Portable light transmission measuring system for preserved corneas

Abstract Background The authors have developed a small portable device for the objective measurement of the transparency of corneas stored in preservative medium, for use by eye banks in evaluation prior to transplantation. Methods The optical system consists of a white light, lenses, and pinholes that collimate the white light beams and illuminate the cornea in its preservative medium, and an optical filter (400–700 nm) that selects the range of the wavelength of interest. A sensor detects the light that passes through the cornea, and the average corneal transparency is displayed. In order to obtain only the tissue transparency, an electronic circuit was built to detect a baseline input of the preservative medium prior to the measurement of corneal transparency. The operation of the system involves three steps: adjusting the "0 %" transmittance of the instrument, determining the "100 %" transmittance of the system, and finally measuring the transparency of the preserved cornea inside the storage medium. Results Fifty selected corneas were evaluated. Each cornea was submitted to three evaluation methods: subjective classification of transparency through a slit lamp, quantification of the transmittance of light using a corneal spectrophotometer previously developed, and measurement of transparency with the portable device. Conclusion By comparing the three methods and using the expertise of eye bank trained personnel, a table for quantifying corneal transparency with the new device has been developed. The correlation factor between the corneal spectrophotometer and the new device is 0,99813, leading to a system that is able to standardize transparency measurements of preserved corneas, which is currently done subjectively.

Innovative treatments for shelf-life extension of whole and fresh-cut fruit

Maintaining the postharvest quality of whole and fresh-cut fruit during storage and distribution is the major challenge facing fruit industry. For this purpose, industry adopt a wide range of technologies to enable extended shelf-life. Many factors can lead to loss of quality in fresh product, hence the common description of these products as ‘perishable’. As a consequence normal factors such as transpiration and respiration lead ultimately to water loss and senescence of the product. Fruits and vegetables are living commodities and their rate of respiration is of key importance to maintenance of quality. It has been commonly observed that the greater the respiration rate of a product, the shorter the shelf-life. The principal problem for fresh-cut fruit industries is the relative shorter shelf-life of minimally processed fruit (MPF) compared to intact product. This fact is strictly connected with the higher ethylene production of fruit tissue stimulated during fresh-cut processing (peeling, cutting, dipping). 1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene action and several researches have shown its effectiveness on the inhibition of ripening and senescence incidence for intact fruit and consequently on their shelf-life extension. More recently 1-MCP treatment has been tested also for shelf-life extension of MPF but discordant results have been obtained. Considering that in some countries 1-MCP is already a commercial product registered for the use on a number of horticultural products, the main aim of this actual study was to enhance our understanding on the effects of 1-MCP treatment on the quality maintenance of whole and fresh-cut climacteric and non-climacteric fruit (apple, kiwifruit and pineapple). Concerning the effects of 1-MCP on whole fruit, was investigated the effects of a semi-commercial postharvest treatment with 1-MCP on the quality of Pink Lady apples as functions of fruit ripening stage, 1-MCP dose, storage time and also in combination with controlled atmospheres storage in order to better understand what is the relationship among these parameters and if is possible to maximize the 1-MCP treatment to meet the market/consumer needs and then in order to put in the market excellent fruit. To achieve this purpose an incomplete three-level three-factor design was adopted. During the storage were monitored several quality parameters: firmness, ripening index, ethylene and carbon dioxide production and were also performed a sensory evaluations after 6 month of storage. In this study the higher retention of firmness (at the end of storage) was achieved by applying the greatest 1-MCP concentration to fruits with the lowest maturity stage. This finding means that in these semi-commercial conditions we may considerate completely blocked the fruit softening. 1-MCP was able to delay also the ethylene and CO2 production and the maturity parameters (soluble solids content and total acidity). Only in some cases 1-MCP generate a synergistic effect with the CA storage. The results of sensory analyses indicated that, the 1-MCP treatment did not affect the sweetness and whole fruit flavour while had a little effect on the decreasing cut fruit flavour. On the contrary the treated apple was more sour, crisp, firm and juicy. The effects of some treatment (dipping and MAP) on the nutrient stability were also investigated showing that in this case study the adopted treatments did not have drastic effects on the antioxidant compounds on the contrary the dipping may enhance the total antioxidant activity by the accumulation of ascorbic acid on the apple cut surface. Results concerning the effects of 1-MCP in combination with MAP on the quality parameters behaviour of the kiwifruit were not always consistent and clear: in terms of colour maintenance, it seemed to have a synergistic effect with N2O MAP; as far as ripening index is concerned, 1-MCP had a preservative effect, but just for sample packed in air.

Optimierung der Inhalationstherapie bei Kindern und Mukoviszidose-Patienten

Die pulmonale Applikation von Arzneimitteln hat in den vergangenen Jahren zu- rnnehmend an Bedeutung gewonnen und wird vor allem in der lokalen Therapie bei Asthma, COPD und Mukoviszidose genutzt. Als neues innovatives Inhalationsgerät befindet sich der Respimat® seit 2004 auf dem Arzneimittelmarkt und ist bisher nur für Erwachsene zugelassen. Daher wurden im Rahmen dieser Arbeit die Anwendbarkeit und die Modifikation des Respimats® bei Kindern untersucht. Zusammenfassend zeigen die Ergebnisse, dass Kinder ab einem Alter von fünf Jahren fähig sind suffizient mit dem Respimat® zu inhalieren und gute Werte für die estimierte Intrathorakaldosis zu erreichen. Besonders Kinder von 9-12 Jahren und Patienten mit DPI- oder Autohaler®-Inhalationserfahrung erreichten aufgrund eines hohen Atemflusses eine niedrigere estimierte Intrathorakaldosis als es das Potenzial des Respimats® erlaubt hätte. Durch den Einbau eines höheren internen Widerstands in den Orginalrespimat® wurde der Atemfluss signifikant verlangsamt und die Intrathorakaldosis erhöht. Des Weiteren wurden in der vorliegenden Arbeit die physikalisch-chemische Kompatibilität und die aerodynamischen Eigenschaften von Mischinhalationslösung/-suspensionen untersucht. In der Praxis mischen Muko-viszidose-Patienten oftmals mehrere Fertigarzneimittel und inhalieren diese simultan. Dadurch wird der Zeitaufwand der täglichen Inhalation reduziert und die Compliance sowie die Lebensqualität verbessert. Die 4er Kombination aus Colistimethat mit konservierungsmittelfreier Salbutamolsulfat, Ipratropiumbromidinhalationslösungen und Fluticason-17-propionatinhalationssuspension erwies sich als physikalisch-chemisch kompatibel. Die entwickelte mikrobiologische Wertbestimmungsmethode erwies sich als robust, präzise, gut reproduzierbar und erfüllte alle Anforderungen des statistischen Modells. Weiterhin wurden die aerodynamischen Eigenschaften einer praxisrelevanten 3er Mischinhalationssuspension aus Salbutamolsulfat, Ipratropiumbromid und Fluticason-17-propionat im Vergleich zu deren konsekutiven Vernebelung mittels Kaskadenimpaktion betrachtet. Die Charakteristik des erzeugten Aerosols änderte sich für simultan vernebeltes Salbutamolsulfat und Ipratropiumbromid nicht, wohingegen Fluticason-17-propionat bei simultaner Vernebelung eine Reduktion des MMADs, der delivered dose und der recovery aufwies. Dennoch ist die inhalative Glukokortikoiddosis ausreichend hoch um eine effektive antiinflammatorische Wirkung zu gewährleisten. Daher kann die simultane Inhalation der 3er Kombination empfohlen werden und somit die Compliance und die Lebensqualität von Mukoviszidosepatienten erhöht werden.rn

Pi-konjugierte Plasmapolymere als organische Halbleiter durch vorstrukturierte single-source-Precursoren

Die vorliegende Arbeit behandelt die Entwicklung einer neuartigen Synthesestrategie von π-konjugierten Plasmapolymeren durch die Anwendung von vorstrukturierten aromatischen Precursoren und gepulsten Niederdruckplasmen. Es gelang erstmals die strukturtreue Synthese von π-konjugierten organischen Plasmapolymeren mit dem vollkommenen Erhalt der aromatischen Funktionalität und der selektiven para-Verknüpfung aromatischer Einheiten durch geeignete Heteroatome. Hierbei kamen 1,4-Dithiophenol zur Synthese von Plasmapoly(p-phenylensulfid) und 4-Iodanilin zur Synthese von Plasmapolyanilin zur Anwendung. Die mit hoher Präzision abgeschiedenen Filme konnten sowohl postsynthetisch als auch in situ p-dotiert werden. Die chemischen Strukturen sowie deren physikalisch-chemischen Eigenschaften konnten vor allem mittels Röntgenphotoelektronen-, UV-VIS-NIR-, IR-, NMR-, ESR- und Impedanz-Spektroskopie aufgeklärt werden. Die synthetisierten dotierten Plasmapolymere zeigten eindeutig ohmsche Leistungsmechanismen, teilweise mit einer Leitfähigkeitserhöhung von bis zu 8 Dekaden gegenüber dem undotierten konventionellen Polymer.

Proteomic analysis of ocular surface components by use of HPLC based mass spectrometric strategies

In der vorliegenden Arbeit wurde eine Top Down (TD) und zwei Bottom Up (BU) MALDI/ESI Massenspektrometrie/HPLC-Methoden entwickelt mit dem Ziel Augenoberfächenkomponenten, d.h. Tränenfilm und Konjunktivalzellen zu analysieren. Dabei wurde ein detaillierter Einblick in die Entwicklungsschritte gegeben und die Ansätze auf Eignung und methodische Grenzen untersucht. Während der TD Ansatz vorwiegend Eignung zur Analyse von rohen, weitgehend unbearbeiteten Zellproben fand, konnten mittels des BU Ansatzes bearbeitete konjunktivale Zellen, aber auch Tränenfilm mit hoher Sensitivität und Genauigkeit proteomisch analysiert werden. Dabei konnten mittels LC MALDI BU-Methode mehr als 200 Tränenproteine und mittels der LC ESI Methode mehr als 1000 Tränen- sowie konjunktivale Zellproteine gelistet werden. Dabei unterschieden sich ESI- and MALDI- Methoden deutlich bezüglich der Quantität und Qualität der Ergebnisse, weshalb differente proteomische Anwendungsgebiete der beiden Methoden vorgeschlagen wurden. Weiterhin konnten mittels der entwickelten LC MALDI/ESI BU Plattform, basierend auf den Vorteilen gegenüber dem TD Ansatz, therapeutische Einflüsse auf die Augenoberfläche mit Fokus auf die topische Anwendung von Taurin sowie Taflotan® sine, untersucht werden. Für Taurin konnten entzündungshemmende Effekte, belegt durch dynamische Veränderungen des Tränenfilms, dokumentiert werden. Außerdem konnten vorteilhafte, konzentrationsabhängige Wirkweisen auch in Studien an konjunktival Zellen gezeigt werden. Für die Anwendung von konservierungsmittelfreien Taflotan® sine, konnte mittels LC ESI BU Analyse eine Regenerierung der Augenoberfläche in Patienten mit Primärem Offenwinkel Glaukom (POWG), welche unter einem “Trockenem Auge“ litten nach einem therapeutischen Wechsel von Xalatan® basierend auf dynamischen Tränenproteomveränderungen gezeigt werden. Die Ergebnisse konnten mittels Microarray (MA) Analysen bestätigt werden. Sowohl in den Taurin Studien, als auch in der Taflotan® sine Studie, konnten charakteristische Proteine der Augenoberfläche dokumentiert werden, welche eine objektive Bewertung des Gesundheitszustandes der Augenoberfläche ermöglichen. Eine Kombination von Taflotan® sine und Taurin wurde als mögliche Strategie zur Therapie des Trockenen Auges bei POWG Patienten vorgeschlagen und diskutiert.

Retinal vascular occlusion after vitrectomy with retrobulbar anesthesia-observational case series and survey of literature

BACKGROUND: Severe postoperative loss of vision has been occasionally reported as a rare complication of retrobulbar anesthesia, and several possible causes have been proposed in the literature. In this work, our own and other investigators' experiences with these complications are surveyed with a view to identifying its pathophysiology. PATIENTS: This observational case series refers to six patients who presented during a 3-month period with occlusion of either the central artery itself (n = 3) or a branch thereof (n = 3) 2-14 days after uneventful vitreoretinal surgery following retrobulbar anesthesia with a commercial preparation of mepivacaine (1% Scandicain®, Astra Chemicals, Sweden) containing methyl- and propyl parahydroxybenzoate as preservatives. RESULTS: Three of the patients carried risk factors, which were medically controlled. In three individuals, vasoocclusion was observed after a second vitreoretinal intervention, which was performed 3-12 months after uneventful primary surgery. Good visual recovery was observed in only one instance. CONCLUSIONS: In patients who were anesthetized with preservative-free mepivacaine, no vasoocclusion occurred. In individuals who were anesthetized with mepivacaine containing the preservatives methyl- and propyl parahydroxybenzoate, a tenfold increase in the incidence of eyes requiring re-operation was documented, with a 2- to 14-day lapse in the onset of vasoocclusion. These findings reveal a possible implication of preservatives contained in the local anesthetic solution for the vasoocclusive events. Due to this potential hazard, the use of preservative-free preparations of local anesthesia in ocular surgery is emphasized in order to prevent this sight-threatening complication.

[Prosthetic rehabilitation of a traumatic occlusion due to bulimia nervosa. Case report]

Because of the typical localisation of erosions in anorectic/bulimic patients, the dentist is frequently the first medical person to discern this general illness (anorexia and bulimia nervosa). From the dental viewpoint, the aim should be to preserve sound dental tissue and to prevent further toothwear. A restorative treatment is to be carried out only after causal therapy and after resolving the basic disease. By means of this procedure a good long-term prognosis can be expected. Considering the patient's young age, dentistry should be preservative using the adhesive technique. This case report documents the systematic procedure of the functional and esthetic rehabilitation of an eroded dentition and shows factors essential to the treatment.

Safety, tolerability, and efficacy of fixed combination therapy with dorzolamide hydrochloride 2% and timolol maleate 0.5% in glaucoma and ocular hypertension.

Glaucoma is a collection of diseases characterized by multifactorial progressive changes leading to visual field loss and optic neuropathy most frequently due to elevated intraocular pressure (IOP). The goal of treatment is the lowering of the IOP to prevent additional optic nerve damage. Treatment usually begins with topical pharmacological agents as monotherapy, progresses to combination therapy with agents from up to 4 different classes of IOP-lowering medications, and then proceeds to laser or incisional surgical modalities for refractory cases. The fixed combination therapy with the carbonic anhydrase inhibitor dorzolamide hydrochloride 2% and the beta blocker timolol maleate 0.5% is now available in a generic formulation for the treatment of patients who have not responded sufficiently to monotherapy with beta adrenergic blockers. In pre- and postmarketing clinical studies, the fixed combination dorzolamide-timolol has been shown to be safe and efficacious, and well tolerated by patients. The fixed combination dorzolamide-timolol is convenient for patients, reduces their dosing regimen with the goal of increasing their compliance, reduces the effects of "washout" when instilling multiple drops, and reduces the preservative burden by reducing the number of drops administered per day.

Kant y la modernidad : un enfoque desde el trabajo social

En el trabajo se pretende analizar las principales categorías sobre las que se fundamenta la modernidad, a través del pensamiento de Kant. El núcleo del proyecto moderno es la idea de universalidad, individualidad y autonomía, que junto a la distinción entre hombre y Naturaleza y su interrelación, dan origen a la perspectiva de la razón emancipadora. Los debates filosóficos de la época incorporaron una mirada sobre los problemas sociales y resultan de singular importancia para demostrar que el Trabajo Social en su origen tuvo un claro carácter antimoderno. Las primeras organizaciones donde encontramos los antecedentes de la profesión avanzan con un carácter conservador, mediado por una alianza entre burguesía, iglesia y estado, aceptando el modo capitalista de producción y de pensar a través de prácticas tutelares, disciplinarias y moralizantes que aún perduran en la actualidad y que se alejan del pensamiento originario de Kant.

Sediment Trap Data from the CARIACO Ocean Time Series (1995-2010)

The Cariaco Basin is a 1400-m-deep depression approximately 160 km long by 70 km wide located off the central Venezuelan coast . It is connected to the Atlantic Ocean by a sill ~100-m-deep, and two slightly deeper channels that breech it; Canal Centinela (146-m-deep) and Canal de la Tortuge (135-m-deep). High surface production rates and restricted circulation result in anoxic waters below ca. 275 m. The depth of the oxycline varies between 250 and 320 m and is independent of density. Rather, fluctuations in oxycline depth appear to be due to lateral intrusions of Caribbean Sea water that are linked to eddies along the continental shelf. A mooring with five sediment traps (Z, A-D) is located in the eastern Cariaco Basin. Traps A-D have been in place since November 1995. Trap A is located in oxic waters at 226 ± 6 m. Trap B is located at 407 ± 3 m and Trap D is located at 1205 ± 3 m. Trap C was located at a depth of 880 ± 2 m from Jan. 1996 to Nov. 2000, and was moved to 807 ± 2 m in Nov. 2000. A fifth trap, Z, was added in November 2003 at 110 m for the first 6 months, and at 150 m thereafter. All five sediment traps are coneshaped with a 0.5 m**2 opening that is covered with a baffle top to reduce turbulence. The mooring is deployed for six-month intervals and each sample collection cup is filled with a buffered 3.2% formalin solution as a preservative for the accumulating organic matter. The cups are numbered 1-13, with cup 1 collecting for the two-week interval immediately following deployment, and cup 13 collecting for the 2 weeks immediately before recovery.

Detection of Biological CO2 and 1,3-Pentadiene Using Non-refrigerated Low-Cost MWIR Detectors

The early detection of spoiling metabolic products in contaminated food is a very important tool to control quality. Some volatile compounds produce unpleasant odours at very low concentrations, making their early detection very challenging. This is the case of 1,3-pentadiene produced by microorganisms through decarboxylation of the preservative sorbate. In this work, we have developed a methodology to use the data produced by a low-cost, compact MWIR (Mid-Wave IR) spectrometry device without moving parts, which is based on a linear array of 128 elements of VPD PbSe coupled to a linear variable filter (LVF) working in the spectral range between 3 and 4.6 ?m. This device is able to analyze food headspace gases through dedicated sample presentation setup. This methodology enables the detection of CO2 and the volatile compound 1,3-pentadiene, as compared to synthetic patrons. Data analysis is based on an automated multidimensional dynamic processing of the MWIR spectra. Principal component and discriminant analysis allow segregating between four yeast strains including producers and no producers. The segregation power is accounted as a measure of the discrimination quality.

CONHECIMENTOS E PREVENÇÃO DE DST/AIDS EM ADOLESCENTES

A Psicologia da Saúde vem se desdobrando para atender a demanda da saúde pública, principalmente sobre prevenção de doenças e promoção da saúde. No que se refere a epidemia da AIDS e outras doenças sexualmente transmissíveis, o adolescente tem sido o público mais vulnerável. A adolescência é considerada uma fase perturbada e perturbadora. Nesse período da vida o adolescente está mais sujeito à contaminação das DST/AIDS em razão da instabilidade emocional e sua postura frente a valores e padrões de conduta. Este estudo tem por objetivo descrever conhecimentos e comportamentos de proteção e risco de práticas sexuais de adolescentes; descrever dados sócio-econômicos e demográficos desses adolescentes, descrever o conhecimento dos adolescentes em relação as DST/AIDS e descrever os comportamentos de proteção e riscos a respeito das DST/AIDS. A população deste estudo foi constituída por 95 adolescentes de ambos os gêneros, com um predomínio do gênero masculino, faixa etária entre 14 e 21 anos e com renda familiar média de 4 (quatro) salários mínimos. Trata-se de pesquisa descritiva, para o qual utilizou-se um questionário de autopreenchimento composto por questões norteadas ao tema. A coleta de dados ocorreu em sala de aula no período noturno, de uma escola estadual do município de Guarulhos. Após o término do preenchimento do questionário, os adolescentes assistiram uma palestra de prevenção e orientação sobre DST/AIDS, onde elucidaram dúvidas. Os resultados demonstram 67,4% dos adolescentes, tanto o gênero feminino quanto o gênero masculino, tem dificuldades de definir o conceito de sexualidade e 84,2% sabem corretamente a definição de doenças sexualmente transmissíveis. A maioria dos adolescentes (67,4%) respondeu conhecer algum tipo de doença sexualmente transmissível, destacando-se aqui a AIDS e a gonorréia. O gênero masculino teve início da vida sexual aos 10 anos e o gênero feminino aos 13 anos, representando 53,7% com vida sexual ativa. Neste estudo 58,9% informam saber quais são os comportamentos de proteção, porém entre estes, apenas 55,8% utilizam o preservativo masculino (camisinha). Não há diferenças significativas quanto à modalidade de relacionamento e o uso constante do preservativo masculino. Verificou-se que 63,1% dos adolescentes obtém informações e conhecimentos sobre as DST/AIDS através dos profissionais da educação e da saúde. Portanto, a sala de aula passa a ser um fator de proteção. Esse estudo confirma que parte dos adolescentes tem conhecimento e informações sobre conceitos relativos as DST/AIDS, porém quanto às práticas para um comportamento de proteção frente às mesmas apresentam conhecimentos frágeis, gerando assim comportamentos de risco. Estas situações comprometem a tomada de comportamentos de proteção. Portanto, um programa contínuo da área da saúde e da educação dentro da escola que desenvolva atividades interativas a fim de transformar o comportamento do adolescente sobre informações e conhecimentos em consciência de comportamentos de proteção efetivas poderá melhorar essa relação entre ter o conhecimento e utilizá-lo na prática.(AU)

CONHECIMENTOS E PREVENÇÃO DE DST/AIDS EM ADOLESCENTES

A Psicologia da Saúde vem se desdobrando para atender a demanda da saúde pública, principalmente sobre prevenção de doenças e promoção da saúde. No que se refere a epidemia da AIDS e outras doenças sexualmente transmissíveis, o adolescente tem sido o público mais vulnerável. A adolescência é considerada uma fase perturbada e perturbadora. Nesse período da vida o adolescente está mais sujeito à contaminação das DST/AIDS em razão da instabilidade emocional e sua postura frente a valores e padrões de conduta. Este estudo tem por objetivo descrever conhecimentos e comportamentos de proteção e risco de práticas sexuais de adolescentes; descrever dados sócio-econômicos e demográficos desses adolescentes, descrever o conhecimento dos adolescentes em relação as DST/AIDS e descrever os comportamentos de proteção e riscos a respeito das DST/AIDS. A população deste estudo foi constituída por 95 adolescentes de ambos os gêneros, com um predomínio do gênero masculino, faixa etária entre 14 e 21 anos e com renda familiar média de 4 (quatro) salários mínimos. Trata-se de pesquisa descritiva, para o qual utilizou-se um questionário de autopreenchimento composto por questões norteadas ao tema. A coleta de dados ocorreu em sala de aula no período noturno, de uma escola estadual do município de Guarulhos. Após o término do preenchimento do questionário, os adolescentes assistiram uma palestra de prevenção e orientação sobre DST/AIDS, onde elucidaram dúvidas. Os resultados demonstram 67,4% dos adolescentes, tanto o gênero feminino quanto o gênero masculino, tem dificuldades de definir o conceito de sexualidade e 84,2% sabem corretamente a definição de doenças sexualmente transmissíveis. A maioria dos adolescentes (67,4%) respondeu conhecer algum tipo de doença sexualmente transmissível, destacando-se aqui a AIDS e a gonorréia. O gênero masculino teve início da vida sexual aos 10 anos e o gênero feminino aos 13 anos, representando 53,7% com vida sexual ativa. Neste estudo 58,9% informam saber quais são os comportamentos de proteção, porém entre estes, apenas 55,8% utilizam o preservativo masculino (camisinha). Não há diferenças significativas quanto à modalidade de relacionamento e o uso constante do preservativo masculino. Verificou-se que 63,1% dos adolescentes obtém informações e conhecimentos sobre as DST/AIDS através dos profissionais da educação e da saúde. Portanto, a sala de aula passa a ser um fator de proteção. Esse estudo confirma que parte dos adolescentes tem conhecimento e informações sobre conceitos relativos as DST/AIDS, porém quanto às práticas para um comportamento de proteção frente às mesmas apresentam conhecimentos frágeis, gerando assim comportamentos de risco. Estas situações comprometem a tomada de comportamentos de proteção. Portanto, um programa contínuo da área da saúde e da educação dentro da escola que desenvolva atividades interativas a fim de transformar o comportamento do adolescente sobre informações e conhecimentos em consciência de comportamentos de proteção efetivas poderá melhorar essa relação entre ter o conhecimento e utilizá-lo na prática.(AU)

The interesting narrative of the life of Olaudah Equiano; or Gustavus Vassa, the African. /

Text continuous (despite pagination).

The decomposition of starch grains in soils: implications for archaeological residue analyses

Recent research involving starch grains recovered from archaeological contexts has highlighted the need for a review of the mechanisms and consequences of starch degradation specifically relevant to archaeology. This paper presents a review of the plant physiological and soil biochemical literature pertinent to the archaeological investigation of starch grains found as residues on artefacts and in archaeological sediments. Preservative and destructive factors affecting starch survival, including enzymes, clays, metals and soil properties, as well as differential degradation of starches of varying sizes and amylose content, were considered. The synthesis and character of chloroplast-formed 'transitory' starch grains, and the differentiation of these from 'storage' starches formed in tubers and seeds were also addressed. Findings of the review include the higher susceptibility of small starch grains to biotic degradation, and that protective mechanisms are provided to starch by both soil aggregates and artefact surfaces. These findings suggest that current reasoning which equates higher numbers of starch grains on an artefact than in associated sediments with the use of the artefact for processing starchy plants needs to be reconsidered. It is argued that an increased understanding of starch decomposition processes is necessary to accurately reconstruct both archaeological activities involving starchy plants and environmental change investigated through starch analysis. (C) 2004 Elsevier Ltd. All rights reserved.