Point mutation of the neu gene in rat neural tumor RT4-AC cells: suppression of tumorigenicity by s-Myc

Forced expression of the s-myc gene suppressed the tumorigenicity of rat RT4-AC tumor cells in nude mice, as reported previously. Polymerase chain reaction (PCR) analysis indicated that RT4-AC cells established from a tumor of the peripheral nervous system contain an activated neu gene with a T----A transversion in the transmembrane domain. Synthesis of a protein of 60 kd kd in RT4-AC cells was specifically inhibited by expression of the s-myc gene. These results strongly suggest that s-Myc suppresses the transforming activity of rat neural cells transformed by expression of the activated neu gene, and plays an important role in regulating expression of a cellular gene contributing to cell transformation, such as the gene that encodes the p60 protein.

Leukotriene D4 excitation of rabbit distal colon arises in the region of the muscularis mucosae

We previously have demonstrated in vivo that intra-arterial administration of leukotriene D4 (LTD4) causes increased myoelectric and mechanical activity in the rabbit distal colon. The aim of this study was to use both in vivo and in vitro techniques to try to elucidate the mechanism underlying this effect. In vivo the excitatory response of the rabbit distal colon to LTD4 was abolished by pretreatment with atropine (0.1 mg/kg iv) or hexamethonium (5 mg/kg iv) or the LTD4 receptor antagonist SK&F 102922 (0.8 micrograms/kg ia). In vitro neither the longitudinal nor the circular muscle layer responded to LTD4 (10(-10) to 10(-7) M) with a contractile response. Over the same concentration range, LTD4 caused contractions of the muscularis mucosae that were attenuated by either SK&F 102922 (10(-9) to 10(-7) M) or indomethacin (10(-6) M) but were unaffected by atropine (10(-6) M), pyrilamine (10(-6) M), or tetrodotoxin (10(-6) M). Full thickness segments of longitudinal muscle, circular muscle, and muscularis mucosae did not contract to LTD4. These data imply that LTD4-induced excitation of the rabbit distal colon in vivo arises as a result of the excitation of LTD4 receptors in the region of the muscularis mucosae and that this leads ultimately to the release of acetylcholine onto the muscularis propria. It is proposed that one possible mechanism leading to the latter effect is an increased excitability of intrinsic nerves resulting from a prostaglandin-induced depression of norepinephrine release from nerves impinging on the submucosal plexus.

Pulsatile pressure and flow in the skeletal muscle microcirculation

Although blood flow in the microcirculation of the rat skeletal muscle has negligible inertia forces with very low Reynolds number and Womersley parameter, time-dependent pressure and flow variations can be observed. Such phenomena include, for example, arterial flow overshoot following a step arterial pressure, a gradual arterial pressure reduction for a step flow, or hysteresis between pressure and flow when a pulsatile pressure is applied. Arterial and venous flows do not follow the same time course during such transients. A theoretical analysis is presented for these phenomena using a microvessel with distensible viscoelastic walls and purely viscous flow subject to time variant arterial pressures. The results indicate that the vessel distensibility plays an important role in such time-dependent microvascular flow and the effects are of central physiological importance during normal muscle perfusion. In-vivo whole organ pressure-flow data in the dilated rat gracilis muscle agree in the time course with the theoretical predictions. Hemodynamic impedances of the skeletal muscle microcirculation are investigated for small arterial and venous pressure amplitudes superimposed on an initial steady flow and pressure drop along the vessel.

[Community-based epidemiological study on hypertension and diabetes--community-based preventive medicine by Yang-Ming Crusade in 1989]

A community-based preventive medicine project was carried out by the Yang-Ming Crusade, organized by more than 180 students of National Yang-Ming Medical College, in July 1989. All of the registered residents over 40 years old of 13 villages (from 8 towns) were chosen for the study population. Their blood pressure, urine sugar, urine protein, high and weight were taken by the crusaders through door by door interviews. The screening positive cases were referred to the local Group Practice Center for confirm diagnosis and follow-up treatment. Among 7598 study population. 5088 (67%) were interviewed including male 48.9% and female 51.0%. About one third of the interviewee were in 50-59 age group. 762 hypertensive cases out of 3462 interviewee with blood pressure taken were found. The prevalence of hypertension was 21.0%. 334 diabetes cases out of 4713 interviewee with urine sugar taken were found. The prevalence of diabetes was 7.1%. Among 762 hypertensive cases, 560 (77.1%) were self-recognized and treated with the following methods: modern medicine 79.2%, traditional medicine 8.7%, drug stores 6.4%, and herbs 2.8%. Among 334 diabetes cases, 203 (60.8%) were self-recognized and only 171 (51.2%) were treated with the following methods: modern medicine 79.5%, traditional medicine 8.2%, drug stores 3.5%, and herbs 4.1%. Univariate analysis on hypertension showed that age, ethnicity, obesity, diabetes, hypertension history of mother, and hypertension history of siblings were significant variables. All of the above 6 variables were significant in multiple logistic regression analysis. Univariate analysis on diabetes showed that age, ethnicity, obesity, hypertension, diabetes history of father, diabetes history of mother, and diabetes history of siblings were significant variables. However only 4 variables, age, hypertension, diabetes history of mother, and diabetes history of siblings, were significant in multiple logistic regression analysis.

[A study on third-trimester gravidas' knowledge of infant care activity]

The purpose of this study was to measure the degree of gravidas' knowledge of infant care activity, and to identify the factors influencing the difference of gravidas' knowledge. The subjects of this study consisted of 159 gravida visited 2 general hospitals, 2 OB/GY clinics and 2 midwives' clinics in J city for antenatal care. The data were collected from December 1 to 30, 1989. The instrument used for this study was true false type question which was developed by investigator through literature review. Data were analyzed by percentage, mean, t-test and ANOVA on significant difference with SPSS program. The results of this study were summarized as follow: 1) The degree of gravidas' knowledge of infant care activity was 36.75, the degree of gravidas' knowledge of physical care activity was 16.70, and the degree of gravidas' knowledge of psychosocial care activity was 20.05. 2) Among the physical care activity knowledge items, the diaper should be changed whenever it is soiled, shortly after feeding is over, bathing is bad, gently patted or stroked on the back when bubbling, 10 minutes time in bathing is appropriate, infant is crying whenever he is hungry per 3-4 hours, and room humidity controlled 60 percent, more or less were over a percentage of 80 of right answer. Among the physical care activity knowledge items, a reason for burping was the air he has swallowed will rise to the top of his stomach and be eructated, burping is advisable after the feeding, dressing of umbilical area is not necessary, the thermometer should not be boiled for disinfection, it is important that the infant grasp the whole nipple within his mouth, using alcohol sponge is bad whenever diaper is soiled, and when temperature is taken by the rectal method, infant legs should be grasped firmly were less than a percentage of 60 of right answer.(ABSTRACT TRUNCATED AT 400 WORDS)

Mathematics achievement of children in China and the United States

First and fifth graders in Beijing and Chicago were given a battery of mathematics test. Whether tested with problems requiring solely computation or with ones requiring application of knowledge about mathematics, American children's performance was consistently inferior to that of Chinese children. Interviews with American children suggested that they like mathematics, believe they are doing well in mathematics, and do not perceive mathematics as a difficult subject. American children's poor performance appears to be attributable, in part, to low motivation for devoting more attention to mathematics. Low standards held by American parents for academic achievement and lower interest in teaching mathematics by American teachers appear to contribute to American children's poor performance.

Effect of intercalating dyes on the production of antibiotics by Micromonospora rosaria and Micromonospora purpurea

The effect of treatment with various intercalating dyes on the ability to produce antibiotics in Micromonospora rosaria and Micromonospora purpurea was studied. Treatment with acriflavine resulted in a high frequency loss of antibiotic productivity in both species. In M. rosaria, the loss of antibiotic-producing ability appeared to be strain-dependent. In M. purpurea, up to 90% of colonies were found to have lost gentamicin-producing ability when protoplasts were used in the test. These antibiotic-nonproducing strains were further studied. The following observations were made: (1) Unlike the producing ability, the resistance to the antibiotics is a very stable character in both species. (2) Protoplast fusion analysis indicates that rosamicin-nonproducing characteristics of MR 217-AF2 and MR 217-AF3 strains induced by the acriflavine treatment is due to chromosomal mutation or rearrangement but not to loss of a plasmid. (3) Gentamicin-nonproducing strains of M. purpurea responded differently to the supplementation of streptamine or DOS in the culture medium. When supplemented with streptamine or DOS, some of these strains regained the ability to produce antibiotic, showing that the biosynthesis of intermediate was affected in these strains.

Tellurium-induced neuropathy: a model for reversible reductions in myelin protein gene expression

Inclusion of 1.1% tellurium in the diet of developing rats causes a highly synchronous primary demyelination of peripheral nerves, which is followed closely by a period of rapid remyelination. The demyelination is related to the inhibition of squalene epoxidase activity, which results in a block in cholesterol synthesis and accumulation of squalene. We now report that the demyelination resulting from this limiting of the supply of an intrinsic component of myelin (cholesterol) leads to repression of the expression of mRNA for myelin-specific proteins. Tellurium exposure resulted in an increase in total RNA (largely rRNA) in sciatic nerve, which could not be accounted for by cellular proliferation; these increased levels of rRNA may be a reactive response of Schwann cells to toxic insult and may relate to the higher levels of protein synthesis required during remyelination. In contrast, steady-state levels of mRNA, determined by Northern blot analysis, for P0 and myelin basic protein were markedly decreased (levels after 5 days of tellurium exposure were only 10-15% of control levels as a fraction of total RNA and 25-35% of control levels when the increased levels of total RNA were taken into account). Message levels increased during the subsequent period of remyelination and reached near-normal levels 30 days after beginning tellurium exposure. Although message levels for the myelin-associated glycoprotein showed a similar temporal pattern, levels did not decrease as greatly and subsequently increased sooner than did levels for P0 and myelin basic protein. The coordinate alterations in message levels for myelin proteins indicate that Schwann cells can down-regulate and then up-regulate the synthesis of myelin in response to alterations in the supply of membrane components.

A case of adrenal lymphangiectatic cyst associated with severe hypertension

Adrenal lymphangiectatic cyst is a very rare pathological and clinical disease entity, and its clinical silence and lack of characteristic symptoms and signs makes it difficult to diagnose preoperatively. We experienced a case of adrenal lymphangiectatic cyst, accompanied by severe refractory hypertension, which was corrected by surgical removal of the cyst. We report it with a review of the literature.

Purification and properties of D-myo-inositol 1,4,5-trisphosphate 3-kinase from rat brain. Susceptibility to calpain

A new, rapid method for purification of inositol(1,4,5)P3 3-kinase in high yield from rat brain is described. Purified enzyme exhibited a polypeptide of Mr = 53,000 on sodium dodecyl sulfate-polyacrylamide gel and a specific activity of 29 mumol/min/mg at 37 degrees C in the absence of calmodulin. Inclusion of calpain inhibitors was critical for obtaining the 53-kDa protein as the major product and 0.1% of the zwitterionic detergent, 3-[(3-cholamidopropyl)dimethylamino]-2-propanesulfonate, was necessary to stabilize enzyme activity. In the absence of calpain inhibitors, the 53-kDa protein degraded progressively during purification and yielded a mixture containing polypeptides of various sizes. Relative intensity of these degradation products on sodium dodecyl sulfate-polyacrylamide gel varied from one preparation to another. However, broad band(s) at the 42-45 kDa region and a band at 35 kDa were always weak, while bands of 53, 51, 40 (sometimes doublets), 33, and 32 KDa were usually strong. The fact that all of these polypeptides including the weak bands of 42-45 and 35 kDa were derived from the 53 kDa form was confirmed by their immunocross-reactivity with monoclonal antibodies to the 53 kDa form. When the 51, 40, and a mixture of the 33 and 32 kDa forms were obtained separately and nearly free from other forms, each of them exhibited catalytic activity. Nevertheless, calmodulin binds to polypeptides larger than 35,000 but not to the 33 and 32 kDa forms. Incubation of the purified 53 kDa form with calpain generated a fragmentation pattern nearly identical to that generated during purification in the absence of calpain inhibitors. Incubation with five other endoproteases produced proteolytic fragments slightly different from those by calpain. However, the general fragmentation patterns generated by the proteases were similar, suggesting that inositol(1,4,5)P3 3-kinase contains several motifs susceptible to a variety of proteases.

Evaluation of thiol broth for the culture of Salmonella typhi and other bacteria from blood

Thiol broth is known to neutralize various antimicrobial agents. Positivity of growth of various species of bacteria from blood in thiol broth was reported as similar to that in tryptic soy broth (TSB). As blood cultures are often used for the diagnosis of typhoid fever, and as patients may receive antimicrobial therapy before blood culture, the positivity and rapidity of growth of Salmonella typhi in thiol broth were compared to those in TSB. Routine blood culture samples from Yonsei Medical Center patients were inoculated in 50-ml amounts of TSB and thiol broth. The media were prepared from dehydrated products and did not contain CO2, but TSB contained 0.025% sodium polyanethol sulfonate (SPS). Growth of S. paratyphi-A, Klebsiella pneumoniae, Enterobacter sp., Serratia marcescens and alpha-hemolytic Streptococcus were similar in both media. However, greater positivity and shorter incubation time for macroscopic detection were noted in TSB with S. typhi, Escherichia coli and Staphylococcus aureus. It is concluded that thiol broth is inferior to TSB plus SPS for the culture of S. typhi from blood.

Sexual transmission of hepatitis D virus infection in Taiwan

Multivariate analysis of the risk factors for hepatitis D virus infection among 53 men with acute hepatitis D virus superinfection, 59 men with acute exacerbation of chronic hepatitis B and 54 asymptomatic male hepatitis B carriers revealed that sexual contact with prostitutes and use of nondisposable needles were the factors significantly associated with hepatitis D virus infection in Taiwan (odds ratio = 5.5, 95% confidence interval = 3.3 to 9.2; odds ratio = 2.4, 95% confidence interval = 1.3 to 4.4, respectively). The prevalence of antibody to hepatitis D virus antigen among hepatitis B virus carriers with histories of sexual exposure to prostitutes was 10.3% (14 of 136) and the prevalence of hepatitis D virus antigen among the female prostitutes who were hepatitis B virus carriers was 59% (24 of 51). Among those who admitted to sexual contact with prostitutes, testing for hepatitis D virus antigen revealed positive correlations with the frequency of such sexual contacts and with the frequency of history of venereal diseases. Among the female prostitutes, the prevalence of hepatitis D virus antigen had a positive correlation with the frequency of sexual contact and a negative correlation with age. Analysis of serum hepatitis D virus RNA among those with hepatitis D virus antigen revealed that 4 of the 9 with sexual exposure to prostitutes and 3 of the 24 prostitutes were positive. From these findings, we conclude that these two groups are not only at high risk for hepatitis D virus infection but also form a reservoir of this virus.

Cardiovascular effects of mycelium extract of Ganoderma lucidum: inhibition of sympathetic outflow as a mechanism of its hypotensive action

In an effort to understand the mechanism of cardiovascular actions of Ganoderma lucidum which was cultivated in Korea, the mycelium was isolated for a large-scale culture. Water extract of the mycelia was evaluated for its cardiovascular activity in anesthetized rabbits and rats. The left femoral artery and vein were cannulated for the measurement of arterial pressure and subsequent delivery of drugs. The left kidney was exposed retroperitoneally and a branch of the renal nerve was used to integrate renal efferent or afferent nerve activities. The extract decreased systolic and diastolic blood pressure, which was accompanied by an inhibition of renal efferent sympathetic nerve activity. The extract did not decrease heart rate in these animals, although there was clear hypotension in the extract dose dependent manner. This suggests that the hypotension induced by the treatment of the extract was secondary to the primary effect of the extract in the central nerve system, which suppressed the sympathetic outflow. Therefore we concluded that the mechanism of hypotensive action of Ganoderma lucidum was due to its central inhibition of sympathetic nerve activity.

Molecular cloning and expression of a complementary DNA for inositol 1,4,5-trisphosphate 3-kinase

A complementary DNA (cDNA) clone that encodes inositol 1,4,5-trisphosphate 3-kinase was isolated from a rat brain cDNA expression library with the use of monoclonal antibodies. This clone had an open reading frame that would direct the synthesis of a protein consisting of 449 amino acids and with a molecular mass of 49,853 daltons. The putative protein revealed a potential calmodulin-binding site and six regions with amino acid compositions (PEST regions) common to proteins that are susceptible to calpain. Expression of the cDNA in COS cells resulted in an approximately 150-fold increase in inositol 1,4,5-trisphosphate 3-kinase activity of these cells.

Detection of human papillomavirus (HPV) DNA in laryngeal papilloma

Laryngeal papillomas are troublesome benign tumors of the larynx. According to their biological behavior, there are two types of laryngeal papillomas--the juvenile and adult types. Two samples of adult-type and five samples of juvenile-type laryngeal papilloma specimens were studied using the Southern blot technique with radioactively labeled human papillomavirus (HPV) 6b, 16, 18 deoxyribonucleic acid (DNA) as probes. We found that there was a linear form, an episomal form, and a concatemer or catenane of HPV DNA in the 5 samples of juvenile laryngeal papilloma and there was no evidence of HPV DNA integration. The HPV DNA in tumor cells is very closely associated with HPV 6b, but has no positive hybridization with HPV 16 and 18 DNA even in a low stringent condition. There was no positive hybridization found in the 2 samples of adult-type laryngeal papilloma with any of the three probes.

Cardiovascular effects of two disulfide analogues of sarafotoxin S6b

Sarafotoxin S6b (STX-b), a peptide toxin isolated from the venom of the Israeli burrowing asp, Atractaspis engaddensis, consists of 21 amino acid residues with four cysteines at positions 1,3,11 and 15. In the present study, we compared the cardiovascular effects of two synthetic STX-b analogues with different disulfide bridge locations, i.e. STX-b type A (1-15, 3-11) and STX-b type B (1-11, 3-15). At doses of 0.3-3 nmoles/kg (i.v.), type A produced a sustained pressor effect with transient increase in pulse pressure. However, at 5 nmoles/kg, it produced a transient increase followed by decrease in blood pressure, heart rate and respiratory rate within 30 sec and 12 out of 13 mice died within 10 min. Various kinds of ECG changes, suggestive of myocardial ischemia and hyperkalemia, were observed. Type A also caused a significant increase in the plasma levels of K+, lactate dehydrogenase, creatine phosphokinase, inorganic phosphate and glucose. By contrast, type B did not kill any mouse at doses up to 50 nmoles/kg. In the rat aorta, type A caused a potent vasoconstriction which was dependent on extracellular Ca2+ and was partially inhibited by verapamil and H-7, a protein kinase C inhibitor. In the rat Langendorff heart preparation, type A produced coronary vasospasm with potency about 100 times higher than that of type B. A similar potency ratio was observed for the positive inotropic effect in rat atria. These results indicate that the location of disulfide bridges in sarafotoxin S6b markedly influences the pharmacological potency and the natural sarafotoxin S6b should be type A with the disulfide bridge locations at positions 1-15 and 3-11.

Isolation and characterization of s-myc, a member of the rat myc gene family

A 9-kilobase-pair clone containing a myc-related gene that we have designated s-myc was isolated from a rat genomic library. The entire nucleotide sequence of the cloned DNA was determined, showing that the s-myc gene contains an open reading frame consisting of 1287 base pairs without introns. In vitro transcription-translation analysis of s-myc indicated that this gene produces a protein of approximately 50 kDa. The amino acid sequence predicted from the DNA sequence showed that the s-Myc protein is closely related to the murine N-Myc protein but lacks an acidic amino acid-rich sequence commonly present in the Myc-family proteins. Studies on transfection of s-myc into rat RT4-AC tumor cells revealed that the gene produces a polyadenylylated transcript of approximately 4.7 kilobases and that its high-level expression suppresses the tumor-igenicity of RT4-AC tumor cells in nude mice.

Developmental changes in the activities of phospholipase c, 3-kinase, and 5-phosphatase in rat brain

The specific activities of phospholipase C, 3-kinase, and 5-phosphatase were measured in brain homogenates from rats at different developmental stages. The activities of 3-kinase and 5-phosphatase increased by 14-fold and 2-fold, respectively, during development from fetus to adult, while PLC activity remained constant. These results suggest that the metabolism of inositol phosphates varies widely during development. In young brain stimulated by an agonist, it is predictable that Ins(1,4,5)P3 lasts longer and its average concentration is higher than in adult brain. The opposite is true for both the lifetime and concentration of Ins(1,3,4,5)P4. These developmental changes will invariably affect the property of Ca2+ oscillation and the effective time during which cells respond to the Ca2+-mobilizing agonists.

Intestinal absorption of zinc: sodium-metal-ligand interactions

The characteristics of zinc small intestinal absorption were investigated with the purpose of clarifying the role of sodium and the possible interaction among certain amino acids, oligopeptides, and zinc with electrolyte and water absorption. A perfusion procedure was used in anesthetized rats. Physiological concentrations of zinc with no ligands, or with twice the zinc levels of either Trp, His, Pro, or a protein hydrolysate (PrH) were pumped through jejunal or ileal segments. PrH was also used at a 10: 1 ratio to zinc. The osmotic solutes were either sodium chloride, glycerol, or NMG at isotonic concentrations. In the absence of LMW ligands, zinc transport appeared to occur only by diffusion, except in the ileum and in the presence of glycerol, where at low zinc concentrations a low affinity mediated transport component could be identified (Kt = 0.67 mM; Vmax = 1,160 pmole/min.cm. Glycerol generally elicited a greater overall zinc absorption rate as well as an enhanced net water uptake than when sodium chloride was the osmotic agent when either Trp, His, or Pro was present. The data indicate that sodium is not a requirement for zinc transport. In the presence of LMW ligands, which may also be from endogenous origin, bulk flow may be a major contributor of zinc translocation across the mammalian small intestinal mucosa.

Localized volume selection technique using an additional radial gradient coil

A volume selection technique for the localized NMR imaging using an additional radial gradient is proposed. This volume selection gradient is the fourth gradient in addition to the usual 3-dimensional imaging gradients, i.e., x-, y-, and z-directional gradients, and is of the radial form. The principle of the proposed method is the use of the radial gradient in conjunction with the selective RF pulse thereby selecting a small cylindrical volume which can be used for the 3-dimensional volume imaging with fewer encoding steps than those of the conventional full 3-dimensional volume imaging. The present technique combined with the fast steady state free precession gradient echo imaging sequence allows us to reduce the total scan time to several minutes for the 3-dimensional volume imaging with the spatial resolution of 1 x 1 x 1 mm or to spend the same scan time for the 3-dimensional imaging with improved spatial resolution. The basic principle of the radial gradient coil consisting of a main circular loop coil and an offset compensating Helmholtz coil is discussed and the construction details are presented. Some experimental results of the proposed volume selection imaging technique as well as computer simulation results are also given.

[A community-based study on risk factors of hypertension in Luh-Guu Township]

This is a community-based study on hypertension conducted in 1987 to assess the risk of demographic factors and life style of inhabitants aged over 30 in Luh-Guu Township. One-stage cluster sampling was applied. Through home visit interview, the height, weight, and blood pressure as well as demographic and life style data were taken, and 1171 (57.4%) valid data were completed. Hypertension was defined by American National Heart, Lung, Blood Institute as BP greater than = 140/90mmHg. The prevalence of hypertension was 29.2% (the prevalence was 13.4% if defined by the WHO criteria), and only 27.4% of those hypertensives were self-aware. Univariate analysis found that age, educational level, marital status, job condition, smoking habit, father's hypertension history, and usage of contraceptive were correlated with hypertension. With obesity index in addition to the above 6 factors, except contraceptive usage, as independent variables, the multiple logistic regression analysis showed that, only age and obesity index were significantly correlated with hypertension and the best model were fitted.

The incidence of congenital color deficiency among Koreans

It is important to investigate the incidence of congenital color deficiency and to determine the type and degree because the color deficiency can effect as a handicap to certain occupations. The incidence of congenital color deficiency is remarkably constant among Caucasians but other races show considerable variations. We investigated the incidence of congenital color deficiency among Koreans by the use of H-R-R pseudoisochromatic plates. The present study revealed that the incidence of congenital color deficiency among Koreans was 31.5% (5.90% in men, 0.44% in women).

Programmable quadratic associative memory using holographic lenslet arrays

Programmable higher-order optical interconnections between two-dimensional arrays of neurons are achieved by using holographic lenslet arrays and spatial light modulators. Basic experimental results for two-dimensional quadratic associative memory are reported to demonstrate its feasibility.

Dynamic viscous flow in distensible vessels of skeletal muscle microcirculation: application to pressure and flow transients

Blood flow in the microcirculation of the rat skeletal muscle during transient changes of arterial pressure is analyzed theoretically. Although flow in such small vessels is quasi-steady and has a very low Reynolds number, time-dependent nonuniform flows along the length of the blood vessels can be observed due to vessel distensibility. The governing equations for a single microvessel are derived using previously measured microvessel elasticity, and several solutions to different inflow and outflow pressures and flow conditions are investigated. The results indicate that when such distensible microvessels are subjected to a step increase of arterial pressure, the arterial flow shows a rapid overshoot followed by a progressive decay to steady-state. An arterial step flow induces a different response which takes the form of a monotonically increasing pressure. Pressure and flows are nonuniform along the vessel length during such transients. In-vitro whole organ pressure-flow data are presented in the dilated rat gracilis muscle which qualitatively agree with the theoretical predictions.

Studies of inositol phospholipid-specific phospholipase C

Inositol phospholipid-specific phospholipase C is the enzyme that generates phosphoinositide-derived messenger molecules. Mammalian cells contain at least five immunologically distinct phospholipase C enzymes that appear to be separate gene products. Complete amino acid sequences of four of these isozymes have been established. The overall sequence similarity is surprisingly low for enzymes catalyzing the same chemical reaction: three of them show limited amino acid sequence similarity to each other in two narrow regions, and the fourth enzyme is completely different. The diversity in primary structure together with different regional and cellular expression of the isozymes suggests that each isozyme has a defined function in processing the physiological response of different cell types to a variety of external stimuli and that each is regulated differently.

[Achalasia: report of two cases]

The first case, a two-month-old female infant, had frequent vomiting since 5 days of age. Dilated esophagus with narrowed distal end was noted on barium meal study. Panendoscopic examination revealed dilated esophagus and a pin-head sized, stenotic lumen at 15 cm from the incisor. Under the impression of esophageal stenosis, gastrostomy was performed for feeding. Esophagogram made at 6 months of age demonstrated good patency of the esophagus without stenosis and gastrostomy was subsequently closed at the age of 1 year. Unfortunately, swallowing disturbance had bothered her intermittently since. Barium esophagogram and panendoscopy made 8 years later again revealed distal esophageal obstruction with dilated proximal esophagus. The second case was a two and half year old boy who suffered from frequent regurgitation of undigested food for 6 months. Dilated esophagus with narrowing of the lower end of esophagus was noted on barium meal study. After admission, panendoscopic examination revealed the esophagus was very narrow at 25 cm from incisor and the proximal esophagus was dilated. The esophageal dilatation with mercury-weighted bougies was performed intermittently. At present he is doing well, and a barium meal study showed adequate esophageal emptying.

Fast SSFP gradient echo sequence for simultaneous acquisitions of FID and echo signals

Recently, the gradient echo imaging sequence in conjunction with small flip angle excitations and short repetition times has been widely used for fast NMR imaging. As the repetition time decreases to an extent comparable to the spin-spin relaxation time T2, the residual phase coherency of the transverse spin magnetization tends to form another nuclear signal which is heavily weighted by T2 and similar to a long TR/long TE spin-echo signal. This effect, although expected, has not been utilized in the conventional fast gradient echo imaging. When this residual phase coherency is utilized in conjunction with the fast SSFP (steady-state free precession) technique, both the FID and the echo signals can be obtained. In this paper, we have proposed a new technique by which simultaneous acquisitions of both the FID and the echo signals are possible. Experiments on this fast SSFP mode imaging have shown that the FID signal is T1-weighted while the echo signal is strongly T2-weighted. The flip angle optimal for maximizing signal and related contrast are also studied in conjunction with the proposed sequence and the experimental results are presented.

IgG2 subclass deficiency: IgG subclass assays and IgG2 concentrations among 8015 blood donors

Among the four IgG subclasses in humans, IgG2 is preferentially expressed in antibodies to carbohydrate antigens whereas IgG1 subclass is commonly associated with antibodies to protein antigens. Because of this association with carbohydrate antigens, values for IgG2 in serum are often used as an index of immunocompetence against carbohydrate antigens. To investigate the value of IgG2 measurements in a general population, we have developed a convenient IgG subclass assay, using monoclonal antibodies and particle concentration fluorescence immunoassay. Our assay is specific, precise, convenient, and accurate. When IgG2 concentrations were determined in the serum samples from 8015 adult blood donors, there were more individuals with low IgG2 concentrations than predicted by the log-normal distribution. The observed distribution suggested the presence of a subpopulation with low IgG2 concentration. Because apparently healthy individuals in a general population have low IgG2 concentrations, IgG2 measurements alone may have a limited clinical usefulness as an index of immune function against carbohydrate antigens.

IgG2 subclass deficiency: IgG subclass assays and IgG2 concentrations among 8015 blood donors

Among the four IgG subclasses in humans, IgG2 is preferentially expressed in antibodies to carbohydrate antigens whereas IgG1 subclass is commonly associated with antibodies to protein antigens. Because of this association with carbohydrate antigens, values for IgG2 in serum are often used as an index of immunocompetence against carbohydrate antigens. To investigate the value of IgG2 measurements in a general population, we have developed a convenient IgG subclass assay, using monoclonal antibodies and particle concentration fluorescence immunoassay. Our assay is specific, precise, convenient, and accurate. When IgG2 concentrations were determined in the serum samples from 8015 adult blood donors, there were more individuals with low IgG2 concentrations than predicted by the log-normal distribution. The observed distribution suggested the presence of a subpopulation with low IgG2 concentration. Because apparently healthy individuals in a general population have low IgG2 concentrations, IgG2 measurements alone may have a limited clinical usefulness as an index of immune function against carbohydrate antigens.

Optical short-pulse generation using diode lasers with negative optoelectronic feedback

A new method of optical short-pulse generation using stable diode lasers with negative optoelectronic feedback is proposed. Optical pulses with repetition rates of several gigahertz can be generated with a calculated pulse width of the order of a picosecond, and the required gain-bandwidth product of the feedback network is a few tens of gigahertz. This method does not require any external modulation signal, and it is not susceptible to critical optical alignment.

Optical implementation of the Hopfield model for two-dimensional associative memory

Optical implementation of Hopfield's neural network model [Proc. Natl. Acad. Sci. USA 79, 2554 (1982)] for two-dimensional associative memory is discussed. Two-state neuron elements are represented by a twisted nematic liquid-crystal optical switch array, and three-dimensional holographic interconnections are realized with these elements. Unipolar connections, created by adding a constant to bipolar interconnections and compensating them with an input-dependent thresholding operation, are realized. The 16- (4 x 4) neuron system model acts as a content-addressable associative memory with error-correction capability.

Modulation of cellular transglutaminase: protease-induced activation

Multiple molecular forms of transglutaminase are found in cells and each form is widely distributed. We find a 95 K dalton enzyme associated with membrane fractions. A 50 K dalton enzyme occurs primarily in epidermis and hair follicles. Cells after treatment with proteases show greater transglutaminase activity. The activated enzyme in rat chondrosarcoma cells is one of 95 K daltons, whereas mouse epidermal cells and rabbit endometrium cells after protease activation display enzymes of both 95 K daltons and 50 K daltons. The 95 K dalton enzyme, but not that of 80 K daltons, can be activated by proteases or sulfhydryl compounds after cell lysis. In cells that undergo terminal differentiation, e.g., reticulocytes, megakaryocytes, monocytes, chondrocytes, and epidermal cells, the forms of transglutaminase are modulated. Our findings suggest that these modulations in differentiating cells are the results of transglutaminase post-translational modifications that cause pronounced changes in catalytic activity.

Influence of pore and particle size on the frontal uptake of proteins. Implications for preparative anion-exchange chromatography

Several silica-based anion-exchange packings were synthesized with nominal pore sizes of 250, 500 and 1000 A in 10-, 20- and 50-micron particles. The static ("equilibrium") adsorption capacities for bovene serum albumin (mol. wt. 69,000), alpha-lactalbumin (17,500) and ferritin (440,000) were first measured using bulk material. The media were then packed into columns for frontal uptake experiments to measure adsorption from a flowing mobile phase. In general, frontal uptake was inversely related to both flow-rate and particle size. However, the magnitude of these relationships was strongly dependent on the pore to protein diameter ratio. More specifically, the uptake of bovine serum albumin was significantly more sensitive to linear velocity and particle size than alpha-lactalbumin. A mathematical model of the chromatographic process was used to calculate radial adsorption profiles across the chromatographic particle during frontal uptake. It was shown that restricted intraparticle diffusion due to insufficient pore size causes incomplete utilization of internal surface area. Under such conditions, protein is only bound within a finite shell on the outermost side of the particle; therefore, the effective loadability of the packing is greatly reduced. These data suggest that a pore size of at least 500 A will be required for the preparative chromatography of proteins with a molecular weight higher than ca. 100,000. This observation is especially evident when using particle sizes greater than 10 micron.

Efficient Tn10 transposition into a DNA insertion hot spot in vivo requires the 5-methyl groups of symmetrically disposed thymines within the hot-spot consensus sequence

Transposon Tn10 inserts preferentially at particular insertion "hot spots" that share a symmetrical 6-base-pair consensus sequence: 5' GCTNAGC 3'. The protein that recognizes this sequence is not known but is likely to be the Tn10-encoded transposase protein. We present evidence that the 5-methyl groups of the two thymines in this sequence are essential for efficient transposon insertion; in their absence the sequence is still recognized, but at lower efficiency. We have reached this conclusion by examination of a specific hot spot whose sequence is 5' GCCAGGC 3'. The innermost cytosines of this sequence happen to be substrates for methylation at their 5 positions by the bacterial dcm-encoded methylase. We find that Tn10 transposes into this site 15 times more frequently in a Dcm+ host than in a Dcm- host; in the Dcm- host, insertions still occur, but at a low frequency. Thus, at this site, the absence of pyrimidine 5-methyl groups at the third positions of the consensus sequence is sufficient to convert a strong insertion hot spot into a weaker but still recognizable hot spot. This observation supports the general proposition, suggested previously by comparisons among consensus sequences, that the presence or absence of these 5-methyl groups is one major feature that can make the difference between a strong and a weak Tn10 insertion hot spot.

Catalytic properties of inositol trisphosphate kinase: activation by Ca2+ and calmodulin

Inositol 1,4,5-trisphosphate (Ins-1,4,5-P3) is an important second-messenger molecule that mobilizes Ca2+ from intracellular stores in response to the occupancy of receptor by various Ca2+-mobilizing agonists. The fate of Ins-1,4,5-P3 is determined by two enzymes, a 3-kinase and a 5-phosphomonoesterase. The first enzyme converts Ins-1,4,5-P3 to Ins-1,3,4,5-P4, whereas the latter forms Ins-1,4-P2. Recent studies suggest that Ins-1,3,4,5-P4 might modulate the entry of Ca2+ from an extracellular source. In the current report, we describe the partial purification of the 3-kinase [approximately 400-fold purified, specific activity = 0.12 mumol/(min.mg)] from the cytosolic fraction of bovine brain and studies of its catalytic properties. We found that the 3-kinase activity is significantly activated by the Ca2+/calmodulin complex. Therefore, we propose that Ca2+ mobilized from endoplasmic reticulum by the action of Ins-1,4,5-P3 forms a complex with calmodulin, and that the Ca2+/calmodulin complex stimulates the conversion of Ins-1,4,5-P3, an intracellular Ca2+ mobilizer, to Ins-1,3,4,5-P4, an extracellular Ca2+ mobilizer. A rapid assay method for the 3-kinase was developed that is based on the separation of [3-32P]Ins-1,3,4,5-P4 and [gamma-32P]ATP by thin-layer chromatography. Using this new assay method, we evaluated kinetic parameters (Km for ATP = 40 microM, Km for Ins-1,4,5-P3 = 0.7 microM, Ki for ADP = 12 microM) and divalent cation specificity (Mg2+ much greater than Mn2+ greater than Ca2+) for the 3-kinase. Studies with various inositol polyphosphates indicate that the substrate-binding site is quite specific to Ins-1,4,5-P3. Nevertheless, Ins-2,4,5-P3 could be phosphorylated at a velocity approximately 1/20-1/30 that of Ins-1,4,5-P3.

Human T-cell leukemia virus type I infection in hemodialysis patients

Human T-cell leukemia virus Type I (HTLV-I) has been detected in a high proportion of individuals in Kumamoto prefecture (Kyushu) and Okinawa, where adult T-cell leukemia (ATL) is more likely to occur. The seroprevalence of antibody to HTLV-I was evaluated in hemodialysis patients and healthy individuals in the ATL endemic area. The prevalence of antibody to HTLV-I in 13,329 healthy controls was 3.6%, compared with 19.7% in 949 chronic hemodialysis patients. The prevalence of hemodialysis patients was significantly higher (P less than 0.01) than that in healthy individuals. Of 681 blood transfused patients who had undergone hemodialysis, 153 (22.5%) were seropositive, compared with 34 (12.7%) of the 268 who had not received the blood transfusion. The incidence was higher in dialysis patients who had been transfused than in those who had never received blood transfusions. Immune defects associated with uremia may have predisposed the patients to HTLV-I infection. Repeated antigenic stimulation from multiple infectious agents may have also played a role. The findings suggest an association between maintenance hemodialysis and HTLV-I infection, which can not be explained solely by blood or blood products.