Characterization of the highly variable bioavailability of tiludronate in normal volunteers using population pharmacokinetic methodologies

Currently, the use of classical bioequivalence criteria is being called into question for certain classes of drugs such as bisphosphonates. These compounds typically possess a wide therapeutic index but may be characterized by low and variable absorption. The purpose of this communication was to characterize the highly variable bioavailability of tiludronate using a population pharmacokinetic method (NONMEM program) and compare the results to a standard 2 way cross-over bioequivalence trial in healthy subjects. Over 3500 plasma samples from 153 healthy subjects, representing 12 different clinical trials were pooled for mixed effect modeling purposes (complete data set). These studies, conducted under single and multiple dose conditions, contained all the directly comparable data available in healthy subjects administered a 400 mg dose of tiludronate. A two compartment model with first order absorption was fit to the plasma concentration-time data and a term for relative bioavailability (BA) was included. Intersubject and residual variability were modeled using a constant coefficient of variation (CCV) model. A pilot model development data set was obtained from a 24 subject cross-over bioequivalence study. Population estimates of BA and its associated 90% confidence interval of 1.12 and 0.89-1.35 compared favorably to standard bioequivalence methodology (1.15 and 0.93-1.42, respectively). Since a good fit of predicted and observed plasma concentrations as well as estimates of BA were obtained, a two compartment model with a term for BA was then applied to the complete data set. Under these conditions, BA and its 90% confidence interval were found to be 1.17 and 0.98-1.36. Intersubject variability of 31%, compared with 38% in the pilot model development data set and residual variability of 38% were seen. No differences in absorption characteristics as measured by Ka were found. Good agreement between the population pharmacokinetic parameters were observed when the pilot data set was compared with the full data set. The proposed model was confirmed by creating 10 additional smaller data sets that were matched for the number of subjects given both formulations under single and multiple dose conditions. No change in the estimate of BA was observed under these study conditions. This study demonstrated that population pharmacokinetic methodology can be applied successfully to problematical bioequivalence issues that may occur during the development process. Increasing the number of subjects in the overall analysis did not alter the estimate of BA or its 90% confidence interval, when compared to the original cross-over bioequivalence study. Bayesian approaches can be of value in large clinical trials where typically relatively few plasma samples are obtained from individual subjects.

Chinese hamster ovary cell mutants defective in glycosaminoglycan assembly and glucuronosyltransferase I

The proteoglycans of animal cells typically contain one or more heparan sulfate or chondroitin sulfate chains. These glycosaminoglycans assemble on a tetrasaccharide primer, -GlcAbeta1, 3Galbeta1,3Galbeta1,4Xylbeta-O-, attached to specific serine residues in the core protein. Studies of Chinese hamster ovary cell mutants defective in the first or second enzymes of the pathway (xylosyltransferase and galactosyltransferase I) show that the assembly of the primer occurs by sequential transfer of single monosaccharide residues from the corresponding high energy nucleotide sugar donor to the non-reducing end of the growing chain. In order to study the other reactions involved in linkage tetrasaccharide assembly, we have devised a powerful selection method based on induced resistance to a mitotoxin composed of basic fibroblast growth factor-saporin. One class of mutants does not incorporate 35SO4 and [6-3H]GlcN into glycosaminoglycan chains. Incubation of these cells with naphthol-beta-D-xyloside (Xylbeta-O-Np) resulted in accumulation of linkage region intermediates containing 1 or 2 mol of galactose (Galbeta1, 4Xylbeta-O-Np and Galbeta1, 3Galbeta1, 4Xylbeta-O-Np) and sialic acid (Siaalpha2,3Galbeta1, 3Galbeta1, 4Xylbeta-O-Np) but not any GlcA-containing oligosaccharides. Extracts of the mutants completely lacked UDP-glucuronic acid:Galbeta1,3Gal-R glucuronosyltransferase (GlcAT-I) activity, as measured by the transfer of GlcA from UDP-GlcA to Galbeta1,3Galbeta-O-naphthalenemethanol (<0.2 versus 3.6 pmol/min/mg). The mutation most likely lies in the structural gene encoding GlcAT-I since transfection of the mutant with a cDNA for GlcAT-I completely restored enzyme activity and glycosaminoglycan synthesis. These findings suggest that a single GlcAT effects the biosynthesis of common linkage region of both heparan sulfate and chondroitin sulfate in Chinese hamster ovary cells.

[Clinical features and diagnosis of cerebral venous thrombosis]

OBJECTIVE

To investigate the clinical features and imaging diagnosis of cerebral venous thrombosis.

METHODS

65 cases of cerebral venous thrombosis (CVT) were proved by angiography (n = 34) or MR (n = 44), 30 by both procedures and 6 by pathology as well. Their age ranged from 13 to 59 years (mean age 32.5), 31 were male and 34 were female.

RESULTS

The clinical manifestations were variable, but most patients had symptoms and signs of intracranial hypertension (91%)such as headache and papilledema. Nearly half of the patients had focal neurological dysfunction (49%) such as weakness of limbs and seizures and half of the patients had intracranial hypertension (51%) only. The occluded dural sinus and the clot could be visualised directly by means of magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA).

CONCLUSION

MRI and MRA are becoming the imaging investigation of choice for the diagnosis of CVT, Anticoagulation, thrombolysis and dextran may be effective measures in the treatment of cerebral venous thrombosis.

Formation of HNK-1 determinants and the glycosaminoglycan tetrasaccharide linkage region by UDP-GlcUA:Galactose beta1, 3-glucuronosyltransferases

While expression-cloning enzymes involved in heparan sulfate biosynthesis, we isolated a cDNA that encodes a protein 65% identical to the UDP-GlcUA:glycoprotein beta1, 3-glucuronosyltransferase (GlcUAT-P) involved in forming HNK-1 carbohydrate epitopes (3OSO3GlcUAbeta1,3Gal-) on glycoproteins. The cDNA contains an open reading frame coding for a protein of 335 amino acids with a predicted type II transmembrane protein orientation. Cotransfection of the cDNA with HNK-1 3-O-sulfotransferase produced HNK-1 carbohydrate epitopes in Chinese hamster ovary (CHO) cells and COS-7 cells. In vitro, a soluble recombinant form of the enzyme transferred GlcUA in beta-linkage to Galbeta1,3/4GlcNAcbeta-O-naphthalenemethanol, which resembles the core oligosaccharide on which the HNK-1 epitope is assembled. However, the enzyme greatly preferred Galbeta1, 3Galbeta-O-naphthalenemethanol, a disaccharide component found in the linkage region tetrasaccharide in chondroitin sulfate and heparan sulfate. During the course of this study, a human cDNA clone was described that was thought to encode UDP-GlcUA:Galbeta1,3Gal-R glucuronosyltransferase (GlcUAT-I), involved in the formation of the linkage region of glycosaminoglycans (Kitagawa, H., Tone, Y., Tamura, J., Neumann, K. W., Ogawa, T., Oka, S., Kawasaki, T., and Sugahara, K. (1998) J. Biol. Chem. 273, 6615-6618). The deduced amino acid sequences of the CHO and human cDNAs are 95% identical, suggesting that they are in fact homologues of the same gene. Transfection of a CHO cell mutant defective in GlcUAT-I with the hamster cDNA restored glycosaminoglycan assembly in vivo, confirming its identity. Interestingly, transfection of the mutant with GlcUAT-P also restored glycosaminoglycan synthesis. Thus, both GlcUAT-P and GlcUAT-I have overlapping substrate specificities. However, the expression of the two genes was entirely different, with GlcUAT-I expressed in all tissues tested and GlcUAT-P expressed only in brain. These findings suggest that, in neural tissues, GlcUAT-P may participate in both HNK-1 and glycosaminoglycan production.

CDK4 gene amplification in osteosarcoma: reciprocal relationship with INK4A gene alterations and mapping of 12q13 amplicons

The INK4A gene, localized to human chromosome 9p21, encodes p16INK4A, a tumor suppressor that functions at least in part through the inhibition of CDK4, a cyclin-dependent kinase encoded by a gene at 12q13. To examine INK4A gene alterations in uncultured samples of osteosarcoma and the relationship between INK4A and CDK4 alterations, we analyzed the INK4A and CDK4 genes in 87 specimens from 79 patients. INK4A deletion and CDK4 gene amplification were determined by quantitative Southern blot analysis. INK4A exon 2 was screened for mutation by polymerase chain reaction and single-strand conformational polymorphism analysis. Methylation at the CpG island in INK4A, associated with loss of p16INK4A expression, was assessed by Southern blot analysis using methylation-sensitive restriction enzymes. INK4A deletion (4/55) or rearrangement (1/55) was found in 5 of 55 cases. No INK4A exon 2 point mutations and methylation were detected. CDK4 gene amplification was found in 6 of 67 samples, but not in tumors with INK4A alteration. Amplification analysis of other genes at 12q13 (GLI, CHOP, HMGI-C and MDM2) in these 6 cases supports the view that CDK4 and MDM2 are independent targets for amplification, with variable amplification of the intervening region containing HMGI-C. Of 46 patients studied for both INK4A alterations and CDK4 amplification, the tumors in 22% contained one or the other. The prevalence of these alterations, in conjunction with the reported inactivation of RB in up to 80% of cases, suggests that genetic lesions deregulating the G1 to S cell cycle checkpoint may be an almost constant feature in the pathogenesis of osteosarcoma.

Isolation of cDNAs that cover the entire coding region of a novel human protein D40

Previously, we have reported a novel protein, D40, that specifically binds to a nuclear factor GCF by two-hybrid system. Northern analysis on tumor cell lines revealed that mRNA of D40 is about 5 kb. To get cDNA clones that cover the total coding region of D40 protein, approximately 5 x 10(5) clones of a human cDNA library were screened, and then several positive clones were obtained. RACE was performed to get the 5' end of the cDNA. DNA sequencing revealed an open reading frame that encodes a protein with 887 amino acids. in vitro transcription and translation analysis of D40 revealed that the molecular weight of the protein is 110 to approximately 130 kda.

Optimum synthesis for time scale generation

A time scale can be regarded as a synthesis of readings from precise clocks. Usually such synthesis is based on the principle of weighted averaging, which balances the contribution of each clock according to its noise level. It is well known that there are five different noise processes in precise clocks. Therefore, a good synthesis should balance each of those noise levels. Most existing algorithms control only one or two noise types. If an algorithm can control all five noise types simultaneously, we consider it to be optimum. The key point of constructing an optimum algorithm is the separation of all five noise types. In this paper, an optimum algorithm is presented using the half-integrating/half-differentiating model by which the five noise types are separated correctly. Performances of the new algorithm are demonstrated with simulated and real data.

Mycobacterial dose defines the Th1/Th2 nature of the immune response independently of whether immunization is administered by the intravenous, subcutaneous, or intradermal route

It is believed that cell-mediated immunity alone can contain Mycobacterium tuberculosis, the pathogen responsible for tuberculosis. The induction of antibody, or of a mixed cell-mediated/humoral response, is associated with tuberculous disease. It is therefore important to determine the conditions of immunization with bacille Calmette Guérin (BCG), the attenuated strain of Mycobacterium bovis used to vaccinate humans against tuberculosis, that optimally induces an exclusive cell-mediated, Th1 response. Such a determination will then allow an assessment of whether the generation of such an exclusive Th1 response results in the generation of a Th1 imprint against mycobacteria. This Th1 imprint would ensure that the Th1 response is predominant following any challenge. We therefore tested the proposition that the dose of mycobacteria used for immunization generally determines the Th1/Th2 nature of the ensuing response. Our results demonstrate that relatively low doses lead to an almost exclusive cell-mediated, Th1 response, while higher doses induce a mixed Th1/Th2 response. Furthermore, the dependence on dose is independent of whether BCG is administered intravenously, subcutaneously, or intradermally. The implications of our findings to understanding how different classes of immunity are induced, to the epidemiology of tuberculosis, and to the design of effective vaccination strategies are discussed.

Infection of glial cells by the human polyomavirus JC is mediated by an N-linked glycoprotein containing terminal alpha(2-6)-linked sialic acids

The human JC polyomavirus (JCV) is the etiologic agent of the fatal central nervous system (CNS) demyelinating disease progressive multifocal leukoencephalopathy (PML). PML typically occurs in immunosuppressed patients and is the direct result of JCV infection of oligodendrocytes. The initial event in infection of cells by JCV is attachment of the virus to receptors present on the surface of a susceptible cell. Our laboratory has been studying this critical event in the life cycle of JCV, and we have found that JCV binds to a limited number of cell surface receptors on human glial cells that are not shared by the related polyomavirus simian virus 40 (C. K. Liu, A. P. Hope, and W. J. Atwood, J. Neurovirol. 4:49-58, 1998). To further characterize specific JCV receptors on human glial cells, we tested specific neuraminidases, proteases, and phospholipases for the ability to inhibit JCV binding to and infection of glial cells. Several of the enzymes tested were capable of inhibiting virus binding to cells, but only neuraminidase was capable of inhibiting infection. The ability of neuraminidase to inhibit infection correlated with its ability to remove both alpha(2-3)- and alpha(2-6)-linked sialic acids from glial cells. A recombinant neuraminidase that specifically removes the alpha(2-3) linkage of sialic acid had no effect on virus binding or infection. A competition assay between virus and sialic acid-specific lectins that recognize either the alpha(2-3) or the alpha(2-6) linkage revealed that JCV preferentially interacts with alpha(2-6)-linked sialic acids on glial cells. Treatment of glial cells with tunicamycin, but not with benzyl N-acetyl-alpha-D-galactosaminide, inhibited infection by JCV, indicating that the sialylated JCV receptor is an N-linked glycoprotein. As sialic acid containing glycoproteins play a fundamental role in mediating many virus-cell and cell-cell recognition processes, it will be of interest to determine what role these receptors play in the pathogenesis of PML.

Expression of GCF protein is dependent on the cell cycle

GCF is reported to be a transcriptional regulator that binds to specific GC-rich sequences in the epidermal growth factor (EGF) receptor gene promotor and to represses its transcription. In this study, to examine the expression of GCF in cell cycle, we have developed antibodies against GCF protein. The anti-GCF antibody recognized a major band with a molecular weight of approximately 100 kda present in human Hela cell line by immunoprecipitation followed by Western blotting. Although GCF proteins were detected throughout the cell cycle, it reached the highest level in G1 phase, and fell down to the lowest level during G2/M phase. Thus, the expression of GCF is regulated in a cell cycle-dependent manner, suggesting a potential role of GCF in the control of cell growth.

[Reoperation for recurrent carcinoma of the esophagus and cardia]

OBJECTIVE

To review the experience of reoperation for recurrent carcinoma of the esophagus and cardia.

METHOD

Between 1979 and 1996, 44 patients with recurrent esophageal and cardiac cancer after the first operation underwent reoperation. Among them, 21 had esophageal cancer and 23 cardiac cancer. 36 patients were male and 8 female, with age ranged from 42 to 68 years.

RESULT

The resectability rate was 77.2% (34/44) and the hospital mortality rate was 5.8%. Postoperative complications occurred in 7 patients with a morbidity of 20.5%. Pathologically, previous anastomotic relapse was seen in 26 patients, recurrent lesion of residual esophagus in 7, and recurrent cancerous residue at the esophageal bed in 1. 15 patients (44%) showed lymph node metastasis. Follow-up showed that 4 patients survived for 5 years, 4 for 3 years, and 3 for 2 years. 15 patients died within one year after reoperation.

CONCLUSION

The recurrence of esophageal and cardiac cancer after first operation is not a contraindication to reoperation, but careful preoperative assessment and patients' selection should become an integral part of the evaluation of these patients.

[Math-model of efficient cultivation of Angelica sinensis]

Using two-time general rotation-constitution design, the math-mdele has been founded about Angelica sinensis prodution efficiency and quantity of nitrogen, phosphorus and potassium to use by doing experiments in many different spots and production demonstration for testing and verifying. Accordin to the modle, computer is used to simulate the better, through which people can get fresh Chinese angelica over 500 Kg per mu and also net income over 500 yuan per mu. It shows that this is the best combination. 95% density riliability for this plan is 6860-7600 plants, pure nitrogen 18.75-22.2 Kg, P2O5 9.1-11.1 Kg and K2O 4.46-5.37 Kg One mu. Proportion for nitrogen, phosphorus, potassium is 1:0.49:0.24.

[The protective effects of nerve growth factor on peripheral nerve injury]

The protective effects of nerve growth factor (NGF) on peripheral nerve injury and sensory neuron growth were studied in three models: peripheral sympathetic nerve injury induced by intraperitoneal injection of 6-hydrodopamine (6-OHDA), mechanically injured ulnar nerve and cultured dorsal root ganglion (DRG) of newborn rats in vitro. The results indicate that NGF dose-dependently increased norepinephrine content in mouse submandibular gland and cell numbers of C7 (seventh cervical vertebra), T1 (first thoracic vertebra) dorsal root ganglion in rabbits, and also dramatically promoted the growth of neuronal projections in cultured DRG. These results suggest that NGF has significant neuroprotective action in peripheral nerve injury and a strong neuronutrition on sensory neuron.

[Effects of sodium doecyl sulfate on the artificial dental plaque in chemostat]

Sodium doecyl sulfate (SDS) is widely used as a detergent in dentifrices. It has been shown to interfere with the protein adsorption to hydroxyapatite (HA), and inhibit acquired pellicle formation. The aim of the present study was to examine the effects of SDS on the artificial dental plaque in chemostat. The amount of the 3H-labelled bacteria adhered on the enamel fragment surface was determined with scintillometer. The artificial dental plaque was observed under the scanning electron microscope. The results showed that enamel fragments treated with SDS adsorbed less bacteria than untreated ones, and had no plague formed. It suggested that SDS can inhibit the bacterial adherence on enamel surface and thus reduce dental plaque formation.

Effect of tetrandrine on proto-oncogene c-fos expression in rat cerebrum

AIM

To detect the effect of tetrandrine (Tet) on c-fos gene expression in cerebrum induced by lindane, a neurotoxicant which activates Ca2+ channels.

METHODS

Northern and dot blotting, dual wavelength thin layer chromatography scanner, were used in this study.

RESULTS

Lindane 30 mg.kg-1 given by intragastric gavage (i.g.) increased the expression of c-fos gene to 146 mm2 in rat cerebrum 1 h after treatment. Tet 1, 2, and 4 mg.kg-1 given by i.g. 30 min prior to lindane reduced c-fos gene expression in a concentration-dependent manner. Expressed genes reached only 86, 40, and 39 mm2, respectively.

CONCLUSION

Tet inhibited c-fos gene expression in rat cerebrum induced by Ca2+ agonist-lindane.

[Impedance of cerebrovascular system simulated by a hemodynamic model of brain circulation]

A hemodynamics model of cerebral Willis circulation is proposed. The model consists of the compensation of blood flow as well as the compliance, resistance and inductance of arteries. The impedances of carotid and vertebral arteries are obtained by solving the govern equations. The theoretical impedances correspond well with the experimental results. The simulating results demonstrate that the alteration of the arterial dynamic parameters influences not only the ipsilateral impedance but also the contralateral arterial system. These conclusions suggest that the carotid or vertebral impedance is not suitable for describing the behaviour of its own arterial system, because the impedance is also influenced by the other arterial system and blood pressure.

[Ultrastructure of adherence of Streptococcus mutans MT8148 and its glucosyltransferase deficient mutants]

The ultrastructure of adherence of Streptococcus mutans MT8148 and its glucosyltransferase deficient mutants were compared by Scanning Electronic Microscope. Four patterns of adherence of tested strains in the presence of sucrose were observed. These results suggest that the cell-associated GTase is responsible for firm aggregation of cells. However, cell free GTase is also important in aggregation between cells.

Re-examination of 5' end of cDNA of transcription factor GCF

N-terminal region of transcriptional factor GCF was re-examined as the published amino acid sequence is extremely basic. 5'Rapid Amplification of cDNA End (5' RACE) analysis was performed and the result revealed that sequence of the first 308 bases of published GCF cDNA does not conform to the one obtained by 5' RACE. Sequence of genomic GCF DNA is consistent with the new cDNA sequence but not with the published one. Results of ordinal RT-PCR analyses are consistent with that of 5' RACE.

Hepatitis C virus (HCV)-induced IgG-IgM rheumatoid factor (RF) complex may be the main causal factor for cold-dependent activation of complement in patients with rheumatic disease

A low serum complement level is commonly found in patients with rheumatic diseases. We evaluated 170 patients with such diseases to determine their serum levels of CH50, C3 and C4 protein. Persistent hypocomplementaemia was found in 19 of those patients, particularly in those with systemic lupus erythematosus (SLE). Cold-dependent activation of complement (CDAC) was demonstrated in nine of the 19 (47.4%), and six of the nine patients demonstrated infection with HCV (66.7%). The nine patients that exhibited CDAC had nearly normal haemolytic complement activity when the sera were separated either at 37 degrees C or in EDTA-treated plasma. Conversely, it markedly decreased, even to the point of being immeasurable, when the sera were separated at 4-21 degrees C. No significant deficiency in C3 and C4 protein levels was found in these patients. Clinical parameters other than levels of anti-HCV antibody, transaminase, and RF were not influenced by CDAC. In an attempt to isolate the causal factor for CDAC, we isolated IgG fractions from the CDAC patients by using a protein G column, in which case precipitates were collected from the eluates. The precipitates were mixed with normal serum and incubated at 4-21 degrees C for 18 h. A decrease in the level of CH50 in normal serum was observed, which predominated (P < 0.001) when precipitates from HCV-infected patients were used. This indicated CDAC was possibly interrelated to the precipitates of such patients. This precipitate was proved to contain IgM besides IgG. It is therefore possible that an HCV-related IgG complex or an IgG-IgM RF complex may be formed at low temperature and be involved in activating the complement system in vitro.

Modification of vertical OKN and vertical OKAN asymmetry in humans during parabolic flight

Characteristics of human vertical optokinetic nystagmus (OKN) and afternystagmus (OKAN) were examined by ISCAN imaging system on the ground and on board NASA's KC-135 aircraft in a parabolic flight study. The aircraft produced alternating periods of micro-(ca. 10(-2) G) and hyper-(ca. 1.8 G) gravitoinertial forces. Each phase lasted approximately 20 to 25 s. As compared to the baseline data on the ground, there was a significant increase of downward OKN/OKAN, whereas the upward OKN/OKAN did not change significantly in either micro- or hyper-G. As a consequence, the asymmetry of vertical OKN/OKAN, normally seen on the ground, was lost. It is postulated that the increase of downward OKN/OKAN in non-1-G conditions was governed by two different mechanisms. In micro-G, the normal inhibition effect in 1 G on the downward eye movement mediated by otolith organ activity to vertical velocity storage was removed. In hyper-G, downward OKN/OKAN was facilitated by augmented otolith-ocular reflex because of increased gravitoinertial force, so as to produce enhanced compensatory downward eye movement.

[Intellectual status of patents cerebral cysticercosis]

OBJECTIVE

To study the intellectual status of patients with cerebral cysticercosis with dementia evaluation scale.

METHODS

The intellectual status of 112 patients with cerebral cysticercosis was studied with Hasagawa dementia evaluation scale and that of 30 patients with event related potential of P 300.

RESULTS

In the patientsl, 50.9% suffered from mental dysfunction. Among them 11.6% had severe abnormality, 13.4% moderate, and 25.9% mild. Hypertension, epileptic attack and improper medication may cause intellectual dysfunction.

CONCLUSIONS

Protection of mental function should be considered when chosing the treatment for better recovery of the patients. Hypertension, epileptic attack and improper medication may cause intellectual dysfunction.

[A comparative study of cervical and thoracic anastomoses after esophagectomy for esophageal carcinoma]

From April 1979 to December 1984, esophagectomy was performed in 552 cases of esophageal cancer of which 108 received cervical anastomosis and 444 intrathoracic anastomosis. The total postoperative complications and operative mortality rates of the two groups were very close. Leakage was significantly more frequent after cervical anastomosis, but mortality due to leakage was less frequent than that in thoracic anastomosis. The 1-, 3-, 5-, 10-year survival rates of cervical anastomosis were apparently higher than those of intrathoracic anastomosis, but the differences were not statistically significant. The 5-year survival rates of patients with the same TNM stage failed to demonstrate any significant difference between the two groups. The quality of life among the groups was satisfactory. There was no deterioration of the quality of life in cervical anastomosis. It caused less gastroesophageal reflux than did intrathoracic anastomosis. We hold that esophagectomy with cervical anastomosis and extensive lymphadenectomy is a better treatment of choice for carcinoma of the esophagus.

[Fluorometric method for determination of nitric oxide and nitric oxide synthetase in rat brain]

A simple, sensitive fluorometric method for the determination of nitric oxide and nitric oxide synthetase in rat brain homogenates has been developed. The method is based on the absorption of a reaction product of N-acetylcysteine and nitric oxide overlapping the absorption of quinine sulfate. The lowest concentration that can be determined is 3 x 10(-8) mol.L-1.

[Studies on microcystin contents in different drinking water in highly endemic area of liver cancer]

In order to study the pollution with microcystin (MC), a potent liver promoter, in drinking water in highly endemic area of liver cancer, cyanobacteria and its product MC were detected in drinking water in Haimen, Jiangsu Province during 1992 to 1993. Oscillatoria was identified as the most common species of cyanobacteria in pond-ditch and river water in Haimen, Jiangsu Province, which can produce MC. MC was detected in two of 65 water samples with high performance liquid chromatography, liquid chromatography and mass spectrography. In addition, studies were conducted in 989 samples collected from drinking water in Haimen, Jiangsu Province and more sensitive ELISA was used to detect their MC contents. Results showed proportions of samples with positive MC (greater than 50 pg/ml) were 17.3%, 31.9%, 4.3% and 0 for pond-ditch, river, shallow and deep well water, respectively, with average contents of 101, 160, 68 and 0 pg/ml, respectively. Proportions of positive MC samples and average MC contents for pond-ditch water were significantly greater than those in shallow and deep well water. It suggests studies on relationship between MC and liver cancer should be conducted further.

Percutaneous absorption of ketoprofen from different anatomical sites in man

PURPOSE

The purpose of this study was to investigate the percutaneous absorption of ketoprofen applied topically to different anatomical sites on the body.

METHODS

The study design was a randomized, four-way crossover in 24 healthy male subjects. One gram of ketoprofen 3% gel (30 mg dose) was applied every six hours for 25 doses over a 100 cm2 of the back, arm, and knee. A 0.5 ml of ketoprofen solution (60 mg/ml) was applied to the back as a reference treatment. Plasma and urine samples were obtained for the assay of racemic ketoprofen and ketoprofen enantiomers (S and R), respectively.

RESULTS

The relative bioavailabilities of ketoprofen gel were 0.90 +/- 0.50, 1.08 +/- 0.63, and 0.74 +/- 0.38 when applied to the back, arm, and knee, respectively. The plasma ketoprofen C(max) for gel applied to the back and arm are similar (p > 0.05) but C(max) was lower when applied to the knee (p < 0.05). The time to C(max) ranged from 2.7 to 4.0 hours and was similar for gel treatments on the back and arm, but no longer for the knee treatment. The fraction of dose excreted in urine as total S and R enantiomers ranged from 5.41 to 9.10%.

CONCLUSIONS

The percutaneous absorption of ketoprofen was similar when applied to either the back or arm but was lower when applied to the knee.

Formation of inclusion bodies may be the key factor for the stability of expressed products in E. coli

Des-B30 single-chain insulin gene was constructed from chemically synthesized DNA encoding human proinsulin by oligo-nucleotide induced deletion, cloned into the expression plasmid pBV220, and expressed in E. coli with a level of around 5%. The expressed product was in the form of inclusion bodies. After downstream processing, 45 mg of des-B30 single-chain insulin with a purity of up to 90% was obtained from 1 liter of high density fermentation medium. It is suggested that the fusion protein model to increase the stability of small proteins seems inadequate to some extent, the formation of inclusion bodies may be the key factor for the stability of some expressed products, large or small, in the cytoplasm of E. coli cells.

Generation and reactions of the disulphide radical anion derived from metallothionein: a pulse radiolytic study

OH-radicals were generated by pulse radiolysis of aqueous solutions of rabbit (Zn,Cd)-metallothionein (MT). They react with MT mainly by forming a thiyl radical with a rate constant of 1.7 x 10(12) dm3 mol-1 s-1. The thiyl radical reacts rapidly but reversibly with a thiolate function to form RSSR.-: RS + RS- reversible RSSR.-. The kinetics of the formation and decay of this radical anion have been studied pulse radiolytically by monitoring the evolution of the optical absorption of RSSR.- at 450 nm. This process is mostly intermolecular, i.e. bimolecular in MT. In the absence of O2, RSSR.- decays bimolecularly: RSSR.(-)+RS.-->RSSR + RS-. In the presence of O2, RS. may be scavenged by O2 and thus the yield of RSSR.- decreases: RS.+O2 reversible RSOO.. Under these conditions RSSR.- decays by first-order kinetics: RSSR.(-)+O2-->RSSR + O2.-. The rate constants of these reactions have been determined at room temperature: k4 = 1.8 x 10(9) dm3 mol-1 s-1, k5 = 7 x 10(4) s-1, k10 = 9.2 x 10(8) dm3 mol-1 s-1, and k18 about 3 x 10(7) dm3 mol-1 s-1. From the dependence of the maximal absorbance at 450 nm on the thiolate concentration in the absence of oxygen, epsilon (RSSR.-) = 9 x 10(3) dm3 mol-1 cm-1 and the stability constant (K4/5) of 2.3 x 10(4) dm3 ml-1 was determined. K4/5 is in good agreement with that determined kinetically, k4/k5 = 2.6 x 10(4) dm3 mol-1. The stability constant K15/16 of the thiylperoxyl radical, RSOO., was determined to be 5.5 x 10(3) dm3 mol-1.

Comparison of the pharmacokinetics of two nicotine transdermal systems: nicoderm and habitrol

This randomized, crossover study compared the nicotine and cotinine pharmacokinetic parameters and plasma concentration profiles of two different nicotine transdermal products: Nicoderm (Alza, Palo Alto, CA; and Marion Merrell Dow, Kansas City, MO) and Habitrol (Basel Pharmaceuticals, Summit, NJ). The two treatments were randomly assigned to each of 24 male smokers and worn for 24 hours each day for 5 days, with a 6-day washout between treatments. Plasma nicotine and cotinine concentrations were measured on day 1 and day 5 of each treatment. Mean delivered dose differed significantly between products, and the two products were not bioequivalent. The Nicoderm system provided higher mean plasma nicotine concentrations, particularly during the first 8 hours after system application. The mean steady state Cmax, AUC, and degree of fluctuation (DF) values were significantly greater for the Nicoderm system than for Habitrol. The mean nicotine tmax value for the Nicoderm system was significantly shorter (P < .001) than that for Habitrol (2.7 versus 8.6 hours). Steady state cotinine AUC values and plasma concentrations were significantly lower for Habitrol than for the Nicoderm system. The incidence of adverse events was similar for both products.

Schistosoma mansoni hexokinase: cDNA cloning and immunogenicity studies

DNA encoding a Schistosoma mansoni hexokinase (SHEX) was amplified from cDNA by the polymerase chain reaction using opposing oligonucleotide primers designed to hybridize with two short segments of hexokinase coding sequences that are well-conserved through evolution. The resulting DNA fragment was then used as a probe to identify a full-length hexokinase cDNA clone. SHEX cDNA encodes a 50-kDa protein that is approximately 46% homologous to rat hexokinase, 40% to rat glucokinase, and 34% to yeast hexokinase A. SHEX coding DNA was expressed within Escherichia coli cells and the 50-kDa recombinant product (rSHEX) was partially purified. Mice repeatedly immunized with rSHEX produced antibodies which recognize rSHEX but this offered no significant protection against subsequent cercarial challenge. On Western blots, rSHEX is weakly recognized by antisera against rat brain hexokinase but not by sera from three strains of mice experimentally infected with S. mansoni parasites or from numerous human schistosomiasis patients. Thus, unlike other reported S. mansoni glycolytic enzymes, hexokinase appears to be poorly immunogenic during schistosome infection and of limited potential as a vaccine candidate.

Double-C-peptide human proinsulin

A fusion gene encoding double-C-peptide human proinsulin was constructed by insertion of a DNA fragment encoding human C-peptide into the 5'-terminal C-peptide coding sequence of a synthetic human proinsulin gene with correct reading frame and over-expressed in E. coli. The purified double-C-peptide human proinsulin shows decreased activity in receptor binding and insulin immune assays as compared with human proinsulin. Disulphide bond reconstitution studies demonstrate that there is not much more influence of the protein concentration on the yield of refolded double-C-peptide human proinsulin. The double-C-peptide human proinsulin shows a 1.86-fold human C-peptide immune activity as compared with that of human proinsulin and gives a good yield of the molecule with correct disulphide bonds in reconstitution studies strongly suggesting the existence of very flexible conformation of the C-peptide.

Metal-Directed Synthesis of Dithia Diaza Macrocycles Carrying Pendant Alcohol and Also Nitro or Carboxylate Groups

Copper(II)-directed condensation of 1,9-diamino-3,7-dithianonan-5-ol with nitroethane or di-ethyl malonate yields (6-methyl-6-nitro-1,11-dithia-4,8-diazacyclotetradecan-13-ol)copper(II) and (diethyl 13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6,6-dicarboxylate)copper(II) respectively in good yields, with the latter readily converted by decarboxylation into the complex of ethyl 13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6-carboxylate. Analogues without the alcohol group based on 3,7-dithianonane-1,9-diamine are also described. The pendant alcohol group fused directly to a macrocyclic ring carbon can act as an axial donor group, as illustrated in the X-ray crystal structure analysis of (diethyl 13-hydroxy-1,11-dithia-4,8-diazacyclotetradecane-6,6-dicarboxylate)copper(II) perchlorate . This complex crystallizes in the P21/c space group, a 12.650(3), b 8.620(1), c 24.382(4) Ǻ, β 96.10(2)°. The copper ion lies in a distorted square-based pyramidal environment of two sulfur donors (average Cu-S 2.338 A), two nitrogen donors (average Cu-N 2.035 Ǻ) and the pendant alcohol donor [Cu-O 2.319(6) Ǻ], with the copper ion displaced slightly (0.043 Ǻ) out of the macrocycle donor plane towards the pendant alcohol donor.

The germline: familiar and newly uncovered properties

Transplantations of both Drosophila pole cells and mouse primordial germ cells suggest that the pregonadal germline of these two organisms is not pluripotent. In mouse PGCs, however, the potential for activating pluripotency is clearly present, as seen in the relative case of deriving EG cells from migratory-stage PGCs. EG cells are derived from altering the in vitro growth conditions of PGCs by the addition of one factor. Conceivably, straying of PGCs in vivo could also lead to novel fates if they migrated into a suitable environment. Aberrant PGC migration underlies models for the origin of several tumor types. How are migratory-stage PGCs prevented from adopting alternative fates in wild-type development? One solution is to link accurate migration into the gonads with germ cell survival. One mechanism of accomplishing this is through the action of pleiotrophic factors such as Steel. Steel is both a proliferation and migration factor; sterility in Steel mutants is due to poor germ cell survival and improper migration. Networking of migratory PGCs is another mechanism to reduce the chances of individual germ cells straying from the migration path. Postmigratory germ cells apparently undergo another restriction on potency--novel imprinting. Assuming that EG methylation profiles accurately reflect modifications made in their founder PGCs, then "erased" pluripotent EG lines suggest that PGCs can be diverted from the germline lineage. Direct assays on PGCs show that the unmethylated phenotype at Igf2r region 2 is characteristic of late germ cells. The maintenance of germline-like methylation with a switch in PGC fate is somewhat analogous to the situation in lag mutants from Volvox, which retain large gonidial-sized cells that can nevertheless initiate somatic differentiation. Just as it is not possible to readjust cell size with a subsequent change in gonidial differentiation, it may be difficult, without gametogenesis, to reimpose methylation modifications once they have been erased. In addition, the methylation status of some sites/loci may be inconsequential to developmental gene activity in germ cells or EG cells. Recent studies indicate that the methylation imprint at Igf2r is not interpreted at functional level until embryogenesis (51). In summary, we have reviewed some distinctive properties of the development of germ cells, from their early segregation, mitotic and meiotic profile, sex determination, to their migration and sequestration into gonads. Some constraints on development of the germline likely serve to maintain its integrity until maturation, when the gametic genomes must be capable of initiating embryonic development. To accomplish this ultimate goal, germ cells in some organisms may retain a bias towards pluripotency throughout development.(ABSTRACT TRUNCATED AT 400 WORDS)

Two N-acetylglucosaminyltransferases catalyze the biosynthesis of heparan sulfate

We report that two N-acetylglucosaminyltransferases catalyze the biosynthesis of heparan sulfate in Chinese hamster ovary cells. The first enzyme initiates heparan sulfate biosynthesis and can be measured by the transfer of GlcNAc from UDP-GlcNAc to GlcUA beta 1-3Gal beta 1-O-naphthalenemethanol. The second enzyme catalyzes the polymerization of heparan sulfate and can be measured by the transfer of GlcNAc from UDP-GlcNAc to the nonreducing terminal GlcUA present in oligosaccharide fragments prepared from the Escherichia coli K5 capsular polysaccharide, N-acetylheparosan. Kinetic characterization of the initiating GlcNAc-transferase (alpha-GlcNAc-TI) indicates an apparent Km for UDP-GlcNAc of 36 +/- 4 microM. The apparent Km for UDP-GlcNAc of the polymerizing GlcNAc-transferase (alpha-GlcNAc-TII) is 230 +/- 30 microM. Both enzymes have broad pH optima and require a divalent cation for activity. alpha-GlcNAc-TI can use both Mn2+ and Ca2+, while alpha-GlcNAc-TII will use only Mn2+. Chinese hamster ovary cells deficient in the synthesis of heparan sulfate and lacking alpha-GlcNAc-TII activity and S49 Thy 1-a lymphoma cells deficient in alpha GlcNAc addition to phosphatidylinositol have wild-type alpha-GlcNAc-TI activity. Thus, distinct alpha-GlcNAc-transferases catalyze the initiation and polymerization of heparan sulfate.