Sailors, scurvy and science

Atypical Corneal Ectasia Associated With Vitamin C Deficiency

PURPOSE

To demonstrate a possible correlation between corneal ectasia and vitamin C deficiency.

METHODS

Case series.

RESULTS

This case series covers 3 patients with atypical features of corneal ectasia. All 3 had a peculiar general history and visited our tertiary ophthalmology department complaining about decreased visual acuity. Corneal tomography by Scheimpflug imaging (Pentacam) indicated an irregular astigmatism congruent with a corneal ectasia. A blood test diagnosed vitamin C deficiency.

CONCLUSIONS

To the best of our knowledge, this is the first time a possible correlation between corneal ectasia and vitamin C deficiency is established. Although more research is of course of the essence, it proves useful to determine vitamin C plasma levels in patients presenting with atypical ectasia. To the extent that vitamin C deficiency is indeed diagnosed, it should be substituted orally.

Vitamin C Can Shorten the Length of Stay in the ICU: A Meta-Analysis

A number of controlled trials have previously found that in some contexts, vitamin C can have beneficial effects on blood pressure, infections, bronchoconstriction, atrial fibrillation, and acute kidney injury. However, the practical significance of these effects is not clear. The purpose of this meta-analysis was to evaluate whether vitamin C has an effect on the practical outcomes: length of stay in the intensive care unit (ICU) and duration of mechanical ventilation. We identified 18 relevant controlled trials with a total of 2004 patients, 13 of which investigated patients undergoing elective cardiac surgery. We carried out the meta-analysis using the inverse variance, fixed effect options, using the ratio of means scale. In 12 trials with 1766 patients, vitamin C reduced the length of ICU stay on average by 7.8% (95% CI: 4.2% to 11.2%; p = 0.00003). In six trials, orally administered vitamin C in doses of 1⁻3 g/day (weighted mean 2.0 g/day) reduced the length of ICU stay by 8.6% (p = 0.003). In three trials in which patients needed mechanical ventilation for over 24 hours, vitamin C shortened the duration of mechanical ventilation by 18.2% (95% CI 7.7% to 27%; p = 0.001). Given the insignificant cost of vitamin C, even an 8% reduction in ICU stay is worth exploring. The effects of vitamin C on ICU patients should be investigated in more detail.

Building better drugs: developing and regulating engineered therapeutic proteins

Most native proteins do not make optimal drugs and thus a second- and third-generation of therapeutic proteins, which have been engineered to improve product attributes or to enhance process characteristics, are rapidly becoming the norm. There has been unprecedented progress, during the past decade, in the development of platform technologies that further these ends. Although the advantages of engineered therapeutic proteins are considerable, the alterations can affect the safety and efficacy of the drugs. We discuss both the key technological innovations with respect to engineered therapeutic proteins and advancements in the underlying basic science. The latter would permit the design of science-based criteria for the prediction and assessment of potential risks and the development of appropriate risk management plans. This in turn holds promise for more predictable criteria for the licensure of a class of products that are extremely challenging to develop but represent an increasingly important component of modern medical practice.

Sailors' scurvy before and after James Lind--a reassessment

Scurvy is a thousand-year-old stereotypical disease characterized by apathy, weakness, easy bruising with tiny or large skin hemorrhages, friable bleeding gums, and swollen legs. Untreated patients may die. In the last five centuries sailors and some ships' doctors used oranges and lemons to cure and prevent scurvy, yet university-trained European physicians with no experience of either the disease or its cure by citrus fruits persisted in reviews of the extensive but conflicting literature. In the 20(th) century scurvy was shown to be due to a deficiency of the essential food factor ascorbic acid. This vitamin C was synthesized, and in adequate quantities it completely prevents and completely cures the disease, which is now rare. The protagonist of this medical history was James Lind. His report of a prospective controlled therapeutic trial in 1747 preceded by a half-century the British Navy's prevention and cure of scurvy by citrus fruits. After lime-juice was unwittingly substituted for lemon juice in about 1860, the disease returned, especially among sailors on polar explorations. In recent decades revisionist historians have challenged normative accounts, including that of scurvy, and the historicity of Lind's trial. It is therefore timely to reassess systematically the strengths and weaknesses of the canonical saga.

Causal (mis)understanding and the search for scientific explanations: a case study from the history of medicine

In 1747, James Lind carried out an experiment which proved the usefulness of citrus fruit as a cure for scurvy. Nonetheless, he rejected the earlier hypothesis of Bachstrom that the absence of fresh fruit and vegetables was the only cause of the disease. I explain why it was rational for James Lind not to accept Bachstrom's explanation. I argue that it was the urge for scientific understanding that guided Lind in his rejection and in the development of his alternative theory that humidity was the primary cause of the disease. Central in this process was the search for causal mechanisms which could provide understanding of how the disease developed and which fitted in with the knowledge of the time. Given that the relevant background knowledge and statistical methods were not yet available to Lind, he was right to prefer his own explanation to that of Bachstrom. Although his explanation turned out to be wrong, and Bachstrom's right, from a historical point of view it offered deeper causal understanding of both the development of the disease and the preventive and curative effects of fresh vegetable food. This case study illustrates how the search for causal mechanisms can not only be enlightening, but also very misleading.

Topically applied vitamin C enhances the mRNA level of collagens I and III, their processing enzymes and tissue inhibitor of matrix metalloproteinase 1 in the human dermis

Ascorbic acid (vitamin C) is a cofactor required for the function of several hydroxylases and monooxygenases. It is not synthesized in humans and some other animal species and has to be provided by diet or pharmacologic means. Its absence is responsible for scurvy, a condition related in its initial phases to a defective synthesis of collagen by the reduced function of prolylhydroxylase and production of collagen polypeptides lacking hydroxyproline, therefore, they are unable to assemble into stable triple-helical collagen molecules. In fibroblast cultures, vitamin C also stimulates collagen production by increasing the steady-state level of mRNA of collagen types I and III through enhanced transcription and prolonged half-life of the transcripts. The aim of the experimental work has been to evaluate the effect on dermal cells of a preparation of vitamin C topically applied on one side vs placebo on the other side of the dorsal face of the upper forearm of postmenopausal women. Biopsies were collected on both sides and the level of mRNA measured by non competitive reverse transcription-polymerase chain reaction made quantitative by the simultaneous transcription and amplification of synthetic RNA used as internal standards. The mRNA of collagen type I and type III were increased to a similar extent by vitamin C and that of three post-translational enzymes, the carboxy- and amino-procollagen proteinases and lysyloxidase similarly increased. The mRNA of decorin was also stimulated, but elastin, and fibrillin 1 and 2 were not modified by the vitamin. The expression of matrix metalloproteinases 1, 2, and 9 was not significantly changed, but an increased level of tissue inhibitor of matrix metalloproteinase 1 mRNA was observed without modification of tissue inhibitor of matrix metalloproteinase 2 mRNA. The stimulating activity of topical vitamin C was most conspicuous in the women with the lowest dietary intake of the vitamin and unrelated to the level of actinic damage. The results indicate that the functional activity of the dermal cells is not maximal in postmenopausal women and can be increased.