Ultrastructural study of the hemopoietic microenvironment in human fetal spleen

Reciprocal interactions between hemopoietic stromal cells and immature hemopoietic cells in human spleens obtained from 20 fetuses of 10-28 weeks gestation were observed by transmission electron microscopy and scanning electron microscopy. The close association of stromal cells with immature hemopoietic cells was confirmed under the electron microscope and a presumptive HIM (Hemopoietic inductive microenvironment) was visualized. In regions of immature hemopoietic cell-reticular cell, endothelial cell, macrophage and interdigitating cell contact, some communicating structures were found between the plasma membranes of adjacent cells; moreover, the cytoplasm of these four stromal cells were full of various kinds of organelles. These results suggest that reticular cells, endothelial cells, macrophages and interdigitating cells are component parts of the HIM of human fetal spleen and that these cells have a nurturing function in relation to hemopoietic cells.

Effects of sialoadenectomy and epidermal growth factor on testicular function of sexually mature male mice

The effect of sialoadenectomy (Sx) and epidermal growth factor (EGF) administration on testicular function was investigated in 8-week old C3H mice. Animals were divided initially into three groups: sham operated controls, Sx, and Sx + EGF treated (100 micrograms./kg./day subcutaneously for 28 days). Sialoadenectomy completely depleted the circulating levels of EGF and reduced body weight and reproductive organ weights. However, kidney weight was not affected. Quantitative analysis of spermatogenesis showed a decrease in preleptotene and pachytene spermatocytes and round spermatids, which resulted in a decrease in sperm counts. Sperm motility and fertility were also significantly decreased. Endocrinologic studies showed a 2- and 6-fold elevation in intratesticular and serum levels of testosterone and a decrease in luteinizing hormone (LH) levels. Follicle stimulating hormone levels were not altered. Administration of EGF to the Sx animals maintained reproductive organ weights, spermatogenesis and levels of LH and testosterone closer to control values; however, sperm motility was not maintained at control value. That sialoadenectomy resulted in a decline in androgen-dependent parameters, in spite of an elevation in testosterone levels, and EGF maintained them closer to the control value suggested that EGF may modulate androgen action. A comparison was therefore carried out between the effects of Sx and administration of flutamide (F), an androgen receptor blocker. Animals were subjected to Sx, F treatment (100 mg./kg./day subcutaneously for 28 days), Sx + F, or Sx + F + EGF. The effects of Sx and F treatment on organ weights, sperm counts and sperm motility were more or less similar. As expected, flutamide treatment increased LH and FSH levels, and testosterone levels were normal. The Sx + F animals showed no further decrease in organ weights, sperm count and motility. Treatment with Sx + F increased intratesticular and serum levels of testosterone by 2- and 10-fold. Circulating levels of LH and FSH were the same as in the flutamide-treated group. Administration of EGF to Sx + F maintained all these parameters, except sperm motility, closer to the control value. These results suggest that EGF either bypasses flutamide effects and acts directly or that EGF modulates androgen action at one or more steps in the signal transduction pathway in the male reproductive organs.

Exploration of requirements for peptide binding to HLA DRB1*0101 and DRB1*0401

The individual amino acid contacts responsible for peptide binding to DRB1*0101 and/or DRB1*0401 were defined using a quantitative binding assay. The differential contribution of each amino acid in two well studied T cell determinants, HA307-319 and RMBP 90-102, was delineated by comparing the IC50 values of analogues of varying length. This analysis confirmed the importance of a hydrophobic amino acid located near the amino-terminus for binding to both alleles and revealed that the contribution of the carboxyl-terminal amino acids differed between DRB1*0101 and DRB1*0401. Taking advantage of previous experiments demonstrating that all of the residues could be replaced with alanine, with the exception of the key hydrophobic amino acid, simplified analogues composed of polyalanines were used to prove 1) optimal binding depended on the position of the hydrophobic side chain relative to the amino- and carboxyl-termini; 2) aromatic amino acids were superior to aliphatic side chains at this position; and 3) a significant amount of free energy of binding arises from hydrogen bonding between the class II binding site and the amide bonds of the ligand. The role of each carbonyl and amide nitrogen was measured by assaying analogues containing reduced peptide bonds or N-methyl amino acids. Serine, but not glycine, could be used as a framework amino acid for peptide ligands, indicating that the beneficial aspects of these simplified structures was the combination of retaining the correct orientation of the peptide bonds, the restriction of the conformational freedom by limiting the possible phi/psi angles of the peptide, and avoidance of deleterious side-chain contacts. Collectively, these data were consistent with the peptide binding in a nonrepeating conformation with the vast majority of the free energy of binding arising from hydrogen bonds with the peptide backbone and a single, key hydrophobic side chain interacting in a conserved pocket in both DRB1*0101 and DRB1*0401.

Exploration of requirements for peptide binding to HLA DRB1*0101 and DRB1*0401

The individual amino acid contacts responsible for peptide binding to DRB1*0101 and/or DRB1*0401 were defined using a quantitative binding assay. The differential contribution of each amino acid in two well studied T cell determinants, HA307-319 and RMBP 90-102, was delineated by comparing the IC50 values of analogues of varying length. This analysis confirmed the importance of a hydrophobic amino acid located near the amino-terminus for binding to both alleles and revealed that the contribution of the carboxyl-terminal amino acids differed between DRB1*0101 and DRB1*0401. Taking advantage of previous experiments demonstrating that all of the residues could be replaced with alanine, with the exception of the key hydrophobic amino acid, simplified analogues composed of polyalanines were used to prove 1) optimal binding depended on the position of the hydrophobic side chain relative to the amino- and carboxyl-termini; 2) aromatic amino acids were superior to aliphatic side chains at this position; and 3) a significant amount of free energy of binding arises from hydrogen bonding between the class II binding site and the amide bonds of the ligand. The role of each carbonyl and amide nitrogen was measured by assaying analogues containing reduced peptide bonds or N-methyl amino acids. Serine, but not glycine, could be used as a framework amino acid for peptide ligands, indicating that the beneficial aspects of these simplified structures was the combination of retaining the correct orientation of the peptide bonds, the restriction of the conformational freedom by limiting the possible phi/psi angles of the peptide, and avoidance of deleterious side-chain contacts. Collectively, these data were consistent with the peptide binding in a nonrepeating conformation with the vast majority of the free energy of binding arising from hydrogen bonds with the peptide backbone and a single, key hydrophobic side chain interacting in a conserved pocket in both DRB1*0101 and DRB1*0401.

Progress in mapping human epilepsy genes

The chromosomal loci for seven epilepsy genes have been identified in chromosomes 1q, 6p, 8q, 16p, 20q, 21q, and 22q. In 1987, the first epilepsy locus was mapped in a common benign idiopathic generalized epilepsy syndrome, juvenile myoclonic epilepsy (JME). Properdin factor or Bf, human leukocyte antigen (HLA), and DNA markers in the HLA-DQ region were genetically linked to JME and the locus, named EJM1, was assigned to the short arm of chromosome 6. Our latest studies, as well as those by Whitehouse et al., show that not all families with JME have their genetic locus in chromosome 6p, and that childhood absence epilepsy does not map to the same EJM1 locus. Recent results, therefore, favor genetic heterogeneity for JME and for the common idiopathic generalized epilepsies. Heterogeneity also exists in benign familial neonatal convulsions, a rare form of idiopathic generalized epilepsy. Two loci are now recognized; one in chromosome 20q (EBN1) and another in chromosome 8q. Heterogeneity also exists for the broad group of debilitating and often fatal progressive myoclonus epilepsies (PME). The gene locus (EPM1) for both the Baltic and Mediterranean types of PME or Unverricht-Lundborg disease is the same and is located in the long arm of chromosome 21. Lafora type of PME does not map to the same EPM1 locus in chromosome 21. PME can be caused by the juvenile type of Gaucher's disease, which maps to chromosome 1q, by the juvenile type of neuronal ceroid lipofuscinoses (CLN3), which maps to chromosome 16p, and by the "cherry-red-spot-myoclonus" syndrome of Guazzi or sialidosis type I, which has been localized to chromosome 10. A point mutation in the mitochondrial tRNA(Lys) coding gene can also cause PME in children and adults (MERFF).

The synthesis of 7 alpha-methyl-substituted estrogens labeled with fluorine-18: potential breast tumor imaging agents

The 7 alpha-methyl substituent is reported to increase the binding affinity of estradiol for the estrogen receptor (ER). In order to evaluate whether this substituent would improve the in vitro binding characteristics and the in vivo tissue distribution of 18F labeled estrogens that we are developing as positron emission tomographic (PET) imaging agents for ER-positive breast tumors, we have prepared four 18F labeled analogs of 7 alpha-methylestradiol. These ligands were labeled in the 16 alpha or 16 beta position with 18F by nucleophilic displacement of the corresponding epimeric estrone trifluoromethanesulfonates with 18F fluoride ion. Lithium aluminum hydride reduction afforded the estradiol (E2) series, while lithium trimethylsilylacetylide addition provided the 17 alpha-ethynylestradiol (EE2) series. The decay-corrected yields were 2-35% for a synthesis time of 85 minutes for the E2 series, and 120 minutes for the EE2 series, and the effective specific activities were 158-1213 Ci/mmol. In nearly every case, the 7 alpha-methyl substituent increases ER binding affinity (measured at 25 C) and decreases binding to high affinity serum steroid binding proteins, alphafetoprotein, and sex steroid binding protein; this substituent, however, increases the lipophilicity and the predicted non-specific binding (estimated from octanol-water partition coefficients determined by reverse-phase high-pressure liquid chromatography/[HPLC]), with the result that the ratio of ER binding to non-specific binding is nearly the same for the 7 alpha-methyl substituted analogs as for the corresponding unsubstituted analogs. In vivo distribution studies demonstrated a high level of receptor-mediated uptake in receptor-rich target tissues (uterus, ovaries), and in some cases, other tissues with low ER titers (secondary target tissues, e.g., muscle, thymus) showed significant displaceable uptake, presumed to be receptor-mediated.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular basis for the inhibition of human alpha-thrombin by the macrocyclic peptide cyclotheonamide A

The macrocyclic peptide cyclotheonamide A (CtA), isolated from the marine sponge Theonella sp., represents an unusual class of serine protease inhibitor. A complex of this inhibitor with human alpha-thrombin, a protease central to the bioregulation of thrombosis and hemostasis, was studied by x-ray crystallography. This work (2.3-A resolution) confirms the structure of CtA and reveals intimate details about its molecular recognition within the enzyme active site. Interactions due to the "Pro-Arg motif" (Arg occupancy of the S1 specificity pocket; formation of a hydrogen-bonded two-strand antiparallel beta-sheet with Ser214-Gly216) and the alpha-keto amide group of CtA are primarily responsible for binding to thrombin, with the alpha-keto amide serving as a transition-state analogue. A special interaction with the "insertion loop" of thrombin (Tyr60A-Thr60I) is manifested through engagement of the hydroxyphenyl group of CtA with Trp60D as part of an "aromatic stacking chain." Biochemical inhibition data (Ki values at 37 degrees C) were obtained for CtA with thrombin and a diverse collection of serine proteases. Thus, CtA is just a moderate inhibitor of human alpha-thrombin (Ki = 0.18 microM) but a potent inhibitor of trypsin (Ki = 0.023 microM) and streptokinase (Ki = 0.035 microM). The relative lack of potency of CtA as a thrombin inhibitor is discussed with respect to certain structural features of the enzyme complex. We also report the total synthesis of CtA, by a convergent [2 + 3] fragment-condensation approach, to serve the preparation of cyclotheonamide analogues for structure-function studies.

[A clinical study on the effect of non-adrenergic non-cholinergic nerves in asthma]

Non-adrenergic non-cholinergic (NANC) nerves are the third nervous system in the lung. There are increasing evidences that the main transmitters of NANC inhibitory (NANC-i) nerves and NANC excitatory (NANC-e) nerves are vasoactive intestinal peptide (VIP) and substance P (SP) respectively. We measured the levels of plasma VIP. SP and bronchial responsiveness in the patients with asthma. Chronic bronchitis and healthy subjects. The results showed that VIP level is decreased and negatively correlated with airway resistance, whereas SP level is increased and positively correlated with bronchial hyperresponsiveness (BHR) in asthma. It is suggested that overexcitation of NANC-e nerves and deficiency of NANC-i nerves are closely related with asthma attack and BHR.

[A clinical study on determination of plasma vasoactive intestinal peptide and the relationship between plasma vasoactive intestinal peptide and bronchial responsiveness in asthmatics]

Vasoactive intestinal peptide (VIP), which is localized in normal human lung, may play an important role in regulating bronchial tone, pulmonary blood flow and mucus secretion. The level of plasma VIP and bronchial responsiveness were studied in patients with asthma, chronic bronchitis and the healthy subjects. The results showed that the level of plasma VIP in asthmatic patients during acute attack and symptom-free period was significantly lower than that in the patients with bronchitis and the healthy subjects and it is negatively correlated with the bronchial hyperresponsiveness. It is suggested that both asthmatic attack and bronchial tone are related with the decrease of VIP.

[Mitochondrial DNA polymorphism of cattle (Bos taurus) and mithun (Bos frontalis) in Yunnan Province]

An analysis of cleavage patterns of mtDNA by restriction endonuclease was performed for fifteen Yunnan native cattle, two Kunming black and white cow, and one mithun (Bos frontalis). Two types of mtDNA molecule were detected in Yunnan native cattle: five individuals showed the type of yellow cattle (Bos taurus), the other ten showed that of zebu cattle (Bos indicus), suggesting their European and zebu origins. The mtDNA in Kunming black and white cow also consists of two restriction types. The mithun mtDNA showed the type of zebu cattle, indicating the close relationship between the origins of mithun and zebu cattle.

Amelioration of autoimmune encephalomyelitis by myelin basic protein synthetic peptide-induced anergy

Experimental autoimmune encephalomyelitis (EAE), a demyelinating disease of the central nervous system that can be induced in susceptible strains of mice by immunization with myelin basic protein (MBP) or its immunodominant T cell determinants, serves as a model of human multiple sclerosis. Tolerance to MBP in adult mice was induced by intraperitoneal injection of synthetic peptides of immunodominant determinants of MBP and prevented MBP-induced EAE. Furthermore, tolerance-inducing regimens of peptides administered to mice after the disease had begun (10 days after induction with MBP) blocked the progression and decreased the severity of EAE. Peptide-induced tolerance resulted from the induction of anergy in proliferative, antigen-specific T cells.

Epidermal growth factor: receptor binding and effects on the sex accessory organs of sexually mature male mice

The role of epidermal growth factor (EGF) in maintaining the integrity of the male sex accessory glands was investigated in the mouse. In the sexually mature male C3H mouse, EGF levels were highest in the submandibular gland, followed by the seminal vesicles and the prostate. Twenty eight days after sialoadenectomy (Sx), EGF fell below detectable limits in the serum and in the seminal vesicles. However, the prostate still retained 22% of its immunoreactive EGF. There was a seven-fold increase in serum testosterone after sialoadenectomy. Despite this drastic rise in testosterone, both prostatic and seminal vesicular weights were reduced, serum levels of LH were suppressed only by 37% and FSH levels were not altered. All these changes were abolished by the simultaneous administration of exogenous EGF at 100 micrograms./kg./day for 28 days. Both prostatic and seminal vesicular membranes contained binding sites for 125I-EGF. Binding was maximal after one hour of incubation at room temperature. Two classes of binding sites were shown for either organ (Kd = 1.2 nM, n = 56 fmol/mg. and Kd = 74 nM, n = 540 fmol/mg. for prostate; Kd = 0.9 nM, n = 29 fmol/mg. and Kd = 93 nM, n = 150 fmol/mg. for seminal vesicle). The binding of 125I-EGF was displaced by excess EGF and TGF-alpha but not by insulin, ILGF-2 and PDGF. These data suggest that EGF may have an important role in maintaining the integrity of the seminal vesicle and the prostate in the mouse. While the seminal vesicle appears to acquire EGF by uptake from the environment, the prostate may have the ability to synthesize EGF locally.

A comparison of herpes simplex virus specific antibodies found in human milk and serum

It is not known if milk antibody protects infants from herpes simplex virus (HSV) infection. As a first step to test this hypothesis, anti-HSV antibodies were studied in human milk. Paired serum and milk samples were analyzed for anti-HSV antibodies by ELISA, Western blot analysis (WBA), neutralization (NT) plaque assay, and antibody-dependent cellular cytotoxicity (ADCC) assay. Nineteen of the 20 serum samples showed anti-HSV activity by ELISA and ADCC, and 18 showed activity by WBA and NT. We found a significant association between the immunoassays for detection of anti-HSV antibodies in sera. Fewer of the human milk samples showed anti-HSV activity; only one milk sample was positive by ELISA and one by NT assay, four by ADCC and 12 by WBA. The milk sample from the seronegative donor was also negative. We found a poor association of antibody titers in human milk and serum antibody titers using ELISA, NT, and ADCC assays. There was a significant (p = 0.022) association between serum and milk results using WBA. Among the four assays, WBA was the most sensitive for antibody detection. It will be used in an on-going prospective study to determine the role of anti-HSV antibody in the protection against HSV infections in infants.

Synthesis of high affinity fluorine-substituted ligands for the androgen receptor. Potential agents for imaging prostatic cancer by positron emission tomography

We have prepared nine androgens substituted with fluorine at C-16 or C-20 to evaluate their potential, as positron emission tomographic (PET) imaging agents for prostatic cancer when labeled with the positron emitting radionuclide fluorine-18 (t1/2 = 110 min). These compounds represent members from the following classes of androgens: testosterone (T), 5 alpha-dihydrotestosterone (DHT), 7 alpha-methyl-19-nortestosterone (MNT), mibolerone (Mib), and metribolone (R1881). All of these compounds were prepared by functionalization of suitable androgen precursors, and the synthetic routes were developed to allow the introduction of fluorine by a fluoride ion displacement reaction late in the synthesis, as is required for the preparation of these compounds in fluorine-18 labeled form. We have also prepared four androgens in which the C-3 carbonyl or 17 beta-hydroxyl groups are replaced by fluorine. Most of the fluorine-substituted androgens show high affinity for the androgen receptor (AR), although fluorine substitution lowers their affinity by a small factor. None of the androgens where fluorine replaces oxygen functions at C-3 or C-17 have substantial affinity for AR. Derivatives of the natural androgens (T and DHT) as well as MNT have little affinity for other steroid hormone receptors (progesterone and mineralocorticoid receptors), whereas the Mib and R1881 derivatives have somewhat greater heterologous binding. With sex steroid binding protein, a human serum binding protein, the pattern of binding affinities is nearly the reverse, with derivatives of Mib, R1881 and MNT having low affinity, and DHT and T, high affinity. From these fluorine-substituted compounds, we can select several whose preparation in fluorine-18 labeled form for further tissue distribution studies is merited.

Fluorine-18-labeled androgens: radiochemical synthesis and tissue distribution studies on six fluorine-substituted androgens, potential imaging agents for prostatic cancer

We have synthesized six androgens labeled with 18F as potential imaging agents for prostatic cancer. These include 16 beta-fluorine-substituted testosterone, dihydrotestosterone and mibolerone, 16 alpha- and 16 beta-fluorine substituted 7 alpha-methyl-19-nortestosterone, and 20-fluoro-R1881 (metribolone). All of the radiochemical preparations proceeded in satisfactory yield, giving material with adequately high effective specific activity for the in vivo studies. In the tissue distribution studies in diethylstilbestrol-treated male rats, high selective uptake by the prostate was observed that ranged from 0.39% to 1.21% injected dose (ID)/g at 1 hr and 0.20 to 0.47 at 4 hr, with prostate-to-blood and prostate-to-muscle ratios ranging from 3.28 to 9.45, respectively, at 1 hr and 4.06 to 35.0, respectively, at 4 hr. Those compounds that are likely to be metabolized rapidly showed lower prostate uptake but higher uptake selectivity at 4 hr; at earlier times, uptake selectivities were more comparable. Compounds with a 16 beta-fluorine substituent showed extensive metabolic defluorination, resulting in ca. 50% of the dose being deposited in bone at 4 hr. This is consistent with a 16 alpha-hydroxylation process that may proceed rapidly with these compounds, but would be retarded by a 17 alpha-methylation, blocked by inversion of stereochemistry at C-16, and would not affect fluorine at the C-20 position. These fluoroandrogens, together with 20-fluoromibolerone described previously, are the first positron-emitting androgens to show high affinity and selective uptake by androgen target tissues in vivo, and they may be useful as in vivo prostate imaging agents in man.

Detection of neonatal seizures through computerized EEG analysis

Neonatal seizures are a symptom of central nervous system disturbances. Neonatal seizures may be identified by direct clinical observation by the majority of electrographic seizures are clinically silent or subtle. Electrographic seizures in the newborn consist of periodic or rhythmic discharges that are distinctively different from normal background cerebral activity. Utilizing these differences, we have developed a technique to identify electrographic seizure activity. In this study, autocorrelation analysis was used to distinguish seizures from background electrocerebral activity. Autocorrelation data were scored to quantify the periodicity using a newly developed scoring system. This method, Scored Autocorrelation Moment (SAM) analysis, successfully distinguished epochs of EEGs with seizures from those without (N = 117 epochs, 58 with seizure and 59 without). SAM analysis showed a sensitivity of 84% and a specificity of 98%. SAM analysis of EEG may provide a method for monitoring electrographic seizures in high-risk newborns.