Hepatitis E, Helicobacter pylori, and gastrointestinal symptoms in workers exposed to waste water

BACKGROUND

Workers exposed to sewage may have an increased risk of infection by Helicobacter pylori and hepatitis E virus (HEV).

AIMS

To assess the prevalence of clinical hepatitis E (HE) and peptic ulcer disease as well as the seroprevalence of antibodies to H pylori and HEV in workers with and without sewage exposure and to look for symptoms due to exposure to endotoxin.

METHODS

In the first year of a prospective cohort study 349 sewage exposed workers and 429 municipal manual workers (participation: 61%) underwent a complete medical examination. Travelling to endemic areas, socioeconomic level, age, country in which childhood was spent, and number of siblings were considered as the main confounding factors.

RESULTS

Peptic ulcer disease and clinical HE did not occur more often in workers exposed to sewage. Prevalence of antibodies to HEV was 3.3% and overall prevalence of IgG antibodies to H pylori was 42% with large differences between subgroups. Logistic regression did not show an increased risk of seropositivity or antibodies to parietal cells in sewage exposed workers, but disentangling the effect of exposure from that of confounders was extremely difficult. No increase of symptoms due to exposure to endotoxin was found in sewage workers, with the exception of diarrhoea.

CONCLUSIONS

No clear increased risk of infection by H pylori or by HEV in workers exposed to sewage was found in this cross-sectional study, but these results need to be confirmed by follow up.

Protection by pentoxifylline against graft failure from storage injury after orthotopic rat liver transplantation with arterialization

Destruction of the endothelial cell lining and activation of Kupffer cells after reperfusion limits the safe storage of livers for transplantation surgery. Tumor necrosis factor-alpha (TNF) release by activated Kupffer cells may contribute to graft failure from storage injury. Accordingly, we evaluated whether pentoxifylline, which suppresses macrophage TNF release, would improve graft survival after orthotopic rat liver transplantation with arterialization. Livers from syngeneic Lewis rats were stored for 12-24 h in cold UW solution. Prior to implantation, the livers were flushed with cold Ringer's solution or warm Carolina rinse solution B. With either rinse, pentoxifylline treatment of graft recipients significantly improved graft survival. Combined use of pentoxifylline (50 mg/kg for 5 days) and Carolina rinse solution doubled the safe storage time to 24 h. Acidotic pH and antioxidants were essential components of Carolina rinse solution that acted synergistically with pentoxifylline. Pentoxifylline was also shown to suppress TNF release by lipopolysaccharide (LPS)-stimulated cultured rat Kupffer cells. Thus, pentoxifylline may protect against primary non-function and failure of grafts from storage injury by suppressing excessive TNF release by activated Kupffer cells. However, neutralization of TNF with excess anti-TNF antibody did not improve survival. This may mean that depletion of TNF is as deleterious as excess TNF production. Alternatively, other Kupffer cell secretions [e.g., interleukin-1 (IL-1), interleukin-6 (IL-6) and other cytokines] may be involved in the pathogenesis of graft failure. In conclusion, pentoxifylline could protect against graft failure from storage injury.

Travel health insurance: indicator of serious travel health risks

BACKGROUND

Travel health risks documented by questionnaire surveys obtained (e.g., during homebound flights) are incomplete since they miss most patients who need to be repatriated.

METHODS

All patient claim files were reviewed from 1997 to 1998, of the largest Swiss travel insurance company.

RESULTS

Among 242 claims, 69.4% were due to illness, 30.6% due to accidents; infections were the most frequent illnesses, the extremities were the most frequently traumatized part of the body. Although the illness-to-accident ratio was 1:5 in industrialized countries and the Caribbean, it exceeded 3:0 in some developing regions. Accident proneness was noted in the first week abroad.

CONCLUSION

Even if no denominator data are available, this analysis offers an insight in travel health risks, allowing comparison of the occurrences of very different, serious, health problems abroad.

[Hepatitis E and exposure to waste water]

Hepatitis E virus (HEV) is found in waste water which represents a route of infection. However, the risk for sewage workers is unknown. Thus, we aimed at determining the prevalence of anti-HEV antibodies in sewage workers from the Canton of Zurich. The anti-HEV antibodies evaluated in 288 subjects with exposure to sewage and 306 controls, a total of 594 subjects. Overall, twenty-two (3.7%) subjects had anti-HEV, the seroprevalence was similar in those exposed and controls. The most important risk factor, travelling in endemic areas, was lacking in two workers, who both were exposed to sewage. A follow up study in the population will soon give further evidence on the incidence rate.

Prevalence of Tropheryma whipplei DNA in patients with various gastrointestinal diseases and in healthy controls

BACKGROUND

Little is known about the epidemiology of Tropheryma whipplei and its prevalence in people without clinical signs of Whipple's disease.

PATIENTS AND METHODS

We screened 239 patients with various gastrointestinal diseases for T. whipplei DNA and compared them with 215 healthy controls in order to check whether T. whipplei might be a risk factor for common gastrointestinal problems or diseases. We detected the 16S rDNA of T. whipplei in salivary and stool samples using a specific seminested PCR.

RESULTS

The prevalence of T. whipplei DNA in patients and in controls was 4.2% (95% CI 2.0-7.6% ) and 7.0% (95% CI 4.0-11.3%), respectively. None of the different gastrointestinal diseases was associated with a higher rate of PCR-positive tests, except for the group of patients with reflux syndrome. Five out of 43 patients with reflux were found to be positive, with all five being positive in the salivary sample. This is in contrast to our findings in carriers without reflux with mainly positive stool samples (p < 0.01).

CONCLUSION

We conclude that the asymptomatic carrier state of T. whipplei indeed exists and that it is much more frequent than the rare Whipple's disease. The higher prevalence of T. whipplei DNA in the saliva of patients with reflux syndrome suggests that the stomach might be the habitat of the organism.

[Complications after total knee arthroplasty]

Complications after total knee arthroplasty were evaluated prospectively after a total of 321 procedures. 53 (16.5 %) patients showed postoperative courses deviating from the routine. Of these 5.0 % developed clinically relevant deep vein thromboses, the rate of deep infections was 1.6 %, 3.7 % of the patients suffered from persisting or recurrent joint effusions, arthrofibrosis was observed in 4.4 % of the patients and 1.9 % were affected by wound complications. In most patients deep infections were treated by removal of the implants and reimplantation after clearing of the infection. The primary treatment of arthrofibrosis consisted of manipulation under general or regional anaesthesia. Patients with recurrent joint effusions received punctions, which had to be repeated in some cases. In one patient an intraarticular drainage had to be inserted. The conservative or surgical therapy of wound complications depended on the patient's situation. In patients with thrombosis distal to the trifurcation of the popliteal vein anticoagulation with heparin was continued. In contrast, in patients with femoral or popliteal venous thrombosis the anticoagulation was changed to cumarine derivates.

[Biomechanical study on lumbar spondylodeses using an internal fixateur consisting of a titanium alloy]

OBJECTIVE

Biomechanical properties of an internal fixateur manufactured of a titanium alloy (Ti-6Al-4V-alloy) to be evaluated in an in vitro setting.

METHOD

Internal fixateurs were inserted into six (four female and two male specimens) human lumar spine segments L2 to L4. Only dorsal instrumentations were performed. Physiological loads were applied (2.0 to 10.0 Nm for torque, 2.0 to 7.5 Nm for extension/flexion and lateral bending). Biomechanical investigations were performed in four settings: Intact specimen without instrumentation, instrumented specimen, instrumented specimen after corpectomy of the middle vertebral body, instrumented specimen after corpectomy of the middle vertebral body with an additional transverse connector.

RESULTS

Stability after instrumentation was increased by 84.7 % for flexion/extension, by 78.2 % for lateral bending and by 43 % for axial torsion. Axial torsion was already less distinct in the physiological specimen. The stability of instrumented specimen after corpectomy was superior to that of intact vertebral segments without internal fixation. Additional application of transverse connectors did not significantly enhance the stiffness of the implant.

CONCLUSION

For the clinical use there is no difference in the biomechanical properties of the titanium fixateur compared to similar constructions made of stainless steel. The possibility of performing MRI- or CT-scans after implantation of titanium implants is a main clinical advantage. The stabilisation after corpectomy is remarkable, so that a sufficient fracture-stabilisation is possible. Based on the data, the application of transverse connectors cannot be recommended.

Hepatitis A in workers exposed to sewage: a systematic review

OBJECTIVES

To assess whether the scientific literature supports the hypothesis that workers exposed to sewage are at higher risk of hepatitis A (HA).

METHODS

All original papers reporting epidemiological studies published in English, French, or German which reported on the risk of HA infection in workers exposed to sewage were eligible. They were identified by several methods and each original paper was assessed independently with a checklist by two people. Studies were classified according to the strength of their design. Non-eligible studies were also examined to assess the impact of publication bias. If the risk estimates diverged widely, causes for heterogeneity were assessed. A distinction was made between seroprevalence studies based on subclinical HA (defined only by the presence of anti-HA antibodies) and clinical HA.

RESULTS

17 eligible studies were identified. No indication of an increased risk of clinical HA could be found. For seroprevalence the studies with the strongest design suggested a slightly increased risk of subclinical HA with an odds ratio (OR) <2.5. Heterogeneity was considerable and precluded a meta-analysis. Considering non-eligible studies would still decrease the OR.

CONCLUSIONS

The systematic review does not confirm an increased risk of clinical HA in workers exposed to sewage. An increased risk of subclinical HA cannot be excluded but the association between seropositivity and exposure to sewage was not strong and became still weaker if publication bias was taken into account.

Five-year results from chemonucleolysis with chymopapain or collagenase: a prospective randomized study

STUDY DESIGN

A 5-year clinical follow-up assessment of a prospective randomized study of chemonucleolysis using chymopapain (4000 IU) or collagenase (400 ABC units) was performed.

SUMMARY OF BACKGROUND DATA

Intradiscal therapy can be performed for patients with contained discs by chemonucleolysis, percutaneous discectomy, or laser ablation. The oldest intradiscal therapy is chemonucleolysis with chymopapain.

OBJECTIVE

The purpose of this study was to compare prospectively the efficacy of chymopapain and collagenase for intradiscal injection.

METHODS

In this study, 100 patients with indication for intradiscal therapy were prospectively randomized to treatment with either chymopapain or collagenase. All the injections were performed by the double-needle technique with the patient under general anesthesia. The mean age of the patients was 35.5 years in the chymopapain group and 38 years in the collagenase group. An equal number of injections was performed at L4-L5 and L5-S1.

RESULTS

After 5 years, good and excellent results were observed in 72% of the chymopapain group and 52% of the collagenase group when the surgically treated and lost patients were graded as poor. Using a scale of 0 (no pain) to 10 (intractable pain), the pain level dropped from 8.5 to 0.7 in the chymopapain group and from 8.6 to 0.9 in the collagenase group. Microdiscectomy at the injected level was required for 23 patients (14 in the collagenase group and 9 in the chymopapain group).

CONCLUSIONS

After 5 years, no deterioration had occurred, as compared with the 1-year follow-up assessment. Chymopapain has proved to be safe, with one minor anaphylactic reaction, and effective even over the long term. Collagenase may need further study and cannot be recommended at this time.

Effectiveness and tolerability of melatonin and zolpidem for the alleviation of jet lag

BACKGROUND

The aim of this study was to compare the effectiveness and tolerability of a chronobiotic (melatonin) with a hypnotic (zolpidem) and the combination of both substances to alleviate jet lag symptoms associated with eastward travel.

METHODS

This double-blind, randomized, placebo-controlled study is based on 137 volunteers flying from Switzerland to the American continent and back (6-9 time zones). The participants either received melatonin 5 mg (n = 35), zolpidem 10 mg (n = 34), a combination thereof (n = 29) or placebo (n = 39) on the eastbound flight back to Switzerland and once daily at bedtime on 4 consecutive days after the flight. The test battery included daily sleep logs, symptoms questionnaires, and the Profile of Mood States (POMS). Also, on the last treatment day, Visual Analog Scales (VAS) were completed to assess overall jet lag ratings and treatment effectiveness. Baseline data were collected on 4 consecutive days 2 wk after the flight. During post-flight treatment and baseline, motor activity was assessed in a subgroup of 49 subjects using wrist-worn ambulatory monitors.

RESULTS

The self-rated sleep quality was significantly improved by zolpidem, especially during the night flight. Subjects taking zolpidem reported significantly less jet lag and zolpidem was rated as the most effective jet lag medication. However, zolpidem and the combination melatonin/zolpidem were less well tolerated than melatonin alone; adverse event reports included nausea, vomiting, amnesia and somnambulia to the point of incapacitation. Confusion, morning sleepiness and nausea were highest in the combination group.

CONCLUSIONS

All active treatments led to a decrease of jet lag severity with zolpidem being the most effective treatment, particularly in facilitating sleep on night flights. Potential individual adverse reactions to this hypnotic have to be considered.

Suppression of allograft rejection in the sponge Suberites domuncula by FK506 and expression of genes encoding FK506-binding proteins in allografts

Porifera (sponges) are, evolutionarily, the oldest metazoan phylum. Recent molecular data suggest that these animals possess molecules similar to and homologous with those of the innate and adaptive immune systems of higher Metazoa. Applying the biological system of parabiosis and the technique of differential display of mRNA, two cDNAs encoding putative FK506-binding proteins were isolated. FK506 is successfully used in clinics as a drug to prevent allograft rejection and is toxic to Suberites domuncula cells in vitro at doses above 100ng ml−1. Autograft fusion of transplants from S. domuncula was not affected by FK506. Allograft non-fusion was not affected by FK506 at toxic doses; however, at the non-toxic dose of 20ng ml−1, the allografts fused with each other. It is shown that at the attachment zone in untreated and (particularly drastic) in FK506-treated allografts, expression of the genes encoding the FK506-binding proteins is upregulated. These data indicate that the drug FK506 suppresses allograft rejection in S. domuncula, most probably via interaction with expression of the gene coding for the FK506-binding proteins.

EnteroaggregativeEscherichia colias a Major Etiologic Agent in Traveler's Diarrhea in 3 Regions of the World

Enteroaggregative Escherichia coli (EAEC) has been reported to cause traveler's diarrhea and persistent diarrhea in children in developing countries and in immunocompromised patients. To clarify the prevalence of EAEC in traveler's diarrhea, we studied 636 US, Canadian, or European travelers with diarrhea: 218 in Guadalajara, Mexico (June--August 1997 and 1998), 125 in Ocho Rios, Jamaica (September 1997--May 1998), and 293 in Goa, India (January 1997--April 1997 and October 1997--February 1998). Stool samples were tested for conventional enteropathogens. EAEC strains were identified by use of the HEp-2 assay. EAEC was isolated in 26% of cases of traveler's diarrhea (ranging from 19% in Goa to 33% in Guadalajara) and was second only to enterotoxigenic E. coli as the most common enteropathogen in all areas. Identification of EAEC reduced the number of cases for which the pathogen was unknown from 327 (51%) to 237 (37%) and explained 28% of cases with unknown etiology. EAEC was a major cause of traveler's diarrhea in 3 geographically distinct study areas.

[Malaria--chemoprophylaxis 2001]

An estimated 20,000 to 30,000 cases of imported malaria are annually diagnosed in industrialised countries. Some 700 of them concern Swiss travellers and foreign guests. Exposure prophylaxis and chemoprophylaxis for high risk destinations lower the risk of malarial disease. The latter is defined as regular intake of antimalarial drugs in subtherapeutic dosage in order to suppress the development of clinical disease. Drugs are usually taken from one week before travel until four weeks after return from an endemic area. Mefloquine, doxycycline, chloroquine plus proguanil, and presumably soon also atovaquone plus proguanil are available in Switzerland for chemoprophylaxis.

[Vaccinations for overseas travelers--new evidence and recommendations]

Vaccinations are an easy and highly effective way to keep travellers healthy. There are few problems with compliance, as all vaccinations are administered pretravel and many vaccines offer protection rates > 95% after a single dose (e.g. hepatitis A, yellow fever). Vaccination of hepatitis A and diphtheriatetanus are recommended for all developing countries. Polio is still indicated for Asia and Africa. Hepatitis B, if possible in combination with A, is recommended for persons travelling for > 30 days, travellers < 35 years, and for people showing special risk behaviour (e.g. high-risk sports, unprotected sexual intercourse). Depending on destination and kind and duration of travel, further vaccinations have to be considered, e.g.: yellow fever (endemic areas, rule of entry), rabies (trekking, travel in remote areas), typhoid fever (Indian sub-continent), meningococcal meningitis (meningitis belt, pilgrims to Saudi-Arabia), tick-borne encephalitis (endemic areas in Europe and Asia), influenza (persons at special risk of complications), Japanese encephalitis (low standard travel in rural areas of Southeast Asia > 30 days), measles (particularly endemic in Africa). Cholera vaccination is virtually never indicated. Several vaccines can be delivered at the same time.

Guidelines for adults on self-medication for the treatment of acute diarrhoea

Acute uncomplicated diarrhoea is commonly treated by self-medication. Guidelines for treatment exist, but are inconsistent, sometimes contradictory, and often owe more to dogma than evidence. An ad hoc multidisciplinary group has reviewed the literature to determine best practice. In general it is recognized that treatment of acute episodes relieves discomfort and social dysfunction. There is no evidence that it prolongs the illness. Self-medication in otherwise healthy adults is safe. Oral loperamide is the treatment of choice. Older anti-diarrhoeal drugs are also effective in the relief of symptoms but carry the risk of unwanted adverse effects. Oral rehydration solutions do not relieve diarrhoea, and confer no added benefit for adults who can maintain their fluid intake. Probiotic agents are, at present, limited in efficacy and availability. Antimicrobial drugs, available without prescription in some countries, are not generally appropriate for self-medication, except for travellers on the basis of medical advice prior to departure. Medical intervention is recommended for the management of acute diarrhoea in the frail, the elderly (> 75 years), persons with concurrent chronic disease, and children. Medical intervention is also required when there is no abatement of the symptoms after 48 h, or when there is evidence of deterioration such as dehydration, abdominal distension, or the onset of dysentery (pyrexia > 38.5 degrees C and/or bloody stools).

Surgical or conservative treatment for chronic rotator cuff calcifying tendinitis--a matched-pair analysis of 100 patients

Conservative or operative treatment for rotator cuff calcifying tendinitis was investigated in 100 patients in a matched-pair analysis. They were examined clinically and ultrasonographically 35-60 months after the initial visit. The mean Patte score was 91.8 for the patients who underwent surgical treatment and 81 for the ones who received conservative therapy (p < 0.004), while the age-related Constant-score was 103.4 and 95, respectively. Ultrasonography showed 28% calcifications in the surgical group, 18% newly formed and 10% that did not resolve after surgery. In the conservatively treated group, 33% calcifications were seen, of which 67% resolved. The number of rotator cuff ruptures was significantly higher in the conservative group. In the surgical group, 2% of partial tears and in the conservative group 5% of partial and 4% of complete cuff ruptures were found. Conservative treatment for calcifying tendinitis leads to less favourable pain results in the long term than surgical treatment. Surgery shortens the painful period and may reduce the number of future rotator cuff ruptures. Finally, the subjective functional outcome is significantly better after surgery.

Time-resolved monitoring of flash-induced changes of fluorescence quantum yield and decay of delayed light emission in oxygen-evolving photosynthetic organisms

The present contribution describes a new experimental setup that permits time-resolved monitoring of the rise kinetics of the relative fluorescence yield, Phi(rel)(t), and simultaneously of the decay of delayed light emission, L(t), induced by strong actinic laser flashes. The results obtained by excitation of dark-adapted samples with a train of eight flashes reveal (a) in suspensions of spinach thylakoids, Phi(rel)(t) exhibits a typical period four oscillation that is characteristic for a dependence on the redox states S(i)() of the water oxidizing complex (WOC), (b) the relative extent of the unresolved "instantaneous" rise to the level (100 ns) at 100 ns and the maximum values of Phi(rel)(t) attained at about 45 s after each actinic flash, (45 s) synchronously oscillate and exhibit the largest values at flash nos. 1 and 5 and minima after flash nos. 2 and 3, (c) opposite effects are observed for the normalized extent of the rise kinetics in the 100 ns to 5 s time domain of relative fluorescence yield, Phi(rel)(5 s) - Phi(rel)(100 ns), i.e., both parameters attain minimum and maximum values after the first/fifth and second/third flash, respectively, and (d) analogous features for the "fast" and "slow" ns-kinetics of the fluorescence rise were observed in suspensions of Chlamydomas reinhardtii cells. A slight phase shift by one flash is ascribed to physiological differences. The applicability of this noninvasive technique to study reactions of photosystem II, especially the reduction kinetics of P680(*)(+) and their dependence on the redox state S(i)() of the WOC, is discussed.

In vitro antimicrobial susceptibility testing of bacterial enteropathogens causing traveler's diarrhea in four geographic regions

The emergence of resistant enteropathogens has been reported worldwide. Few data are available on the contemporary in vitro activities of commonly used antimicrobial agents against enteropathogens causing traveler's diarrhea (TD). The susceptibility patterns of antimicrobial agents currently available or under evaluation against pathogens causing TD in four different areas of the world were evaluated. Pathogens were identified in stool samples from U.S., Canadian, or European adults (18 years of age or older) with TD during 1997, visiting India, Mexico, Jamaica, or Kenya. MICs of 11different antimicrobials were determined against 284 bacterial enteropathogens by the agar dilution method. Ciprofloxacin, levofloxacin, ceftriaxone, and azithromycin were highly active in vitro against the enteropathogens, while traditional antimicrobials such as ampicillin, trimethoprim, and trimethoprim/sulfamethoxazole showed high levels and high frequencies of resistance. Rifaximin, a promising and poorly absorbable drug, had an MIC at which 90% of the strains tested were inhibited of 32 microg/ml, 250 times lower than the concentration of this drug in the stools. Amdinocillin, nalidixic acid, and doxycycline showed moderate activity. Fluoroquinolones are still the drugs of choice for TD in most regions of the world, although our study has a limitation due to the lack of Escherichia coli samples from Kenya and possible bias in selection of the patients for evaluation. Azithromycin and rifaximin should be considered as promising new agents. The widespread in vitro resistance of the traditional antimicrobial agents reported since the 1980s and the new finding of resistance to fluoroquinolones in Southeast Asia are the main reasons for monitoring carefully the antimicrobial susceptibility patterns worldwide and for developing and evaluating new antimicrobial agents for the treatment of TD.

Conservative management of intragastric migration of Swedish adjustable gastric band by endoscopic retrieval

BACKGROUND

Intragastric migration is a known complication of gastric banding for morbid obesity.

METHODS

Instead of immediate reoperation, complete migration of the Swedish Adjustable Gastric Band (SAGB) into the gastric lumen was awaited in 4 patients who were asymptomatic.

RESULTS

After completed migration, the episternally placed access port was removed with the patient under local anesthesia, and the disconnected adjustable band was retrieved endoscopically. All 4 patients underwent rebanding with SAGB within 3 months after extraction.

CONCLUSIONS

With this procedure, patients who are asymptomatic can be spared laparotomy and possibly gastrostomy.

Risk and aetiology of diarrhoea at various tourist destinations

Almost two of three tourists developed traveller's diarrhoea during 2-week stays at high-risk destinations. Large differences in infection rates between hotels were seen. Patients with milder forms of diarrhoea show a similar chronology to those more severely affected. Although enterotoxigenic Escherichia coil was the most frequent cause, viral pathogens were detected more often than in other studies.

Risks of hepatitis B in travelers as compared to immunization status

BACKGROUND

Our objective was to determine the risks of infection with hepatitis B among European travelers and to compare this with the immunization status in various risk groups.

METHODS

A cross-sectional telephone questionnaire survey of randomly selected subjects, in nine European study populations was used. A total of 9, 008 individuals were involved, with approximately 1,000 interviews conducted in each country in the native languages. Situations with a high risk of hepatitis B infection, such as invasive medical procedures, attending to a bleeding person, and skin perforating cosmetic practices, particularly when performed in countries with medium/high transmission risk, and vaccination status of travelers, were the main outcome measures.

RESULTS

Depending upon the destination, 6.6-11.2% of travelers were classified as at high risk of hepatitis B, with 24.4% vaccinated; between 60.8-75.8% of travelers at potential risk, with 19.2% vaccinated; and 33.4% of travelers where no hepatitis B risk was identified. Significantly more travelers who only visited medium/high endemicity regions exposed themselves to a high risk of contracting hepatitis B, (40, 10.5%) compared to travelers who only visited low endemicity regions (225, 6.6%; p <.01).

CONCLUSIONS

A significant proportion of travelers surveyed unwittingly exposed themselves to the risk of hepatitis B infection while at medium/high risk destinations. The majority of at-risk travelers had not been vaccinated, regardless of their destination. Improved advice and clear recommendations to avoid transmission are needed.

Delayed fluorescence emitted from light harvesting complex II and photosystem II of higher plants in the 100 ns-5 micros time domain

This study presents the first report on delayed fluorescence (DF) emitted from spinach thylakoids, D1/D2/Cytb-559 preparations and solubilized light harvesting complex II (LHCII) in the ns time domain after excitation with saturating laser flashes. The use of a new commercially available multichannel plate with rapid gating permitted a sufficient suppression of detector distortions due to the strong prompt fluorescence. The following results were obtained: (a) in dark-adapted thylakoids, the DF amplitudes at 100 ns and 5 micros after each flash of a train of saturating actinic pulses exhibit characteristic period four oscillations of opposite sign: the DF amplitudes at 100 ns oscillate in the same manner as the quantum yield of prompt fluorescence, whereas those at 5 micros resemble the oscillation of the micros kinetics of P680(.) reduction in samples with an intact water oxidizing complex, (b) the quantum yield of total DF emission in the range up to a few micros is estimated to be <10(-4) for thylakoids, (c) the DF of D1/D2/Cytb-559 exhibits a monophasic decay with tau approximately 50 ns, (d) DF emission is also observed in isolated LHCII with biphasic decay kinetics characterized by tau values of 65 ns and about 800 ns, (e) in contrast to thylakoids, the amplitudes of DF in D1/D2/Cytb-559 preparations and solubilized LHCII do not exhibit any oscillation pattern and (f) all spectra of DF from the different sample types are characteristic for emission from the lowest excited singlet state of chlorophyll a. The implications of these findings and problems to be addressed in future research are briefly discussed.