Relative binding affinities of chlorophylls in peridinin-chlorophyll-protein reconstituted with heterochlorophyllous mixtures

Peridinin-chlorophyll-protein (PCP), containing differently absorbing chlorophyll derivatives, are good models with which to study energy transfer among monomeric chlorophylls (Chls) by both bulk and single-molecule spectroscopy. They can be obtained by reconstituting the N-terminal domain of the protein (N-PCP) with peridinin and chlorophyll mixtures. Upon dimerization of these "half-mers", homo- and heterochlorophyllous complexes are generated, that correspond structurally to monomeric protomers of native PCP from Amphidinium carterae. Heterochlorophyllous complexes contain two different Chls in the two halves of the complete structure. Here, we report reconstitution of N-PCP with binary mixtures of Chl a, Chl b, and [3-acetyl]-Chl a. The ratios of the pigments were varied in the reconstitution mixture, and relative binding constants were determined from quantification of these pigments in the reconstituted PCPs. We find higher affinities for both Chl b and [3-acetyl]-Chl a than for the native pigment, Chl a.

Monitoring fluorescence of individual chromophores in peridinin-chlorophyll-protein complex using single molecule spectroscopy

Single molecule spectroscopy experiments are reported for native peridinin-chlorophyll a-protein (PCP) complexes, and three reconstituted light-harvesting systems, where an N-terminal construct of native PCP from Amphidinium carterae has been reconstituted with chlorophyll (Chl) mixtures: with Chl a, with Chl b and with both Chl a and Chl b. Using laser excitation into peridinin (Per) absorption band we take advantage of sub-picosecond energy transfer from Per to Chl that is order of magnitude faster than the Förster energy transfer between the Chl molecules to independently populate each Chl in the complex. The results indicate that reconstituted PCP complexes contain only two Chl molecules, so that they are spectroscopically equivalent to monomers of native-trimeric-PCP and do not aggregate further. Through removal of ensemble averaging we are able to observe for single reconstituted PCP complexes two clear steps in fluorescence intensity timetraces attributed to subsequent bleaching of the two Chl molecules. Importantly, the bleaching of the first Chl affects neither the energy nor the intensity of the emission of the second one. Since in strongly interacting systems Chl is a very efficient quencher of the fluorescence, this behavior implies that the two fluorescing Chls within a PCP monomer interact very weakly with each other which makes it possible to independently monitor the fluorescence of each individual chromophore in the complex. We apply this property, which distinguishes PCP from other light-harvesting systems, to measure the distribution of the energy splitting between two chemically identical Chl a molecules contained in the PCP monomer that reaches 280 cm(-1). In agreement with this interpretation, stepwise bleaching of fluorescence is also observed for native PCP complexes, which contain six Chls. Most PCP complexes reconstituted with both Chl a and Chl b show two emission lines, whose wavelengths correspond to the fluorescence of Chl a and Chl b. This is a clear proof that these two different chromophores are present in a single PCP monomer. Single molecule fluorescence studies of PCP complexes, both native and artificially reconstituted with chlorophyll mixtures, provide new and detailed information necessary to fully understand the energy transfer in this unique light-harvesting system.

Peridinin-chlorophyll-protein reconstituted with chlorophyll mixtures: Preparation, bulk and single molecule spectroscopy

Reconstitution of the 16 kDa N-terminal domain of the peridinin-chlorophyll-protein, N-PCP, with mixtures of chlorophyll a (Chl a) and Chl b, resulted in 32 kDa complexes containing two pigment clusters, each bound to one N-PCP. Besides homo-chlorophyllous complexes, hetero-chlorophyllous ones were obtained that contain Chl a in one pigment cluster, and Chl b in the other. Binding of Chl b is stronger than that of the native pigment, Chl a. Energy transfer from Chl b to Chl a is efficient, but there are only weak interactions between the two pigments. Individual homo- and hetero-chlorophyllous complexes were investigated by single molecule spectroscopy using excitation into the peridinin absorption band and scanning of the Chl fluorescence, the latter show frequently well resolved emissions of the two pigments.

[Management of occult malformations at the lateral skull base]

BACKGROUND

Occult malformations of the lateral skull base are rare anomalies, but can cause severe complications such as recurrent meningitis. Therefore, they need to be precisely delineated and sufficient surgical closure is mandatory.

PATIENTS AND METHODS

Between 1986 and 2004 twenty patients (10 children and 10 adults) with occult malformations at the lateral skull base were treated surgically at the ENT-Department of the Hospital Fulda gAG. Of these 3 Mondini-malformations, 11 defects of the tegmen tympani or the mastoidal roof, 2 dural lesions to the posterior fossa and 4 malformations within the pyramidal apex have been found. Four patients have had multiple anomalies. Routing symptom was in all cases at least one previous meningitis. Radiological diagnostics included high-resolution computed tomography (CT) and magnetic resonance imaging (MRI) as well as CT- or MR-cisternography. Depending on type and localisation of the defect the following surgical algorithm was carried out: The trans-mastoidal approach was used in all cases of Mondini-malformation (including obliteration of the ear), in case of lesions to the posterior fossa as well as partly in anomalies at the tegmen tympani and mastoidal roof, respectively. Defects of the pyramidal apex should be explored via the trans-mastoidal way if the lesion is located caudally to the inner auditory canal (IAC), whereas the trans-temporal approach should be used if the lesion is situated ventral to the IAC and dorso-medially to the internal carotid artery (ICA). The trans-temporal approach was also performed in large defects of the tegmen tympani and mastoidal roof as well as in recurrences.

CONCLUSIONS

In all cases of recurrent meningitis caused by agents of the upper airway tract the basic principle should be to search for occult skull base malformations radiologically as well as by sodium fluorescein endoscopy as long as the anomaly is detected.

Karotisangiographie bei zentro-lateralen Schädelbasisfrakturen?

BACKGROUND

In latero-basal, central or spheno-fronto-orbital skull base fractures the internal carotid artery is more frequently involved in severe lesions than expected.

PATIENTS AND METHODS

Between 1996 and 2003 we examined 684 patients with Glasgow Coma Scales (GCS) between 2 and 15, median 7.2, using computed tomography (CT). In suspicion of a latero-basal, central or spheno-fronto-orbital fractur they got an additional high resolution skull base CT. If the bony canal of the internal carotid artery (ICA) was involved the patient underwent digital subtraction angiography (DSA). The ICA lesion was treated either interventional neuroradiologically, by surgery or only conservatively.

RESULTS

Of the 684 patients 33 (4.8 %) had fractures of the ICA bony canal and therefore underwent DSA. Among them were 25 men and 8 women (mean age 35.3 years). Lesions of the ICA were seen in 1.9 % of the patients. A traumatic cavernous-carotid fistula was found in 7 patients (1 %) and in 6 patients (0.9 %) a dissection and/or an aneurysm of the ICA was diagnosed. Six of the patients had clinical symptoms. The lesions were treated primarily interventional neuroradiologically (n = 5) as well as surgically in two cases by clipping the aneurysm and closing the sphenoid sinus, respectively.

CONCLUSIONS

Vessel lesions of the ICA in skull base fractures and involvement of the bony carotid canal are more frequent than mentioned in current literature. A solid diagnosis can only be achieved by DSA. Early diagnosis and treatment is important for improving the prognosis of these often multiply injured patients.

Funktionelle Ergebnisse, Lebensqualität, kognitive und affektive Konsequenzen nach transtemporaler Exstirpation von Akustikusneurinomen

BACKGROUND

The aim of the study was to evaluate postoperative hearing, facial nerve function, quality of life (QOL), affective status and neuropsychological performance after trans-temporal removal of acoustic neuromas (AN).

PATIENTS AND METHODS

A retrospective analysis was carried out in 89 patients with AN who were operated at the ENT-Department of the Hospital Fulda between 1988 and 2004. Median follow up was 57 months. Of these 41 patients were additionally examined by a psychologist for evaluation of QOL, neuropsychological functions and affective disorders using several questionnaires.

RESULTS

The AN were classified as follows: Type A = 53 %, type B = 35 % and type C = 12 %. One year postoperatively facial nerve function was excellent in 93.3 % of the patients (grade I and II). In 53 % of cases hearing could be preserved. The subjective QOL was expressed through depression and social withdrawal associated with deafness. However, facial nerve dysfunction did not lead to QOL effect. Objective QOL (functional level) was reduced because of verbal memory disturbances and symptoms like dizziness. In 47.5 % of the patients affective and/or neuropsychological dysfunctions were diagnosed. Subsequent MRI evaluation showed lesions of the temporal lobe in 40.5 % of the cases. Of these 80 % suffered from cognitive and/or affective disturbances.

CONCLUSIONS

The cognitive and affective disturbances after trans-temporal removal of AN could be to a certain degree due to the elevation of the temporal lobe during surgery. Further research, especially pre- and postoperative examination of QOL and psychological state as well as the comparison between different approaches, particularly trans-temporal vs suboccipital have to clear up specific morbidity of the different approaches.

[The duration of expulsion and the separation of the afterbirth in breeding cows--a contribution to the improvement of parturition monitoring]

The objective of this study was to obtain data on the duration of the expulsion and afterbirth stages and on the rate of contractions of the abdominal muscles in dams with eutocia (n = 81; heifers: 11; cows: 70). We also looked into the questions of whether and at which stage of expulsion there were differences in these parameters between cows and heifers as well as purebred Simmental (n = 49) and Simmental X Limousin (n = 21). The total period of expulsion (period from appearance of the phalanxes in the rima vulvae until the complete expulsion of the calf) was 19.7 +/- 2.1 minutes. It took 17.3 +/- 2.3 minutes for the head to emerge. Further expulsion required 1.9 +/- 1.7 minutes. At an average of 40.1 +/- 1.5 minutes, the expulsion stage was longer in heifers than in cows, in which it lasted 18 +/- 2.1 minutes (p < 0.01). The differences are due to the time that the head took to emerge. While this stage of labor lasted 15.3 +/- 2.3 minutes in cows, this interval was clearly longer in heifers, lasting 38.1 +/- 1.5 minutes (p < 0.01). No statistically significant difference was observed in the course of further expulsion and there were not any differences detected between purebred Simmental and Simmental X Limousin. An average of 67.5 +/- 1.6 abdominal contractions were required for complete expulsion, 56.5 +/- 1.7 contractions of the abdominal muscles were necessary until the head appeared. After 9.3 +/- 1.6 abdominal presses, the calf had completely emerged. There was a statistically significant difference between cows (52.8 +/- 1.7) and heifers (93.3 +/- 1.6) until the expulsion of the head (p < 0.01). No breed-specific differences were observed. Separation of the afterbirth was observed in 95.0% of the animals up to the eighth hour post partum. Retarded separation and retained placenta were recorded in 2.5% of the animals in each case. 82.7% of the animals performed placentophagy. No placentophagy was observed when the placenta was retarded. No differences were detected between heifers and cows and the breeds with regard to the separation of the afterbirth and the incidence of placentophagy.

Therapeutisches Management von Gehörgangs- und Mittelohrkarzinomen

BACKGROUND

Carcinomas of the external auditory canal (EAC) and the middle ear are rare and considered to have a poor prognosis. The recommended therapeutic strategy consists of surgical excision and postoperative radiotherapy. However, there are different opinions about the extend of the primary operation.

PATIENTS AND METHODS

A series of 21 patients with carcinoma of the EAC and middle ear were treated at the ENT-Department of the Hospital Fulda from 1985 to 2003. Their records and radiologic findings were reviewed retrospectively with particular reference to tumor type and size, its relation to surrounding tissues, surgical procedures and radiation techniques. The tumors were staged according to the modified Pittburgh staging system for temporal bone carcinomas. The average follow-up time was 6.2 years (range 0.2 - 18.75).

RESULTS

17 patients suffered from carcinoma of the EAC, 4 carcinomas were primarily located in the middle ear. There were 15 squamous cell carcinomas, 3 adenoidcystic carcinomas, 2 adenocarcinomas and one mucoepidermoid carcinoma. 12 patients came primarily to our institution and were staged as follows: pT1 (n = 2), pT3 (n = 2), pT4 (n = 8). 8 patients showed up with recurrent or residual tumors (all of T3 or T4 stage). One patient could not be classified. In 5 cases the tumor was inoperable. These patients underwent combined chemoradiation therapy. All other 16 patients were operated and most of them received adjuvant radiation therapy. In the group of patients who were primarily operated overall 5-year survival rate was 100 %. In contrast, patients who's recurrent or residual tumors were resected had a 5-year survival rate of only 33 %. Patients who received combined chemoradiation therapy showed a 2-year survival rate of 75 %.

CONCLUSION

Carcinoma of the EAC and middle ear should be treated primarily by a lateral or subtotal temporal bone resection stage dependent combined with a parotidectomy as well as a neck dissection. Local resection of the EAC is not sufficient, not even in T1 tumors. As from stage T2, in cases of recurrent tumor removal and questionable free margins as well as in cases with lymph node metastases an adjuvant radiation therapy should be added. The most important survival factor is removal of the primary tumor with histologically clear margins.