UV photoelectron spectroscopy and ab initio characterization of valence orbital structures and conformations of neutral phosphate esters

The HeI UV photoelectron spectrum of trimethyl phosphate (TMP) has been measured and interpreted with the aid of SCF molecular orbital calculations carried out with STO-3G, STO-3G* and 4-31G basis functions. The photoelectron spectrum of TMP is more accurately reproduced by results from 4-31G calculations than by results from STO-3G or STO-3G* calculations. However, all three basis sets yield results which predict the same assignment of the photoelectron spectrum. Results at the 4-31G level indicate that whether calculations are based on crystallographic bond angles and bond lengths or on STO-3G optimized geometries has little effect on the energetic ordering of the upper occupied orbitals. The energetic ordering of orbitals is also found to be only weakly dependent upon the torsional angle phi, describing rotation of ester groups about P-O bonds and upon the torsional angle psi, describing rotation of methyl groups about C-O bonds. For trimethyl phosphate, with C3 symmetry, the vertical ionization potentials of the upper occupied orbitals are 10.81 eV (8e), 11.4 eV (9a), 11.93 eV (7e), 12.6-12.9 eV (8a and 6e), 14.4 eV (7a) and 15.0-16.0 eV (5e and 6a). Calculations at the 4-31G level indicate that many of the highest occupied orbitals in neutral dimethyl phosphate and methyl phosphate have energies and electron distributions similar to orbitals in TMP. For TMP, a search for optimized values of phi and psi has been carried out at the STO-3G*level. In agreement with previous NMR studies and with classical potential calculations, the STO-3G* results indicate that both the gauche (phi = 53.1 degrees) and anticlinal (phi = 141.9 degrees) conformations are thermally accessible. Also in agreement with the classical potential calculations, the STO-3G* results predict that in the all gauche conformation energy is minimized when the methyl groups assume a staggered geometry (psi = 60 degrees to 80 degrees) and that an energy maximum occurs for an eclipsed geometry (phi = 0 degrees to 20 degrees). A study of the dependence of optimized values of O-P-O ester bond angles on the torsional angles, phi, was carried out at the STO-3G, STO-3G* and 4-31G levels. The results demonstrate that for C3 symmetry, the coupling of O-P-O angles to phi is influence by repulsive steric interactions.

High-affinity binding of [3H]estradiol-17 beta by an estrogen receptor in the liver of the turtle

Specific [3H]estradiol-17 beta ([3H]E2) binding activity (EBA) with characteristics of an estrogen receptor (ER) was demonstrated in cytosols and nuclear extracts of the female turtle, Chrysemys picta. Three different receptor assays (dextran-coated charcoal assay, hydroxylapatite batch procedure, and DNA-cellulose chromatography) were evaluated in terms of their applicability in analyzing large numbers of samples. For the measurement of cytosolic EBA, the hydroxylapatite batch procedure was found to be the most reliable assay. On the other hand, the dextran-coated charcoal assay was found to be the most appropriate method for the measurement of nuclear EBA. Turtle hepatic EBA binds [3H]E2 with high affinity (cytosolic, 17.4 +/- 2.8 X 10(9) M-1; nuclear, 17.7 +/- 1.9 X 10(9) M-1), limited capacity (cytosolic, 133.7 +/- 4.6 fmol/g tissue; nuclear, 81.1 +/- 9.0 fmol/g tissue), and strict steroid specificity. The EBA bound natural estrogens (E2, estrone, estriol) as well as the nonsteroidal estrogen, diethylstilbestrol, but exhibited little affinity for androgens, progesterone, or corticosterone. The turtle hepatic EBA resembled mammalian and avian ERs in terms of binding characteristics; however, unlike mammalian and avian ERs it was shown to be heat-labile. Incubation at 30 degrees caused rapid loss of [3H]E2 binding activity in both cytosolic and nuclear fractions. The exchange between [3H]E2 and the endogenously bound estrogen was slow at 4 and 15 degrees, but the exchange process was facilitated in the presence of the chaotropic salt, NaSCN. Establishment of quantitation methods for both cytosolic and nuclear forms of EBA will enable future investigation of the mechanism and regulation of estrogen action in the liver of this turtle species.

Calcium entry into the inositol 1,4,5-trisphosphate-releasable calcium pool is mediated by a GTP-regulatory mechanism

Intracellular Ca2+ release activated by inositol 1,4,5-trisphosphate (InsP3) plays a pivotal role in Ca2+ signaling in cells. A controlling mechanism for InsP3-induced Ca2+ movements is suggested by results showing that the InsP3-releasable Ca2+ pool is directly modified by a specific and sensitive GTP-regulated Ca2+-translocating process. By using saponin-permeabilized N1E-115 neuroblastoma cells or DDT1MF-2 smooth muscle-derived cells, InsP3 releases 30-50% of Ca2+ accumulated through intracellular high-affinity ATP-dependent Ca2+-pumping activity. Oxalate-promoted Ca2+ uptake is reversed by InsP3, indicating oxalate permeability of the InsP3-releasable pool, which is consistent with this compartment being the endoplasmic reticulum. GTP (10 microM) activates release of 50-70% of accumulated Ca2+ from cells. In the presence of 5-10 mM oxalate, GTP induces a biphasic Ca2+ flux response; initially (1-2 min) GTP induces rapid Ca2+ release followed thereafter by a profound increase in Ca2+ uptake. Thus, GTP-activated Ca2+ influx and efflux compete for Ca2+ access to the oxalate-permeable Ca2+ pool. The nonadditive effects of InsP3 and GTP suggest that InsP3 releases Ca2+ from a subcompartment of the GTP-releasable pool. Most significantly, InsP3 is observed to block the GTP-activated uptake phase in the presence of oxalate, indicating that GTP induces Ca2+ entry into the pool from which InsP3 activates release. Hence, the results provide direct evidence that loading of Ca2+ into the InsP3-sensitive Ca2+ pool is controlled by a GTP-regulated Ca2+-translocating mechanism. Such a process could be significant in regulating the extent and duration of the InsP3-induced Ca2+ signal, a crucial step in the inositol phospholipid signaling pathway.

[Two cases of adrenal myelolipoma]

Myelolipoma of the adrenal gland is a benign oligosymptomatic tumor composed of various proportions of fat and bone marrow elements. We report two operated cases found incidentally in a 76-year-old man and 49-year-old man.

Influenza surveillance in Singapore: 1972-86

Prospective laboratory surveillance of influenza viruses has been carried out since 1973 in Singapore. The results indicate that antigenic shift variants caused epidemics at various times of the year over this period, whereas drift variants were associated with a regular increase in incidence during the second and fourth calendar quarters. Outbreaks due to influenza A virus occurred every year and to influenza B virus at intervals of 16-24 months. Between outbreaks, viruses belonging to either of the two types could be detected during most months, and certain variants appeared several months before the outbreaks they subsequently caused. The factors that contribute to the seasonal pattern are at present unknown.

Effect of morpholinyladriamycin analogs and adriamycin on the activities of DNA polymerase alpha and RNA polymerase II of chicken leukemia cells

The new adriamycin (ADR) derivatives, 3'-deamino-3'-(4"-morpholinyl)adriamycin (MRA) and 3'-deamino-3'-(3"-cyano-4"-morpholinyl)-adriamycin (MRA-CN), were studied, in comparison with ADR, for their inhibitory effects on DNA and RNA syntheses in vitro using isolated DNA and RNA polymerases from both Escherichia coli and chicken (myeloblastosis) leukemia cells. Under standard assay conditions, MRA and ADR demonstrated a similar inhibitory effect on the enzymes, whereas MRA-CN showed a slightly greater inhibitory activity than ADR or MRA at low drug concentrations, but with the inhibitory effect plateauing when drug concentration reached 10 microM. Both the A and B forms of the MRA-CN diastereoisomers were effective as inhibitors. Kinetic studies of the inhibition showed that unlike ADR, MRA-CN inhibition of DNA or RNA synthesis could not be reversed by increasing DNA-template concentration in the reaction mixture. Whereas ADR or MRA relaxed completely 1 microgram of pBR322 supercoiled DNA at a drug concentration of 15 microM, MRA-CN, at 60 microM, produced a mixture of intermediate relaxation forms of the DNA. A complete relaxation was achieved at 300 microM MRA-CN. Both DNA relaxation and fluorescence spectroscopic studies indicated that DNA-drug interactions occurred in the following order: ADR (or MRA) greater than MRA-CN greater than N-trifluoroacetyl-ADR-14-O-hemiadipate (a DNA-nonbinding anthracycline).

Site and stage specific action of endogenous nuclease and micrococcal nuclease on histone genes of sea urchin embryos

The early histone genes of sea urchin embryos are expressed exclusively during cleavage stages of embryogenesis. The chromatin containing these genes was examined by nuclease sensitivity. An endogenous nuclease active during cleavage, produces 1300-bp segments containing early histone genes. The cutting sites have been mapped; there are very sensitive sites close to the cap site for H1, H2A, H2B, and H4. Chromatin obtained from embryos of later stages, when the genes are not expressed, do not display this pattern of nuclease sensitivity. Micrococcal nuclease produces nucleosomes that contain histone genes when used with nuclei from later stages, but not with nuclei from cleavage stages.

Hypoxic and nycthemeral responses by the adrenal cortex of partially hepatectomized rats

Adrenocortical nycthemeral (day-night alteration) and hypoxic stress responses of rats were evaluated 48 h following 70% hepatectomy. Morning plasma and adrenal corticosterone concentrations of hepatectomized (H) rats at 0800 hours were significantly higher than those of sham (S) operated animals. Although both groups showed significant nocturnal elevations in these parameters at 2000 hours, the nocturnal rises in plasma corticosterone levels were 75% and 223% in H and S rats, respectively, yet the absolute steroid levels did not differ between the groups. The hypothalamic-pituitary-adrenocortical (HPA) response of H animals to hypoxia was assessed by measuring plasma corticosterone levels at various times before, during and after exposure to 10% O2 at ground level. Curvilinear analysis of the plasma steroid levels revealed a significantly slower corticosterone rise during the hypoxic phase in H than S animals, as well as a much slower return to baseline levels after the hypoxic stimulus was terminated. The latter indicates a decreased hepatic capacity to inactivate steroids in H animals, while the sluggish activation of the HPA system by hypoxia may be due to altered neuroendocrine control resulting from prior exposure of feedback sites to elevated basal plasma corticosterone levels.

Activation of nonspecific killer cells by interleukin 2-containing supernatants

In the absence of specific antigen stimulation, nonspecific killer cells were induced by culturing C57BL/6 lymph node or spleen cells with interleukin 2-containing supernatants. These supernatants were obtained from stimulation of either rat spleen cells with concanavalin A or a variant of the T cell lymphoma, EL4 (H-2b) with phorbol myristic acetate. The ability of the EL4 supernatant to induce nonspecific killer cells was abrogated by absorption with an interleukin 2-dependent T cell line or by concanavalin A-stimulated spleen cell blasts, but not by lipopolysaccharide-stimulated spleen cell blasts or by a non-interleukin 2-producing EL4 line. Partially purified interleukin 2 from EL4 supernatants could also support nonspecific killer cell induction. The induction of cytolytic cells by interleukin 2 is sensitive to gamma-irradiation and has a D omicron of 120 rad. The nonspecific killer cells induced are likely cytotoxic T lymphocytes; the majority of the precursor and effector cells bear the Thy-1 alloantigen marker. These nonspecific killer cells killed a broad spectrum of target cells, including concanavalin A- and lipopolysaccharide-induced splenic blasts of syngeneic or allogeneic mice, a syngeneic tumor, and a cloned allogeneic cytotoxic T cell line. The frequency of precursors for nonspecific killer cells in C57BL/6 lymph node and spleen cells are 1/7000 and 1/12,000, respectively. Clonal analyses revealed that these nonspecific killers exhibit heterogeneity with respect to their target cell specificities. The induction of nonspecific killers by interleukin 2-containing supernatants is partially dependent on nylon wool-adherent cells; in antigen-stimulated cultures the most specific killer cells were obtained from cultures in which nylon wool-nonadherent lymph node responder cells were stimulated with nylon wool-nonadherent allogeneic splenic stimulator cells that were treated with anti-Thy-1 antibody and complement. The relevance of these findings with respect to the frequencies and fine specificities of cytotoxic T lymphocytes generated in interleukin 2-supplemented cultures is discussed.

Activation of nonspecific killer cells by interleukin 2-containing supernatants

In the absence of specific antigen stimulation, nonspecific killer cells were induced by culturing C57BL/6 lymph node or spleen cells with interleukin 2-containing supernatants. These supernatants were obtained from stimulation of either rat spleen cells with concanavalin A or a variant of the T cell lymphoma, EL4 (H-2b) with phorbol myristic acetate. The ability of the EL4 supernatant to induce nonspecific killer cells was abrogated by absorption with an interleukin 2-dependent T cell line or by concanavalin A-stimulated spleen cell blasts, but not by lipopolysaccharide-stimulated spleen cell blasts or by a non-interleukin 2-producing EL4 line. Partially purified interleukin 2 from EL4 supernatants could also support nonspecific killer cell induction. The induction of cytolytic cells by interleukin 2 is sensitive to gamma-irradiation and has a D omicron of 120 rad. The nonspecific killer cells induced are likely cytotoxic T lymphocytes; the majority of the precursor and effector cells bear the Thy-1 alloantigen marker. These nonspecific killer cells killed a broad spectrum of target cells, including concanavalin A- and lipopolysaccharide-induced splenic blasts of syngeneic or allogeneic mice, a syngeneic tumor, and a cloned allogeneic cytotoxic T cell line. The frequency of precursors for nonspecific killer cells in C57BL/6 lymph node and spleen cells are 1/7000 and 1/12,000, respectively. Clonal analyses revealed that these nonspecific killers exhibit heterogeneity with respect to their target cell specificities. The induction of nonspecific killers by interleukin 2-containing supernatants is partially dependent on nylon wool-adherent cells; in antigen-stimulated cultures the most specific killer cells were obtained from cultures in which nylon wool-nonadherent lymph node responder cells were stimulated with nylon wool-nonadherent allogeneic splenic stimulator cells that were treated with anti-Thy-1 antibody and complement. The relevance of these findings with respect to the frequencies and fine specificities of cytotoxic T lymphocytes generated in interleukin 2-supplemented cultures is discussed.

Adoptive transfer of delayed wattle reactivity in chickens with a dialyzable leukocyte extract containing transfer factor

Delayed wattle reactions (DWR) to tuberculin, diphtheria toxoid (DT), and keyhole limpet hemocyanin (KLH) were transferred to chickens with dialyzable leukocyte extracts (DLE) prepared from splenic leukocytes of chickens sensitized and reactive by DWR to the tuberculin, DT, or KLH. A DLE prepared from chickens unsensitized and unreactive to tuberculin by DWR failed to transfer DWR to tuberculin in recipients. Only chickens injected with DLE from tuberculin sensitized and reactive chickens exhibited significant (P less than .01) DWR to tuberculin. Chickens that received DLE prepared from DT sensitized and reactive chickens exhibited significant (P less than .01) DWR to DT but not to KLH. Further, DWR to both DT and KLH was transferred with DLE prepared from chickens sensitized to both antigens. Adoptive transfer of DWR to KLH in comparison to DT was more successful. Finally, the serial transfer of DWR to KLH (P less than .05) but not to DT (P greater than .05) was accomplished using DLE prepared from chickens that previously were recipients of DLE prepared from chickens sensitized to KLH and DT. Results indicate that DLE prepared from chickens contain transfer factor (TF) responsible for adoptive transfer of DWR to tuberculin, DT, and KLH.

Field trials with an oil emulsion infectious bursal disease vaccine in broiler breeder pullets

Two independent field trials were undertaken with commercial broiler companies in separate sections of Alabama in order to test the efficacy of an experimental commercially prepared oil emulsion infectious bursal disease (IBD) vaccine in broiler breeder pullets. The IBD vaccine was tested both for safety and the production of neutralizing antibodies in pullets and their progeny as well as its ability to prevent early field exposure to virulent IBD virus (IBDV) in broiler progeny that may lead to immunosuppression resulting in poor performance. The following was demonstrated in both trials: 1) the IBD vaccine had no adverse effect on breeder performance, 2) the IBD antibody titers in breeders peaked at 10 weeks postvaccination (PV) and remained about 1.5 to 4 times higher than nonvaccinated breeders through 25 weeks (PV), 3) 1-day IBDV maternal titers in broilers were related to the parental titers, 4) the IBD vaccination in pullets prevented early infection to field IBDV in progeny as determined by antibody titers and various performance parameters.

Pathology services in Singapore

The provision of an adequate Pathology Service is essential for the rational diagnosis, management and control of diseases. In Singapore such a need has long been recognised, and the service has made substantial progress since it started.

Immune selection of tumor cell variants in chickens bearing tumors induced by avian sarcoma virus

We have compared avian sarcoma cells, cultured from tumors at various stages of growth, in terms of their ability to synthesize infectious progeny virus and to express antigens that are reactive with the sensitized lymphocytes of tumor-bearing hosts. Cell-mediated immunity in chickens bearing tumors induced by avian sarcoma viruses was monitored by each of a target cell cytotoxicity test and an antigen-driven lymphocyte stimulation assay. Our results show that it is only those tumor cells which have been derived from progressively growing neoplasms that are able to synthesize infectious progeny virus and to specifically interact with the sensitized lymphocytes of tumor-bearing hosts. In contrast, cells from regressing tumors do not express relevant antigens to the same extent as do progressors, and they synthesize noninfectious particles only. Experiments on cellular outgrowths, derived from the plating at limited dilution of progressively growing tumor cells, revealed that such producers of defective virus are present at the earliest stages of tumor growth. Both these cells and regressing tumor cells are poorly stained (about 10%) in indirect immunofluorescence tests by antiserum against viral envelope glycoprotein, whereas tumor cells from progressing neoplasms react well (about 60 to 85%). These results suggest that tumor cells which are found in regressing neoplasms are selected out by a functional immune response directed against cells which are efficient producers of progeny virus.

Non-specific effects of avian retrovirus co-incubation on lymphocyte function: abrogation of antigen- and mitogen-induced proliferative responsiveness

Peripheral blood lymphocytes from chickens bearing tumours induced by avian retroviruses can be stimulated to divide by group-specific antigens present in supernatant fluids of avian retrovirus-infected but not normal chicken embryo fibroblast (CEF) cells. Centrifugation studies revealed that the relevant antigenic activity is non-virion in nature. Indeed, the presence of avian retrovirus particles was found to be inhibitory to the capacity of sensitized lymphocytes to be stimulated in this antigen-driven blastogenesis assay. Similar results were obtained in lymphocyte mitogenesis experiments in which any of peripheral chicken lymphocytes or mouse splenic, lymph node or thymic lymphocytes were co-incubated with either concanavalin A or phytohaemagglutinin in the presence of numerous types of virus particles. This inhibitory effect was not due to infection of lymphocytes by the viruses tested, and was obtained in the case of lymphocyte-virus combinations for which the cells lacked the surface receptors required for viral entry. Virus could be added to lymphocyte cultures as late as 26 h after co-incubation with mitogen, and still inhibit the usual mitogenic response. In addition, co-addition of virus to lymphocytes in the presence of concanavalin A was found to block the capping of ligand-bound receptors which normally ensues. Pre-added virus did not, however, affect the ability of lectins to bind to cells.

Decreased production of transforming virus and altered antigenic behaviour in cultured avian sarcoma cells

Tumours induced in chickens by inoculation of avian sarcoma viruses are frequently capable of undergoing spontaneous regression. It is only those tumour cells which have been derived from progressively growing neoplasms that are able to produce transforming progeny virus in vitro and to shed into the culture medium antigens which are specifically reactive with the peripheral lymphocytes of sarcoma-bearing hosts. Following multiple passages and extended growth in culture, however, the ability of these tumour cell fluids to stimulate the lymphocytes of sensitized hosts diminishes in concert with the declining capacity of these cells to continue to synthesize fully transforming progeny virus. In certain instances, however, aged tumour cells are able to synthesize particles which contain the enzyme RNA-dependent DNA polymerase yet lack detectable envelope glycoprotein.

Adrenal and plasma corticosterone of hepatectomized rats: responses during hepatic restoration

Adrenal and plasma corticosterone concentrations of partially (70%) hepatectomized male rats were examined during the course of liver restoration. Following hepatectomy, 33% of the liver mass observed in the sham operated group was present on day ), with approximately 50, 70, 75 and 82% present on days 2, 3, 4 and 7, respectively. Total restoration was noted by day 14. Plasma proteins abruptly decreased after hepatectomy and then gradually increased as liver mass was restored. The weights of both adrenal glands of hepatectomized animals were increased markedly on days 1 to 3, while adrenal corticosterone concentrations and production were elevated on day 2. Plasma corticosterone levels increased significantly following hepatectomy and remained elevated for 4 days, whereas only on the first day after surgery were the adrenal and plasma corticosterone levels elevated in the sham operated group. These data suggest that, despite the loss of liver mass and hence the apparent loss of delta 4-steroid hydrogenase activity, the adrenal glands do not decrease but actually increase their secretion during the first few days after hepatectomy.

[Immunological and structural properties of Rous sarcoma virus-transformed and tumor cells]

We compared the capacity of both normal and Rous sarcoma virus (RSV)-transformed chicken embryo fibroblast (CEF) cells as well as Rous sarcoma (RS) tumor cells to serve as targets in anti-tumor immunity assays. These studies showed that sera from tumor-bearing donors were able to stain transformed CEF more efficiently than RS cells as detected by immunofluorescence. In contrast, antiserum against the major viral glycoprotein, gp 85, stained a higher percentage of RS than transformed cells. Normal CEF cells, which served as controls, were essentially non-reactive with the immune system as judged by this type of assay. We observed that RS cells are considerably larger and contain far higher levels of protein than either normal or transformed CEF. Scanning electron microscopy revealed both the RS cells and transformed CEF to be rich in surface ruffles, blebs and microvilli as distinguished from the flattened, fusiform appearance of normal CEF cells.

Cellular and humoral anti-tumor immune responsiveness in chickens bearing tumors induced by avian sarcoma virus

A systematic comparison was undertaken of the respective abilities of normal chicken embryo fibroblast (CEF) cells, Rous sarcoma virus (RSV)- transformed CEF cells, avian Rous sarcoma (RS) tumor cells and murine RS cells to serve as targets and antigen donors in various assays for the detection of cellular and humoral anti-tumor immunity in chickens bearing tumors induced by Rous sarcoma virus. As measured by a cytotoxicity procedure, avian and murine RS cells were more susceptible to the killing effects of sensitized lymphocytes than were transformed CEF which in turn were more reactive than normal CEF. In contrast, sera from tumor-bearing animals were able to stain by indirect immunofluorescence only the avian RS and transformed CEF cell types. Extracts of both transformed CEF cells and avian RS cells but not normal CEF were equally effective as inhibitors of migration of peritoneal exudate cells derived from tumor-bearing animals. Transformed CEF were found to produce far higher quantities of transforming virus progeny than avian RS cells, although the latter were apparently albe to synthesize defective viral particles. These data indicate the significant variations which may occur under experimental conditions, depending on the types of assays and target cells employed.

Adrenocortical responses of rats to acute hypoxic and hypercapnic stresses after treatment with aminergic agents

Monoaminergic influences on the regulation of the hypothalamo-hypophyseal-adrenocortical (HHA) system during acute stresses (hypoxia and hypercapnia) were investigated in male rats. Plasma corticosterone levels were used to assess HHA activity, and the alterations in monoaminergic activity were induced by pretreating the animals with various pharmacologic agents (reserpine, alpha MT, FLA-63, pCPA, L-Dopa, pargyline, Lilly 110140, phentolamine and propranolol). Dexamethasone-treated rats were utilized to assess the site at which these monoaminergic substances acted. The latter experiments showed that these agents did not have a marked effect directly on the adrenal cortex and thus the site(s) of action was at the level of the anterior pituitary and/or above. Altering the serotoninergic system did not appreciably influence the HHA response to hypoxia and hypercapnia, whereas increasing the activity of the adrenergic system partially prevented the rise usually observed in plasma corticosterone levels during these stresses. These data suggest that different aminergic pathways may be utilized for different stresses.

Immunodeficiency to hepatitis B virus infection and genetic susceptibility to development of hepatocellular carcinoma

The high frequency of hepatitis B antigen (HBsAg) in hepatocellular carcinoma (HCC) patients has led to the hypothesis that immunoresponsiveness to hepatitis B virus (HBV) may be deficient in some patients, and that the immune response deficiency may have a genetic basis. Radioelectrocomplexing (REC), a radioimmunoassay in gel based on the principle of counterimmunoelectrophoresis (CIE), has been used to identify four HBV immune status subgroups: 1) HBsAg +ve/HBsAb +ve; 2) HBsAg +ve/HBsAb -ve; 3) HBsAb -ve/HBsAb +ve; 4) HBsAg -ve/HBsAb -ve/HBsAb -ve. These subgroups comprise 2, 6, 70, and 22 percent, respectively, among blood donors, and 32, 19, 23, and 26 percent, respectively, among HCC patients. Although the HBV exposure rates in the two groups were similar, the immune complexemic rates and HBs antigenemic rates were significantly higher in HBB patients than in the blood donors. It is proposed that the failure of termination of HBV infection revealed by these high rates reflects an immunodeficiency state characterized by an inability to produce high-avidity HBsAb. The immunodeficiency might have a primary genetic basis, or it might be secondary to the immunodepressive effects of concurrent viral or parasitic infections.

Optimal statistical design of radioimmunoassays and competitive protein-binding assays

The statistical analysis of radioimmunoassay and competitive protein binding assay data is complex. Because the response variable (percent counts) is not lineraly related to log dose, a logit transformation of the response variable usually is performed to permit linear regression analysis. This transformation induces marked heterogeneity of variance, so that iterative weighted regression programs have been used to achieve the best standard curve and the most precise dose estimates of unknowns. In this study several parameters of assay design are investigated in order to establish those designs yielding antigen concentration estimates of highest precision as well as estimates of comparable precision by either simple linear regression analysis or by the more complex weighted regression technique. Unknown estimates of highest precision are obtained when 1) the present counts of the standard doses covers a range of approximately 80 percent to 20 percent, 2) the number of standard dose levels is eight or more, 3) the number of replicates at each dose level is two or more, and 4) the percent counts of the unknowns also are within the range 80 percent ot 20 percent. Under these conditions, also, simple linear regression yields unknown estimates of comparable precision to weighted regression and therefore may be safely used.

Prevalence and site of bacteriuria in diabetes mellitus

Twenty-four of 152 female diabetic patients (15·8%) were found to have significant bacteriuria as compared to a prevalence rate of only 4·6% of 152 matched non-diabetic controls. The difference in prevalence rates is statistically significant. However, if the prevalence rates are analysed according to age, bacteriuria was significantly more common only in diabetic females above the age of 50. Localization of site of infection was performed in all diabetic female subjects with bacteriuria. The kidney was affected in 62·5% of patients. The pathogenetic considerations relating to these results are discussed. There was no difference in prevalence rate of bacteriuria between male diabetics and their controls.

Chronic liver disease: differences in autoimmune serological reactions between Australians and Asians

A total of 164 patients from Australia, Ceylon, India, Singapore, and Thailand were studied for the prevalence of autoantibodies associated with "idiopathic" chronic liver disease-namely, antinuclear antibody, smooth muscle antibody, and mitochondrial antibody. The prevalence of these autoantibodies was high among patients from Australia (55%), but was low among patients from Ceylon (14%), India (11%), Singapore (0%), and Thailand (8%). There are variations in types of hepatitis and cirrhosis between races, and this applies particularly to the type associated with autoimmune markers. This may be related to genetic differences that have evolved between peoples of European and Asian descent.

Polarography of conjugated unsaturated lipids

Conjugated fat-soluble vitamins, methylenic interrupted and conjugated fatty acids were polarographically investigated in both basic and neutral solvents. The half-wave potentials of all-trans-retinol, 13-cis-retinol, all-trans-retinyl acetate, all-trans-retinal, and Vitamin D(2) and D(3) were related to the number of double bonds in conjugation and their geometrical configuration. A minimum of three double bonds in conjugation and their geometrical configuration. A minimum of three double bonds in conjugation was required before reduction took place at the cathode, and as the number of conjugated bonds increased in the lipid compounds, the initial reduction wave took place at a lower half-wave potential.Investigation of conjugated double bonds in triglycerides and in alkali-isomerized linolenic and arachidonic acids gave reduction waves the half-wave potentials of which were related to the number of double bonds in conjugation. In both basic and neutral solvents there was a minimum of three double bonds in conjugation necessary to obtain a reduction wave at the dropping mercury electrode. Ultraviolet absorption curves of the prolonged reduction of polyunsaturated conjugated fatty acids indicate a step-wise reduction of each end of the polyunsaturated conjugated double bonds.In neutral solvent the log of the conjugated double bonds versus the half-wave potential (versus mercury pool anode) gave a linear equation, E(1)=2.98-1.6 log C. A proposed mechanism for the step-wise reduction of conjugated lipids is presented and discussed.