Genomic organization and identification of an enhancer element containing binding sites for multiple proteins in rat pituitary tumor-transforming gene

The rat pituitary tumor transforming gene (PTTG) genomic structure was characterized in this study. Northern blot analysis showed that PTTG mRNA is highly expressed in testicular cell lines. Transfection of testicular cell lines with fusion constructs containing various portions of PTTG 5'-flanking sequences linked to luciferase showed that at least 745 base-pair (bp(s)) 5'-flanking sequences are required for PTTG transcriptional activation. DNaseI footprinting assays indicated that nuclear protein(s) from testicular cell lines interacts with PTTG 5'-flanking sequence between -509 and -624 bp, including two consensus Sp1 binding sites. Western and Southwestern blot analysis showed that three nuclear proteins in addition to Sp1 protein specifically interact with this DNA sequence and that two of these proteins are testicular cell-specific. Deletion of this 115-bp sequence from PTTG promoter resulted in complete loss of promoter function. Site-directed mutagenesis within the Sp1 consensus sequences indicated that the Sp1 binding sites are not critical components of the enhancer sequence for PTTG trancriptional activation in testicular cell lines. Finally, the 115-bp enhancer sequence was shown to be able to activate transcription from a heterologous promoter. These results suggest that PTTG transcriptional activation in testicular cell lines involves interactions of multiple nuclear factors with the PTTG 5' enhancer sequence.

Genomic structure and embryonic expression of the rat type 1 vasoactive intestinal polypeptide receptor gene

The genomic structure of the rat vasoactive intestinal polypeptide type 1 receptor (VIPR I) gene was characterized using polymerase chain reactions (PCR) and DNA sequencing. These studies show that the rat VIPR I gene spans more than 20 kb of DNA sequence and includes thirteen exons separated by twelve introns, ranging from 0.2 to 4.5 kb. VIP is known to play an important role early in embryonic development. To elucidate the receptor-mediated biological functions of VIP in development, the temporal and spatial expression of VIPR I during rat embryonic development was examined in this study. Using in situ hybridization histochemistry with 35S-labeled riboprobe, VIPR I mRNA was detected as early as embryonic day 11 (E11), in the neuroepithelium, foregut, heart and in cells lining the blood vessels. From E14 through E18, VIPR I mRNA was detected in multiple tissues derived from all three germ layers. These include neuronal cells in brain and spinal cord (ectoderm); smooth muscle cells of intestines, cells lining the wall of the heart and blood vessels, kidney, adrenal gland (mesoderm); epithelial cells of airway and of liver (endoderm). The early onset and wide tissue expression of VIPR I suggests that binding of VIP to this receptor may play an important role in rat embryonic development.

[Studies on the mechanism of protection of cultured neurous by ketamine anoxia/reoxygenation-induced injury]

The effects of anoxia/reoxygenation (A/R) and glutamate on cultured cortical neurons from 16 to 18-day-old fetal rats and the protective effect of ketamine were studied. The 12-day cultures of 12 days were exposed to anoxia (5 h) followed by reoxygenation (0-24 h). Following progressive A/R, the release of lactate dehydrogenase (LDH) into the bathing medium obviously increased and exogenous glutamate (3 h) also markedly increased the release of LDH. When the cultures were pretreated with ketamine before A/R, the amounts of LDH efflux in culture medium were significantly less than those of controls. These results demonstrate that the cultured cortical neurons are seriously damaged by A/R and exogenous glutamate. Such damage could be attenuated by ketamine, suggesting that the neurotoxic effect of glutamate and NMDA (N-methyl-D-aspartate) receptors play an important role in the process of ischemia-induced damage in the brain.

Isolation and characterization of a pituitary tumor-transforming gene (PTTG)

Pathogenesis of tumor formation in the anterior pituitary has been intensively studied, but the common mechanism involved in pituitary cell transformation and tumorigenesis remains elusive. In this study, we used mRNA differential display PCR to identify mRNAs that are differentially expressed in rat pituitary tumor cells compared with normal pituitary tissue. An mRNA exclusively expressed in pituitary tumor but not in normal pituitary was characterized. Using this pituitary tumor-specific PCR product as a probe to screen a cDNA library constructed from rat pituitary tumor GH4 cells, a cDNA of 974 bp was isolated. This cDNA encodes a novel protein of 199 amino acids, which contains no well characterized functional motifs. The mRNA of this cDNA is detected in normal adult testis and in embryonic liver, where the transcript is about 300 bp shorter and expressed at a much lower level than that detected from pituitary tumor cells. Overexpression of this protein in mouse 3T3 fibroblasts shows that it inhibits cell proliferation and induces cell transformation in vitro. Injection of transfected 3T3 cells into athymic nude mice resulted in tumor formation within 3 weeks in all animals. These results indicate that pituitary tumor cells express a unique and potent transforming gene (PTTG), which may play a role in pituitary tumorigenesis.

Considerations for toxicology studies of respiratory drug products

The standard approaches for the preclinical development of chronically administered drugs also apply to most respiratory drugs. Modifications from the standard preclinical development plan, however, may be necessary if the drug is administered intranasally or by inhalation. Administration by these routes may result in airway toxicity and the intended patient population is often particularly susceptible. Current and former representatives of the Division of Pulmonary Drug Products (CDER, U.S. FDA) present this article to describe general principles of preclinical development for respiratory drug indications. The article addresses drugs intended for administration by the intranasal or inhalation routes. The article describes the types of studies recommended, considers the initial human dose, and discusses dose-escalation strategies in clinical trials. Other areas of special concern with intranasal or inhalation administration include immunotoxicity, reproductive toxicity, types of dosing apparatus, excipients and extractables, and formulation changes. The approaches described in this article are intended as general information and should be adapted to the scientific considerations and circumstances of a particular drug under development.

[Studies on mechanism of the inhibition of Ca2+/CaM PKII activity induced by hypoxia in rat hippocampal slices]

The effects of Ca2+ and ketamine on Ca2+/CaM PK II activity in rat hippocampal slices under in vitro hypoxic states have been studied and the effect of hypoxia on glutamate accumulation was also investigated. The results were as follows: (1) Ca2+/CaM PK II activity decreased gradually with increasing hypoxic time in culture medium with or without 1.3 Ca2- mmol/L, with the former case being much more pronounced. (2) Extracellular accumulation of GLU increased about two-fold after hypoxia for 30 min in vitro. (3) When slices were incubated for 30 min under conditions in excess of exogenous GLU the enzyme activity markedly decreased, a finding suggesting that the inhibition of enzyme activity induced by hypoxia may result from excitotoxicity. (4) The inhibition of the enzyme activity induced by either hypoxia or excess exogenous glutamate alone could be antagonized markedly by pretreatment with ketamine, suggesting that the hypoxia induced inhibition of the enzyme activity is mediated by NMDA receptor.

[Treatment of nerve root avulsion of brachial plexus by nerve transfer]

The results of nerve transposition for root avulsion of brachial plexas in 21 cases were reported. The methods of the nerve transposition were divided into four groups as followings: By transfer of phrenic nerve, accesory nerve, the motor branches of cervical plexus and intercostal nerves in cease; By transfer of phrenic nerve, accessory nerve and the motor branches of cervical plexus in 6 cases; By transfer of phrenic nerve and accessory nerve in 9 cases, and by transfer of phrenic nerve or the motor branches of cervical plexus or intercostal nerve in 5 cases. During operation, in 1 cases variation of the brachial plexus was found. Injury to the subclavian artery occurred in 4 cases and they were repaired, which is good for the blood circulation of the upper arm and nerve regeneration. Nineteen cases were followed up with good results. The overall excellent and good rate was 73.7%. It was considered that transposition of nerve should be a routine operation for the treatment of root avulsion of brachial plexus and the accompanied arterial injury should be repaired at the same time during operation, and the latter would be advantageous to enhance functional recovery of nerve.

Polymorphisms of the human lipoprotein lipase gene: possible association with lipid levels in patients with coronary heart disease in Beijing area

The polymorphisms (Pvu II and Hind III) on the lipoprotein lipase (LPL) gene locus was investigated in a sample of 100 patients surviving previous myocardial infarction and 100 age matched healthy individuals selected from Han Chinese of Beijing area. In patient group a strong association was found between H+ allele of Hind III polymorphism and raised TG levels (P < 0.01). In control group P-P- genotype was observed to be associated with higher TG levels compared with P+P genotype of Pvu II polymorphism (P < 0.05). Combination of H+H+ genotype with P-P- genotype showed the highest TG levels among all nine kinds of genotypic combinations in patient group (P < 0.01). However, comparison of distribution of alleles and genotypes of these polymorphisms between patient group and control group demonstrated no significant difference. Our data suggest that the polymorphisms at the LPL gene, as the linkage markers with an aetiologic mutation at or around LPL gene, may constitute one of the genetic determinants for the population variation in plasma TG levels, as well as for the common dyslipidemia in Chinese populations.

Identification of a negative glucocorticoid response element in the rat type 1 vasoactive intestinal polypeptide receptor gene

Glucocorticoids play important roles in lung development and function by modulating the expression of a variety of genes. The type 1 vasoactive intestinal polypeptide (VIP) receptor gene is highly expressed in the lung where it mediates VIP physiological functions. In this study, the effect of glucocorticoid on VIP receptor gene expression was examined. Dexamethasone (100 n) suppresses endogenous VIP receptor mRNA expression in cultured lung cells. Transient transfection of lung cells with fusion constructs containing various portions of the VIP receptor 5'-flanking sequences linked to the luciferase reporter gene shows that 126 base pairs (bp) of the VIP receptor upstream sequences are sufficient to mediate transcriptional repression by glucocorticoid. DNase I footprinting demonstrates that purified glucocorticoid receptor (GR) binds to the VIP receptor promoter between -21 and -36 bp relative to the transcription start site. Point mutations within this binding site not only abolish GR binding and GR-mediated transcriptional repression of the VIP receptor gene, but basal transcription is also reduced to background levels. Co-transfection of GR expression vector and the VIP receptor GR binding site linked to the thymidine kinase promoter and luciferase shows that this sequence is sufficient to confer glucocorticoid-mediated transcriptional repression to a heterologous promoter. These results indicate that the VIP receptor gene contains a negative glucocorticoid response element between -21 and -36 bp that may act to regulate both basal and glucocorticoid-mediated expressions of the VIP receptor gene in lung cells.

Remission of acromegaly caused by pituitary carcinoma after surgical excision of growth hormone-secreting metastasis detected by 111-indium pentetreotide scan

GH-secreting carcinomas of the pituitary are extremely rare. We describe a 37-yr-old woman with refractory acromegaly 15 yr after transphenoidal surgery and radiotherapy, with no evidence of a recurrent pituitary mass. Scanning with 111-indium pentetreotide revealed an area of intense activity in the left neck. A 3.5 x 2.5-cm mass was excised from the neck after demonstrating an arterio-venous GH gradient of 7:1. GH levels (50 ng/mL) dropped to 0.8 ng/mL 3 h after surgery and remained normal. GH gene expression was demonstrated in the metastasis by Northern and Western blot analyses and by positive immunocytochemistry and immunoelectron microscopy. In vitro cultured cells responded to GHRH and TRH by increasing GH levels (P < 0.01). Medium GH was identical to authentic pituitary GH, as demonstrated by high pressure liquid chromatography. RT-PCR of hypothalamic hormone receptor messenger RNA in the mass revealed somatostatin receptor subtypes 2, 3, and 5 and GHRH, TRH, and dopamine receptor expression. No GH gene amplification, rearrangement, or gsp mutation was found. RB gene deletion and H-ras mutations, previously reported in PRL- and ACTH-secreting carcinomas, were not detected. In conclusion, clinical and molecular features of a GH-secreting pituitary carcinoma are presented. This metastatic lesion synthesized GH and expressed functional hypothalamic hormone receptors.

Antagonism of the lethal effects of paraoxon by carrier erythrocytes containing phosphotriesterase

Annealed murine erythrocytes were employed as a carrier model to antagonize the toxic effects of organophosphorus agents. These resealed cells containing a recombinant phosphotriesterase provided striking protection against the lethal effect of paraoxon, an active metabolite of an agricultural pesticide, parathion. Phosphotriesterase hydrolyzes paraoxon to the less-toxic 4-nitrophenol and diethylphosphate. This enzyme was encapsulated into carrier erythrocytes by hypotonic dialysis with subsequent resealing and annealing. These carrier cells were administered to mice either alone or in combination with pralidoxime (2-PAM) and/or atropine. The recipient animals were subsequently challenged with paraoxon and a marked protection was noted. Protection of free enzyme and encapsulated enzyme was compared and the encapsulated enzyme was found to persist longer and possess much greater efficacy. Less serum cholinesterase inhibition also was observed with this enhanced protection. These results indicate that the erythrocyte carrier alone is quite effective in the antagonism of organophosphorus intoxication. Moreover, when these carrier cells were administered in combination with 2-PAM and/or atropine, a marked synergism was observed.

Gender differences in the metabolism of 1,3-butadiene in Sprague-Dawley rats following a low level inhalation exposure

1,3-Butadiene (BD), a compound used extensively in the rubber industry, is carcinogenic in the male and female Sprague-Dawley rats after chronic exposures to 1000 and 8000 p.p.m. In terms of incidence of tumors the majority were in mammary tissue, thus the incidence of tumors in female rats exceeded that in males in chronic carcinogenicity studies. In the present study the production and disposition of butadiene monoepoxide (BDO) and butadiene diepoxide (BDO2), mutagenic BD metabolites, were examined in male and female Sprague-Dawley rats following a low level inhalation exposure to BD. The rats were exposed to a target concentration of 62.5 p.p.m. BD by nasal inhalation for 6 h. Immediately after exposure blood, bone marrow, lung and fat samples were removed from all the animals and mammary tissue was removed from females. The samples were prepared by cryogenic-vacuum line distillation and analyzed for the epoxides using multidimensional gas chromatography-mass spectrometry. Levels of BDO in the blood were 25.9 +/- 2.9 and 29.4 +/- 2 pmol/g in male and females respectively. The levels of this metabolite were also similar in males and females in the other tissues examined. The greatest amounts of BDO were in fat (175 +/- 21 and 203 +/- 13 pmol/g in males and females respectively). Levels of BDO2 were approximately 5-fold greater in the blood of female rats compared with male rats. In the other tissues examined BDO2 was also consistently greater in tissues from females. In fat BDO2 was present at a concentration of 7.7 +/- 1.3 and 1.1 +/- 0.1 pmol/g tissue in females and males respectively. Mammary tissue from female rats contained 10.5 +/- 2.4 pmol/g BDO2, a level slightly lower than that observed in blood. The ratios of the two epoxides differed markedly between males and females in all tissues examined. Differences were most pronounced in lung and fat tissues, where BDO/BDO2 ratios were 9 and 0.6 (lung) and 159 and 26 (fat) for males and females respectively. This study is the first to describe a gender difference in the metabolism of BD. The greater production of the highly mutagenic BDO2 in females may play a role in the increased incidence of mammary tumors after chronic exposure to BD.

[Clinical research of muscular relaxation induced by alcuronium and pancuronium]

The clinical experiment was designed for observing effect of muscular relaxation induced by alcuronium and pancuronium. 40 patients were randomly divided into alcuronium group (A) and Pancuronium group (P). A group and P group were redivided into A1,A2 groups and P1,P2 groups according to differences of the initial doses of muscle relaxants. The results of neuromuscular monitoring indicate that onset time and main-tenance time of 0.3 mg/kg alcuronium were respectively 2.4 min and 63 min; 0.1 mg/kg pancuronium were 2.7 min and 70 min. The initial doses mentioned above are suitable to intubation of anesthesia and meet surgical need for muscular relaxation. The changes of MAP,HR,blood kalium and natrium were not evident in statistical significance before and after administration of relaxants.

Characterization of the rat vasoactive intestinal polypeptide receptor gene 5' region

The broad spectrum of vasoactive intestinal polypeptide (VIP) cellular functions are mediated by high-affinity binding sites. To determine regulation of the VIP receptor gene expression, we have isolated and characterized two genomic clones that contain the first three exons and the 5' flanking region of the VIP receptor gene. Using RNase protection assays, receptor gene expression was detected in adult rat lung, liver and intestine, but not in fetal lung, indicating that VIP receptor is expressed in diverse tissues, and its expression is differentially regulated during lung development. The transcription start site of the gene was mapped to a cytosine residue, 76 bp upstream from the ATG initiation codon. Transfection into rat lung cell lines shows that although 126 bp of the VIP receptor 5' DNA sequences are capable of activating VIP receptor gene basal transcription 30-fold over a promoterless control, 488 bp of the 5' sequences further induce this activation to 97-fold over control. However, inclusion of up to 859 bp 5' sequences results in a decrease in basal promoter activity (31-fold over control), indicating that while sequences between -126 and -488 bp contain potential enhancer sequences, sequences between -488 and -859 bp may include a transcriptional repressor sequence. Deletion analysis shows that transcription factor Sp1 plays an important role in activating basal promoter of the VIP receptor gene. DNase I footprinting and gel-mobility-shift assays show that Sp1 binds to its consensus binding sites in the VIP receptor promoter, suggesting that interaction of Sp1 with VIP receptor promoter transactivates this gene.

Frequent loss of heterozygosity at the retinoblastoma susceptibility gene (RB) locus in aggressive pituitary tumors: evidence for a chromosome 13 tumor suppressor gene other than RB

Mice bearing retinoblastoma susceptibility gene (RB) germ-line mutations almost invariably develop pituitary neoplasms. We therefore tested 17 patients with pituitary tumors for loss of heterozygosity (LOH) using an RB sequence polymorphism and 5 polymorphic microsatellite markers surrounding the RB gene on the long arm of chromosome 13. In all of the 13 malignant or highly invasive pituitary tumor cases, and in 4 of their respective metastases, a RB allele was lost. In contrast, no LOH at the RB locus was detected in 4 benign pituitary adenoma cases. Three invasive tumors also lost a portion of 13q, which included D13s137, D13s133, and D13s118 telomeric and centromeric to RB, respectively. Immunohistochemical analysis, however, revealed the presence of RB protein in tumors with LOH and the RB locus. Therefore, although inactivation of RB may play a role in the development of invasive pituitary adenomas and carcinomas in mice, another tumor suppressor gene on 13q is likely involved in human pituitary tumor progression. LOH of 13q markers may also be of predictive value in determining the biological behavior of pituitary macroadenomas and their progression to invasiveness and frank malignancy.

Cyanide antagonism with carrier erythrocytes and organic thiosulfonates

Previous studies reported that resealed erythrocytes containing rhodanese (CRBC) and NA2S2O3 rapidly metabolize cyanide to the less toxic thiocyanate both in vitro and in vivo. This provided a new conceptual approach to prevent and treat cyanide intoxication. Although the rhodanese-containing carrier cells with thiosulfate as the sulfur donor were efficacious, this approach has potential disadvantages, as thiosulfate has limited penetration of cell membrane and product inhibition of rhodanese can occur due to inorganic sulfite accumulation. In order to circumvent substrate limitation and product inhibition by sodium thiosulfate, organic thiosulfonates were explored. These thiosulfonates have higher lipid solubility than thiosulfate and therefore can replenish the depleted sulfur donor, as they can readily penetrate cell membranes. Also, product inhibition of rhodanese is less apt to occur. This change in sulfur donors should greatly enhance cyanide detoxication, replenish the sulfur donor, and minimize product inhibition of rhodanese. Present studies demonstrate the enhanced efficacy of exogenous organic thiosulfonates over sodium thiosulfate in the CRBC antidotal system to detoxify the lethal effects of cyanide either alone or in combinations with exogenously administered NaNO2. Murine carrier erythrocytes containing purified bovine liver rhodanese were administered intravenously into male Balb/C mice. Subsequently, butanethiosulfonate (BTS) or Na2S2O3 (ip), and NaNO2 (sc) were co-administered prior to KCN (sc). Potency ratios, derived from the LD50 values, were compared in groups of mice treated with CRBC-Na2S2O3 or CRBC-BTS either alone or in combination with NaNO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Spectrophotometric determination of paraoxonase within mouse carrier red blood cells

A method has been developed to continuously measure paraoxonase activity spectrophotometrically in carrier red blood cells (RBCs) containing paraoxonase. This enzyme has a broad substrate specificity that includes parathion, paraoxon, soman, sarin, di-isopropyl fluorophosphate and many other organophosphorus compounds. Paraoxon is hydrolysed by paraoxonase to the less toxic 4-nitrophenol and diethyl phosphate. Determination of enzymic activity was based on the liberation of 4-nitrophenol in the presence of mouse RBCs. Paraoxonase was encapsulated within murine RBCs by hypotonic dialysis with subsequent resealing and annealing. The enzyme within resealed RBCs actively hydrolyses paraoxon in biological fluids to its less toxic metabolites. Paraoxonase incorporated within RBCs, like other enzymes, was found to be quite stable once encapsulated into RBCs and this formed the basis for this spectrophotometric method. Increasing absorbance at 400 nm indicated paraoxon hydrolysis and was the basis employed to determine enzymic activity. The Km of the enzyme within erythrocytes was 0.04 mM. This method offers a convenient, rapid and continuous way to monitor paraoxonase activity inside the carrier cell.

Antagonism of the lethal effects of cyanide by a synthetic water-soluble cobalt(III) porphyrin compound

Efficacy of hydroxocobalamin (vitamin B12) as a cyanide antidote is limited by its high molecular weight (1355 g/mol) and by the competitive binding of the cobalamin dimethylbenzimidazole. The present study describes experiments with a lower molecular weight cobalt porphyrin that has a high affinity for cyanide, Co(III)-5,10,15,20-tetrakis(4-sulfonatophenyl) porphyrin (CoTPPS), which was prepared by the method of Herrmann et al. (1978). CoTPPS was synthesized and its efficacy as an antidote to the lethal effects of cyanide either alone or in various combinations with NaNO2 and/or Na2S2O3 was determined. The LD50 value for CoTPPS was found to be 334 mg/kg. These studies were conducted using the CoTPPS LD01, 200 mg/kg. The cyanide antagonists NaNO2 (0.1 g/kg, sc), Na2S2O3 (1.0 g/kg, ip), and CoTPPS (0.2 g/kg, ip) were administered at 45, 15, and 10 min respectively prior to graded doses of KCN (sc). The LD50 values for KCN in male Swiss-Webster mice were calculated by probit analysis at the 95% confidence level and the various treatments were compared by potency ratios. These results indicated that the administration of CoTPPS alone protects against the lethal effects of cyanide. Moreover, CoTPPS adds to the protection provided by Na2S2O3 and/or NaNO2. Efficacy of this antidote is probably related to the binding equilibrium between CoTPPS and cyanide.

Encapsulation of rhodanese and organic thiosulfonates by mouse erythrocytes

A series of organic thiosulfonates were synthesized and studied as sulfur donor substrates for rhodanese encapsulated within murine carrier erythrocytes. Previous studies have indicated that resealed erythrocytes containing rhodanese (CRBC) and sodium thiosulfate can rapidly metabolize cyanide to the less toxic thiocyanate. This thiosulfate-rhodanese system was very efficacious as a new conceptual approach to antagonize cyanide intoxication both in vitro and in vivo. However, its potential is restricted because of the limited availability of thiosulfate due to its poor permeability through RBC membrane. Present studies suggest that there are advantages in using alternative sulfur donors, i.e., organic thiosulfonates in this rhodanese-containing resealed erythrocyte system, since these compounds have higher lipid solubility than inorganic thiosulfates and can readily penetrate the red blood cell membrane. Therefore, this system could provide a virtually unlimited amount of sulfur donor to the encapsulated rhodanese even if the substrates are in solution outside the cells. Moreover, the rhodanese reaction rate of any of these organic thiosulfonates is much faster than the rate observed with the classic cyanide antidote, sodium thiosulfate. This CRBC system will continue to detoxify cyanide even when these encapsulated sulfur donors are depleted, as the lipid soluble organic thiosulfonate outside the cells will diffuse past the membrane into the cell to replenish the sulfur donor. The encapsulation efficiency for rhodanese is about 30%, and the velocity of the rhodanese reaction increases linearly with the volume of enzyme-laden erythrocytes. Similarly, reaction velocity increases linearly with substrate concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

H-ras mutations in human pituitary carcinoma metastases

Molecular mechanisms of pituitary tumorigenesis were studied using Polymerase chain reaction-single stranded conformational polymorphism with DNA sequencing to identify potential mutations in the ras protooncogenes and the tumor suppressor gene p53 in invasive pituitary adenomas and carcinomas. Sequencing of exons 5 through 8 of the p53 gene revealed no mutations, nor were mutations detected in the N- or K-ras protooncogenes in four of the carcinomas and their respective metastatic deposits. Point mutations of H-ras however, were identified in three distant metastatic pituitary tumor secondaries, but not in their respective primary pituitary carcinomas, or in six invasive adenomas. Two of the mutations included a G to C substitution at codon 12, and a G to A substitution at codon 18, resulting in a glycine to arginine, and an alanine to threonine change at these amino acids, respectively. A third mutation involved a single base pair (adenine) deletion in codon 3 of H-ras which causes a frame shift, resulting in a termination signal at codon 19. These results suggest that point mutations in p53 and ras are not associated with pituitary tumorigenesis, however, point mutations of the H-ras gene may be important in the formation and or growth of pituitary metastases. This observed genomic instability will be of value in predicting the potential metastatic behavior of these aggressive pituitary tumors.

Prevalence of rheumatic diseases in Taiwan: a population study of urban, suburban, rural differences

OBJECTIVE

To determine the prevalence of symptomatic rheumatic disease in rural, urban and suburban areas of Taiwan by a 2-staged population survey.

METHODS

Nine thousand subjects over 20 years old were sampled proportional to age and sex for the area from 3 administrative areas in Taiwan. A pretested questionnaire to screen for potential rheumatic disorders and/or disability was administered in the communities by health workers. Subjects who screened positive were examined by a rheumatologist who assigned a final diagnosis based on established criteria.

RESULTS

A total of 8998 persons over age 20 residing in Hen-San (rural area), Sien-Dien (suburban), and Cu-Tien (urban) were studied. Twenty-five percent (2272) of the population indicated rheumatic problems: 1124 of 2271 were evaluated by a rheumatologist with serological and radiological testing. The response rates were 49.7% in Hen-San, 50.7% in Sien-Dien and 48.5% on Cu-Tien. After age and sex adjustment, the prevalence of rheumatic symptoms in Hen-San, Sien-Dien, and Cu-Tien was 24.3, 18.4 and 26.3% respectively. It was significantly higher in rural Hen-San and urban Cu-Tien than in Sien-Dien. The prevalence of rheumatoid arthritis (RA) in Hen-San, Sien-Dien, and Cu-Tien was 0.26, 0.78, and 0.93%, osteoarthritis (OA) was 6.3, 5.8, 5.1%, ankylosing spondylitis (AS) was 0.54, 0.19, 0.4%, gout was 0.16, 0.67, 0.67%, respectively. The prevalence of RA in Sien-Dien and Cu-Tien was significantly higher than in Hen-San (p < 0.05) but were not statistically different for OA, AS and gout among those 3 sites. Only one case of systemic lupus erythematosus (SLE) was found in urban Cu-Tien for a prevalence of 0.033%.

CONCLUSION

Our results suggest that the prevalence of RA and AS is similar to that reported in Caucasians. We could not confirm anecdotal reports that SLE was common or that it is more common than RA in people of Chinese ancestry. The prevalence of OA of the hip is comparatively uncommon in our population. The difference in prevalence of rheumatism, RA, OA and gout in these areas suggests areas of further study.

Encapsulation of phosphotriesterase within murine erythrocytes

A new conceptual approach was employed to antagonize organophosphorus intoxication by using resealed carrier erythrocytes containing a recombinant phosphotriesterase. This enzyme has been reported to hydrolyze many organophosphorus compounds, including paraoxon, a potent cholinesterase inhibitor. Paraoxon is rapidly hydrolyzed by this enzyme to p-nitrophenol and diethylphosphate. Incorporation of phosphotriesterase within resealed murine erythrocytes was accomplished by hypotonic dialysis. The properties of this enzyme within these resealed erythrocytes were investigated. Addition of paraoxon to reaction mixtures containing these resealed erythrocytes loaded with phosphotriesterase resulted in the rapid hydrolysis of paraoxon. Hydrolysis of paraoxon did not occur when these carrier erythrocytes contained no phosphotriesterase. These in vitro studies suggest that carrier erythrocytes may be developed as an approach for the prophylactic and therapeutic antagonism of organophosphorus intoxication.

The encapsulation of squid diisopropylphosphorofluoridate-hydrolyzing enzyme within mouse erythrocytes

This study describes the entrapment of squid-type diisopropylphosphorofluoridate-hydrolyzing enzyme (DFPase) within mouse red blood cells. These erythrocytes thereby gain the ability to rapidly hydrolyze alkylphosphate cholinesterase (ChE) inhibitors such as diisopropyl fluorophosphate (DFP). DFPase rapidly hydrolyzes DFP to diisopropyl phosphate. Resealed erythrocytes provide a stable carrier system that can preserve the activity of encapsulated enzymes against otherwise rapid in vivo degradation; thus, ChE inhibitors can be degraded to relatively nontoxic metabolites by these erythrocyte carriers. Squid DFPase was purified from the hepatopancreas of Atlantic squid and DFPase activity was determined by measuring changes in fluoride ion concentration using a fluoride ion selective electrode. Mouse erythrocytes in suspension with excess squid DFPase were dialyzed against hypotonic buffer to allow the encapsulation of the enzyme to occur. Cells were then resealed by returning the suspension to isosmotic with saline. Rate of DFP hydrolysis observed with these cells was much greater than the rate of nonenzymatic hydrolysis and was directly proportional to the amount of the erythrocyte suspension added to the assay solution. The rate of hydrolysis was first order in substrate. Erythrocyte controls showed no endogenous DFPase activity. These results suggest that enzyme entrapment may be developed as a method to prevent and antagonize organophosphate poisoning.

Antagonism of the lethal effects of cyanide with resealed erythrocytes containing rhodanese and thiosulfate

A new concept has been presented for the antagonism of cyanide and possibly other chemical toxicants. Until now, only a half dozen truly specific "antidotes" were known. There are many other "antidotes" which merely prevent the absorption or enhance the elimination of a toxic compound rather than specifically destroying the substance to prevent its toxic effect. This new approach has considerable conceptual significance in toxicology, as it suggests the encapsulating other enzymes to degrade various other chemical toxicants. There are many chemical toxicants for which there are no specific antidotes, and the conceptual approach of employing erythrocyte-encapsulated enzyme provides an innovative, specific approach to antagonize the toxic and lethal effects of these chemicals.