Mortality and fertility: how large is the direct child replacement effect in China?

"The direct child replacement effect, that is the extent to which parents will have a child to replace one that died, was estime d by Olsen's method in China, using microdata from a sample survey of 4785 ever-married women in Hebei province taken in 1985. Olsen's method corrects for bias in the ordinary least squares estimate and uses mortality rates as an instrumental variable. Data for all age groups were pooled. Estimates of the direct replacement effect before and after correction for bias were 0.836 and 0.556, showing that over half of child deaths were replaced. The instrumental variable estimate produced a result of 0.614, similar to 0.613, computed by considering p1 to be random. A computation without instrumental variables yielded 0.774. The results showed that this method for calculating the direct replacement effect works well with these data because several of the alternative methods gave close estimates. There appears to be little family specific variation in child mortality rates, pointing out the effectiveness of Chinese primary health care. The direct replacement effect of about 0.6 is, however about 3 times that found by Olsen in Colombia and Malaysia, and close to the theoretical maximum. The reason for such a high value may be the small family size in China, where death of a child is more likely to provoke a response. Or it might suggest that severe government policy causes couples to attempt to have another child. Policy implications in this setting are that rather than make more contraceptives available, or improve infant survival, Chinese policymakers should make a small family size attractive, e.g., by improving education or pensions.

Socioeconomic determinants of fertility in China: a microeconometric analysis

"This paper reports the first set of estimates of the socioeconomic determinants of fertility in China using micro-data available from China's 1985 In-Depth Fertility Survey. Based on existing microeconomic theories of fertility, an econometric model was specified and estimated. The results indicate that even after age, marriage duration and child mortality are taken into account, education level of the woman, occupational status of the husband, the place of former and current residence, sex preference for boys, durable goods ownership, and family structure affect fertility."

Sodium and calcium currents in action potentials of rat somatotrophs: their possible functions in growth hormone secretion

We report that both Na+ and Ca2+ currents are involved in the action potentials and in the hormone release from rat somatotrophs in primary culture. Single somatotrophs were identified by reverse hemolytic plaque assay (RHPA) and transmembrane voltage and currents were recorded using the whole-cell mode of the patch-clamp technique. Somatotrophs displayed a mean resting potential of -80mV and an average input resistance of 5.7G omega. Most of the cells showed spontaneous or evoked action potentials. Single action potentials or the initial spike in a burst were characterized by their high amplitude and short duration. Tetrodotoxin (TTX, 1 microM) blocked single action potentials and the initial spikes in a burst, whereas action potentials of long duration and low amplitude persisted. Cobalt (2 mM) plus TTX (1 microM) blocked all the action potentials. Voltage-clamp experiments confirmed the presence of both a TTX-sensitive Na+ current and Co2(+)-sensitive Ca2+ currents. TTX or Na(+)-free medium slightly decreased the basal release of GH but did not markedly modify hGRF-stimulated GH release. However, Co2+ (2 mM), which partially decreased the basal release, totally blocked hGRF-stimulated release. We conclude that (1) Na+ currents which initiate rapid action potentials may participate in spontaneous GH release; (2) Ca2+ currents, which give rise to long duration action potentials and membrane voltage fluctuation, are probably involved in both basal and hGRF-stimulated GH releases.

The evolution of B-cell clones

This chapter identifies three forms of B-cell memory: (a) B blasts which characterize the established stage of the follicular response to TD antigens, (b) recirculating memory B cells, and (c) non-recirculating memory B cells of the marginal zones of the spleen and equivalent areas of other secondary lymphoid organs. The follicular B blasts show sustained proliferation driven by small amounts of antigen bound to FDCs. The probable relationships between these cells is summarized diagrammatically in Fig. 4. It is probable that follicular B blasts generate both the recirculating and marginal zone memory cells. The chapter by Gray and Leanderson in this volume cites data which indicate that the recirculating memory pool is not sustained for more than a few weeks in the absence of antigen. Data leading to the same conclusion for marginal zone memory B cells is set out in Sect. 5.1 of this chapter. Marginal zone memory B cells do not appear to move spontaneously to follicles for periodic renewal. They will only leave the marginal zone if a fresh supply of antigen reaches them in that site. Recirculating B cells are able to respond to antigen already held on FDCs. It is not known if they are able to displace B blasts of equivalent affinity for antigen which already occupy antigen-holding sites on FDCs. This could be a mechanism by which B blasts with high antigen affinity produced in one follicle could displace blasts of lower affinity in other follicles. Little is known of the factors which regulate the numbers of marginal zone and recirculating follicular memory B cells. In responses to hapten-protein conjugates, hapten-binding cells may approach 10% of marginal zone B cells but comprise well under 1% of recirculating follicular cells. The numbers of these memory cells do not increase if the recirculating pool of lymphocytes is depleted, indicating that the factors which regulate the number of memory B cells are independent of those which regulate the total size of the recirculating B-cell pool. A depleted peripheral B-cell pool can only be fully reconstituted by recruitment of newly produced virgin B cells. Data cited in Sect. 5.2 support the concept that this recruitment is at least partially independent of antigen-driven B-cell proliferation. Consequently, substantial proportions of the peripheral B-cell pools are likely to be either virgin cells or cells which have been recruited by antigen or anti-idiotype without entering cell cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Rapid cryopreservation of sheep embryos by direct transfer into liquid nitrogen vapour at -180 degrees C

The in vitro survival of control and rapidly cryopreserved sheep embryos was examined as a function of the duration of exposure to a vitrification medium (25% glycerol + 25% propylene glycol). Embryos in late morula to late blastocyst stages were permeated by a mixture of 10% glycerol + 20% propylene glycol for 10 min at 18-23 degrees C and then exposed to the vitrification medium for 0.5, 1, 2 or 4 min at 18-23 or 4-12 degrees C. The cryoprotectants were removed without cryopreservation (control embryos) or after rapid cryopreservation by direct transfer into liquid nitrogen vapour at -180 degrees C. The duration of exposure to the vitrification medium at 18-23 degrees C affected the in vitro survival rate of control embryos (P = 0.06) but had no effect on the survival of rapidly cryopreserved embryos. However, at 4-12 degrees C the duration of exposure affected the survival of cryopreserved embryos (0.5 min: 64%, 18/28; 1-4 min: 43%, 34/80; P = 0.074). Overall, the in vitro survival rate of control and cryopreserved embryos increased with advancing development from late morulae (36%) to late blastocysts (70%). The in vivo survival of embryos that had been exposed to the vitrification medium for 0.5 min at 4-12 degrees C and then vitrified was tested. The rate of development to term was 11% (4/35) for late morulae or early blastocysts and 32% (6/19; P greater than 0.1) for blastocysts to hatching blastocysts. These results showed that sheep embryos can be successfully cryopreserved by a simple, rapid procedure.

Molecular analysis of the isochromosome 12P in the Pallister-Killian syndrome. Construction of a mouse-human hybrid cell line containing an i(12p) as the sole human chromosome

An iso 12p chromosome from a patient with Pallister-Killian syndrome was successfully transferred into a mouse background by microcell-mediated chromosome transfer. The presence of the i(12p) chromosome was confirmed by karyotyping and by Southern blotting using five 12p and seven 12q probes. The isochromosome nature of the marker chromosome was confirmed by co-hydridization of a 12p probe with a 12q and an 8q probe. This cell line should be a valuable tool for physical mapping of 12p-derived DNA fragments; at the same time, it confirms the identity of the extra chromosome in the Pallister-Killian syndrome as i(12p).

Drug inhibitors of RNA polymerase II transcription

Transcription by RNA polymerase II occurs after formation of a transcription complex. This complex is assembled in stages by the interaction of transcription factors with the template and/or with each other. We report on the ability of six drugs to inhibit the assembly of the RNA polymerase II transcription complex. Assembly of the complex on the adenovirus major late promoter requires several transcription factors. The normal assembly process requires that the DNA first interact with TFIIA, then with TFIID, and finally with at least four additional transcription factors (one of which is RNA polymerase II). We observed that streptolydigin (10 micrograms/ml) inhibits association of ILA and IID, and at higher concentrations (100 micrograms/ml) inhibits that IIA/IID complex from binding to DNA. Streptovaricin (100 micrograms/ml) appears to inhibit the IIA/IID interaction with DNA and prevents reinitiation (at 500 micrograms/ml). Adriamycin (1 microgram/ml) inhibits the interaction of TFIID with the IIA/DNA complex and inhibits an additional event immediately prior to, or during, elongation. Daunorubicin may be an elongation inhibitor. Heparin at 10 micrograms/ml inhibits further assembly after the IIA/IID/DNA complex has formed, and at 100 micrograms/ml also inhibits a late event in the assembly process and blocks reinitiation. Rifamycin AF/013 (100 micrograms/ml) inhibits the early events necessary to form the IIA/IID/DNA complex and (at 10 micrograms/ml) an assembly event following formation of the IIA/IID/DNA complex. Therefore, these compounds should be useful as probes for further examination of the assembly process.

A cluster of alpha 2-macroglobulin-related genes (alpha 2 M) on human chromosome 12p: cloning of the pregnancy-zone protein gene and an alpha 2M pseudogene

The characterization of two alpha 2-macroglobulin (alpha 2M)-related genomic clones, isolated from two human genomic libraries by use of alpha 2M cDNA [Kan et al., Proc. Natl. Acad. Sci. USA 82 (1985) 2282-2286] as a probe, is reported. Sequence comparison of the clone EPZP6 with the human alpha 2M cDNA revealed the presence of five exons with the proper splice signals. Alignment of the corresponding amino acid (aa) sequence of these exons with the published partial pregnancy-zone protein (PZP) aa sequence (Sottrup-Jensen et al., Proc. Natl. Acad. Sci. USA 81 (1984) 7353-7357] showed a perfect match, thereby identifying EPZP6 as a PZP genomic clone. The clone MPAM16 showed a considerable degree of sequence conservation when compared to the human alpha 2M cDNA sequence, and several putative exons were identified. However, a frame-shift mutation leading to a premature stop codon was found in the coding sequence, classifying this gene as an alpha 2M pseudogene. Human alpha 2M, PZP and the related pseudogene were mapped to the human chromosome 12p12-13, with the help of gene-specific probes and in situ hybridization. This result was confirmed in Southern-blot experiments with DNA from a human-Ltk- mouse somatic-cell hybrid containing only a human isochromosome 12p in a mouse background.

Antisperm antibodies and sperm motility: a study using timed exposure photomicrography

This study examined the effect of antisperm antibodies on sperm motility. Antisperm antibodies present in seminal plasmas with different sperm agglutinating titres were transferred passively to normal donor sperm, and the effects on movement characteristics (velocity of forward progression, amplitude of lateral head displacement, percentage progressive motility and percentage non-progressive motility) were analysed using timed exposure photomicrography. There was no significant association between sperm movement characteristics and the presence of titre of antisperm antibodies in seminal plasma. Furthermore, no differences were detected between those samples that possessed sperm agglutinating versus sperm immobilizing activity. These findings do not support the common belief that antisperm antibodies are a cause of poor sperm motility in semen.

Scattering of incident KrF laser radiation resulting from the laser-induced breakdown of H(2)O droplets

The time history of elastically scattered incident radiation (ESIR) is presented for 60-microm-diameter water droplets irradiated by KrF (lambda = 248 nm) laser pulses with power densities in the range of 1-200 GW/cm(2). The ESIR shows a distinct two-peak structure that is dependent on the incident irradiance. The time delay between the arrival of the incident pulse and the first local minimum in the ESIR varied from 7 nsec at 200 GW/cm(2) to 21 nsec at 5 GW/cm(2). The time between incident pulse arrival and the first peak in the ESIR showed a similar irradiance dependence, with delays ranging from 4 to 12 nsec. Images of droplet breakup and the average velocities of ejected material are presented for times between 0 and 1000 nsec after the arrival of 3-GW/cm(2) laser pulses.

Glutamine auxotrophs of Bacillus subtilis that overproduce glutamine synthetase antigen have altered conserved amino acids in or near the active site

A number of mutations within the Bacillus subtilis glutamine synthetase (GS) gene result in altered catalytic properties and overproduction of the GS antigen. The restriction fragments containing mutations from three such mutants were sequenced, and they all had amino acid changes in conserved residues found either within or near sequences contributing to the active site of the Salmonella typhimurium GS.

The diagnostic significance of carbohydrate antigen CA 19-9 in serum and pancreatic juice in pancreatic carcinoma

CA 19-9 is a carbohydrate antigen isolated from human colon carcinoma cell line, and is reportedly a tumor marker for pancreatic carcinoma. In this study we determined serum CA 19-9 in 71 normal subjects, 103 patients with benign digestive diseases, 85 patients with periampullary cancers, and 160 patients with other digestive cancers. Serum CA 19-9 was elevated only in 2.3% of normals and benign digestive disease patients, whereas it was increased in 72.7%, 86.4%, and 89.5% of pancreatic, ampullary, and choledochal carcinoma patients, respectively. Of other digestive cancer patients, it was elevated in 23.8%. In addition, very high serum CA 19-9 (greater than 120 u/m) was more often observed in patients with pancreatic, ampullary, and biliary cancer patients than in GL cancer patients (54.1% vs 9.4%, p less than 0.001). In 18 normal subjects and 68 patients with benign and malignant diseases, it was found that CA 19-9 content in the pancreatic juice was significantly increased in pancreatic, ampullary, and choledochal cancer patients, whereas in chronic pancreatitis patients it was normal, indicating that it is a specific and valuable tumor marker in differential diagnosis of pancreatic cancer.

Partial primary structure of the 48- and 90-kilodalton core proteins of cell surface-associated heparan sulfate proteoglycans of lung fibroblasts. Prediction of an integral membrane domain and evidence for multiple distinct core proteins at the cell surface of human lung fibroblasts

Heparitinase treatment of cell surface-associated heparan sulfate proteoglycans (HSPG) of human lung fibroblasts reveals core proteins with apparent Mr values of 125,000, 90,000, 64,000, 48,000 and 35,000 (Lories, V., De Boeck, H., David, G., Cassiman, J.-J., and Van den Berghe, H. (1987) J. Biol. Chem. 262, 854-859). The 90- and 48-kDa core proteins share the epitope of the monoclonal antibody 6G12 which was used to screen a human lung fibroblast expression cDNA library. Rescreening of the libraries yielded clone 48K5 with an insert of 3439 base pairs. Polyclonal antibodies were raised in rabbits against a fragment of the protein encoded by the 48K5 cDNA different from the part carrying the 6G12 epitope. These antibodies specifically recognize the 90- and 48-kDa core proteins on Western blots of total cellular extracts of human lung fibroblast HSPG. The specific reactivity of the polyclonal antiserum confirms the identity of the 48K5 clone and further distinguishes the 48- and the 90-kDa core proteins, which do share the 6G12-defined epitope and at least one additional antigenic determinant with the 48K5 cDNA-encoded protein, from the 125-, 64-, and 35-kDa core proteins of cell surface HSPG of human lung fibroblasts which do not react with either antibody preparation. The protein encoded by the 48K5 clone contains a stop-transfer sequence indicative of an integral membrane protein and three potential glycosaminoglycan attachment sites. The 48K5 clone detects two major poly(A)+ RNA species in human lung fibroblasts presumably generated by the use of alternative polyadenylation signals. The 48K5 gene was mapped to chromosome 8q23 by in situ hybridization and hybridization to DNA of somatic cell hybrids.

[Effect of proglumide on choleresis in rats]

We are the first to report that proglumide (PGM) has a marked effect on promoting choleresis in rats. After iv infusion PGM 50, 100, 200, 400 mg/(kg.h), the bile quantities of 120-150 min were 0.4 +/- 0.14, 0.46 +/- 0.11, 0.75 +/- 0.25, 0.87 +/- 0.21 ml/30 min, respectively. They were significantly higher values than either basic bile flow (0.24 +/- 0.06 ml/30 min) or the solvent control of 5% NaHCO3 (0.22 +/- 0.13 ml/30 min, P less than 0.01) and obviously dose-dependent. After ig PGM 200 mg, bile flow observed at the peak of secretion between 60-90 min was 0.67 +/- 0.22 ml/30 min. Compared to that observed before PGM administration, the bile fluid collected was found to have increased 1.7-3.2 times, up to even 7 times. The choleretic effect continued 8-12 h after the infusion was terminated. The secretions of HCO3- and chlorides in the bile also increased during PGM infusion as compared with the control (P less than 0.05-0.01). On the contrary, the concentrations of cholic acids decreased remarkably (P less than 0.05-0.01). It is suggested that the mechanism of choleresis promoted by the infusion of PGM may be cholic acid-independent, but that it is related to the secretion of inorganic salts in cholangiole. Compared with three other choleretics commonly used clinically, phenylpropanol, dehydrocholic acid and sodium taurocholate, the effect of PGM is significantly superior (P less than 0.01).

Metabolism of n-VLDL and beta-VLDL in peritoneal macrophages from diabetic mice

Peritoneal macrophages were harvested from both healthy mice and mice with diabetes induced by intravenous injection of streptozotocin. After incubation with normal plasma very low density lipoprotein (n-VLDL) from swine for 24 h, the content of triglyceride (TG) in macrophages from diabetic mice was higher than that in the controls, and it was the same with the concentration of free fatty acid (FFA) in medium. The basic concentration of cholesterol ester (ChE) in macrophages from diabetic mice was also higher than that of the controls. After incubation with beta-VLDL from hypercholesterolemic rabbit for 48 h, no alteration in ChE content was found in the cells. On the contrary, the content of ChE in the cells from the controls was accumulated by saturating. The levels of FFA in the medium of the diabetic group were still higher than those of the controls. These results demonstrated that the metabolic function of peritoneal macrophages in diabetic mice was altered. The uptake and degradation of n-VLDL and the endogenous cholesterol synthesis were increased, but the uptake of beta-VLDL was lower. In this paper, the possible mechanism and the relationship between atherosclerosis and diabetes are discussed.

Amino acid sequence of a presynaptic neurotoxin, agkistrodotoxin, from the venom of Agkistrodon halys Pallas

The amino acid sequence of a presynaptic neurotoxin, agkistrodotoxin (ATX) isolated from the venom of Agkistrodon halys Pallas, was determined by automated Edman degradation and the carboxypeptidase digestion of the S-carboxymethylated ATX and by sequence analyses of peptides produced with cyanogen bromide cleavage and with trypsin or staphylococcal V8 protease digestion of the S-carboxymethylated ATX. ATX consists of 122 amino acid residues, including the histidine residue and 14 half-cystine residues. The amino acid sequence of ATX is very similar to those of toxic phospholipases and the phospholipase subunits of presynaptic neurotoxins from snake venoms. The residues responsible for the toxic activity of the presynaptic neurotoxins are discussed.

Inhibitory effects of atropine on growth hormone release in normal subjects and acromegaly

Growth hormone (GH) secretion is mediated by hypothalamic factors, mainly growth hormone releasing factor (GRF) and somatostatin (SS). The hypothalamic hormones, under direct neurotransmitter control, stimulate GH secretion through different central mechanisms. Atropine, an anticholinergic agent, can cross the blood-brain barrier and inhibit GH secretion stimulated by exercise and sleep in normal persons. In order to study the inhibiting effect of atropine on GH release and whether glucose can be replaced by atropine, normal persons and acromegaly patients were observed during exercise, after atropine, and 100 g glucose loading. The results confirmed that GH secretion increases after exercise and that this GH elevation can be inhibited by atropine in normal subjects. But in acromegaly patients high basal GH levels can not be inhibited by 100 g glucose loading or 0.6 mg atropine during the active phase of the disease. Blood sugar levels remained unchanged during the atropine test. It is suggested that the atropine test can be used as a GH inhibitory test in acromegaly patients with overt diabetes.

Localization of the PRR1 gene coding for rat prostatic proline-rich polypeptides to chromosome 10 by in situ hybridization

The gene coding for rat ventral prostatic proline-rich polypeptides (PRR1) was mapped to chromosome region 10q26----q31 by in situ hybridization. The high percentage (40%) of specific hybridization signal obtained is probably the result of the highly repetitive structure of the PRR1 gene.

Studies of beta-thalassemia mutations in families living in three provinces in southern China

beta-Thalassemia is a common disease in Southern China and 10 different mutations or frameshifts are responsible for most types of beta-thalassemia in this area. We studied 126 chromosomes of 80 beta-thalassemia patients from the Guangxi, Guangdong, and Sichuan Provinces using the polymerase chain reaction followed by dot-blot hybridization with specific oligonucleotide probes. The most common mutation in the three provinces is the frameshift at codons 41-42, followed by the A----T mutation at codon 17. The A----G mutation at nt -29 of the promoter is common in Sichuan but not in the other two provinces. Three mutations (T----C at nt -30; G----T at IVS-I-1, and G----C at IVS-I-5) were not observed. These data were used to initiate a prenatal diagnosis program using the same techniques for identification. Eleven fetuses at risk for beta-thalassemia have been diagnosed.

Dual-frequency phase conjugation wave generation with the high-order nonlinear effect by nondegenerate six-wave mixing in photorefractive Fe:LiNbO(3)

This paper demonstrates dual-frequency phase conjugation waves via the high-order nonlinear effect by nondegenerate six-wave mixing in iron-doped lithium niobate. In the experiment, two conjugation waves of different frequency are generated. Conjugation wave 1 is similar to nondegenerate four-wave mixing; conjugation wave 2 is completely different. The experiments measure the relationships between two conjugation wave intensities and parameters, respectively, and compare the differences of the two conjugation waves. To explain the experimental results, we assume that there is a fifth-order nonlinear interaction in crystal, and we believe the two conjugation waves are generated via different level nonlinear interactions. The theory agrees with the experimental results.

ATP secretion and extracellular protein phosphorylation by CNS neurons in primary culture

The significant role of secreted ATP in the regulation of neuronal function and the activity of ecto-protein kinases which utilize extracellular ATP to phosphorylate proteins localized at the cell surface have been previously studied in peripheral neurons and in cloned neural cell lines. In the present study we have utilized neostriatal neurons differentiated in primary culture to demonstrate vesicular secretion of ATP and phosphorylation of proteins by extracellular ATP in neurons derived from the central nervous system (CNS). Neostriatal neurons from embryonic mice were maintained in a chemically defined medium for 15-18 days. Functional differentiation was determined by measuring evoked GABA-release. ATP-secretion was measured by luciferin-luciferase assays, and protein phosphorylation by adding gamma-32P-ATP to the extracellular medium. Depolarization by 50 mM KCl induced a Ca++-dependent ATP release, and stimulation by 100 microM veratridine resulted in secretion of ATP that could be blocked by tetrodotoxin. Phosphorylation of specific protein components with apparent molecular mass of 110 Kd, 80 Kd, 55 Kd, 30 Kd and 20 Kd was detected in striatal neurons incubated for 15 min with gamma-32P-ATP added to the medium, but not by labeling intracellular ATP pools with equivalent amounts of radioactivity presented as inorganic 32Pi. These results open for investigation the role of extracellular protein phosphorylation systems in processes underlying the responsiveness of CNS neurons to secreted ATP.

B cell memory to thymus-independent antigens type 1 and type 2: the role of lipopolysaccharide in B memory induction

Several studies have indicated that thymus-independent (TI) antigens, unlike their thymus-dependent (TD) counterparts, are poor at generating memory antibody responses (Immunol. Today 1981. 3:217). In contrast to this view, the present report shows that the TI type 1 (TI-1) antigen, 2,4,6-trinitrophenyl-lipopolysaccharide (TNP-LPS), elicits good secondary responses in rats. These secondary antibody responses are not only greater in magnitude than the primary responses, but display a different pattern of Ig classes with more IgG and IgA antibodies produced. In transfer experiments between congenic strains of rats which differ in their kappa light chain Ig allotype, it is shown that this memory is attributable to persistent B cell clones. The TI-2 antigen, 2,4-dinitrophenyl-hydroxyethyl starch (DNP-HES), given alone did not elicit B cell memory. However, when DNP-HES is presented to the immune system in association with LPS, the pattern of the anti-DNP response is similar to that elicited by TNP-LPS. The capacity to generate TI memory is associated with the appearance of hapten-specific B cells in the marginal zones of the spleen. Hapten-binding cells were induced in the marginal zones following immunization with TNP-LPS, but not by DNP-HES. However, concurrent immunization with DNP-HES and LPS which were not covalently linked was found to induce DNP-binding cells in the marginal zone. There is complete correlation between the appearance of hapten-binding memory B cells in the marginal zone and the capacity of these antigens to induce secondary responses.

Is rapid proliferation in B centroblasts linked to somatic mutation in memory B cell clones?

Antigen-reactive B cells accumulate mutations in the variable (v) regions of their immunoglobulin genes during certain phases of T cell-dependent (TD) antibody responses. This is associated with a rise in the affinity of specific antibody. The time when somatic mutations are accumulating seems to coincide with the presence of germinal centres. This has led to the suggestion that a mechanism leading to a high rate of base pair substitution in immunoglobulin v region genes might operate in centroblasts in germinal centres. The rate of accumulation of mutations in v region genes is likely to relate to the number of specific B cells in cycle and their rate of cell division. The present report provides evidence pointing to centroblasts having a remarkably short cell cycle time of some 6 to 7 hours. This rapid rate of proliferation may explain the clonal expansion which occurs in the early phase of TD antibody responses and the efficiency with which high affinity mutants are subsequently selected.

Alterations in lipid composition and fluidity of liver plasma membranes in copper-deficient rats

In view of the importance of membrane fluidity on cell functions, the influence of phospholipid acyl groups on membrane fluidity, and the changes in lipid metabolism induced by copper (Cu) deficiency, this study was designed to examine the influence of dietary Cu on the lipid composition and fluidity of liver plasma membranes. Male Sprague-Dawley rats were divided into two dietary treatments, namely Cu deficient and Cu adequate. After 8 weeks of treatment, liver plasma membranes were isolated by sucrose density gradient centrifugation. The lipid fluidity of plasma membranes, as assessed by the intramolecular eximer fluorescence of 1,3-di(1-pyrenyl) propane, was significantly depressed by Cu deficiency. In addition, Cu deficiency significantly reduced the content of arachidonic and palmitoleic acids but increased the docosatetraenoic and docosahexaenoic acids of membrane phospholipids. This alteration in unsaturated phospholipid fatty acid composition, especially the large reduction in arachidonic acid, may have contributed to the depressed membrane fluidity. Furthermore, Cu deficiency also markedly altered the fatty acid composition of the triacylglycerols associated with the plasma membranes. Thus, the lipid composition and fluidity of liver plasma membranes are responsive to the animal's Cu status.

Frequency-varied conjugation wave generation via nondegenerate four-wave mixing in Fe:LiNbO(3) crystal

This paper demonstrates the frequency-varied conjugation wave generation via nondegenerate four-wave mixing in photorefractive iron-doped lithium niobate crystal. The experiment uses 4880- and 6328-A laser beams as mixing waves. The results are different from nearly degenerate four-wave mixing. The conjugation wave intensity depends on many parameters.

Orally administered kappa as well as mu opiate agonists delay gastrointestinal transit time in the guinea pig

When an orally administered opiate agonist is systemically bioavailable, the relative activity of that opioid in delaying gastrointestinal transit (GIT) depends on its relative action at central and peripheral sites. This in turn depends on the density of opioid receptor specific subtypes at those sites of action in the species under study. In rats the kappa selective agonist U-50,488H has no effect on GIT. We have found that this same agonist is equipotent to mu agonists morphine and 1-methadone in delaying the orocecal transit of a charcoal meal when administered orally to guinea pigs. Thus, both kappa as well as mu receptor subtypes are involved in the mechanisms of opiate induced slowing of GIT in the guinea pig in contrast to the rat. Interspecies differences must be considered when determining the contribution of opiate receptor subtypes to the mechanisms of opiate-induced constipation.

The relationship between Hb Bart's levels in cord blood and the deletions of alpha-globin genes

A relationship between Hb Bart's levels in cord blood and the number of alpha-globin genes has been established by screening cord blood samples from 1,075 newborn babies. Diagnosis was made by gene mapping of DNA samples with restriction endonuclease digestion. The presence of Hb Bart's was determined with a discontinuous microelectrophoresis on cellulose acetate at pH 8.34. The establishment of this relationship allows an early diagnosis of alpha-thalassemia by this simple microelectrophoretic procedure.

Mapping of rat prostatic binding protein genes C1, C2, and C3 to rat chromosome 5 by in situ hybridization

Rat prostatic binding protein genes C1, C2, and C3 were mapped on rat chromosome 5 by in situ hybridization on rat peripheral blood chromosome preparations using three different cDNA probes. Of the grains detected, 15.9%, 25.2%, and 19.6%, respectively, mapped to chromosome 5. For each probe, the label was predominantly located on 5q31, but for C2 and C3 an additional site on 5q21 was found. The results suggest that three genes coding for the different polypeptide chains of rat prostatic binding protein map to the same chromosome and presumably to the same chromosome band.

Optical sine transformation

The phase mask distribution of optical sine transformation (OST) has been calculated according to the optical general transformation theory. To avoid the diffraction loss of the phase mask, the optical waveguide method is used. Computation shows that the optical sine transformation is possible with only one phase mask, i.e., one-half of a cylindrical lens in the 1-D case and one-quarter of a spherical lens in the 2-D case. Experimental results agree with the theoretical prediction. Image compression by OST is also given.

The transforming protein of avian reticuloendotheliosis virus is a soluble cytoplasmic protein which is associated with a protein kinase activity

We have identified the product (p57v-rel) of the transforming gene, v-rel, of avian reticuloendotheliosis virus (REV-T) using antisera generated against nonoverlapping sequences representing the middle and carboxy-terminal regions of the v-rel protein expressed in Escherichia coli (N.K. Herzog and H.R. Bose, Jr., 1986, Proc. Natl. Acad. Sci. USA 83, 812-816). The amino-terminal region of the v-rel protein was also expressed in E. coli and used to generate antisera. The immunoglobulin-enriched fractions of these antisera were used to determine the subcellular location of p57v-rel in REV-T transformed lymphoid cells. Cells were fractionated into nuclear, mitochondrial, microsomal, and cytoplasmic fractions. The majority of p57v-rel was found in the cytoplasm. Examination of REV-T transformed lymphoid cells labeled with 32Pi revealed that the majority of the phosphorylated form of the v-rel protein was also found in the cytoplasm. Indirect immunofluorescence of REV-T transformed cells gave a diffuse cytoplasmic pattern indicating that p57v-rel was not associated with any discrete cellular organelle. The distribution of p57v-rel was similar in REV-T transformed lymphoid cells labeled with [35S]methionine for short and long periods of time, suggesting that p57v-rel is a soluble cytoplasmic protein throughout its lifetime. The v-rel protein was phosphorylated when immune complexes precipitated from transformed cells with the immunoglobulin fractions obtained from antisera against the amino-terminal, middle, and carboxy-terminal regions of v-rel were incubated with [gamma-32P]ATP and Mn2+. The phosphorylation of p57v-rel in the in vitro immune complex kinase assay was inhibited when the immunoglobulin-enriched fraction of these antisera was preincubated with the homologous v-rel fusion proteins. Preincubation with heterologous proteins did not block the phosphorylation of p57v-rel. These observations suggest that p57v-rel is associated with a protein kinase activity. Most of the kinase activity was found in the soluble cytoplasmic fraction of transformed cells. The transforming protein encoded by v-rel is a relatively stable protein with a half-life of approximately 7 to 8 hr in transformed lymphoid cells.