Is dietary deficiency of calcium a factor in rickets? Use of current evidence for our understanding of the disease in the past

OBJECTIVE

Rickets is considered an indicator of vitamin D deficiency in palaeopathology, but a strand of biomedical thought maintains that dietary calcium deficiency may sometimes play a part in its causation. Our aim is to evaluate the extent to which low calcium intake should be considered as a factor in biocultural interpretations of rickets.

METHODS

We assess published modern epidemiological studies that provide primary data to support claims for a role for dietary calcium deficiency in rickets. We also consider how we might identify, via indicators of calcium intake, populations at risk of calcium deficiency in the past.

RESULTS

Support for dietary calcium deficiency as a cause of rickets is equivocal. Direct measurement of dietary calcium in the past is not possible, but exposure to risk factors for low calcium intake can to some extent be identified.

CONCLUSION

Whilst there is little evidence to alter the view that rickets is essentially an indicator of a population's vitamin D status, occasionally, in very low calcium intake groups, dietary calcium deficiency may play a synergistic role by accentuating the need for vitamin D.

SIGNIFICANCE

The notion that dietary calcium deficiency may be a cause of rickets appears to be gaining currency in bioarchaeological studies. This paper shows that it is unusual for this to be the case, and even then the role of vitamin D remains crucial.

LIMITATIONS

This paper attempts to summarise the current state of biomedical study in an area that is subject to continuing investigation.

The epidemiology of rickets in the 17th-19th centuries: Some contributions from documentary sources and their value to palaeopathologists

This article considers the nature of written sources on the epidemiology of rickets in the post-Mediaeval period, and examines the value of these sources for palaeopathologists. There is a progression from 17th-18th century sources, which generally make ex cathedra, qualitative statements on rickets frequency to, in the 19th century, semi-quantitative geographical surveys of its occurrence, through to reports of percentage prevalence in various groups. Of course, even these latter cannot be directly compared with prevalences calculated from excavated skeletal remains, but there are also considerable difficulties in comparing them with one another, and this effectively precludes synthesis to provide reliable information on geographic and temporal trends at anything more than a very broad-brush level. Their problematic nature mandates a cautious approach when using written sources to shed light on the epidemiology of rickets. For palaeopathologists, a useful way of incorporating these sources into a biocultural approach may be to use them in order to formulate hypotheses that can then be evaluated using skeletal evidence.

Mandibular morphology in two archaeological human skeletal samples from northwest Europe with different masticatory regimes

Mandibular morphology, assessed osteometrically, is studied in two historic human skeletal series (N = 64 individuals) from northwest Europe, one from Zwolle, the Netherlands (19th century CE), the other from Wharram Percy, England (10th-19th century). Both groups show greater dental wear than modern Western populations, but the rate of wear is greater at Wharram Percy than at Zwolle, suggesting a more vigorous masticatory regime. The aim is to evaluate any differences in mandibular morphology between the two groups that might relate to the inferred difference in biomechanical loading upon the chewing apparatus consequent upon the different physical properties of the diets consumed. Results indicate that the mandibles from Zwolle are generally smaller than those from Wharram Percy, especially in the gonial and ramus region and in the height of the post-canine corpus. These differences are consistent with those predicted on biomechanical grounds. That clear differences were observed in two samples whose masticatory regimes were distinct but not very different is an indication of the sensitivity of mandibular morphology to biomechanical input, and supports its value for investigating differences in physical properties of diets in palaeopopulations.

Skeletal manifestations of rickets in infants and young children in a historic population from England

Gross and radiographic changes characteristic of inadequate bone mineralization due to rickets are described in 21 immature skeletons from a 19th century urban population from Birmingham, England. The aims of the study are as follows: to evaluate and if possible augment existing dry-bone criteria for the recognition of rickets in immature skeletal remains; to investigate the value of radiography for the paleopathological diagnosis of rickets; and to compare and contrast the expression of rickets in this group with that previously documented for a rural agrarian population from Wharram Percy, England. Some gross skeletal signs of rickets which were not previously well-documented in paleopathological studies are noted. The worth of radiography for evaluating structural changes to both cortical and trabecular bone in the disease is demonstrated, and features useful for the interpretation of vitamin D deficiency are discussed. The pattern of skeletal elements affected and the severity of changes differs in the Birmingham group from that seen in the comparative rural population. It is emphasized that a variety of factors may influence the expression of rickets in paleopathological material, including rate of skeletal growth, age cohort affected, and intensity of vitamin D deficiency. Nevertheless, careful analysis, not only of the frequency of rickets but also of the degree of severity of lesions and the patterning with respect to skeletal elements affected, may enable more nuanced understanding of the biocultural context of the disease in earlier populations.

Spondylolysis, spondylolisthesis, and lumbo-sacral morphology in a medieval English skeletal population

The prevalence of spondylolysis and spondylolisthesis was studied in an adult skeletal series from a rural English medieval archaeological site. Attempts were made to evaluate the association of three aspects of lumbo-sacral skeletal morphology (pelvic incidence (a measure of the anterior inclination of the sacral table), lumbar transverse process width, and the presence of lumbo-sacral spina bifida occulta) with spondylolysis and spondylolisthesis. Results indicated a high prevalence of spondylolysis compared with a modern reference population, but few cases of spondylolisthesis were identified. Analysis of prevalence with respect to age suggests that in the study population, pars interarticularis defects generally formed late in the growth period or early in adult life. The study group showed a high mean pelvic incidence compared with modern Western Europeans, indicating a more steeply inclined sacral table, which may have elevated the risk of developing pars interarticularis defects. However, no statistically valid association could be demonstrated between the presence/absence of spondylolysis and pelvic incidence in the study material. There was no evidence for a link between lumbar transverse process index or lumbo-sacral spina bifida occulta and spondylolysis/spondylolisthesis. It is concluded that the potential role of lumbo-sacral morphology, as well as of activity regimes, should be considered when interpreting spondylolysis in paleopathological studies. If the frequency of spondylolysis is to some extent an indicator of past activity regimes, it may reflect lifestyle in younger individuals rather than in mature adults. Further work investigating the link between spondylolysis and lumbo-sacral morphological variables in premodern populations would be of value.

Osteoporosis in a population from medieval Norway

Modern populations from Norway and England differ in their experience of osteoporosis, the former showing lower bone mineral density (BMD) and a higher fragility fracture rate. The aim of the present work was to investigate whether this was also the case during the Middle Ages. Age-dependent loss of BMD in the proximal femur was assessed using dual X-ray absorptiometry (DXA) in male and female adult skeletons from a cemetery in the medieval town of Trondheim, Norway. Fracture prevalence was also investigated. Results were compared with those previously reported for a skeletal series from Wharram Percy, a deserted medieval village in England. Results indicate that peak BMD and patterns of age-related loss of BMD in the Norwegian and the English group were similar. Among females, the prevalence of osteoporotic fractures was greater in the Norwegian than in the English population. The BMD results suggest that differences in BMD between English and Norwegians are of recent origin, although given the fairly modest sample sizes, further work is needed to confirm this. Reasons for the greater prevalence of osteoporotic fractures in women in the Norwegian skeletal series are unclear, but the colder climate and greater frequency of hard surfaces may have meant that falls were more frequent, and when they occurred, were more likely to result in fractures than in the rural English group.

Talon cusp in a primary lateral incisor from a medieval child

This paper describes talon cusp in an ancient skeleton and is a rare report of its occurrence in a primary lateral incisor. As well as talon cusp, the affected incisor also shows abnormal widening, probably representing a double tooth. There is also a supernumerary permanent incisor. The report shows that talon cusp existed in British populations more than 600 years before the first written description. A brief review of the literature on the occurrence of talon cusp in the primary dentition is presented.

Measurements of bone mineral density of the radius in a medieval population

The current morbidity in the elderly as a result of osteoporotic fractures has led to interest in the incidence of this condition in past populations. The purpose of this study was to evaluate the technique of scanning of the distal radius with DXA in archaeological bone. The radius is often better preserved in archaeological contexts than bone with higher trabecular content such as the femoral neck or vertebrae. Adult radii (101) from the deserted medieval village site of Wharram Percy were scanned. These skeletal remains represent an homogenous rural population. The scanned individuals were divided into 3 age groups; 18-29, 30-49, and 50+. In both males and females bone loss was statistically significant in the highly trabecular ultra-distal region and the more cortical mid-region after age 50. Only females lost bone in the largely cortical one-third site before age 50. This is in accordance with modern clinical studies in which this loss is attributed to the effects of menopause. In order to assess whether there were differences in bone loss between weight and non-weight-bearing bones, the results were also compared with those from an earlier study of the femoral neck. In both sexes trabecular bone was lost at both anatomical sites after age 50. However, scanning the radius also had the advantage of assessing cortical bone loss. Additionally, despite demonstrable bone loss, there were no Colles or hip fractures in this paleopopulation, suggesting that although an active lifestyle such as that spent in agricultural activity, does not prevent bone loss, it may protect against osteoporotic fracture.

Stable carbon and nitrogen isotope values of bone and teeth reflect weaning age at the Medieval Wharram Percy site, Yorkshire, UK

We report on the measurements of carbon and nitrogen stable isotopes of both bone and teeth from a single site and population (Medieval Wharram Percy), undertaken to explore variations due to weaning in a past population. There have been a number of recent studies of weaning using delta(15)N values of ribs, and we indicate a number of assumptions that must be met before the results of such studies can be correctly interpreted. We found that rib collagen delta(15)N values decrease to adult levels after age 2 years, indicating that weaning occurred at or before this age. Rib collagen delta(13)C values are also more enriched than adult delta(13)C values before age 2 years, and we argue that this is due to the so-called "carnivore" effect in delta(13)C. We measured teeth and rib delta(15)N values from the same individuals and found that for individuals up to age 11 years, tooth dentine delta(15)N is higher than adult rib delta(15)N values, indicating that the dentine was formed during breast-feeding and that there was almost no turnover of dentine since. We observed some decrease in delta(13)C and delta(15)N rib values, compared to adult rib and teeth values, for the few years after weaning that may relate to a theoretically predicted physiological nitrogen imbalance during this period of rapid growth, but this is more likely due to a childhood diet (up to age 9) which was isotopically different from later diet, possibly consisting of a greater proportion of plant foods.

Investigation of the link between visceral surface rib lesions and tuberculosis in a Medieval skeletal series from England using ancient DNA

Seven human skeletons from a large assemblage from a rural English Medieval burial site show lesions, predominantly proliferative in nature, on the visceral surfaces of the ribs. In order to investigate whether these rib lesions were regularly associated with tuberculous infection, these individuals, together with a group of age- and sex-matched control skeletons without bony signs of infection, were subjected to polymerase chain reaction (PCR) assays aimed at detecting traces of DNA from infecting microorganisms of the Mycobacterium tuberculosis complex. The results provided no evidence for any regular association between visceral surface rib lesions and the presence of M. tuberculosis complex DNA in the study group. The significance of these findings for the paleopathological interpretation of visceral surface rib lesions is discussed.

Effects of age and occupation on cortical bone in a group of 18th-19th century British men

The effects of age and occupation on cortical bone in a group of adult males from the 18th-19th century AD skeletal collection from Christ Church Spitalfields, London, were investigated. Cortical bone was monitored using metacarpal radiogrammetry. Individual age at death was known exactly from coffin plates. Occupation for individuals was known from historical sources. Results showed that continued periosteal apposition was evident throughout adult life, but from middle age onwards this was outstripped by about 2:1 by endosteal resorption, so that there was net thinning of cortical bone. The rate of cortical thinning resembled that seen in modern European males. Cross-sectional properties, as measured by second moments of area, bore no relationship to occupation. The results may suggest that, firstly, patterns of loss of cortical bone have remained unchanged in males for at least two centuries in Britain, and secondly, that biomechanical analyses of metacarpal cortical bone may be rather insensitive indicators of intensity of manual activity.

Paleopathological and biomolecular study of tuberculosis in a medieval skeletal collection from England

Nine human skeletons of medieval date from a rural English burial site show signs of skeletal tuberculosis. They were subject to polymerase chain reaction (PCR) assays aimed at detecting traces of DNA from infecting mycobacteria, with the purpose both of confirming the paleopathological diagnosis of tuberculosis and determining in individual cases whether disease was due to M. tuberculosis or M. bovis. In all nine cases, evidence for M. tuberculosis complex DNA was found, and in all instances it appeared that disease was due to M. tuberculosis rather than M. bovis. The significance of the findings for understanding tuberculous infection in rural agrarian communities in medieval England is discussed.

Age-dependent cortical bone loss in women from 18th and early 19th century London

Age-dependent cortical bone loss was investigated in an earlier British population. The study sample comprised female skeletons from the 18th/19th century crypt at Christ Church, Spitalfields, London. Bone loss was monitored using metacarpal radiogrammetry. Age at death was known exactly from coffin plates. Results indicated that peak cortical thickness was less than in modern subjects. Continuing periosteal apposition was evident throughout adulthood, and the rate of increase in metacarpal diameter resembled that in modern subjects. Bone loss from the endosteal surface was evident from the fifth decade onwards, and this outstripped the rate of subperiosteal gain so that there was a net loss of cortical bone with age. Cortical bone loss occurred at a similar rate to that in modern subjects. In contrast to modern populations, there was no evidence that loss of cortical bone was associated with increased propensity to fracture. The present results, together with those previously published for a British medieval skeletal assemblage, suggest that patterns of cortical bone loss in women have remained unchanged over at least the last millennium in Britain. Given the great changes in lifestyle which have occurred during this period, this suggests that lifestyle factors may be rather less important than is sometimes asserted in influencing the severity of osteoporosis, at least as far as loss of cortical bone is concerned.

Alterations in HIV expression in AIDS patients with psoriasis or pruritus treated with phototherapy

BACKGROUND

Ultraviolet light (UVL) upregulates HIV transcription in vitro and in transgenic mice. AIDS-associated psoriasis and pruritus respond to phototherapy.

OBJECTIVE

Our goal was to determine the effect of phototherapy on viral load and immunologic parameters in HIV-positive patients.

METHODS

T cell subsets, p24, plasma cytokines, serum or plasma HIV-RNA, dosage, and antivirals were assessed in HIV-positive patients and negative controls receiving 6 weeks of phototherapy with UVB and in untreated controls.

RESULTS

Phototherapy improved skin conditions without significantly affecting T cell numbers. Plasma p24 increased 2-fold (P = .055) and HIV-RNA levels 4-fold (P = .022) 6 weeks from baseline in patients who entered the trial before March 1995. Later patients who were mostly receiving combination antiviral therapy showed a 4-fold reduction in serum HIV-RNA (P = .012) at 2 weeks. The effect of UVB on viral load at 6 weeks was dependent on the baseline level (P = .006). IL-10 increased and was inversely related to HIV-RNA levels (P = .0267).

CONCLUSION

Phototherapy is associated with HIV load alterations, depending on patients' initial HIV-RNA, antiviral therapy, skin type, and UVL dosage.

The pathogenesis of psoriasis and the mechanism of action of tazarotene

The 3 major features of psoriasis--abnormal differentiation of keratinocytes, hyperproliferation of keratinocytes, and infiltration of inflammatory components into the skin--can be quantified by measuring levels of certain biochemical markers. Psoriasis is associated with upregulation or downregulation of several of these markers. Tazarotene helps to normalize the levels of the markers, thereby bringing about clinical improvement.

Placement of large suprapubic tube using peel-away introducer

We describe a new method for placing a large suprapubic tube and report our experience with 56 patients. This method uses a specially designed fascial dilator and peel-away introducer to place an 18F Foley catheter suprapubically. In our experience the method is simple and effective for the exchange of a small suprapubic tube to an 18F Foley catheter, and for primary placement of a large suprapubic tube. It is easily performed at the bedside or during a minor procedure with the patient under local anesthesia.