Pathological examination of an explanted phakic posterior chamber intraocular lens

PURPOSE

To report the clinicopathological correlation of an explanted phakic posterior chamber intraocular lens (PPC IOL) and to study the conformation of this lens implanted into human eyes obtained postmortem.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Three silicone PPC IOLs were explanted. One lens, explanted from a 38-year-old woman with complicated cataract, was submitted for pathological analysis. In addition to gross and scanning electron microscopy (SEM), the lens was studied after experimental implantation in human eyes obtained postmortem using frontal, posterior, and side-view techniques.

RESULTS

Although gross and SEM showed that the IOL was well polished, examination of the lens in human cadaver eyes showed it was oversized and poorly fixated. It was relatively bulky in its anterior-posterior dimension and revealed evidence of significant contact with the iris and crystalline lens.

CONCLUSIONS

This study illustrates many pitfalls to be avoided in the design of a plate PPC IOL. The lens in this report was too large, and instead of ciliary sulcus fixation, it showed poor fixation through the zonules onto the posterior face of the pars plicata. Present and future PPC IOLs should be submitted for similar preclinical studies to clarify the type and site of fixation.

Different apoptotic pathways are induced from various intracellular sites by tetraphenylporphyrins and light

The induction of apoptosis from different intracellular sites was studied by exposing V79 Chinese hamster fibroblasts to photodynamic therapy (PDT) with various porphyrins and light. The effects of two lipophilic, intracellular membrane-localized porphyrins, tetra(3-hydroxyphenyl)porphyrin (3THPP) and Photofrin, were compared with that of two sulphonated meso-tetraphenylporphines (TPPS2a and TPPS4), which are taken up into lysosomes by endocytosis. Apoptotic fractions induced by the various dyes and light were quantified by flow cytometry using the terminal deoxynucleotidyl transferase (TdT) assay. Cell fragmentation was measured in parallel, while the nuclear morphology of apoptotic cells was studied by fluorescence microscopy. Different kinetics were found for the induction of DNA strand breaks characteristic of apoptotic cells. PDT-induced damage to membranes resulted in an increasing number of apoptotic cells for about 12 h after PDT After damage to lysosomes, apoptotic cells were not detected until more than 12 h after PDT. Furthermore, apoptotic bodies were not observed after PDT-induced damage to intracellular membranes, whereas apoptosis induced from lysosomal sites was characterized by extensive cell fragmentation. Cell fragmentation occurred in combination with or in the absence of nuclear fragmentation. The results support the idea that the degradation phase of apoptosis can consist of a sequence of independent steps rather than a common final pathway.

Fructus corni attenuates oxidative stress in macrophages and endothelial cells

The antioxidant effect of a Chinese medicinal herb, Fructus corni extract (FCE), was investigated using models of oxidative stress in macrophages and vascular endothelial cells. Murine macrophages (J774) were incubated with FCE at 37 degrees C and 5% CO2 for 1 hr. Oxidative burst was triggered by zymosan and measured with a fluorescent probe. FCE exhibited a concentration- dependent suppression of oxidative burst. Confluent monolayers of bovine pulmonary artery endothelial cells (PAEC) were preincubated with FCE for 20 hrs, washed, and then exposed to an organic oxidant t-butyl hydroperoxide (tBHP) for 2 hrs. Cell viability was assessed by methylthiazol tetrazolium (MTT) assay, and cell injury by the release of intracellular lactate dehydrogenase (LDH). Lipid peroxidation products of PAEC were determined by measuring thiobarbituric acid-reactive substances (TBARS). Exposure of PAEC to tBHP resulted in decreased cell viability, increased LDH release, and elevated TBARS. Preincubation of PAEC with FCE significantly reversed these changes. Our results demonstrated that FCE can protect vascular endothelial cells from oxidant injury. The data thus suggest that Fructus corni may be useful for the prevention and/or treatment of disorders associated with oxidative damage.

Production of protoporphyrin IX induced by 5-aminolevulinic acid in transplanted human colon adenocarcinoma of nude mice can be increased by ultrasound

BALB/c nude mice bearing WiDr human colon adenocarcinoma were used to determine the effect of ultrasound on the production of 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) both in the tumors and in skin overlying the tumors. Ultrasound (1 MHz) with pulsed irradiation at an average intensity of 3 W/cm2 was given 10 min to the tumor area 10 min after administration of ALA (20% in an oil-in-water emulsion applied topically on the surface of the tumor for 30 min to 3 hr). An approximately 45% increase in the amount of PpIX produced by ALA in the tumors was obtained within 1 to 2 hr following ultrasound treatment. In particular, 1 hr after ultrasound treatment, the amount of PpIX in the tumors was at the same level as that 3 hr after ALA application alone. However, pulsed ultrasound irradiation for 5 min or continuous irradiation for 5 or 10 min had no significant effect on the production of PpIX by the tumor 1 hr after topical ALA application. Furthermore, in most cases, the amount of PpIX in the tumors was significantly decreased when ultrasound was given immediately before ALA application. There was no significant change in the ratio of the amount of PpIX in tumor to that in skin after ultrasound treatment. Most likely, the distribution of PpIX fluorescence in the tumors treated with ultrasound was more homogeneous than that in the tumors given ALA only. Our results provide a theoretical basis for possible clinical use of ultrasound-combined ALA or ALA based photodynamic therapy.

Susceptibility to esophageal cancer and genetic polymorphisms in glutathione S-transferases T1, P1, and M1 and cytochrome P450 2E1

Genetic polymorphisms in enzymes involved in carcinogen metabolism have been shown to influence susceptibility to cancer. Cytochrome P450 2E1 (CYP2E1) is primarily responsible for the bioactivation of many low molecular weight carcinogens, including certain nitrosamines, whereas glutathione S-transferases (GSTs) are involved in detoxifying many other carcinogenic electrophiles. Esophageal cancer, which is prevalent in China, is hypothesized to be related to environmental nitrosamine exposure. Thus, we conducted a pilot case-control study to examine the association between CYP2E1, GSTM1, GSTT1, and GSTP1 genetic polymorphisms and esophageal cancer susceptibility. DNA samples were isolated from surgically removed esophageal tissues or scraped esophageal epithelium from cases with cancer (n = 45), cases with severe epithelial hyperplasia (n = 45), and normal controls (n = 46) from a high-risk area, Linxian County, China. RFLPs in the CYP2E1 and the GSTP1 genes were determined by PCR amplification followed by digestion with RsaI or DraI and Alw26I, respectively. Deletion of the GSTM1 and GSTT1 genes was examined by a multiplex PCR. The CYP2E1 polymorphism detected by RsaI was significantly different between controls (56%) and cases with cancer (20%) or severe epithelial hyperplasia (17%; P < 0.001). Persons without the RsaI variant alleles had more than a 4-6-fold risk of developing severe epithelial hyperplasia (adjusted odds ratio, 6.0; 95% confidence interval, 2.3-16.0) and cancer (adjusted odds ratio, 4.8; 95% confidence interval, 1.8-12.4). Polymorphisms in the GSTs were not associated with increased esophageal cancer risk. These results indicate that CYP2E1 may be a genetic susceptibility factor involved in the early events leading to the development of esophageal cancer.

[FTIR study on the normal and tumor gastrointestinal tissues]

Series of cancer tissues and corresponding normal tissues of gastrointestinal tract (stomach, colon, esophagus) were studied by FTIR technique and the results showed the analogy of the spectra for the cancer tissues, while the spectra of normal tissues can be classified into three kinds. The secondary structures of protein were obtained by using deconvolution and curve-fitting techniques with Amide I bands and the results showed that the contents of alpha -helix and beta-sheet are different between the normal and cancer tissues.

Fructus corni enhances endothelial cell antioxidant defenses

1. The present study determined the effects of Fructus corni extract (FCE) on the levels of hydrogen peroxide (H2O2) and superoxide anion (O2-), on the glutathione (GSH) redox cycle and on the activities of antioxidant enzymes in bovine pulmonary artery endothelial cells (PAECs). 2. Confluent monolayers of PAECs were incubated with FCE, and oxidative stress was triggered by hypoxanthine and xanthine oxidase (to induce H2O2) or H2O2 (to induce O2-). 3. FCE exhibited a concentration-dependent suppression of H2O2 and O2-. 4. It modulated the GSH redox cycle by increasing the intracellular GSH content, the activities of GSH peroxidase and GSH disulfide reductase, and by decreasing the intracellular level of GSH disulfide. 5. It also increased the activities of superoxide dismutase and catalase. 6. These results demonstrate that FCE can promote a protective antioxidant defense state by affecting some important enzymatic and nonenzymatic oxidant-scavenging systems and may thus be useful for the prevention or treatment of disorders associated with oxidative damage.

Posterior capsular plaque: a common feature of cataract surgery in the developing world

PURPOSE

To study the histopathologic findings of posterior capsular plaque, a lesion that is discovered frequently in eyes undergoing cataract surgery in the developing world.

METHODS

Two hundred human crystalline lenses removed from 200 eyes of 200 patients who underwent intracapsular cataract extraction at Sagarmatha Choudhary Eye Hospital in Nepal were analyzed histopathologically.

RESULTS

Forty-nine lenses (24.5%) had a posterior capsular plaque. We confirm that the posterior plaques are composed of collagen that stains positively for Masson trichrome stain and that forms after pseudofibrous metaplasia of lens cells along the posterior capsule. The plaques form in a fashion analogous to a healing process.

CONCLUSIONS

We postulate that posterior capsular plaques result from posterior migration of epithelium and pseudofibrous metaplasia of lens epithelium. Most of the posterior capsular plaques are minute and not likely to affect vision. However, a small percentage of plaques are thicker and are likely to impair vision after extracapsular cataract surgery.

Mini-haptics to improve capsular fixation of plate-haptic silicone intraocular lenses

PURPOSE

To evaluate the effects of a new mini-haptic design on the strength and stability of capsular bag fixation of plate-haptic silicone intraocular lenses (IOLs) and determine whether this design encourages the growth of regenerating lens material or fibrous tissue around the haptic biomaterial and thus improves lens fixation in the capsular bag.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Department of Ophthalmology, Charleston, South Carolina, USA.

METHODS

Six rabbits had bilateral continuous curvilinear capsulorhexis, phacoemulsification, and plate-haptic silicone IOL implantation. Each rabbit had a small-hole plate IOL (Chiron C10UB) implanted in the right eye and a mini-haptic plate IOL (Chiron C40UB) in the left eye. All rabbits were killed at 2 months. The force required to extract one haptic from the capsular bag was measured with a digital force gauge. Histopathologic analysis was performed on all specimens.

RESULTS

The mini-haptic style IOLs required significantly more extraction force than the small-hole design (P = .011). Histopathologically, proliferating lens epithelial cells were observed growing circumferentially around the mini-haptics, causing a 360 degree synechia formation. This formation did not occur with the conventional small-hole plate IOLs used as the control.

CONCLUSIONS

Lens epithelial cell proliferation around the mini-haptics significantly improved capsular bag fixation of the plate-haptic silicone IOL. This should decrease the incidence of clinical decentration and dislocation.

Fixation elements on plate intraocular lens: large positioning holes to improve security of capsular fixation

OBJECTIVE

This study aimed to evaluate in rabbit eyes the effects of large positioning holes in one-piece silicone plate-haptic intraocular lenses (IOLs) with respect to security of capsular bag fixation. Mechanical strength of capsular fixation is correlated with the histologic findings of regenerating lens material and fibrous tissue ingrowth through the positioning holes on silicone plate IOLs, comparing capsules implanted with large-hole style plate IOLs to fellow capsules implanted with small-hole style plate IOLs.

DESIGN

The study design was a prospective, randomized, experimental study.

PARTICIPANTS

A total of 40 fellow capsular bags from 20 New Zealand white rabbits were examined. Capsules implanted with conventional small-hole silicone plate IOLs were used as the control in all pairs of fellow capsules.

INTERVENTION

Phacoemulsification and implantation of a silicone plate IOL with small positioning holes in one eye and implantation of a silicone plate IOL with large positioning holes in the fellow eye were measured. All rabbits were killed at 2 months. The force required to extract the IOLs from the capsular bag was measured. All capsular bags underwent histopathologic analysis.

MAIN OUTCOME MEASURES

Extraction force measurements and histopathologic examination, comparing capsules implanted with small-hole plate IOLs with fellow capsules implanted with large-hole plate IOLs, were measured.

RESULTS

The large-hole style IOL required significantly more force to extract from the capsular bag compared to the conventional small-hole style (P = 0.003). Histologically, proliferating lens epithelial material and fibrous tissue were observed growing through all of the large positioning holes (synechia formation) but not through any of the small positioning holes.

CONCLUSIONS

Silicone plate IOLs with large positioning holes become affixed more firmly within the capsular bag compared to conventional small-hole plate IOLs. These findings suggest that large holes in silicone plate IOLs allow for superior capsular bag fixation. This should reduce the rates of decentration and dislocation.

[Use of 5-aminolevulinic acid in photochemotherapy and fluorescence diagnostics]

5-aminolevulinic acid is an early intermediate product in the synthesis of heme. Some of the enzymes in the heme synthesis chain have altered activities in tumor tissue, so that application of 5-aminolevulinic acid leads to an accumulation of protoporphyrin IX in tumors. This molecule absorbs light and acts as a potent photosensitizer; tumors containing the compound can therefore be destroyed by light. 5-aminolevulinic acid based photochemotherapy is presently being employed in the treatment of thin basal cell carcinomas in many countries. The cosmetic result of this treatment is excellent. Furthermore, it is a simple and inexpensive form of treatment with curative rates comparable to those of established therapy modalities. Experimentally, a number of other malignant lesions reachable by light via optical fibers are being treated. Since protoporphyrin IX has a characteristic red fluorescence, 5-aminolevulinic acid can also be applied for diagnostic purposes.

Apoptosis induction by different pathways with methylene blue derivative and light from mitochondrial sites in V79 cells

The importance of mitochondria for the induction of apoptosis by photodynamic therapy (PDT) was studied with a new photosensitizing dye, methylene blue derivative (MBD), and light. By using fluorescence microscopy and by measuring the MBD-PDT-induced inhibition of specifically subcellularly localized marker enzymes, we show that MBD is localized in mitochondria and not in lysosomes, endoplasmic reticulum or Golgi apparatus of V79 Chinese hamster fibroblasts. Cellular uptake kinetics and fluorescence properties of the dye in cells were characterized. Cell death was studied by a cell survival assay and by flow cytometry of cells stained using the terminal deoxynucleotidyl transferase (TdT) assay. MBD with light induced cell death by apoptosis via 2 different pathways, one rapid and one delayed, depending on the amount of dye in the cells. Cells treated with an MBD concentration higher than 0.05 microg/ml died by apoptosis within 3 hr after light exposure. At a concentration of 0.05 microg/ml MBD, cell death was induced slowly, and apoptotic cells appeared increasingly from the second day after PDT. Combination studies with 2-deoxyglucose (2-DOG) and carbonylcyanide-m-chlorophenylhydrazone (CCCP), inhibitors of glycolysis and oxidative phosphorylation, respectively, indicated that MBD and light inhibited mitochondrial oxidative phosphorylation. Abolishment of both energy sources led to cell death by necrosis within 6 hr. Inhibition of glycolysis alone induced apoptosis between 3 and 6 hr, while inhibition of mitochondrial oxidative phosphorylation alone led to delayed apoptosis within days.

[Genetic polymorphisms of cytochrome P450 2E1 and glutathione S-transferase P1 and susceptibility to esophageal cancer]

OBJECTIVES

To study the association between genetic polymorphisms of cytochrome P4502E1 (CYP2E1) and/or glutathione S-transferase P1 (GSTP1) and susceptibility to esophageal cancer.

METHODS

Genotyping of CYP2E1 and GSTP1 was performed using PCR-based RFLP analysis on DNA isolated from surgically removed esophageal tissues or scraped esophageal epithelium from cancer cases (n = 45), severe epithelial hyperplasia cases (n = 45), and normal controls (n = 45).

RESULTS

The variant genotypes (c1/c2 and c2/c2) detected by RsaI digestion was found in 17% of epithelial hyperplasia cases, 20.0% of esophageal cancer cases and 55.6% of controls, with the differences being statistically significant (P < 0.001). Subjects carrying wild-type genotype of CYP2E1 had more than 5-fold risk for developing severe epithelial hyperplasia (odds ratio, OR = 5.78; 95% confidence interval, CI = 2.2-15.2) and esophageal cancer (OR = 5.00; 95% CI = 2.0-12.8). No association with the risk of severe epithelial hyperplasia and esophageal cancer was observed for the DraI polymorphism of CYP2E1 or for the Awl26I polymorphism of GSTP1.

CONCLUSION

CYP2E1 is a genetic susceptibility factor involved in the early events for esophageal carcinogenesis.

[Deletion of MTS1/p16 gene in human esophageal carcinoma]

OBJECTIVE

To investigate the alteration of MTS1/p16 gene in human esophageal carcinoma.

METHODS

A total of 60 human esophageal tissue specimens, comprising 30 squamous-cell carcinomas and 30 tumor-adjacent tissue specimens, were examined for homozygous deletion of p16 gene by using Southern blot hybridization and PCR method.

RESULTS

The results showed that no deletions were detected in 30 tumor-adjacent tissue samples. However, of 30 esophageal carcinoma specimens, 7 were found negative for p16 gene in Southern blot assay, and the deletion of the p16 gene in 5 samples were confirmed by PCR with a 16.7% p16 gene deletion rate.

CONCLUSION

These data suggest that MTS1/p16 gene alterations may play a role in the progression of human esophageal carcinoma.

Potent induction of a neutrophil and eosinophil-rich infiltrate in vivo by human mast cell tryptase: selective enhancement of eosinophil recruitment by histamine

Tryptase is the most abundant protein constituent of the secretory granules of human mast cells, but little is known of the contribution of this serine proteinase in acute allergic reactions. We have purified tryptase from human lung tissue by immunoaffinity procedures, and have investigated its potential to provoke an inflammatory infiltrate in vivo. Within 6 h of injection into the skin of guinea pigs, the accumulation of large numbers of neutrophils and eosinophils was observed, and those eosinophils closest to the injection site were partially degranulated. Similarly, injection of tryptase into the peritoneum of mice, even in quantities as low as 5 ng, stimulated the ingress of neutrophils. The response was dose dependent at 3, 6, and 16 h, with increases in median numbers of up to 400-fold. At the later time points eosinophil numbers were increased by up to 10-fold, and there were elevations also in the numbers of lymphocytes and macrophages. In both models, the actions of tryptase appeared to be dependent on an intact catalytic site. Coinjection of heparin with tryptase had relatively little effect on tryptase-induced responses. On the other hand, although histamine did not itself stimulate cell accumulation, over a range of concentrations it altered the cellular composition of the infiltrate induced by tryptase. Addition of histamine to tryptase provoked selective increases in eosinophil numbers of up to fivefold in the mouse peritoneum. Tryptase may provide an important stimulus for granulocyte recruitment in allergic disease.

Potent induction of a neutrophil and eosinophil-rich infiltrate in vivo by human mast cell tryptase: selective enhancement of eosinophil recruitment by histamine

Tryptase is the most abundant protein constituent of the secretory granules of human mast cells, but little is known of the contribution of this serine proteinase in acute allergic reactions. We have purified tryptase from human lung tissue by immunoaffinity procedures, and have investigated its potential to provoke an inflammatory infiltrate in vivo. Within 6 h of injection into the skin of guinea pigs, the accumulation of large numbers of neutrophils and eosinophils was observed, and those eosinophils closest to the injection site were partially degranulated. Similarly, injection of tryptase into the peritoneum of mice, even in quantities as low as 5 ng, stimulated the ingress of neutrophils. The response was dose dependent at 3, 6, and 16 h, with increases in median numbers of up to 400-fold. At the later time points eosinophil numbers were increased by up to 10-fold, and there were elevations also in the numbers of lymphocytes and macrophages. In both models, the actions of tryptase appeared to be dependent on an intact catalytic site. Coinjection of heparin with tryptase had relatively little effect on tryptase-induced responses. On the other hand, although histamine did not itself stimulate cell accumulation, over a range of concentrations it altered the cellular composition of the infiltrate induced by tryptase. Addition of histamine to tryptase provoked selective increases in eosinophil numbers of up to fivefold in the mouse peritoneum. Tryptase may provide an important stimulus for granulocyte recruitment in allergic disease.

[Penetration of ciprofloxacin and cefoperazone into human pancreas]

Major pancreatic infection is responsible for more than 80% of deaths in patients with acute pancreatitis. Therefore, the role of antimicrobial drugs in the prevention and treatment of secondary parcreatic infection is very important. The choice of antimicrobial drugs must be based upon the ability of the drug to exceed the therapeutic concentration in pancreas for the common pathogens. The penetration of ciprofloxacin and cefoperazone into pancreas was investigated in ten patients who had undergone pancreatoduodenectomy. The pancreatic juice was temporarily diverted to the exterior via a panoreatic duct catheter. The pancreatic tissue was obtained intraoperatively and pancreatic juice was drained postoperatively. The antimicrobial drug concentrations were determined by high-performance liquid chromatography. The concentrations of ciprofloxacin and cefoperazone in pancreatic juice were 44% and 17%, respectively, of those in serum, and exceeded the in vitro concentration (MIC-90) for most bacteria associated with pancreatic infections. The result indicates that ciprofloxacin and cefoprazone appear to be appropriate for both prophylaxis and therapy of secondary pancreatic infections.

Security of capsular fixation: small-versus large-hole plate-hepatic lenses

PURPOSE

To assess the effect of relatively large positioning holes on the security of capsular bag fixation of plate-haptic silicone intraocular lenses (IOLs).

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

This study tested the hypothesis that larger holes allow ingrowth of lens material, fibrous tissue, or both through them, which helps fixate the lens more firmly in the capsular bag. Five rabbits had bilateral continuous curvilinear capsulorhexis, phacoemulsification, and implantation of a plate-haptic silicone IOL. An IOL with a small, round positioning hole (Staar AA-4203V) was implanted in the right eye in each rabbit, and a large-hole IOL (Staar AA-4203VF) was implanted in the left eye. After 2 months, all rabbits were killed. The force required to extract one haptic from the capsular bag was measured with a digital force meter. All eyes had histopathological analysis.

RESULTS

It was slightly more difficult to extract a large-hole IOL from the capsular bag, although this trend was not statistically significant. However, histopathological analysis consistently showed 360 degree synechia formation through the holes, showing that the IOL could be securely fixed in position.

CONCLUSIONS

Proliferation of lens epithelial cells through a large positioning hole in a plate-haptic silicone IOL may improve the long-term security of capsular bag fixation. This will help reduce the incidence of IOL decentration and dislocation.

[Studies on expansion ex vivo of murine bone marrow cells and its hematopoietic reconstitution capacity]

OBJECTIVE

To investigate the effects of stem cell factor (SCF) in combination with interleukin-1 (IL-1) or/and interleukin-3 (IL-3) on ex vivo expansion of 5FU treated bone marrow cells and hematopoietic recovery in lethally irradiated mice transplanted with the expanded cells.

METHODS

5FU treated bone marrow cells (d3-5FU-BMC) were cultured in a cytokines-containing medium, and the net increments of CFU-GM and high proliferative potential colony forming cell (HPP-CFC) were evaluated.

RESULTS

CFU-GM increased by 33.7 +/- 18.1- or 18.1 +/- 6.3- fold, and HPP-CFC by 17.8 +/- 10.5- or 12.7 +/- 9.1- fold, respectively, in cultures containing SCF with IL- or IL-3, as compared with that in control; while SCF alone had little effect. Compared with fresh d3-5FU-BMC, transplantation of the expanded bone marrow cells accelerated the recovery of recipients' peripheral blood cell counts by 1 approximately 3 days and increased the survival rate of the transplanted animals (d3-5FU-BMC group 50% vs expansion group 8U approximately 100%).

CONCLUSION

SCF in combination with IL-1 or IL-3 synergetically ex vivo expands hematopoietic cells. Transplantation of the expanded bone marrow cells accelerates the recipient's hematopoietic reconstitution.

5-Aminolevulinic acid-based photodynamic therapy. Clinical research and future challenges

BACKGROUND

Photodynamic therapy (PDT) for cancer patients has developed into an important new clinical treatment modality in the past 25-years. PDT involves administration of a tumor-localizing photosensitizer or photosensitizer prodrug (5-aminolevulinic acid [ALA], a precursor in the heme biosynthetic pathway) and the subsequent activation of the photosensitizer by light. Although several photosensitizers other than ALA-derived protoprophyrin IX (PpIX) have been used in clinical PDT, ALA-based PDT has been the most active area of clinical PDT research during the past 5 years. Studies have shown that a higher accumulation of ALA-derived PpIX in rapidly proliferating cells may provide a biologic rationale for clinical use of ALA-based PDT and diagnosis. However, no review updating the clinical data has appeared so far.

METHODS

A review of recently published data on clinical ALA-based PDT and diagnosis was conducted.

RESULTS

Several individual studies in which patients with primary nonmelanoma cutaneous tumors received topical ALA-based PDT have reported promising results, including outstanding cosmetic results. However, the modality with present protocols does not in general, appear to be superior to conventional therapies with respect to initial complete response rates and long term recurrence rates, particularly in the treatment of nodular skin tumors. Topical ALA-PDT does have the following advantages over conventional treatments: it is noninvasive; it produces excellent cosmetic results; it is well tolerated by patients; it can be used to treat multiple superficial lesions in short treatment sessions; it can be applied to patients who refuse surgery or have pacemakers and bleeding tendency; it can be used to treat lesions in specific locations, such as the oral mucosa or the genital area; it can be used as a palliative treatment; and it can be applied repeatedly without cumulative toxicity. Topical ALA-PDT also has potential as a treatment for nonneoplastic skin diseases. Systemic administration of ALA does not seem to be severely toxic, but the advantage of using this approach for PDT of superficial lesions of internal hollow organs is still uncertain. The ALA-derived porphyrin fluorescence technique would be useful in the diagnosis of superficial lesions of internal hollow organs.

CONCLUSIONS

Promising results of ALA-based clinical PDT and diagnosis have been obtained. The modality has advantages over conventional treatments. However, some improvements need to be made, such as optimization of parameters of ALA-based PDT and diagnosis; increased tumor selectivity of ALA-derived PpIX; better understanding of light distribution in tissue: improvement of light dosimetry procedure; and development of simpler, cheaper, and more efficient light delivery systems.

5-Aminolevulinic acid-based photodynamic therapy. Clinical research and future challenges

BACKGROUND

Photodynamic therapy (PDT) for cancer patients has developed into an important new clinical treatment modality in the past 25-years. PDT involves administration of a tumor-localizing photosensitizer or photosensitizer prodrug (5-aminolevulinic acid [ALA], a precursor in the heme biosynthetic pathway) and the subsequent activation of the photosensitizer by light. Although several photosensitizers other than ALA-derived protoprophyrin IX (PpIX) have been used in clinical PDT, ALA-based PDT has been the most active area of clinical PDT research during the past 5 years. Studies have shown that a higher accumulation of ALA-derived PpIX in rapidly proliferating cells may provide a biologic rationale for clinical use of ALA-based PDT and diagnosis. However, no review updating the clinical data has appeared so far.

METHODS

A review of recently published data on clinical ALA-based PDT and diagnosis was conducted.

RESULTS

Several individual studies in which patients with primary nonmelanoma cutaneous tumors received topical ALA-based PDT have reported promising results, including outstanding cosmetic results. However, the modality with present protocols does not in general, appear to be superior to conventional therapies with respect to initial complete response rates and long term recurrence rates, particularly in the treatment of nodular skin tumors. Topical ALA-PDT does have the following advantages over conventional treatments: it is noninvasive; it produces excellent cosmetic results; it is well tolerated by patients; it can be used to treat multiple superficial lesions in short treatment sessions; it can be applied to patients who refuse surgery or have pacemakers and bleeding tendency; it can be used to treat lesions in specific locations, such as the oral mucosa or the genital area; it can be used as a palliative treatment; and it can be applied repeatedly without cumulative toxicity. Topical ALA-PDT also has potential as a treatment for nonneoplastic skin diseases. Systemic administration of ALA does not seem to be severely toxic, but the advantage of using this approach for PDT of superficial lesions of internal hollow organs is still uncertain. The ALA-derived porphyrin fluorescence technique would be useful in the diagnosis of superficial lesions of internal hollow organs.

CONCLUSIONS

Promising results of ALA-based clinical PDT and diagnosis have been obtained. The modality has advantages over conventional treatments. However, some improvements need to be made, such as optimization of parameters of ALA-based PDT and diagnosis; increased tumor selectivity of ALA-derived PpIX; better understanding of light distribution in tissue: improvement of light dosimetry procedure; and development of simpler, cheaper, and more efficient light delivery systems.

5-Aminolevulinic acid-based photodynamic therapy. Clinical research and future challenges

BACKGROUND

Photodynamic therapy (PDT) for cancer patients has developed into an important new clinical treatment modality in the past 25-years. PDT involves administration of a tumor-localizing photosensitizer or photosensitizer prodrug (5-aminolevulinic acid [ALA], a precursor in the heme biosynthetic pathway) and the subsequent activation of the photosensitizer by light. Although several photosensitizers other than ALA-derived protoprophyrin IX (PpIX) have been used in clinical PDT, ALA-based PDT has been the most active area of clinical PDT research during the past 5 years. Studies have shown that a higher accumulation of ALA-derived PpIX in rapidly proliferating cells may provide a biologic rationale for clinical use of ALA-based PDT and diagnosis. However, no review updating the clinical data has appeared so far.

METHODS

A review of recently published data on clinical ALA-based PDT and diagnosis was conducted.

RESULTS

Several individual studies in which patients with primary nonmelanoma cutaneous tumors received topical ALA-based PDT have reported promising results, including outstanding cosmetic results. However, the modality with present protocols does not in general, appear to be superior to conventional therapies with respect to initial complete response rates and long term recurrence rates, particularly in the treatment of nodular skin tumors. Topical ALA-PDT does have the following advantages over conventional treatments: it is noninvasive; it produces excellent cosmetic results; it is well tolerated by patients; it can be used to treat multiple superficial lesions in short treatment sessions; it can be applied to patients who refuse surgery or have pacemakers and bleeding tendency; it can be used to treat lesions in specific locations, such as the oral mucosa or the genital area; it can be used as a palliative treatment; and it can be applied repeatedly without cumulative toxicity. Topical ALA-PDT also has potential as a treatment for nonneoplastic skin diseases. Systemic administration of ALA does not seem to be severely toxic, but the advantage of using this approach for PDT of superficial lesions of internal hollow organs is still uncertain. The ALA-derived porphyrin fluorescence technique would be useful in the diagnosis of superficial lesions of internal hollow organs.

CONCLUSIONS

Promising results of ALA-based clinical PDT and diagnosis have been obtained. The modality has advantages over conventional treatments. However, some improvements need to be made, such as optimization of parameters of ALA-based PDT and diagnosis; increased tumor selectivity of ALA-derived PpIX; better understanding of light distribution in tissue: improvement of light dosimetry procedure; and development of simpler, cheaper, and more efficient light delivery systems.

Silicone oil adhesion to intraocular lenses: an experimental study comparing various biomaterials

PURPOSE

To perform an in vitro experimental study comparing the degree of adherence of silicone oil to various rigid and foldable intraocular lens (IOL) designs and to the human lens capsule.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Seven IOL styles comprising various biomaterials were studied: fluorine-treated (Fluorlens), heparin-surface-modified (HSM), hydrogel, Memory-Lens, Poly(methyl methacrylate) (PMMA), soft acrylic, and silicone lenses; the human crystalline lens was also studied. Each lens was immersed in silicone oil for 12 hours, than photographed, studied by scanning electron microscopy (except the crystalline lens), and subjected to computer-generated image analysis to determine the silicone oil coverage.

RESULTS

Silicone oil coverage of dry silicone lenses was 100% and of lenses immersed in normal saline, 82.5%. The least coverage was on the heparin-surface-modified lens (mean score 9.4%). Coverage of the other four lenses ranged from approximately 15.1% to 33.7%. Mean coverage of the human lens capsule was 10.9%.

CONCLUSION

Although a silicone IOL shows maximal adherence to silicone oil, other lens biomaterials are not immune to this complication. Silicone oil coverage was related to the dispersive energy component of the surface charge of the IOL biomaterial. Low dispersive energy materials had less silicone oil coverage, while those with higher dispersive energy had more oil coverage.

Use of 5-aminolevulinic acid esters to improve photodynamic therapy on cells in culture

Human tumor cells of the lines WiDr (adenocarcinoma of the rectosigmoid colon), NHIK 3025 (carcinoma of the cervix), and V79 Chinese hamster fibroblasts were treated with 5-aminolevulinic acid (ALA) and ALA esterified to C1-C3 and C6-C8 chained aliphatic alcohols (ALA-esters). In the human cell lines, esterification of ALA with the long-chain (C6-C8) alcohols was found to reduce 30-150-fold the amount of ALA needed to reach the same level of protoporphyrin IX (PpIX) accumulation as with non-esterified ALA. The long-chained ALA-esters were less efficient in stimulating PpIX formation in V79 cells, i.e., the same amount of PpIX was formed by a 1-2.6-fold lower concentration of long-chained ALA-esters than with ALA. Short-chained ALA-esters (C1-C3) induced 5 to 10 times lower PpIX accumulation than ALA in all of the cell lines. High-performance liquid chromatography and fluorescence microscopic studies indicated that esterification of ALA has neither impact on the fluorescing porphyrin species formed nor impact on their intracellular localization. The PpIX formed from ALA-esters and ALA was found to be equally efficient in sensitizing cells to photoinactivation. The present results indicate that esterified ALAs are new and promising drugs for use in photochemotherapy of cancer.

Effect of surface photorefractive keratectomy and laser in situ keratomileusis on the corneal endothelium

PURPOSE

To investigate endothelial cell loss in pairs of fresh human autopsy globes following high-diopter myopic photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK).

SETTING

Center for Research on Ocular Therapeutics and Biodevices and Magill Laser Center for Vision Correction, Storm Eye Institute, Charleston, South Carolina, USA.

METHODS

In the first part of the study, 12 globes had either -10 diopters (D) multizone surface PRK or -10 D single-zone LASIK. In the second part, three groups of 5 globes each had -15 D, -20 D, or -25 D multizone-blend LASIK procedures. Fellow globes in both groups were used as untreated controls. Corneoscleral buttons were excised from all globes. Following 7 days in corneal organ culture, the endothelial surface was stained with two vital dyes: calcein-AM and ethidium homodimer. Fluorescence microscopy was used to obtain endothelial cell counts.

RESULTS

The mean dead cells per square millimeter (cells/mm2) were 0.94 in the -10 D PRK treated corneas compared with 0.91 in the fellow untreated eyes (P = 0.06(. The mean dead cells/mm2 in the -10 D single-zone LASIK-treated corneas and in the fellow untreated eyes were 0.61 (P = 0.88). The mean dead cells/mm2 in the -15 D, -20 D, and -25 D multizone-blend LASIK-treated corneas were 3.08, 2.33, and 5.55, respectively, compared with 3.49, 1.92, and 5.01 in the fellow untreated eyes (P = 0.276, P = 0.339, and P = 0.427, respectively). Dead cell counts for treated and control paired corneas were highly correlated in all treatment groups.

CONCLUSIONS

No significant endothelial cell loss occurred after -10 D PRK or LASIK corrections up to -25 D. Although this study has limitations that prevent direct extrapolation to the clinical situation, it does afford a comparable clinical correlate for endothelial cell toxicity following a typical excimer laser ablations.

[Molfig, a software for displaying the structure and vibration of molecule]

A Molfig software has been developed for displaying the structure and vibrational mode of molecule in our lab. Various functions and a friendly interface are equipped in the software. The testing results showed that the software may enhance our understanding of the relationship between the vibrational behavior and the structure of molecules.

[Curvefit, an overlapping bands resolving software for IR spectra]

A Curvefit software has been developed for resolving the overlapping band of the vibartional spectra in our lab . Various functions and a friendly interface are equipped in the software. The testing results showed that both the speed of the calculation and the reliability of the final results are satisfactory.

Pharmacokinetic studies on 5-aminolevulinic acid-induced protoporphyrin IX accumulation in tumours and normal tissues

Laser-induced fluorescence (LIF) for in vivo point monitoring and fluorescence microscopy incorporating a CCD camera were used to study the fluorescence distribution of 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) in tumours. Fluorescence in a chemically-induced adenocarcinoma in the liver of rats and in an aggressive basal cell carcinoma in a patient were studied after intravenous injection of ALA at a dose of 30 mg/kg body weight. The LIF technique demonstrated slightly more ALA-induced PpIX fluorescence in the tumour than in the surrounding normal liver and abdominal muscle of rats. The visible parts of the human basal cell carcinoma exhibited strong ALA-induced fluorescence, while this fluorescence was much weaker in the necrotic areas of the tumour and in the surrounding normal skin.

Characterization of the protein product encoded by a splicing variant of the Marek's disease virus Eco-Q gene (Meq)

In the present study, we report the characterization of a 212-amino-acid polypeptide encoded by a splicing variant of the Marek's disease virus Eco-Q gene (Meq). This protein, referred to as Meq-sp, contains the N-terminal 100 amino acids of Meq, which include part of Meq's DNA binding/dimerization domain, but lacks the transactivation domain of Meq. Thus, Meq-sp was examined for its ability to bind to DNA and act as a transactivator. Results indicated that while Meq and Meq-sp could both bind to the AP-1 binding site, the 110 C-terminal amino acid residues of Meq-sp lacked the ability to function as a transactivator when fused to the GAL4 (1-147) DNA binding motif. To investigate whether Meq-sp can interact with Meq or with c-jun, protein-protein and protein-DNA interactions in vitro were examined. Results showed that Meq-sp can associate with both Meq and c-jun and bind to the AP-1 site with a higher affinity as a heterodimer with c-jun. These results suggest that Meq-sp could compete with Meq for heterodimer formation with c-jun and dimer binding to DNA and possibly act as a transdominant negative regulator of Meq activity in vivo.

Isolation and characterization of Marek's disease virus (MDV) cDNAs from a MDV-transformed lymphoblastoid cell line: identification of an open reading frame antisense to the MDV Eco-Q protein (Meq)

Two Marek's disease virus (MDV) cDNAs of 852 and 1168 bp, which map to the right end of the BamHI-I2 fragment of the MDV genome, were isolated from a cDNA library derived from the MDV transformed lymphoblastoid cell line MKT-1. These cDNAs hybridized to relatively abundant leftward mRNA transcripts in MKT-1 cells and cells lytically infected with MDV. The transcriptional initiation site for these transcripts was located in the adjacent BamHI-Q2 fragment, as determined by RNase protection and primer extension assays. A computer search for the presence of leftward open reading frames (ORFs) revealed two ORFs encoding 135- and 195-amino-acid polypeptides. A polyclonal antibody raised against a protein sequence in the N-terminus of the latter ORF detected a 23-kDa protein in the nuclear fraction of MDV-transformed lymphoblastoid cells. Furthermore, this ORF was antisense to part of the MDV Eco-Q protein (Meq) sequence.

Autoimmune lpr/lpr mice deficient in CD40 ligand: spontaneous Ig class switching with dichotomy of autoantibody responses

Fas-deficient MRL/Mp-lpr/lpr mice develop a syndrome that resembles human systemic lupus erythematosus, including production of IgG autoantibodies against small nuclear ribonucleoproteins (snRNPs), dsDNA, and self IgG (rheumatoid factor). To investigate the necessity for T-B cell contact in MRL autoimmunity, mice deficient in CD40 ligand (CD40L) were backcrossed onto this background, and Ab synthesis was assessed. In comparison to their CD40L-intact lpr/lpr counterparts, CD40L-deficient lpr/lpr mice had elevated levels of serum IgM and lower levels of IgG; however, a subset of animals had IgG2a, and to a lesser extent, IgG2b levels similar to those found in wild-type lpr/lpr mice. Levels of both isotypes in CD40L-deficient lpr/lpr mice were significantly greater than those found in nonautoimmune CD40L-deficient animals. IgG autoantibodies, including those directed against small nuclear ribonucleoproteins, also arose in CD40L-deficient lpr/lpr mice; however, they did not develop IgG rheumatoid factors or anti-dsDNA, and lacked histologic evidence of overt glomerulonephritis at age 3 mo, in contrast to CD40L-intact lpr/lpr animals. These results indicate that isotype switching occurs in lpr/lpr mice deficient in CD40L, and that production of IgG autoantibodies to ribonucleoproteins is at least partially preserved. They also suggest that different mechanisms may be responsible for eliciting autoantibody responses in lpr/lpr mice.

Autoimmune lpr/lpr mice deficient in CD40 ligand: spontaneous Ig class switching with dichotomy of autoantibody responses

Fas-deficient MRL/Mp-lpr/lpr mice develop a syndrome that resembles human systemic lupus erythematosus, including production of IgG autoantibodies against small nuclear ribonucleoproteins (snRNPs), dsDNA, and self IgG (rheumatoid factor). To investigate the necessity for T-B cell contact in MRL autoimmunity, mice deficient in CD40 ligand (CD40L) were backcrossed onto this background, and Ab synthesis was assessed. In comparison to their CD40L-intact lpr/lpr counterparts, CD40L-deficient lpr/lpr mice had elevated levels of serum IgM and lower levels of IgG; however, a subset of animals had IgG2a, and to a lesser extent, IgG2b levels similar to those found in wild-type lpr/lpr mice. Levels of both isotypes in CD40L-deficient lpr/lpr mice were significantly greater than those found in nonautoimmune CD40L-deficient animals. IgG autoantibodies, including those directed against small nuclear ribonucleoproteins, also arose in CD40L-deficient lpr/lpr mice; however, they did not develop IgG rheumatoid factors or anti-dsDNA, and lacked histologic evidence of overt glomerulonephritis at age 3 mo, in contrast to CD40L-intact lpr/lpr animals. These results indicate that isotype switching occurs in lpr/lpr mice deficient in CD40L, and that production of IgG autoantibodies to ribonucleoproteins is at least partially preserved. They also suggest that different mechanisms may be responsible for eliciting autoantibody responses in lpr/lpr mice.

Apoptosis and necrosis induced with light and 5-aminolaevulinic acid-derived protoporphyrin IX

The mode of cell death induced by photodynamic treatment (PDT) was studied in two cell lines cultured in monolayer, V79 Chinese hamster fibroblasts and WiDr human colon adenocarcinoma cells. The cells were incubated with 5-aminolaevulinic acid (5-ALA) as a precursor for the endogenously synthesised protoporphyrin IX, which was activated by light. Free DNA ends, owing to internucleosomal DNA cleavage in apoptotic cells, were stained specifically with a fluorescent dye in the terminal deoxynucleotidyl transferase (TdT) assay. The free DNA ends were measured by flow cytometry and the fractions of apoptotic cells determined. Total cell death was measured in a cell survival assay to determine the necrotic fraction after subtraction of the apoptotic fraction. V79 cells did undergo apoptosis while WiDr cells were killed only through necrosis. With time, the apoptotic fraction of V79 cells increased until a maximum was reached about 3-4 h after ALA-PDT treatment. For increasing ALA-PDT doses, a maximal apoptotic fraction 75-85% of the cells was measured at about 85% of total cell death. The flow cytometric assay of apoptosis was confirmed by the typical ladder of oligonucleosomal DNA fragments obtained from agarose gel electrophoresis, by fluorescence micrographs visualising the induced free DNA ends and by electron micrographs showing the typical morphology of apoptotic cells.

Influenza A virus RNA-dependent RNA polymerase cleaves influenza mRNA in vitro

We have investigated the endonuclease activity of the influenza A virus RNA polymerase in an in vitro assay with an artificial influenza-like mRNA containing a cap structure at its 5' terminus, followed by a 10 nt beta-globin mRNA sequence, and the 5' and 3' conserved termini of a truncated nucleoprotein (NP) cRNA influenza sequence. Results showed that partially purified virion ribonucleoprotein complexes (RNPs) and micrococcal nuclease treated RNPs cleaved the artificial influenza-like mRNA substrate specifically at positions near the 5' terminus to generate capped 14 and 15 nucleotide long RNA fragments which subsequently served as primers to initiate transcription. The endonuclease activity was completely blocked by addition of cap analog and competitively inhibited by added globin mRNA. Furthermore, an in vitro reconstituted influenza RNA transcription reaction containing a truncated NP vRNA as template, micrococcal nuclease treated RNPs and globin mRNA as primer, synthesized capped and uncapped full length (+) sense products. Enzyme kinetics showed that capped RNA was made earlier in the reaction; it reached a peak at 120 min and then declined. However, uncapped cRNA synthesis appeared later and remained as the dominant product later in the reaction. The nature of these products was confirmed by ribonuclease protection assays and by primer extension.

Germinal center formation, immunoglobulin class switching, and autoantibody production driven by "non alpha/beta" T cells

The production of class-switched antibodies, particularly immunoglobulin (Ig) G1 and IgE, occurs efficiently in T cell receptor (TCR) alpha-/- mice that are congenitally devoid of alpha/beta T cells. This finding runs counter to a wealth of data indicating that IgG1 and IgE synthesis are largely dependent on the collaboration between B and alpha/beta T cells. Furthermore, many of the antibodies synthesized in TCR alpha-/- mice are reactive to a similar spectrum of self-antigens as that targeted by autoantibodies characterizing human systemic lupus erythematosus (SLE). SLE, too, is most commonly regarded as an alpha/beta T cell-mediated condition. To distinguish whether the development of autoantibodies in TCR alpha-/- mice is due to an intrinsic de-regulation of B cells, or to a heretofore poorly characterized collaboration between B and "non-alpha/beta T" cells, the phenotype has been reconstituted by transfer of various populations of B and non-alpha/beta T cells including cloned gamma/delta T cells derived from TCR alpha-/- mice, to severe combined immunodeficient (SCID) mice. The results establish that the reproducible production of IgG1 (including autoantibodies) is a product of non-alpha/beta T cell help that can be provided by gamma/delta T cells. This type of B-T collaboration sustains the production of germinal centers, lymphoid follicles that ordinarily are anatomical signatures of alpha/beta T-B cell collaboration. Thus, non-alpha/beta T cell help may drive Ig synthesis and autoreactivity under various circumstances, especially in cases of alpha/beta T cell immunodeficiency.

Influenza A virus RNA-dependent RNA polymerase: analysis of RNA synthesis in vitro

Influenza A virus RNA-dependent RNA polymerase, purified from virion ribonucleoprotein particles and from which endogenous genomic RNA (vRNA) has been depleted by treatment with micrococcal nuclease, was used to study transcription initiation, elongation, and termination in vitro. Templates that contained either minus- or plus-sense influenza virus nucleoprotein minigenes with conserved 5' and 3' termini and the uridylate tract were constructed. The dinucleotide ApG and alfalfa mosaic virus RNA4 (AlMV4) were used as primers. ApG primed the synthesis of full-length positive-strand or cRNA products and shorter transcripts, depending upon the molar ratio between the nucleoprotein and the vRNA template. Sequence analysis of the ends of these transcripts demonstrated that the 5' termini of both transcripts and the 3' terminus of the full-length product were complementary to the 3' and 5' termini of the vRNA template, respectively, whereas the 3' terminus of the incomplete product corresponded to a sequence located 40 bases downstream from the 5' terminus of the template and was about 20 nucleotides downstream from the uridylate tract, which is the putative signal for polyadenylation. Binding of the cap structure of AlMV4 by the polymerase activated RNA synthesis by ligation-elongation of small genomic RNA fragments which were likely derived from a genome segment protected by the polymerase from micrococcal nuclease digestion. The sequence of these fragments mapped to a region 14 to 28 nucleotides upstream of the 3' terminus of the viral genome. Polymerase subunit involvement in transcription initiation with ApG or AlMV4 was characterized by studying the effect of purified polyclonal antisubunit immunoglobulins of the G class (IgGs) in transcription assays. These results showed that anti-PB2 IgG inhibited transcription initiation in both ApG- and AlMV4-primed reactions, whereas anti-PB1 antibodies also blocked transcription initiated with AlMV4. The differences observed in product size, product sequence, and differential inhibition by antisubunit IgGs are discussed. These observations would support the notion that the influenza virus RNA-dependent RNA polymerase undergoes a conformational change after the binding of the cap structure of host cell heterogeneous nuclear RNA by PB2, which then usually leads to endonucleolytic cleavage of the capped primer 13 nucleotides downstream from the cap.

Correlation of subcellular and intratumoral photosensitizer localization with ultrastructural features after photodynamic therapy

Photodynamic therapy (PDT) of cancer typically involves systemic administration of tumor-localizing photosensitizers followed 48-72 h later by exposure to light of appropriate wavelengths. Knowledge about the distribution of photosensitizers in tissues is still fragmentary. In particular, little is known as to the detailed localization patterns of photosensitizers in neoplastic and normal tissues as well as the relationship between such patterns and the actual targets for the photosensitizing effect. This review focuses on ultrastructural features seen in treated cells and tumors. An attempt is made to correlate these findings with the subcellular/intratumoral localization pattern of the photosensitizers in tumor cell lines in vitro and in tumor models in vivo. Several subcellular sites are main targets of PDT with different sulfonated aluminum phthalocyanines (AIPcSn) in the human tumor cell line LOX. Nuclei are not among the primary targets. Overall, the ultrastructural changes correlate well with the data about the subcellular localization patterns for each analogue of AIPcSn in the same cell line. Similar findings are also obtained for the family of sulfonated mesotetraphenylporphines (TPPSn) in the NHIK 3025 cell line. The mechanisms involved in the killing of tumors by PDT seem to be a complex interplay between direct and indirect (via vascular damage) effects on neoplastic cells according to the intratumoral localization pattern of the applied dye. Several factors can affect the localization pattern of a drug, such as its chemical character, the mode of drug delivery, the time interval between drug administration and light exposure, and tumor type. Furthermore, whether local immune reactions (such as macrophages) and apoptosis (programmed cell death) are involved in the destruction of neoplastic cells by PDT in vivo is still an enigma. A general model for PDT-induced tumor destruction is suggested.

Isolation and characterization of Marek's disease virus (MDV) cDNAs mapping to the BamHI-I2, BamHI-Q2, and BamHI-L fragments of the MDV genome from lymphoblastoid cells transformed and persistently infected with MDV

We have isolated and sequenced two cDNAs of sizes 2674 and 677 bp from a cDNA library derived from MKT-1, a lymphoblastoid cell line transformed and latently infected with Marek's disease virus (MDV) using probes corresponding to the right-hand end of the BamHI-I2 fragment of the MDV genome. The larger cDNA clone represents an abundant transcript, which extends from the right-hand end of BamHI-I2 to the adjacent BamHI-Q2 and BamHI-L fragments of the MDV genome and contains the Meq (MDV Eco-Q) open reading frame. The smaller cDNA clone represents a spliced transcript containing the putative DNA binding domain of Meq as well as sequences in the BamHI-L region. We prepared a polyclonal antibody against part of the protein sequence of Meq and detected a 44-kDa protein in MKT-1 cells and in cells lytically infected with MDV. In addition, riboprobes corresponding to sequences specific to each cDNA as well as shared sequences between cDNAs detected a number of transcripts in cells either lytically or latently infected with MDV. Our results indicate that the Meq transcriptional unit extends to the BamHI-L fragment and that the transcripts mapping to the right-hand end of the BamHI-I2 and adjacent BamHI-Q2 and BamHI-L fragments are not preferentially expressed during latency.

Distribution of 5-aminolevulinic acid-induced porphyrins in noduloulcerative basal cell carcinoma

Microscopic fluorescence photometry incorporating a light-sensitive thermo-electrically cooled charge-coupled device (CCD) camera was employed to investigate the fluorescence distribution of 5-aminolevulinic acid (ALA)-induced porphyrins in 22 patients with a total number of 52 noduloulcerative basal cell carcinomas (BCC) after topical ALA application with or without dimethylsulfoxide (DMSO)/ethylenediaminetetraacetic acid (EDTA) or after intravenous administration of ALA. Both localization patterns and amounts of ALA-induced porphyrins in the BCC were studied. The ALA-induced porphyrins were localized only in the superficial layers of the noduloulcerative BCC lesions after topical application of 20% ALA alone for 3 h. However, both the penetration of ALA into deep lesions and the production of the ALA-induced porphyrin fluorescence were increased after topical administration of 20% ALA and 20% DMSO/4% EDTA for 3 h. Prior treatment with 99% DMSO for 15 min further enhanced the ALA penetration into the BCC lesions after topical application of the ALA/DMSO/EDTA mixture and produced more ALA-induced porphyrins by a factor of about three compared with those treated with ALA alone. The penetration of ALA into the deep BCC lesions could also be increased by prolonging the time of topical application of 20% ALA/4% EDTA to 29-48 h (without DMSO). Intravenous injection of ALA led to a more homogeneous distribution of the ALA-derived porphyrins in the whole noduloulcerative BCC lesions.

The rise and prospects of medical aesthetics

Since the 1980s, Chinese scholars have been trying to expound and synthetise elementary aesthetical ideas which occur in medicine, in order to treat this area of study as a defined branch of medicine--'medical aesthetics'. It is in this context that the points discussed in this paper arise. We set forth in detail the ideas, objectives and methods adopted within the framework of medical aesthetics and its applied branch--medical cosmetology and expound the relations between them. We think the task of medical aesthetics is to study the human body in its entirety, concentrating on both internal and external beauty and put the findings into practice, whereas the task of medical cosmetology is to study and assess only the external beauty of the human body and to take action on that basis. Medical cosmetology is the enforcement of medical aesthetics, practised in order to give positive results connected with physical beauty, and is therefore easily understood by the layman. It is known that the development of medical cosmetology represents an important breakthrough in the development of medical aesthetics. We think that beauty should not be measured mechanically, always following the same pattern, but that it should be considered individually with everyone's own particular characteristics. The quality of physical attractiveness should be assessed jointly by the doctor and his patient or client, not solely by either of these individuals nor even by a group of doctors.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of distribution of sulphonated aluminium phthalocyanines with their photodynamic effect in tumour and skin of mice bearing CaD2 mammary carcinoma

A chemical extraction assay and fluorescence microscopy incorporating a light-sensitive thermoelectrically cooled charge-coupled device (CCD) camera was used to study the kinetics of uptake, retention and localisation of disulphonated aluminium phthalocyanine (A1PcS2) and tetrasulphonated aluminium phthalocyanine (A1PcS4) at different time intervals after an i.p. injection at a dose of 10 mg kg-1 body weight (b.w.) in tumour and surrounding normal skin and muscle of female C3D2/F1 mice bearing CaD2 mammary carcinoma. Moreover, the photodynamic effect on the tumour and normal skin using sulphonated aluminium phthalocyanines (A1PcS1, A1PcS2, A1pcS4) and Photofrin was compared with respect to dye, dye dose and time interval between dye administration and light exposure. The maximal concentrations of A1PcS2 in the tumour tissue were reached 2-24 h after injection of the dye, while the amounts of A1PcS4 peaked 1-2 h after the dye administration. A1PcS2 was simultaneously localised in the interstitium and in the neoplastic cells of the tumour, whereas A1PcS4 appeared to localise only in the stroma of the tumour. The photodynamic efficiency (light was applied 24 h after dye injection at a dose of 10 mg kg-1 b.w.) of the tumours was found to decrease in the following order: A1PcS2 > A1PcS4 > Photofrin > A1PcS1. Furthermore, photodynamic efficacy was strongly dependent upon dye doses and time intervals between dye administration and light exposure: the higher the dose, the higher the photodynamic efficiency. The most efficient photodynamic therapy (PDT) of the tumour was reached (day 20 tumour-free) when light exposure took place 2 h after injection of A1PcS2 (10 mg kg-1). A dual intratumoral localisation pattern of the dye, as found for A1PcS2, seems desirable to obtain a high photodynamic efficiency. The kinetic patterns of uptake, retention and localisation of A1PcS2 and A1PcS4 are roughly correlated with their photodynamic effect on the tumour and normal skin.

Uptake, localization, and photodynamic effect of meso-tetra(hydroxyphenyl)porphine and its corresponding chlorin in normal and tumor tissues of mice bearing mammary carcinoma

By using a chemical extraction assay and confocal laser scanning fluorescence microscopy, the kinetic patterns of uptake, elimination, and localization of meso-tetra(hydroxyphenyl)porphine (m-THPP) and its corresponding chlorin (m-THPC) in tumors and various normal tissues of female C3D2/F1 mice bearing CaD2 mammary carcinoma were studied after an i.p. injection of either 5 mg/kg body weight of m-THPP or 1 mg/kg body weight of m-THPC. Moreover, the histological and ultrastructural alterations of the tumors were evaluated after photodynamic therapy (PDT) with m-THPP or m-THPC. The PDT efficacy with m-THPP and m-THPC was also compared. Both m-THPP and m-THPC had a similar kinetic pattern of distribution in the tumors and most normal tissues examined. The concentrations of the dyes in the tissues peaked at 24-48 h after injection. The peak values of the uptake of m-THPP by the tissues were found to decrease in the following order: spleen > urinary tract > kidney > liver > lung > tumor > heart > skin > muscle > brain. However, higher concentrations of m-THPC were taken up by the tumors than by most of the normal tissues studied except for the liver, urinary tract, and skin. m-THPP was mainly localized in the stroma of the tumors, whereas m-THPC was distributed in both vascular interstitium and neoplastic cells of the tumors. Morphological studies showed that PDT with m-THPP resulted in destructive changes in the microvasculature of the tumors, whereas m-THPC-based PDT destroyed both vascular walls and tumor cells of the tumors. The m-THPP-PDT of the tumors was much less efficient than m-THPC-PDT of the tumors, although the dose of m-THPP used was five times higher than that of m-THPC. m-THPP and m-THPC have different efficiency of sensitizing tumors to photodestruction, although they are similar with respect to hydrophobicity. This is likely due to the differences in their intratumoral localization patterns and in their absorption spectra.

The haem b558 component of the cytochrome bd quinol oxidase complex from Escherichia coli has histidine-methionine axial ligation

The cytochrome bd ubiquinol oxidase from Escherichia coli is induced when the bacteria are cultured under microaerophilic or low-aeration conditions. This membrane-bound respiratory oxidase catalyses the two-electron oxidation of ubiquinol and the four-electron reduction of dioxygen to water. The oxidase contains three haem prosthetic groups: haem b558, haem b595 and haem d. Haem d is the oxygen binding site, and it is likely that haem d and b595 form a bimetallic site in the enzyme. Haem b558 has been previously characterized spectroscopically as being low spin and has been shown to be located within subunit I (CydA) of this two-subunit enzyme. It is likely that haem b558 is associated with the quinol oxidation site, which has also been shown to be within subunit I. In a previous effort to locate the specific amino acids axially ligated to haem b558, all six histidines within subunit I were altered by site-directed mutagenesis. Only one, histidine-186, was identified as a likely ligand to haem b558. Hence it was suggested that haem b558 could not have bis(histidine) ligation. In the current work, a combination of low-temperature near-infrared magnetic circular dichroism (NIR-MCD) and EPR spectroscopies have been employed to identify the nature of the haem b558 axial ligands. The NIR-MCD spectrum at cryogenic temperatures is dominated by the low-spin haem b558 component of the complex, and the low-energy band near 1800 nm is strong evidence for histidine-methionine ligation. It is concluded that haem b558 is ligated to histidine-186 plus one of the methionines located within subunit I of the oxidase.

Influenza A virus RNA polymerase subunit PB2 is the endonuclease which cleaves host cell mRNA and functions only as the trimeric enzyme

The influenza A virus RNA-dependent RNA polymerase catalyzes several reactions in transcription and replication of the genome RNA. The first step in viral mRNA synthesis is the endonucleolytic cleavage of host cell mRNAs containing a cap structure to generate capped primers that are 10-14 nucleotides long which are then used to prime transcription of virus-specific mRNAs. To analyze the properties of the capped RNA-specific endonuclease associated with the influenza virus polymerase and the roles of each of the three subunits in transcription initiation, we established an in vitro assay to investigate this endonucleolytic cleavage reaction. This assay consists of an artificial RNA substrate containing a cap-0 structure at its 5' end and a partial alfalfa mosaic virus RNA 4 (AIMV RNA 4) sequence which had been shown to be cleaved by the influenza polymerase. Results showed that purified virion ribonucleoprotein complexes cleaved the RNA substrate specifically to generate a capped 14-nt RNA fragment for use as primer to initiate viral mRNA synthesis. Purified polyclonal anti-PB2 IgG inhibited the endonuclease activity, but anti-PB1 and anti-PA antibodies did not inhibit the cleavage. Partially purified trimeric polymerase expressed by recombinant baculovirus in insect cells cleaved the artificial substrate, but if one or two subunits were removed from the polymerase complex, the cleavage activity was totally lost. Our results suggest that viral PB2 protein is the endonuclease that cleaves host cell mRNA to produce the primer used to initiate transcription; however, association with the other two enzyme subunits seems to be required for this PB2 function.