Comparison of the S RNA segments among Japanese isolates and Taiwanese isolates of Watermelon silver mottle virus

The complete nucleotide sequences of the S RNA of two Japanese isolates of Watermelon silver mottle virus were determined. One was isolated from naturally infected watermelon and causes malformation on upper leaves of Tetragonia expansa. The other was isolated from melon and causes characteristic yellow necrotic lesions on upper leaves of T. expansa. The total nucleotide sequences of the S RNA of WS-O and WS-Y were 3553 nt and 3558 nt long, respectively. Both the nucleotide sequences and the deduced amino acid sequences of WS-O and WS-Y were quite similar even though the symptoms on T. expansa are quite different. They were also significantly similar to those of the Taiwanese isolates, Topso-W and Tospo-To. These results suggested that the Japanese isolates and the Taiwanese isolates of WSMoV were classified as one group not only serologically but also genetically. Within the S RNA sequences, the most variable region was the intergenic region between the N gene and the NSs gene. This was due to a 20 nt insertion between the Japanese isolates and the Taiwanese isolates.

In vitro and in vivo antibacterial activity and pharmacokinetics of SC-002 and its derivative, SC-004: new oral cephalosporins

SC-002 is a novel oral cephalosporin possessing a unique thiadiazolylethenyl moiety at the 3 position. In the present study, it was the most active against gram-positive bacteria among oral cephalosporins such as cefdinir (CFDN), cefpodoxime, cefditoren and cefaclor (CCL). It was equal to or 16 times more active than CFDN against standard and clinical strains. In particular, against clinical isolates of Morganella morganii and Haemophilus influenzae, SC-002 was 8-64 times more active than CFDN. The antibacterial activity of SC-002 against some beta-lactam-resistant strains was superior to that of CFDN. The in vivo antibacterial activity of SC-004, a pivaloyloxymethyl ester of SC-002, was 1.2-8 times more protective against systemic infections due to Streptococcus pneumoniae, Escherichia coli and Klebsiella pneumoniae than that of CFDN. The therapeutic effects of SC-004 on experimental respiratory tract infections caused by S. pneumoniae or H. influenzae were superior to those of CFDN and CCL. SC-004 showed higher and longer-lasting blood levels and higher urinary excretion in pharmacokinetics in mice.

Role of DNA ligase in the illegitimate recombination that generates lambdabio-transducing phages in Escherichia coli

We studied the role of DNA ligase in illegitimate recombination in Escherichia coli. A temperature-sensitive mutation in the lig gene reduced the frequency with which lambdabio-transducing phages were generated to 10-14% of that of wild type under UV irradiation. Reintroduction of the lig gene into this mutant restored the frequency of recombinant phage generation to that of wild type. Furthermore, overexpression of DNA ligase enhanced illegitimate recombination by 10-fold with or without UV irradiation. In addition, when DNA ligase was present in only limited amounts, UV-induced or spontaneous illegitimate recombination occurred exclusively at hotspot sites that have relatively long sequences of homology (9 or 13 bp). However, when DNA ligase was overexpressed, most of the illegitimate recombination took place at non-hotspot sites having only short sequences of homology (<4 bp). Thus, the level of ligase activity affects the frequency of illegitimate recombination, the length of sequence homology at the recombination sites, and the preference for recombination at hotspots, at least after UV irradiation. These observations support our hypothesis that the illegitimate recombination that generates lambdabio-transducing phages is mediated by the DNA break-and-join mechanism.

Condylar bony change, disk displacement, and signs and symptoms of TMJ disorders in orthognathic surgery patients

OBJECTIVE

We sought to investigate the relationship between condylar bony change and disk displacement with respect to the signs and symptoms of temporomandibular joint (TMJ) disorders in patients undergoing orthognathic surgery.

STUDY DESIGN

We performed a cross-sectional retrospective study of the pretreatment helical computed tomography scans of 129 orthognathic surgery patients.

RESULTS

Condylar bony change, unilaterally or bilaterally, was found in 35.7% of the subjects and 24.4% of the joints. Disk displacement, unilaterally or bilaterally, was seen in 41.4% of the subjects and 29.5% of the joints. The type of craniofacial deformity was significantly associated with condylar bony change and disk displacement. No association of clinical symptoms with respect to craniofacial deformity, condylar bony change, or disk displacement was found except in the case of TMJ sounds.

CONCLUSION

The results suggested that craniofacial deformity might be related to TMJ disorders, but the only clinical symptom associated with types of craniofacial deformity was TMJ sounds.

Population pharmacokinetic analysis of cisplatin and its metabolites in cancer patients: possible misinterpretation of covariates for pharmacokinetic parameters calculated from the concentrations of unchanged cisplatin, ultrafiltered platinum and total platinum

BACKGROUND

Usually, total and filtered platinum concentrations in plasma are monitored after cisplatin administration. However, these concentrations represent a mixture of unchanged cisplatin and metabolites. In this work, we studied population pharmacokinetic analysis based on these platinum concentrations.

METHODS

Twenty-seven patients (23 males, four females) were administered cisplatin (60-100 mg/m2) with intravenous constant infusion for 90 min. Blood samples were taken at about three points per patient. The concentrations of cisplatin and platinum in the plasma were determined by high-performance liquid chromatography and atomic absorption spectrometry, respectively. Population pharmacokinetic analysis was performed using the program NONMEM (Version V) with the one- or two-compartment model with zero-order infusion.

RESULTS

The clearance and volume of distribution for all platinum species studied were significantly related to the body surface area of the patients. Only the clearance of filtered platinum was significantly related to urinary N-acetyl-beta-D-glucosaminidase and the other covariates were not related to these pharmacokinetic parameters with respect to unchanged cisplatin and total platinum concentrations.

CONCLUSION

The dosage regimen based on the filtered platinum concentration which is usually monitored may result in possible misinterpretation because the detected covariate is different between unchanged cisplatin and filtered platinum.

[The clinical application and modification of the Quad Helix appliance]

OBJECTIVE

The aims of this study are to investigate the working mechanism, the characteristics, the clinical application and the suggested modification of the Quad Helix appliance.

METHODS

A 7-year-old, female patient with Pierre-Rokin syndrome, who was preformed with palatorrhaphy at 21-month-old treated by using a Quad Helix appliance for one year.

RESULTS

After one-year treatment, the wide between the maxillary first molars increased 9.65 mm, and the wide between maxillary canines increased 5.20 mm. The wide between the mandibular first molars also increased 3.60 mm, however the wide between mandibular canines decreased 5.20 mm.

CONCLUSION

The Quad-helix appears to be a successful Orthodontic appliance to expand the narrow maxillary or mandibular arches.

BMP-2 induction and TGF-beta 1 modulation of rat periosteal cell chondrogenesis

Periosteum contains osteochondral progenitor cells that can differentiate into osteoblasts and chondrocytes during normal bone growth and fracture healing. TGF-beta 1 and BMP-2 have been implicated in the regulation of the chondrogenic differentiation of these cells, but their roles are not fully defined. This study was undertaken to investigate the chondrogenic effects of TGF-beta 1 and BMP-2 on rat periosteum-derived cells during in vitro chondrogenesis in a three-dimensional aggregate culture. RT-PCR analyses for gene expression of cartilage-specific matrix proteins revealed that treatment with BMP-2 alone and combined treatment with TGF-beta 1 and BMP-2 induced time-dependent mRNA expression of aggrecan core protein and type II collagen. At later times in culture, the aggregates treated with BMP-2 exhibited expression of type X collagen and osteocalcin mRNA, which are markers of chondrocyte hypertrophy. Aggregates incubated with both TGF-beta 1 and BMP-2 showed no such expression. Treatment with TGF-beta 1 alone did not lead to the expression of type II or X collagen mRNA, indicating that this factor itself did not independently induce chondrogenesis in rat periosteal cells. These data were consistent with histological and immunohistochemical results. After 14 days in culture, BMP-2-treated aggregates consisted of many hypertrophic chondrocytes within a metachromatic matrix, which was immunoreactive with anti-type II and type X collagen antibodies. In contrast, at 14 days, TGF-beta 1 + BMP-2-treated aggregates did not contain any morphologically identifiable hypertrophic chondrocytes and their abundant extracellular matrix was not immunoreactive to the anti-type X collagen antibody. Expression of BMPR-IA, TGF-beta RI, and TGF-beta RII receptors was detected at all times in each culture condition, indicating that the distinct responses of aggregates to BMP-2, TGF-beta 1 and TGF-beta 1 + BMP-2 were not due to overt differences in receptor expression. Collectively, our results suggest that BMP-2 induces neochondrogenesis of rat periosteum-derived cells, and that TGF-beta 1 modulates the terminal differentiation in BMP-2 induced chondrogenesis.

A case of anterior open bite developing during adolescence

Imaging studies have reported on the relationship between temporomandibular joint (TMJ) degeneration and facial deformity. These studies have suggested that mandibular growth is affected by TMJ degeneration, resulting in altered skeletal structure as mandibular retrusion. However, there are very few longitudinal case reports on TMJ osteoarthrosis (OA). Progressive open bite occurred in an adolescent patient with TMJ OA. Cephalometric analysis showed a downward and backward rotated mandible, and a labial inclination of the upper incisor. Magnetic resonance imaging showed internal derangement without reduction and erosion in the right and the left condyles. Although the cause of open bite is unclear in this case, tongue thrusting, and internal derangements in the temporomandibular joint were suspected as causes of the open bite.

Multilayered amniotic membrane transplantation for severe ulceration of the cornea and sclera

PURPOSE

To examine the efficacy of amniotic membrane transplantation in the treatment of deep corneal and scleral ulcers.

PATIENTS

A total of 11 patients were recruited for this study: four patients (four eyes) with corneal perforation, five patients (five eyes) with a deep corneal ulcer and descemetocele, and two patients (two eyes) with a scleral ulcer.

METHODS

Ulcers were treated by amniotic membrane transplantation. Separate amniotic membranes were transplanted as material to fill the stromal layer (amniotic membrane filling), as a basement membrane (amniotic membrane graft), and as a wound cover (amniotic membrane patch). After surgery, all cases were treated with artificial tears, autologous serum drops, antibiotic eyedrops, topical corticosteroids, and sodium hyaluronate eyedrops.

RESULTS

Eight eyes (72.7%) healed with epithelialization in 16.5 +/- 8.0 days (range, 7 to 29 days), with five and three eyes showing corneal epithelialization and conjunctival epithelialization, respectively. A persistent epithelial defect was noted in one eye with corneal ulcer after limbal allograft transplantation for a chemical burn and in two eyes with corneal ulcers as a complication of rheumatoid arthritis.

CONCLUSION

Multilayered amniotic membrane transplantation may be effective for the treatment of deep ulceration of the cornea and sclera. In some eyes with total corneal limbal dysfunction or autoimmune disorders, amniotic membrane transplantation alone is not effective.

X-ray induced reduction of rare earth ion doped in Na2O-Al2O3-B2O3 glasses

5Na2O-10Al2O3-85B2O3 glasses doped with 0.05 mol% Sm2O3 or 0.05 mol% Eu2O3 turn to orange after irradiation by focussed femtosecond pulsed laser or x-ray irradiation. To know the mechanism of photo-induced coloring, the glasses were studied by Sm or Eu L(III) XANES before and after x-ray or UV irradiation. XANES in both edges showed that a part of trivalent ion converted to divalent ion upon the irradiation of x-ray. These facts reveal that photoreduction of rare earth ion is the mechanism of photo-induced coloring. However no photoreduction upon UV irradiation occurred in both glasses.

Optimal atrioventricular delay setting determined by evoked QT interval in patients with implanted stimulus-T-driven DDDR pacemakers

Cardiac function is improved by optimizing the atrioventricular (AV) delay. An automatic optimizing function of AV delay may be necessary to achieve the most favourable haemodynamic state in paced patients. The QT interval may change when cardiac function is improved by optimizing the AV delay. The QT or stimulus-T interval is used as a sensor for rate-responsive pacemakers. Evoked (e) QT interval is measured as the time duration from the ventricular pace pulse (stimulus) and the T-sense point that is the steepest point of the intracardiac T wave (stimulus-T interval). The relationship between AV delay, eQT interval and cardiac function was studied in 10 patients (73 +/- 10 (SD) years old) with an implanted stimulus-T-driven DDDR pacemaker. Cardiac output (CO) and pulmonary capillary wedge pressure (PCWP) were measured by Swan-Ganz catheter. The AV delay was prolonged stepwise by 30 ms. Electrocardiogram event markers which indicated ventricular spike and sensed T wave were recorded, and the interval between two event markers was measured as eQT interval. When AV delay was changed from 240 ms to the AV delay at which CO was maximal (172 +/- 33 ms), eQT interval prolonged from 346 +/- 60 to 353 +/- 62 ms (P < 0.01). There was a significant positive correlation between the optimal AV delay at which CO was maximal (172 +/- 33 ms) and the optimal AV delay which was predicted from the maximum eQT interval (179 +/- 37 ms, r = 0.92, P < 0.001). When AV delay was changed from 240 ms to the predicted optimal AV delay, CO increased from 4.2 +/- 0.7 to 4.5 +/- 0.81.min-1 (P < 0.001) and PCWP was decreased from 7.1 +/- 4.0 to 5.7 +/- 3.1 mmHg (P < 0.05). In conclusion, the optimal AV delay can be predicted from the eQT interval which is sensed by an implanted pacemaker. Automatic setting of the optimal AV delay may be achieved by the QT sensor of an implanted pacemaker.

Role of stromal cells in osteoclast differentiation in bone marrow

Bone marrow stromal cells have been considered to play an important role in osteoclast differentiation. However, the interaction of these cells in vivo has not been clearly demonstrated. To clarify this, we examined the distribution of alkaline phosphatase (ALPase) and tartrate-resistant acid phosphatase (TRAPase) activities as markers of osteoblastic and osteoclastic cells, respectively. Rat tibiae were fixed and embedded in Technovit 8100 or paraffin. ALPase and TRAPase activities were detected simultaneously on a plastic section by the azo-dye method. ALPase activity was detected on the plasma membranes of osteoblasts and some bone marrow fibroblastic stromal cells. These ALPase-positive cells were connected to each other by cytoplasmic processes, forming a cellular network in bone marrow. The ALPase activity of fibroblastic stromal cells tended to be stronger in those cells close to the bone surface than in the cells in the center of bone marrow. Reticular fibers in bone marrow were found to form a network. The ALPase-positive fibroblastic stromal cells may be reticular cells, because the localization of those cells was in accord with the localization of reticular fibers. The TRAPase-positive mononuclear cells and osteoclasts were mostly observed to be associated with the intensely ALPase-positive fibroblastic stromal cells. Immunoreactivity of osteoclast differentiation factor (ODF) was found in the fibroblastic stromal cells. These findings suggest that the network of ALPase-positive fibroblastic stromal cells in bone marrow serves as a guide for the migration of osteoclast precursor cells toward the bone surface, and may control the differentiation and activity of osteoclasts.

Acute effects of E-3174, a human active metabolite of losartan, on the cardiovascular system in tachycardia-induced canine heart failure

The aim of this study was to evaluate the acute effects of E-3174, a human active metabolite of the AT1 receptor antagonist, losartan, on hemodynamic functions in dogs with severe heart failure (HF). In dogs, insignificant plasma levels of E-3174 are present following administration of losartan, and therefore, the effects of these two drugs can be studied independently in the dog. HF was established by rapid pacing of the right ventricle (250-270 beats/min) for 4 weeks. We examined changes in cardiovascular functions after acute intravenous administration of losartan (1 mg/kg) and E-3174 (0.3 and 1 mg/kg), as well as an ACE inhibitor, enalapril (0.3 and 1 mg/kg), under condition of HF. The HF before treatment was characterized by increases in pre- and after-load of the left ventricle (LV), consequent low cardiac output, and LV dilatation. E-3174 at 0.3 and 1 mg/kg reduced pulmonary artery pressure (-13+/-6% and -22+/-3% from baseline, respectively, p<0.05), pulmonary capillary wedge pressure (-18+/-4% and -36+/-10%, p<0.05) and mean arterial pressure (-24+/-2% and -36+/-7%, p<0.05), increased stroke volume (SV: +12+/-7% p>0.05; +36 +/-19%, p<0.05), and reduced peripheral resistance (-23+/-5% and -41+/-9%, p<0.05), but had no effect on the first derivative of left ventricular pressure (dP/dt/P) or the time constant for relaxation. Effects of losartan at 1 mg/kg were similar to those of 0.3 mg/kg of E-3174. Enalapril at 1 mg/kg caused changes comparable to those seen after E-3174 administration (1 mg/kg), except that the increase in SV (+16+/-8%, p<0.05) with enalapril was not as great as that with E-3174. Both losartan at 1 mg/kg and E-3174 at 0.3 and 1 mg/kg increased fractional shortening to a similar extent (FS: +52+/-12%, +47+/-8% and +56+/-8%), while enalapril at 0.3 and 1 mg/kg had no significant effects on FS. Reflex elevation of plasma renin activity induced by 1 mg/kg of E-3174 was similar to that caused by 1 mg/kg of enalapril, suggesting that the two drugs achieved similar inhibition of the endogenous renin angiotensin system. Our study demonstrated that acute blockade of the AT1 receptor with E-3174 reduced elevated pre- and after-load and consequently increased stroke volume in a canine HF model. With the exception of changes in stroke volume, these effects of E-3174 were comparable to those produced by enalapril, and were 3 times stronger than those by losartan.

Host cell-derived sphingolipids are required for the intracellular growth of Chlamydia trachomatis

Chlamydia trachomatis, an important cause of human disease, is an obligate intracellular bacterial pathogen that relies on the eukaryotic host cell for its replication. Recent reports have revealed that the C. trachomatis vacuole receives host-derived sphingolipids by fusing with trans-Golgi network (TGN)derived secretory vesicles. Here, it is shown that these lipids are required for the growth of the bacteria. C. trachomatis was unable to replicate at 39 degrees C in the Chinese hamster ovary (CHO)-derived cell line SPB-1, a cell line incapable of synthesizing sphingolipids at this temperature because of a temperature-sensitive mutation in the serine palmitoyltransferase (SPT) gene. Complementation with the wild-type SPT gene or addition of exogenous cell-permeable sphingolipid precursors to the mutant cells restored their ability to support chlamydial replication. L-cycloserine (L-CS) and fumonisin B1 (FB1), inhibitors of sphingolipid biosynthesis, decreased the proliferation of the bacteria in eukaryotic cells at concentrations that also decreased host cell sphingolipid synthesis. In the case of FB1, the vacuoles appeared aberrant; the addition of sphingolipid precursors was able to reverse the altered morphology of the FB1-treated vacuoles. Collectively, these data strongly suggest that the growth and replication of chlamydiae is dependent on synthesis of sphingolipids by the eukaryotic host cell and may contribute to this organism's obligate intracellular parasitism.

Effect of buthionine sulphoximine, glutathione and methimazole on the renal disposition of cisplatin and on cisplatin-induced nephrotoxicity in rats: pharmacokinetic-toxicodynamic analysis

The aim of this study was to classify the protective mechanisms of DL-buthionine-(S,-R)-sulphoximine, glutathione and methimazole on cisplatin-induced nephrotoxicity in rats. An Emax model was used to study the effect of these compounds on the pharmacokinetics of cisplatin, especially renal handling and intra-renal biotransformation. Cisplatin (5 mg kg(-1)) was administered as an intravenous bolus to rats treated with either 0.9% NaCl (control), buthionine sulphoximine, glutathione or methimazole. The blood urea nitrogen level was monitored to estimate cisplatin-induced nephrotoxicity. To estimate renal handling of cisplatin, cisplatin was infused intravenously to rats treated with 0.9% NaCl, buthionine sulphoximine, glutathione or methimazole. The concentrations of unchanged cisplatin in plasma, urine and kidney were determined by a post-column derivatization HPLC method. The relationship between the pharmacokinetics and toxicodynamics of cisplatin was analysed using a sigmoid Emax model. All compounds studied ameliorated significantly the nephrotoxicity of cisplatin. The renal accumulation of cisplatin was reduced significantly by pretreatment with buthionine sulphoximine but not by either glutathione or methimazole. Although glutathione treatment did not affect the renal accumulation of cisplatin, it significantly decreased the binding of cisplatin to the intrarenal organelle and the decreased binding was well correlated to the decrease of the blood urea nitrogen level. In summary, pharmacokinetic-toxicodynamic analysis will be useful for classifying the protective mechanism of cisplatin-induced nephrotoxicity.

Reduction of sphingomyelin level without accumulation of ceramide in Chinese hamster ovary cells affects detergent-resistant membrane domains and enhances cellular cholesterol efflux to methyl-beta -cyclodextrin

We examined the effects of reduction of sphingomyelin level on cholesterol behavior in cells using 2 types of Chinese hamster ovary cell mutants deficient in sphingomyelin synthesis: LY-A strain defective in intracellular trafficking of ceramide for sphingomyelin synthesis, and LY-B strain defective in the enzyme catalyzing the initial step of sphingolipid biosynthesis. Although the sphingomyelin content in LY-A and LY-B cells was approximately 40 and approximately 15%, respectively, of the wild-type level without accumulation of ceramide, these mutant cells were almost identical in cholesterol content and also in plasma membrane cholesterol level to the wild-type cells. However, density gradient fractionation analysis of Triton X-100-treated lysates of cells prelabeled with [(3)H]cholesterol showed that the [(3)H]cholesterol level in the low-density floating fraction was lower in sphingomyelin-deficient cells than in wild-type cells. When cells were exposed to methyl-beta-cyclodextrin, cholesterol was more efficiently fluxed from sphingomyelin-deficient cells than wild-type cells. These results suggest that the steady state level of cholesterol at the plasma membrane is little affected by the sphingomyelin levels in Chinese hamster ovary cells, but that sphingomyelin levels play an important role in the retention of cholesterol in the plasma membrane against efflux to extracellular cholesterol-acceptors, due to interaction between sphingomyelin and cholesterol in detergent-resistant membrane domains.

Pharmacokinetics and toxicodynamics of cisplatin and its metabolites in rats: relationship between renal handling and nephrotoxicity of cisplatin

The renal handling of cisplatin and its metabolites and the relationship between the pharmacokinetics of these platinum species in the kidney and nephrotoxicity in rats were studied by carrying out pharmacokinetic-pharmacodynamic analysis. Rats received cisplatin intravenously as a bolus (2-10 mgkg(-1)) or by constant infusion (55 and 140 microg min(-1) kg(-1)). After intravenous administration of each platinum species, the platinum concentrations of unchanged cisplatin and its mobile and fixed metabolites were determined separately. Nephrotoxicity was estimated by measuring the blood urea nitrogen (BUN) levels and the sigmoid Emax model was used to determine the relationship between pharmacokinetic parameters and BUN levels 5 days after cisplatin administration. Cisplatin and its mobile metabolites in plasma distributed more rapidly and extensively into the kidney (mean apparent kidney-to-plasma concentration ratios were 2.69 and 7.12 mL (g tissue)(-1), respectively) than into the liver (less than 1 mL (g tissue)(-1)). Concomitant administration of mobile metabolites did not significantly alter the disposition of cisplatin. Nephrotoxicity, estimated by measuring BUN levels, appeared to be related to the plasma concentration of intact cisplatin, not total platinum, because mobile metabolites formed from cisplatin showed little nephrotoxicity. The sigmoid Emax model showed the maximum BUN level reached after cisplatin administration was related to the area under the renal cisplatin concentration-time curve (AUCk).

Changes in ocular surface caused by antiglaucomatous eyedrops: prospective, randomised study for the comparison of 0.5% timolol v 0. 12% unoprostone

AIM

To study changes induced in ocular surface epithelia and the tear film by antiglaucomatous eyedrops. A beta blocker (0.5% timolol) and a novel prostaglandin F(2alpha) metabolite related drug (0.12% unoprostone) were examined in a prospective, randomised fashion.

METHODS

40 patients were randomly assigned to use either 0. 5% timolol (timolol group) or 0.12% unoprostone eyedrops (unoprostone group) twice a day for 24 weeks. In addition to routine ocular examinations, corneal epithelial integrity (vital staining tests, tear film break up time (BUT), anterior fluorometry, specular microscopy) and tear function (Schirmer's test, cotton thread test, tear clearance test (TCT)) were examined before and after the treatment.

RESULTS

Both eyedrops caused significant reduction in intraocular pressure from the baseline levels. No significant changes were noted in corneal integrity in both groups, except a decrease in BUT at 20 weeks in the timolol group. The timolol group demonstrated significant decreases in Schirmer's test, tear clearance test, and tear function index (Schirmer's test value multiplied by clearance test); however, no such changes were noted in the unoprostone group.

CONCLUSION

While unoprostone eyedrops caused no adverse effects on the corneal epithelial integrity and tear function, timolol caused significant impairments in tear production and turnover.

Reconstitution of ATP- and cytosol-dependent transport of de novo synthesized ceramide to the site of sphingomyelin synthesis in semi-intact cells

Transport of ceramide synthesized at the endoplasmic reticulum to the Golgi compartment, where sphingomyelin (SM) synthase exists, was reconstituted within semi-intact Chinese hamster ovary cells. When [(3)H]ceramide that had been produced from [(3)H]sphingosine at 15 degrees C in perforated cells was chased at 37 degrees C, [(3)H]ceramide-to-[(3)H]SM conversion occurred in a cytosol-dependent manner. In various aspects (i.e. kinetics, ATP dependence, and temperature dependence), [(3)H]ceramide-to-[(3)H]SM conversion in perforated cells was consistent with that in intact cells. The cytosol from LY-A strain, a Chinese hamster ovary cell mutant defective in endoplasmic reticulum-to-Golgi transport of ceramide, did not support [(3)H]ceramide-to-[(3)H]SM conversion in perforated wild-type cells, whereas the wild-type cytosol rescued the conversion in perforated LY-A cells. Brefeldin A-treated cells, in which the endoplasmic reticulum and the Golgi apparatus were merged, no longer required cytosol for conversion of [(3)H]ceramide to [(3)H]SM. These results indicated that the assay of [(3)H]ceramide-to-[(3)H]SM conversion in semi-intact cells is a faithful in vitro assay for the activity of cytosol-dependent transport of ceramide and that LY-A cells are defective in a cytosolic factor involved in ceramide transport. In addition, conversion of [(3)H]ceramide to [(3)H]glucosylceramide in semi-intact cells was little dependent on cytosol, suggesting that ceramide reached the site of glucosylceramide synthesis by a cytosol-independent (or less dependent) pathway.

Serum factors governing intraerythrocytic development and cell cycle progression of Plasmodium falciparum

Malaria is clinically manifested only when the human malaria parasites in the genus Plasmodium enter the obligatory intraerythrocytic life cycle. Elucidation for the roles of the serum, the key nutrient, and its components is then deemed essential for thorough understanding of the proliferation of Plasmodium cells at the erythrocytic stage. Fractionation and analysis of serum and its components was performed by chromatography, solvent extraction, and subsequent reconstitution experiments. Only fractions containing serum albumin (SA) from the serum and purified intact bovine serum albumin (BSA) showed comparable growth promoting activity with human serum (HS). Delipidated BSA can only effect parasite growth after reconstitution with lipids extracted from intact BSA. Fatty acid (FA) species in the neutral lipid fraction from intact BSA proved likewise when reconstituted with delipidated BSA. Furthermore, the involved FA species have to come in a pair of one saturated and one unsaturated, with palmitic and oleic acids as the best combination. The results were further substantiated by morphological analysis as well as biochemical analysis of the DNA synthesis during the intraerythrocytic development. This study can be a basis to explore the molecular mechanism of lipid traffic within the parasitized red blood cell (RBC), which can be an important adjunct to the development of drugs for malaria therapy.

Flagellate mushroom (Shiitake) dermatitis and photosensitivity

Flagellate skin lesions occur in some patients after eating the mushroom Lentinus edodes, and they are called shiitake dermatitis in Japan. We describe a 44-year-old man with such skin lesions on his trunk after eating L. edodes, who developed as well photosensitive skin lesions on exposed areas. Skin phototesting with UVB did not show a decreased minimum erythema dose; UVA irradiation provoked an erythematous lesion with nonspecific histological changes. Analysis of the case histories of 94 Japanese patients with shiitake dermatitis revealed that 44 (47%) also developed dermatitis on the skin exposed to sunlight. UVA photodermatitis has not been emphasized in previous reports. The relationship to bleomycin flagellate dermatitis is discussed.