological roles as well as therapeutic opportunities. Future studies should also consider platelet count, not only platelet function, as a modulator of disease and mortality risk.

Diet and primary prevention of stroke: Systematic review and dietary recommendations by the ad hoc Working Group of the Italian Society of Human Nutrition.

BACKGROUND AND AIMS: To systematically review the latest evidence on established and emerging nutrition-related risk factors for incidence of and mortality from total, ischemic and haemorrhagic strokes. The present review was conducted in the framework of the work carried out through 2015 and 2016 for the preparation of the Italian Guidelines for the Prevention and Treatment of Stroke, 8th Edition, by ISO-SPREAD (Italian Stroke Organization and the Stroke Prevention and Educational Awareness Diffusion). METHODS AND RESULTS: Systematic review of articles focused on primary prevention of stroke published between January 2013 to May 2016 through an extensive search of the literature using MEDLINE/PUBMED, EMBASE and the Cochrane Library. Articles were ranked according to the SIGN methodology while the GRADE system was used to establish the strength of recommendations. As a result of our literature search, we examined 87 meta-analyses overall (mainly of prospective studies), a few isolated more recent prospective studies not included in the meta-analyses, and a smaller number of available randomized controlled trials and case-control studies. Based on the analysis of the above articles, 36 Syntheses of the available evidence and 36 Recommendations were eventually prepared. The present document was developed by organizing the available evidence into three individual areas (nutrients, food groups and dietary patterns) to provide a systematic and user-friendly overview of the available evidence on the relationship between nutrition and primary prevention of stroke. Yet analysis of foods and food patterns allowed translating the information about nutrients in a tool more amenable to use in daily life also in the light of the argument that people eat foods rather than nutrients. CONCLUSIONS: The present literature review and dietary recommendations provide healthcare professionals and all interested readers with a useful overview for the reduction of the risk of total, ischemic and haemorrhagic stroke through dietary modifications.

Serum vitamin D deficiency and risk of hospitalization for heart failure: Prospective results from the Moli-sani study.

BACKGROUND AND AIMS: Evidence indicates that Vitamin D deficiency may be associated with increased risk of cardiovascular disease, although findings on risk of heart failure (HF) are controversial. We investigated the relationship between serum Vitamin D and the incidence of hospitalization for HF in a large prospective cohort of Italian adults. METHODS AND RESULTS: 19,092 (49% men, age range 35-99 years) HF-free individuals from the Moli-sani study, with complete data on serum Vitamin D (25-hydroxyvitamin) levels and incident hospitalized HF, were analysed. The cohort was followed up for a median of 6.2 years. Baseline serum Vitamin D levels were categorized in deficient (<10 ng/mL), insufficient (10-29 ng/mL), and normal (≥30 ng/mL) Incident cases of hospitalization for HF were identified by linkage with the regional hospital discharge registry. Hazard ratios (HRs) were calculated using Cox-proportional hazard models. The prevalence of normal, insufficient or deficient levels of Vitamin D was 12.2%, 79.6% and 8.2%, respectively. During follow-up, 562 admissions to hospital for HF were identified. The incidence of HF was 1.6%, 2.9% and 5.3%, respectively in subjects with normal, insufficient and deficient levels of Vitamin D. After multivariable analysis, individuals with deficiency of Vitamin D had a higher risk of hospitalization for HF (HR: 1.61, 95%CI: 1.06-2.43) than those with normal levels. Further adjustment for subclinical inflammation did not substantially change the association between Vitamin D deficiency and HF. CONCLUSION: Deficiency of Vitamin D was associated, independently of known HF risk factors, with an increased risk of hospitalization for HF in an Italian adult population.

Mediterranean-type diet is associated with higher psychological resilience in a general adult population: findings from the Moli-sani study.

BACKGROUND/OBJECTIVE: Psychological resilience is a measure of stress coping ability and has been associated with favourable health outcomes. While evidence on the relationship of dietary habits with a number of psychosocial conditions is available, there is lack of studies on their association with psychological resilience in a general adult population. SUBJECTS/METHODS: Cross-sectional analysis on 10 812 subjects recruited within the cohort of the Moli-sani study (2005-2010). Psychological resilience was measured by the 25-item Connor-Davidson Psychological Resilience Scale. Food intake was recorded by the EPIC food frequency questionnaire and adherence to Mediterranean diet was appraised by both a Greek Mediterranean diet score and an Italian Mediterranean Index. Empirically derived dietary patterns were obtained by principal factor analysis. Multivariable linear regression analysis (95%CI) was used to test the association between dietary scores and psychological resilience. RESULTS: Higher adherence to Mediterranean-type diets or consumption of a vegetable-based dietary pattern (obtained from principal factor analysis) were positively associated with psychological resilience (ß=0.43; 95%CI: 0.19-0.66, ß=0.92; 0.69-1.16, and ß=1.18; 0.93-1.44, for Greek Mediterranean diet score, Italian Mediterranean Index and the 'Olive oil and vegetables pattern', respectively). Dietary polyphenol or antioxidant intakes and greater variety in fruit and vegetable consumption were also positively associated with psychological resilience, while the associations with Western-like diets were weak. CONCLUSIONS: In conclusion, Mediterranean diet, vegetable-based dietary patterns and better diet quality were all positively associated with higher psychological resilience, whereas Western-type diets were not.

Fish intake is associated with lower cardiovascular risk in a Mediterranean population: Prospective results from the Moli-sani study.

BACKGROUND AND AIMS: Fish consumption reportedly reduces the risk of heart disease, but the evidence of cardiovascular advantages associated with fish intake within Mediterranean cohorts is limited. The aim of this study was to test the association between fish intake and risk of composite coronary heart disease (CHD) and stroke in a large population-based cohort adhering to Mediterranean Diet. METHODS AND RESULTS: Prospective analysis on 20,969 subjects free from cardiovascular disease at baseline, enrolled in the Moli-sani study (2005-2010). Food intake was recorded by the Italian version of the EPIC food frequency questionnaire. Hazard ratios were calculated by using multivariable Cox-proportional hazard models. During a median follow-up of 4.3 years, a total of 352 events occurred (n of CHD = 287 and n of stroke = 66). After adjustment for a large panel of covariates, fish intake ≥4 times per week was associated with 40% reduced risk of composite CHD and stroke (HR = 0.60; 95%CI 0.40-0.90), and with 40% lower risk of CHD (HR = 0.60; 95%CI 0.38-0.94) as compared with subjects in the lowest category of intake (<2 times/week). A similar trend of protection was found for stroke risk although results were not significant (HR = 0.62; 95%CI 0.26-1.51). When fish types were considered, protection against the composite outcome and CHD was confined to fatty fish intake. CONCLUSIONS: Fish intake was associated with reduced risk of composite fatal and non-fatal CHD and stroke in a general Mediterranean population. The favourable association was likely to be driven by fatty fish.

Food group consumption in an Italian population using the updated food classification system FoodEx2: Results from the Italian Nutrition & HEalth Survey (INHES) study.

BACKGROUND AND AIM: Dietary habits evolve over time, being influenced by many factors and complex interactions. This work aimed at evaluating the updated information on food group consumption in Italy. METHODS AND RESULTS: A total of 8944 (4768 women and 4176 men) participants aged >18 years from all over Italy recruited in 2010-13 (Italian Nutrition & HEalth Survey, INHES) was analyzed. The recruitment was performed using computer-assisted-telephone-interviewing and one-day 24-h dietary recall retrieved from all participants. The updated, second version, of FoodEx2 food classification system was applied to extract data on food group consumption. The participation rate was 53%; 6.2% of the participants declared to follow a special diet, the most prevalent being hypo-caloric diets (55.7% of special diets). Men compared to women presented significantly higher intakes of "grains and grain-based products", "meat and meat products", "animal and vegetable fats and oils and primary derivatives" and "alcoholic beverages" (P for all<0.001); moreover, men had lower intakes of "milk and dairy products", "water and water-based beverages" and "products for non-standard diets, food imitates and food supplements" (P for all<0.001). Differences in food group intake among age groups, geographical regions and educational level groups were also identified (P for all<0.05). CONCLUSIONS: Data on the consumption of more than 70 food groups and sub-groups were illustrated in different strata. The present analysis could be considered as an updated source of information for future nutrition research in Italy and in the EU.

Challenges to the Mediterranean diet at a time of economic crisis.

AIMS: The traditional Mediterranean diet (MD) is reportedly associated with lower risk of major chronic diseases and long considered to contribute to the reduced rates of cardiovascular and cerebrovascular events and to the highest life expectancy in adults who lived near the Mediterranean Sea. But despite its widely documented health benefits, adherence to this dietary pattern has been rapidly declining over the last decades due to a clear socioeconomic influence. The present review provides an overview of the evidence on the current major determinants of adherence to the Mediterranean diet, with a particular emphasis on Mediterranean Countries at a time of economic crisis; second it explores emerging socioeconomic inequalities in other domains of healthy dietary behaviours such as dietary variety, access to organic foods and food purchasing behaviour. DATA SYNTHESIS: According to ecological evidence, the Mediterranean Countries that used to have the highest adherence to the Mediterranean pattern in the Sixties, more recently experienced the greatest decrease, while Countries in Northern Europe and some other Countries around the world are currently embracing a Mediterranean-like dietary pattern. A potential cause of this downward trend could be the increasing prices of some food items of the Mediterranean diet pyramid. Recent evidence has shown a possible involvement of the economic crisis, material resources becoming strong determinants of the adherence to the MD just after the recession started in 2007-2008. Beyond intake, the MD also encourages increasing dietary diversity, while international dietary recommendations suggest replacing regular foods with healthier ones. CONCLUSIONS: Socioeconomic factors appear to be major determinants of the adherence to MD and disparities also hold for other indices of diet quality closely related to this dietary pattern.

Association of pasta consumption with body mass index and waist-to-hip ratio: results from Moli-sani and INHES studies.

BACKGROUND/OBJECTIVES: Pasta as a traditional component of Mediterranean diet (MeD) in Italy has not been studied in detail in the management of body weight. This study aimed at evaluating the association of pasta intake with body mass index (BMI) and waist-to-hip ratio, in two large epidemiological datasets. SUBJECTS/METHODS: A total of 14 402 participants aged ⩾35 years randomly recruited from the general population of the Molise region (Moli-sani cohort) and 8964 participants aged >18 years from all over Italy (Italian Nutrition & HEalth Survey, INHES) were separately analyzed. The European Prospective Investigation into Cancer and Nutrition (EPIC)-food frequency questionnaire and one 24-h dietary recall were used for dietary assessment. Weight, height, waist and hip circumference were measured in Moli-sani or self-reported in INHES. Residuals methodology corrected for either total energy intake or body weight was used for the analysis of pasta intake. RESULTS: Higher pasta intake was associated with better adhesion to MeD in both genders (P for both<0.001). In the Moli-sani study, after multivariable analysis, pasta-energy residuals were negatively associated with BMI in women but not in men (ß-coef=-0.007, P=0.003 for women and ß-coef=-0.001, P=0.58 for men). When pasta intake-body weight residuals were used, pasta intake was significantly and negatively associated with BMI in crude and multi-adjusted models (including adhesion to MeD) in both genders and Moli-sani and INHES studies (for all ß-coef<0, P<0.05). In the Moli-sani study, pasta-body weight residuals were significantly and negatively associated with waist and hip circumference and waist-to-hip ratio (for all ß-coef<0, P<0.05). CONCLUSIONS: As a traditional component of MeD, pasta consumption was negatively associated with BMI, waist circumference and waist-to-hip ratio and with a lower prevalence of overweight and obesity.

Flavonoid and lignan intake in a Mediterranean population: proposal for a holistic approach in polyphenol dietary analysis, the Moli-sani Study.

BACKGROUND/OBJECTIVES: The objective of this study is to extract and assess data on the dietary intake of flavonoids and lignans in a healthy free-living Mediterranean population, using newly updated harmonized European Union food composition data. This work also aimed at analyzing in a holistic way the total content of the diet in major classes of polyphenols. SUBJECTS/METHODS: Six thousand nine hundred and eighty-one men and 7048 women (aged ⩾ 35 years) of the Moli-sani cohort, randomly recruited from the general population, were analyzed. The European Prospective Investigation into Cancer (EPIC) and Nutrition-Food Frequency Questionnaire was used for dietary assessment. The polyphenol content of each food group was evaluated using Eurofir BioActive Substances in Food Information System and the United States Department of Agriculture food composition tables (FCTs), when data were missing. Flavonol, flavone, flavanone, flavanol, anthocyanin, isoflavone and lignan intakes were calculated and polyphenol antioxidant content (PAC) score (-28, 28) constructed, to assess the total content of the diet in these nutrients. RESULTS: Seasonal and citrus fruits, leafy, grain, pod and root vegetables, and onions and garlic accounted for different proportions (11-70%) of the total intake of different polyphenols. Within the Moli-sani population, men or older, or no/former smokers, or physically active or obese/overweight individuals presented higher consumption of flavonoids, lignans and PAC score (P for all <0.01). Multiple regression analysis showed that PAC score and its seven components were positively associated with Mediterranean diet (MeD) adherence in both genders (ß-coefficient >0, P<0.001). In addition, 1 unit increase in PAC score was associated with 7.1-7.8% increase in the likelihood of high MeD adherence (P<0.001). CONCLUSIONS: The intake of flavonoids and lignans in an European Union population was calculated using harmonized European Union FCT data. In addition, a holistic approach in dietary analysis of polyphenol intake was proposed.

Decline of the Mediterranean diet at a time of economic crisis. Results from the Moli-sani study.

BACKGROUND AND AIMS: Adherence to Mediterranean diet (MD) is reportedly declining in the last decades. We aimed to investigate the adherence to MD over the period 2005-2010 and exploring the possible role of the global economic crisis in accounting for the changing in the dietary habits in Italy. METHODS AND RESULTS: Cross-sectional analysis in a population-based cohort study which randomly recruited 21,001 southern Italian citizens enrolled within the Moli-sani study. Food intake was determined by the Italian EPIC food frequency questionnaire. Adherence to MD was appraised by the Italian Mediterranean Index (IMI). A wealth score was derived to evaluate the economic position and used together with other socioeconomic indicators. Highest prevalence of adherence to MD was observed during the years 2005-2006 (31.3%) while the prevalence dramatically fell down in the years 2007-2010 (18.3%; P<0.0001). The decrease was stronger in the elderly, less affluent groups, and among those living in urban areas. Accordingly, we observed that in 2007-2010 socioeconomic indicators were strongly associated with higher adherence to MD, whereas no association was detected in the years before the economic crisis began; both wealth score and education were major determinants of high adherence to MD with 31% (95%CI: 18-46%) higher adherence to this pattern within the wealthier group compared to the less affluent category. CONCLUSION: Adherence to MD has considerably decreased over the last few years. In 2007-2010 socioeconomic indicators have become major determinants of adherence to MD, a fact likely linked to the economic downturn.

[Factitious disorder and self-mutilation in hand and plastic surgery]. / Artifizielle Störungen und selbstverletzendes Verhalten in der Hand- und Plastischen Chirurgie.

Self-mutilation in the context of factitious disorder can lead to prolonged and complicated treatment in every medical field. Because of a prevalence of 1-5% in hospitalised patients, it is important to be aware of this disorder to protect patients from self- and foreign-induced harm. Often the patient history gives important hints. The different manifestations of this disorder, the specific doctor-patient relationship, several techniques of confrontation and current treatment are presented. Clinical cases from the fields of hand and plastic surgery are presented.

[Intramedullary Kirschner wire osteosynthesis in treatment of distal metacarpal fractures]. / Die intramedulläre Kirschner-Drahtosteosynthese zur Behandlung distaler Metakarpalfrakturen.

The intramedullary Kirschner wire fixation of distal metacarpal fractures reported by Foucher et al. combines the known advantages of intramedullary implants with a reduction of iatrogenic soft tissue trauma. We applied this minimal invasive internal fixation technique in 38 patients with fractures dislocated by more than 20 degrees and/or with rotatory deformity. After opening the intramedullary cavity from the base of the respective metacarpal bone and after fracture reduction, two pre-bent Kirschner wires were intramedullary inserted in an orthograde fashion. The pre-bent distal end of the wire in the form of a hockey club allows an additional closed reduction of the displaced distal fracture fragment. Intraoperative complications did not occur. A fixation in a plaster splint followed for one week only. The elastic fixation of the wires working as springs is stable enough to allow physiotherapeutic exercises. After the third postoperative week, the intensity of physical exercise was increased. 36 of the 38 patients were followed. With one exception, all fractures were healed in a proper position. The wires were removed under local anaesthesia on an outpatient basis after six to eight weeks and full mobility of the fingers was achieved in 34 patients at that time. Complications included one redislocation and one distal wire perforation.

High and low oxygen affinity conformations of T state hemoglobin.

To understand the interplay between tertiary and quaternary transitions associated with hemoglobin function and regulation, oxygen binding curves were obtained for hemoglobin A fixed in the T quaternary state by encapsulation in wet porous silica gels. At pH 7.0 and 15 degrees C, the oxygen pressure at half saturation (p50) was measured to be 12.4 +/- 0.2 and 139 +/- 4 torr for hemoglobin gels prepared in the absence and presence of the strong allosteric effectors inositol hexaphosphate and bezafibrate, respectively. Both values are in excellent agreement with those found for the binding of the first oxygen to hemoglobin in solution under similar experimental conditions. The corresponding Hill coefficients of hemoglobin gels were 0.94 +/- 0.02 and 0.93 +/- 0.03, indicating, in the frame of the Monod, Wyman, and Changeux model, that high and low oxygen-affinity tertiary T-state conformations have been isolated in a pure form. The values, slightly lower than unity, reflect the different oxygen affinity of alpha- and beta-hemes. Significantly, hemoglobin encapsulated in the presence of the weak effector phosphate led to gels that show intermediate oxygen affinity and Hill coefficients of 0.7 to 0.8. The heterogeneous oxygen binding results from the presence of a mixture of the high and low oxygen-affinity T states. The Bohr effect was measured for hemoglobin gels containing the pure conformations and found to be more pronounced for the high-affinity T state and almost absent for the low-affinity T state. These findings indicate that the functional properties of the T quaternary state result from the contribution of two distinct, interconverting conformations, characterized by a 10-fold difference in oxygen affinity and a different extent of tertiary Bohr effect. The very small degree of T-state cooperativity observed in solution and in the crystalline state might arise from a ligand-induced perturbation of the distribution between the high- and low-affinity T-state conformations.