Biomedical subjects
Publications and source records attributed to J E Robinson.
Synthesis of 5R-Acetamido-4S-amino-4H-pyran-6R-O-( -ethyl)propyl and 6R-(1-oxo-2-ethyl)butyl 2-carboxylic acids (4 and 5) and their evaluation as inhibitors of influenza virus sialidase is described. Both compounds showed good inhibitory activity with marked selectivity for influenza A sialidase.
In our search for new, safer anti-HCMV agents, we discovered that the natural product Arcyriaflavin A (la) was a potent inhibitor of HCMV replication in cell culture. A series of analogues (symmetrical indolocarbazoles) was synthesised to investigate structure activity relationships in this series against a range of herpes viruses (HCMV, VZV, HSV1, and 2). This identified a number of novel, selective and potent inhibitors of HCMV, 12,13-dihydro-2,10-difluoro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazol e-5,7-(6H)-dione (1d) being the best example (IC50=40 nM, therapeutic index > 1450). Compounds described in this series were generally poor inhibitors of protein kinase C betaII, and no correlation was found between the ability to inhibit HCMV and the enzyme PKC.
Thirty codependent cocaine and alcohol users were compared with age-, education-, race-, and sex-matched cocaine abusers (N = 30) and normals (N = 30) using an extended Halstead-Reitan Neuropsychological Test Battery to determine whether cocaine abusers with alcohol dependence were more cognitively impaired than singly addicted cocaine abusers. Tests were grouped and analyzed according to 8 major ability areas. Participants who abused both cocaine and alcohol did not differ from normals on the majority of test measures. An unexpected but consistent finding was the poorer performance of the cocaine sample relative to cocaine and alcohol abusers on measures of complex psychomotor and simple motor functioning (ps < .001). Pure cocaine abusers, but not abusers of both cocaine and alcohol, also performed more poorly than normals on a measure of global neuropsychological functioning (p < .01). These results are consistent with previous reports of generally mild cognitive dysfunction in cocaine abusers. The findings also suggest that cocaine and alcohol abusers of relatively young ages may be less cognitively impaired than demographically comparable cocaine abusers. Evidence from studies of vascular functioning in abusers of cocaine and alcohol alone and in combination is discussed as possible explanation for these findings.
Rey-Osterrieth Complex Figure (ROCF) productions from 18 adults with Attention Deficit Hyperactivity Disorder (ADHD) were compared to 18 matched controls using the Boston Qualitative Scoring System (BQSS). ADHD adults showed impairment in measures of configural accuracy, planning, and neatness. A logistic regression model resulted in 75% sensitivity and 81% specificity in discriminating ADHD from control subjects. In contrast, there was no significant difference on the traditional ROCF 36-point score, and the sensitivity and specificity for the 36-point score were lower (68% and 71%, respectively). These findings suggest persisting executive dysfunction in adults with ADHD that can be detected in ROCF productions. Thus, the BQSS may be a useful tool contributing to the neuropsychological evaluation of adults with ADHD.
Exposure of the female ovine fetus to exogenous androgens during early gestation permanently masculinizes the reproductive anatomy, physiology, and behavior of the adult ewe. In utero testosterone exposure has been shown to act centrally on the GnRH neuronal network to alter the response to both the stimulatory and inhibitory actions of estrogen. It is currently unknown whether fetal androgens alter other mechanisms that are critical for the regulation of GnRH release and, specifically, other important regulatory steroid feedback loops. Three studies were performed on gonadectomized postpubertal sheep to determine whether the inhibitory actions of progesterone on episodic LH release are also sex-specific and engendered by early in utero exposure to testosterone. In each study, the pulsatile pattern of LH release was determined both before and after the sc implantation of a progesterone releasing CIDR device. The studies involved 7 female, 7 male, and 12 androgenized female sheep (T60 (n = 7) and T30 (n = 5) groups; 200 mg testosterone propionate/week im to the mother for 60 or 30 days, respectively, from day 30-90 or 60-90 of pregnancy). The first two studies were performed in the anestrous season in the presence (Exp 1) or absence (Exp 2) of a low circulating concentration of estradiol. Exp 3 was carried out in the breeding season in the absence of exogenous estrogen. In all three studies progesterone inhibited LH pulse frequency only in the females. Progesterone had no action on mean LH concentrations or the frequency or amplitude of LH pulses in the males or either group of androgenized ewes. We conclude that the inhibition of episodic LH release by progesterone is sexually differentiated in the sheep, males being less responsive than females to steroid negative feedback. Further, these sex differences are a consequence of in utero exposure to androgens for a period as short as 30 days between days 60 and 90 of a 147-day pregnancy.
The preovulatory GnRH/LH surge in the ewe is stimulated by a rise in the circulating estradiol concentration that occurs in conjunction with preovulatory ovarian follicle development. In the presence of high levels of progesterone, such as during the luteal phase of the estrous/menstrual cycle, the stimulatory effects of elevated estradiol on GnRH/LH secretion are blocked. Recent work in the ewe has shown that a relatively short period of estradiol exposure can stimulate a GnRH/LH surge that begins after estrogenic support has been removed. This result suggests that surge generation is characterized by an estradiol-dependent period (during which the signal is read) and an estradiol-independent period (during which a cascade of neuronal events transmits the stimulatory signal to the GnRH neurosecretory system, which releases a surge of GnRH). In this series of studies, we addressed the hypothesis that progesterone can block transmission of the stimulatory estradiol signal after it has been read. Nine ovariectomized ewes were run through repeated artificial estrous cycles by sequential addition and removal of exogenous steroids. In study one, ewes received three treatments in a randomized cross-over design. Exposure to a follicular phase estradiol concentration for 10 h (positive control treatment) stimulated an LH surge in all ewes, as determined in hourly jugular blood samples. Maintenance of luteal phase progesterone concentrations throughout the artificial follicular phase (2 x CIDR-G devices, negative control) blocked the stimulatory effects of a 10-h estradiol signal, and no ewes that received this treatment expressed an LH surge. In the experimental group, exposure to luteal phase levels of progesterone, during the period after the surge generating system had been activated by estradiol, blocked the LH surge in six of nine ewes. This result demonstrates that progesterone can block the surge, even when applied after the surge-generating system has been activated and, therefore, that it inhibits either the transmission of the estradiol signal and/or the release of the GnRH/LH surge. In study 2, we assessed whether sensitivity to the inhibitory effects of progesterone was confined to a specific stage of the transmission of the estradiol signal. Eight ewes were exposed to four treatments, over successive artificial estrous cycles. Positive and negative controls were similar to those described in Study 1, except the duration of the stimulatory estradiol signal was reduced to 8 h. The two experimental groups consisted of an EARLY P (progesterone) treatment, in which progesterone was given from hours 8-13 after estradiol insertion (immediately after estradiol removal), and a LATE P treatment, in which progesterone was given from hours 13-18 (immediately before LH surge secretion). As expected, LH surges were stimulated and blocked, in response to the positive and negative controls, respectively. Whereas the EARLY P treatment blocked the LH surge in seven of eight ewes, the LATE P treatment was only successful in inhibiting a surge in one of eight animals. This result demonstrates that progesterone can block the estradiol-induced surge-generating signal soon after the onset of signal transmission (immediately after estradiol removal) but not during the later stages of signal transmission (at the time of GnRH/LH surge onset).
Five rhesus monoclonal antibodies (RhMAbs) were produced by rhesus EBV transformation of peripheral blood B cells from a rhesus macaque that had been asymptomatically infected with an attenuated, macrophage-tropic SIV strain, 17E-Cl. These MAbs recognized conformation-dependent epitopes on SIV gp120 and could not be mapped using synthetic peptides. All five RhMAbs were able to neutralize the vaccine strain and a heterologous isolate, SIV/DeltaB670. The RhMAbs did not cross-react with HIV-2; by contrast, four human MAbs derived from an HIV-2-infected person were broadly cross-reactive with both SIV and HIV-2 gp120s. Cross-competition analysis indicated that the five RhMAbs could be placed in two groups recognizing two nonoverlapping epitopes; while the HMAbs were placed in two additional competition groups. Binding of the three group I RhMAbs (1.7F, 3.11B, and 1.10A) as well as HMAb 17A was shown to be sensitive to specific amino acid alterations in V4 occurring in natural env variants. The results of this study demonstrate that RhEBV transformation provides a means to probe rhesus antibody responses to SIV infection at the monoclonal level. RhMAbs will allow structural and functional studies of envelope glycoprotein determinants that elicit protective immune responses against SIV.
The preovulatory LH surge in the ewe is stimulated by the massive and sustained release of GnRH into the pituitary portal vessels. This study has examined the temporal relationship between changes in LH secretion and GnRH messenger RNA (mRNA) expression at the time of the estradiol-induced LH surge. Ovariectomized Clun Forest ewes were treated with exogenous progesterone and estradiol (E) to mimic estrous cycle concentrations of these gonadal steroids and to induce the LH surge. Ewes were killed at five time points relative to the time of onset of the LH surge: pre-E, before E insertion (n = 6); presurge, after E insertion and 8-10 h before surge onset (n = 5); ascending limb, 2-6 h after surge onset (n = 5); midpeak, 9-12 h after surge onset (n = 5); and postsurge, 21-27 h after surge onset (n = 5). Control animals (n = 5/group), which received no E, were killed at identical time intervals alongside the E-treated ewes. Coronal sections containing the diagonal band of Broca through to the anterior hypothalamus were processed for cellular in situ hybridization using an 35S-labeled oligonucleotide probe complementary to ovine GnRH. No changes were found in the number of GnRH mRNA-expressing cells detected in the rostral preoptic area or the medial septum in either gonadal steroid-treated or control ewes. In contrast, cellular GnRH mRNA expression (as assessed by silver grain density) decreased significantly (P < 0.05) between presurge and ascending limb groups within both the rostral preoptic area (0.64 +/- 0.06 vs. 0.43 +/- 0.05 silver grain density/microm2) and medial septum cells (1.08 +/- 0.09 vs. 0.77 +/- 0.07). No significant changes were detected in control ewes. These results show that the estradiol-induced LH surge in the ewe is associated with a decrease in GnRH mRNA expression that occurs in advance of the onset of the GnRH surge. This suggests that neural mechanisms controlling GnRH biosynthesis may be distinct from those regulating GnRH secretion.
In the fall of 1997, the Idaho Commission of Nursing and Nursing Education undertook a survey of Idaho nurses to collect data on future workforce and educational needs. The results of the survey demonstrated substantial attitudinal differences between licensed practical nurses and registered nurses in the areas of educational motivation, role differentiation, skills by type of nurse, trends in nursing supply, and educational preparation. Given that the Idaho workforce is comparable to the national nursing workforce in numbers, educational background, and age, these findings have implications for health policy planners and nursing educators throughout the country. This article presents the findings and then uses the data as a basis for suggesting their implications for nursing education and workforce planning.
The distribution and morphology of luteinising hormone-releasing hormone (LHRH) neurones varies between species. The primary purpose of this study was to characterize the distribution and morphology of the LHRH system in a species of antelope, the springbok. This wild antelope has a well-defined social structure in which reproductive activity is confined to a few dominant, territorial rams. We also sought to determine whether social or reproductive status could be accounted for by differences in the distribution or morphology of hypothalamic LHRH neurones. Eleven anoestrous female, nine breeding territorial male (TM) and eight "bachelor" male (BM) springbok were obtained, and their reproductive and body conditions were assessed. By using standard immunocytochemical techniques, the LHRH system was visualised in the brains of four animals from each group. Immunoreactive neurones were located in a continuum from the septum to the arcuate nucleus, with the majority at the level of the organum vasculosum of the lamina terminalis. Neither the distribution nor the number of cells differed among the three groups. Furthermore, the area of LHRH perikarya was similar in both groups of males, suggesting that reproductive differences between TMs and BMs lie at another level of the neuroendocrine axis. The anoestrous females had significantly larger neurones than males (TM plus BM). This may reflect a sex difference in the LHRH system of this wild antelope. However, an alternative explanation is that the male/female difference is related to the comparatively inactive reproductive neuroendocrine state of the females.
A phage display library screening approach was used to identify peptide sequences that could bind to anti-HIV-1 MAbs whose binding specificities are complex. Most of the antibodies used recognize discontinuous epitopes in gp120 and one recognizes gp41. Both a 15-mer and a 21-mer display library (each with a complexity of greater than 60 x 10[6]) and two constrained, V3 region-biased libraries, all expressed as recombinant pIII protein of filamentous phage, were used. The unmapped anti-gp120 human MAb A32 recognized a set of related linear sequences and repeatedly identified a single phage sequence that could form a cyclic disulfide structure. Selection methods were also developed so that phage could be obtained by competition selection in the presence of antibody bound to native, monomeric gp120 antigen (used with MAb IgG1b12 and the anti-gp120 V3 region MAb 447-52D) or gp120 variable region 3 synthetic peptides (used with anti-gp120 V3 region MAb 19b). The potent, virus-neutralizing MAb IgG1b12 recognized numerous sequences and, when used in competition with gp120, recognized only one sequence. These studies extend the range of antibody determinant studies that can be performed with display phage libraries, demonstrate a workable experimental strategy for use of competition ligands to discriminate among phage mimotopes, and provide a large number of mimotopes that bind potent virus-neutralizing MAbs for HIV-1 vaccine studies.
To test whether antibodies that are neutralizing or nonneutralizing for human immunodeficiency virus type 1 (HIV-1) primary isolates can be distinguished by their affinities for the oligomeric envelope glycoproteins, we selected HIV-1(JR-FL) as a model primary virus and a panel of 13 human monoclonal antibodies (MAbs) and evaluated three parameters: (i) half-maximal binding to recombinant monomeric envelope, gp120(JR-FL); (ii) half-maximal binding to oligomeric envelope of HIV-1(JR-FL) expressed on the surface of transfected 293 cells; and (iii) neutralization of HIV-1(JR-FL) in a peripheral blood mononuclear cell-based neutralization assay. Two conclusions can be drawn from these experiments. First, we confirm that antibody interactions with monomeric gp120 do not predict primary virus neutralization. Second, we show that neutralization correlates qualitatively with the relative affinity of an antibody for the oligomeric envelope glycoproteins, at least for HIV-1(JR-FL).
It is not known where melatonin acts to influence the neuroendocrine axis of seasonally breeding mammals. However, since the pars tuberalis (PT) contains the highest density of melatonin receptors, this adenohypophyseal subdivision is a potential target. Gonadotropes are the only immunocytochemically detectable adenohypophyseal cell type of abundance in the PT. This study investigated whether melatonin could modulate basal and/or gonadotropin-releasing hormone (GnRH)-stimulated luteinising hormone (LH) secretion from the ovine PT and pars distalis (PD) in vitro. Tissue fragments from both pituitary areas were placed in separate chambers in a constant-environment perifusion system (37 degrees C; 100 microl/min) and 10-min effluent fractions were collected, frozen and later assayed for LH. Sixty minutes prior to a GnRH challenge (10 min; 10 nM), melatonin (1 microM or 100 nM) was added to the perifusate of half the tissue fragments. GnRH increased (p < 0.01) LH output from both pituitary subdivisions. Melatonin attenuated (p < 0.05) the GnRH-induced increase in LH output from the PT but not from the PD. The physiological importance of this melatonin-attenuated PT LH is unknown but it may play a role in modulating the neuroendocrine reproductive axis.
This study replicated the two Minnesota Multiphasic Personality Inventory subtypes (psychopathic and severe psychiatric) found in inpatient male cocaine abusers in an outpatient sample of 132 men and women. The Addiction Severity Index validated these subtype differences on the basis of psychiatric severity.
The binding properties of six indolocarbazole derivative have been measured using immobilised human serum albumin (HSA) in an HPLC column. The compounds showed very strong binding to HSA which necessitated the application of a 30 to 40% concentration of 2-propanol in the mobile phase. This represents a much higher concentration than is recommended by the column manufacturers. This HSA column had not changed its binding property when it was used again with 4% 2-propanol and 96% phosphate buffer. The binding parameters were estimated by extrapolation to 0% 2-propanol and were above 99% for each indolocarbazole derivative. The correlation analysis, including the calculated octanol/water partition coefficient (log P), pKa values as well as measured reversed-phase retention data of the compounds revealed that the extremely strong binding can be explained by the hydrophobic and acidic properties of the compounds.
The role of urinary toxins in interstitial cystitis (IC) has been suggested. This report describes the partial purification of a substance from human urine that inhibited in vitro colony formation by mouse fibroblasts. Urine samples from 15 women with IC and 17 healthy women serving as volunteers were fractioned by ultrafiltration and chromatography methods and tested by the inhibition of Swiss 3T3 fibroblast colony formation. The fibroblasts were cultured at low density with varying concentrations of whole or fractioned urine. Colonies were counted at 10 days. Colony formation was reduced by incubation with whole urine, ultrafiltrate, and nonadsorbed C18 fractions. Inhibition of colony formation by urine from healthy volunteers or women with IC was not significantly different. In vitro colony formation by Swiss 3T3 cells was inhibited by a component of human urine. The toxicity of urine from IC patients was not different from that of urine from healthy controls.
This study investigated whether season or long-term ovariectomy influence the presence, distribution and density of immunoreactive cells in the ovine pars tuberalis. Three groups of ewes were used: breeding season (BS; n=5), anoestrous (AS; n=8) and ovariectomised (OVX; n=4). Two rams were also investigated for possible sex-dependent differences. Employing standard immunocytochemical techniques, paraformaldehyde-fixed sagittal pars tuberalis and pars distalis sections were immunoreacted against luteinising hormone, luteinising hormone beta-subunit, thyroid-stimulating hormone, prolactin, growth hormone, beta-endorphin and adrenocorticotrophic hormone. Numerous gonadotrophs were detected in the anteroventral region of the pars tuberalis and there was no significant difference in the density (gonadotrophs/0.01 mm2; BS: 44+/-13, AS: 29+/-2, OVX: 27+/-4) or percentage of total cells (%; BS: 48+/-8, AS: 45+/-4, OVX: 49+/-2); the rams also appeared similar (27+/-2 gonadotrophs/0.01 mm2; 49+/-1%). In contrast, few gonadotrophs (less than 1%) were detected in the anterodorsal and posterior pars tuberalis regions. Apart from occasional thyrotrophs in the anteroventral pars tuberalis (less than 4%), no other pars distalis hormone-containing cells were detected in the pars tuberalis. This study demonstrates, therefore, that the anteroventral pars tuberalis represents an enriched population of immunoreactive gonadotrophs, whose number and distribution is similar in variable endocrine states. The protein phenotype(s) of cells in the other pars tuberalis regions remains undetermined.
Testosterone exerts important feedback effects on the hypothalamus of the ram to influence reproductive functioning. To provide a neuroanatomical basis for understanding this androgen action, the present study has examined androgen receptor (AR) immunoreactivity within the hypothalamus and adjacent brain areas of the intact non-breeding season ram. The largest populations of AR-immunoreactive cells were detected in the medial preoptic area, infundibular and premammillary nuclei in addition to the ventromedial nucleus (VMN) where cells were found distributed throughout its medial and lateral divisions. Smaller numbers of AR-expressing cells were identified in the bed nucleus of the stria terminalis and anterior hypothalamic area (AHA) including the paraventricular, but not the supraoptic, nucleus. Double-labelling immunocytochemistry revealed the presence of AR immunoreactivity in only 2 of 460 gonadotropin-releasing hormone (GnRH) neurons. A very small population of TH-immunoreactive cells located in the lateral aspect of the AHA was found to contain ARs. Dopaminergic cells elsewhere in the hypothalamus, including the infundibular nucleus, did not display AR immunoreactivity. Nearly 50% of AR-expressing cells in the lateral VMN were immunoreactive for somatostatin while less than 5% of periventricular somatostatin neurons displayed AR immunoreactivity. These results show where ARs are expressed in the ram hypothalamus and indicate the neuroanatomical sites at which androgen may act to influence reproductive function. The absence of ARs in the neuroendocrine GnRH and tuberoinfundibular dopaminergic cells suggests that androgens do not influence the genome of these cells in any direct manner. In contrast, the somatostatin neurons of the VMN appear to be an important target for circulating androgens in the non-breeding season ram.