Osteoporosis, scurvy, and siderosis in Johannesburg bantu

Scurvy: Rare Orthopaedic Complications Associated with Multinutritional Deficiencies

Suboptimal nutrition can lead to deficiencies in micronutrients such as ascorbic acid (vitamin C), which can present with catastrophic neurological sequelae. Deficiencies of vitamin C, vitamin B3 (niacin) and zinc levels contribute to reduced bone density. Vitamin C associated vertebral fractures, although rare in adults, are still treatable if diagnosed early with a thorough clinical and nutritional history, and early supplementation. Radiological clues suggestive of scurvy-induced vertebral fractures can be diagnosed on plain X-ray and MRI spine imaging.

LEARNING POINTS

Although nutritional deficits like scurvy, pellagra and zinc deficiency are rare, early recognition and prompt treatment can prevent critical neurological sequelae.Clinical history including nutritional intake and associated patient symptoms are vital to diagnose scurvy-related vertebral fractures, which are treatable.It is important to note that scurvy can also present in an adult population.

Infectious disease and nutritional deficiencies in early industrialized South Africa

OBJECTIVE

Real industrialization was late to arrive in South Africa and was associated with the development of mining in its northern regions. This paper explores the development and spread of infectious diseases (particularly tuberculosis), against the backdrop of metabolic disease.

MATERIALS

Published data regarding skeletons from various mining sites and historical information are collated, including information from the early accessions into the Raymond A. Dart Collection.

METHODS

While findings from several sites (e.g., Gladstone at Kimberley, Koffiefontein, Witwatersrand Deep Mine and Lancaster Mine) have been described individually, they have not been assessed collectively. This paper provides a broad overview by collating information from these sites, in comparison with a rural, pre-industrialized population.

RESULTS

Malnutrition, including scurvy, was common in most mining groups. Tuberculosis was rare in earlier mining groups, and the first possible skeletal cases only occurred after the establishment of closed housing compounds. From there it spread rapidly across the subcontinent.

CONCLUSIONS

Nutritional insufficiencies / metabolic disease and high death rates, due to trauma and infectious diseases, were common. Tuberculosis in South Africa is closely associated with development of the mining industry.

SIGNIFICANCE

This research highlights the development of tuberculosis in South Africa and its association with the mining industry. The role of migrant labor and the associated housing practices is elucidated.

LIMITATIONS

Sample sizes are limited, but the findings of this study are supported by documentary evidence.

FUTURE RESEARCH

Sample sizes should be increased, and the association between closed compound living and the development of disease further explored.

On a Novel, Simplified Model Framework Describing Ascorbic Acid Concentration Dynamics

Ascorbic acid is an essential aminoacid which interacts in several parts of the human body metabolism. The ascorbic acid concentration is controlled by homeostasis, a biological, autonomous control function in the body. Humans are not able to produce ascorbic acid, and the ascorbic acid concentration is maintained by daily oral digestion. Ascorbic acid is buffered in various tissues, such as the adrenal glands, brain, muscles, and other. Excessive ascorbic acid is extracted from the body through urine and intestines. Measuring ascorbic acid concentration in the body is challenging, and special procedures must be followed when extracting a blood sample and performing a concentration analysis. This paper presents a novel, simplified model framework of the ascorbic acid homeostasis in the human body plasma and tissues, including tissues such as adrenal glands, brain, liver, muscles and bone marrow. These tissues also act as ascorbic acid concentration buffers, in case of low oral supply. The dynamic model framework is based on mass balances of ascorbate acid in various tissues, including tissue buffer terms involving the intestine, kidney, adrenal glands, and other critical and noncritical tissues. The interaction between buffer tissues and fluids is maintained by the body homeostasis using chemical transport protein molecules. Additional usage terms describing energy metabolism, body growth, and immune system response are also included. This dynamic model framework, including the ascorbic acid concentration control system, is simulated with assumed parameters based on available literature. The results indicates that further investigations using experiments, in addition to adaptive model parameter estimation schemes and additional model verification tests are needed in order to identify the various model framework parameters to fit the human body ascorbic acid homeostasis and pharmacokinetics.

Sex-specific patterns in cortical and trabecular bone microstructure in the Kirsten Skeletal Collection, South Africa

OBJECTIVES

The purpose of this study was to provide bone histomorphometric reference data for South Africans of the Western Cape who likely dealt with health issues under the apartheid regime.

METHODS

The 206 adult individuals (_n female = 75, _n male = 131, mean = 47.9 ± 15.8 years) from the Kirsten Skeletal Collection, U. Stellenbosch, lived in the Cape Town metropole from the late 1960s to the mid-1990s. To study age-related changes in cortical and trabecular bone microstructure, photomontages of mid-thoracic rib cross-sections were quantitatively examined. Variables include relative cortical area (Rt.Ct.Ar), osteon population density (OPD), osteon area (On.Ar), bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular spacing (Tb.Sp).

RESULTS

All cortical variables demonstrated significant relationships with age in both sexes, with women showing stronger overall age associations. Peak bone mass was compromised in some men, possibly reflecting poor nutritional quality and/or substance abuse issues throughout adolescence and early adulthood. In women, greater predicted decrements in On.Ar and Rt.Ct.Ar suggest a structural disadvantage with age, consistent with postmenopausal bone loss. Age-related patterns in trabecular bone microarchitecture are variable and difficult to explain. Except for Tb.Th, there are no statistically significant relationships with age in women. Men demonstrate significant negative correlations between BV/TV, Tb.N, and age, and a significant positive correlation between Tb.Sp and age.

CONCLUSIONS

This research highlights sex-specific differences in patterns of age-related bone loss, and provides context for discussion of contemporary South African bone health. While the study sample demonstrates indicators of poor bone quality, osteoporosis research continues to be under-prioritized in South Africa.

Association between serum ferritin and hemoglobin levels and bone health in Korean adolescents: A nationwide population-based study

It is important to identify risk factors for low bone mass at a young age. An influence of iron store on bone health in the general population has been reported but has not been studied in adolescents. This study aimed to investigate the relationship between hemoglobin and serum ferritin levels and bone mineral content (BMC) in South Korean adolescents.This study was based on data collected during the 2009to 2010 Korea National Health and Nutrition Examination Survey. We included 1321 participants aged 10 to 18 years. BMC was measured at the femur and lumbar spine using dual-energy x-ray absorptiometry, and hemoglobin and serum ferritin levels were examined.In boys, hemoglobin and serum ferritin levels were positively associated with BMC of the total femur and lumbar spine after adjusting for confounders, and hemoglobin levels significantly increased as BMC increased at all sites (P for trend = .001 for total femur, .01 for femur neck, and <.001 for lumbar spine). Likewise, serum ferritin levels showed increasing trends according to increasing BMC of the total femur and lumbar spine in boys (P for trend = .04 for total femur; and <.001 for lumbar spine). However, these associations were not observed in girls.This study suggests a positive relationship between serum ferritin and hemoglobin levels and BMC in South Korean adolescent boys.

Osteoporotic Mechanisms

Osteogenic cells are derived from sinusoid vessel walls. When conditions are favourable—a supply of energy, correct concentrations of oxygen and carbon dioxide, the hormone balance on the anabolic and anticatabolic side, the osteogenic factor present—osteogenic precursor cells differentiate to osteoblasts and osteocytes. When the balance is on the catabolic side precursor cells coalesce to form osteoclasts. When catabolic conditions persist osteoclastic activity continues until all the precursor cells are used up.

Phagocytic cells can also enlarge and coalesce to form osteoclasts. Parathyroid hormone is needed for coalescence. The formation of these osteoclasts is stimulated by an increased marrow pressure or exposure of dead bone tissue. Corticosteroids prevent initial enlargement of cells. Excess parathyroid hormone stimulates the production and activity of extra phagocytic osteoclasts.

The hormone balance may approach the catabolic during later stages of pregnancy and after childbirth, after the menopause, during and after the general hormonal decline in old age, when corticosteroids are given for therapeutic purposes, or as a result of the action of contraceptive agents. The effects of stress (caused by the unpleasant emotions, fear, apprehension frustration, jealousy, anxiety, etc, as well as serious illness or trauma) include a rise in blood cortisol levels. A combination of factors may result in corticosteroid levels exceeding the threshold for thrombus formation. This threshold depends on the other chemicals affecting the pituitary-adrenal system that are present. It is abnormally low for contraceptive agents.

These mechanisms of bone formation and removal account for the main types of osteoporosis. A lowered blood flow arises from a decrease or cessation of muscle activity, the effect of catabolic compounds on muscle fibres, or thrombi lodged in vessels supplying muscles and bone. A build-up of pressure stimulates the formation of phagocytic osteoclasts, while until the flow is increased again there is insufficient stimulus for new bone formation.

When catabolic conditions prevail, osteogenic precursor cells coalesce to osteoclasts, and when anticatabolic conditions return, more precursor cells are formed that may proceed to osteoblast and bone formation before the next catabolic episode. With an unfortunate timing of alternations this results in considerable bone loss. In pregnancy the loss is temporary, but after the menopause and in old age there may be a permanent decrease of bone tissue. This type of osteoporosis may also be caused by contraceptive agents. It leads to backache, the increased number of fractured wrists in older women, and intracapsular hip fractures.

Small thrombi cause irreversible osteoporosis. Blood flow through bone is decreased, and vessels in cortical bone blocked. Bone served by these vessels dies, and with prolonged catabolic conditions a considerable amount of dead bone tissue may be present. After phagocytic removal it is not usually replaced. This type of ‘senile’ osteoporosis, which can cause extracapsular hip fractures, is common in old age. It is also the main mechanism of osetoporosis caused by contraceptive agents.

There are racial variations. Negroes are the least susceptible and the Japanese the most susceptible.

In elderly people senile osteoporosis is part of a more generalized condition. The liver and brain are also affected—there are considerable individual variations, but symptoms often include depression and sometimes pyschotic episodes. Like diabetes and thyroid deficiency, an anticatabolic deficiency requires continuous therapy. The anticatabolic agent chosen should be one that reverses corticosteroid effects on bone, liver and brain efficiently, and at the same time has a high Cortisol threshold for thrombus formation.

Serum ferritin levels are positively associated with bone mineral density in elderly Korean men: the 2008-2010 Korea National Health and Nutrition Examination Surveys

A possible negative effect of iron overload on bone metabolism has been suggested by the fact that patients with hemochromatosis, thalassemia, and sickle cell anemia have lower bone mineral density than the general population. However, the influence of iron overload on bone health in the general population is uncertain. The aim of this study was to investigate the relationship between serum ferritin levels and bone mineral density (BMD) in elderly Koreans. A total of 2,943 subjects aged 65 years and over who participated in the 2008-2010 Korea National Health and Nutrition Examination Surveys were included in this study. Age, physical activity, current smoking status, alcohol consumption, education level, household income, and dietary assessment were surveyed by a face-to-face interview. BMD was measured at the lumbar spine and femur by dual-energy X-ray absorptiometry, and other biochemical markers, including serum ferritin, 25-hydroxyvitamin D3, serum alkaline phosphatase, and parathyroid hormone, were assayed. After adjusting for age and body mass index, we found an association between BMD of the total lumbar spine, total femur, and femur neck and levels of alkaline phosphatase, parathyroid hormone, vitamin D3, and daily intake of calcium and protein. Serum ferritin levels were positively associated with BMD of the total lumbar spine, total femur, and femur neck after adjusting for all covariates in men, but not in women. This study suggests a positive association between serum ferritin levels and BMD in elderly South Korean men without hematologic disorders. Further study is warranted to verify the effects of iron on bone metabolism.

Cortical and trabecular bone microarchitecture and turnover in alcohol-induced chronic pancreatitis: a histomorphometric study

Alcohol-induced chronic pancreatitis is associated with bone loss, but bone histomorphometric data describing the mechanism of cortical (Ct) and trabecular (Tb) bone loss are scarce. In this case-control study, we investigated 13 black male patients aged 41.2 +/- 8.9 years with alcohol-induced chronic pancreatitis by routine iliac crest cortical and trabecular histomorphometry and by biochemistry relevant to bone, liver function, and iron overload. Patients showed lower values for Ct thickness (P = 0.018), endocortical (Ec) wall thickness (P = 0.0002), Tb bone volume (0.019), Tb thickness (0.001), Tb wall thickness (P < 0.0001), Ec osteoid thickness (P = 0.001), Ec mineral apposition rate (P = 0.011), and Ec bone formation rate (P = 0.035). Ec eroded surface (P = 0.004) was elevated compared to controls. Tb osteoid thickness (P = 0.14) and Tb mineral apposition rate (P = 0.195) tended to be lower than in controls. Levels of 25-hydroxyvitamin D (P < 0.005), serum magnesium (P = 0.02), and ascorbic acid (P = 0.049) were lower and urine calcium/creatinine ratios higher than in controls. Alkaline phosphatase and gamma-glutamyl transpeptidase (GGT) were negatively correlated but iron markers were positively correlated with bone structural and formation variables. The histomorphometric data were found to be consistent with alcohol bone disease. Osteomalacia was not a feature. Secondary pathogenetic factors were liver disease, hypovitaminosis D and C, diabetes mellitus, and possibly chronic pancreatitis.

Dietary iron overload in the African and hepatocellular carcinoma

Dietary iron overload occurs commonly in parts of sub-Saharan Africa. It results from the consumption of large volumes of traditional beer that is home-brewed in iron pots or drums and consequently has a high iron content. The liver becomes iron overloaded and may develop portal fibrosis or, less often, cirrhosis. A genetic predisposition to the condition has been suggested, but no putative gene has yet been identified. Although originally believed not to cause hepatocellular carcinoma, recent case-control studies have shown African Blacks with dietary iron overload to be at increased risk for the tumour and a causal association has been confirmed in an animal model. The mechanisms of iron-induced malignant transformation are yet to be fully characterised, but the close association between cirrhosis and hepatocellular carcinoma in patients with hereditary haemochromatosis and the lesser association in those with dietary iron overload, suggests that chronic necroinflammatory hepatic disease contributes to the malignant transformation. Increased hepatic iron may, however, also be directly carcinogenic. Probable mechanisms include the generation of reactive oxygen intermediates and the resultant chronic oxidative stress that damages hepatocytes and proteins, causes lipid peroxidation, and induces strand breaks, DNA unwinding, and mutations in tumour-suppressor genes and critical DNA repair genes.

Iron overload in Sub-Saharan Africa: to what extent is it a public health problem?

Excessive deposition of Fe in the organs and tissues of Sub-Saharan Africans was first described in South Africa in 1929. Fe overload, or siderosis, was initially attributed to infections and to metallic poisoning (Cu, Sn, Zn), and then to malnutrition. In 1953 it was hypothesized that it was due primarily to excessive Fe intake derived from foods and drinks prepared in Fe vessels. Recently, in 1992 it was advanced that a gene distinct from any HLA-linked locus may also play a role. As to sequelae, in early research on series of hospital patients, the condition was linked to scurvy, osteoporosis, diabetes, cirrhosis, and latterly, to hepatocellular cancer and tuberculosis. Accordingly, many have concluded that Fe overload is responsible for considerable morbidity and mortality, that adventitious Fe intake should be reduced, and that phlebotomy be recommended for those severely affected. However, there are numerous limitations in the evidence. There are also problems in interpretation, since levels of Fe in the serum are affected additionally by a variety of factors: infection, inflammation, certain cancers and alcohol intake. These considerations complicate attempts to assess to what extent the associations described denote causation, and whether Fe overload has significant ramifications for ill in the general African population. While the adverse sequelae of overload may be less of significance than many believe, the precise pathogenicity of the phenomenon will remain uncertain until further investigations, including prospective studies, are undertaken.

Musculoskeletal manifestations of scurvy

Scurvy occurs in individuals who eat inadequate amounts of fresh fruit or vegetables, often because of dietary imbalances related to advanced age or homelessness. Asthenia, vascular purpura, bleeding, and gum abnormalities are the main symptoms. In 80% of cases, the manifestations of scurvy include musculoskeletal symptoms consisting of arthralgia, myalgia, hemarthrosis, and muscular hematomas. Vitamin C depletion is responsible for structural collagen alterations, defective osteoid matrix formation, and increased bone resorption. Imaging studies may show osteolysis, joint space loss, osteonecrosis, osteopenia, and/or periosteal proliferation. Trabecular and cortical osteoporosis is common. Children experience severe lower limb pain related to subperiosteal bleeding. Laboratory tests show nonspecific abnormalities including anemia and low levels of cholesterol and albumin. The finding of a serum ascorbic acid level lower than 2.5 mg/l confirms the diagnosis. Vitamin C supplementation ensures prompt resolution of the symptoms.

African iron overload

Iron overload is common in rural sub-Saharan African populations that have the custom of drinking a traditional fermented beverage with high iron content. As with both excessive alcohol exposure and HFE hemochromatosis, hepatic portal fibrosis and micronodular cirrhosis are prominent sequelae of African iron overload. Two observations are therefore important in characterizing iron overload in Africa. First, the hepatic iron concentrations associated with African iron overload often far exceed those seen in alcoholic liver disease and histologic changes of alcohol effect are almost always absent. Second, the pattern of iron accumulation in African dietary iron is prominent in both macrophages and hepatic parenchymal cells; this pattern is in contrast to HFE homochromatosis, which is marked by predominantly parenchymal iron-loading. For a long time, it was thought that African iron overload was purely dietary in nature, that increased iron and alcohol in the diet could fully explain markedly elevated tissue iron levels sometimes seen with this condition. Recent studies of pedigrees suggest that, in addition to high dietary iron content, a genetic defect may also be implicated in iron overload in Africans. These studies indicate that the possible defect is different from mutations in the HFE gene frequently found in Caucasians with iron overload, but the putative gene has not been identified. Recent studies also indicate that non-HFE iron overload occurs in African-Americans, but the prevalence and possible genetic basis is yet to be determined.

Effect of transferrin polymorphism on the metabolism of vitamin C in Zimbabwean adults

BACKGROUND

Transferrin is the major iron binding protein in human plasma. In black persons, the transferrin CD phenotype has been associated with alterations in certain markers of iron status.

OBJECTIVE

We studied vitamin C status in a Zimbabwean population according to transferrin phenotype because vitamin C metabolism is influenced by iron-driven oxidative stress.

DESIGN

The study population consisted of 150 black African adults, 90 of whom were at risk of iron overload on the basis of high dietary iron content in the form of traditional beer. Transferrin phenotypes, indirect measures of iron status, and leukocyte ascorbic acid concentrations were determined. The in vitro rate of L-ascorbic acid depletion in sera from different transferrin phenotypes was investigated.

RESULTS

The transferrin phenotype frequencies of transferrin CC and CD were 0.893 and 0.107, respectively. The iron status of transferrin CC and CD subjects was similar. After adjustment for traditional beer consumption, baseline leukocyte vitamin C concentrations were significantly higher in 16 transferrin CD subjects ( +/- SE: 2.10 +/- 0.34 and 2.61 +/- 0.28 fmol/leukocyte in men and women, respectively) than in 134 transferrin CC subjects ( +/- SE: 1.65 +/- 0.11 and 1.99 +/- 0.11 fmol/leukocyte in men and women, respectively; P = 0.024). Oral administration of ascorbic acid (2.0 g every 24 h for 48 h) led to slower rises in leukocyte vitamin C concentrations in subjects with the transferrin CD phenotype than in subjects with the transferrin CC phenotype (P = 0.028). After in vitro supplementation of serum with 570 micromol vitamin C/L, the rate of L-ascorbic acid depletion was significantly lower in subjects of a transferrin CD phenotype than in subjects with the transferrin CC phenotype.

CONCLUSION

Transferrin polymorphism may affect vitamin C status in blacks.

Traditional Beer Consumption and the Iron Status of Spouse Pairs From a Rural Community in Zimbabwe

To examine the relationship between dietary iron exposure through the consumption of traditional beer and the presence of iron overload in black Africans not related by birth, we studied 28 husband and wife pairs from a rural Zimbabwean community. Lifetime traditional beer consumption was estimated by questioning subjects and iron status was assessed by repeated measurements of serum ferritin and transferrin saturation in subjects who were fasting and had received vitamin C supplementation. Each of the 56 study subjects had an estimated lifetime traditional beer consumption <1,000 L. The mean ± standard deviation (SD) concentration of iron in the supernatants of nine samples of traditional beer from the community was 46 ± 10 mg/L. Four of 28 men (14.3%) and no women had the combination of an elevated serum ferritin and a transferrin saturation <70%, suggestive of substantial iron overload. Significant correlations were not found between the iron status of the husbands and their wives or between dietary iron exposure and iron stores. Our findings suggest that dietary iron exposure may not fully explain the development of iron overload in Africans and are consistent with the hypothesis that an iron-loading gene may also be implicated in pathogenesis.

Effect of age and dietary protein level on tissue mineral levels in female rats

Mineral (phosphorus, sulfur, potassium, calcium, magnesium, iron, zinc, copper, and manganese) concentrations were measured in plasma, and several tissues from female Wistar rats (young: 3-wk-old; mature: 6-mo-old) were fed on a dietary regimen designed to study the combined or singular effects of age and dietary protein on mineral status. Three diets, respectively, contained 5, 15, and 20% of bovine milk casein. Nephrocalcinosis chemically diagnosed by increased calcium and phosphorus in kidney was prevented in rats fed a 5% protein diet. Renal calcium and phosphorus were more accumulated in young rats than mature rats. A 5% protein diet decreased hemoglobin and blood iron. The hepatic and splenic iron was increased by a 5% protein diet in mature rats but was not altered in young rats. Mature rats had higher iron in brain, lung, heart, liver, spleen, kidney, muscle, and tibia than young rats. A 5% protein diet decreased zinc in plasma and liver. Zinc in tibia was increased with dietary protein level in young rats but was not changed in mature rats A 5% protein diet decreased copper concentration in plasma of young rats but not in mature rats. Mature rats had higher copper in plasma, blood, brain, lung, heart, liver, spleen, and kidney than young rats. With age, manganese concentration was increased in brain but decreased in lung, heart, liver, kidney, and muscle. These results suggest that the response to dietary protein regarding mineral status varies with age.

Iron accumulation in tissues of magnesium-deficient rats with dietary iron overload

The mineral imbalances in magnesium-deficient rats with dietary iron overload were studied. Forty-four male Wistar rats were divided into six groups and fed six diets, two by three, fully crossed: magnesium adequate or deficient, and iron deficient, adequate, or excess. The concentrations of iron, magnesium, calcium, and phosphorus in tissues of the rats were measured. The results were as follows: (1) The excess iron intake reinforced the iron accumulation in liver and spleen of magnesium deficient rats; (2) The saturation of iron binding capacity was enormously elevated in the magnesium deficient rats fed excess iron; and (3) Dietary iron deprivation diminished the degree of calcium deposition in kidney of magnesium deficient rats. These results suggest that magnesium-deprived rats have abnormal iron metabolism losing homeostatic regulation of plasma iron, and magnesium deficient rats with dietary iron overload may be used as an experimental hemochromatosis model.

Osteoporosis in African hemosiderosis: role of alcohol and iron

This paper aims to examine the relative contributions made by alcohol and iron overload and hypovitaminosis C to the osteoporosis associated with African hemosiderosis. To characterize this bone disorder, we examined double-tetracycline-labeled iliac crest bone biopsies and serum biochemistry in 53 black male drinkers, 38 with (Fe+) and 15 without (Fe-) iron overload, and in controls. We reasoned that abnormalities found in both patient groups were likely to be caused by alcohol abuse and those found only in the Fe+ group to be caused by iron overload and hypovitaminosis C (iron/C-). The patient groups differed only with respect to greater erosion depth (p < 0.05) and abnormal markers of iron overload in the Fe+ group. Ascorbic acid levels were lower in the Fe+ group than in controls (p < 0.001). Bone volume and trabecular thickness were significantly lower in both patient groups compared with controls and therefore likely caused by alcohol. There were no positive correlations between formation and erosion variables in either patient group, which suggests uncoupling of formation from erosion, possibly as a result of alcohol abuse. Prolonged mineralization lag time associated with thin osteoid seams was found in 32% of patients, affecting both groups. This rules out osteomalacia and suggests osteoblast dysfunction, probably caused by alcohol. The number of iron granules in the marrow correlated with erosion depth (r = 0.373, p < 0.01), trabecular number (r = -0.295, p < 0.05), and trabecular separation (r = 0.347, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of iron-deficiency anemia complicated by scurvy and folic acid deficiency

We present a case of a child with iron-deficiency anemia, folic acid deficiency, and scurvy. His anemia proved refractory to treatment with iron until he received both folic acid and vitamin C supplementation. This case illustrates the importance of the evaluation of ascorbic acid and folate status in treating iron-deficiency anemia initially refractory to iron supplementation, because multiple nutrient deficiencies may coexist.

Iron overload in Africa. Interaction between a gene and dietary iron content

BACKGROUND AND METHODS

In contrast to hemochromatosis, which in white populations is inherited through a gene linked to the HLA locus, iron overload in sub-Saharan Africa is believed to result solely from increased dietary iron derived from traditional home-brewed beer. To examine the hypothesis that African iron overload also involves a genetic factor, we used likelihood analysis to test for an interaction between a gene (the hypothesized iron-loading locus) and an environmental factor (increased dietary iron) that determines transferrin saturation and unsaturated iron-binding capacity. We studied 236 members of 36 African families chosen because they contained index subjects with iron overload. Linkage to the HLA region was tested with use of lod scores.

RESULTS

In the index subjects, increased iron was present in both hepatocytes and cells of the mononuclear-phagocyte system. Among family members with increased dietary iron due to the consumption of traditional beer, transferrin saturation in serum was distributed bimodally, with 56 normal values (less than 60 percent saturation) and 44 elevated values; the mean serum ferritin concentration was five times higher in the subjects with elevated transferrin saturation (P less than 0.005). The pedigree analysis provided evidence of both a genetic effect (P less than 0.005) and an effect of increased dietary iron (P less than 0.005) on transferrin saturation and unsaturated iron-binding capacity. In the most likely model, increased dietary iron raised the mean transferrin saturation from 30 to 81 percent and lowered the mean unsaturated iron-binding capacity from 38 to 13 mumol per liter in subjects heterozygous for the iron-loading locus. The hypothesis of tight linkage to HLA was rejected.

CONCLUSIONS

Iron overload in Africa may be caused by an interaction between the amount of dietary iron and a gene distinct from any HLA-linked gene.

Growth plate injury of the long bones in treated beta-thalassemia

In 12 patients affected by thalassemia major who received an intensive transfusion regimen combined with continuous iron chelation therapy (desferrioxamine 50-80 mg/kg daily), radiologic abnormalities of the long bones were observed similar to those observed in rickets and scurvy. These abnormalities were associated with a growth retardation. The pathogenesis of these lesions is uncertain, but probably the toxic effect of desferrioxamine plays an important role in their development. A relative deficiency of vitamins D and/or C cannot be entirely excluded.

Osteoporotic fractures: an unusual presentation of haemochromatosis

The association of haemochromatosis and osteoporosis is well established, but it is unclear whether this is due to iron overload, hypogonadism, liver disease, or diabetes mellitus. We describe a young eugonadal male patient with osteoporotic fractures as a presenting feature of haemochromatosis, suggesting that factors other than hypogonadism contribute to osteoporosis.

The cytological recognition of African siderosis on bone smears

Eight cases of African siderosis primarily recognized on cytological smears are presented and discussed. All the smears were obtained from Jamshidi needle biopsies of vertebral bodies. Six cases showed siderosis only, while a seventh showed two pathological processes on one slide, namely metastatic keratinizing squamous carcinoma and siderosis. The remaining case showed cytological evidence of tuberculosis and siderosis. All cases were histologically confirmed, an additional feature in two cases being osseous tuberculosis which was not evident on the cytological smears. A search of the literature failed to reveal any report on the cytological recognition of this disease, or its association with tuberculosis.

The clinical manifestations of chronic iron overload

Primary or genetic haemochromatosis is an inherited disease characterized by an inappropriate degree of iron absorption with accumulation of excessive amounts of tissue iron. Parenchymal iron accumulation results in the typical clinical features of the disease including hepatic cirrhosis, diabetes, testicular atrophy and skin pigmentation. The disease is inherited in an autosomal recessive manner. The gene for the disease has not been identified but is tightly linked to the A locus of the histocompatibility complex on chromosome 6. The approximate homozygote frequency in Caucasians is 0.3% with an equal sex ratio. Excessive body iron stores have been described in a number of other conditions, particularly alcoholic liver disease. There is increasing evidence that many of these individuals are in fact also suffering from genetic haemochromatosis. Diagnostic tests including serum iron, transferrin saturation, serum ferritin and liver iron concentration make it possible to detect sufferers of the disease. Screening relatives of affected individuals with these tests allows a diagnosis to be made before permanent tissue damage has occurred. Removal of excess iron stores by repeated phlebotomy is the primary treatment. If iron is removed before significant tissue damage has occurred, the complications and natural course of the disease will be prevented provided reaccumulation of iron does not occur. Excessive iron accumulation with resultant organ damage also occurs in anaemias associated with ineffective erythropoiesis and after excessive parenteral iron administration or repeated blood transfusions. Similar clinical features may be seen. Chelation therapy is the mainstay of treatment in these cases where long-term venesection is not possible.

Dietary iron overload persists in rural sub-Saharan Africa

In a survey of 505 rural Zimbabweans, iron overload was found almost exclusively among men who consumed traditional beer brewed in steel drums. Among drinkers aged over 45 years, 23 of 111 men (21%) had high serum ferritin and a transferrin saturation of over 70%, a combination that indicates a risk of liver disease and other pathological effects from excess body iron. Iron overload, which is reported to be decreasing among urban Africans, may remain a public health issue in rural areas where more than 80% of the people of sub-Saharan Africa live.

Iron overload disorders: natural history, pathogenesis, diagnosis, and therapy

Hemochromatosis is a syndrome which, when fully expressed, is manifested by melanoderma , diabetes mellitus, and liver cirrhosis, with iron overload involving parenchymal and reticuloendothelial cells in many organ systems. This clinical presentation may arise as a consequence of either hereditary or acquired abnormalities of iron overload, although the mechanisms are quite different. In hereditary hemochromatosis (also known as primary, or idiopathic, hemochromatosis), increased intestinal iron absorption leads to excessive accumulations of iron, throughout the body, particularly in parenchymal cells. In secondary forms of iron overload including transfusional hemosiderosis, alcoholic cirrhosis, thalassemia, sideroblastic anemia, and porphyria cutanea tarda, iron accumulates in the reticuloendothelial system initially, but with increasing amounts of total body iron, excessive iron deposits eventually accumulate in parenchymal cells throughout the body producing a picture indistinguishable from hereditary hemochromatosis. In this article, the course, prognosis, and therapy of iron overload will be reviewed in detail. Clinical and experimental data concerning the pathogenesis of the different forms of iron overload will be examined critically. In particular, information relating to possible abnormalities of reticuloendothelial function, intestinal mucosal iron transport, and alterations in serum and tissue isoferritin patterns in hereditary hemochromatosis will be analyzed, and possible directions for future research will be suggested. The mode of inheritance and linkage with the major histocompatibility (HLA) complex will be discussed. Theories on the pathogenesis of tissue damage by excess iron will be evaluated. Methods for measuring the extent of iron overload in clinical practice will be described, including measurements of serum iron, serum ferritin, iron absorption, cobalt excretion, desferrioxamine excretion, liver biopsy and tissue iron determinations, and HLA typing. Finally, unresolved problems in the understanding of the disease process, diagnosis, and therapy will be delineated.

Abruptio placentae

Analysis of blood samples from pregnant women has shown that the mean histamine level starts to rise when the plasma ascorbic acid level falls below 1.0 mg/100 ml; it is doubled when the ascorbate level falls to 0.5 mg/100 ml and quadrupled when it falls below 0.2 mg/100 ml. The incidence of abruptio placentae was found to be seven out of 355 (or 2.0%) in women who had plasma ascorbic acid levels above 0.4 mg/100 ml and six out of 31 (19.4%) in women with plasma ascorbate levels below 0.4 mg/100 ml. This difference is highly significant. It is suggested that ascorbic acid deficiency and histamine excess play leading roles in the etiology of abruptio placentae.

The effect of siderosis and ascorbic acid depletion on bone metabolism, with special reference to osteoporosis in the Bantu

1. There is an association between iron overload, ascorbic acid deficiency and osteoporosis in middle-aged South African Bantu males. The iron overload contributes to the ascorbic acid deficiency by accelerating its oxidative catabolism. The object of the present investigation was to explore the possibility that the osteoporosis results from chronic ascorbic acid deficiency.

2. On quantitative microradiography, percentage bone-formation surface was normal but percentage bone-resorption surface was significantly increased in ten osteoporotic subjects compared with seven control subjects.

3. There was a significant inverse correlation between bone mineral density and liver storage iron concentration in thirty-five Bantu subjects. In thirteen individuals aged 39 years or less, liver storage iron concentration was significantly correlated with percentage bone-resorption surface.

4. Guinea-pigs deprived of ascorbic acid for 21 d exhibited both significantly diminished percentage bone-formation surface and increased percentage bone-resorption surface.

5. Guinea-pigs overloaded with iron by injections of iron dextran developed significantly reduced hepatic ascorbic acid concentrations and bone mineral densities; percentage bone-formation surface was significantly diminished and percentage bone-resorption surface significantly increased. Ascorbic acid injection largely prevented the bone changes.

Bone and joint changes in haemochromatosis

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Osteoporosis of lumbar vertebrae and calcification of abdominal aorta in women living in Durban

To try to establish whether mechanical stress and muscular activity in earlier life influence the incidence and severity of spinal osteoporosis in old age lateral x-ray films of the lumbar vertebrae were obtained from three matched groups, each of 100 women 50 to 90 years old. Group A was of rural Bantu accustomed to carrying heavy loads on their heads. Group B was of urban Bantu, mainly in domestic service. Group C was of women of European origin.Severe osteoporosis occurred in three cases from group A, two from group B, and 14 from group C. Lesser degrees of osteoporosis could not be assessed precisely enough for inclusion in these figures. Evenly biconcave vertebral bodies, strongly suggestive of osteomalacia, were seen in 10 from group A, five from group B, and one from group C. In many Bantu subjects the fifth lumbar vertebra appeared flattened though of good radiodensity and with no marked changes in the other vertebrae. Twenty-eight of these were from group A, 16 from group B, and none from group C.About a third of each group showed severe degenerative changes in the spine; another third showed milder changes. More cases of spondylolisthesis occurred in the Bantu groups than in the white group. Severe calcification in the abdominal aorta was noted in 24 women in group C. Mild signs occurred in 35 further women from group C, in six from group B, and in only one from group A.

Effects of iron overload on ascorbic acid metabolism

Studies of the ascorbic acid status in two subjects with idiopathic haemochromatosis and in 12 with transfusional siderosis showed that all had decreased levels of white cell ascorbic acid. The urinary excretion of ascorbic acid was also diminished in those subjects in whom such measurements were made. The administration of ascorbic acid was followed by only a small rise in the urinary ascorbic acid output, while the oxalic acid levels (measured in two subjects) showed a significant rise. These findings resemble those described in siderotic Bantu, and support the thesis that increased iron stores lead to irreversible oxidation of some of the available ascorbic acid.