Effective diffusivities and mass fluxes in fungal biopellets

Mass transport within biological aggregates is a key process that can determine overall turnover rates in submerged cultivations. A parameter commonly used for its description is the effective diffusion coefficient D(eff), which is highly dependent on biomass density and structure. Different approaches have been used to estimate or measure D(eff), yet the data still shows broad scattering. This study provides experimental data on effective diffusivities of oxygen within fungal pellets. A correlation is found with the hyphal gradient (dh/dr), which is a morphological parameter describing the structure of the pellet periphery. Furthermore, the dependency of D(eff) on fluid dynamic conditions at the pellet is investigated. The comparison of the results with data from literature clearly demonstrates the influence of the experimental methodology applied for determination of D(eff). Moreover, it is shown that while diffusion limitation of whole pellets is mainly a function of size, the influence of advection in the outer zone of pellets that is supplied with oxygen is actually rather high. Thus, it is concluded that the effective diffusion coefficient might not be sufficient for the description of mass transport within the pellet periphery for a broad range of realistic fluid dynamic conditions during cultivation. Nevertheless, although actual mass transport rates inside pellets are unknown, mass fluxes can be calculated on the basis of spatially resolved data of oxygen and biomass distribution within the pellet.

Optically controlled interparticle distance tuning and welding of single gold nanoparticle pairs by photochemical metal deposition

We report on the in-situ controlled tuning of the particle gap in single pairs of gold nanodisks by photochemical metal deposition. The optically induced growth of nanodisk dimers fabricated by electron beam lithography leads to a decrease of the interparticle gap width down to 0 nm. Due to the increasing particle size and stronger plasmonic coupling, a smooth redshift of the localized surface plasmon (LSP) resonances is observed in such particle pairs during the growth process. The interparticle gap width, and hence the LSP resonance, can be tuned to any desired spectral position. The experimental results we obtain with this nanoscale fabrication technique are well described by the so-called plasmon ruler equation. Consequently, both the changes in particle diameter as well as in gap width can be characterized in-situ via far-field read-out of the optical properties of the dimers.

Histomorphological tumor regression grading of esophageal carcinoma after neoadjuvant radiochemotherapy: which score to use?

Histopathological tumor regression grade (TRG) has been shown to be a prognostic factor in patients with esophageal cancer after neoadjuvant radiochemotherapy (RCT). The system introduced by Mandard to group TRG (Cancer 1994;73:2680-2686) has been used to analyse and discuss its prognostic significance on survival in a single institution retrospective analysis: TRG 1 (complete regression) - TRG 5 (absence of regressive changes). Sixty patients with locally advanced (T3/4 or N1) adenocarcinoma or squamous cell carcinoma received cisplatin-based RCT. Three to four weeks later operation for curative intent was performed. Median follow-up was 17.7 months. Histopathological tumor stages were stage 0 in 17%, stage I in 10%, stage II in 60%, stage III in 12% and stage IVA in 1%. The 5-year overall survival (OS) rate was 35%. In univariate analysis, ypN-status and TRG correlated significantly with OS (P = 0.004, P = 0.0008, respectively). While OS of TRG 1 differed significantly from all other groups, no differences in OS between the other TRG groups were seen. Patients with complete tumor regression after neoadjuvant RCT showed a much better survival than patients with tumors that responded less to induction therapy. Further qualitative subdivision of tumor regression could not identify patient groups with significant differences in prognosis. After comparing our data with the literature, it is reasonable to consider classifying all patients into 'Complete tumor regression' and 'Incomplete tumor regression'.

A comparison of three-field and four-field techniques in different clinical target volumes in prostate cancer irradiation using dose volume histograms: a prospective three-dimensional analysis

The purpose of the current study was to quantitatively assess differences between irradiation techniques on normal tissue exposure in different clinical target volumes (CTVs) in irradiation of prostate cancer. 14 patients with prostate cancer undergoing external beam radiotherapy were investigated. The prostate and prostate + proximal/entire seminal vesicles were delineated as CTVs. A three-field and two different four-field plans were generated and compared concerning rectum, bladder and femoral head dose-volume histograms (DVHs). The exposure of the rectum exposed to 40-60 Gy was significantly lower for all CTVs with the three-field technique compared with both four-field techniques. The exposure of the rectum to 70 Gy was significantly lower for all CTVs with the weighted four-field technique compared with the unweighted four-field and three-field techniques. The weighted four-field technique was worst in bladder dose sparing for the three CTVs. Comparing the three-field and the unweighted four-field technique for irradiation of the prostate and prostate + entire seminal vesicles, no technique provided a clear advantage or disadvantage in bladder dose sparing. For irradiation of the prostate + proximal seminal vesicles the unweighted four-field technique provided the best bladder dose sparing. Concerning the exposure of the femoral heads, the three-field technique was significantly worse for the three CTVs compared with both four-field techniques. No difference was found between the unweighted and the weighted four-field techniques. In conclusion, none of the studied techniques consistently proved superior in different CTVs in prostate cancer irradiation with respect to sparing all organs at risk. The absolute differences between the three techniques were small and the clinical relevance of these findings is uncertain.

Medium term results in keratoprostheses with biocompatible and biological haptic

PURPOSE

Corneal grafts or limbal stem cell transplantation are often unsuccessful in patients with severe ocular surface disorders such as severe dry eye syndrome, symblepharon or diffuse vascularisation. In those patients, a keratoprosthesis (KPro) may be an alternative for the recovery of vision. Various KPro differ from each other in the material of the haptic that supports the optic cylinder. The haptic may be made of biocompatible or biological material such as tibia bone (TKPro) or dentine and alveolar bone (osteo-odonto-keratoprosthesis, OOKP). On the basis of our experience, we wanted to comment on the value of different KPro.

METHODS

Over the last 10 years we have implanted a total of 35 KPro, 29 with biological haptic (25 OOKP and four TKPro), and six KPro with biocompatible haptic (one Legais KPro, five Pintucci KPro). A follow up examination was carried out approximately every6 months.

RESULTS

The patients gained a visual acuity of > or =0.9 in 20.6%, of > or =0.5 in 52.9%, of > or =0.2 in 61.8% and a significant improvement in visual acuity in 76.5%, respectively. There was no significant difference between the various types of KPro concerning the best postoperative visual acuity. All patients showing poor improvement had a pre-existing end stage secondary glaucoma or other retinal damage. The median follow-up was 2.9 years (maximum 8) for OOKP, 1 year for TKPro, 1 year (maximum 2) for Pintucci Kpro and 6 month for Legeais KPro. During this period, only one of the KPro with biological haptic was lost (one TKPro after 1 year), compared with four out of six of the KPro with biocompatible haptic (P<0.0001).

CONCLUSIONS

Fixation of the KPro by a root of the patient s own tooth (OOKP) leads to the best results in the long-term follow up, as our results as well as the literature demonstrate. As long as a KPro is in place, the visual acuity is as good as the retinal function. For the ranking of different types of KPro, the percentage and the duration of the anatomic success are most important. The comparability of the various KPro results may be limited, since the patients were not randomised and the four groups differ in number.

[Development of cell content and shedding of Prototheca spp. in milk from infected udder quarters of cows]

It was the objective of this study to analyse shedding patterns and somatic cell counts in cows and quarters infected with Prototheca spp. and to evaluate two approaches to identify infected animals by somatic cell count (SCC) or by bacteriological analysis of pooled milk samples. Five lactating dairy cows, chronically infected with Prototheca spp. in at least one quarter were studied over 11 weeks to 13 months. Quarter milk samples and a pooled milk sample from 4 quarters were collected aseptically from all quarters of the cows on a weekly basis. Culture results of quarter milk and pooled samples were compared using cross tabulation. SCC of quarter milk samples and of pooled samples were related to the probability of detection in the infected quarters and cows, respectively. Shedding of Prototheca spp. was continuous in 2 of 8 quarters. In the other quarters negative samples were obtained sporadically or over a longer period (1 quarter). Overall, Prototheca spp. were isolated from 83.6% of quarter milk samples and 77.0% of pooled milk samples of infected quarters and cows. Somatic cell counts were higher in those samples from infected quarters that contained the algae than in negative samples (p < 0.0001). The same applied for composite samples from infected cows. Positive samples had higher SCC than negative samples. However, Prototheca spp. were also isolated from quarter milk and pooled samples with physiological SCC (i.e. < 10(5)/ml). Infected quarters that were dried off did not develop acute mastitis. However, drying off had no effect on the infection, i.e. samples collected at calving or 8 weeks after dry off still contained Prototheca spp. Results indicate that pre-selection of cows to be sampled for Prototheca spp. by SCC and the use of composite samples are probably inadequate in attempts to eradicate the disease. However, due to intermittent shedding of the algae in some cows, single herd sampling using quarter milk samples probably also fails to detect all infected cases. Therefore, continuous monitoring of problem cows with clinical mastitis or increased SCC in herds during eradication programs is recommended.

Oxygen profiles and biomass distribution in biopellets ofAspergillus niger

Morphology of fungal pellets has a significant influence on mass transfer and turnover processes in submerged cultures. There are many reports in literature that biomass is not distributed homogeneously over the pellet radius, yet quantitative data is rare. This study presents a method for the quantification of fungal pellet structure (Aspergillus niger). Confocal laser scanning microscopy (CLSM) is used in combination with image analysis freeware (Image J). Hyphal distribution is resolved spatially in radial direction. Quantitative morphological parameters are derived from digital images especially from the peripheral regions of the pellet that are not oxygen limited. This morphological information is combined with data of microelectrode measurements in the same pellets. Results show that the morphological parameters obtained can describe the impact of pellet structure on oxygen gradients much better than average biomass density. It is concluded that CLSM and image analysis are powerful tools not only to generate valuable data for quantitative description of pellet morphology. In addition, this data may be used in mathematical models to improve predictions of mass transfer and substrate conversion in mycelial aggregates.

Concurrent low-dose cisplatin and thoracic radiotherapy in patients with inoperable stage III non-small cell lung cancer: a phase II trial with special reference to the hemoglobin level as prognostic parameter

PURPOSE

To evaluate the efficacy of concurrent radiochemotherapy in patients with stage III non-small cell lung cancer (NSCLC), and to examine the effect of hemoglobin levels on survival of those patients. The negative impact of anemia on survival has been noticed for other cancer sites including the head and neck, and the uterine cervix, but it has been rarely described in NSCLC cancer patients treated with radiotherapy.

METHODS

From April 1995 through March 2002, 56 patients with inoperable stage III non-small lung cancer were treated with radiotherapy consisting of 60 Gy (50 Gy+10 Gy boost) given in 30 fractions of 2 Gy daily, 5 days a week, over a period of 6 weeks, and concurrent low-dose daily chemotherapy (CHT) consisting of 6 mg/m(2) of cisplatin given Mondays-Fridays during weeks 1-2 and 5-6. All patients had stage III disease and ages ranged from 39 to 81 years old (median 63.9 years).

RESULTS

The 2-year and 3-year survival rates were 34% and 16%, respectively. Patients with a pretreatment hemoglobin level superior or equal to 11.6 g/dl had a 2-year survival rate of 52% as compared to 15.5% for patients with a pretreatment hemoglobin level inferior to 11.6 g/dl (p=0.0075). Patients with higher KI (>70%) showed better survival rates than those with lower KI. Surprisingly, patients in stage IIIA did not survive significantly longer than those in stage IIIB. Hematological toxicity (grade > or =2) prevailed (25%), followed by esophageal (5.4%) and bronchopulmonary (2%) toxicity. Only three patients experienced acute grade 3 hematological toxicity. Because of acute toxic effects, irradiation was interrupted in 8 patients (14.3%) for 7-13 days (median 7.5 days). Late high-grade (> or =3) toxicity was not found. No grade 4 toxicity or treatment-related deaths were observed during this study.

CONCLUSION

Our data show that concurrent radiotherapy with daily low dose cisplatin is well tolerated, and shows survival rates comparable to more aggressive treatment regimens. A combination of this chemotherapy with accelerated hyperfractionated radiotherapy might improve the results in the future. Furthermore, we could show that the hemoglobin levels prior to therapy have an influence on the prognosis, where lower levels were associated with worse outcome. Further trials should consider supplementation with erythropoietin.

Binding H2, N2, H−, and BH3 to Transition-Metal Sulfur Sites: Synthesis and Properties of[Ru(L)(PR3)(‘N2Me2S2’)] Complexes (L=η2-H2, H−, BH3; R=Cy,iPr)

The reactions of [Ru(N(2))(PR(3))('N(2)Me(2)S(2)')] ['N(2)Me(2)S(2)'=1,2-ethanediamine-N,N'-dimethyl-N,N'-bis(2-benzenethiolate)(2-)] [1 a (R=iPr), 1 b (R=Cy)] and [micro-N(2)[Ru(N(2))(PiPr(3))('N(2)Me(2)S(2)')](2)] (1 c) with H(2), NaBH(4), and NBu(4)BH(4), intended to reduce the N(2) ligands, led to substitution of N(2) and formation of the new complexes [Ru(H(2))(PR(3))('N(2)Me(2)S(2)')] [2 a (R=iPr), 2 b (R=Cy)], [Ru(BH(3))(PR(3))('N(2)Me(2)S(2)')] [3 a (R=iPr), 3 b (R=Cy)], and [Ru(H)(PR(3))('N(2)Me(2)S(2)')](-) [4 a (R=iPr), 4 b (R=Cy)]. The BH(3) and hydride complexes 3 a, 3 b, 4 a, and 4 b were obtained subsequently by rational synthesis from 1 a or 1 b and BH(3).THF or LiBEt(3)H. The primary step in all reactions probably is the dissociation of N(2) from the N(2) complexes to give coordinatively unsaturated [Ru(PR(3))('N(2)Me(2)S(2)')] fragments that add H(2), BH(4) (-), BH(3), or H(-). All complexes were completely characterized by elemental analysis and common spectroscopic methods. The molecular structures of [Ru(H(2))(PR(3))('N(2)Me(2)S(2)')] [2 a (R=iPr), 2 b (R=Cy)], [Ru(BH(3))(PiPr(3))('N(2)Me(2)S(2)')] (3 a), [Li(THF)(2)][Ru(H)(PiPr(3))('N(2)Me(2)S(2)')] ([Li(THF)(2)]-4 a), and NBu(4)[Ru(H)(PCy(3))('N(2)Me(2)S(2)')] (NBu(4)-4 b) were determined by X-ray crystal structure analysis. Measurements of the NMR relaxation time T(1) corroborated the eta(2) bonding mode of the H(2) ligands in 2 a (T(1)=35 ms) and 2 b (T(1)=21 ms). The H,D coupling constants of the analogous HD complexes HD-2 a ((1)J(H,D)=26.0 Hz) and HD-2 b ((1)J(H,D)=25.9 Hz) enabled calculation of the H--D distances, which agreed with the values found by X-ray crystal structure analysis (2 a: 92 pm (X-ray) versus 98 pm (calculated), 2 b: 99 versus 98 pm). The BH(3) entities in 3 a and 3 b bind to one thiolate donor of the [Ru(PR(3))('N(2)Me(2)S(2)')] fragment and through a B-H-Ru bond to the Ru center. The hydride complex anions 4 a and 4 b are extremely Brønsted basic and are instantaneously protonated to give the eta(2)-H(2) complexes 2 a and 2 b.

[The Ahmed glaucoma valve. Medium term results]

BACKGROUND

In complicated glaucoma, when classical filtrating surgery would be ineffective, aqueous shunts may be used. Complications due to hypotonia are reduced by valved systems, such as the Ahmed glaucoma valve (AGV).

METHOD

In a retrospective case control study, 28 patients with complicated glaucoma were included. In addition to the clinical examination, we examined the size and function of the filtering area using ultrasound.

RESULTS

The medium term follow-up was 25+/-16 months, the preoperative intraocular pressure (IOP) 35.5 mmHg+/-10.3 while 17 eyes were pseudophakic and nine aphakic. In the first weeks after AGV implantation, the mean IOP was 6.3+/-2.5 mmHg. In nine eyes, the pressure was less than 5 mmHg and five developed a temporary choroidal detachment. At the last visit, IOP was regulated in 22 eyes (82.1%). There was no correlation between IOP regulation and the size of the filtering bleb or the increase in the latter by digital pressure.

CONCLUSION

In the management of complicated glaucoma, if there is a high risk of failure due to conjunctival scarring, AGV implantation can be used as a save procedure with a success rate comparable to other glaucoma implants.

Binding N2, N2H2, N2H4, and NH3 to transition-metal sulfur sites: modeling potential intermediates of biological N2 fixation

In the quest for low-molecular-weight metal sulfur complexes that bind nitrogenase-relevant small molecules and can serve as model complexes for nitrogenase, compounds with the [Ru(PiPr(3))('N(2)Me(2)S(2)')] fragment were found ('N(2)Me(2)S(2)'(2-)=1,2-ethanediamine-N,N'-dimethyl-N,N'-bis(2-benzenethiolate)(2-)). This fragment enabled the synthesis of a first series of chiral metal sulfur complexes, [Ru(L)(PiPr(3))('N(2)Me(2)S(2)')] with L=N(2), N(2)H(2), N(2)H(4), and NH(3), that meet the biological constraint of forming under mild conditions. The reaction of [Ru(NCCH(3))(PiPr(3))('N(2)Me(2)S(2)')] (1) with NH(3) gave the ammonia complex [Ru(NH(3))(PiPr(3))('N(2)Me(2)S(2)')] (4), which readily exchanged NH(3) for N(2) to yield the mononuclear dinitrogen complex [Ru(N(2))(PiPr(3))('N(2)Me(2)S(2)')] (2) in almost quantitative yield. Complex 2, obtained by this new efficient synthesis, was the starting material for the synthesis of dinuclear (R,R)- and (S,S)-[micro-N(2)[Ru(PiPr(3))('N(2)Me(2)S(2)')](2)] ((R,R)-/(S,S)-3). (Both 2 and 3 have been reported previously.) The as-yet inexplicable behavior of complex 3 to form also the R,S isomer in solution has been revealed by DFT calculations and (2)D NMR spectroscopy studies. The reaction of 1 or 2 with anhydrous hydrazine yielded the hydrazine complex [Ru(N(2)H(4))(PiPr(3))('N(2)Me(2)S(2)')] (6), which is a highly reactive intermediate. Disproportionation of 6 resulted in the formation of mononuclear diazene complexes, the ammonia complex 4, and finally the dinuclear diazene complex [micro-N(2)H(2)[Ru(PiPr(3))('N(2)Me(2)S(2)')](2)] (5). Dinuclear complex 5 could also be obtained directly in an independent synthesis from 1 and N(2)H(2), which was generated in situ by acidolysis of K(2)N(2)(CO(2))(2). Treatment of 6 with CH(2)Cl(2), however, formed a chloromethylated diazene species [[Ru(PiPr(3))('N(2)Me(2)S(2)')]-micro-N(2)H(2)[Ru(Cl)('N(2)Me(2)S(2)CH(2)Cl')]] (9) ('N(2)Me(2)S(2)CH(2)Cl'(2-) =1,2-ethanediamine-N,N'-dimethyl-N-(2-benzenethiolate)(1-)-N'-(2-benzenechloromethylthioether)(1-)]. The molecular structures of 4, 5, and 9 were determined by X-ray crystal structure analysis, and the labile N(2)H(4) complex 6 was characterized by NMR spectroscopy.

Drainage devices in glaucoma surgery

Glaucoma drainage devices, also termed aqueous shunts (AS), are widely used in the USA. Indications for AS include excessive conjunctival scarring diminishing the success of another filtration surgeries, abnormalities of the iridocorneal angle, neovascular glaucoma, presence of corneal grafts, and inflammatory glaucoma. Qualified success has been achieved for many years in 50 to 100 % of the treated eyes, depending on the patient selection. An AS consists of a silicone tube that is inserted into the anterior chamber and a plate (explant) made of silicone or polypropylene. The latter is positioned between the recti muscles. Within some weeks the surrounding tissue forms a fibrous bleb around the plate. This serves as a permanent filtration reservoir. The most serious complication is postoperative hypotonia, that can lead to serious choroidal detachment, suprachoroidal hemorrhage, anterior chamber flattening, and corneal decompensation. To avoid this complication some devices, e.g. the Ahmed Glaucoma valve and the Krupin valve, have integrated mechanisms to sustain a residual intraocular pressure. With other devices such as the Molteno and the Baerveldt devices the tube has to be temporarily ligated until a scar area forms around the explant. On the other hand, fibrous infiltration of the wall of the bleb often leads to a reversible rise in intraocular pressure about one to four months after surgery which can be treated by massaging the bulb, needling the bleb, or injection of antimetabolites. There are no obvious differences between the different AS regarding the success of pressure control. With appreciation of indications and therapy of complications, AS are an useful option in the management of complicated glaucoma, where conventional filtration surgery is considered to carry a high risk of failure.

An RAPD (random amplified polymorphic DNA) analysis of genetic population structure of Balea biplicata (Gastropoda: Clausiliidae) in fragmented floodplain forests of the Elster/Saale riparian system

Eight German populations of the land snail Balea biplicata (Mollusca: Clausiliidae) were studied using the randomly amplified polymorphic DNA-polymerase chain reaction and morphometrics (principal component and discriminant analysis) to examine population structure and gene flow patterns in a fragmented landscape mosaic along the Elster/Saale riparian system, Germany. A variety of population genetic analyses targeting either more on the geographic scale of gene flow (genetic distances, F statistics, Mantel test) or on local genotypic structure (heterozygosity, linkage disequilibrium, bottleneck probability) showed that (1) the population system in total is governed by high gene flow independent of geographic distance, (2) genetic structure on the narrower sampling scale is mainly determined by stochastic processes due to genetic drift in small isolated and frequently recolonized populations, and (3) the morphometrical variation of the populations was related neither to habitat nor to genetic heterogeneity. The potentials for active and passive dispersal capacity of the snails and possible environmental impacts on their population structure are discussed.

Effect of keratinocyte growth factor on the proliferation, clonogenic capacity and colony size of human epithelial tumour cells in vitro

PURPOSE

The effect of recombinant human keratinocyte growth factor (rHuKGF) on the proliferation, clonogenic capacity and colony size of low-passage human epithelial tumour cells was tested in vitro.

MATERIALS AND METHODS

Five tumour cell cultures derived from head and neck squamous cell carcinomas, three cultures derived from pleural effusions of carcinomas of different origin and normal human nasal epithelial cells were analysed in passages 2-4. Expression of FGF7 and its receptor (FGFR2) were determined by the RNase protection assay. Cells were incubated with rHuKGF (10-200 ng ml(-1)) 3 days before or immediately after plating for clonal growth in serum-depleted media. To determine cellular radiosensitivity, single doses of 1-8 Gy X-rays were applied. Colony formation as well as colony size, reflecting the number of cell divisions, was determined after 10-15 days of growth in rHuKGF-treated and control cells.

RESULTS

Normal nasal epithelial cells showed a two- to threefold increase in the number of cell divisions due to rHuKGF-treatment. In tumour cell cultures, significant stimulation of proliferation occurred in only one of eight samples. Tumour cells expressed FGF7 mRNA and protein, and low levels of FGFR2 mRNA. The addition of rHuKGF to the medium of the tumour cell cultures influenced neither radiation-induced impairment of proliferation nor clonogenic cell survival.

CONCLUSION

rHuKGF has been shown to ameliorate the radiation tolerance of normal epithelia. The minimum in vitro tumour cell response to rHuKGF compared with normal epithelial cells suggests a potential for selective protection of normal epithelia during radiotherapy. The low FGFR2 expression as well as the FGF7 expression in the tumour cells may contribute to their resistance to rHuKGF treatment.

[Drainage systems in glaucoma surgery]

Glaucoma drainage devices, also known as aqueous shunts (AS) are widely used in the USA. They consist of a silicone tube that is inserted into the anterior chamber and connected to a plate made of silicone or polypropylene, the explant. The latter is positioned between the recti muscles and over several weeks the surrounding tissue forms a fibrous bleb around the plate. This serves as a permanent filtration reservoir.Recurrent failure of filtrating surgery is the main indication for the use of AS. Other indications include situations in which the formation of a filtering bleb seems to be unpromising because of extensive conjunctival scarring. Qualified success has been achieved for many years in 50-100% of the eyes treated depending on patient selection. The most serious complication is postoperative hypotonia that can lead to serious chorioidal detachment, suprachorioidal hemorrhage, flat anterior chamber and corneal decompensation. To avoid this complication some devices, i.e.the Ahmed Glaucoma and the Krupin valve have integrated mechanisms to sustain a residual intraocular pressure. With other devices i.e. the Molteno and the Baerveldt devices, the tube has to be temporarily ligated until bleb formation has started. On the other hand fibrous infiltration of the bleb 1-4 months after the surgery often leads to a reversible rise in introcular pressure, which can be treated by massaging the bulbus, needling the bleb or injection of antimetabolites. There are no obvious differences between the various forms of AS with regard to the success of pressure regulation. In summary,by close scrutiny of indications and management of complications,drainage systems are a useful option in the management of complicated glaucoma that carry a high risk of failure from conventional filtering surgery.

Monitoring of therapy in head and neck patients during the radiotherapy by measurement of Cyfra 21-1

PURPOSE

Cyfra 21-1, measuring serum fragments of cytokeratin 19, has been found to be related to tumour stage and tumour size in patients with cervical cancer. It could be a promising marker in squamous lung cancer. We evaluated this new marker with carcinoembryonic antigen, (CEA) and squamous cell carcinoma antigen (SCC-Ag) in the monitoring of 27 patients with head and neck cancer.

PATIENTS AND METHODS

The retrospective study group consisted of 27 patients, 17 not suited for surgery and 10 after laser resection. Patients were clinically staged according to the TNM-classification. The mean age of the patients was 53 years (range 37-70 years). Serum levels of each marker were studied in relation to tumour stage and clinical status of the patients during radiotherapy and 6 weeks after the end of the treatment. The clinical performance of the various assays to separate those patients with complete remission from those patients with the presence of tumour was assessed.

RESULTS

Pre-treatment serum Cyfra 21-1, CEA, and SCC-Ag levels were not related to stage of disease and were not found to be predictive of tumour response. The clinical performance of post-treatment serum SCC-Ag levels in predicting the presence of tumour was not better than the Cyfra 21-1 assays.

CONCLUSION

We could not conclude from this study that Cyfra 21-1 marker is an additional parameter in identifying patients at risk of residual tumour after treatment, recurrent or progressive disease. An elevation of cyfra 21-1 marker was not detectable in 70% of the cases with macroscopic tumour. Therefore, Cyfra 21-1 is not a reliable parameter for the monitoring of patients with head and neck cancer during radiotherapy.

Heterologous amplification of microsatellite markers from colubroid snakes in European natricines (serpentes: natricinae)

Eighteen microsatellite loci developed for a range of snake species (New World natricines, elapids, crotalids) were tested against European natricines (Natrix natrix, N. maura, and N. tessellata) in cross-species amplification experiments. Five loci were polymorphic (average expected heterozygosity 0.749 for a population of N. natrix in Amsterdam, mean sample size 47.8) and three loci were monomorphic. The remainder could not be consistently scored or failed to amplify. Further tests on single individuals of a diverse set of eight species of colubroid snakes showed that 15 of the 18 loci could be cross-amplified in at least one of these species. We conclude that our results show promise for the utilization of these markers for experimental assessments of genetic variation in the phylogenetically closely related group of European natricine snakes with emphasis on N. natrix. The full suite of microsatellite markers now available for snakes may show additional potential for subsequent investigation across a broader range of colubroid snakes.

Functional cooperation of Epstein-Barr virus nuclear antigen 2 and the survival motor neuron protein in transactivation of the viral LMP1 promoter

Epstein-Barr virus nuclear antigen 2 (EBNA2) is essential for viral transformation of B cells and transactivates cellular and viral target genes by binding RBPJkappa tethered to cognate promoter elements. EBNA2 interacts with the DEAD-box protein DP103 (DDX20/Gemin3), which in turn is complexed to the survival motor neuron (SMN) protein. SMN is implicated in RNA processing, but a role in transcriptional regulation has also been suggested. Here, we show that DP103 and SMN are complexed in B cells and that SMN coactivates the viral LMP promoter in the presence of EBNA2 in reporter gene assays and in vivo. Subcellular localization studies revealed that nuclear gems and/or coiled bodies containing DP103 and SMN are targeted by EBNA2. Protein-protein interaction experiments demonstrated that DP103 binds to SMN exon 6 and that both EBNA2 and SMN interact with the C terminus of DP103. Furthermore, a DP103 binding-deficient SMN mutant was released from nuclear gems and/or coiled bodies and further enhanced coactivation. In addition, impaired transactivation of a DP103 binding-deficient EBNA2 mutant was rescued by overexpression of SMN. Testing different promoter constructs in luciferase assays showed that RBPJkappa is required but not sufficient for coactivation by EBNA2 and SMN. Overall, our data suggest that EBNA2 might target spliceosomal complexes by binding to DP103, thereby releasing SMN which subsequently exerts a coactivational function within the RNA-polymerase II transcription complex on the LMP1 promoter.

[The role of high-energy imaging in a radiotherapy service and its incorporation in a network]

To directly compare the clinical efficacy of electronic to film portal images and the advantages of comparing directly on the monitor the simulation image and the portal image.

MATERIAL AND METHODS

This study was designed to compare clinical efficacy of electronic to film portal images acquired using a liquid matrix ion-chamber electronic portal imaging device (EPID) and a conventional film system. Two radiation oncologists served as observers and evaluated a total of 30 sets of images for three different treatment sites: lung, pelvis, and head/neck. Each set of images included a simulation image, a portal film, a video paper print of electronic portal images, and a video prints of electronic portal images. Four to six anatomical landmarks were selected from each treatment site. Each observer was asked to rate each landmark in terms of its clinical visibility and to rate the ease of making the pertinent verification decision in the corresponding electronic and film portal images with the aid of the simulation image. The time needed to obtain and analyse a conventional portal image and an EPID would be analysed for the radiotherapist and the medical technicians.

RESULTS

Ratings for the visibility of landmarks and for the verification decision of treatment ports were similar for electronic and film images for most landmarks. However, vertebral bodies and several landmarks in the pelvis such as the acetabulum and pubic symphysis were more visible in the electronic portal images than in the portal film images. For the medical technicians, the EPID is more comfortable, and they do not need to develop any images.

CONCLUSION

The visibility of landmarks in electronic portal images is comparable to that in film portal images. Verification of treatment ports based only on electronic portal images acquired using an electronic portal imaging device is generally achievable. Thus the integration of the EPID and simulation image in a network provides more flexibility in the daily work of a medical radiotherapy team.

Geographical patterns of genetic subdivision in the cellar spider Pholcus phalangioides (Araneae)

Geographical patterns of gene flow and drift were analysed in the commensal cellar spider Pholcus phalangioides to get insight into the causes affecting genetic variation in this species strictly associated with man. Our sampling consisted of 23 subpopulations collected over five urban regions in central Europe (distances ranged from 920 km to sites within the same building complex). Five variable allozyme loci showed significant interpopulation subdivision (theta=0.146) and isolation by distance over the area studied. On a regional scale (up to 70 km) significant differentiation was found, but the genetic pattern did not correlate with distance. Moreover, significant two-locus disequilibria were detected and a recent reduction in the effective population size was indicated within six sites. These results suggest that in P. phalangioides a high potential of dispersal and strong effects of drift within small, demographically unstable mating units seem to cause significant, but unpredictable genetic differentiation patterns at lower geographical scales. Our study documents strong effects of drift in a strictly commensal species outside the murine rodents.

Influence of clodronate on breast cancer cells in vitro

One of the major therapies of bone metastasis is administration of clodronate. But the influence of clodronate alone on tumour cells is not quite clear. Radiotherapy and administration of clodronate increasingly are used in combination. The influence of clodronate on radiosensitivity of tumour cells is not known.

METHODS

We used MDA-MB-435S and MCF-7 cells (breast cancer) in vitro and exposed the cells to clodronate in different concentrations and different short application times. In a second experiment we added graded doses of radiotherapy to the cell cultures. All experiments were done under standard conditions of the colony test.

RESULTS

At different concentrations and different incubation times clodronate is able to reduce the cell survival of MDA-MB-435S cells, but not of MCF-7 cells. Even very low concentrations of clodronate in the cell culture medium are sufficient to reduce the tumour cell survival of MDA-MB-435S down to 59%. This reduction is time and concentration dependent. Using irradiation, clodronate has definitively no influence on the radiosensitivity of MDA-MB-435S cells in vitro, but the shoulder of the survival curve of MCF-7 cells is markedly reduced, demonstrating reduced repair of sublethal radiation damage.

Comparative localization of mannose-6-phosphate receptor with 2,6sialyltransferase in HepG2 cells: an analysis by confocal double immunofluorescence microscopy

Recent advances in confocal immunofluorescent microscopy have led to significant improvements in delineating membrane-bounded organelles. In this study using HepG2 cells we focused on two functionally distinct but closely apposed organelles that have been difficult to distinguish by conventional immunofluorescent microscopy, namely the Golgi apparatus, the trans Golgi network (TGN) and late endosomes. The following markers were used: for the Golgi apparatus beta 1,4galactosyltransferase (gal-T), for the TGN, 2, 6(N)sialytransferase (sia-T) and for late endosomes/TGN, the mannose-6-phosphate/insulin growth factor II receptor (CIMPR). In addition, that part of the TGN previously shown to contain CIMPR was also identified using antibodies to the gamma-chain of the HA-1 adaptor (Klumperman et al. J. Cell Biol. 121, 997-1010 (1993)). True colocalization of intracellular antigens was ascertained by double staining of gal-T using both monoclonal and polyclonal antibodies. As previously reported, our results revealed essentially complete colocalization of gal-T and sia-T in this cell line. While the compartments containing CIMPR appeared to overlap with those containing sia-T by conventional immunofluorescence, both compartments were clearly distinct by double-label confocal microscopy. Differences between these organelles became more evident following treatment with brefeldin A. Finally, HA-1 gamma-chain was also localized to structures that were close to but clearly different from the sia-T-containing compartment. Absence of colocalization of CIMPR or HA-1 gamma-chain with sia-T indicates that these markers are enriched in distinct domains of the trans Golgi network.

Rat monoclonal antibodies differentiating between the Epstein-Barr virus nuclear antigens 2A (EBNA2A) and 2B (EBNA2B)

Rat monoclonal antibodies were produced against the C-terminus of Epstein-Barr virus nuclear antigens 2A (EBNA2A) and 2B (EBNA2B) expressed as bacterial trpE fusion proteins. The initial screening was performed using a soluble bacterial extract containing the fusion proteins. Positive hybridomas were confirmed by immunofluorescence on SF158 (Spodoptera frugiperda) insect cells infected with recombinant baculovirus (Autographa californica nuclear polyhedrosis virus) and expressing the complete EBNA2A or EBNA2B genes. We selected a panel of antibodies which reacted either with both antigens or specifically with EBNA2A or with EBNA2B. The antibodies were extensively characterized using immunoprecipitation, Western blotting, epitope mapping on synthesized peptide segments of EBNA2A, immunocytology, and immunohistology on both cryostat sections and paraffin sections of AIDS-associated primary central nervous system lymphomas.

Intake and fecal excretion of PCDDs, PCDFs, HCB and PCBs (138, 153, 180) in a breast-fed and a formula-fed infant

Intake and fecal excretion of PCDDs, PCDFs, HCB and PCBs (IUPAC Nos. 138, 153, 180) were measured in a breast-fed and a formula-fed infant at the age of 1 and 5 months. As expected, the intake of these compounds was clearly higher in the breast-fed infant. In this baby an almost complete absorption was observed for lower chlorinated PCDDs and PCDFs and also for HCB and PCBs, whereas for hepta- and octachlorinated PCDDs and PCDFs fecal excretion was considerably higher (from 20% up to nearly 100% of the intake). Due to low concentrations in diet and feces of the formula-fed infant an evaluation was possible only for a few compounds at the age of 5 months. These values were in the same range when compared with those of the breast-fed infant. For collection of feces new cotton diapers were used which were pre-extracted in order to reduce the levels of polychlorinated compounds. Unexpectedly, after washing the tissue a much higher contamination was observed which made a calculation of fecal excretion rates in the formula-fed infant at the age of 1 month impossible.

Immunological detection of proteins associated with the Epstein-Barr virus nuclear antigen 2A

The Epstein-Barr virus nuclear antigen 2A (EBNA-2A) has been strongly implicated in the EBV-mediated B-cell transformation process. Since EBNA-2A might exert this function through interaction with proteins of the infected cell, we studied the association of EBNA-2A with cellular proteins. Immunoprecipitation of EBNA-2A from 32P-labeled cell extracts separated by sucrose gradient centrifugation revealed the presence of phosphoproteins complexed with the two forms of the EBNA-2A sedimenting at 13 S and 34 S. Prominent bands were observed at 250, 170, 120, 110, 105, and 95 kDa with minor species at 78, 52, 45, 31, 26, 22 and 18 kDa. By "West-Western" or "Far-Western" blotting using EBNA-2A protein from insect cells as a probe we detected binding to proteins migrating with apparent molecular masses of about 200, 130, 110, 105, 95, and 31 kDa with minor species detectable at 90, 68, 50-55, 40, and 17 kDa. The protein with an apparent molecular mass of 31 kDa was identified by competition experiments as histone H1. Some of the EBNA-2A-complexed phosphoproteins, notably the proteins of 110 and 95 kDa, comigrated with the proteins detectable by "West-Western" analysis. The binding of EBNA-2A to the 130-kDa protein was stable against up to 1.5 M NaCl and could not be competed with histone H1. In a similar experiment, the less transforming EBNA-2B which is encoded by the subtype 2 virus bound to most of the proteins detected with EBNA-2A but with strongly reduced efficiency to the protein of 130 kDa indicating that this protein might be a target for EBNA-2 during EBV-mediated transformation.

Differences in the endosomal distributions of the two mannose 6-phosphate receptors

Multiple immunolabeling of cryosections was performed to compare the subcellular distributions of the two mannose 6-phosphate receptors (MPRs) involved in the intracellular targeting of lysosomal enzymes: the cation-dependent (CD) and cation-independent (CI) MPR. In two cell types, the human hepatoma cell line HepG2 and BHK cells double transfected with cDNA's encoding for the human CD-MPR and CI-MPR, we found the two receptors at the same sites: the trans-Golgi reticulum (TGR), endosomes, electron-dense cytoplasmic vesicles, and the plasma membrane. In the TGR the two receptors colocalized and were concentrated to the same extent in the same HA I-adaptor positive coated buds and vesicles. Endosomes were identified by the presence of exogenous tracers. The two MPR codistributed to the same endosomes, but semiquantitative analysis showed a relative enrichment of the CI-MPR in endosomes containing many internal vesicles. Two endosomal subcompartments were discerned, the central vacuole and the associated tubules and vesicles (ATV). We found an enrichment of CD-MPR over CI-MPR in the ATV. Lateral segregation of the two receptors within the plane of membranes was also detected on isolated organelles. Double immunolabeling for the CD-MPR and the asialoglycoprotein receptor, which mainly recycles between endosomes and the plasma membrane, revealed that these two receptors were concentrated in different subpopulations of endosomal ATV. The small GTP-binding protein rab4, which has been shown to mediate recycling from endosomes to the plasma membrane, was localized at the cytosolic face of many endosomal ATV. Quantitative analysis of double-immunolabeled cells revealed only a limited codistribution of the MPRs and rab4 in ATV. These data suggest that the two MPRs exit the TGR via the same coated vesicles, but that upon arrival in the endosomes CD-MPR is more rapidly than CI-MPR, segregated into ATV which probably are destined to recycle MPRs to TGR.

Expression of Epstein-Barr virus nuclear antigen 1,2A and 2B in the baculovirus expression system: serological evaluation of human antibodies to these proteins

The Epstein-Barr virus encoded nuclear antigens 1,2A, and 2B (EBNA 1, EBNA 2A, and EBNA 2B) were expressed in a baculovirus system. The full length recombinant proteins were recognized by polyclonal rabbit sera and by human sera. An immunofluorescence (IF) test for the differentiation between EBNA 1 and EBNA 2 antibodies in human sera was established with the expressed proteins. None of 55 sera of patients with infectious mononucleosis (IM) had anti-EBNA 1 antibodies while 36 of these sera had anti-EBNA 2A antibodies. Conversely, 47 of 51 sera from EBV-positive healthy carriers had anti-EBNA 1 antibodies and 18 of these sera had anti-EBNA 2A antibodies. The sensitivity and specificity of the EBNA 1 IF for the diagnosis of IM were higher as compared to conventional anti-complement immunofluorescence (ACIF). In the IF test differentiation between type A and type B EBV infection was only possible in sera from the IM patients. An immunoblot (IB) with low amounts of baculovirus expressed EBNA 2A and EBNA 2B antigen was carried out. Twenty-nine of 31 sera from IM patients or from healthy carriers with EBNA 2 antibodies reacted predominantly with EBNA 2A, whereas a known type B serum reacted strongly with EBNA 2B than with EBNA 2A.

Lysosomal acid phosphatase is internalized via clathrin-coated pits

The presence of lysosomal acid phosphatase (LAP) in coated pits at the plasma membrane was investigated by immunocytochemistry in thymidine kinase negative mouse L-cells (Ltk-) and baby hamster kidney (BHK) cells overexpressing human LAP (Ltk-LAP and BHK-LAP cells). Double immunogold labeling showed that at various stages of invaginating coated pits LAP colocalized with clathrin and plasma membrane adaptors (HA-2 adaptors). Quantitation of the immunogold label showed similar density of wild-type LAP in coated over non-coated areas of the plasma membrane, whereas an internalization-deficient, truncated mutant of LAP which lacks the cytoplasmic tail was less efficiently included into coated pits. Internalization of anti-LAP antibodies into endosomal vesicles was accompanied by rapid dissociation of the coat proteins as shown by an immunofluorescence assay. The role of clathrin-coated vesicles in internalization of LAP was further corroborated by microinjecting monoclonal antibodies against clathrin or HA-2 adaptors into BHK-LAP cells. Internalization of LAP as detected by an immunofluorescence assay was transiently blocked by microinjected antibodies against clathrin or HA-2 adaptors, whereas unrelated antibodies did not affect internalization. These data suggest that LAP is included into clathrin-coated pits of the plasma membrane for rapid internalization.

Endogenous Alkaloids in Man - Synthesis, Analytics, in vivo Identification, and Medicinal Importance*,1

The IN VITRO and IN VIVO condensation of endogenous (or administered) reactive amines and carbonyl compounds is reported, leading to alkaloid-type heterocycles. The spectrum of the presented "mammalian alkaloids" ranges from isoquinoline derivatives, via beta-carbolines, through to thiazolidines, arising from vitamin B (6), chloral, and glyoxylic acid, respectively. Formation of these compounds may occur accidentally, but might also be induced intentionally, as a therapy for metabolic diseases.

Antibodies against the cytoplasmic tail can differentiate between the quaternary forms of the Mr 46,000 mannose 6-phosphate receptor

An antiserum against a peptide of the cytoplasmic tail of the Mr 46,000 mannose 6-phosphate receptor is described which recognizes preferentially the tetrameric versus the dimeric form of this receptor. This indicates that the conformation of the cytoplasmic tail, which harbours signals necessary for the trafficking of the receptor, depends on the quaternary structure of the receptor.

Glycosylation of the Mr 46,000 mannose 6-phosphate receptor. Effect on ligand binding, stability, and conformation

Using site-directed mutagenesis the N-glycosylation sites of the Mr 46,000 mannose 6-phosphate receptor (MPR 46) were identified as asparagine residues 57, 83, 107, and 113. The two outer asparagines carry high mannose-type and the two inner asparagines carry complex-type oligosaccharides. The glycosylation mutants were analyzed for stability, binding activity, and subcellular distribution. Replacing asparagine 57, 83, or 107 by threonine decreased only the stability of the receptor. Replacing asparagine 113 by threonine decreased the stability and binding activity. Deletion of three or all four N-glycosylation sites led in addition to an accumulation of the mutant receptors in endoplasmic reticulum-like structures. Nonglycosylated MPR 46 synthesized in the presence of tunicamycin, thus preserving the asparagine residues, had a normal stability and high affinity binding. The decreased stability and binding activity of the receptor mutants is therefore due to the exchange of asparagine residues rather than to the loss of N-linked oligosaccharides. The nonglycosylated receptor, however, displayed a decreased conformational stability after solubilization as a single cycle of freezing and thawing reduced the binding activity to one-third of the control. Simultaneously, the receptor lost its quaternary structure. It is concluded from these results that the N-glycosylation of the receptor is required for the stability of a high affinity conformation, but not for the binding itself or the intracellular stability.

Quantitation of Mr 46000 and Mr 300000 mannose 6-phosphate receptors in human cells and tissues

A highly specific enzyme-linked immunosorbent assay for quantitation of the Mr 46000 Da and Mr 300000 Da mannose 6-phosphate receptors was developed. The assay allows to detect ng amounts of human mannose 6-phosphate receptors. Analysis of human cells and tissues revealed significant differences in their contents of the two mannose 6-phosphate receptors, normalized for total cell protein. The ratio of the two mannose 6-phosphate receptors also differed among cells and tissues, suggesting that their steady state concentrations are regulated independently.

Mannose 6-phosphate receptor dependent secretion of lysosomal enzymes

BHK and mouse L cells transfected with the cDNA for the human 46 kd mannose 6-phosphate receptor (MPR 46) secrete excessive amounts of newly synthesized mannose 6-phosphate containing polypeptides. The secretion is dependent on the amount, the recycling and the affinity for ligands of MPR 46. Incubation of transfected cells with antibodies blocking the binding site of MPR 46 reduces the secretion, and cotransfection with the cDNA for the human 300 kd mannose 6-phosphate (MPR 300) restores it to normal values. These results indicate that the two mannose 6-phosphate receptors compete for binding of newly synthesized ligands. In contrast to ligands bound to MPR 300, those bound to the MPR 46 are transported to and released at a site, e.g. early endosomes or plasma membrane, from where they can exit into the medium. Since antibodies blocking the binding site of MPR 46 reduce secretion also in non-transfected BHK and mouse L cells, at least part of the basal secretion of M6P-containing polypeptides is mediated by the endogenous MPR 46.

Endogenous alkaloids in man, VII: 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline--a potential chloral-derived indol alkaloid in man

The trichloromethyl tetrahydro-beta-carboline 5, an imaginable, chloral-derived mammalian indol "alkaloid", was prepared in high yields and was shown to be formed even under mild, physiological conditions, in aqueous medium. For its detection in low concentrations, a chromatographic procedure was elaborated. Furthermore, its potential metabolite 8 was synthesized for the first time.

Regulation of chromogranin B/secretogranin I and secretogranin II storage in GH4C1 cells

GH4C1 cells are a rat pituitary tumor cell strain in which the level of cellular prolactin (PRL) and PRL-containing secretory granules can be regulated by hormone treatment. The chromogranins/secretogranins (Sg) are a family of secretory proteins which are widely distributed in the secretory granules of endocrine and neuronal cells. In the present study, we investigated in GH4C1 cell cultures the regulation of the cell content of the Sg by immunoblotting and the relationship between the storage of Sg I and Sg II and PRL by double immunocytochemistry. GH4C1 cells grown in the presence of gelded horse serum, a condition in which these cells contain a low level of secretory granules, contained low levels of PRL, Sg I, and Sg II. Treatment of GH4C1 cells with a combination of 17 beta-estradiol, insulin, and epidermal growth factor for 3 days, known to induce a marked increase in the number of secretory granules, increased the cell contents of PRL, Sg I, and Sg II. To determine whether the induction of PRL was morphologically associated with that of the Sg, the distribution of PRL and the Sg was determined by double immunofluorescence microscopy. After hormone treatment, 54% of cells showed positive PRL immunoreactivity, fluorescence being extranuclear and consistent with staining of the Golgi zone and secretory granules. Forty-six percent of PRL-positive cells stained coincidently for Sg I, while 72% of the PRL cells were also reactive with anti-Sg II. To determine whether PRL storage was associated with storage of at least one of the Sg, cells were stained with anti-PRL and anti-Sg I and anti-Sg II together. Eighty-six percent of PRL cells stained for one or the other of the Sg. Therefore, PRL storage in GH4C1 cell cultures is closely but not completely associated with the storage of Sg I and/or II.

Assembly of the ligand-binding conformation of Mr 46,000 mannose 6-phosphate-specific receptor takes place before reaching the Golgi complex

The early steps in the biosynthesis of Mr 46,000 mannose 6-phosphate-specific receptor (MPR 46) have been studied by in vivo labeling of transfected BHK cells. The acquisition of phosphomannan-binding activity was compared with changes in protein structure and posttranslational modifications of MPR 46. Intramolecular disulfide bonds were formed before MPR 46 acquired a ligand-binding conformation. A conformational change that resulted in increased trypsin resistance, formation of highly immunogenic epitopes and assembly to noncovalently linked homodimers was observed almost simultaneously with the acquisition of ligand-binding activity. MPR 46 was shown to acquire ligand-binding activity before N-linked oligosaccharides were processed to complex-type forms. Maturation of the ligand-binding conformation was observed under conditions where transport to the Golgi was blocked by lowering the temperature to 16 degrees C, or by addition of brefeldin A or dinitrophenol to the medium at 37 degrees C. This suggests that receptor maturation and assembly take place before reaching the Golgi complex. The affinity towards phosphomannan-containing ligands was shown to be similar for the high-mannose and complex-glycosylated forms of MPR 46.

Occurrence of tyrosine sulfate in proteins--a balance sheet. 1. Secretory and lysosomal proteins

1. The abundance of tyrosine sulfate in secretory proteins and in various classes of cellular proteins has been quantified and compared to protein-bound carbohydrate sulfate. 2. HepG2 cells and fibroblasts, two cell types showing only the constitutive pathway of secretion, and PC12 cells, which show both the constitutive and the regulated pathway of secretion, were subjected to pulse-chase and/or long-term labelling with [35S]sulfate and [3H]tyrosine, followed by analysis of proteins in the cells and medium. Under both conditions of labelling, 65-92% of the protein-bound tyrosine sulfate and 44-84% of the protein-bound carbohydrate sulfate were found to be secretory. In HepG2 cells, the frequency of sulfation of tyrosine residues, which can be determined independently from protein abundance and the rate of protein synthesis, was 8-22 times higher in proteins secreted into the medium than in cellular proteins. 3. All cell lines studied contained significant amounts, not only of carbohydrate sulfate, but also of tyrosine sulfate in specific cellular proteins. As shown for fibroblasts, these tyrosine-sulfated proteins were retained within the cells for at least 100 min of chase following a pulse with [35S]sulfate and were almost completely recovered in a light membrane fraction after subcellular fractionation. 4. Lysosomes were found to contain small, but significant, amounts of protein-bound tyrosine sulfate in addition to protein-bound carbohydrate sulfate. Protein-bound tyrosine sulfate in lysosomes reached a peak at 20 min of chase and rapidly disappeared thereafter, whereas protein-bound carbohydrate sulfate accumulated after 20 min of chase. Examination of the known sequences of eleven lysosomal enzymes revealed the presence of potential tyrosine sulfation sites in five of them. 5. Our results show that secretory proteins are the most abundant, but not exclusive, in vivo substrates for tyrosine sulfation and suggest the presence of soluble tyrosine-sulfated proteins in lysosomes and other, as yet unidentified, organelles of the secretory pathway. In the following paper in this journal we describe the abundance of tyrosine sulfate in integral membrane proteins.

Occurrence of tyrosine sulfate in proteins--a balance sheet. 2. Membrane proteins

1. The abundance of tyrosine sulfate in membrane proteins was quantified in four different cell lines and compared to that in soluble cellular and secreted proteins. 2. Upon metabolic labelling of HepG2, Ltk-, AtT20 and PC12 cells with [35S]sulfate or [3H]tyrosine, a fraction enriched in integral membrane proteins was found to contain small, but significant, amounts of protein-bound tyrosine sulfate (up to 2.5% of the total cellular plus secreted protein-bound tyrosine sulfate). On the other hand, the frequency of sulfation of tyrosine residues of membrane proteins was within the same order of magnitude as that of secreted proteins, indicating that the low abundance of tyrosine sulfate in membrane proteins was largely a reflection of the low abundance of these proteins themselves. Consistent with this conclusion were the results of an analysis showing that 14 out of 32 selected membrane-spanning proteins contain potential tyrosine sulfation sites. 3. In HepG2 cells, three tyrosine-sulfated integral membrane glycoproteins of molecular mass 100, 125 and 150 kDa were identified. Characterization of the 150-kDa tyrosine-sulfated membrane protein revealed that it was protected from proteolysis in intact cells, suggesting a localization in an intracellular organelle. 4. Together with the results reported in the preceding paper in this journal, our data suggest that tyrosine sulfation occurs in various classes of trans-Golgi-derived proteins, soluble as well as membrane, and extracellularly exposed as well as intracellularly retained, proteins. This suggests that tyrosine sulfation may have a variety of physiological functions, depending on the individual tyrosine-sulfated protein or protein class.