Comparison of the genetic knowledge among nurses, students, and general public after ten years of implementation of genetic health program in Taiwan

This study aims to explore the genetic knowledge of different health professional, and non-professional populations after ten years of implementation of genetic health program in Taiwan. A self-administered questionnaire was developed to test the genetic knowledge of 885 respondent who included 361 community health nurses, 74 maternal-child nurses, 364 college students, and 86 members of the general public. The questionnaire included 33 questions which were divided into 4 categories (1) basic genetic knowledge, (2) Mendel's Law and probability, (3) prenatal diagnosis, (4) identification of common genetic disorders. The responses were scored and analyzed statistically with ANOVA tests. Community health nurses had the highest scores of genetic knowledge. However, they need more practice in the application of Mendel's Law and probability. Maternal-child nurses should be involved in genetic education programs and improve their ability to identify common genetic disorders and thus increase their ability to identify cases and provide better information to patients and families. Compared to other groups, college students had lower scores in prenatal diagnosis and identification of common genetic disorders. Therefore, college curricula in genetics need to emphasize more on these subjects. From the study, it was concluded that community health nurses are effective and competent to continue the genetic education as supported by the government in the past ten years. Maternal-child nurses are inevitably involved in genetic service, and they should be provided with suitable continuing education programs. The general public should strengthen their knowledge of prenatal diagnosis and common genetic disorders. Prenatal diagnosis should be added in the school curriculum of college students to expand their knowledge. New genetic technology, such as DNA analysis, should be added in the content of genetic education programs.

Differences in factors influencing the familial aggregation of febrile convulsion in population and hospital patients

Socio-demographic data, initial clinical manifestations, outcome and family aggregation of febrile convulsion (FC) were compared between 85 population and 364 multicenter patients. More patients presented with clustering of seizures and had recurrence of FC in multicenter group than in population group. Multicenter patients had more fever episodes per year, more day-card attendance and a higher incidence of FC history in their parents. The odds ratio of FC in the siblings was 6:1 in population group and 12:1 in multicenter group. Lower socioeconomic status influenced the presence of FC in the sibling of population group. Instead, FC histories in the father and paternal cousins of probands had influence on the presence of FC in the siblings of multicenter group. We conclude that the population FC sample rather than the hospital sample is the more representative. And there are differences not only in the clinical manifestations but also in the effect of environmental and genetic influences on the family aggregation in population and hospital patients.

Arachidonate and docosahexaenoate added to infant formula influence fatty acid composition and subsequent eicosanoid production in neonatal pigs

As natural components of human milk, arachdonic and docosahexaenoic acids play important roles in neonatal development; thus, addition of these fatty acids to infant formula has been suggested. This study examined the effects of supplementation of infant formula with microbial sources of either arachidonate or docosahexaenoate or both on accretion of these fatty acids in phospholipids and subsequent modulation of eicosanoid production in neonatal pig lung. One-day-old piglets received for 25 d one of four diets (n = 5): 1) standard diet containing a fat blend similar to that of conventional infant formula, 2) diet containing 0.9 g/100 g of total fatty acids as arachidonate, 3) diet containing 0.7 g/100 g as docosahexaenoate, or 4) a diet containing both 1.0 g/100 g as arachidonate and 0.8 g/100 g as docosahexaenoate. Arachidonate supplementation resulted in 30-60% significantly greater arachidonate in lung phosphatidylethanolamine and phosphatidylcholine. In phosphatidylinositol, however, arachidonate was resistant to dietary manipulation. Accretion of docosahexaenoate in all three phospholipid classes was 2.6- to 4.7-fold greater in docosahexaenoate-supplemented groups than in the standard group. Inclusion of arachidonate in the diet augmented both prostacyclin and thromboxane production by 25 to 35%. Docosahexaenoate supplementation resulted in the least eicosanoid production among the treatments, and significant suppression was observed for thromboxane when supplementation with both fatty acids was compared with supplementation with arachidonate alone. Thus, dietary arachidonic acid and docosahexaenoic acid at concentrations only slightly greater than those found in human milk tended to exercise opposing effects on lung eicosanoid production.

[The relationship between cell proliferation activity and secretory activity in pituitary adenoma--a review of 63 cases]

Determination of the cell proliferation activity of neoplasm is useful in making a prognosis. Immunohistochemical detection using MIB-1 monoclonal antibody has recently allowed us to assess tumor cell proliferation easily, because it can be performed on paraffin-embedded specimens and the results have been demonstrated to be positively correlated with the results of PCNA staining. In this study, surgical specimens of 63 pituitary adenomas were examined by immunohistochemical staining with MIB-1 monoclonal antibody. Twenty-nine cases were non-functioning pituitary adenomas, 20 were prolactin (PRL)-producing pituitary adenomas, and 14 were growth hormone (GH)-producing pituitary adenomas. The MIB-1 positive rates of the pituitary adenomas ranged from 0% to 6.46%. In the non-functioning pituitary adenomas, the MIB-1 positive rates ranged from 0% to 4.55% (mean : 0.76%), in the PRL-producing pituitary adenomas the MIB-1 positive rates ranged 0% to 6.46% (mean : 0.91%), and in the GH-producing pituitary adenomas the MIB-1 positive rates ranged 0% to 1.28% (mean: 0.58%). There were no significant differences between these values according to the results of the Wilcoxon signed-rank test. Although the size of the non-functioning pituitary adenomas was not correlated with their MIB-1 positive rate, tumor size was closely correlated with the interval between the onset of the initial symptoms and the date of surgery. In the PRL-producing pituitary adenomas, the MIB-1 positive rate was not correlated with serum PRL levels as an index of secretory activity, but was correlated with the PRL staining positive rate. Preoperative bromocriptine therapy proved effective in reducing tumor size and serum PRL levels, but had no effect on the MIB-1 positive rate. In the GH-producing pituitary adenomas, the MIB-1 positive rate was not correlated with serum GH levels as an index of secretory activity, but was closely correlated with the GH staining positive rate. All three groups included both invasive and noninvasive tumor types, but there were no close statistical correlations between the three tumor types.

A clinico-immunohistochemical study of giant cell glioblastoma

We have reported 7 cases of giant cell glioblastoma. All cases died within 14 months despite aggressive treatment. By immunohistochemical staining, lymphocyte infiltration was found in 6 cases. GFAP and vimentin stained positive in all cases. The MIB-1 positive rate was 13.8-90% (average, 34.9%); small and mononucleated giant cells stained more than multinucleated and monstrous cells. It was concluded that this tumor can be highly malignant and its degree of malignancy is determined by the biological behavior of the mononucleated giant cells and small cells.

A follow-up study of genetic counseling in Down syndrome

To ascertain the effects of genetic counseling on the education of counselees, a questionnaire study on the acceptance of genetic knowledge was carried out among 126 parents of children with Down syndrome. Those parents from the "Down Syndrome Association" had best scores for knowledge, followed by those who had received counseling according to a designed format (programmed counseling) in this Hospital. Parental perceptions of the information needed in genetic counseling were also studied and it was found that most parents thought that the topics of education and medical care were more important than genetic information. Realization of such difference in primary concern between counselors and counselees may improve the effectiveness of genetic counseling.

Expression of human lysozyme mRNA in the mammary gland of transgenic mice

Owing to its inherent antimicrobial effect and positive charge, the expression of human lysozyme in bovine milk could be beneficial by altering the overall microbial level and the functional and physical properties of the milk. We have used transgenic mice as model systems to evaluate the expression of human lysozyme containing fusion gene constructs in the mammary gland. Expression of human lysozyme was targeted to the mammary gland by using the 5' promoter elements of either the bovine beta (line B mice) or alpha s1 (line H mice) casein genes coupled to the cDNA for human lysozyme. Expression of human lysozyme mRNA was not found in mammary tissue from any of line B mice. Tissues were analysed from six lines of H mice and two, H6 and H5, were found to express human lysozyme mRNA in the mammary gland at 42% and 116%, respectively, of the levels of the endogenous mouse whey acidic protein gene. At peak lactation, female mice homozygous for the H5 and H6 transgene have approximately twice the amount of mRNA encoding human lysozyme as hemizygous animals. Expression levels of human lysozyme mRNA in the mammary gland at time points representing late pregnancy, early, peak and late lactation corresponded to the profile of casein gene expression. Human lysozyme mRNA expression was not observed in transgenic males, virgin females or in the kidney, liver, spleen or brain of lactating females. A very low level of expression of human lysozyme mRNA was observed in the salivary gland of line H5.

Diverse applications of continuous lumbar drainage of cerebrospinal fluid in neurosurgical patients

From 1984 to 1991, continuous lumbar drainage (CLD) of cerebrospinal fluid (CSF) had been applied in 48 neurosurgical patients. Eleven of them had CSF accumulation and/or leakage at the operative sites and 37 of them suffered from CSF rhinorrhea. Successful treatment was achieved in 98% (47/48) of patients. There was neither death nor infection noted in this series. Complication was found in only one patient who developed acute subdural haematoma with pneumocephalus six days after CLD. After emergency craniotomy and evacuation of haematoma, the patient recovered without neurological deficit. The results suggest that CLD is a simple, safe and effective method in the treatment of CSF accumulation and/or leakage at the operative sites, as well as CSF rhinorrhea of various aetiologies.

Genomic organization of the human procollagen alpha 1(II) collagen gene

The nucleotide sequence of the human procollagen alpha 1(II) collagen gene extending from within the first intron through exon 15, and part of the 15th intron has been determined. This sequence analysis (7056 bases) identifies the intron/exon organization of the region of this gene encoding the N-propeptide and part of the triple-helical domain. Structural comparison of this with the genes of other human fibrillar collagens shows considerable diversity in terms of size and number of introns and exons that encodes the N-propeptide domain. Although the genomic structure of the human procollagen alpha 1(II) gene is quite different from the rat procollagen alpha 1(II) gene, the nucleotide coding sequences are 89% identical.

Study of normal and cancerous urine using photoacoustic spectroscopy

Photoacoustic spectroscopy (PAS) is a valuable technique, increasingly applied in clinical and biological analysis. Light absorption properties of urine and body tissue can be obtained more easily by the PAS technique because of its high sensitivity, than by the conventional optical techniques. By observing their absorption properties it is possible to diagnose some diseases and in this study we have used PAS to assess cancerous changes in urine and tissue. Three groups were studied: normal individuals; patients with cancer; and patients with cancer and subsequent inflammation; and the characteristic light absorption peaks obtained for a certain band (240-420 nm). These results were compared with the clinical diagnosis and proved consistent and reliable for the diagnosis of urinary tract cancer subsequently confirmed by operation. This method will probably be a useful tool for the early clinical diagnosis of cancer of the urinary system.

Comparison and accuracy of methodologies employed for analysis of hydropathy, flexibility and secondary structure of proteins

Various methods have been developed recently for predicting antigenic determinants in a protein by analyzing its hydropathicity, flexibility or secondary structure. The predicted results by these methods were compared directly to the observed structure of the proteins to determine how accurate they were. Regression and correlation of the predicted hydropathicity versus the observed solvent accessibility and the predicted chain flexibility versus actual mobility were determined. Three separate methods of hydropathic analysis had correlation coefficients of 0.52, 0.63 and 0.57 respectively, while a published method for chain flexibility analysis had a 0.19 correlation coefficient. Similarly, agreement between the observed and the predicted secondary structures by two methods was also determined. The limitations of these techniques were clearly defined.

Primary mediastinal seminoma

Primary mediastinal seminoma is a rare neoplastic disease. Only 133 cases have been reported in the literature. Five patients with primary mediastinal seminoma had been treated at VGH from 1974 to 1986. All of them received exploratory thoracotomy but only two of them were resectable. Postoperative radiation therapy was given regardless of resection. One had additional chemotherapy due to nodal involvement. All five patients showed complete resolution and were alive and free of disease for an average follow-up period of 42.6 months (range, 5-82 months). So we conclude that mediastinal seminoma is a rare neoplastic disease and can be treated primarily by surgery. Irradiation can also induce complete remission and long term survival in those with unresectable tumors.

Cytogenetical analysis of the germ cell in the domestic drake and mule drake

Experiments were conducted to study the germ cell of testes in the domestic drake (Tsaiya drake) and the mule drake. The histological sections of testes of both drakes were compared in this study. The results showed that rapid testicular growth did not occur until 7 weeks of age in domestic drakes and 15 weeks of age in the mule drakes. The rate of growth of the testes and the increase in the ratio of testes weight to body weight in domestic drakes at different ages were much more rapid than in the mule drakes. However, the opposite results were found in the body weights. In the mule drakes, spermatogonia and primary spermatocytes could be observed in the seminiferous tubules, but no secondary spermatocytes, spermatids or spermatozoa in seminiferous tubules were found up to 52 weeks of age. This showed that the meiotic division had not occurred in the mule drakes. In the domestic drakes, spermatogonia in the seminiferous tubules were observed at 1 week of age. Primary spermatocytes of some males appeared as early as the third week of age. Secondary spermatocytes and spermatids in the seminiferous tubules of some drakes began to appear at 5 weeks of age as a result of the meiotic division of the spermatocytes. At 7 weeks of age, spermatids were in process of metamorphosis, and spermatozoa were first observed in the seminiferous tubules of the drake. All testes of drakes 9 weeks of age contained spermatozoa. The percentage of the seminiferous tubules containing spermatozoa increased gradually with age, and approached a plateau at 15 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of cytotoxicity of 2-chloro-2'-deoxyadenosine and 2-bromo-2'-deoxyadenosine on cell growth, clonogenicity, DNA synthesis, and cell cycle kinetics

The cytotoxic effects of the adenosine deaminase resistant analogues 2-bromo-2'-deoxyadenosine (2-BrdAdo) and 2-chloro-2'-deoxyadenosine (2-CldAdo) have been compared with those of deoxyadenosine (dAdo). Like 2-CldAdo, 2-BrdAdo is highly effective in inhibiting the growth of many T-lymphoblastoid, B-lymphoblastoid, and myeloid cell lines in culture. Concentrations required to inhibit growth of CCRF-CEM human T-lymphoblastoid cells by 50% (IC50) are: 2-CldAdo, 0.045 microM; 2-BrdAdo, 0.068 microM; dAdo, 0.9 microM in the presence of 5 microM erythro-9-(2-hydroxy-3-nonyl)adenine. Like dAdo, 2-BrdAdo causes a much greater decrease in DNA synthesis than in RNA and protein synthesis. For each of the nucleosides the concentration required to cause 50% inhibition of DNA synthesis (as measured by thymidine incorporation) in an 18-h exposure is very similar to the IC50 for growth and to the concentration required to decrease viability (clonogenicity) over 18 h by 50% (EC50). A fraction of CCRF-CEM cells (approximately equal to 30%) is resistant to killing by exposure to 2-BrdAdo or 2-CldAdo for 4 h at concentrations 100 times the EC50, but 3% of cells are resistant to exposure for 4 h to a concentration of dAdo 3 times the EC50. Each of the three nucleosides causes accumulation of cells in S phase, the accumulation becoming more marked with longer periods of exposure and with higher concentrations of nucleoside. During exposures for 18-24 h at a concentration of nucleoside near the EC50 most cells accumulate in S, with most in early S, whereas exposure to concentrations greater than EC95 accumulates cells at the G1/S border. This suggests that loss of viability is associated with a blockade of some process specifically occurring at the initiation of S phase. At an optimum dosage schedule, 2-BrdAdo and 2-CldAdo have similar therapeutic effects against L1210 in vivo, both producing over 99% cell kill, but the optimum dosage of 2-CldAdo is lower.

Genetic analysis of low lambda 1 chain production in mice

Several commonly used strains of laboratory mice from Charles River Laboratories were found to produce extremely low or undetectable levels of serum immunoglobulins bearing lambda 1 light chain (lambda 1 Ig). Individual CF-1, CD-1, and CFW random-bred mice were tested for serum lambda 1 levels, lambda 1-specific anti-NP responses, and genomic polymorphisms at the lambda 1 locus. In all cases, a complete correlation among these parameters was observed. The results indicated that nearly all CFW, greater than 70% of CD-1 but none of the CF-1 mice produced low levels of lambda 1 light chain. The low lambda 1 Ig production is due to a genetic defect either similar or identical to that observed in SJL mice. The data suggest that the lambda 1 locus of CD-1, CFW, and SJL mice are derived from a common ancestor. We also surveyed lambda 1 Ig production in a series of wild mice. Mice producing low lambda 1 Ig were frequently observed. The wild mice with low lambda 1 Ig levels were captured in diverse geographic areas, including Europe, Middle East, Asia, and South America. Preliminary study suggests that the defect in the wild mice is different from that of SJL, CD-1, or CFW mice and implies that other mechanisms regulate lambda 1 Ig production in wild mice.

Genetic analysis of low lambda 1 chain production in mice

Several commonly used strains of laboratory mice from Charles River Laboratories were found to produce extremely low or undetectable levels of serum immunoglobulins bearing lambda 1 light chain (lambda 1 Ig). Individual CF-1, CD-1, and CFW random-bred mice were tested for serum lambda 1 levels, lambda 1-specific anti-NP responses, and genomic polymorphisms at the lambda 1 locus. In all cases, a complete correlation among these parameters was observed. The results indicated that nearly all CFW, greater than 70% of CD-1 but none of the CF-1 mice produced low levels of lambda 1 light chain. The low lambda 1 Ig production is due to a genetic defect either similar or identical to that observed in SJL mice. The data suggest that the lambda 1 locus of CD-1, CFW, and SJL mice are derived from a common ancestor. We also surveyed lambda 1 Ig production in a series of wild mice. Mice producing low lambda 1 Ig were frequently observed. The wild mice with low lambda 1 Ig levels were captured in diverse geographic areas, including Europe, Middle East, Asia, and South America. Preliminary study suggests that the defect in the wild mice is different from that of SJL, CD-1, or CFW mice and implies that other mechanisms regulate lambda 1 Ig production in wild mice.

Improved synthesis and antitumor activity of 2-bromo-2'-deoxyadenosine

A more convenient synthetic route to 2-bromo-2'-deoxyadenosine (5) is reported, and results indicating significant antitumor activity of 5 against three murine tumors (L1210 leukemia, B16 melanoma, and M5076 ovarian carcinoma) are presented. The antitumor activity is very schedule dependent, being much greater when the drug is given q 3 h (X8) every 3rd or 4th day than when given by single daily administration. Toxicity of 5 for the tumor-bearing host is also very schedule dependent. Thus, on the q 3 h schedule of administration, a greater cumulative dose is tolerated by the host, and the therapeutic effectiveness of 5 is enhanced accordingly.

Formation of 3-(2'-deoxyribofuranosyl) and 9-(2'-deoxyribofuranosyl) nucleosides of 8-substituted purines by nucleoside deoxyribosyltransferase

Earlier results suggested that although the N-deoxyribosyltransferase from lactobacilli is a convenient tool for the preparation of analogs of 2'-deoxyadenosine, 8-substituted purines do not act as substrates. However, eight of nine 8-substituted purines that were examined proved to be substrates for the transferase from Lactobacillus leichmannii, and deoxyribonucleosides of four of these bases have been prepared. The substituents at C-8 of the purine greatly affect the rate of deoxyribosyl transfer to the base, and in all cases the rate is slower than transfer to purines lacking an 8-substituent. The 8-substituent also affects the nature of the nucleoside formed. With the electron-donating methyl group at position 8 of adenine, the transferase forms the expected 8-methyl-9-(2'-deoxyribofuranosyl)adenine. However, when purines bearing an electron-withdrawing substituent at the 8-position are used as substrates, the deoxyribosyl moiety is preferentially transferred to N-3 of the base. In the case of 8-trifluoromethyladenine the 3-deoxyribonucleoside is the only product detectable. With 8-bromo or 8-chloroadenine as substrate the 3- and 9-deoxyribonucleosides can both be isolated from the enzymatic reaction mixture. Time course studies indicated that with thymidine and 8-bromoadenine as substrates the 3-deoxyribonucleoside is initially the major product, but that the 9-deoxyribonucleoside becomes the major product after long incubation periods. Negligible interconversion of these nucleosides occurs in the absence of transferase, but conversion in either direction occurs readily in the presence of the enzyme. Significant hydrolysis of pyrimidine and purine deoxyribonucleosides occurs in the presence of the transferase. This was more obvious during the course of reactions involving 8-substituted purines because the slowness of deoxyribosyl transfer required longer incubation periods and larger amounts of enzyme. The hydrolysis is proportional to enzyme concentration, little affected by the nature of the base and is attributed to hydrolysis of a deoxyribosyl derivative of the transferase which is an obligatory intermediate of deoxyribosyl transfer. 8-Trifluoromethyl-3-(2'-deoxyribofuranosyl)adenine, 8-methyl-9-(2'-deoxyribofuranosyl)adenine, and 8-bromo-9-(2'-deoxyribofuranosyl)adenine were tested for their ability to inhibit the growth of CCRF-CEM cells in culture. Unlike the potent 2-halogeno-2'-deoxyadenosine derivatives, these three nucleosides cause less than 50% inhibition at concentrations up to 100 microM.

Mechanism of action of cobra cardiotoxin in the skeletal muscle

Cobra cardiotoxin (CTX) is a potent polypeptide in inducing irreversible contracture of the chick biventer cervicis muscle. this polypeptide is about 2000 times more potent than caffeine in inducing contracture of this muscle preparation but the rate of CTX contracture is slower. Studies on the interaction on CTX with divalent cations showed that low Ca0++ (10(-31-2 mM)-Krebs' enhanced markedly while ethylene glycol bis (beta-aminoethyl ether)-N,N'-tetraacetic acid-Krebs' or high Ca++ (12 mM) inhibited completely CTX contracture; 10 mM Mg++ enhanced but 20 mM Mg++ or 10 mM Zn++ inhibited CTX contracture. Neither Na+ nor tetrodotoxin affected CTX contracture. Comparison of CTX and caffeine contracture showed that ethylenediamine tetraacetic acid (1 mM) and Mn++ (5 mM) inhibited CTX contracture completely but inhibited caffeine contracture only partially; procaine did not inhibit CTX contracture but inhibited caffeine contracture competitively; by contrast, N-ethylmaleimide inhibited CTX but not caffeine contracture. Neither caffeine nor K+ contracture was inhibited by 12 mM Ca++. CTX could induce contracture in the depolarized muscle and the muscle with T-tubule destroyed or closed, whereas K+ failed to induce contracture in the latter. Caffeine contracture was inhibited in the muscle with a previous elicitation of CTX contracture. This antagonistic effect of CTX could be prevented by calcium. Moreover, CTX increased both 45Ca++ efflux and 45Ca++ uptake. Both Zn++ (0.6 mM) and Mg++ (10 mM) but not protamine and polylysine mimicked CTX to increase 45 Ca++ uptake. Zn++ (0.6mM) was also found to be effective in replacing Ca0++ to induce CTX contracture in 10(-6) M Ca0++. CTX increased Ca and Na but decreased K contents of the muscle. The binding of radioactive iodinated CTX was inhibited not only by unlabeled CTX but also by 10mM Ca++. All of these findings suggest that CTX may affect a membrane calcium binding site and may induce contracture by releasing the membrane calcium rather than by increasing Na+ permeability of the muscle membrane.

Effects of chronic treatment with various neuromuscular blocking agents on the number and distribution of acetylcholine receptors in the rat diaphragm

1. Acetylcholine receptors in the end-plate and non-end-plate areas of the rat diaphragm, after treating the animal with hemicholinium-3, alpha- or beta-bungarotoxin in vivo, were studied by their specific binding of labelled alpha-bungarotoxin. 2. Subcutaneous injection of maximum tolerable doses of hemicholinium-3 (50 mug/kg) twice daily for 7 days increased the number of extrajunctional receptors along the whole length of muscle fibre, the approximate density of receptor on muscle membrane being increased from 6/mum2 in normal diaphragm to 38/mum2. Junctional receptors were also increased in number from 2-2 x 10(7) to 2-8 x 10(7) per end-plate. 3. Five days after denervation, there were approximately 153/mum2 extrajunctional receptors and the number of receptors on the end-plate was increased by 220%. 4. Intrathoracic injection of beta-bungarotoxin (50 mug/kg) also increased the density of extrajunctional receptors to approximately 104/mum2, and the number of end-plate receptors by 140% in 5 days. The neuromuscular block was extensive and prolonged. 5. [3H]Diacetyl alpha-bungarotoxin (150 mug/kg) injected into thoracic cavity caused complete neuromuscular blockade for 12 hr. At 24 hr, the synaptic transmission was restored in 80% of the junctions with less than 10% end-plate receptors freed, whereas the safety factor for transmission in normal diaphragm was 3-5. Extrajunctional receptors appeared to increase within 24 hr. This increase continued despite the restoration of neuromuscular transmission, and the receptor density at 5 days was approximately 5l/mum2. The number of junctional receptors, however, was not increased. Repeated injection of the toxin gave the same result. 6. It is concluded that the numbers of junctional and extrajunctional acetylcholine receptors are regulated in different ways, and the possible role of acetylcholine is discussed.

Comparative studies on the biological activities of cardiotoxin, melittin and prymnesin

The actions of cardiotoxin (CTX), melittin and prymnesin were compared on dog erythrocytes, chicken biventer cervicis muscle, rabbit conjunctiva, acetylcholinesterase, succinate-cytochrome c reductase and turbidity of the rat liver mitochondrial suspension. 1. CTX and melittin were approximately equipotent in the various biological activities, while prymnesin was not. 2. The rate of direct ehmolysis induced by CTX was slow, while that induced by either melittin or prymnesin was fast. 3. Phosphate ions, 10mM Ca++, as well as 1 mM reduced glutathione, considerably inhibited the CTX-induced hemolysis, but only slightly inhibited that induced by melittin or prymnesin. 4. CTX, melittin and prymnesin caused contracture of the chicken biventer cervicis muscle. Prymnesin was much less active in this preparation as compared with its hemolytic potency. The CTX contracture was completely inhibited by high Ca++ (10mM) medium, while the melittin contracture was not. 5. The rate of CTX contracture to reach the peak tension was increased when the concentration of CTX was increased, while the rate of melittin contracture did not change very much as the concentrations varied. 6. All three toxins caused a local irritation of the conjunctival sac of the rabbit eye. 7. Both CTX and melittin inhibited acetylcholinesterase and succinate-cytochrome c reductase activities, and also increased the turbidity of the rat liver mitochondrial suspension, while prymnesin was totally inactive in these respects. It is concluded that the mechanism of actions of these toxins may be different at the molecular level. The role of the detergent properties of these toxins in their biological activities is discussed.